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Sample records for high alpha stability

  1. Structure of Bacillus amyloliquefaciens alpha-amylase at high resolution: implications for thermal stability.

    PubMed

    Alikhajeh, Jahan; Khajeh, Khosro; Ranjbar, Bijan; Naderi-Manesh, Hossein; Lin, Yi Hung; Liu, Enhung; Guan, Hong Hsiang; Hsieh, Yin Cheng; Chuankhayan, Phimonphan; Huang, Yen Chieh; Jeyaraman, Jeyakanthan; Liu, Ming Yih; Chen, Chun Jung

    2010-02-01

    The crystal structure of Bacillus amyloliquefaciens alpha-amylase (BAA) at 1.4 A resolution revealed ambiguities in the thermal adaptation of homologous proteins in this family. The final model of BAA is composed of two molecules in a back-to-back orientation, which is likely to be a consequence of crystal packing. Despite a high degree of identity, comparison of the structure of BAA with those of other liquefying-type alpha-amylases indicated moderate discrepancies at the secondary-structural level. Moreover, a domain-displacement survey using anisotropic B-factor and domain-motion analyses implied a significant contribution of domain B to the total flexibility of BAA, while visual inspection of the structure superimposed with that of B. licheniformis alpha-amylase (BLA) indicated higher flexibility of the latter in the central domain A. Therefore, it is suggested that domain B may play an important role in liquefying alpha-amylases, as its rigidity offers a substantial improvement in thermostability in BLA compared with BAA.

  2. Quantum Dot-Induced Phase Stabilization of ..alpha..-CsPbI3 Perovskite for High-Efficiency Photovoltaics

    SciTech Connect

    Swarnkar, Abhishek; Marshall, Ashley R.; Sanehira, Erin M.; Chernomordik, Boris D.; Moore, David T.; Christians, Jeffrey A.; Chakrabarti, Tamoghna; Luther, Joseph M.

    2016-10-07

    We show nanoscale phase stabilization of CsPbI3 quantum dots (QDs) to low temperatures that can be used as the active component of efficient optoelectronic devices. CsPbI3 is an all-inorganic analog to the hybrid organic cation halide perovskites, but the cubic phase of bulk CsPbI3 (..alpha..-CsPbI3) -- the variant with desirable band gap -- is only stable at high temperatures. We describe the formation of ..alpha..-CsPbI3 QD films that are phase-stable for months in ambient air. The films exhibit long-range electronic transport and were used to fabricate colloidal perovskite QD photovoltaic cells with an open-circuit voltage of 1.23 volts and efficiency of 10.77%. These devices also function as light-emitting diodes with low turn-on voltage and tunable emission.

  3. 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.

  4. Hexamethylenetetramine directed synthesis and properties of a new family of alpha-nickel hydroxide organic-inorganic hybrid materials with high chemical stability.

    PubMed

    Liu, Bian-Hua; Yu, Shu-Hong; Chen, Shao-Feng; Wu, Chun-Yan

    2006-03-09

    A new family of organic-inorganic hybrid material of alpha-nickel hydroxide formulated as Ni(OH)2-x(An-)x/n-(C6H12N4)y.zH2O (A=Cl-, CH3COO-, SO4(2-), NO3-; x=0.05-0.18, y=0.09-0.11, z=0.36-0.43) with high stability and adjustable interlayer spacing ranging from 7.21 to 15.12 A has been successfully prepared by a simple hydrothermal method. The effects of various anions and hexamethylenetetramine (HMT) on the d values of alpha-nickel hydroxide have been systematically investigated. This family of hybrid materials is of such high stability that they can stand more than 40 days in 6 M KOH. The product with a formula Ni(OH)1.95(C6H12N4)0.11(Cl-)0.05(H2O)0.36 has a high surface area of about 299.26 m2/g and an average pore diameter of about 45.1 A. The coercivity (Hc) value is ca. 2000 Oe for the sample with a d spacing of 13.14 A. Moreover, the prepared alpha-Ni(OH)2 in our experiment is of high stability in strong alkali solution. Such high stability could be derived from strong chelating interactions between the Ni ions and HMT molecules with the interlayers. This high chemical stability could make this material more suitable for the applications.

  5. Synthesis of stabilized alpha-helical peptides.

    PubMed

    Bernal, Federico; Katz, Samuel G

    2014-01-01

    Stabilized alpha-helical (SAH) peptides are valuable laboratory tools to explore important protein-protein interactions. Whereas most peptides lose their secondary structure when isolated from the host protein, stapled peptides incorporate an all-hydrocarbon "staple" that reinforces their natural alpha-helical structure. Thus, stapled peptides retain their functional ability to bind their native protein targets and serve multiple experimental uses. First, they are useful for structural studies such as NMR or crystal structures that map and better define binding sites. Second, they can be used to identify small molecules that specifically target that interaction site. Third, stapled peptides can be used to test the importance of specific amino acid residues or posttranslational modifications to the binding. Fourth, they can serve as structurally competent bait to identify novel binding partners to specific alpha-helical motifs. In addition to markedly improved alpha-helicity, stapled peptides also display resistance to protease cleavage and enhanced cell permeability. Most importantly, they are useful for intracellular experiments that explore the functional consequences of blocking particular protein interactions. Because of their remarkable stability, stapled peptides can be applied to whole-animal, in vivo studies. Here we describe a protocol for the synthesis of a peptide that incorporates an all-hydrocarbon "staple" employing a ring-closing olefin metathesis reaction. With proper optimization, stapled peptides can be a fundamental, accurate laboratory tool in the modern chemical biologist's armory.

  6. Differential stability of beta-sheets and alpha-helices in beta-lactamase: a high temperature molecular dynamics study of unfolding intermediates.

    PubMed Central

    Vijayakumar, S; Vishveshwara, S; Ravishanker, G; Beveridge, D L

    1993-01-01

    beta-Lactamase, which catalyzes beta-lactam antibiotics, is prototypical of large alpha/beta proteins with a scaffolding formed by strong noncovalent interactions. Experimentally, the enzyme is well characterized, and intermediates that are slightly less compact and having nearly the same content of secondary structure have been identified in the folding pathway. In the present study, high temperature molecular dynamics simulations have been carried out on the native enzyme in solution. Analysis of these results in terms of root mean square fluctuations in cartesian and [phi, psi] space, backbone dihedral angles and secondary structural hydrogen bonds forms the basis for an investigation of the topology of partially unfolded states of beta-lactamase. A differential stability has been observed for alpha-helices and beta-sheets upon thermal denaturation to putative unfolding intermediates. These observations contribute to an understanding of the folding/unfolding processes of beta-lactamases in particular, and other alpha/beta proteins in general. Images FIGURE 1 FIGURE 4 PMID:8312470

  7. Engineering and characterization of a stabilized alpha1/alpha2 module of the class I major histocompatibility complex product Ld.

    PubMed

    Jones, Lindsay L; Brophy, Susan E; Bankovich, Alexander J; Colf, Leremy A; Hanick, Nicole A; Garcia, K Christopher; Kranz, David M

    2006-09-01

    The major histocompatibility complex (MHC) is the most polymorphic locus known, with thousands of allelic variants. There is considerable interest in understanding the diversity of structures and peptide-binding features represented by this class of proteins. Although many MHC proteins have been crystallized, others have not been amenable to structural or biochemical studies due to problems with expression or stability. In the present study, yeast display was used to engineer stabilizing mutations into the class I MHC molecule, Ld. The approach was based on previous studies that showed surface levels of yeast-displayed fusion proteins are directly correlated with protein stability. To engineer a more stable Ld, we selected Ld mutants with increased surface expression from randomly mutated yeast display libraries using anti-Ld antibodies or high affinity, soluble T-cell receptors (TCRs). The most stable Ld mutant, Ld-m31, consisted of a single-chain MHC module containing only the alpha1 and alpha2 domains. The enhanced stability was in part due to a single mutation (Trp-97 --> Arg), shown previously to be present in the allele Lq. Mutant Ld-m31 could bind to Ld peptides, and the specific peptide.Ld-m31 complex (QL9.Ld-m31) was recognized by alloreactive TCR 2C. A soluble form of the Ld-m31 protein was expressed in Escherichia coli and refolded from inclusion bodies at high yields. Surface plasmon resonance showed that TCRs bound to peptide.Ld-m31 complexes with affinities similar to those of native full-length Ld. The TCR and QL9.Ld-m31 formed complexes that could be resolved by native gel electrophoresis, suggesting that stabilized alpha1/alpha2 class I platforms may enable various structural studies.

  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. 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.

  10. 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.

  11. epsilon-COP is a structural component of coatomer that functions to stabilize alpha-COP.

    PubMed Central

    Duden, R; Kajikawa, L; Wuestehube, L; Schekman, R

    1998-01-01

    We isolated a novel yeast alpha-COP mutant, ret1-3, in which alpha-COP is degraded after cells are shifted to a restrictive temperature. ret1-3 cells cease growth at 28 degrees C and accumulate the ER precursor of carboxypeptidase Y (p1 CPY). In a screen for high copy suppressors of these defects, we isolated the previously unidentified yeast epsilon-COP gene. epsilon-COP (Sec28p) overproduction suppresses the defects of ret1-3 cells up to 34 degrees C, through stabilizing levels of alpha-COP. Surprisingly, cells lacking epsilon-COP (sec28 Delta) grow well up to 34 degrees C and display normal trafficking of carboxypeptidase Y and KKXX-tagged proteins at a permissive temperature. epsilon-COP is thus non-essential for yeast cell growth, but sec28 Delta cells are thermosensitive. In sec28 Delta cells shifted to 37 degrees C, wild-type alpha-COP (Ret1p) levels diminish rapidly and cells accumulate p1 CPY; these defects can be suppressed by alpha-COP overproduction. Mutant coatomer from sec28 Delta cells behaves as an unusually large protein complex in gel filtration experiments. The sec28 Delta mutation displays allele-specific synthetic-lethal interactions with alpha-COP mutations: sec28 Delta ret1-3 double mutants are unviable at all temperatures, whereas sec28 Delta ret1-1 double mutants grow well up to 30 degrees C. Our results suggest that a function of epsilon-COP is to stabilize alpha-COP and the coatomer complex. PMID:9463377

  12. High stability amplifier

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    An electrical RF signal amplifier for providing high temperature stability and RF isolation and comprised of an integrated circuit voltage regulator, a single transistor, and an integrated circuit operational amplifier mounted on a circuit board such that passive circuit elements are located on side of the circuit board while the active circuit elements are located on the other side is described. The active circuit elements are embedded in a common heat sink so that a common temperature reference is provided for changes in ambient temperature. The single transistor and operational amplifier are connected together to form a feedback amplifier powered from the voltage regulator with transistor implementing primarily the desired signal gain while the operational amplifier implements signal isolation. Further RF isolation is provided by the voltage regulator which inhibits cross-talk from other like amplifiers powered from a common power supply. Input and output terminals consisting of coaxial connectors are located on the sides of a housing in which all the circuit components and heat sink are located.

  13. Lithium-oxide-stabilized alpha manganese dioxide for rechargeable lithium batteries

    SciTech Connect

    Johnson, C.S.; Dees, D.W.; Mansuetto, M.F.; Thackeray, M.M.; Vissers, D.R.; Argyriou, D.; Loong, C.K.; Christensen, L.

    1996-06-01

    Objective was to increase the reversible cycling capacity of anhydrous {alpha}-MnO{sub 2} by stabilizing its structure. We have synthesized various {alpha}-MnO{sub 2} materials and modified their structures via lithia doping in order to determine what properties are important for controlling cycling performance. A set of new stabilized {alpha}-[xLi{sub 2}O]{center_dot}MnO{sub 2} (x<0.2) cathode materials was synthesized, structurally characterized, and electrochemically evaluated.

  14. 2-Amino-alpha-2'-deoxyadenosine increased duplex stability of methoxyethylphosphoramidate alpha-oligodeoxynucleotides with RNA target.

    PubMed

    Naval, Magali; Michel, Thibaut; Vasseur, Jean-Jacques; Debart, Françoise

    2002-06-03

    A new efficient synthesis of 2-amino-alpha-2'-deoxyadenosine and its incorporation into methoxyethylphosphoramidate alpha-oligodeoxynucleotides (ODNs) via H-phosphonate chemistry were reported. Thermal denaturation experiments demonstrated a significant stabilization of the complexes formed between these analogues and their RNA target (+2 degrees C/NH2A) relative to adenosine-containing phosphoramidate alpha-oligonucleotides. Concerning the binding specificity of these modified ODNs, unlike natural ODNs, discrimination against G pairing is higher and against C pairing is lower.

  15. 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.

  16. 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.

  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. Aggregation patterns in alpha,alpha'-stabilized carbanions: assembly of a sodium cage polymer by slip-stacking of dimers.

    PubMed

    Henderson, Kenneth W; Kennedy, Alan R; MacDougall, Dugald J

    2003-04-21

    The alpha,alpha'-stabilized carbanion complexes [PhSO(2)CHCNNa.THF], 3, [t-BuSO(2)CHCNNa], 4, [PhSO(2)CHCNK], 5, [t-BuSO(2)CHCNK], 6, and [MeSO(2)CHCNLi.TMEDA], 7, have been synthesized via the metalation of the parent (organo)sulfonylacetonitriles by BuLi, BuNa, or BnK in THF solution (or THF/TMEDA in the case of 7). In addition, complexes 3 and 7 have been characterized by single-crystal X-ray analyses and have been found to adopt related structures in the solid state. Complex 7 is a molecular dimer containing a central 12-membered (OSCCNLi)(2) ring core, with each metal rendered tetracoordinate by binding to a chelating TMEDA molecule. As found in related complexes, no direct carbanion to lithium contacts are present in the structure of 7. Complex 3 forms a polymeric cage structure composed of associated "dimeric" (OSCCNNa)(2) rings, similar to those found in 7. The larger sodium cations, and the presence of only one THF molecule/metal, allow additional contacts with the anions, leading to hexacoordination at the metal centers. These contacts include long-range transannular Na-N interactions (2.8042(14) A) across the central dimeric ring and "interdimer" Na-C connections (2.8718(15) A). Dissolution of complexes 3-6 and their lithiated derivatives [PhSO(2)CHCNLi.TMEDA], 1, and [t-BuSO(2)CHCNLi.THF], 2, in DMSO-d(6) results in almost identical chemical shifts for each type of ligand. This suggests that charge-separated complexes of the form [RSO(2)CHCN](-)[M(DMSO-d(6))(n)()](+) are formed in highly polar solution.

  20. 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.

  1. H[alpha]-stability of modified Runge-Kutta methods for nonlinear neutral pantograph equations

    NASA Astrophysics Data System (ADS)

    Ma, S. F.; Yang, Z. W.; Liu, M. Z.

    2007-11-01

    In this paper, we investigate H[alpha]-stability of algebraically stable Runge-Kutta methods with a variable stepsize for nonlinear neutral pantograph equations. As a result, the Radau IA, Radau IIA, Lobatto IIIC method, the odd-stage Gauss-Legendre methods and the one-leg [theta]-method with are H[alpha]-stable for nonlinear neutral pantograph equations. Some experiments are given.

  2. Stability of HAMLET--a kinetically trapped alpha-lactalbumin oleic acid complex.

    PubMed

    Fast, Jonas; Mossberg, Ann-Kristin; Svanborg, Catharina; Linse, Sara

    2005-02-01

    The stability toward thermal and urea denaturation was measured for HAMLET (human alpha-lactalbumin made lethal to tumor cells) and alpha-lactalbumin, using circular dichroism and fluorescence spectroscopy as well as differential scanning calorimetry. Under all conditions examined, HAMLET appears to have the same or lower stability than alpha-lactalbumin. The largest difference is seen for thermal denaturation of the calcium free (apo) forms, where the temperature at the transition midpoint is 15 degrees C lower for apo HAMLET than for apo alpha-lactalbumin. The difference becomes progressively smaller as the calcium concentration increases. Denaturation of HAMLET was found to be irreversible. Samples of HAMLET that have been renatured after denaturation have lost the specific biological activity toward tumor cells. Three lines of evidence indicate that HAMLET is a kinetic trap: (1) It has lower stability than alpha-lactalbumin, although it is a complex of alpha-lactalbumin and oleic acid; (2) its denaturation is irreversible and HAMLET is lost after denaturation; (3) formation of HAMLET requires a specific conversion protocol.

  3. Effect of a nonconstant C/m-alpha/ on the stability of rolling aircraft

    NASA Technical Reports Server (NTRS)

    Davari, B.; Laitone, E. V.

    1977-01-01

    An analytical study is carried out of the behavior of modern high-speed aircraft of inertially slender configurations in maneuvers involving large rates of roll. Inertia cross-coupling, as well as a linear variation of longitudinal static stability (C/m-alpha/) with angle of attack, are considered. The steady-state solutions of the nonlinear equations of motion, based on principal inertia axes, are studied to obtain useful information on the response behavior of the state variables during roll maneuvers. It is shown that, in addition to the critical values of aileron deflection that have been previously found to limit a steady-state roll with constant longitudinal static stability, there can be two new critical values introduced by a linear decrease of the absolute value of longitudinal static stability with angle of attack. For aileron deflections near these critical values, the response of the aircraft exhibits violent oscillations and dangerous peak loads, due to the cross-coupled motion accompanying a roll maneuver. These critical values define a new range of aileron deflections in which no steady-state roll is possible.

  4. Effects of the combination of hydrophobic polypeptides, iso-alpha acids, and malto-oligosaccharides on beer foam stability.

    PubMed

    Ferreira, Isabel M P L V O; Jorge, Kátia; Nogueira, Luciana C; Silva, Filipe; Trugo, Luiz C

    2005-06-15

    The influence of hydrophobic polypeptides concentrated in beer foam, together with the composition of iso-alpha acids and the content of malto-oligosaccharides in beer on foam stability, has been investigated. The objective was to find out whether a shortage of one of these positive contributors to foam stability could be compensated for by an increased presence of another or whether optimum levels of each contributor is necessary. For that purpose, an image analysis method to evaluate beer foam quality was developed. The foam collapse time was the parameter chosen to group beers according to their foam stability. Profiles of hydrophobic polypeptides that concentrate in beer foam, iso-alpha acids, and malto-oligosaccharides of 14 beer brands were acquired by high-performance liquid chromatography. Principal component analysis (PCA) was performed to show the relationship between beer brands and its composition. Beers that contained propylene glycol alginate as a foam enhancer showed high foam stability except for one beer, which had a low content of hydrophobic polypeptides, thereby highlighting the requirement of threshold levels of hydrophobic polypeptides to obtain stable foam. The data of samples that were devoid of a foam additive were subjected to a discriminant statistical analysis. Foam stability declined in proportion to decreases in hydrophobic polypeptides and to a lesser extent to decreases in iso-alpha-acid contents. Apparently, the content of malto-oligosaccharides were found to have no major influence on foam stability. The model of discriminate analysis was found to explain 100% of the variance in data with 85.2% success in classifying all samples according to the model, suggesting that foam stability is mainly governed by the beer constituents evaluated in this study.

  5. 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.

  6. 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.

  7. Sufficient condition for velocity-space stability of the alpha particle distribution in a tokamak reactor

    SciTech Connect

    Cordey, J.G.; Goldston, R.J.; Mikkelsen, D.R.

    1980-08-01

    A condition is derived for the velocity-space distribution of suprathermal alpha particles to be monotonically decreasing with energy - and hence stable to homogeneous plasma instabilities - during the heating phase of a tokamak reactor. This stability condition is easily satisfied for presently envisaged neutral injection heating of reactors, but may be violated in strong heating of smaller plasmas or during fast compressional heating.

  8. Relative activities and stabilities of mutant Escherichia coli tryptophan synthase alpha subunits.

    PubMed Central

    Lim, W K; Shin, H J; Milton, D L; Hardman, J K

    1991-01-01

    In vitro mutagenesis of the Escherichia coli trpA gene has yielded 66 mutant tryptophan synthase alpha subunits containing single amino acid substitutions at 49 different residue sites and 29 double and triple amino acid substitutions at 16 additional sites, all within the first 121 residues of the protein. The 66 singly altered mutant alpha subunits encoded from overexpression vectors have been examined for their ability to support growth in trpA mutant host strains and for their enzymatic and stability properties in crude extracts. With the exception of mutant alpha subunits altered at catalytic residue sites Glu-49 and Asp-60, all support growth; this includes those (48 of 66) that have no enzymatic defects and those (18 of 66) that do. The majority of the enzymatically defective mutant alpha subunits have decreased capacities for substrate (indole-3-glycerol phosphate) utilization, typical of the early trpA missense mutants isolated by in vivo selection methods. These defects vary in severity from complete loss of activity for mutant alpha subunits altered at residue positions 49 and 60 to those, altered elsewhere, that are partially (up to 40 to 50%) defective. The complete inactivation of the proteins altered at the two catalytic residue sites suggest that, as found via in vitro site-specific mutagenesis of the Salmonella typhimurium tryptophan synthetase alpha subunit, both residues probably also participate in a push-pull general acid-base catalysis of indole-3-glycerol phosphate breakdown for the E. coli enzyme as well. Other classes of mutant alpha subunits include some novel types that are defective in their functional interaction with the other tryptophan synthetase component, the beta 2 subunit. Also among the mutant alpha subunits, 19 were found altered at one or another of the 34 conserved residue sites in this portion of the alpha polypeptide sequence; surprisingly, 10 of these have wild-type enzymatic activity, and 16 of these can satisfy growth

  9. 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.

  10. 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.

  11. All-atom model for stabilization of alpha-helical structure in peptides by hydrocarbon staples.

    PubMed

    Kutchukian, Peter S; Yang, Jae Shick; Verdine, Gregory L; Shakhnovich, Eugene I

    2009-04-08

    Recent work has shown that the incorporation of an all-hydrocarbon "staple" into peptides can greatly increase their alpha-helix propensity, leading to an improvement in pharmaceutical properties such as proteolytic stability, receptor affinity, and cell permeability. Stapled peptides thus show promise as a new class of drugs capable of accessing intractable targets such as those that engage in intracellular protein-protein interactions. The extent of alpha-helix stabilization provided by stapling has proven to be substantially context dependent, requiring cumbersome screening to identify the optimal site for staple incorporation. In certain cases, a staple encompassing one turn of the helix (attached at residues i and i+4) furnishes greater helix stabilization than one encompassing two turns (i,i+7 staple), which runs counter to expectation based on polymer theory. These findings highlight the need for a more thorough understanding of the forces that underlie helix stabilization by hydrocarbon staples. Here we report all-atom Monte Carlo folding simulations comparing unmodified peptides derived from RNase A and BID BH3 with various i,i+4 and i,i+7 stapled versions thereof. The results of these simulations were found to be in quantitative agreement with experimentally determined helix propensities. We also discovered that staples can stabilize quasi-stable decoy conformations, and that the removal of these states plays a major role in determining the helix stability of stapled peptides. Finally, we critically investigate why our method works, exposing the underlying physical forces that stabilize stapled peptides.

  12. 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.

  13. 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.

  14. Low resolution structure of the human alpha4 protein (IgBP1) and studies on the stability of alpha4 and of its yeast ortholog Tap42.

    PubMed

    Smetana, Juliana Helena Costa; Oliveira, Cristiano Luiz Pinto; Jablonka, Willy; Aguiar Pertinhez, Thelma; Carneiro, Flavia Raquel Gonçalves; Montero-Lomeli, Monica; Torriani, Iris; Zanchin, Nilson Ivo Tonin

    2006-04-01

    The yeast Tap42 and mammalian alpha4 proteins belong to a highly conserved family of regulators of the type 2A phosphatases, which participate in the rapamycin-sensitive signaling pathway, connecting nutrient availability to cell growth. The mechanism of regulation involves binding of Tap42 to Sit4 and PPH21/22 in yeast and binding of alpha4 to the catalytic subunits of type 2A-related phosphatases PP2A, PP4 and PP6 in mammals. Both recombinant proteins undergo partial proteolysis, generating stable N-terminal fragments. The full-length proteins and alpha4 C-terminal deletion mutants at amino acids 222 (alpha4Delta222), 236 (alpha4Delta236) and 254 (alpha4Delta254) were expressed in E. coli. alpha4Delta254 undergoes proteolysis, producing a fragment similar to the one generated by full-length alpha4, whereas alpha4Delta222 and alpha4Delta236 are highly stable proteins. alpha4 and Tap42 show alpha-helical circular dichroism spectra, as do their respective N-terminal proteolysis resistant products. The cloned truncated proteins alpha4Delta222 and alpha4Delta236, however, possess a higher content of alpha-helix, indicating that the C-terminal region is less structured, which is consistent with its higher sensitivity to proteolysis. In spite of their higher secondary structure content, alpha4Delta222 and alpha4Delta236 showed thermal unfolding kinetics similar to the full-length alpha4. Based on small angle X-ray scattering (SAXS), the calculated radius of gyration for alpha4 and Tap42 were 41.2 +/- 0.8 A and 42.8 +/- 0.7 A and their maximum dimension approximately 142 A and approximately 147 A, respectively. The radii of gyration for alpha4Delta222 and alpha4Delta236 were 21.6 +/- 0.3 A and 25.7 +/- 0.2 A, respectively. Kratky plots show that all studied proteins show variable degree of compactness. Calculation of model structures based on SAXS data showed that alpha4Delta222 and alpha4Delta236 proteins have globular conformation, whereas alpha4 and Tap42 exhibit

  15. Thermodynamic stability of a cold-active alpha-amylase from the Antarctic bacterium Alteromonas haloplanctis.

    PubMed

    Feller, G; d'Amico, D; Gerday, C

    1999-04-06

    The thermal stability of the cold-active alpha-amylase (AHA) secreted by the Antarctic bacterium Alteromonas haloplanctis has been investigated by intrinsic fluorescence, circular dichroism, and differential scanning calorimetry. It was found that this heat-labile enzyme is the largest known multidomain protein exhibiting a reversible two-state unfolding, as demonstrated by the recovery of DeltaHcal values after consecutive calorimetric transitions, a DeltaHcal/DeltaHeff ratio close to unity, and the independence of unfolding thermodynamic parameters of scan rates. By contrast, the mesophilic alpha-amylases investigated here (from porcine pancreas, human salivary glands, yellow meal beetle, Bacillus amyloliquefaciens, and Bacillus licheniformis) unfold irreversibly according to a non-two-state mechanism. Unlike mesophilic alpha-amylases, the melting point of AHA is independent of calcium and chloride binding while the allosteric and structural functions of these ions are conserved. The thermostability of AHA at optimal conditions is characterized by a Tm of 43.7 degrees C, a DeltaHcal of 238 kcal mol-1, and a DeltaCp of 8.47 kcal mol-1 K-1. These values were used to calculate the Gibbs free energy of unfolding over a wide range of temperatures. This stability curve shows that (a) the specific DeltaGmax of AHA [22 cal (mol of residue)-1] is 4 times lower than that of mesophilic alpha-amylases, (b) group hydration plays a crucial role in the enzyme flexibility at low temperatures, (c) the temperature of cold unfolding closely corresponds to the lower limit of bacterial growth, and (d) the recombinant heat-labile enzyme can be expressed in mesophilic hosts at moderate temperatures. It is also argued that the cold-active alpha-amylase has evolved toward the lowest possible conformational stability of its native state.

  16. 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.

  17. The noncatalytic triad of alpha-amylases: a novel structural motif involved in conformational stability.

    PubMed

    Marx, Jean-Claude; Poncin, Johan; Simorre, Jean-Pierre; Ramteke, Pramod W; Feller, Georges

    2008-02-01

    Chloride-activated alpha-amylases contain a noncatalytic triad, independent of the glycosidic active site, perfectly mimicking the catalytic triad of serine-proteases and of other active serine hydrolytic enzymes. Mutagenesis of Glu, His, and Ser residues in various alpha-amylases shows that this pattern is a structural determinant of the enzyme conformation that cannot be altered without losing the intrinsic stability of the protein. (1)H-(15)N NMR spectra of a bacterial alpha-amylase reveal proton signals that are identical with the NMR signature of catalytic triads and especially a deshielded proton involving a protonated histidine and displaying properties similar to that of a low barrier hydrogen bond. It is proposed that the H-bond between His and Glu of the noncatalytic triad is an unusually strong interaction, responsible for the observed NMR signal and for the weak stability of the triad mutants. Furthermore, a stringent template-based search of the Protein Data Bank demonstrated that this motif is not restricted to alpha-amylases, but is also found in 80 structures from 33 different proteins, amongst which SH2 domain-containing proteins are the best representatives.

  18. 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.

  19. 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.

  20. Competing interactions contributing to alpha-helical stability in aqueous solution.

    PubMed Central

    Bodkin, M. J.; Goodfellow, J. M.

    1995-01-01

    The stability of a 15-residue peptide has been investigated using CD spectroscopy and molecular simulation techniques. The sequence of the peptide was designed to include key features that are known to stabilize alpha-helices, including ion pairs, helix dipole capping, peptide bond capping, and aromatic interactions. The degree of helicity has been determined experimentally by CD in three solvents (aqueous buffer, methanol, and trifluoroethanol) and at two temperatures. Simulations of the peptide in the aqueous system have been performed over 500 ps at the same two temperatures using a fully explicit solvent model. Consistent with the CD data, the degree of helicity is decreased at the higher temperature. Our analysis of the simulation results has focused on competition between different side-chain/side-chain and side-chain/main-chain interactions, which can, in principle, stabilize the helix. The unfolding in aqueous solution occurs at the amino terminus because the side-chain interactions are insufficient to stabilize both the helix dipole and the peptide hydrogen bonds. Loss of capping of the peptide backbone leads to water insertion within the first peptide hydrogen bond and hence unfolding. In contrast, the carboxy terminus of the alpha-helix is stable in both simulations because the C-terminal lysine residue stabilizes the helix dipole, but at the expense of an ion pair. PMID:7613460

  1. Oxidative stability and alpha-tocopherol retention in soybean oil with lemon seed extract (Citrus limon) under thermoxidation.

    PubMed

    Luzia, Débora Maria Moreno; Jorge, Neuza

    2009-11-01

    The synergistic effect of lemon seed extract with tert-butylhydroquinone (TBHQ) in soybean oil subjected to thermoxidation by Rancimat was investigated, and the influence of these antioxidants on a-tocopherol degradation in thermoxidized soybean oil. Control, LSE (2400 mg/kg Lemon Seed Extract), TBHQ (50 mg/kg), Mixture 1 (LSE + 50 mg/kg TBHQ) and Mixture 2 (LSE + 25 mg/kg TBHQ) were subjected to 180 degrees C for 20 h. Samples were taken at time 0, 5, 10, 15 and 20 h intervals and analysed for oxidative stability and alpha-tocopherol content. LSE and Mixtures 1 and 2 showed the capacity of retarding lipid oxidation when added to soya oil and also contributed to alpha-tocopherol retention in oil heated at high temperatures. However, Mixtures 1 and 2 added to the oil presented a greater antioxidant power, consequently proving the antioxidants synergistic effect.

  2. 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.

  3. ''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.

  4. Influence of carbohydrates on the stability and structure of a hyperglycosylated human interferon alpha mutein.

    PubMed

    Ceaglio, Natalia; Etcheverrigaray, Marina; Kratje, Ricardo; Oggero, Marcos

    2010-08-01

    Protein physical and chemical instability is one of the major challenges in the development of biopharmaceuticals during every step of the process, ranging from production to final delivery. This is particularly applicable to human recombinant interferon alpha-2b (rhIFN-alpha2b), a pleiotropic cytokine currently used worldwide for the treatment of various cancer and chronic viral diseases, which presents a poor stability in solution. In previous studies, we have demonstrated that the introduction of four N-glycosylation sites in order to construct a heavily glycosylated IFN variant (4N-IFN) resulted in a markedly prolonged plasma half-life which was reflected in an enhanced therapeutic activity in mice in comparison with the commercial non-glycosylated rhIFN-alpha2b (NG-IFN). Herein, we evaluated the influence of glycosylation on the in vitro stability of 4N-IFN towards different environmental conditions. Interestingly, the hyperglycosylated cytokine showed enhanced stability against thermal stress, acid pH and repetitive freeze-thawing cycles in comparison with NG-IFN. Besides, microcalorimetric analysis indicated a much higher melting temperature of 4N-IFN, also demonstrating a higher solubility of this variant as denoted by the absence of precipitation at the end of the experiment, in contrast with the NG-IFN behaviour. Furthermore, far-UV circular dichroism (CD) spectrum of 4N-IFN was virtually superimposed with that of NG-IFN, indicating that the IFN structure was not altered by the addition of carbohydrate moieties. The same conclusion could be inferred from limited proteolysis studies. Our results suggest that glycoengineering could be a useful strategy for protecting rhIFN-alpha2b from inactivation by various external factors and for overcoming aggregation problems during the production process and storage.

  5. Predicting stability of alpha-helical, orthogonal-bundle proteins on surfaces

    NASA Astrophysics Data System (ADS)

    Wei, Shuai; Knotts, Thomas A.

    2010-09-01

    The interaction of proteins with surfaces is a key phenomenon in many applications, but current understanding of the biophysics involved is lacking. At present, rational design of such emerging technologies is difficult as no methods or theories exist that correctly predict how surfaces influence protein behavior. Using molecular simulation and a coarse-grain model, this study illustrates for the first time that stability of proteins on surfaces can be correlated with tertiary structural elements for alpha-helical, orthogonal-bundle proteins. Results show that several factors contribute to stability on surfaces including the nature of the loop region where the tether is placed and the ability of the protein to freely rotate on the surface. A thermodynamic analysis demonstrates that surfaces stabilize proteins entropically and that any destabilization is an enthalpic effect. Moreover, the entropic effects are concentrated on the unfolded state of the protein while the ethalpic effects are focused on the folded state.

  6. Predicting stability of alpha-helical, orthogonal-bundle proteins on surfaces.

    PubMed

    Wei, Shuai; Knotts, Thomas A

    2010-09-21

    The interaction of proteins with surfaces is a key phenomenon in many applications, but current understanding of the biophysics involved is lacking. At present, rational design of such emerging technologies is difficult as no methods or theories exist that correctly predict how surfaces influence protein behavior. Using molecular simulation and a coarse-grain model, this study illustrates for the first time that stability of proteins on surfaces can be correlated with tertiary structural elements for alpha-helical, orthogonal-bundle proteins. Results show that several factors contribute to stability on surfaces including the nature of the loop region where the tether is placed and the ability of the protein to freely rotate on the surface. A thermodynamic analysis demonstrates that surfaces stabilize proteins entropically and that any destabilization is an enthalpic effect. Moreover, the entropic effects are concentrated on the unfolded state of the protein while the ethalpic effects are focused on the folded state.

  7. 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.

  8. [On the changes in alpha-chymotrypsin stability after its modification by polyelectrolytes].

    PubMed

    Bessmertnaia, L Ia; Kozlov, L V; Antonov, V K

    1977-10-01

    Reversible thermal denaturation of alpha-chymotrypsin, its electrostatic complexes with carboxyl-containing polymers and the enzyme covalently bound with those polymers were studied. It was shown that the enzyme stability is affected by matrix, which manifests itself in a simultaneous decrease in enthalpy and enthropy of the reversible denaturation process and a simultaneous decrease in activation enthalpy and enthropy of denaturation. Modification and complexing of chymotrypsin with polymers has practically no effect on the activation parameters of renaturation. Differences in the original states of alpha-chymotrypsin and its derivatives and similarity of their activated states are proposed. The formation of ionic complexes of enzyme or covalent binding to polymers results in alteration of the protein native state similar to the denaturated state.

  9. Contemporary strategies for the stabilization of peptides in the alpha-helical conformation.

    PubMed

    Henchey, Laura K; Jochim, Andrea L; Arora, Paramjit S

    2008-12-01

    Herein we review contemporary synthetic and protein design strategies to stabilize the alpha-helical motif in short peptides and miniature proteins. Advances in organometallic catalyst design, specifically for the olefin metathesis reaction, enable the use of hydrocarbon bridges to either crosslink side chains of specific residues or mimic intramolecular hydrogen bonds with carbon-carbon bonds. The resulting hydrocarbon-stapled and hydrogen bond surrogate alpha-helices provide unique synthetic ligands for targeting biomolecules. In the protein design realm, several classes of miniature proteins that display stable helical domains have been engineered and manipulated with powerful in vitro selection technologies to yield libraries of sequences that retain their helical folds. Rational re-design of these scaffolds provide distinctive reagents for the modulation of protein-protein interactions.

  10. Protein stabilization via hydrophilization. Covalent modification of trypsin and alpha-chymotrypsin.

    PubMed

    Mozhaev, V V; Siksnis, V A; Melik-Nubarov, N S; Galkantaite, N Z; Denis, G J; Butkus, E P; Zaslavsky BYu; Mestechkina, N M; Martinek, K

    1988-04-05

    This paper experimentally verifies the idea presented earlier that the contact of nonpolar clusters located on the surface of protein molecules with water destabilizes proteins. It is demonstrated that protein stabilization can be achieved by artificial hydrophilization of the surface area of protein globules by chemical modification. Two experimental systems are studied for the verification of the hydrophilization approach. The surface tyrosine residues of trypsin are transformed to aminotyrosines using a two-step modification procedure: nitration by tetranitromethane followed by reduction with sodium dithionite. The modified enzyme is much more stable against irreversible thermoinactivation: the stabilizing effect increases with the number of aminotyrosine residues in trypsin and the modified enzyme can become even 100 times more stable than the native one. Alpha-chymotrypsin is covalently modified by treatment with anhydrides or chloroanhydrides of aromatic carboxylic acids. As a result, different numbers of additional carboxylic groups (up to five depending on the structure of the modifying reagent) are introduced into each Lys residue modified. Acylation of all available amino groups of alpha-chymotrypsin by cyclic anhydrides of pyromellitic and mellitic acids results in a substantial hydrophilization of the protein as estimated by partitioning in an aqueous Ficoll-400/Dextran-70 biphasic system. These modified enzyme preparations are extremely stable against irreversible thermal inactivation at elevated temperatures (65-98 degrees C); their thermostability is practically equal to the stability of proteolytic enzymes from extremely thermophilic bacteria, the most stable proteinases known to date.

  11. Non-covalent inclusion of ferulic acid with alpha-cyclodextrin improves photo-stability and delivery: NMR and modeling studies.

    PubMed

    Anselmi, Cecilia; Centini, Marisanna; Maggiore, Maria; Gaggelli, Nicola; Andreassi, Marco; Buonocore, Anna; Beretta, Giangiacomo; Facino, Roberto Maffei

    2008-03-13

    Ferulic acid (FA) is a highly effective antioxidant and photo-protective agent, already approved in Japan as a sunscreen, but it is poorly suited for cosmetic application because of its low physicochemical stability. We prepared the inclusion complex of FA with alpha-cyclodextrin by co-precipitation from an aqueous solution, and used (1)H NMR and molecular dynamics to investigate the most probable structure of the inclusion complex. In rotating frame nuclear Overhouser effect spectroscopy (ROESY) experiments FA penetrated the alpha-CD hydrophobic cavity with the alpha,beta-unsaturated part of the molecule and some of its aromatic skeleton. In proton chemical shift measurements of FA and alpha-cyclodextrins we determined the stoichiometry of the association complex (1:1) by Job's method, and its stability constant (K(1:1) 1162+/-140 M(-1)) and described the molecular dynamics of the complex on the basis of theoretical studies. Encapsulation with alpha-cyclodextrin improves (i) the chemical stability of FA against UVB stress (10 MED [Minimal Erythemal Dose: 1 MED=25 mJ/cm(2) for skin phototype II: 30]), since no degradation products are formed after irradiation, and (ii) the bioavailability of FA on the skin, slowing its delivery (Strainer cell model).

  12. Alpha-haemoglobin stabilizing protein (AHSP) stabilizes apo-α-haemoglobin in a partially folded state

    PubMed Central

    Krishna Kumar, Kaavya; Dickson, Claire F.; Weiss, Mitchell J.; Mackay, Joel P.; Gell, David A.

    2015-01-01

    SYNOPSIS To produce functional haemoglobin, nascent α-globin (αo) and β-globin (βo) chains must each bind a single haem molecule (to form αh and βh) and interact together to form heterodimers. The precise sequence of binding events is unknown, and it has been suggested that additional factors might enhance the efficiency of Hb folding. The α-haemoglobin stabilizing protein (AHSP) has previously been shown to bind αh and regulate redox activity of the haem iron. Here, we use a combination of classical and dynamic light scattering and NMR spectroscopy to demonstrate that AHSP forms a heterodimeric complex with αo that inhibits αo aggregation and promotes αo folding in the absence of haem. These findings indicate that AHSP may function as an αo-specific chaperone, and suggest an important role for αo in guiding Hb assembly by stabilizing βo and inhibiting off-pathway self-association of βh. PMID:20860551

  13. 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.

  14. 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.

  15. 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.

  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.

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

    NASA Astrophysics Data System (ADS)

    Lissauer, Jack J.; Quarles, Billy L.

    2016-10-01

    The alpha Centauri star system contains the Solar Systems closest stellar neighbors. If an earthlike planet is present in the system, it could in principle be detected using a small space-based telescope (Belikov et al. 2105, Proc. SPIE 9605, 960518). 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 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. Because the binary companion induces a forced eccentricity upon the orbits of planets in orbit around either star, appropriately-phased circumstellar orbits with small initial eccentricities are stable to somewhat larger initial semimajor axes than are initially circular orbits and the initial mean anomaly of planets is a factor in determining stability. Our results can guide observers designing instrumentation and search strategies to attempt to discover planets orbiting the nearest sunlike stars.

  19. 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.

  20. New Hubble Space Telescope Observations of High-Velocity Ly(alpha) and H(alpha) in SNR 1987A

    NASA Technical Reports Server (NTRS)

    Michael, Eli; McCray, Richard; Pun, C. S. J.; Borkowski, Kazimierz; Garnavich, Peter; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger; Filippenko, Alexei V.; Fransson, Claes; Panagia, Nino; Phillips, Mark; Schmidt, Brian; Suntzef, Nicholas

    1998-01-01

    We describe and model high-velocity (approximately 15,000 km S(exp -1)) Ly Alpha and H Alpha emission from the supernova remnant SNR 1987A seen in 1997 September and October with the Space Telescope Imaging Spectrograph. Part of this emission comes from a reverse shock located at approximately 75% of the radius of the inner boundary ofthe innercircumstellar ring and confined within + or - 30 degrees of the equatorial plane. Departure from axisymmetry in the Ly Alpha and H Alpha emission correlates with that seen in nonthermal radio emission and reveals an asymmetry in the circumstellar gas distribution. We also see diffuse high-velocity Ly-Alpha emission from supernova debris inside the reverse shock that may be due to excitation by nonthermal particles accelerated by the shock.

  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. 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.

  3. Role of hydrophobicity and solvent-mediated charge-charge interactions in stabilizing alpha-helices.

    PubMed Central

    Vila, J A; Ripoll, D R; Villegas, M E; Vorobjev, Y N; Scheraga, H A

    1998-01-01

    A theoretical study to identify the conformational preferences of lysine-based oligopeptides has been carried out. The solvation free energy and free energy of ionization of the oligopeptides have been calculated by using a fast multigrid boundary element method that considers the coupling between the conformation of the molecule and the ionization equilibria explicitly, at a given pH value. It has been found experimentally that isolated alanine and lysine residues have somewhat small intrinsic helix-forming tendencies; however, results from these simulations indicate that conformations containing right-handed alpha-helical turns are energetically favorable at low values of pH for lysine-based oligopeptides. Also, unusual patterns of interactions among lysine side chains with large hydrophobic contacts and close proximity (5-6 A) between charged NH3+ groups are observed. Similar arrangements of charged groups have been seen for lysine and arginine residues in experimentally determined structures of proteins available from the Protein Data Bank. The lowest-free-energy conformation of the sequence Ac-(LYS)6-NMe from these simulations showed large pKalpha shifts for some of the NH3+ groups of the lysine residues. Such large effects are not observed in the lowest-energy conformations of oligopeptide sequences with two, three, or four lysine residues. Calculations on the sequence Ac-LYS-(ALA)4-LYS-NMe also reveal low-energy alpha-helical conformations with interactions of one of the LYS side chains with the helix backbone in an arrangement quite similar to the one described recently by (Proc. Natl. Acad. Sci. U.S.A. 93:4025-4029). The results of this study provide a sound basis with which to discuss the nature of the interactions, such as hydrophobicity, charge-charge interaction, and solvent polarization effects, that stabilize right-handed alpha-helical conformations. PMID:9826588

  4. Acute toxicity of high doses of the glycoalkaloids, alpha-solanine and alpha-chaconine, in the Syrian Golden hamster.

    PubMed

    Langkilde, Søren; Schrøder, Malene; Stewart, Derek; Meyer, Otto; Conner, Sean; Davies, Howard; Poulsen, Morten

    2008-09-24

    Sprouted, stressed, or spoiled potato tubers have reportedly led to human acute intoxication, coma, and death when consumed in high amounts. These effects have been attributed to glycoalkaloids (GAs), primarily alpha-solanine and alpha-chaconine, naturally present in all potatoes. The level of GAs in potato tubers has previously been shown to increase substantially as a result of improper handling and postharvest storage. A short-term study was performed to investigate the dose-response profile of alpha-solanine and alpha-chaconine alone or in combination, administered daily by oral gavage to Syrian Golden hamsters. Daily doses of 100 mg of alpha-solanine [kg body weight (BW)] (-1) induced death in two of four hamsters within 4 days, when administered by gavage to female Syrian hamsters. Doses of 100 mg of alpha-chaconine alone or alpha-solanine and alpha-chaconine combined in a ratio of 1:2.5, in doses of 75 or 100 mg (kg BW) (-1), induced death in one of four hamsters within the same period. Animals dosed with alpha-solanine alone or in combination with alpha-chaconine suffered from fluid-filled and dilated small intestines. The GA administration had no effect on acetyl cholinesterase (AChE) or butyryl cholinesterase (BuChE) activity in plasma or brain. Liquid chromatography-mass spectrometry-based metabolomics showed that there was a specific accumulation of alpha-chaconine in the liver tissues. In addition, metabolomics gave direct evidence of glycolytic metabolism of the GA with the beta 1, beta 2, and gamma-GAs detected in the urine and, to a lesser extent, the feces. Doses from 75 mg (kg BW) (-1) of alpha-chaconine, alpha-solanine, or the two compounds combined were potentially lethal within 4-5 days in the Syrian Golden hamster. However, the cause of death in these studies could not be established. No synergistic effects of alpha-solanine combined with alpha-chaconine were evident.

  5. 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.

  6. A corona stabilized, high PRF closing switch

    SciTech Connect

    MacGregor, S.J.; Turnbull, S.M.; Tuema, F.A.

    1996-12-31

    This paper explains how the phenomenon of corona stabilization can be applied to high voltage, high PRF switching. A sealed corona stabilized spark gap has been operated at voltages of up to 50 kV, currents of up to 2 kA, and pulse repetition frequencies (PRFs) of up to 1 kHz and up to 5 kHz in burst mode. The effect of the corona is to stabilize the conditions in the switch at short times after breakdown and to create a suitable period for the reapplied voltage to reach the previous level before breakdown occurs. The switch therefore exhibits a much faster voltage recovery time compared to a more conventional uniform field spark gap and can therefore operate at high PRFs.

  7. Oxygen association-dissociation and stability analysis on mouse hemoglobins with mutant alpha- and beta-globins.

    PubMed

    D'Surney, S J; Popp, R A

    1992-10-01

    Oxygen association-dissociation and hemoglobin stability analysis were performed on mouse hemoglobins with amino acid substitutions in an alpha-globin (alpha 89, His to Leu) and a beta-globin (beta 59, Lys to Ile). The variant alpha-globin, designated chain 5m in the Hbag2 haplotype, had an high oxygen affinity and was stable. The variant beta-globin, (beta s2) of the Hbbs2 haplotype, also had an elevated oxygen affinity and in addition was moderately unstable in 19% isopropanol. Hemoglobins from the expected nine (Hbag2/Hbag2;Hbbs/Hbbs x Hbaa/Hbaa;Hbbs2/Hbbs2) F2 genotypes can be grouped into five classes of P50 values characterized by strict additivity and dependency on mutant globin gene dosage; physiologically, both globin variants gave indistinguishable effects on oxygen affinity. The hemoglobin of normal mice (Hbaa/Hbaa;Hbbs/Hbbs) had a P50 = 40 mm Hg and the hemoglobin of Hbag2/Hbag2;Hbbs2/Hbbs2 F2 mice had a P50 = 25 mm Hg (human P50 = 26 mm Hg). Peripheral blood from Hbag2/Hbag2;Hbbs/Hbbs, Hbaa/Hbaa;Hbbs2/Hbbs2 and Hbag2/Hbag2;Hbbs2/Hbbs2 mice exhibited normal hematological values except for a slightly higher hematocrit for Hbag2/Hbag2;Hbbs/Hbbs and Hbag2/Hbag2;Hbbs2/Hbbs2 mice, slightly elevated red cell counts for mice of the three mutant genotypes, and significantly lower values for the mean corpuscular volume and mean corpuscular hemoglobin for Hbag2/Hbag2;Hbbs2/Hbbs2 mice.

  8. 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.

  9. 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.

  10. Stabilizing the integrin alpha M inserted domain in alternative conformations with a range of engineered disulfide bonds.

    PubMed

    Shimaoka, Motomu; Lu, Chafen; Salas, Azucena; Xiao, Tsan; Takagi, Junichi; Springer, Timothy A

    2002-12-24

    Conformational movement of the C-terminal alpha7 helix in the integrin inserted (I) domain, a major ligand-binding domain that adopts an alpha/beta Rossmann fold, has been proposed to allosterically regulate ligand-binding activity. Disulfide bonds were engineered here to reversibly lock the position of the alpha7 helix in one of two alternative conformations seen in crystal structures, termed open and closed. Our results show that pairs of residues with Cbeta atoms farther apart than optimal for disulfide bond stereochemistry can be successfully replaced by cysteine, suggesting that backbone movement accommodates disulfide formation. We also find more success with substituting partially exposed than buried residues. Disulfides stabilizing the open conformation resulted in constitutively active alphaMbeta2 heterodimers and isolated alphaM inserted domains, which were reverted to an inactive form by dithiothreitol reduction. By contrast, a disulfide stabilizing the closed conformation resulted in inactive alphaMbeta2 that was resistant to activation but became activatable after dithiothreitol treatment.

  11. Probing the alpha-helical structural stability of stapled p53 peptides: molecular dynamics simulations and analysis.

    PubMed

    Guo, Zuojun; Mohanty, Udayan; Noehre, Justin; Sawyer, Tomi K; Sherman, Woody; Krilov, Goran

    2010-04-01

    Reactivation of the p53 cell apoptosis pathway through inhibition of the p53-hDM2 interaction is a viable approach to suppress tumor growth in many human cancers and stabilization of the helical structure of synthetic p53 analogs via a hydrocarbon cross-link (staple) has been found to lead to increased potency and inhibition of protein-protein binding (J. Am. Chem. Soc. 129: 5298). However, details of the structure and dynamic stability of the stapled peptides are not well understood. Here, we use extensive all-atom molecular dynamics simulations to study a series of stapled alpha-helical peptides over a range of temperatures in solution. The peptides are found to exhibit substantial variations in predicted alpha-helical propensities that are in good agreement with the experimental observations. In addition, we find significant variation in local structural flexibility of the peptides with the position of the linker, which appears to be more closely related to the observed differences in activity than the absolute alpha-helical stability. These simulations provide new insights into the design of alpha-helical stapled peptides and the development of potent inhibitors of alpha-helical protein-protein interfaces.

  12. Stabilization of alpha-chymotrypsin by covalent immobilization on amine-functionalized superparamagnetic nanogel.

    PubMed

    Hong, Jun; Gong, Peijun; Xu, Dongmei; Dong, Li; Yao, Side

    2007-02-20

    Stabilization of alpha-chymotrypsin (CT) by covalent immobilization on the amine-functionalized magnetic nanogel was studied. The amino groups containing superparamagnetic nanogel was obtained by Hoffman degradation of the polyacrylamide (PAM)-coated Fe(3)O(4) nanoparticles prepared by facile photochemical in situ polymerization. CT was then covalently bound to the magnetic nanogel with reactive amino groups by using 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide as coupling reagent. The binding capacity was determined to be 61mg enzyme/g nanogel by BCA protein assay. Specific activity of the immobilized CT was measured to be 0.93U/(mgmin), 59.3% as that of free CT. The obtained immobilized enzyme had better resistance to temperature and pH inactivation in comparison to free enzyme and thus widened the ranges of reaction pH and temperature. The immobilized enzyme exhibited good thermostability, storage stability and reusability. Kinetic parameters were determined for both the immobilized and free enzyme. The value of K(m) of the immobilized enzyme was larger than did the free form, whereas the V(max) was smaller for the immobilized enzyme.

  13. Microstructure Evolution in Alpha Iron during High Temperature Tensile Deformation

    NASA Astrophysics Data System (ADS)

    Thanh, Phi Hung Xuan

    The microstructural evolution of alpha iron under tensile deformation at high temperature (TH 0.5) and slow strain-rate (10-5 s-1 to 10-5 s-1) was investigated. The impetus for this study was the recent observation of Dynamic Abnormal Grain Growth (DAGG) in pure molybdenum under the same testing conditions. A high temperature tensile testing system was refurbished and assembled for this study. The testing system consists of an Centorr 2229 furnace system mounted on an Instron 1331 load frame. I designed the tensile grip and programmed the testing program to obtain data in the stress and strain regime of interest. Testing were done at both UC Davis and Los Alamos National Labs (LANL). Metallography techniques and electron backscattering diffraction (EBSD) technique in a scanning electron microscope were used to characterize the samples after testing. In addition to normal tensile tests at constant strain-rates where DAGG is proposed to occur, a series of strain-rate change tests were designed and performed. Strain-rate change tests were employed to extract activation area information that provided insight into the active mechanism of deformation of the material in addition to the information obtained from analysis of the stress-strain curve and the microstructure via optical microscopy and EBSD. The obtained stress-train curve data were compared with the stress-strain curves data in the literature for alpha iron in similar regime of deformation indicating that the dominant mechanism of deformation is dynamic recovery. The comparison includes past stress-strain curves and the data recorded in the Ashby Map. Optical and EBSD analysis showed that normal grain growth occurred in alpha iron during this testing regime. This lack of grain boundary pinning by impurity differs from that observed in Mo that exhibited DAGG. Activation area analysis showed that the activation area values of Fe are consistent with friction drag from the lattice being the active deformation

  14. 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.

  15. [1-(Phenylseleno)alkyl]stannanes-mixed selenium/tin analogs of acetals: preparation from alpha-hydroxystannanes and use for generating selenium-stabilized carbanions.

    PubMed

    Fernandopulle, Shimal C; Clive, Derrick L J; Yu, Maolin

    2008-08-01

    Selenium-stabilized carbanions are available by a route that does not involve acid-catalyzed formation of selenoacetals. Aldehydes are converted first into alpha-hydroxystannanes and then into alpha-(phenylseleno)stannanes. Treatment with BuLi affords selenium-stabilized carbanions by preferential Sn/Li exchange.

  16. 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.

  17. Effect of water content on the solid-state stability in two isomorphic clathrates of cephalosporin: cefazolin sodium pentahydrate (alpha form) and FK041 hydrate.

    PubMed

    Mimura, Hisashi; Gato, Katsuhiko; Kitamura, Satoshi; Kitagawa, Teruyuki; Kohda, Shigetaka

    2002-06-01

    This study clearly demonstrates that clathrated water molecules can contribute to both chemical stabilization and destabilization of clathrates. The solid-state stabilities for two isomorphic clathrates of cephalosporin, cefazolin sodium and FK041, were investigated in terms of the effects of water content. The isomorphic ranges of water content were estimated to be 3.5-5 mol/mol for alpha-form cefazolin sodium and 2-4 mol/mol for FK041 hydrate. Upon the isomorphic dehydration, alpha-form cefazolin sodium was destabilized as the water content decreased below 4.25 mol/mol owing to the disruption of hydrogen bonding network in lattice channels. In this case, the hydration of clathrated water up to 4.25 mol/mol contributed to the physical and chemical stability of the crystals. On the contrary, the isomorphic hydration in FK041 hydrate contributed to the chemical destabilization owing to the high water activity. The difference in water activity between alpha-form cefazolin sodium and FK041 hydrate could be attributed to the size of water channels.

  18. 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.

  19. Short communication: Carora cattle show high variability in alpha(s1)-casein.

    PubMed

    Caroli, A; Chessa, S; Chiatti, F; Rignanese, D; Meléndez, B; Rizzi, R; Ceriotti, G

    2008-01-01

    The objective of this study was to analyze the genetic variability of milk proteins of the Carora, a shorthorned Bos taurus cattle breed in Venezuela and in other Southern American countries that is primarily used for milk production. A total of 184 individual milk samples were collected from Carora cattle in 5 herds in Venezuela. The milk protein genes alpha(s1)-casein (CN) (CSN1S1), beta-CN (CSN2), kappa-CN (CSN3), and beta-lactoglobulin (LGB) were typed at the protein level by isoelectrofocusing. It was necessary to further analyze CSN1S1 at the DNA level by a PCR-based method to distinguish CSN1S1*G from B. Increased variation was found in particular at the CSN1S1 gene, where 4 variants were identified. The predominant variant was CSN1S1*B (frequency = 0.8). The second most common CSN1S1 variant was CSN1S1*G (0.101), followed by CSN1S1*C (0.082). Moreover, a new isoelectrofocusing pattern was identified, which may result from a novel CSN1S1 variant, named CSN1S1*I, migrating at an intermediate position between CSN1S1*B and CSN1S1*C. Six cows carried the variant at the heterozygous condition. For the other loci, predominance of CSN2*A2 (0.764), CSN3*B (0.609), and LGB*B (0.592) was observed. Haplotype frequencies (AF) at the CSN1S1-CSN2-CSN3 complex were also estimated by taking association into account. Only 7 haplotypes showed AF values >0.05, accounting for a cumulative frequency of 0.944. The predominant haplotype was B-A2-B (frequency = 0.418), followed by B-A2-A (0.213). The occurrence of the G variant is at a rather high frequency, which is of interest for selection within the Carora breed because of the negative association of this variant with the synthesis of the specific protein. From a cheese-making point of view, this variant is associated with improved milk-clotting parameters but is negatively associated with cheese ripening. Thus, milk protein typing should be routinely carried out in the breed, with particular emphasis on using a DNA test to

  20. Salt-specific stability and denaturation of a short salt-bridge-forming alpha-helix.

    PubMed

    Dzubiella, Joachim

    2008-10-22

    The structure of a single alanine-based Ace-AEAAAKEAAAKA-Nme peptide in explicit aqueous electrolyte solutions (NaCl, KCl, NaI, and KF) at large salt concentrations (3-4 M) is investigated using approximately 1 mus molecular dynamics (MD) computer simulations. The peptide displays 71% alpha-helical structure without salt and destabilizes with the addition of NaCl in agreement with experiments of a somewhat longer version. It is mainly stabilized by direct and indirect (" i + 4")EK salt bridges between the Lys and Glu side chains and a concomitant backbone shielding mechanism. NaI is found to be a stronger denaturant than NaCl, while the potassium salts hardly show influence. Investigation of the molecular structures reveals that consistent with recent experiments Na (+) has a much stronger affinity to side chain carboxylates and backbone carbonyls than K (+), thereby weakening salt bridges and secondary structure hydrogen bonds. At the same time, the large I (-) has a considerable affinity to the nonpolar alanine in line with recent observations of a large propensity of I (-) to adsorb to simple hydrophobes, and thereby "assists" Na (+) in its destabilizing action. In the denatured states of the peptide, novel long-lived (10-20 ns) "loop" configurations are observed in which single Na (+) ions and water molecules are hydrogen-bonded to multiple backbone carbonyls. In an attempt to analyze the denaturation behavior within the preferential interaction formalism, we find indeed that for the strongest denaturant, NaI, the protein is least hydrated. Additionally, a possible indication for protein denaturation might be a preferential solvation of the peptide backbone by the destabilizing cosolute (sodium). The mechanisms found in this work may be of general importance to understand salt effects on protein secondary structure stability.

  1. High-resolution Lyman-alpha filtergrams of the sun

    NASA Technical Reports Server (NTRS)

    Bonnet, R. M.; Decaudin, M.; Bruner, E. C., Jr.; Acton, L. W.; Brown, W. A.

    1980-01-01

    The results of an experiment, conducted jointly by the Lockheed Palo Alto Research Laboratory and the Laboratoire de Physique Stellaire et Planetaire du CNRS, which investigated the transition-region plasma and the geometry of coronal active regions, in relation to models of the high-temperature layers, are presented. A Black Brant rocket was used to obtain 1-arc sec resolution L-alpha pictures of the sun, which revealed small scale features not seen previously at this wavelength, that delineate the geometry of the magnetic field in the chromosphere and in the corona. It is concluded that these observations might provide a new way of observing the upper chromosphere and corona, and that they provide direct evidence of the inhomogeneous character of the chromosphere and of the dominant role of the magnetic field

  2. Alpha storage regime in high temperature sub-ignited D-T tokamaks

    SciTech Connect

    Zweben, S.J.; Furth, H.P.; Mikkelsen, D.R.; Redi, M.H.; Strachan, J.D.

    1988-07-01

    Alpha particle parameters in sub-ignited D-T tokamaks like TFTR can be optimized in a high temperature ''alpha storage regime '' in which the alpha particle thermalization time /tau//sub ..cap alpha../ is long (approx.1.0 sec) and in which the alpha particle source rate S/sub ..cap alpha../ is enhanced due to a beam-target and beam-beam reactions (by a factor of approx.2-3). Near reactor-level alpha instability parameters ..beta../sub ..cap alpha../(0) approx. n/sub ..cap alpha../(0)/n/sub e/(O) approx. 1% are predicted by simulation codes when Q approx. 0.5-1, while present TFTR ''supershots'' already have ..beta../sub ..cap alpha../(O) approx. n/sub /alpha/(O)/n/sub e/(O) /approx/ 0.1-0.2%. Plasmas in this regime can be used to test theories of collective alpha instabilities for the first time, and can be used to provide a strong (but transient) alpha heating pulse. An experimental scenario to exploit this regime is described. 28 refs., 5 figs., 5 tabs.,

  3. Effect of cyclodextrins on alpha-chymotrypsin stability and loading in PLGA microspheres upon S/O/W encapsulation.

    PubMed

    Castellanos, Ingrid J; Flores, Giselle; Griebenow, Kai

    2006-04-01

    The potential of cyclodextrins to stabilize alpha-chymotrypsin upon encapsulation in Poly(lactic-co-glycolic) acid (PLGA) microspheres using a solid-in-oil-in-water (s/o/w) technique was investigated. Two cyclodextrins, hydroxyl-propyl-beta-cyclodextrin (HPbetaCD) and methyl-beta-cyclodextrin (MbetaCD), one insoluble and the other soluble in methylene chloride, were used. The results demonstrate that HPbetaCD failed to stabilize alpha-chymotrypsin upon encapsulation. Specifically, 19% of the protein was aggregated and the specific activity of the enzyme was reduced to ca. 50% of that prior to encapsulation. In contrast, MbetaCD significantly decreased the formation of aggregates to 3% and the retained specific activity of the enzyme was approximately 90%. The co-lyophilization of alpha-chymotrypsin with MbetaCD prior to encapsulation was a requisite to preserve the protein stability in microspheres. Furthermore, MbetaCD prevented the loss of protein during the preparation of microspheres and the encapsulation efficiency was improved to 90%. Release experiments showed the use of MbetaCD modified the release profile: the burst release decreased from 54% (in the absence of the excipient) to 36%. The results suggest that MbetaCD might be a suitable excipient to improve protein stability in s/o/w encapsulation procedures.

  4. 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.

  5. Flexible amorphous metal films with high stability

    NASA Astrophysics Data System (ADS)

    Liu, M.; Cao, C. R.; Lu, Y. M.; Wang, W. H.; Bai, H. Y.

    2017-01-01

    We report the formation of amorphous Cu50Zr50 films with a large-area of more than 100 cm2. The films were fabricated by ion beam assisted deposition with a slow deposition rate at moderate temperature. The amorphous films have markedly enhanced thermal stability, excellent flexibility, and high reflectivity with atomic level smoothness. The multifunctional properties of the amorphous films are favorites in the promising applications of smart skin or wearable devices. The method of preparing highly stable amorphous metal films by tuning the deposition rate instead of deposition temperature could pave a way for exploring amorphous metal films with unique properties.

  6. 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

  7. 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.

  8. The stability studies and in vitro hepatic microsomal metabolism of some alpha-phenyl-N-substituted nitrones in rats.

    PubMed

    Bulut, Gülen; Oktav, Mehmet; Ulgen, Mert

    2004-01-01

    Nitrones are a very important class of synthetic chemicals as synthetic intermediates, antioxidant agents, and metabolic oxidation products of secondary amines and imines used drug, food, cosmetic and printing industry. In the present study, the stability experiments and in vitro metabolism studies using rat microsomal preparations fortified with NADPH were carried out using three different alpha-phenyl-N-substituted nitrones ie alpha-phenyl-N-tert-butylnitrone (PTBN), alpha-(2,6-dichlorophenyl)-N-phenylnitrone (DCPPN) and alpha-phenyl-N-adamantanylnitrone (PADN). The separation of these compounds from the potential degradation, isomerization and metabolic products were performed using a reverse phase HPLC system with a diodearray uv detection. Following stability experiments at 37 degrees C using methanolic nitrone solutions, it was observed that PTBN produced trace amounts of benzaldehyde and the corresponding amide. DCPPN also produced trace amounts of amide. After 12 hours, the amount of the amide significantly increased. PADN produced trace amount of benzaldehyde but not any amide. The proposed compounds were incubated with rat microsomal preparations fortified with NADPH, extracted into dichloromethane (DCM) and finally evaporated under nitrogen in the dark conditions. PTBN was metabolized into corresponding amide whereas DCPPN and PADN did not. With all of the substrates, the corresponding aldehydes are observed with both test and control tubes using denaturated microsomes and without co-factors.

  9. One-dimensional {alpha}-MnO{sub 2}: Trapping chemistry of tunnel structures, structural stability, and magnetic transitions

    SciTech Connect

    Li Liping; Pan Yinzhen; Chen Lijuan; Li Guangshe

    2007-10-15

    Highly crystalline one-dimensional (1D) {alpha}-MnO{sub 2} nanostructures were synthesized by a hydrothermal method. All samples were characterized by X-ray diffraction, transmission electron microscope, thermogravimetric and differential scanning calorimeter, and infrared spectroscopy. During the formation reactions, the tunnel structure of 1D {alpha}-MnO{sub 2} was simultaneously modified by NH{sub 4}{sup +} species and water molecules. The amount of NH{sub 4}{sup +} species that were trapped in the tunnels is almost independent on the reaction temperature, while the total water content increased with the reaction temperature. The average diameter of {alpha}-MnO{sub 2} nanorods increased from 9.2 to 16.5 nm when the reaction temperature increased from 140 to 220 deg. C. 1D {alpha}-MnO{sub 2} was destabilized by a subsequent high-temperature treatment in air, which is accompanied by a structural transformation to 1D Mn{sub 2}O{sub 3} of a cubic structure. At low temperatures, all 1D {alpha}-MnO{sub 2} nanorods showed two magnetic transitions that were characterized by a decreased Neel temperature with rod diameter reduction. According to the effective magnetic moments experimentally measured, Mn ions presented in the nanorods were determined to be in a mixed valency of high spin state Mn{sup 4+}/Mn{sup 3+}. - Graphical abstract: Highly crystalline one-dimensional (1D) {alpha}-MnO{sub 2} nanostructures were achieved to have tunnel structures modified by NH{sub 4}{sup +} species and water molecules. By tuning the diameters. 1D {alpha}-MnO{sub 2} showed two magnetic transition as indicated by hump and kink peaks at low temperatures. Mn ions presented in 1D {alpha}-MnO{sub 2} were determined to be in a mixed valency of high spin state Mn{sup 4+}/Mn{sup 3+}.

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

    PubMed Central

    2016-01-01

    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

  11. Direct high-resolution alpha spectrometry from nuclear fuel particles in an outdoor air sample.

    PubMed

    Pöllänen, R; Siiskonen, T

    2008-01-01

    The potential use of direct high-resolution alpha spectrometry to identify the presence of transactinium elements in air samples is illustrated in the case when alpha-particle-emitting radionuclides are incorporated in nuclear fuel particles. Alpha particle energy spectra are generated through Monte Carlo simulations assuming a nuclide composition similar to RBMK (Chernobyl) nuclear fuel. The major alpha-particle-emitting radionuclides, in terms of activity, are 242Cm, 239Pu and 240Pu. The characteristics of the alpha peaks are determined by fuel particle properties as well as the type of the air filter. It is shown that direct alpha spectrometry can be readily applied to membrane filter samples containing nuclear fuel particles when rapid nuclide identification is of relevance. However, the development of a novel spectrum analysis code is a prerequisite for unfolding complex alpha spectra.

  12. 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.

  13. High activity of alpha-glycerophosphate oxidation by human placental mitochondria.

    PubMed

    Swierczyński, J; Scislowski, P; Aleksandrowicz, Z

    1976-03-11

    Human term placental mitochondria oxidize alpha-glycerophosphate at an unusually high rate as compared to other substrates. The apparent Km both for oxidation and alpha-glycerophosphate dehydrogenase (EC 1.1.99.5) activity of DL-alpha glycerophosphate determined in a medium containing 2mM EDTA and 5 mM MgSO4 was approx. 0.7 mM. EDTA inhibited the alpha-glycerophosphate oxidation if the later was used at low concentrations. A subsequent addition of MgSO4 or CaCl2 restored the original activity. EDTA had no effect on mitochondrial respiration at high concentration of alpha-glycerophosphate. Possible physiological role of relatively high activity of human placental mitochondrial alpha-glycerophosphate dehydrogenase is discussed.

  14. Monte Carlo studies of folding, dynamics, and stability in alpha-helices.

    PubMed

    Shental-Bechor, Dalit; Kirca, Safak; Ben-Tal, Nir; Haliloglu, Turkan

    2005-04-01

    Folding simulations of polyalanine peptides were carried out using an off-lattice Monte Carlo simulation technique. The peptide was represented as a chain of residues, each of which contains two interaction sites: one corresponding to the C(alpha) atom and the other to the side chain. A statistical potential was used to describe the interaction between these sites. The preferred conformations of the peptide chain on the energy surface, starting from several initial conditions, were searched by perturbations on its generalized coordinates with the Metropolis criterion. We observed that, at low temperatures, the effective energy was low and the helix content high. The calculated helix propagation (s) and nucleation (sigma) parameters of the Zimm-Bragg model were in reasonable agreement with the empirical data. Exploration of the energy surface of the alanine-based peptides (AAQAA)(3) and AAAAA(AAARA)(3)A demonstrated that their behavior is similar to that of polyalanine, in regard to their effective energy, helix content, and the temperature-dependence of their helicity. In contrast, stable secondary structures were not observed for (Gly)(20) at similar temperatures, which is consistent with the nonfolder nature of this peptide. The fluctuations in the slowest dynamics mode, which describe the elastic behavior of the chain, showed that as the temperature decreases, the polyalanine peptides become stiffer and retain conformations with higher helix content. Clustering of conformations during the folding phase implied that polyalanine folds into a helix through fewer numbers of intermediate conformations as the temperature decreases.

  15. Comparison of the wild-type alpha-amylase and its variant enzymes in Bacillus amyloliquefaciens in activity and thermal stability, and insights into engineering the thermal stability of bacillus alpha-amylase.

    PubMed

    Lee, Seunjae; Mouri, Yoshiki; Minoda, Masashi; Oneda, Hiroshi; Inouye, Kuniyo

    2006-06-01

    The starch hydrolysis activity and thermal stability of Bacillus amyloliquefaciens alpha-amylase (wild-type enzyme or WT) and its variant enzymes, designated as M77, M111, and 21B, were compared. All have an optimal pH at around 6, as well as almost the same reaction rates and Km and kcat values. The optimal temperature in the absence of Ca2+ ions is 60 degrees C for WT and M77 and 40 degrees C for M111 and 21B. Those of M111 and 21B rose to 50-60 degrees C upon the addition of 5 mM CaCl2, while those of WT and M77 did not change. The dissociation constants Kd for Ca2+ to WT and M77 are much lower than those of M111 and 21B. Asp233 in WT is replaced by Asn in M111 and 21B, while it is retained in M77, suggesting that Asp233 is involved in the thermal stability of the enzyme through Ca2+ ion binding. These findings provide insight into engineering the thermal stability of B. amyloliquefaciens alpha-amylase, which would be useful for its applications in the baking industry and in glucose manufacturing.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The smectic C*-alpha (SmCα*) 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 SmCα* commonly shows only very narrow phase temperature range of a few degree Celsius. To broaden the SmCα* 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 SmCα* 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.

  19. Effect immunization with highly purified alpha- and beta-toxins on staphylococcal mastitis in rabbits.

    PubMed

    Adlam, C; Ward, P D; McCartney, A C; Arbuthnott, J P; Thorley, C M

    1977-08-01

    Experiments were carried out to determine whether immunization of female rabbits with highly purified staphylococcal alpha- or beta-toxins would protect them against intramammary challenge with staphylococci. High circulating anti-alpha-toxin titers reduced the lethal hemorrhagic edematous form of the disease ("blue-breast") produced by strains BB and Compton 201 to a localized chronic abscess form. No such protection was afforded by high anti-beta-toxin titers. Immunization with alpha- or beta-toxins produced no change in the clinical picture of the disease produced by CN.6708, a strain of Staphylococcus responsible for a natural outbreak of abscess-type rabbit mastitis. From these experiments it would appear that alpha-toxin is a key antigen in the blue-breast form of rabbit mastitis. Since the abscess form of the disease was not prevented by immunization with either alpha- or beta-toxin, other virulence factors must be acting to produce this more localized disease.

  20. 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.

  1. Untranslated region-dependent exclusive expression of high-sensitivity subforms of alpha4beta2 and alpha3beta2 nicotinic acetylcholine receptors.

    PubMed

    Briggs, Clark A; Gubbins, Earl J; Marks, Michael J; Putman, C Brent; Thimmapaya, Rama; Meyer, Michael D; Surowy, Carol S

    2006-07-01

    alpha4beta2 nicotinic acetylcholine receptors (nAChRs) are recognized as the principal nicotine binding site in brain. Recombinant alpha4beta2 nAChR demonstrate biphasic concentration-response relationships with low- and high-EC50 components. This study shows that untranslated regions (UTR) can influence expression of high-sensitivity subforms of alpha4beta2 and alpha3beta2 nAChR. Oocytes injected with alpha4 and beta2 RNA lacking UTR expressed biphasic concentration-response relationships for acetylcholine with high-sensitivity EC50 values of 0.5 to 2.5 microM (14-24% of the population) and low-sensitivity EC50 values of 110 to 180 microM (76-86%). In contrast, message with UTR expressed exclusively the high-sensitivity alpha4beta2 nAChR subform with an acetylcholine EC50 value of 2.2 microM. Additional studies revealed pharmacological differences between high- and low-sensitivity alpha4beta2 subforms. Whereas the antagonists dihydro-beta-erythroidine (IC50 of 3-6 nM) and methyllycaconitine (IC50 of 40-135 nM) were not selective between high- and low-sensitivity alpha4beta2, chlorisondamine, mecamylamine, and d-tubocurarine were, respectively, 100-, 8-, and 5-fold selective for the alpha4beta2 subform with low sensitivity to acetylcholine. Conversely, agonists that selectively activated the high-sensitivity alpha4beta2 subform with respect to efficacy as well as potency were identified. Furthermore, two of these agonists were shown to activate mouse brain alpha4beta2 as well as the ferret high-sensitivity alpha4beta2 expressed in Xenopus laevis oocytes. With the use of UTR-containing RNA, exclusive expression of a novel high-sensitivity alpha3beta2 nAChR was also achieved. These studies 1) provide further evidence for the existence of multiple subforms of alpha4beta2 nAChR, 2) extend that to alpha3beta2 nAChR, 3) demonstrate UTR influence on beta2-containing nAChR properties, and 4) reveal compounds that interact with alpha4beta2 in a subform-selective manner.

  2. Mammoth hair: stability of alpha-keratin structure and constituent proteins.

    PubMed

    Gillespie, J M

    1970-12-04

    Hair from a woolly mammoth (Mammuthus primigenius, age about 32,000 years) retains the ordered structure characteristic of alpha-keratins, but the proteins of this hair differ in composition from and are smaller than similar proteins isolated from other keratins, for example, elephant hair. It is suggested that these changes have been caused by limited proteolysis.

  3. Influence of enrofloxacin administration and alpha-tocopheryl acetate supplemented diets on oxidative stability of broiler tissues.

    PubMed

    Carreras, I; Castellari, M; García Regueiro, J A; Guerrero, L; Esteve-Garcia, E; Sárraga, C

    2004-05-01

    The objective of this study was to assess the oxidative stability and presence of antibiotic residues in tissues of broilers fed diets supplemented with alpha-tocopheryl acetate and treated with enrofloxacin. The activities of antioxidant enzymes and antibiotic concentrations in chicken breast, leg, and liver were determined. Iron-induced TBA-reactive substances (TBARS) and vitamin E were evaluated in muscles. The antioxidant effectiveness of vitamin E was reflected by TBARS values being lower in antioxidant-supplemented treatments than in the other dietary groups. On the other hand, antioxidant enzyme activities were not substantially affected by dietary treatments. The concentration of enrofloxacin in tissues was considerable, even after withdrawal 12 d before slaughter. Contrary to the findings in previous studies, enrofloxacin was not extensively metabolized to ciprofloxacin. Supplementation of the diet with 100 mg/kg of alpha-tocopheryl acetate did not have a significant effect on the level of antibiotic found in breast muscle samples. When comparing treatments without antibiotic withdrawal time, alpha-tocopheryl acetate supplementation led to a significant decrease in enrofloxacin level in leg and liver samples. These results showed that mutual interactions between different molecules could modify the drug residues in the tissue, which should be taken into account when considering the drug administration and the establishment of a correct withdrawal time.

  4. 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

  5. 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.

  6. 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.

  7. Role of disulfide bridges in the activity and stability of a cold-active alpha-amylase.

    PubMed

    Siddiqui, Khawar Sohail; Poljak, Anne; Guilhaus, Michael; Feller, Georges; D'Amico, Salvino; Gerday, Charles; Cavicchioli, Ricardo

    2005-09-01

    The cold-adapted alpha-amylase from Pseudoalteromonas haloplanktis unfolds reversibly and cooperatively according to a two-state mechanism at 30 degrees C and unfolds reversibly and sequentially with two transitions at temperatures below 12 degrees C. To examine the role of the four disulfide bridges in activity and conformational stability of the enzyme, the eight cysteine residues were reduced with beta-mercaptoethanol or chemically modified using iodoacetamide or iodoacetic acid. Matrix-assisted laser desorption-time of flight mass spectrometry analysis confirmed that all of the cysteines were modified. The iodoacetamide-modified enzyme reversibly folded/unfolded and retained approximately one-third of its activity. Removal of all disulfide bonds resulted in stabilization of the least stable region of the enzyme (including the active site), with a concomitant decrease in activity (increase in activation enthalpy). Disulfide bond removal had a greater impact on enzyme activity than on stability (particularly the active-site region). The functional role of the disulfide bridges appears to be to prevent the active site from developing ionic interactions. Overall, the study demonstrated that none of the four disulfide bonds are important in stabilizing the native structure of enzyme, and instead, they appear to promote a localized destabilization to preserve activity.

  8. Adsorption of alpha-synuclein on lipid bilayers: modulating the structure and stability of protein assemblies.

    PubMed

    Haque, Farzin; Pandey, Anjan P; Cambrea, Lee R; Rochet, Jean-Christophe; Hovis, Jennifer S

    2010-03-25

    The interaction of alpha-synuclein with phospholipid membranes has been examined using supported lipid bilayers and epi-fluorescence microscopy. The membranes contained phosphatidylcholine (PC) and phosphatidic acid (PA), which mix at physiological pH. Upon protein adsorption, the lipids undergo fluid-fluid phase separation into PC-rich and PA-rich regions. The protein preferentially adsorbs to the PA-rich regions. The adsorption and subsequent aggregation of alpha-synuclein was probed by tuning several parameters: the charge on the lipids, the charge on the protein, and the screening environment. Conditions which promoted the greatest extent of adsorption resulted in structurally heterogeneous aggregates, while comparatively homogeneous aggregates were observed under conditions whereby adsorption did not occur as readily. Our observation that different alterations to the system lead to different degrees of aggregation and different aggregate structures poses a challenge for drug discovery. Namely, therapies aimed at neutralizing alpha-synuclein must target a broad range of potentially toxic, membrane-bound assemblies.

  9. 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.

  10. Targeting Alpha5 Beta1 Integrin to Prevent Metastatic Breast Cancer Cell Invasion: PhScN Target Site Definition and Plasma Stability

    DTIC Science & Technology

    2015-11-01

    Award Number: TITLE: “Targeting Alpha5 Beta1 Integrin to Prevent Metastatic Breast Cancer Cell Invasion: PhScN Target Site Definition and Plasma...SUBTITLE Targeting Alpha5 Beta1 Integrin to Prevent Metastatic Breast Cancer Cell Invasion: PhScN Target Site Definition and Plasma Stability 5a...desirable target. Our research tested definitively the hypothesis that both PHSCN and PhScN peptides inhibit α5β1 integrin fibronectin receptor

  11. Alpha Cyclotron Production Studies of the Alpha Emitter 211AT/211gPO for High-Let Metabolic Radiotherapy

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

    A series of high specific activity accelerator-produced radionuclides in no-carrier-added (NCA) form, for uses in metabolic radiotherapy and for PET, has been investigated and produced at JRC-Ispra Cyclotron Laboratory. In this study we present, in particular, the NCA 211At/211gPo (LET = 130 eV.nm-1, t1/2= 7.214 h), produced by 209Bi(α,2n) reaction, with internal spike of gamma emitter 210At (e.g. negligible amount of 210Po as radiotoxic long-lived impurity), for high-LET targeted radiotherapy and immunoradiotherapy. A selective radiochemical separation, based on liquid/liquid extraction, of At radionuclides from Bi target and Po impurities has been developed. High resolution gamma, X and alpha spectrometric techniques have been adopted for quality controls of different radiochemical fractions.

  12. 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.

  13. Kaposi's sarcoma-associated herpesvirus viral IFN regulatory factor 3 stabilizes hypoxia-inducible factor-1 alpha to induce vascular endothelial growth factor expression.

    PubMed

    Shin, Young C; Joo, Chul-Hyun; Gack, Michaela U; Lee, Hye-Ra; Jung, Jae U

    2008-03-15

    Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent associated with Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. Hypoxia-inducible factor-1 (HIF-1) is the master regulator of both developmental and pathologic angiogenesis, composed of an oxygen-sensitive alpha-subunit and a constitutively expressed beta-subunit. HIF-1 activity in tumors depends on the availability of the HIF-1 alpha subunit, the levels of which are increased under hypoxic conditions. Recent studies have shown that HIF-1 plays an important role in KSHV reactivation from latency and pathogenesis. Here, we report a novel mechanism by which KSHV activates HIF-1 activity. Specific interaction between KSHV viral IFN regulatory factor 3 (vIRF3) and the HIF-1 alpha subunit led to the HIF-1 alpha stabilization and transcriptional activation, which induced vascular endothelial growth factor expression and ultimately facilitated endothelial tube formation. Remarkably, the central domain of vIRF3, containing double alpha-helix motifs, was sufficient not only for binding to HIF-1 alpha but also for blocking its degradation in normoxic conditions. This indicates that KSHV has developed a unique mechanism to enhance HIF-1 alpha protein stability and transcriptional activity by incorporating a viral homologue of cellular IRF gene into its genome, which may contribute to viral pathogenesis.

  14. 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

  15. Study of the {beta}-{alpha} phase transformations of a Ti-64 sheet induced from a high-temperature {beta} state and a high-temperature {alpha} + {beta} state

    SciTech Connect

    Moustahfid, H.; Gey, N.; Humbert, M.; Philippe, M.J.

    1997-01-01

    The room-temperature {alpha} textures of Ti-64 sheets, inherited from the {beta}-{alpha} phase transformation of high-temperature {beta} textures of the material in the {beta} and {alpha} + {beta} fields, respectively, have been studied. The corresponding high-temperature {beta} textures were also determined by a method developed in their laboratory. The knowledge of the high-temperature {beta} textures allows discussions of the variant selections through transformation modeling. As a result, a variant selection occurs in the presence of the stable {alpha} grains of the {alpha} + {beta} field.

  16. 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).

  17. Alpha-beta chimeric oligo-DNA bearing intercalator-conjugated nucleobase inside the linker sequence remarkably improves thermal stability of an alternate-stranded triple helix.

    PubMed

    Zafrul Azam, A T M; Hasegawa, Minoru; Moriguchi, Tomohisa; Shinozuka, Kazuo

    2004-12-06

    Novel alpha-beta chimeric oligodeoxynucleotides bearing an intercalator-conjugated nucleobase located at the internal 4-nt linker region were synthesized, and their triplex-stabilizing property was examined. The triple helical DNA formed between the modified chimera DNA and double-stranded DNA exhibited remarkable thermal stability; however, the position of the intercalator-conjugated nucleobase had little influence on the stability. Among the examined, modified chimera DNA bearing the two intercalator-conjugated nucleobases at adjacent positions exhibited the highest stability.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. Unusual Thermal Stability of High-Entropy Alloy Amorphous Structure

    DTIC Science & Technology

    2012-06-20

    1    REPORT Unusual Thermal Stability of High - Entropy Alloy Amorphous Structure Basic research for AOARD 114009 Award No. FA2386-11-1...stability of high - entropy alloy amorphous structure 5a. CONTRACT NUMBER FA23861114009 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Jien-Wei...at least 3 h. If substrate effect could be eliminated, the crystallization temperature would be higher. 15. SUBJECT TERMS high entropy alloys 16

  5. The human alpha defensin HD5 neutralizes JC polyomavirus infection by reducing endoplasmic reticulum traffic and stabilizing the viral capsid.

    PubMed

    Zins, Stephen R; Nelson, Christian D S; Maginnis, Melissa S; Banerjee, Rahul; O'Hara, Bethany A; Atwood, Walter J

    2014-01-01

    Progressive multifocal leukoencephalopathy (PML) is a fatal disease with limited treatment options, both clinically and in the research pipeline. Potential therapies would target and neutralize its etiologic agent, JC polyomavirus (JCPyV). The innate immune response to JCPyV infection has not been studied, and little is known about the initial host response to polyomavirus infection. This study examined the ability of a human alpha defensin, HD5, to neutralize JCPyV infection in human fetal glial cells. We show that HD5, by binding to the virion, blocks infection. The JCPyV-HD5 complexes bind to and enter host cells but are reduced in their ability to reach the endoplasmic reticulum (ER), where virions are normally uncoated. Furthermore, HD5 binding to the virion stabilizes the capsid and prevents genome release. Our results show that HD5 neutralizes JCPyV infection at an early postentry step in the viral life cycle by stabilizing the viral capsid and disrupting JCPyV trafficking. This study provides a naturally occurring platform for developing antivirals to treat PML and also expands on the known capabilities of human defensins.

  6. The Human Alpha Defensin HD5 Neutralizes JC Polyomavirus Infection by Reducing Endoplasmic Reticulum Traffic and Stabilizing the Viral Capsid

    PubMed Central

    Zins, Stephen R.; Nelson, Christian D. S.; Maginnis, Melissa S.; Banerjee, Rahul; O'Hara, Bethany A.

    2014-01-01

    Progressive multifocal leukoencephalopathy (PML) is a fatal disease with limited treatment options, both clinically and in the research pipeline. Potential therapies would target and neutralize its etiologic agent, JC polyomavirus (JCPyV). The innate immune response to JCPyV infection has not been studied, and little is known about the initial host response to polyomavirus infection. This study examined the ability of a human alpha defensin, HD5, to neutralize JCPyV infection in human fetal glial cells. We show that HD5, by binding to the virion, blocks infection. The JCPyV-HD5 complexes bind to and enter host cells but are reduced in their ability to reach the endoplasmic reticulum (ER), where virions are normally uncoated. Furthermore, HD5 binding to the virion stabilizes the capsid and prevents genome release. Our results show that HD5 neutralizes JCPyV infection at an early postentry step in the viral life cycle by stabilizing the viral capsid and disrupting JCPyV trafficking. This study provides a naturally occurring platform for developing antivirals to treat PML and also expands on the known capabilities of human defensins. PMID:24198413

  7. Ballooning mode stability of elongated high-beta tokamaks

    NASA Astrophysics Data System (ADS)

    Mauel, Michael E.

    1987-12-01

    The variational principle derived by Choe and Freidberg [Phys. Fluids 29, 1766 (1986)] and used to estimate the geometry of high-beta tokamak equilibria is extended to include elongation. Ballooning mode stability is then investigated, illustrating the influence of elongation on local and global stability.

  8. 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.

  9. Bacterial cell wall products increases stabilization of HIF-1 alpha in an oligodendrocyte cell line preconditioned by cobalt chloride or desferrioxamine.

    PubMed

    Yao, Song-yi; Soutto, Mohammed; Sriram, Subramaniam

    2008-08-30

    We examined the effect of lipopolysaccharide (LPS) or lipotechoic acid (LTA) on the regulation of hypoxia inducible factor (HIF-1) alpha on the MO3.13 cells, a human oligodendroglial cell line. Our study shows that MO3.13 cells express the toll like receptors (TLR's) but do not increase cellular levels of HIF-1 alpha following exposure to bacterial cell wall products. When MO3.13 cells were preconditioned by desferrioxamine (DFO) or cobalt chloride (CoCl(2)) and then treated with either LPS or LTA, HIF-1 alpha levels were higher than that induced by DFO or CoCl(2) alone. The increase in HIF-1 alpha was due to increased protein stability that was mediated by activation of the ERK-MAP kinase pathway.

  10. K(alpha) x-ray emission characterization of 100 Hz, 15 mJ femtosecond laser system with high contrast ratio.

    PubMed

    Fourmaux, S; Serbanescu, C; Kincaid, R E; Krol, A; Kieffer, J C

    2008-12-12

    We report K(alpha) x-ray production with a high energy (110 mJ per pulse at 800 nm before compression/15 mJ at 400 nm after compression), high repetition rate (100 Hz), and high pulse contrast (better than 10(-9) at 400 nm) laser system. To develop laser-based x-ray sources for biomedical imaging requires to use high-energy and high-power ultra-fast laser system where compression is achieved under vacuum. Using this type of laser system, we demonstrate long-term stability of the x-ray yield, conversion efficiency higher than 1.5 x 10(-5) with a Mo target, and the x-ray spot size close to the optical focal spot. This high-repetition K(alpha) x-ray source can be very useful for x-ray phase-contrast imaging.

  11. Characterization of long and stable de novo single alpha-helix domains provides novel insight into their stability

    PubMed Central

    Wolny, Marcin; Batchelor, Matthew; Bartlett, Gail J.; Baker, Emily G.; Kurzawa, Marta; Knight, Peter J.; Dougan, Lorna; Woolfson, Derek N.; Paci, Emanuele; Peckham, Michelle

    2017-01-01

    Naturally-occurring single α-helices (SAHs), are rich in Arg (R), Glu (E) and Lys (K) residues, and stabilized by multiple salt bridges. Understanding how salt bridges promote their stability is challenging as SAHs are long and their sequences highly variable. Thus, we designed and tested simple de novo 98-residue polypeptides containing 7-residue repeats (AEEEXXX, where X is K or R) expected to promote salt-bridge formation between Glu and Lys/Arg. Lys-rich sequences (EK3 (AEEEKKK) and EK2R1 (AEEEKRK)) both form SAHs, of which EK2R1 is more helical and thermo-stable suggesting Arg increases stability. Substituting Lys with Arg (or vice versa) in the naturally-occurring myosin-6 SAH similarly increased (or decreased) its stability. However, Arg-rich de novo sequences (ER3 (AEEERRR) and EK1R2 (AEEEKRR)) aggregated. Combining a PDB analysis with molecular modelling provides a rational explanation, demonstrating that Glu and Arg form salt bridges more commonly, utilize a wider range of rotamer conformations, and are more dynamic than Glu–Lys. This promiscuous nature of Arg helps explain the increased propensity of de novo Arg-rich SAHs to aggregate. Importantly, the specific K:R ratio is likely to be important in determining helical stability in de novo and naturally-occurring polypeptides, giving new insight into how single α-helices are stabilized. PMID:28287151

  12. High-performance liquid chromatographic determination of the glycoalkaloids alpha-solanine and alpha-chaconine in 12 commercial varieties of Mexican potato.

    PubMed

    Sotelo, A; Serrano, B

    2000-06-01

    The glycoalkaloid content in 12 commercial varieties of Mexican potatoes was measured by HPLC in both the peel and the flesh of the potato. The principal glycoalkaloids alpha-solanine and alpha-chaconine were present in higher concentration in the peel than in the flesh of all varieties. The main alkaloid in the peel of the potatoes was alpha-chaconine and comprised about 65-71% of the total glycoalkaloids. The high concentration of alpha-chaconine in peel, which is more toxic than alpha-solanine, gives more protection to the tuber against predators. The total alkaloids in the peel of Alpha, Juanita, Michoacan, Norteña, Rosita, and Tollocan varieties were higher than the limit recommended for food safety. However, the peel represents less than 10% of the total tuber in most of the varieties. The total alkaloids contained in the peel of Atzimba, Lopez, Marciana, Montsama, Murca, and Puebla was lower than the limits recommended for food safety. The glycoalkaloid content in the boiled peeled potatoes was less than 9 mg/100 g but in Alpha, Montsama, and Puebla varieties, both glycoalkaloids were absent. According to the results, the consumption of the 12 commercial varieties of Mexican potatoes does not represent any danger to human health.

  13. 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.

  14. Development of a high resolution alpha spectrometer using a magnetic calorimeter

    NASA Astrophysics Data System (ADS)

    Yoon, W. S.; Kang, C. S.; Kim, S. R.; Kim, G. B.; Lee, H. J.; Lee, M. K.; Lee, J. H.; So, J. H.; Kim, Y. H.

    2015-06-01

    We have developed a high resolution alpha spectrometer with a magnetic calorimeter. The operating principle of the detector is the calorimetric measurement of the temperature increase from particle absorption in a gold foil absorber at milli-Kelvin temperatures. A magnetic calorimeter made of gold doped with erbium on a superconducting meander pickup coil was used to accurately measure the temperature change, thereby acting as an ultra-sensitive thermometer. The detector demonstrated 1.2 keV FWHM equivalent resolution in alpha particle detection with an 241Am source. Many peaks were observed in the low-energy region from the absorption of low-energy X-rays, gamma rays, and conversion electrons. An energy resolution of 400 eV FWHM was achieved for 60 keV gamma rays that were measured with the alpha particles. Possible applications of such high resolution detectors are discussed.

  15. Alpha(2)-macroglobulin levels are high in adult patients with congenital antithrombin deficiency.

    PubMed

    Tripodi, A; Chantarangkul, V; De Stefano, V; Mannucci, P

    2000-04-15

    Antithrombin is responsible for about 80% of the progressive inhibitory activity of thrombin in human plasma. The role of other protease inhibitors known to inhibit thrombin is not completely clarified. However, their contribution may become relevant when antithrombin is low. We elected to investigate adult patients with congenital antithrombin deficiency to assess the concentration of other naturally occurring thrombin inhibitors such as alpha(2)-macroglobulin, alpha(1)-antitrypsin, heparin cofactor II, and C(1)-inhibitor. The study included 59 patients with congenital antithrombin deficiency with and without a previous history of thrombosis, together with an equal number of control subjects matched for age and sex. Statistically significant differences (patients vs. controls) were observed only for alpha(2)-macroglobulin (i.e., 120 vs. 102%, p<0.01). Further analysis of antithrombin-deficient carriers with and without a past history of thrombosis showed that alpha(2)-macroglobulin levels were higher than the 90th percentile of control distribution more often in asymptomatic than symptomatic men (odds ratio=0.04; confidence interval=0.003-0.60), but not in women (odds ratio=2.14; confidence interval=0.35-13.1). In conclusion, results from this cross sectional study showed that alpha(2)-macroglobulin levels were high in patients with congenital antithrombin deficiency. Furthermore, the high levels were found more often in asymptomatic than symptomatic men. Whether this increase provides protection against thrombosis should be evaluated in a prospective study.

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

    PubMed

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

    2012-09-26

    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.

  17. Stability of ricinine, abrine, and alpha-amanitin in finished tap ...

    EPA Pesticide Factsheets

    Journal Article Ricinine and abrine are potential indicators of drinking water contamination by the biotoxins ricin and abrin, respectively. Simultaneous detection of ricinine and abrine, along with α-amanitin, another potential biotoxin water contaminant, is reportable through the use of automated sample preparation via solid phase extraction and detection using liquid chromatography/tandem-mass spectrometry. Performance of the method was characterized over eight analytical batches with quality control samples analyzed over 10 days. For solutions of analytes prepared with appropriate preservatives, the minimum reporting level (MRL) was 0.50 μg/L for ricinine and abrine and 2.0 μg/L for α-amanitin. Among the analytes, the accuracy of the analysis ranged between 93 and 100% at concentrations of 1-2.5 x the MRL, with analytical precision ranging from 4 to 8%. Five drinking waters representing a range of water quality parameters and disinfection practices were fortified with the analytes and analyzed over a 28 day period to determine their storage stability in these waters. Ricinine was observed to be stable for 28 days in all tap waters. The analytical signal decreased within 5 hrs of sample preparation for abrine and μ-amanitin in some waters, but afterwards, remained stable for 28 days. The magnitude of the decrease correlated with common water quality parameters potentially related to sorption of contaminants onto dissolved and colloidal components within

  18. Variations in resting frontal alpha asymmetry between high- and low-neuroticism females across the menstrual cycle.

    PubMed

    Huang, Yamei; Zhou, Renlai; Cui, Hong; Wu, Mengying; Wang, Qingguo; Zhao, Yan; Liu, Yanfeng

    2015-02-01

    Resting frontal alpha asymmetry measures the relative activation intensity across the left and right frontal regions that represent emotional experience. Here, the focus is on levels of alpha asymmetry between high- and low-neuroticism females across the menstrual cycle. Resting alpha asymmetry in healthy females who scored high or low on neuroticism was assessed during the menstrual phase, the late follicular phase, and the midlate luteal phase. High-neuroticism females exhibited lower relative left prefrontal activity than did low-neuroticism females during the midlate luteal phase, as indexed by alpha1 and alphaTotal asymmetry scores at the prefrontal electrode positions (FP1/2 ). EEG results demonstrate that the resting frontal alpha asymmetry of high- and low-neuroticism females was moderated by the menstrual cycle, and high-neuroticism females should pay particular attention to their emotional experience during the midlate luteal phase.

  19. Macroscopic stability of high β MAST plasmas

    NASA Astrophysics Data System (ADS)

    Chapman, I. T.; Cooper, W. A.; Graves, J. P.; Gryaznevich, M. P.; Hastie, R. J.; Hender, T. C.; Howell, D. F.; Hua, M.-D.; Huysmans, G. T. A.; Keeling, D. L.; Liu, Y. Q.; Meyer, H. F.; Michael, C. A.; Pinches, S. D.; Saarelma, S.; Sabbagh, S. A.; MAST Team

    2011-07-01

    The high-beta capability of the spherical tokamak, coupled with a suite of world-leading diagnostics on MAST, has facilitated significant improvements in the understanding of performance-limiting core instabilities in high performance plasmas. For instance, the newly installed motional Stark effect diagnostic, with radial resolution <25 mm, has enabled detailed study of saturated long-lived modes in hybrid scenarios. Similarly, the upgraded Thomson scattering system, with radial resolution <10 mm and the possibility of temporal resolution of 1 µs, has allowed detailed analysis of the density and temperature profiles during transient activity in the plasma, such as at a sawtooth crash. High resolution charge exchange recombination spectroscopy provided measurement of rotation braking induced by both applied magnetic fields and by magnetohydrodynamic (MHD) instabilities, allowing tests of neoclassical toroidal viscosity theory predictions. Finally, MAST is also equipped with internal and external coils that allow non-axisymmetric fields to be applied for active MHD spectroscopy of instabilities near the no-wall beta limit. MAST has been able to operate above the pressure at which the resonant field amplification is observed to strongly increase. In order to access such high pressures, the resistive wall mode must be damped, and so numerical modelling has focused on assessing the kinetic damping of the mode and its nonlinear interaction with other instabilities. The enhanced understanding of the physical mechanisms driving deleterious MHD activity given by these leading-edge capabilities has provided guidance to optimize operating scenarios for improved plasma performance.

  20. 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.

  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. Stability of xenon oxides at high pressures.

    PubMed

    Zhu, Qiang; Jung, Daniel Y; Oganov, Artem R; Glass, Colin W; Gatti, Carlo; Lyakhov, Andriy O

    2013-01-01

    Xenon, which is quite inert under ambient conditions, may become reactive under pressure. The possibility of the formation of stable xenon oxides and silicates in the interior of the Earth could explain the atmospheric missing xenon paradox. Using an ab initio evolutionary algorithm, we predict the existence of thermodynamically stable Xe-O compounds at high pressures (XeO, XeO(2) and XeO(3) become stable at pressures above 83, 102 and 114 GPa, respectively). Our calculations indicate large charge transfer in these oxides, suggesting that large electronegativity difference and high pressure are the key factors favouring the formation of xenon compounds. However, xenon compounds cannot exist in the Earth's mantle: xenon oxides are unstable in equilibrium with the metallic iron occurring in the lower mantle, and xenon silicates are predicted to decompose spontaneously at all mantle pressures (<136 GPa). However, it is possible that xenon atoms may be retained at defects in mantle silicates and oxides.

  3. 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.

  4. Sintered alpha silicon carbide ceramics for high temperature structural application - Status review and recent developments

    NASA Technical Reports Server (NTRS)

    Storm, R. S.; Boecker, W. D. G.; Mcmurtry, C. H.; Srinivasan, M.

    1985-01-01

    The physical properties of sintered alpha silicon carbide are reviewed, including the effect of oxidation at high temperatures. Net shape fabricated components are described which have undergone extensive testing in heat engine applications. Properties of an SiC/TiB2 composite material, which has significantly improved fracture toughness, are presented.

  5. Ulyssis Observations of Differential Streaming Between Protons and Alphas at High Latitudes

    NASA Technical Reports Server (NTRS)

    Neugebauer, M.; Goldstein, B. E.; Smith, E. J.; Feldman, W. C.

    1995-01-01

    Reported are observations from the Ulysses SWOOPS experiment which provided measurements of the differential streaming between protons and alphas as a function of heliocentric distance and latitude. The data reported are of observations for those periods when Ulysses sampled only the flows from the solar polar coronal holes. All of the high-latitude results differ from the outbound, in-ecliptic data.

  6. H-alpha profile observations of a limb flare with high temporal resolution

    NASA Astrophysics Data System (ADS)

    Graeter, M.

    1990-12-01

    The impulsive phase of a 1N/M2.0 limb flare on September 8, 1988 was observed in H-alpha with high temporal resolution. With an imaging spectrograph line profiles have been acquired every 2.3 sec. The temporal evolution in the blue and red wing has been correlated with hard X-ray data from HXRBS. It is shown that a prominent spike in the blue wing of H-alpha was delayed with respect to the corresponding hard X-ray burst by 7-8 sec. With the exception of the spike in the blue wing of H-alpha, the temporal development of the line profile is compatible with the predictions for nonthermal electron heating during the impulsive phase.

  7. 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.

  8. [Development of highly stereoselective reactions utilizing heteroatoms--asymmetric synthesis of alpha-substituted serines].

    PubMed

    Sano, S

    2000-01-01

    This article reviews the efficient methods for diastereoselective and enantioselective syntheses of alpha-substituted serines. A newly designed bislactim ether, ethyl (5S)- or (5R)-3,6-diethoxy-2,5-dihydro-5-isopropyl-2-pyrazinecarboxylate, was treated with base or Lewis acid-tertiary amine to generate an enolate or enaminate (imine anion, metalloenamine). Alkylation or aldol-type reaction with the resultant enolate or enaminate proceeded in a highly diastereoselective manner to give the corresponding alkylated or aldol products, respectively. Reduction of these products with diisobutylaluminum hydride (DIBAL) followed by hydrolysis with hydrochloric acid afforded the desirable alpha-substituted serines. The enantioselective aldol-type reaction of an achiral bislactim ether, ethyl 3,6-diethoxy-2,5-dihydro-2-pyrazinecarboxylate, was also investigated by employing Sn(OSO2CF3)2-triethylamine in the presence of an external chiral ligand, (--)-sparteine. Not only a stoichiometric amount, but also a catalytic amount of (--)-sparteine promoted the highly enantioselective aldol-type reactions. Interestingly, the stereoselective outcome of the Sn(II)-mediated reaction differed from that of the Mg(II)-mediated one in the aldol-type reaction of the bislactim ethers with aliphatic aldehydes. On the other hand, chemoenzymatic synthesis of enantiomerically pure alpha-substituted serines must also be a convenient and useful procedure. Porcine liver esterase (PLE) or rabbit liver esterase (RLE) catalyzed hydrolysis of the pro-S ester group of diethyl alpha-alkyl-alpha-(benzyloxycarbonylamino)malonates to afford (R)-ethyl alpha-alkyl-alpha-(benzyloxycarbonylamino)malonates each in excellent enantiomeric excess. Enantiodivergent reductions of these acid esters readily proceeded to furnish both the corresponding enantiomeric alpha-substituted serines. Finally, the application of these methodologies mentioned above to a total synthesis of ISP-I (a potent immunosuppressive principle in

  9. 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.

  10. Both microtubule-stabilizing and microtubule-destabilizing drugs inhibit hypoxia-inducible factor-1alpha accumulation and activity by disrupting microtubule function.

    PubMed

    Escuin, Daniel; Kline, Erik R; Giannakakou, Paraskevi

    2005-10-01

    We have recently identified a mechanistic link between disruption of the microtubule cytoskeleton and inhibition of tumor angiogenesis via the hypoxia-inducible factor-1 (HIF-1) pathway. Based on this model, we hypothesized that other microtubule-targeting drugs may have a similar effect on HIF-1alpha. To test that hypothesis, we studied the effects of different clinically relevant microtubule-disrupting agents, including taxotere, epothilone B, discodermolide, vincristine, 2-methoxyestradiol, and colchicine. In all cases, HIF-1alpha protein, but not mRNA, was down-regulated in a drug dose-dependent manner. In addition, HIF-1alpha transcriptional activity was also inhibited by all drugs tested. To further examine whether these effects were dependent on microtubule network disruption, we tested the ability of epothilone B to inhibit HIF-1alpha protein in the human ovarian cancer cell line 1A9 and its beta-tubulin mutant epothilone-resistant subclone 1A9/A8. Our data showed that epothilone B treatment down-regulated HIF-1alpha protein in the parental 1A9 cells but had no effect in the resistant 1A9/A8 cells. These observations were confirmed by confocal microscopy, which showed impaired nuclear accumulation of HIF-1alpha in parental 1A9 cells at epothilone B concentrations that induced extensive microtubule stabilization. In contrast, epothilone B treatment had no effect on either microtubules or HIF-1alpha nuclear accumulation in the resistant 1A9/A8 cells. Furthermore, epothilone B inhibited HIF-1 transcriptional activity in 1A9 cells, as evidenced by a hypoxia response element-luciferase reporter assay, but had no effect on HIF-1 activity in the resistant 1A9/A8 cells. These data directly link beta-tubulin drug binding with HIF-1alpha protein inhibition. Our results further provide a strong rationale for testing taxanes and epothilones in clinical trials targeting HIF-1 in cancer patients.

  11. 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.

  12. Fluorescence and CD spectroscopic analysis of the alpha-chymotrypsin stabilization by the ionic liquid, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide.

    PubMed

    De Diego, Teresa; Lozano, Pedro; Gmouh, Said; Vaultier, Michel; Iborra, José L

    2004-12-30

    The stability of alpha-chymotrypsin in the ionic liquid, 1-ethyl-3-methyl-imidizolium bis[(trifluoromethyl)sulfonyl]amide ([emim][NTf2]), was studied at 30 and 50 degrees C and compared with the stability in other liquid media, such as water, 3 M sorbitol, and 1-propanol. The kinetic analysis of the enzyme stability pointed to the clear denaturative effect of 1-propanol, while both 3M sorbitol and [emim][NTf2] displayed a strong stabilizing power. For the first time, it is shown that enzyme stabilization by ionic liquids seems to be related to the associated structural changes of the protein that can be observed by differential scanning calorimetry (DSC) and fluorescence and circular dichroism (CD). The [emim][NTf2] enhanced both the melting temperature and heat capacity of the enzyme compared to the other media assayed. The fluorescence spectra clearly showed the ability of [emim][NTf2] to compact the native structural conformation of alpha-chymotrypsin, preventing the usual thermal unfolding which occurs in other media. Changes in the secondary structure of this beta/beta protein, as quantified by the CD spectra, pointed to the great enhancement (up 40% with respect to that in water) of beta-strands in the presence of the ionic liquid, which reflects its stabilization power.

  13. 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

  14. 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

  15. 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.

  16. Functional characterization of mongoose nicotinic acetylcholine receptor alpha-subunit: resistance to alpha-bungarotoxin and high sensitivity to acetylcholine.

    PubMed

    Asher, O; Lupu-Meiri, M; Jensen, B S; Paperna, T; Fuchs, S; Oron, Y

    1998-07-24

    The mongoose is resistant to snake neurotoxins. The mongoose muscle nicotinic acetylcholine receptor (AChR) alpha-subunit contains a number of mutations in the ligand-binding domain and exhibits poor binding of alpha-bungarotoxin (alpha-BTX). We characterized the functional properties of a hybrid (alpha-mongoose/beta gamma delta-rat) AChR. Hybrid AChRs, expressed in Xenopus oocytes, respond to acetylcholine with depolarizing current, the mean maximal amplitude of which was greater than that mediated by the rat AChR. The IC50 of alpha-BTX to the hybrid AChR was 200-fold greater than that of the rat, suggesting much lower affinity for the toxin. Hybrid AChRs exhibited an apparent higher rate of desensitization and higher affinity for ACh (EC50 1.3 vs. 23.3 microM for the rat AChR). Hence, changes in the ligand-binding domain of AChR not only affect the binding properties of the receptor, but also result in marked changes in the characteristics of the current.

  17. 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).

  18. [Effects of packaging on the stability of vitamin E in peach kernels stored at high temperature].

    PubMed

    Li, Chengwen; Sun, Meixia; Miao, Mingsan

    2005-02-01

    Peach kernels with three different kinds of packaging, including routine, vacuum and edible film, were put into an accelerated test in order to study the effects of packaging on the stability of vitamin E, gamma-, alpha-, and delta-tocopherol. The result indicated that among the three kinds of packaging, the stability of vitamin E in the samples with vacuum packaging was the best, and with routine packaging was the worst. And for the samples with the same kind of packaging, the stabilities of gamma-, alpha- and delta-tocophero decreased one by one.

  19. Stabilization of weakly charged microparticles using highly charged nanoparticles.

    PubMed

    Herman, David; Walz, John Y

    2013-05-21

    An experimental study was performed to understand the ability of highly charged nanoparticles to stabilize a dispersion of weakly charged microspheres. The experiments involved adding either anionic (sulfate) or cationic (amidine) latex nanoparticles to dispersions of micrometer-sized silica particles near the silica isoelectric point (IEP). Although both types of nanoparticles increased the zeta potential of the silica microspheres above the value at which dispersions containing only silica spheres remained stable, only with the amidine nanoparticles was stability obtained. Adsorption tests with flat silica slides showed that the amidine nanoparticles deposited in much greater numbers onto the silica, producing multilayer coverage with adsorbed particle densities that were roughly three times that obtained with the sulfate nanoparticles. A model calculating the DLVO interaction between the silica spheres in which the adsorbed nanoparticle layers were treated as a continuous film with dielectric properties between those of polystyrene and water predicted stability for both systems. It is hypothesized that the relatively low adsorption of the sulfate nanoparticles (fractional surface coverages ≤ 25%) led to patches of bare silica on the microspheres that could align during interaction due to Brownian motion. These results indicate that highly charged nanoparticles can be effective stabilizers provided the level of adsorption is sufficiently high. It was also found that the zeta potential alone is not a sufficient parameter for predicting stability of these binary systems.

  20. Revisit of alpha-chitin crystal structure using high resolution X-ray diffraction data.

    PubMed

    Sikorski, Pawel; Hori, Ritsuko; Wada, Masahisa

    2009-05-11

    High resolution synchrotron X-ray fiber diffraction data recorded from crab tendon chitin have been used to describe the crystal structure of alpha-chitin. Crystal structures at 100 and 300 K have been solved using restrained crystallographic refinement against diffraction intensities measured from the fiber diffraction patterns. The unit cell contains two polymer chains in a 2(1) helix conformation and in the antiparallel orientation. The best agreement between predicated and observed X-ray diffraction intensities is obtained for a model that includes two distinctive conformations of C6-O6 hydroxymethl group. Those conformations are different from what is proposed in the generally accepted alpha-chitin crystal structure (J. Mol. Biol. 1978, 120, 167-181). Based on refined positions of the O6 atoms, a network of hydrogen bonds involving O6 is proposed. This network of hydrogen bonds can explain the main features of the polarized FTIR spectra of alpha-chitin and sheds some light on the origin of splitting of the amide I band observed on alpha-chitin IR spectra.

  1. 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.

  2. 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.

  3. Alpha Blockers

    MedlinePlus

    ... conditions such as high blood pressure and benign prostatic hyperplasia. Find out more about this class of medication. ... these conditions: High blood pressure Enlarged prostate (benign prostatic hyperplasia) Though alpha blockers are commonly used to treat ...

  4. Alpha-ray spectrometry at high temperature by using a compound semiconductor detector.

    PubMed

    Ha, Jang Ho; Kim, Han Soo

    2013-11-01

    The use of conventional radiation detectors in harsh environments is limited by radiation damage to detector materials and by temperature constraints. We fabricated a wide-band gap semiconductor radiation detector based on silicon carbide. All the detector components were considered for an application in a high temperature environment like a nuclear reactor core. The radiation response, especially to alpha particles, was measured using an (241)Am source at variable operating voltages at room temperature in the air. The temperature on detector was controlled from 30°C to 250°C. The alpha-particle spectra were measured at zero bias operation. Even though the detector is operated at high temperature, the energy resolution as a function of temperature is almost constant within 3.5% deviation.

  5. Bioinspired, Mobile Robots With High Stability, Functionality and Low Cost

    DTIC Science & Technology

    2014-02-19

    MOBILE ROBOTS WITH HIGH STABILITY, FUNCTIONALITY AND LOW COST W911NF-11-1-0094 FINAL REPORT 2/15/11 – 9/30/13 THE HARVARD TEAM DARPA /DSO...ATTN: BAA 10-65 Dr. Gill Pratt 3701 North Fairfax Drive Arlington VA 22203-1714 Technical POC: Dr. Gill Pratt, DARPA /DSO Submission

  6. 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.

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

    PubMed

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

    2015-06-15

    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.

  8. 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.

  9. 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

  10. Highly regioselective hydrogenolysis of bis(alpha-methylbenzyl)amine derivatives affected by the trifluoromethyl substituent on the aromatic ring.

    PubMed

    Kanai, Masatomi; Yasumoto, Manabu; Kuriyama, Yokusu; Inomiya, Kenjin; Katsuhara, Yutaka; Higashiyama, Kimio; Ishii, Akihiro

    2003-04-03

    [reaction: see text] The highly regioselective hydrogenolysis of bis(alpha-methylbenzyl)amine derivatives proceeded with influence not from the electronic effect but from the steric effect of the trifluoromethyl substituent on the aromatic ring to provide a practical asymmetric synthesis of trifluoromethyl-substituted alpha-phenylethylamines.

  11. 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.

  12. 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.

  13. High Stability Optical Mount for Space Laser Applications

    NASA Astrophysics Data System (ADS)

    Mosciarello, P.; Di Carmine, E.

    2014-06-01

    In the frame of Atmospheric Lidar (ATLID) project, one of the active instruments foreseen to be boarded on the EarthCARE satellite, a high stability optical mount has been designed, developed and tested in order to fulfil the tight program requirements.A description of the design solution developed, manufactured and qualified for the most critical optical mount inside the PLH, located on the Laser Master Oscillator Plate (the laser resonance cavity), is presented. In order to minimize optical mount mass and envelope, the developed solution foresees a glued interface (I/F) between the mechanical support and the mirror.A collection of stability results obtained on the optical mount breadboards is also presented, including a description of environmental tests performed and the way to assess the mirror stability after each environmental test, as well as the acceptance criteria derived in order to establish the flight worthiness of the manufactured and assembled hardware.

  14. Phase transformation and stabilization of a high strength austenite

    NASA Technical Reports Server (NTRS)

    Jin, S.; Huang, D.

    1976-01-01

    An investigation of the phase transformation and the austenite stabilization in a high strength austenite has been made. An Fe-29Ni-4.3Ti austenite age-hardened by gamma-prime (Ni3Ti) precipitates showed a further increase of strength after martensitic and reverse martensitic phase transformations. The stability of ausaged austenite as well as ausaged and transformation-strengthened austenite was improved significantly through an isothermal treatment at 500 C. The Ms temperature of the strengthened austenite was restored to nearly that of annealed austenite while the austenite was hardened to R(C) 41 through precipitation and phase transformations. The observed austenite stabilization is attributed to the formation of GP zones or short-range order of less than about 10A in size.

  15. Isolation of a highly specific ligand for the alpha 5 beta 1 integrin from a phage display library

    PubMed Central

    1994-01-01

    Our previous studies showed that the alpha 5 beta 1 integrin selects cysteine pair-containing RGD peptides from a phage display library based on a random hexapeptide. We have therefore searched for more selective peptides for this integrin using a larger phage display library, where heptapeptides are flanked by cysteine residues, thus making the inserts potentially cyclic. Most of the phage sequences that bound to alpha 5 beta 1 (69 of 125) contained the RGD motif. Some of the heptapeptides contained an NGR motif. As the NGR sequence occurs in the cell-binding region of the fibronectin molecule, this sequence could contribute to the specific recognition of fibronectin by alpha 5 beta 1. Selection for high affinity peptides for alpha 5 beta 1 surprisingly yielded a sequence RRETAWA that does not bear obvious resemblance to known integrin ligand sequences. The synthetic cyclic peptide GACRRETAWACGA (*CRRETAWAC*) was a potent inhibitor of alpha 5 beta 1-mediated cell attachment to fibronectin. This peptide is nearly specific for the alpha 5 beta 1 integrin, because much higher concentrations were needed to inhibit the alpha v beta 1 integrin, and there was no effect on alpha v beta 3- and alpha v beta 5-mediated cell attachment to vitronectin. The peptide also did not bind to the alpha IIb beta 3 integrin. *CRRETAWAC* appears to interact with the same or an overlapping binding site in alpha 5 beta 1 as RGD, because cell attachment to *CRRETAWAC* coated on plastic was divalent cation dependent and could be blocked by an RGD-containing peptide. These results reveal a novel binding specificity in the alpha 5 beta 1 integrin. PMID:7507494

  16. In silico analysis of the thermodynamic stability changes of psychrophilic and mesophilic alpha-amylases upon exhaustive single-site mutations.

    PubMed

    Gilis, Dimitri

    2006-01-01

    Identifying sequence modifications that distinguish psychrophilic from mesophilic proteins is important for designing enzymes with different thermodynamic stabilities and to understand the underlying mechanisms. The PoPMuSiC algorithm is used to introduce, in silico, all the single-site mutations in four mesophilic and one psychrophilic chloride-dependent alpha-amylases and to evaluate the changes in thermodynamic stability. The analysis of the distribution of the sequence positions that could be stabilized upon mutation shows a clear difference between the three domains of psychrophilic and mesophilic alpha-amylases. Most of the mutations stabilizing the psychrophilic enzyme are found in domains B and C, contrary to the mesophilic proteins where they are preferentially situated in the catalytic domain A. Moreover, the calculations show that the environment of some residues responsible for the activity of the psychrophilic protein has evolved to reinforce favorable interactions with these residues. In the second part, these results are exploited to propose rationally designed mutations that are predicted to confer to the psychrophilic enzyme mesophilic-like thermodynamic properties. Interestingly, most of the mutations found in domain C strengthen the interactions with domain A, in agreement with suggestions made on the basis of structural analyses. Although this study focuses on single-site mutations, the thermodynamic effects of the recommended mutations should be additive if the mutated residues are not close in space.

  17. Long-term treatment of tumor-operated mice with high doses of alpha-difluoromethylornithine.

    PubMed

    de Lustig, E S; Klein, S; Fuchs, A; Algranati, I D

    1986-01-01

    Mice inoculated subcutaneously with a mammary adenocarcinoma M3cell suspension and submitted 10 to 15 days later to the surgical removal of primary tumors have been chosen in our laboratory as the experimental model to study the effect of several drugs on metastasis spreading. A 90-day treatment of tumor-operated mice with high doses of alpha-difluoromethylornithine showed, in addition to a marked decrease of lung metastases, several side effects including a loss of body weight, a delay of surgical wound healing and a reduced number of megakaryocytes in bone marrow. The measurement of ceruloplasmin in serum has indicated that treated animals contained increased levels of this oxidase activity in spite of the polyamine depletion caused by alpha-difluoromethylornithine. These results rule out a direct correlation between ceruloplasmin activity and polyamine concentration.

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  1. 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.

  2. 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}.

  3. 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.

  4. 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.

  5. 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.

  6. Numerical simulation of the flow about an F-18 aircraft in the high-alpha regime

    NASA Technical Reports Server (NTRS)

    Murman, Scott M.; Rizk, Yehia M.

    1994-01-01

    The current research is aimed at developing and extending numerical methods to accurately predict the high Reynolds number flow about the NASA F-18 HARV at large angles of attack. The resulting codes are validated by comparison of the numerical results with in-flight aerodynamic measurements and flow visualization obtained on the HARV. Further, computations have been used to provide an analysis and numerical optimization of a pneumatic slot blowing concept, and a mechanical strake concept, for use as potential forebody flow control devices in improving high-alpha maneuverability.

  7. 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.

  8. High-Velocity Ly(Alpha) Emission from SMR 1987A

    NASA Technical Reports Server (NTRS)

    Michael, Eli; McCray, Richard; Borkowski, Kazimierz J.; Pun, Chu S. J.; Sonneborn, George

    1998-01-01

    The high-velocity Ly(Alpha) emission from SN 1987A observed with the Space Telescope Imaging Spectrograph (STIS) evidently comes from a reverse shock formed where the outer envelope of SN 1987A strikes ionized gas inside the inner circumstellar ring. The observations can be explained by a simple kinematic model, in which the Ly(Alpha) emission comes from hydrogen atoms with radial velocity approximately 15,000 km s(exp -1) crossing a reverse shock in the shape of a slightly prolate ellipsoid with equatorial radius 4.8 x 10(exp 17) cm or approximately 80% of the distance to the inner surface of the inner ring. N v double Lambda 1239, 1243 emission, if present, has a net luminosity approximately less than 30% times that of the Ly(Alpha) emission. Future STIS observations should enable us to predict the time of impact with the inner ring and to determine unambiguously whether or not N v emission is present. These observations will offer a unique opportunity to probe the structure of SN 1987A's circumstellar environment and the hydrodynamics and kinetics of very fast shocks.

  9. 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.

  10. Alpha-1-antitrypsin deficiency. High prevalence in the St. Louis area determined by direct population screening.

    PubMed

    Silverman, E K; Miletich, J P; Pierce, J A; Sherman, L A; Endicott, S K; Broze, G J; Campbell, E J

    1989-10-01

    Considerable attention has been focused upon alpha-1-antitrypsin deficiency because of the insights into the pathogenesis of human pulmonary emphysema that may derive from study of deficient subjects, and because of evolving therapeutic strategies that may slow the progression of lung disease in affected persons. We have applied an automated immunoassay for alpha-1-antitrypsin to plasma samples from 20,000 blood donors. Seven PI Z antitrypsin-deficient persons were identified and confirmed; this is more than twice the number predicted from previous estimates of the Z allele frequency in the St. Louis area. Five of the subjects were further evaluated. We anticipate that this assay, if utilized to screen large populations, could identify many alpha-1-antitrypsin-deficient persons for study of the natural history of lung and liver disease associated with the deficiency. These subjects would be potential candidates for early intervention strategies to prevent the development of lung disease. The surprisingly high prevalence of deficient persons indicates that direct screening is the best method for prevalence estimation of genetic disorders.

  11. Direct-scanning alpha spectrometer for americium and plutonium contamination on highly-enriched uranium surfaces

    SciTech Connect

    Ward, W.C.; Martinez, H.E.; Abeyta, C.L.; Morgan, A.N.; Nelson, T.O.

    1997-04-02

    Trace Pu{sup 239} and Am{sup 241} contamination on a surface whose alpha count is dominated by U{sup 235} and U{sup 234} decay has been successfully quantified by counting swipes in external alpha spectroscopy chambers. The swipe process, however, is labor intensive and subject to uncertainties in the swiping process as well as degraded spectral resolution due to the presence of the swipe material. A multichannel instrument for automated in situ measurements of interior and exterior contamination has been developed which incorporates a rotary table, 13 fixed ion-implanted silicon detectors, and spectroscopy electronics. Custom software was written to allow alpha spectrometer to function as a virtual instrument in the LabView environment. This system gives improved speed and resolution as well as a complete log of the location of areas of high surface contamination, a feature not practical to obtain by other methods, and one which opens the possibility of long term studies such as Pu outgrowth evaluation employing the instrument. The authors present performance data as well as system integration, calibration, control, and dynamic geometric efficiency calculations related to the design of this and next generation systems.

  12. 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.

  13. Determination of alpha-solanine and alpha-chaconine in potatoes by high-performance thin-layer chromatography/densitometry.

    PubMed

    Bodart, P; Kabengera, C; Noirfalise, A; Hubert, P; Angenot, L

    2000-01-01

    A high-performance thin-layer chromatographic (HPTLC) method was used to determine the glycoalkaloids alpha-solanine and alpha-chaconine in potatoes. Alpha-solanine and alpha-chaconine are extracted from dehydrated potatoes with boiling methanol-acetic acid (95 + 5, v/v). The analytes are separated on a Silica Gel 60 F254 HPTLC plate by a saturated mixture of dichloromethane-methanol-water-concentrated ammonium hydroxide (70 + 30 + 4 + 0.4, v/v), which is used for vertical development of the plate up to a distance of 85 mm. For visualization, the plate is dipped 3 times into a modified Carr-Price reagent, 20% (w/v) antimony(III) chloride in acetic acid-dichloromethane (1 + 3, v/v), and subsequently heated on a hot plate at 105 degrees C for 5 min. The glycoalkaloids all appear as red chromatographic zones on a colorless background. Densitometric quantification is performed at 507 nm by reflectance scanning. After determination of the appropriate response function, the proposed method was validated. Good results with respect to linearity, accuracy, and precision were obtained in the concentration range studied.

  14. 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.

  15. 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.

  16. 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.

  17. The progressive development of structure and stability during the equilibrium folding of the alpha subunit of tryptophan synthase from Escherichia coli.

    PubMed Central

    Gualfetti, P. J.; Bilsel, O.; Matthews, C. R.

    1999-01-01

    The urea-induced equilibrium unfolding of the alpha subunit of tryptophan synthase (alphaTS), a single domain alpha/beta barrel protein, displays a stable intermediate at approximately 3.2 M urea when monitored by absorbance and circular dichroism (CD) spectroscopy (Matthews CR, Crisanti MM, 1981, Biochemistry 20:784-792). The same experiment, monitored by one-dimensional proton NMR, shows another cooperative process between 5 and 9 M urea that involves His92 (Saab-Rincón G et al., 1993, Biochemistry 32:13,981-13,990). To further test and quantify the implied four-state model, N <--> I1 <--> I2 <--> U, the urea-induced equilibrium unfolding process was followed by tyrosine fluorescence total intensity, tyrosine fluorescence anisotropy and far-UV CD. All three techniques resolve the four stable states, and the transitions between them when the FL total intensity and CD spectroscopy data were analyzed by the singular value decomposition method. Relative to U, the stabilities of the N, I1, and I2 states are 15.4, 9.4, and 4.9 kcal mol(-1), respectively. I2 partially buries one or more of the seven tyrosines with a noticeable restriction of their motion; it also recovers approximately 6% of the native CD signal. This intermediate, which is known to be stabilized by the hydrophobic effect, appears to reflect the early coalescence of nonpolar side chains without significant organization of the backbone. I1 recovers an additional 43% of the CD signal, further sequesters tyrosine residues in nonpolar environments, and restricts their motion to an extent similar to N. The progressive development of a higher order structure as the denaturant concentration decreases implies a monotonic contraction in the ensemble of conformations that represent the U, I2, I1, and N states of alphaTS. PMID:10452606

  18. 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.

  19. Energy stability in a high average power FEL

    SciTech Connect

    Merminga, L.; Bisognano, J.J.

    1995-12-31

    Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M{sub 56}, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents determined. Design strategies to increase the instability threshold are discussed and the high average power FEL proposed for construction at CEBAF is used as an example.

  20. Adverse effects of high doses of intravenous alpha lipoic Acid on liver mitochondria.

    PubMed

    Vigil, Michael; Berkson, Burton M; Garcia, Ana Patricia

    2014-01-01

    Alpha lipoic acid (ALA, thioctic acid), among other actions, is an essential coenzyme in the conversion of pyruvate to acetyl co-enzyme A. Therefore, it is necessary for the production of energy for aerobic organisms. Scientists have found that it can be used medically to help regenerate liver tissue, reverse the complications of diabetes mellitus, slow or stop the growth of cancer cells, and chelate heavy metals, among other actions. In this article, the authors describe the cellular mitochondrial damage from excessively high doses of this beneficial agent.

  1. Activity of nAChRs containing alpha9 subunits modulates synapse stabilization via bidirectional signaling programs.

    PubMed

    Murthy, Vidya; Taranda, Julián; Elgoyhen, A Belén; Vetter, Douglas E

    2009-12-01

    Although the synaptogenic program for cholinergic synapses of the neuromuscular junction is well known, little is known of the identity or dynamic expression patterns of proteins involved in non-neuromuscular nicotinic synapse development. We have previously demonstrated abnormal presynaptic terminal morphology following loss of nicotinic acetylcholine receptor (nAChR) alpha9 subunit expression in adult cochleae. However, the molecular mechanisms underlying these changes have remained obscure. To better understand synapse formation and the role of cholinergic activity in the synaptogenesis of the inner ear, we exploit the nAChR alpha9 subunit null mouse. In this mouse, functional acetylcholine (ACh) neurotransmission to the hair cells is completely silenced. Results demonstrate a premature, effusive innervation to the synaptic pole of the outer hair cells in alpha9 null mice coinciding with delayed expression of cell adhesion proteins during the period of effusive contact. Collapse of the ectopic innervation coincides with an age-related hyperexpression pattern in the null mice. In addition, we document changes in expression of presynaptic vesicle recycling/trafficking machinery in the alpha9 null mice that suggests a bidirectional information flow between the target of the neural innervation (the hair cells) and the presynaptic terminal that is modified by hair cell nAChR activity. Loss of nAChR activity may alter transcriptional activity, as CREB binding protein expression is decreased coincident with the increased expression of N-Cadherin in the adult alpha9 null mice. Finally, by using mice expressing the nondesensitizing alpha9 L9'T point mutant nAChR subunit, we show that increased nAChR activity drives synaptic hyperinnervation.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

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

    DOE PAGES

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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.

  8. Stability of high cell density brewery fermentations during serial repitching.

    PubMed

    Verbelen, Pieter J; Dekoninck, Tinne M L; Van Mulders, Sebastiaan E; Saerens, Sofie M G; Delvaux, Filip; Delvaux, Freddy R

    2009-11-01

    The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e. higher inoculum size). However, the decreased yeast net growth observed in these high cell density brewery fermentations can adversely affect the physiological stability throughout subsequent yeast generations. Therefore, different O(2) conditions (wort aeration and yeast preoxygenation) were applied to high cell density fermentation and eight generations of fermentations were evaluated together with conventional fermentations. Freshly propagated high cell density populations adapted faster to the fermentative conditions than normal cell density populations. Preoxygenating the yeast was essential for the yeast physiological and beer flavor compound stability of high cell density fermentations during serial repitching. In contrast, the use of non-preoxygenated yeast resulted in inadequate growth which caused (1) insufficient yield of biomass to repitch all eight generations, (2) a 10% decrease in viability, (3) a moderate increase of yeast age, (4) and a dramatic increase of the unwanted flavor compounds acetaldehyde and total diacetyl during the sequence of fermentations. Therefore, to achieve sustainable high cell density fermentations throughout the economical valuable process of serial repitching, adequate yeast growth is essential.

  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

    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.

  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

    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.

  11. Stability of high-brilliance synchrotron radiation sources

    SciTech Connect

    Chattopadhyay, S.

    1989-12-01

    This paper discusses the following topics: characteristics of synchrotron radiation sources; stability of the orbits; orbit control; nonlinear dynamic stability; and coherent stability and control. 1 ref., 5 figs., 1 tab. (LSP)

  12. 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

  13. Interferon-alpha2a and 13-cis-retinoic acid with radiation treatment for high-grade glioma.

    PubMed Central

    Dillman, R. O.; Shea, W. M.; Tai, D. F.; Mahdavi, K.; Barth, N. M.; Kharkar, B. R.; Poor, M. M.; Church, C. K.; DePriest, C.

    2001-01-01

    Interferon-alpha (IFN-alpha) has been safely given concurrently with radiation therapy (RT) in treating gliomas. As single agents, both IFN-alpha and cis-retinoic acid (CRA) have produced objective tumor regressions in patients with recurrent gliomas. In vitro, IFN-alpha2a and CRA enhance radiation therapy effects on glioblastoma cells more than either agent alone. This trial was conducted to determine the clinical effects of IFN-alpha2a and CRA when given concurrently with radiation therapy to patients with high-grade glioma. Newly diagnosed patients with high-grade glioma received IFN-alpha2a at a dosage of 3 to 6 million IU s.c. 4 times a day for 3 days per week and 1 mg/kg CRA by mouth 4 times a day for 5 days per week during the delivery of partial brain radiation therapy at 180 cGy x 33 fractions for 5 days per week for a total of 59.4 Gy during the 7-week period. Use of the antiepileptic phenytoin was prohibited after observing that the combination of IFN-alpha2a, CRA, and phenytoin was associated with a high rate of dermatologic toxicity not seen in a previous study with concurrent IFN-alpha2a and radiation therapy. Forty patients (26 men and 14 women) with a median age of 60 (range, 19 to 81 years) were enrolled between August 1996 and October 1998. Histopathologic diagnoses were glioblastoma multiforme or grade 4 anaplastic astrocytoma in 36 patients, and grade 3 anaplastic astrocytoma in 4 patients. Only 4 patients (10%) underwent a gross total resection of tumor prior to this therapy; 50% were asymptomatic when treatment was initiated. The planned 7-week course of concurrent therapy was completed by 75% of patients; 30% completed the 16-week course of IFN-alpha and CRA alone. At a median follow-up of 36 months, there were 37 deaths, with a median overall survival of 9.3 months and a 1-year survival rate of 42%. There was no improvement in survival compared with a similar group of 19 patients treated with concurrent IFN-alpha2a and radiation therapy in a

  14. 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.

  15. Probing the Physical Properties of High-Redshift Lyman-Alpha Emitters with Spitzer

    NASA Astrophysics Data System (ADS)

    Finkelstein, Keely; Finkelstein, Steven; Rhoads, James E.; Malhotra, Sangeeta

    2015-08-01

    Abstract: Studies of Lyman Alpha emitting galaxies (LAEs) offer insight into an understanding of early galaxies and the build-up of galaxies at early times. To better understand these objects and constrain their stellar properties, we have observed a sample of 162 z=4.5 and 14 z=5.7 LAEs with deep Spitzer IRAC 3.6 and 4.5 micron imaging from the Spitzer Lyman Alpha Survey. This is by far the largest sample of high-redshift LAEs imaged with Spitzer, which probes rest-frame optical wavelengths at these redshifts, dramatically improving constraints on the stellar masses and star-formation rates. By fitting the spectral energy distributions of individual LAEs using ground-based optical, HST near-IR, and Spitzer mid-IR imaging, we show that our sample of LAEs has a wide range of stellar properties. For individual LAEs detected with IRAC, stellar mass ranges from 5x10^8 - 10^11 solar masses. In addition, we find a correlation between stellar mass and star formation rate (SFR), similar to trends measured at lower redshift (e.g. Noeske et al. 2007; Daddi et al. 2007). However for this sample of higher redshift LAEs, the LAE sequence is elevated compared to continuum-selected galaxies at the same redshift, meaning that for a given stellar mass, the LAEs tend to have higher star formation rates. However, a subset of massive LAEs sits on the continuum-selected galaxy trend, tentatively implying that there may be two mechanisms for Lyman alpha escape.

  16. Highly turbulent solutions of the Lagrangian-averaged Navier-Stokes alpha model and their large-eddy-simulation potential.

    PubMed

    Pietarila Graham, Jonathan; Holm, Darryl D; Mininni, Pablo D; Pouquet, Annick

    2007-11-01

    spectrum for large alpha. These small-scale features, however, do not preclude the LANS alpha model from reproducing correctly the intermittency properties of the high-Reynolds-number flow.

  17. 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.

  18. Stability of vocational interests among high school students.

    PubMed

    Mullis, R L; Mullis, A K; Gerwels, D

    1998-01-01

    The purpose of this study was to examine the stability of adolescents' career interests using the Strong-Campbell Interest Inventory (SCII). Students at a Midwestern high school were administered the SCII twice over a three-year period, and comparisons were made on Occupational Themes and Basic Interests. Significant differences in mean scores were found by gender and parental occupation, and these differences were relatively stable. The findings are discussed in relation to previous research and Holland's theory, and the implications are addressed.

  19. Pulse stabilization by high-order dispersion management

    NASA Astrophysics Data System (ADS)

    Moeser, J.; Gabitov, I.; Jones, C. K. R. T.

    2002-12-01

    The stabilizing effects of dispersion management (DM) at second and third order are studied for both single-channel and wavelength-division multiplexed (WDM) systems. We first derive a model for the slow evolution of a pulse in an optical fiber with high-order dispersion management (HODM). For single-channel systems, in contrast with conventional DM with constant third-order dispersion, this equation possesses a stable solution, the ground state for its associated Hamiltonian, which propagates nearly periodically under direct numerical simulation. Improved performance for WDM systems is also observed, as complicated pulse interactions, which can lead to undesirable effects such as frequency shift, are prevented by HODM.

  20. 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.

  1. Damped Ly alpha absorbers at high redshift: Large disks or galactic building blocks?

    NASA Technical Reports Server (NTRS)

    Haehnelt, Martin G.; Steinmetz, Matthias; Rauch, Michael

    1997-01-01

    The nature of the physical structures giving rise to damped Lyman alpha absorption systems (DLAS) at high redshifts is investigated. The proposal that rapidly rotating large disks are the only viable explanation for the observed asymmetric profiles of low ionization absorption lines is examined. Using hydrodynamic simulations of galaxy formation, it is demonstated that irregular protogalactic clumps can reproduce the observed velocity width distribution and asymmetries of the absorption profiles equally well. The velocity broadening in the simulated clumps is due to a mixture of rotation, random motions, infall and merging. The observed velocity width correlates with the virial velocity for the dark matter halo of the forming protogalactic clump. The typical virial velocity of the halos required to lead to the DLAS population is approximately 100 km/s. It is concluded that the evidence that DLAS at high redshift are related to large, rapidly rotating disks, is not compelling.

  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. Association of Tenebrio molitor L. alpha-amylase with two protein inhibitors--one monomeric, one dimeric--from wheat flour. Differential scanning calorimetric comparison of heat stabilities.

    PubMed

    Silano, V; Zahnley, J C

    1978-03-28

    Thermal stabilization resulting from protein . protein association between two protein inhibitors (coded as 0.19, a dimer, and 0.28, a monomer) from wheat flour and the alpha-amylase from Tenebrio molitor L. (yellow mealworm) larvae was investigated by differential scanning calorimetry (heating rate 10 degrees C/min). Thermograms (plots of heat flow vs. temperature) for the two inhibitors showed broad endothermic peaks with the same extrema (denaturation temperatures) at 93 degrees C, and equal, small enthalpies of denaturation (2 cal/g). The amylase produced a sharp endotherm at 70.5 degrees C, but a larger enthalpy change on denaturation (6 cal/g). The amylase . inhibitor complexes differed in thermal stability, but both showed significant stabilization relative to free enzyme. The complex formed with monomeric inhibitor 0.28 showed a higher denaturation temperature (85.0 degrees C) than that formed with dimeric inhibitor 0.19 (80.5 degrees C). This order of stabilization agrees with the relative affinities of the inhibitors for the amylase. These thermograms are consistent with previous results which indicated that 1 mol of amylase binds 1 mol of inhibitor 0.19.

  4. 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.

  5. Dissociation between PGC-1alpha and GLUT-4 expression in skeletal muscle of rats fed a high-fat diet.

    PubMed

    Higashida, Kazuhiko; Higuchi, Mitsuru; Terada, Shin

    2009-12-01

    It has recently been reported that a 4-wk high-fat diet gradually increases skeletal muscle peroxisome proliferator activated receptor (PPAR) gamma coactivator-1alpha (PGC-1alpha) protein content, which has been suggested to regulate GLUT-4 gene transcription. However, it has not been reported that a high-fat diet enhances GLUT-4 mRNA expression and protein content in skeletal muscle, suggesting that an increase in PGC-1alpha protein content is not sufficient to induce muscle GLUT-4 biogenesis in a high-fat fed animal. Therefore, we first evaluated the relationship between PGC-1alpha and GLUT-4 expression in skeletal muscle of rats fed a high-fat diet for 4 wk. The PGC-1alpha protein content in rat epitrochlearis muscle significantly increased by twofold after the 4-wk high-fat diet feeding. However, the high-fat diet had no effect on GLUT-4 protein content and induced a 30% decrease in GLUT-4 mRNA expression in rat skeletal muscle (p<0.05). To clarify the mechanism by which a high-fat diet downregulates GLUT-4 mRNA expression, we next examined the effect of PPARdelta activation, which is known to occur in response to a high-fat diet, on GLUT-4 mRNA expression in L6 myotubes. Incubation with 500 nM GW501516 (PPARdelta activator) for 24 h significantly decreased GLUT-4 mRNA in L6 myotubes. Taken together, these findings suggest that a high-fat diet downregulates GLUT-4 mRNA, possibly through the activation of PPARdelta, despite an increase in PGC-1alpha protein content in rat skeletal muscle, and that a posttranscriptional regulatory mechanism maintains GLUT-4 protein content in skeletal muscle of rats fed a high-fat diet.

  6. 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

  7. 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

  8. 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

  9. 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

  10. Hard alpha-keratin degradation inside a tissue under high flux X-ray synchrotron micro-beam: a multi-scale time-resolved study.

    PubMed

    Leccia, Emilie; Gourrier, Aurélien; Doucet, Jean; Briki, Fatma

    2010-04-01

    X-rays interact strongly with biological organisms. Synchrotron radiation sources deliver very intense X-ray photon fluxes within micro- or submicro cross-section beams, resulting in doses larger than the MGy. The relevance of synchrotron radiation analyses of biological materials is therefore questionable since such doses, million times higher than the ones used in radiotherapy, can cause huge damages in tissues, with regard to not only DNA, but also proteic and lipid organizations. Very few data concerning the effect of very high X-ray doses in tissues are available in the literature. We present here an analysis of the structural phenomena which occur when the model tissue of human hair is irradiated by a synchrotron X-ray micro-beam. The choice of hair is supported by its hierarchical and partially ordered keratin structure which can be analysed inside the tissue by X-ray diffraction. To assess the damages caused by hard X-ray micro-beams (1 microm(2) cross-section), short exposure time scattering SAXS/WAXS patterns have been recorded at beamline ID13 (ESRF) after various irradiation times. Various modifications of the scattering patterns are observed, they provide fine insight of the radiation damages at various hierarchical levels and also unexpectedly provide information about the stability of the various hierarchical structural levels. It appears that the molecular level, i.e. the alpha helices which are stabilized by hydrogen bonds and the alpha-helical coiled coils which are stabilized by hydrophobic interactions, is more sensitive to radiation than the supramolecular architecture of the keratin filament and the filament packing within the keratin associated proteins matrix, which is stabilized by disulphide bonds.

  11. First results from the Goddard High-Resolution Spectrograph - The chromosphere of Alpha Tauri

    NASA Technical Reports Server (NTRS)

    Carpenter, Kenneth G.; Robinson, Richard D.; Wahlgren, Glenn M.; Ake, Thomas B.; Ebbets, Dennis C.

    1991-01-01

    The K5 III star Alpha Tau was observed with the Goddard High Resolution Spectrograph on November 27, 1990 as part of the Science Assessment Program for the HST. The spectra show intersystem and permitted chromospheric emission lines of semiforbidden C II and Si II, Fe II, Fe I, Ni II, and Co II. Resolved profiles of the semiforbidden C II lines indicate a complex chromospheric turbulent velocity distribution with mean value of roughly 24 km/s, while their observed wavelengths indicate a 4 km/s downflow of the semiforbidden C II plasma. Twenty-five new emission lines have been found in the 2320-2370 A region, 17 of which have been identified with the aid of Skylab data obtained above the solar limb, including four lines from Co II (UV 8) and an Fe I (UV 12) line.

  12. 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.

  13. 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.

  14. 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.

  15. Role of deformation twins in static recrystallization kinetics of high-purity alpha titanium

    NASA Astrophysics Data System (ADS)

    Won, Jong Woo; Lee, Taekyung; Hong, Seong-Gu; Lee, Yongmoon; Lee, Jeong Hun; Lee, Chong Soo

    2016-11-01

    The importance of deformation twins in static recrystallization kinetics of high-purity alpha titanium was investigated by carrying out thermal annealing tests of deformed materials in combination with electron-backscatterdiffraction- based microstructural analysis. Prior to thermal annealing, the material was compressed to a true strain of 0.22 along three directions to introduce different twinning characteristics. Our results showed that deformation twins substantially promoted the static recrystallization process by deepening the microstructural inhomogeneity induced by the formation of twin boundaries and twinning-induced crystallographic lattice reorientation. Twin morphology was also observed to be important because it influenced the extent of microstructural inhomogeneity. Intersecting twin morphology, caused by the activation of multiple twin variants, was more effective than parallel twin morphology, caused by the activation of a single twin variant (or a twin variant pair), because it gave rise to more twin boundaries, more twin boundary junctions (intersections, triple junctions, etc.), and greater in-grain crystallographic orientation spread.

  16. Structural Stability and Functional Remodeling of High-Density Lipoproteins

    PubMed Central

    Gursky, Olga

    2015-01-01

    Lipoproteins are protein-lipid nanoparticles that transport lipids in circulation and are central in atherosclerosis and other disorders of lipid metabolism. Apolipoproteins form flexible structural scaffolds and important functional ligands on the particle surface and direct lipoprotein metabolism. Lipoproteins undergo multiple rounds of metabolic remodeling that is crucial to lipid transport. Important aspects of this remodeling, including apolipoprotein dissociation and particle fusion, are mimicked in thermal or chemical denaturation and are modulated by free energy barriers. Here we review our biophysical studies that revealed kinetic mechanism of lipoprotein stabilization and unraveled its structural basis. The main focus is on high-density lipoprotein (HDL). An inverse correlation between stability and functions of various HDLs in cholesterol transport suggests functional role of structural disorder. A mechanism for conformational adaptation of the major HDL proteins, apoA-I and apoA-II, to the increasing lipid load is proposed. Together, these studies help understand why HDL form discrete subclasses separated by kinetic barriers, which have distinct composition, conformation and functional properties. Understanding these properties may help improve HDL quality and develop novel therapies for cardiovascular disease. PMID:25749369

  17. Stability of shock waves in high temperature plasmas

    SciTech Connect

    Das, Madhusmita; Bhattacharya, Chandrani; Menon, S. V. G.

    2011-10-15

    The Dyakov-Kontorovich criteria for spontaneous emission of acoustic waves behind shock fronts are investigated for high temperature aluminum and beryllium plasmas. To this end, the Dyakov and critical stability parameters are calculated from Rankine-Hugoniot curves using a more realistic equation of state (EOS). The cold and ionic contributions to the EOS are obtained via scaled binding energy and mean field theory, respectively. A screened hydrogenic model, including l-splitting, is used to calculate the bound electron contribution to the electronic EOS. The free electron EOS is obtained from Fermi-Dirac statistics. Predictions of the model for ionization curves and shock Hugoniot are found to be in excellent agreement with available experimental and theoretical data. It is observed that the electronic EOS has significant effect on the stability of the planar shock front. While the shock is stable for low temperatures and pressures, instability sets in as temperature rises. The basic reason is ionization of electronic shells and consequent increase in electronic specific heat. The temperatures and densities of the unstable region correspond to those where electronic shells get ionized. With the correct modeling of bound electrons, we find that shock instability for Al occurs at a compression ratio {approx}5.4, contrary to the value {approx}3 reported in the literature. Free electrons generated in the ionization process carry energy from the shock front, thereby giving rise to spontaneously emitted waves, which decay the shock front.

  18. Stability boundaries for wrinkling in highly stretched elastic sheets

    NASA Astrophysics Data System (ADS)

    Li, Qingdu; Healey, Timothy J.

    2016-12-01

    We determine stability boundaries for the wrinkling of highly unidirectionally stretched, finely thin, rectangular elastic sheets. For a given fine thickness and length, a stability boundary here is a curve in the parameter plane, aspect ratio vs. the macroscopic strain; the values on one side of the boundary are associated with stable unwrinkled (flat) states, while stable wrinkled configurations correspond to all values on the other. In our recent work we demonstrated the importance of finite elasticity in the membrane part of such a model in order to capture the correct phenomena. Here we present and compare results for four distinct models: (i) the popular Föppl-von Kármán plate model (FvK), (ii) a correction of the latter, used in our earlier work, in which the approximate 2D Föppl strain tensor is replaced by the exact Green strain tensor, (iii) and (iv): effective 2D finite-elasticity membrane models based on 3D incompressible neo-Hookean and Mooney-Rivlin materials, respectively. In particular, (iii) and (iv) are superior models for elastomers. The 2D nonlinear, hyperelastic models (ii)-(iv) all incorporate the same quadratic bending energy used in FvK. Our results illuminate serious shortcomings of the latter in this problem, while also pointing to inaccuracies of model (ii) - in spite of yielding the correct qualitative phenomena in our earlier work. In each of these, the shortcoming is a due to a deficiency of the membrane part of the model.

  19. The High Stability Engine Control (HISTEC) Program: Flight Demonstration Phase

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    Future aircraft turbine engines, both commercial and military, must be able to accommodate expected increased levels of steady-state and dynamic engine-face distortion. The current approach of incorporating sufficient 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, integrated engine control system that uses measurement-based 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 has been developed and was successfully flight demonstrated on the F-15 ACTIVE aircraft during the summer of 1997. The flight demonstration was planned and carried out in two phases, the first to show distortion estimation, and the second to show distortion accommodation. Post-flight analysis shows that the HISTEC technologies are able to successfully estimate and accommodate distortion, transiently setting the stall margin requirement on-line and in real-time. This allows the design stall margin requirement to be reduced, which in turn can be traded for significantly increased performance and/or decreased weight. Flight demonstration of the HISTEC technologies has significantly reduced the risk of transitioning the technology to tactical and commercial engines.

  20. High energy density Z-pinch plasmas using flow stabilization

    SciTech Connect

    Shumlak, U. Golingo, R. P. Nelson, B. A. Bowers, C. A. Doty, S. A. Forbes, E. G. Hughes, M. C. Kim, B. Knecht, S. D. Lambert, K. K. Lowrie, W. Ross, M. P. Weed, J. R.

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  1. Structure and stability of hydrous minerals at high pressure

    NASA Technical Reports Server (NTRS)

    Duffy, T. S.; Fei, Y.; Meade, C.; Hemley, R. J.; Mao, H. K.

    1994-01-01

    The presence of even small amounts of hydrogen in the Earth's deep interior may have profound effects on mantle melting, rheology, and electrical conductivity. The recent discovery of a large class of high-pressure H-bearing silicates further underscores the potentially important role for hydrous minerals in the Earth's mantle. Hydrogen may also be a significant component of the Earth's core, as has been recently documented by studies of iron hydride at high pressure. In this study, we explore the role of H in crystal structures at high pressure through detailed Raman spectroscopic and x ray diffraction studies of hydrous minerals compressed in diamond anvil cells. Brucite, Mg(OH)2, has a simple structure and serves as an analogue for the more complex hydrous silicates. Over the past five years, this material has been studied at high pressure using shock-compression, powder x ray diffraction, infrared spectroscopy, Raman spectroscopy, and neutron diffraction. In addition, we have recently carried out single-crystal synchrotron x-ray diffraction on Mg(OH)2 and Raman spectroscopy on Mg(OD)2 at elevated pressure. From all these studies, an interesting picture of the crystal chemical behavior of this material at high pressure is beginning to emerge. Some of the primary conclusions are as follows: First, hydrogen bonding is enhanced by the application of pressure. Second, layered minerals which are elastically anisotropic at low pressure may not be so at high pressure. Furthermore, the brucite data place constraints on the effect of hydrogen on seismic velocities and density at very high pressure. Third, the stability of hydrous minerals may be enhanced at high P by subtle structural rearrangements that are difficult to detect using traditional probes and require detailed spectroscopic analyses. Finally, brucite appears to be unique in that it undergoes pressure-induced disordering that is confined solely to the H-containing layers of the structure.

  2. Structure and stability of hydrous minerals at high pressure

    NASA Astrophysics Data System (ADS)

    Duffy, T. S.; Fei, Y.; Meade, C.; Hemley, R. J.; Mao, H. K.

    The presence of even small amounts of hydrogen in the Earth's deep interior may have profound effects on mantle melting, rheology, and electrical conductivity. The recent discovery of a large class of high-pressure H-bearing silicates further underscores the potentially important role for hydrous minerals in the Earth's mantle. Hydrogen may also be a significant component of the Earth's core, as has been recently documented by studies of iron hydride at high pressure. In this study, we explore the role of H in crystal structures at high pressure through detailed Raman spectroscopic and x ray diffraction studies of hydrous minerals compressed in diamond anvil cells. Brucite, Mg(OH)2, has a simple structure and serves as an analogue for the more complex hydrous silicates. Over the past five years, this material has been studied at high pressure using shock-compression, powder x ray diffraction, infrared spectroscopy, Raman spectroscopy, and neutron diffraction. In addition, we have recently carried out single-crystal synchrotron x-ray diffraction on Mg(OH)2 and Raman spectroscopy on Mg(OD)2 at elevated pressure. From all these studies, an interesting picture of the crystal chemical behavior of this material at high pressure is beginning to emerge. Some of the primary conclusions are as follows: First, hydrogen bonding is enhanced by the application of pressure. Second, layered minerals which are elastically anisotropic at low pressure may not be so at high pressure. Furthermore, the brucite data place constraints on the effect of hydrogen on seismic velocities and density at very high pressure. Third, the stability of hydrous minerals may be enhanced at high P by subtle structural rearrangements that are difficult to detect using traditional probes and require detailed spectroscopic analyses. Finally, brucite appears to be unique in that it undergoes pressure-induced disordering that is confined solely to the H-containing layers of the structure.

  3. 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.

  4. Novel alpha-melanocyte stimulating hormone peptide analogues with high candidacidal activity.

    PubMed

    Grieco, Paolo; Rossi, Claudia; Colombo, Gualtiero; Gatti, Stefano; Novellino, Ettore; Lipton, James M; Catania, Anna

    2003-02-27

    alpha-Melanocyte stimulating hormone (alpha-MSH) is an endogenous linear tridecapeptide with potent antiinflammatory effects. We recently demonstrated that alpha-MSH and its C-terminal sequence Lys-Pro-Val (alpha-MSH (11-13)) have antimicrobial effects against two major and representative pathogens: Staphylococcus aureus and Candida albicans. In an attempt to improve the candidacidal activity of alpha-MSH and to better understand the peptide structure-antifungal activity relations, we designed and synthesized novel peptide analogues. Because previous data suggested that antimicrobial effects of alpha-MSH were receptor-mediated, we chose to focus on the sequence alpha-MSH (6-13), which contains the invariant core sequence His-Phe-Arg-Trp (6-9) that is important for binding to the known melanocortin receptors and also contains the sequence Lys-Pro-Val (11-13) that is known to be important for antimicrobial activity. In this structure-activity study, we discovered several compounds that have greater candidacidal activity than alpha-MSH. The peptide [d-Nal-7,Phe-12]-alpha-MSH (6-13) was the most potent of the analogues tested. The present results are very encouraging because they show the great potential of these peptides as a truly novel class of candidacidal compounds.

  5. A control system for maintaining high stability in gas pressure

    SciTech Connect

    Wuest, C.R.; Hendricks, C.D.

    1987-09-01

    A pressure control system has been implemented on an experiment designed to detect the presence of fractional charges in bulk matter. The experiment utilizes a liquid-droplet generation technique requiring high-stability gas-pressure delivery to ensure accurate data collection. The pressure control system consists of a pressurized mercury reservoir containing a low-vapor-pressure, diffusion-pump oil. A commercially available differential pressure transducer, servo-driven valve, and controller sense the pressure fluctuations with respect to a static reference pressure. The system can maintain constant pressure to better than one part in 10,000 at working pressures in the range of 100 to 300 psi. 3 refs., 7 figs.

  6. Developing Multilayer Thin Film Strain Sensors With High Thermal Stability

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Gonzalez, Jose M., III

    2006-01-01

    A multilayer thin film strain sensor for large temperature range use is under development using a reactively-sputtered process. The sensor is capable of being fabricated in fine line widths utilizing the sacrificial-layer lift-off process that is used for micro-fabricated noble-metal sensors. Tantalum nitride films were optimized using reactive sputtering with an unbalanced magnetron source. A first approximation model of multilayer resistance and temperature coefficient of resistance was used to set the film thicknesses in the multilayer film sensor. Two multifunctional sensors were fabricated using multilayered films of tantalum nitride and palladium chromium, and tested for low temperature resistivity, TCR and strain response. The low temperature coefficient of resistance of the films will result in improved stability in thin film sensors for low to high temperature use.

  7. A Colloidal Stability Assay Suitable for High-Throughput Screening.

    PubMed

    Abarca, Carla; Ali, M Monsur; Yang, Songtao; Dong, Xiaofei; Pelton, Robert H

    2016-03-01

    A library of 32 polystyrene copolymer latexes, with diameters ranging between 53 and 387 nm, was used to develop and demonstrate a high-throughput assay using a 96-well microplate platform to measure critical coagulation concentrations, a measure of colloidal stability. The most robust assay involved an automated centrifugation-decantation step to remove latex aggregates before absorbance measurements, eliminating aggregate interference with optical measurements made through the base of the multiwell plates. For smaller nanoparticles (diameter <150 nm), the centrifugation-decantation step was not required as the interference was less than with larger particles. Parallel measurements with a ChemiDoc MP plate scanner gave indications of aggregation; however, the results were less sensitive than the absorbance measurements.

  8. Energy stability in a high average power FEL

    SciTech Connect

    Mermings, L.; Bisognano, J.; Delayen, J.

    1995-12-31

    Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields or beam current are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents are determined. Furthermore, the analytical model is extended to include feedback. Comparison with simulation results derived from direct integration of the equations of motion is presented. Design strategies to increase the instability threshold are discussed and the UV Demo FEL, proposed for construction at CEBAF, and the INP Recuperatron at Novosibirsk are used as examples.

  9. Metallurgical, chemical, and stress corrosion cracking characterization of high oxygen alpha+beta titanium-15Molybdenum

    NASA Astrophysics Data System (ADS)

    Williamson, Randall Scott

    Titanium and its alloys are used as biomaterials due to their excellent corrosion resistance, mechanical properties, superior biocompatibility, metallurgical properties and fatigue characteristics. Titanium implants, like all biomaterials, can have failures in-vivo during their service life. The predominant mechanism observed for titanium implant/device failures is corrosion fatigue. However, other failure mechanisms can be observed. One such failure mechanism is stress corrosion cracking. Stress corrosion cracking and its presence or absence in in-vivo failures of titanium and titanium alloys has historically been debated. Several researchers have stated that titanium and titanium alloys can fail due to stress corrosion cracking under physiological conditions when the oxygen weight percent exceeds 0.20. The purpose of this research was to evaluate and to compare metallurgical, chemical, and stress corrosion cracking (SCC) properties of two heats of alpha+beta Ti-15Mo with oxygen weight concentrations of approximately 0.18% (Heat UC30) and 0.73% (Heat UC32B). The results were compared to previous findings for beta Ti-15Mo, Grade 4 CP Ti, Ti-6A1-4V ELI and another low oxygen weight percent alpha+beta Ti-15Mo. Metallurgical evaluations showed that Heat UC30 had an inhomogeneous distribution of alpha and beta phases while Heat UC32B exhibited a homogenous microstructure. Heat treatment processes (annealing and aging) were completed on both heats to homogenize and to optimize the microstructures. Smooth and notched tensile test results showed that both heats had equal or superior tensile properties compared to CPTi and other Ti alloys. Corrosion resistance testing showed a variance in Heat UC30 samples while little variance was shown in Heat UC32B samples. Chemical composition results found that both alloys were within specification and internal melt limits. Smooth and notched samples for both Heat UC30 and Heat UC32B showed no evidence of SCC failure mechanisms in

  10. Quantitative digital image analysis of chromogenic assays for high throughput screening of alpha-amylase mutant libraries.

    PubMed

    Shankar, Manoharan; Priyadharshini, Ramachandran; Gunasekaran, Paramasamy

    2009-08-01

    An image analysis-based method for high throughput screening of an alpha-amylase mutant library using chromogenic assays was developed. Assays were performed in microplates and high resolution images of the assay plates were read using the Virtual Microplate Reader (VMR) script to quantify the concentration of the chromogen. This method is fast and sensitive in quantifying 0.025-0.3 mg starch/ml as well as 0.05-0.75 mg glucose/ml. It was also an effective screening method for improved alpha-amylase activity with a coefficient of variance of 18%.

  11. The Lyman alpha forest of the high-z quasar 0000-263

    NASA Technical Reports Server (NTRS)

    Penprase, Bryan; Gilmozzi, Roberto; Bowen, David; Madau, Piero

    1993-01-01

    Medium-resolution (delta(v) = 45 km/s) optical spectra of the bright, high-redshift (z = 4.1) quasar 0000-263 taken at the ESO 3.5-m NTT telescope were analyzed to determine the distribution of column densities, velocities and line widths of the Lyman-alpha forest absorption components. The values of NH, b, and z were determined by fitting Voigt profiles to the lines, and convolving with a Gaussian instrumental response function. Over 350 components with log N(sub H) greater than 13.2 were identified. An analysis of the dependence of the number of components with z reveals that the number evolution of components obeys the power law dN/dz varies as (1+z)(sup gamma), where gamma = 0.5 +/- 0.4 for the sample of 182 lines with log N(sub H) greater than 14.0. The distribution of component strengths is found to obey f(N(sub H)) varies as N(sub h)(sup -beta), where beta = -1.55 for components with log(N(sub H)) is greater than 14.7, and beta = -0.68 for the components with log(N(sub H)) greater than 13.5. A distinct break in the f(N(sub H)) histogram is also observed, at log(N(sub H)) is approximately 14.7. The results are briefly considered in the context of theoretical models of quasar Lyman alpha clouds and their evolution.

  12. Irradiation of Mesenchymal Stromal Cells with Low and High Doses of Alpha Particles Induces Senescence and/or Apoptosis.

    PubMed

    Alessio, Nicola; Esposito, Giuseppe; Galano, Giovanni; De Rosa, Roberto; Anello, Pasquale; Peluso, Gianfranco; Tabocchini, Maria Antonella; Galderisi, Umberto

    2017-03-02

    The use of high-linear energy transfer charged particles is gaining attention as a medical tool because of the emission of radiations with an efficient cell-killing ability. Considerable interest has developed in the use of targeted alpha-particle therapy for the treatment of micrometastases. Moreover, the use of helium beams is gaining momentum, especially for treating pediatric tumors. We analyzed the effects of alpha particles on bone marrow mesenchymal stromal cells (MSCs), which have a subpopulation of stem cells capable of generating adipocytes, chondrocytes, and osteocytes. Further, these cells contribute toward maintenance of homeostasis in the body. MSCs were irradiated with low and high doses of alpha particles or X-rays and a comparative biological analysis was performed. At a low dose (40 mGy), alpha particles exhibited a limited negative effect on the biology of MSCs compared with X-rays. No significant perturbation of cell cycle was observed, and a minimal increase in apoptosis or senescence was detected. Self-renewal was preserved as revealed by the CFU assay. On the contrary, with 2000 mGy alpha particles we observed adverse effects on the vitality, functionality, and stemness of MSCs. These results are the consequence of different proportion of cells targeted by alpha particles or X-rays and the quality of induced DNA damage. The present study suggests that radiotherapy with alpha particles may spare healthy stem cells more efficaciously than X-ray treatments, an observation that should be taken into consideration by physicians while planning irradiation of tumor areas close to stem cell niches, such as bone marrow. This article is protected by copyright. All rights reserved.

  13. Investigation of high-alpha lateral-directional control power requirements for high-performance aircraft

    NASA Technical Reports Server (NTRS)

    Foster, John V.; Ross, Holly M.; Ashley, Patrick A.

    1993-01-01

    Designers of the next-generation fighter and attack airplanes are faced with the requirements of good high angle-of-attack maneuverability as well as efficient high speed cruise capability with low radar cross section (RCS) characteristics. As a result, they are challenged with the task of making critical design trades to achieve the desired levels of maneuverability and performance. This task has highlighted the need for comprehensive, flight-validated lateral-directional control power design guidelines for high angles of attack. A joint NASA/U.S. Navy study has been initiated to address this need and to investigate the complex flight dynamics characteristics and controls requirements for high angle-of-attack lateral-directional maneuvering. A multi-year research program is underway which includes groundbased piloted simulation and flight validation. This paper will give a status update of this program that will include a program overview, description of test methodology and preliminary results.

  14. Investigation of High-alpha Lateral-directional Control Power Requirements for High-performance Aircraft

    NASA Technical Reports Server (NTRS)

    Foster, John V.; Ross, Holly M.; Ashley, Patrick A.

    1993-01-01

    Designers of the next-generation fighter and attack airplanes are faced with the requirements of good high-angle-of-attack maneuverability as well as efficient high speed cruise capability with low radar cross section (RCS) characteristics. As a result, they are challenged with the task of making critical design trades to achieve the desired levels of maneuverability and performance. This task has highlighted the need for comprehensive, flight-validated lateral-directional control power design guidelines for high angles of attack. A joint NASA/U.S. Navy study has been initiated to address this need and to investigate the complex flight dynamics characteristics and controls requirements for high-angle-of-attack lateral-directional maneuvering. A multi-year research program is underway which includes ground-based piloted simulation and flight validation. This paper will give a status update of this program that will include a program overview, description of test methodology and preliminary results.

  15. High mobility and high stability glassy metal-oxynitride materials and devices

    PubMed Central

    Lee, Eunha; Kim, Taeho; Benayad, Anass; Hur, Jihyun; Park, Gyeong-Su; Jeon, Sanghun

    2016-01-01

    In thin film technology, future semiconductor and display products with high performance, high density, large area, and ultra high definition with three-dimensional functionalities require high performance thin film transistors (TFTs) with high stability. Zinc oxynitride, a composite of zinc oxide and zinc nitride, has been conceded as a strong substitute to conventional semiconductor film such as silicon and indium gallium zinc oxide due to high mobility value. However, zinc oxynitride has been suffered from poor reproducibility due to relatively low binding energy of nitrogen with zinc, resulting in the instability of composition and its device performance. Here we performed post argon plasma process on zinc oxynitride film, forming nano-crystalline structure in stable amorphous matrix which hampers the reaction of oxygen with zinc. Therefore, material properties and device performance of zinc oxynitride are greatly enhanced, exhibiting robust compositional stability even exposure to air, uniform phase, high electron mobility, negligible fast transient charging and low noise characteristics. Furthermore, We expect high mobility and high stability zinc oxynitride customized by plasma process to be applicable to a broad range of semiconductor and display devices. PMID:27044371

  16. High mobility and high stability glassy metal-oxynitride materials and devices

    NASA Astrophysics Data System (ADS)

    Lee, Eunha; Kim, Taeho; Benayad, Anass; Hur, Jihyun; Park, Gyeong-Su; Jeon, Sanghun

    2016-04-01

    In thin film technology, future semiconductor and display products with high performance, high density, large area, and ultra high definition with three-dimensional functionalities require high performance thin film transistors (TFTs) with high stability. Zinc oxynitride, a composite of zinc oxide and zinc nitride, has been conceded as a strong substitute to conventional semiconductor film such as silicon and indium gallium zinc oxide due to high mobility value. However, zinc oxynitride has been suffered from poor reproducibility due to relatively low binding energy of nitrogen with zinc, resulting in the instability of composition and its device performance. Here we performed post argon plasma process on zinc oxynitride film, forming nano-crystalline structure in stable amorphous matrix which hampers the reaction of oxygen with zinc. Therefore, material properties and device performance of zinc oxynitride are greatly enhanced, exhibiting robust compositional stability even exposure to air, uniform phase, high electron mobility, negligible fast transient charging and low noise characteristics. Furthermore, We expect high mobility and high stability zinc oxynitride customized by plasma process to be applicable to a broad range of semiconductor and display devices.

  17. Expectancy of pain is influenced by motor preparation: a high-resolution EEG study of cortical alpha rhythms.

    PubMed

    Babiloni, Claudio; Brancucci, Alfredo; Capotosto, Paolo; Arendt-Nielsen, Lars; Chen, Andrew C N; Rossini, Paolo Maria

    2005-04-01

    This high-resolution electroencephalographic (EEG) study on alpha event-related desynchronization (ERD) evaluated whether anticipatory activity precedes a sensorimotor interaction induced by concomitant painful stimuli and sensorimotor demand. An omitted-stimulus paradigm induced the expectancy of the painful stimulation at the left hand. In the experimental condition, the painful stimulation was associated with a visual go/no-go task triggering right-hand movements. Two control conditions manipulated the painful sensorimotor interaction variable. Compared with the control conditions, the expectancy of the painful sensorimotor interaction increased the high-band alpha EEG oscillations over the right primary sensorimotor cortex contralateral to the nociceptive stimuli and, to a lesser extent, over the centroparietal midline. These findings suggest that concomitant painful stimuli and simple sensorimotor go/no-go demands affect anticipatory activity as revealed by alpha ERD.

  18. [Characteristics of cortical activity in persons with high and low verbal creativity: analysis of alpha1,2 rhythms].

    PubMed

    Razumnikova, O M; Tarasova, I V; Vol'f, N V

    2009-01-01

    Creativity-related changes in alpha power in low-frequency (8-10 Hz) and high-frequency (10-13 Hz) bands were studied in university students having regard to generation of original ideas during performance of two verbal tasks. A high-creative group enrolled 16 subjects asked to generate original words--associates to the triads of verbal stimuli and 14 subjects who were asked to compose a sentence using triads of nouns from remote semantic categories. Low-creative groups included 22 and 13 individuals, respectively. In low-frequency band, highly creative subjects showed a higher level of alpha power than low creative individuals. In the high-frequency band, task-related alpha2 power desynchronization was different in these groups: high-creative individuals had higher power score than low-creative mostly in the anterior and parietal cortical areas. These data and a factor structure of alpha rhythm indices may be evidence of different strategies of information selection in highly and low creative persons.

  19. High-pressure infrared sepctra of alpha-quartz, coesite, stishovite and silica glass

    NASA Technical Reports Server (NTRS)

    Williams, Q.; Hemley, R. J.; Kruger, M. B.; Jeanloz, R.

    1993-01-01

    High-pressure infrared absorption spectra of alpha-quatz, coesite, stishovite, and SiO2 glass are consistent with the primary compression mechanism of the initially tetrahedrally bonded phases being the bending of the Si-O-Si angle at pressures less than 10-20 GPa. At higher pressures, up to 40 GPa, we observe a decline in the intensity of the infrared SiO4 asymmetric-stretching vibrations of all three phases, with an increase in the relative amplitude between 700 and 900/cm. This change in intensities is attributed to an increase in the average coordination number of silicon through extreme distortion of tetrahedra. At pressures above approximately 20 GPa, the low-pressure crystalline polymorphs gradually become amorphous, and the infrared spectra provide evidence for an increase in silicon coordination in these high-density amorphous phases. The pressure-amorphized samples prepared from quartz and coesite differ structurally both from each other and from silica glass that has been compressed, and the high pressure spectra indicate that these materials are considerably more disordered than stishovite under comparable pressure conditions. Average mode Grueneisen parameters calculated for quartz, stishovite and fused silica from both infrared and Raman spectra are compatible with the corresponding thermodynamic value of the Grueneisen parameter, however, that of coesite is significantly discrepant.

  20. High-Throughput Screening Methodology to Identify Alpha-Synuclein Aggregation Inhibitors.

    PubMed

    Pujols, Jordi; Peña-Díaz, Samuel; Conde-Giménez, María; Pinheiro, Francisca; Navarro, Susanna; Sancho, Javier; Ventura, Salvador

    2017-03-02

    An increasing number of neurodegenerative diseases are being found to be associated with the abnormal accumulation of aggregated proteins in the brain. In Parkinson's disease, this process involves the aggregation of alpha-synuclein (α-syn) into intraneuronal inclusions. Thus, compounds that inhibit α-syn aggregation represent a promising therapeutic strategy as disease-modifying agents for neurodegeneration. The formation of α-syn amyloid aggregates can be reproduced in vitro by incubation of the recombinant protein. However, the in vitro aggregation of α-syn is exceedingly slow and highly irreproducible, therefore precluding fast high throughput anti-aggregation drug screening. Here, we present a simple and easy-to-implement in-plate method for screening large chemical libraries in the search for α-syn aggregation modulators. It allows us to monitor aggregation kinetics with high reproducibility, while being faster and requiring lower protein amounts than conventional aggregation assays. We illustrate how the approach enables the identification of strong aggregation inhibitors in a library of more than 14,000 compounds.

  1. Strain fields around high-energy ion tracks in {alpha}-quartz

    SciTech Connect

    Follstaedt, D. M.; Norman, A. K.; Doyle, B. L.; McDaniel, F. D.

    2006-09-15

    Transmission electron microscopy has been used to image the tracks of high-energy {sup 197}Au{sup +26} (374 MeV) and {sup 127}I{sup +18} (241 MeV) ions incident in a nonchanneling direction through a prethinned specimen of hexagonal {alpha}-quartz (SiO{sub 2}). These ions have high electronic stopping powers in quartz, 24 and 19 keV/nm, respectively, which are sufficient to produce a disordered latent track. When the tracks are imaged with diffraction contrast using several different reciprocal lattice vectors, they exhibit a radial strain extending outward from their disordered centerline approximately 16 nm into the crystalline surroundings. The images are consistent with a radial strain field with cylindrical symmetry around the amorphous track, like that found in models developed to account for the lateral expansion of amorphous SiO{sub 2} films produced by irradiation with high-energy ions. These findings provide an experimental basis for increased confidence in such modeling.

  2. High-Throughput Screening Methodology to Identify Alpha-Synuclein Aggregation Inhibitors

    PubMed Central

    Pujols, Jordi; Peña-Díaz, Samuel; Conde-Giménez, María; Pinheiro, Francisca; Navarro, Susanna; Sancho, Javier; Ventura, Salvador

    2017-01-01

    An increasing number of neurodegenerative diseases are being found to be associated with the abnormal accumulation of aggregated proteins in the brain. In Parkinson’s disease, this process involves the aggregation of alpha-synuclein (α-syn) into intraneuronal inclusions. Thus, compounds that inhibit α-syn aggregation represent a promising therapeutic strategy as disease-modifying agents for neurodegeneration. The formation of α-syn amyloid aggregates can be reproduced in vitro by incubation of the recombinant protein. However, the in vitro aggregation of α-syn is exceedingly slow and highly irreproducible, therefore precluding fast high throughput anti-aggregation drug screening. Here, we present a simple and easy-to-implement in-plate method for screening large chemical libraries in the search for α-syn aggregation modulators. It allows us to monitor aggregation kinetics with high reproducibility, while being faster and requiring lower protein amounts than conventional aggregation assays. We illustrate how the approach enables the identification of strong aggregation inhibitors in a library of more than 14,000 compounds. PMID:28257086

  3. High solid and high stability waterborne polyurethanes via ionic groups in soft segments and chain termini.

    PubMed

    Lee, S K; Kim, B K

    2009-08-01

    High solid and high stability waterborne polyurethanes were molecularly designed and synthesized. The positions and concentrations of the anionic groups were varied, along with the molecular weights of the polyol. It was found that the dispersions containing ionic groups at the chain termini (called terminal ions) gave the smallest dispersion size, and the highest dispersion stability and viscosity, whereas the hard ions, containing ionic groups in the hard segments, resulted in the greatest swelling in water. However, the mechanical and dynamic mechanical properties of the dispersion cast films were similar. It was demonstrated that highly stable dispersions with a high solid content (45%) can be obtained at a low ionic content (2%) by simply incorporating the ionic groups at the flexible chain ends. The results were interpreted in terms of the high mobility and low free energy of the chain ends.

  4. A Silica Long Base Tiltmeter with high Stability and Resolution

    NASA Astrophysics Data System (ADS)

    Boudin, F.; Bernard, P.; Longuevergne, L.; Florsch, N.; Bour, O.; Esnoult, M.; Courteille, C.; Caudal, J.

    2006-12-01

    Two 100 m long silica water tube tiltmeters (based on the communicating vessels' principle) were installed in the French Vosges Massif one along the 37°E direction and the other one along the 127°E direction. This experiment was part of a hydrology research project which started at the end of the year 2004 to study the effect of the hydrological load of an aquifer in the Rhin Valley and the associated crustal flexure. In order to gather relevant data, we need to be able to measure the strain or tilt with high resolution and stability for periods ranging from few minutes to few years. The site is a mine located at 35 km eastward from the large Rhin aquifer. Our instruments have shown a remarkably good stability and resolution (6.5x10-9rad/month) and were even able to detect the toroidal and spheroidal free oscillations of the Earth excited by the two last major earthquakes of Sumatra. Long base Tiltmeters will be a part of future multi-parameters survey projects if they can be installed in a larger variety of sites. After this first hydrological experiment we set up a new pair of long base tiltmeters to observe the influence of a underground aquifer exploited by the town of Ploemeur (Morbihan). Water pumping has been stopped during 41 hours to prompt a variation of volume between 2000 and 4000 m3 inducing a variation of pressure in the cavity. In this multi-parameters survey which included GPS, absolute and relative gravimetric and tiltmetric measurements only the long base tiltmeters have a sufficient resolution to detect the vertical rock deformation of 0.1 to 1 mm over a base of 1000m.

  5. Total alpha-globin gene cluster deletion has high frequency in Filipinos

    SciTech Connect

    Hunt, J.A.; Haruyama, A.Z.; Chu, B.M.

    1994-09-01

    Most {alpha}-thalassemias [Thal] are due to large deletions. In Southeast Asians, the (--{sup SEA}) double {alpha}-globin gene deletion is common, 3 (--{sup Tot}) total {alpha}-globin cluster deletions are known: Filipino (--{sup Fil}), Thai (--{sup Thai}), and Chinese (--{sup Chin}). In a Hawaii Thal project, provisional diagnosis of {alpha}-Thal-1 heterozygotes was based on microcytosis, normal isoelectric focusing, and no iron deficiency. One in 10 unselected Filipinos was an {alpha}-Thal-1 heterozygote, 2/3 of these had a (--{sup Tot}) deletion: a {var_sigma}-cDNA probe consistently showed fainter intensity of the constant 5.5 kb {var_sigma}{sub 2} BamHI band, with no heterzygosity for {var_sigma}-globin region polymorphisms; {alpha}-cDNA or {var_sigma}-cDNA probes showed no BamHI or BglII bands diagnostic of the (--{sup SEA}) deletion; bands for the (-{alpha}) {alpha}-Thal-2 single {alpha}-globin deletions were only seen in Hb H cases. A reliable monoclonal anti-{var_sigma}-peptide antibody test for the (--{sup SEA}) deletion was always negative in (--{sup Tot}) samples. Southern digests with the Lo probe, a gift from D. Higgs of Oxford Univ., confirmed that 49 of 50 (--{sup Tot}) chromosomes in Filipinos were (--{sup Fil}). Of 20 {alpha}-Thal-1 hydrops born to Filipinos, 11 were (--{sup Fil}/--{sup SEA}) compound heterozygotes; 9 were (--{sup SEA}/--{sup SEA}) homozygotes, but none was a (--{sup Fil}/--{sup Fil}).

  6. Correlation between chemical structure, receptor binding, and biological activity of some novel, highly active, 16 alpha, 17 alpha-acetal-substituted glucocorticoids.

    PubMed

    Dahlberg, E; Thalén, A; Brattsand, R; Gustafsson, J A; Johansson, U; Roempke, K; Saartok, T

    1984-01-01

    The affinity for the glucocorticoid receptor in rat skeletal muscle of some glucocorticoids with a new type of 16 alpha, 17 alpha-acetal substituent has been estimated and correlated to the glucocorticoid activities in three in vivo systems in rats. Budesonide (an approximately 1:1 mixture of the C(22) epimers of 11 beta, 21-dihydroxy-16 alpha, 17 alpha-[(22R,S)-propylmethylenedioxy]-pregna-1,4-diene-3,20-dione) and the isolated (22R)- and (22S)-epimers bound to the same binding site as the potent glucocorticoids dexamethasone (DEX) or triamcinolone 16 alpha, 17 alpha-acetonide (TA), but with even higher affinity than DEX or TA, despite the lack of a 9 alpha-fluoro atom in budesonide and its epimers. The (22R)-epimer was twice as active as the (22S)-epimer, 4 times more active than TA, and 14 times more active than DEX. The introduction of a 9 alpha-fluoro atom slightly decreased the binding affinity of the (22R)-epimer of budesonide, in contrast to the positive effect of 9 alpha-fluorination of, e.g., 16 alpha, 17 alpha-acetonides. The negative influence of 9 alpha-fluorination of the (22R)-epimer was partially reversed in the 6 alpha, 9 alpha-difluorinated (22R)-epimer. Nevertheless, the fluorinated compounds were more active than DEX and TA (8 and 11 times more active than DEX, and 2 and 3 times more active than TA, in case of the 9 alpha-fluoro- and 6 alpha, 9 alpha-difluoro-derivatives of the (22R)-epimer, respectively). Budesonide is metabolized mainly to 16 alpha-hydroxyprednisolone (11 beta, 16 alpha, 17 alpha, 21-tetrahydroxy-pregna-1,4-diene-3,20-dione) and 6 beta-hydroxy-budesonide. Both metabolites were very weak competitors for the ligand-binding sites on the receptor (3% and 6% of the affinity of DEX, respectively). The affinity for the receptor in vitro was closely correlated to the topical glucocorticoid activity in vivo for the 12 steroids compared (r = 0.98; R = 0.98), which supports the contention that in vitro tests for receptor affinity are

  7. Carbocation Stability in H-ZSM5 at High Temperature

    SciTech Connect

    Ferguson, Glen A.; Cheng, Lei; Bu, Lintao; Kim, Seonah; Robichaud, David J.; Nimlos, Mark R.; Curtiss, Larry A.; Beckham, Gregg T.

    2015-10-26

    Zeolites are common catalysts for multiple industrial applications, including alcohol dehydration to produce olefins, and given their commercial importance, reaction mechanisms in zeolites have long been proposed and studied. Some proposed reaction mechanisms for alcohol dehydration exhibit noncyclic carbocation intermediates or transition states that resemble carbocations, and several previous studies suggest that the tert-butyl cation is the only noncyclic cation more stable than the corresponding chemisorbed species with the hydrocarbon bound to the framework oxygen (i.e., an alkoxide). To determine if carbocations can exist at high temperatures in zeolites, where these catalysts are finding new applications for biomass vapor-phase upgrading (~500 °C), the stability of carbocations and the corresponding alkoxides were calculated with two ONIOM embedding methods (M06-2X/6-311G(d,p):M06-2X/3-21G) and (PBE-D3/6-311G(d,p):PBE-D3/3-21G) and plane-wave density functional theory (DFT) using the PBE functional corrected with entropic and Tkatchenko–Scheffler van der Waals corrections. Additionally, the embedding methods tested are unreliable at finding minima for primary carbocations, and only secondary or higher carbocations can be described with embedding methods consistent with the periodic DFT results. The relative energy between the carbocations and alkoxides differs significantly between the embedding and the periodic DFT methods. The difference is between ~0.23 and 14.30 kcal/mol depending on the molecule, the model, and the functional chosen for the embedding method. At high temperatures, the pw-DFT calculations predict that the allyl, isopropyl, and sec-butyl cations exhibit negligible populations while acetyl and tert-butyl cations exhibit significant populations (>10%). Furthermore, the periodic DFT results indicate that mechanisms including secondary and tertiary carbocations intermediates or carbocations stabilized by adjacent oxygen or double bonds are

  8. A parametric study of planform and aeroelastic effects on aerodynamic center, alpha- and q- stability derivatives. Appendix A: A computer program for calculating alpha- and q- stability derivatives and induced drag for thin elastic aeroplanes at subsonic and supersonic speeds

    NASA Technical Reports Server (NTRS)

    Roskam, J.; Lan, C.; Mehrotra, S.

    1972-01-01

    The computer program used to determine the rigid and elastic stability derivatives presented in the summary report is listed in this appendix along with instructions for its use, sample input data and answers. This program represents the airplane at subsonic and supersonic speeds as (a) thin surface(s) (without dihedral) composed of discrete panels of constant pressure according to the method of Woodward for the aerodynamic effects and slender beam(s) for the structural effects. Given a set of input data, the computer program calculates an aerodynamic influence coefficient matrix and a structural influence coefficient matrix.

  9. The parameter stability of a high dk rigid lens material.

    PubMed

    Woods, C; Efron, N

    1999-01-01

    The use of rigid materials with high oxygen permeability (Dk) is on the increase, their major benefit being the reduction of hypoxia. However, there is a reluctance to use these materials possibly due to increased surface scratching, reduced wettability, increased deposition, reduced life expectancy and parameter instability. Considering parameter stability, various studies have demonstrated contradictory results or used high Dk materials based on the silicone acrylate polymer. This study was designed to investigate whether the parameters of a high Dk rigid fluorocarbon contact lens material changed during daily wear and extended wear schedules. Thirty five subjects, divided into group groups, Group I wore the lens on a daily wear basis, whereas those in Group II wore the lens on a monthly extended wear basis. The parameters and integrity of the lenses were monitored in both groups every 3 months. For lens integrity a statistically significant increase in surface scratching was demonstrated for the lenses worn by the subjects of both groups over the time of the study (Group I, F=7.990, P <0.0001 [ANCOVA]; Group II, F=6.241, P=0.003 [ANCOVA]). The only parameter to show a statistically significant variation over the study period was that of centre thickness for the lenses worn by the subjects in Group I (F=3.976, P=0.0063 [ANCOVA]), with a mean reduction in centre thickness of 0.022 mm at the 12 month visit. No change was noted for either group or between groups for the other parameters measured. This study demonstrates that the parameters of rigid contact lenses manufactured from high Dk fluorocarbons are stable with only a non-clinically significant reduction in centre thickness for the contact lenses worn by the subjects in Group I.

  10. Stable expression and characterisation of a human alpha 7 nicotinic subunit chimera: a tool for functional high-throughput screening.

    PubMed

    Craig, Peter J; Bose, Suchira; Zwart, Ruud; Beattie, Ruth E; Folly, Elizabeth A; Johnson, Laura R; Bell, Emma; Evans, Non M; Benedetti, Giovanni; Pearson, Kathy H; McPhie, Gordon I; Volsen, Stephen G; Millar, Neil S; Sher, Emanuele; Broad, Lisa M

    2004-10-11

    A chimera comprising the N-terminal region of the human alpha7 nicotinic acetylcholine receptor, fused to the transmembrane/C-terminal domains of the mouse serotonin 5-HT3 receptor, was constructed. Injection of the chimera cDNA into Xenopus oocytes, or transient transfection in human embryonic kidney (HEK-293) cells, resulted in the expression of functional channels that were sensitive to nicotinic acetylcholine, but not serotonin receptor ligands. In both systems, the responses obtained from chimeric receptors inactivated more slowly than those recorded following activation of wild-type alpha7 receptors. A stable HEK-293 cell line expressing the human alpha7/mouse 5-HT3 chimera was established, which showed that the chimera displayed a similar pharmacological profile to wild-type alpha7 receptors. Use of this chimera in high-throughput screening may enable the identification of novel pharmacological agents that will help to define further the role of alpha7 nicotinic receptors in physiology and disease.

  11. Maltose effects on barley malt diastatic power enzyme activity and thermostability at high isothermal mashing temperature: II. Alpha-amylase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maltose, the primary product of starch degradation during mashing, has the potential as a compatible solute to affect the activity of and increase the thermostability of barley malt alpha-amylase activity at high temperatures used in mashing and temperatures above those normally used in mashing. To ...

  12. Effect of alpha particles on Toroidal Alfven Eigenmodes

    SciTech Connect

    Berk, H.L.

    1992-11-01

    An overview is given of the analytic structure for the linear theory of the Toroidal Alfven Eigenmode (TAE), where multiple gap structures occur. A discussion is given of the alpha particle drive and the various dissipation mechanisms that can stabilize the system. A self-consistent calculation of the TAE mode, for a low-beta high-aspect-ratio plasma, indicates that though the alpha particle drive is comparable to the dissipation mechanisms, overall stability is still achieved for ignited ITER-like plasma. A brief discussion is given of the nonlinear theory for the TAE mode and how nonlinear alpha particle dynamics can be treated by mapping methods.

  13. Numerical investigation on the stabilization of the deceleration phase Rayleigh-Taylor instability due to alpha particle heating in ignition target

    NASA Astrophysics Data System (ADS)

    Fan, Zhengfeng; Zhu, Shaoping; Pei, Wenbing; Ye, Wenhua; Li, Meng; Xu, Xiaowen; Wu, Junfeng; Dai, Zhensheng; Wang, Lifeng

    2012-09-01

    Tritium-hydrogen-deuterium (THD) target is adopted in order to experimentally diagnose the properties of the ignition hot spot and the highly compressed main fusion fuel (Edwards M. J. et al., Phys. Plasmas, 18 (2011) 051003). As compared with deuterium-tritium (DT) target, the thermonuclear alpha particles which are needed to heat the fusion fuel, are much less in the THD target. In the present paper, the effect of alpha particle heating on the deceleration phase Rayleigh-Taylor instability (dp-RTI), which is one of the key problems in hot spot formation, is investigated systematically through numerical simulations. It is found that the mass ablation at the hot spot boundary is greatly increased due to the direct alpha particle heating. As a result, the dp-RTI growth rates are greatly reduced and the cut-off mode number decreases greatly from about 33 to 17. This explains why the hydrodynamic instability in the THD target grows more severely than in the DT ignition target.

  14. Development and validation of a high performance liquid chromatography assay for 17alpha-methyltestosterone in fish feed.

    PubMed

    Marwah, Ashok; Marwah, Padma; Lardy, Henry

    2005-09-25

    17alpha-Methyltestosterone (MT) is used to manipulate the gender of a variety of fish species. A high performance liquid chromatography (HPLC) internal standard method for the determination of 17alpha-methyltestosterone in fish feed using 3beta-methoxy-17beta-hydroxyandrost-5-en-7-one as internal standard (IS) has been developed. The method has been validated for the quantitation of MT in fish feed using 245 nm UV absorbance as the parent wavelength and 255 nm as a qualifier wavelength. The method was validated in the concentration range of 15.0-120 mg/kg of 17alpha-methyltestosterone in fish feed. Method was also found to be suitable for other feeds.

  15. Tip-alpha (hp0596 gene product) is a highly immunogenic Helicobacter pylori protein involved in colonization of mouse gastric mucosa.

    PubMed

    Godlewska, Renata; Pawlowski, Marcin; Dzwonek, Artur; Mikula, Michal; Ostrowski, Jerzy; Drela, Nadzieja; Jagusztyn-Krynicka, Elzbieta K

    2008-03-01

    A product of the Helicobacter pylori hp0596 gene (Tip-alpha) is a highly immunogenic homodimeric protein, unique for this bacterium. Cell fractionation experiments indicate that Tip-alpha is anchored to the inner membrane. In contrast, the three-dimensional model of the protein suggests that Tip-alpha is soluble or, at least, largely exposed to the solvent. hp0596 gene knockout resulted in a significant decrease in the level of H. pylori colonization as measured by real-time PCR assay. In addition, the Tip-alpha recombinant protein was determined to stimulate macrophage to produce IL-1alpha and TNF-alpha. Both results imply that Tip-alpha is rather loosely connected to the inner membrane and potentially released during infection.

  16. Differential sub-nuclear distribution of hypoxia-inducible factors (HIF)-1 and -2 alpha impacts on their stability and mobility

    PubMed Central

    Taylor, S. E.; Bagnall, J.; Mason, D.

    2016-01-01

    Cellular adaptation to hypoxia occurs via a complex programme of gene expression mediated by the hypoxia-inducible factor (HIF). The oxygen labile alpha subunits, HIF-1α/-2α, form a heterodimeric transcription factor with HIF-1β and modulate gene expression. HIF-1α and HIF-2α possess similar domain structure and bind to the same consensus sequence. However, they have different oxygen-dependent stability and activate distinct genes. To better understand these differences, we used fluorescent microscopy to determine precise localization and dynamics. We observed a homogeneous distribution of HIF-1α in the nucleus, while HIF-2α localized into speckles. We demonstrated that the number, size and mobility of HIF-2α speckles were independent of cellular oxygenation and that HIF-2α molecules were capable of exchanging between the speckles and nucleoplasm in an oxygen-independent manner. The concentration of HIF-2α into speckles may explain its increased stability compared with HIF-1α and its slower mobility may offer a mechanism for gene specificity. PMID:27655733

  17. Reconstitution of high affinity. cap alpha. /sub 2/ adrenergic agonist binding by fusion with a pertussis toxin substrate

    SciTech Connect

    Kim, M.H.; Neubig, R.R.

    1986-03-05

    High affinity ..cap alpha../sub 2/ adrenergic agonist binding is thought to occur via a coupling of the ..cap alpha../sub 2/ receptor with N/sub i/, the inhibitory guanyl nucleotide binding protein. Human platelet membranes pretreated at pH 11.5 exhibit a selective inactivation of agonist binding and N/sub i/. To further study the mechanism of agonist binding, alkali treated membranes (ATM) were mixed with membranes pretreated with 10 ..mu..M phenoxybenzamine to block ..cap alpha../sub 2/ receptors (POB-M). The combined membrane pellet was incubated in 50% polyethylene glycol (PEG) to promote membrane-membrane fusion and assayed for binding to the ..cap alpha../sub 2/ agonist (/sup 3/H)UK 14,304 (UK) and the antagonist (/sup 3/H) yohimbine. PEG treatment resulted in a 2-4 fold enhancement of UK binding whereas yohimbine binding was unchanged. No enhancement of UK binding was observed in the absence of PEG treatment. The reconstitution was dependent on the addition of POB-M. They found that a 1:1 ratio of POB-M:ATM was optimal. Reconstituted binding was inhibited by GppNHp. Fusion of rat C6 glioma cell membranes, which do not contain ..cap alpha../sub 2/ receptors, also enhanced agonist binding to ATM. Fusion of C6 membranes from cells treated with pertussis toxin did not enhance (/sup 3/H) UK binding. These data show that a pertussis toxin sensitive membrane component, possibly N/sub i/, can reconstitute high affinity ..cap alpha../sub 2/ agonist binding.

  18. Organic transistors with high thermal stability for medical applications

    NASA Astrophysics Data System (ADS)

    Kuribara, Kazunori; Wang, He; Uchiyama, Naoya; Fukuda, Kenjiro; Yokota, Tomoyuki; Zschieschang, Ute; Jaye, Cherno; Fischer, Daniel; Klauk, Hagen; Yamamoto, Tatsuya; Takimiya, Kazuo; Ikeda, Masaaki; Kuwabara, Hirokazu; Sekitani, Tsuyoshi; Loo, Yueh-Lin; Someya, Takao

    2012-03-01

    The excellent mechanical flexibility of organic electronic devices is expected to open up a range of new application opportunities in electronics, such as flexible displays, robotic sensors, and biological and medical electronic applications. However, one of the major remaining issues for organic devices is their instability, especially their thermal instability, because low melting temperatures and large thermal expansion coefficients of organic materials cause thermal degradation. Here we demonstrate the fabrication of flexible thin-film transistors with excellent thermal stability and their viability for biomedical sterilization processes. The organic thin-film transistors comprise a high-mobility organic semiconductor, dinaphtho[2,3-b:2‧,3‧-f]thieno[3,2-b]thiophene, and thin gate dielectrics comprising a 2-nm-thick self-assembled monolayer and a 4-nm-thick aluminium oxide layer. The transistors exhibit a mobility of 1.2 cm2 V-1s-1 within a 2 V operation and are stable even after exposure to conditions typically used for medical sterilization.

  19. The Phase Competition and Stability of High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Liu, W. H.; Wu, Y.; He, J. Y.; Zhang, Y.; Liu, C. T.; Lu, Z. P.

    2014-10-01

    Phase competition and stability of several typical high-entropy alloys (HEAs) were studied, and the effects of alloying additions and processing conditions on phase formation in these alloys were discussed. Alloying with chemically incompatible elements having a large difference in either the atomic size or enthalpy of mixing with constituting components in HEAs, e.g., Cu and Al in the FeCoNiCr alloy system, inevitably induced phase separation and stimulated formation of duplex solid-solution phases and even intermetallic compounds. The solid-solution phase in the as-cast FeCoNiCrMn HEA is extremely stable due to the good chemical compatibility among constituent components, but in the FeCoNiCrAl and (FeCoNiCrAl)99Si1 HEAs with the incompatible elements Al and Si, pretreatment and annealing processes could induce phase transitions and the formation of new phases, indicating that the as-cast solid-solution phases were destabilized by quenched-in chemical segregation, resulting from additions of the dissimilar elements.

  20. An Overview of the NASA F-18 High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Bowers, Albion H.; Pahle, Joseph W.; Wilson, R. Joseph; Flick, Bradley C.; Rood, Richard L.

    1996-01-01

    This paper gives an overview of the NASA F-18 High Alpha Research Vehicle. The three flight phases of the program are introduced, along with the specific goals and data examples taken during each phase. The aircraft configuration and systems needed to perform the disciplinary and inter-disciplinary research are discussed. The specific disciplines involved with the flight research are introduced, including aerodynamics, controls, propulsion, systems, and structures. Decisions that were made early in the planning of the aircraft project and the results of those decisions are briefly discussed. Each of the three flight phases corresponds to a particular aircraft configuration, and the research dictated the configuration to be flown. The first phase gathered data with the baseline F-18 configuration. The second phase was the thrust-vectoring phase. The third phase used a modified forebody with deployable nose strakes. Aircraft systems supporting these flights included extensive instrumentation systems, integrated research flight controls using flight control hardware and corresponding software, analog interface boxes to control forebody strakes, a thrust-vectoring system using external post-exit vanes around axisymmetric nozzles, a forebody vortex control system with strakes, and backup systems using battery-powered emergency systems and a spin recovery parachute.

  1. Thrust Vectoring on the NASA F-18 High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Bowers, Albion H.; Pahle, Joseph W.

    1996-01-01

    Investigations into a multiaxis thrust-vectoring system have been conducted on an F-18 configuration. These investigations include ground-based scale-model tests, ground-based full-scale testing, and flight testing. This thrust-vectoring system has been tested on the NASA F-18 High Alpha Research Vehicle (HARV). The system provides thrust vectoring in pitch and yaw axes. Ground-based subscale test data have been gathered as background to the flight phase of the program. Tests investigated aerodynamic interaction and vane control effectiveness. The ground-based full-scale data were gathered from static engine runs with image analysis to determine relative thrust-vectoring effectiveness. Flight tests have been conducted at the NASA Dryden Flight Research Center. Parameter identification input techniques have been developed. Individual vanes were not directly controlled because of a mixer-predictor function built into the flight control laws. Combined effects of the vanes have been measured in flight and compared to combined effects of the vanes as predicted by the cold-jet test data. Very good agreement has been found in the linearized effectiveness derivatives.

  2. Forebody Aerodynamics of the F-18 High Alpha Research Vehicle with Actuated Forebody Strakes

    NASA Technical Reports Server (NTRS)

    Fisher, David F.; Murri, Daniel G.

    2003-01-01

    Extensive pressure measurements and off-surface flow visualization were obtained on the forebody and strakes of the NASA F-18 High Alpha Research Vehicle (HARV) equipped with actuated forebody strakes. Forebody yawing moments were obtained by integrating the circumferential pressures on the forebody and strakes. Results show that large yawing moments can be generated with forebody strakes. At a 50 -angle-of-attack, deflecting one strake at a time resulted in a forebody yawing moment control reversal for small strake deflection angles. However, deflecting the strakes differentially about a 20 symmetric strake deployment eliminated the control reversal and produced a near linear variation of forebody yawing moment with differential strake deflection. At an angle of attack of 50 and for 0 and 20 symmetric strake deployments, a larger forebody yawing moment was generated by the forward fuselage (between the radome and the apex of the leading-edge extensions) than on the radome where the actuated forebody strakes were located. Cutouts on the flight vehicle strakes that were not on the wind tunnel models are believed to be responsible for deficits in the suction peaks on the flight radome pressure distributions and differences in the forebody yawing moments.

  3. Summary of in-flight flow visualization obtained from the NASA high alpha research vehicle

    NASA Technical Reports Server (NTRS)

    Fisher, David F.; Delfrate, John H.; Zuniga, Fanny A.

    1991-01-01

    A summary of the surface and off-surface flow visualization results obtained in flight on the F-18 high alpha research vehicle (HARV) is presented, highlighting the extensive 3-D vortical flow on the aircraft at angles of attack up to 50 degs. The emitted fluid technique, as well as tufts and flow cones, were used to document the surface flow. A smoke generator system injected smoke into the vortex cores generated by the forebody and leading edge extensions (LEXs). Documentation was provided by onboard still and video, by air-to-air, and by postflight photography. The surface flow visualization techniques revealed laminar separation bubbles near the forebody apex, lines of separation on the forebody and LEX, and regions of attached and separated flow on the wings and fins. The off-surface flow visualization techniques showed the path of the vortex cores on the forebody and LEX as well as the LEX vortex core breakdown location. An interaction between the forebody and LEX vortices was noted. The flow over the surfaces of the vertical tail was categorized into regions of attached, unsteady, or separated flow using flow tufts.

  4. Alpha plus beta annealed and aged Ti-15 Mo alloy for high strength implant applications.

    PubMed

    Disegi, John A; Roach, Michael D; McMillan, Rod D; Shultzabarger, Brian T

    2016-07-04

    Management of femur fractures requires titanium alloy implants that provide a good combination of static strength and ductility plus sufficient high cycle fatigue strength to resist repetitive loading. A research program was initiated to determine whether aging treatments could increase the strength of alpha + beta Ti-15Mo while maintaining acceptable tensile ductility. A pilot heat treating study indicated the best combination of strength and ductility was obtained using an α + β annealing temperature of 705°C ± 10°C followed by an aging treatment of 482°C ± 10°C. EBSD data for four suppliers revealed that the alpha phase ratios ranged from 16.3% to 18.6% and the beta phase ratios ranged from 81.4% to 83.7%. Mean beta grain size diameters ranged between 1.42 and 1.78 µm. Tensile testing qualification data from four suppliers was statistically analyzed and reviewed. Minimum reproducible tensile values were established and incorporated into ASTM F2066-13 implant material standard. Cantilever fatigue testing was performed with proximal femoral nail implants that were fabricated into fully finished implant constructs. Fatigue results for 125°, 130°, and 135° implant constructs met the acceptance criteria regarding the fatigue runout load limits and failure modes that were identified. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  5. Forebody Aerodynamics of the F-18 High Alpha Research Vehicle with Actuated Forebody Strakes

    NASA Technical Reports Server (NTRS)

    Fisher, David F.; Murri, Daniel G.

    2001-01-01

    Extensive pressure measurements and off-surface flow visualization were obtained on the forebody and strakes of the NASA F-18 High Alpha Research Vehicle (HARV) equipped with actuated forebody strakes. Forebody yawing moments were obtained by integrating the circumferential pressures on the forebody and strakes. Results show that large yawing moments can be generated with forebody strakes. At a 50 deg-angle-of-attack, deflecting one strake at a time resulted in a forebody yawing moment control reversal for small strake deflection angles. However, deflecting the strakes differentially about a 20 deg symmetric strake deployment eliminated the control reversal and produced a near linear variation of forebody yawing moment with differential strake deflection. At an angle of attack of 50 deg and for 0 deg and 20 deg symmetric strake deployments, a larger forebody yawing moment was generated by the forward fuselage (between the radome and the apex of the leading-edge extensions) than on the radome where the actuated forebody strakes were located. Cutouts on the flight vehicle strakes that were not on the wind tunnel models are believed to be responsible for deficits in the suction peaks on the flight radome pressure distributions and differences in the forebody yawing moments.

  6. Development of high-stability magnet power supply

    NASA Astrophysics Data System (ADS)

    Choi, W. S.; Kim, M. J.; Jeong, I. W.; Kim, D. E.; Park, H. C.; Park, K. H.

    2016-06-01

    A very stable (≤10 ppm) magnet power supply (MPS) is required in an accelerator to achieve acceptable beam dynamics. Many factors affect the stability of an MPS, so design of the MPS requires much attention to noise-reduction schemes and to good processing of the signals from the feedback stage. This paper describes some design considerations for an MPS installed and operated in the Pohang Accelerator Laboratory: (1) control method, (2) oversampling technology, (3) ground isolation between hardware modules and (4) low-pass filter design to reduce the switching noise and rectifier ripple components, and shows the stability of three designed devices. The MPS design considerations were verified and validated in simulations and experiments. This paper also shows the relationship between stability and measurement aperture time of digital voltage meter 3458 A to measure stability of a current.

  7. Silphenylene elastomers have high thermal stability and tensile strength

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Two polymeric silphenylene ethers, when cured by reactions with ethyl silicates and metal salts at room temperature, form elastomers having excellent thermal stability and tensile properties. The highest tensile strength obtained in a reinforced elastomer was 2800 psi.

  8. Stability of the Acetic Acid-Induced Bladder Irritation Model in Alpha Chloralose-Anesthetized Female Cats

    PubMed Central

    Kullmann, F. Aura; Wells, Grace I.; Langdale, Christopher L.; Zheng, Jihong; Thor, Karl B.

    2013-01-01

    Time- and vehicle-related variability of bladder and urethral rhabdosphincter (URS) activity as well as cardiorespiratory and blood chemistry values were examined in the acetic acid-induced bladder irritation model in α-chloralose-anesthetized female cats. Additionally, bladder and urethra were evaluated histologically using Mason trichrome and toluidine blue staining. Urodynamic, cardiovascular and respiratory parameters were collected during intravesical saline infusion followed by acetic acid (0.5%) to irritate the bladder. One hour after starting acetic acid infusion, a protocol consisting of a cystometrogram, continuous infusion-induced rhythmic voiding contractions, and a 5 min “quiet period” (bladder emptied without infusion) was precisely repeated every 30 minutes. Administration of vehicle (saline i.v.) occurred 15 minutes after starting each of the first 7 cystometrograms and duloxetine (1mg/kg i.v.) after the 8th. Acetic acid infusion into the bladder increased URS-EMG activity, bladder contraction frequency, and decreased contraction amplitude and capacity, compared to saline. Bladder activity and URS activity stabilized within 1 and 2 hours, respectively. Duloxetine administration significantly decreased bladder contraction frequency and increased URS-EMG activity to levels similar to previous reports. Cardiorespiratory parameters and blood gas levels remained consistent throughout the experiment. The epithelium of the bladder and urethra were greatly damaged and edema and infiltration of neutrophils in the lamina propria of urethra were observed. These data provide an ample evaluation of the health of the animals, stability of voiding function and appropriateness of the model for testing drugs designed to evaluate lower urinary tract as well as cardiovascular and respiratory systems function. PMID:24040064

  9. MUC1 mucin stabilizes and activates hypoxia-inducible factor 1 alpha to regulate metabolism in pancreatic cancer

    PubMed Central

    Chaika, Nina V.; Gebregiworgis, Teklab; Lewallen, Michelle E.; Purohit, Vinee; Radhakrishnan, Prakash; Liu, Xiang; Zhang, Bo; Mehla, Kamiya; Brown, Roger B.; Caffrey, Thomas; Yu, Fang; Johnson, Keith R.; Powers, Robert; Hollingsworth, Michael A.; Singh, Pankaj K.

    2012-01-01

    Aberrant glucose metabolism is one of the hallmarks of cancer that facilitates cancer cell survival and proliferation. Here, we demonstrate that MUC1, a large, type I transmembrane protein that is overexpressed in several carcinomas including pancreatic adenocarcinoma, modulates cancer cell metabolism to facilitate growth properties of cancer cells. MUC1 occupies the promoter elements of multiple genes directly involved in glucose metabolism and regulates their expression. Furthermore, MUC1 expression enhances glycolytic activity in pancreatic cancer cells. We also demonstrate that MUC1 expression enhances in vivo glucose uptake and expression of genes involved in glucose uptake and metabolism in orthotopic implantation models of pancreatic cancer. The MUC1 cytoplasmic tail is known to activate multiple signaling pathways through its interactions with several transcription factors/coregulators at the promoter elements of various genes. Our results indicate that MUC1 acts as a modulator of the hypoxic response in pancreatic cancer cells by regulating the expression/stability and activity of hypoxia-inducible factor-1α (HIF-1α). MUC1 physically interacts with HIF-1α and p300 and stabilizes the former at the protein level. By using a ChIP assay, we demonstrate that MUC1 facilitates recruitment of HIF-1α and p300 on glycolytic gene promoters in a hypoxia-dependent manner. Also, by metabolomic studies, we demonstrate that MUC1 regulates multiple metabolite intermediates in the glucose and amino acid metabolic pathways. Thus, our studies indicate that MUC1 acts as a master regulator of the metabolic program and facilitates metabolic alterations in the hypoxic environments that help tumor cells survive and proliferate under such conditions. PMID:22869720

  10. Stability of the acetic acid-induced bladder irritation model in alpha chloralose-anesthetized female cats.

    PubMed

    Kullmann, F Aura; Wells, Grace I; Langdale, Christopher L; Zheng, Jihong; Thor, Karl B

    2013-01-01

    Time- and vehicle-related variability of bladder and urethral rhabdosphincter (URS) activity as well as cardiorespiratory and blood chemistry values were examined in the acetic acid-induced bladder irritation model in α-chloralose-anesthetized female cats. Additionally, bladder and urethra were evaluated histologically using Mason trichrome and toluidine blue staining. Urodynamic, cardiovascular and respiratory parameters were collected during intravesical saline infusion followed by acetic acid (0.5%) to irritate the bladder. One hour after starting acetic acid infusion, a protocol consisting of a cystometrogram, continuous infusion-induced rhythmic voiding contractions, and a 5 min "quiet period" (bladder emptied without infusion) was precisely repeated every 30 minutes. Administration of vehicle (saline i.v.) occurred 15 minutes after starting each of the first 7 cystometrograms and duloxetine (1mg/kg i.v.) after the 8(th). Acetic acid infusion into the bladder increased URS-EMG activity, bladder contraction frequency, and decreased contraction amplitude and capacity, compared to saline. Bladder activity and URS activity stabilized within 1 and 2 hours, respectively. Duloxetine administration significantly decreased bladder contraction frequency and increased URS-EMG activity to levels similar to previous reports. Cardiorespiratory parameters and blood gas levels remained consistent throughout the experiment. The epithelium of the bladder and urethra were greatly damaged and edema and infiltration of neutrophils in the lamina propria of urethra were observed. These data provide an ample evaluation of the health of the animals, stability of voiding function and appropriateness of the model for testing drugs designed to evaluate lower urinary tract as well as cardiovascular and respiratory systems function.

  11. Cyclic analogs of alpha-melanocyte-stimulating hormone (alphaMSH) with high agonist potency and selectivity at human melanocortin receptor 1b.

    PubMed

    Bednarek, Maria A; MacNeil, Tanya; Tang, Rui; Fong, Tung M; Cabello, M Angeles; Maroto, Marta; Teran, Ana

    2008-06-01

    Alpha-melanotropin (alphaMSH), Ac-Ser1-Tyr2-Ser3-Met4-Glu5-His6-Phe7-Arg8-Trp9-Gly10-Lys11-Pro12-Val13-NH2,(1) has been long recognized as an important physiological regulator of skin and hair pigmentation in mammals. Binding of this peptide to the melanocortin receptor 1 (MC1R) leads to activation of tyrosinase, the key enzyme of the melanin biosynthesis pathway. In this study, interactions of the human MC1bR (an isoform of the receptor 1a) with the synthetic cyclic analogs of alphaMSH were studied. These ligands were analogs of MTII, Ac-Nle4-cyclo-(Asp5-His6-D-Phe7-Arg8-Trp9-Lys10)-NH2, a potent pan-agonist at the human melanocortin receptors (hMC1,3-5R). In the structure of MTII, the His6-D-Phe7-Arg8-Trp9 segment has been recognized as "essential" for molecular recognition at the human melanocortin receptors (hMC1,3-5R). Herein, the role of the Trp9 in the ligand interactions with the hMC1b,3-5R has been reevaluated. Analogs with various amino acids in place of Trp9 were synthesized and tested in vitro in receptor affinity binding and cAMP functional assays at human melanocortin receptors 1b, 3, 4 and 5 (hMC1b,3-5R). Several of the new peptides were high potency agonists (partial) at hMC1bR (EC50 from 0.5 to 20 nM) and largely inactive at hMC3-5R. The bulky aromatic side chain in position 9, such as that in Trp, was found not to be essential to agonism (partial) of the studied peptides at hMC1bR.

  12. Stabilization of Thin-Shell Implosions Using a High-Foot Adiabat-Shaped Drive on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Lafon, Marion; Gauthier, Pascal; Masse, Laurent

    2016-10-01

    The High Foot (HF) campaign on the National Ignition Facility (NIF) has improved the neutron yield by an order of magnitude as compared to the implosions reported during the National Ignition Campaign (NIC) while dramatically lowering the ablation-front instability growth. However, this yield increase came at the expense of reduced fuel compression due to higher fuel adiabat. Thinner shell adiabat-shaped HF implosions have been designed to combine the ablation front stability benefits of the current HF pulses with the demonstrated high fuel compressibility of the NIC implosions and increased implosion velocity. This is accomplished by using a hybrid adiabat-shaping technique which both lowers the laser power between the first and second pulses to enhance the ablative stabilization at early times and precisely tailors the rise-to-peak drive to prevent undesired shocks from propagating in the fuel and depositing additional entropy. Ablation front growth factor spectra are generated from two-dimensional simulations with the FCI2 radiation hydrodynamics code. Linear analysis of the instability growth demonstrates that adiabat-shaped pulses provide a path to control and reduce ablation front instability growth while placing the fuel on a lower adiabat to achieve the alpha-heating-dominated regime. Adiabat-shaped pulses without picket are also investigated as a potential way to enhance the stability of the holhraum walls at early times.

  13. Ly-alpha emission from disk absorption systems at high redshift - Star formation in young galaxy disks

    NASA Technical Reports Server (NTRS)

    Smith, Harding E.; Cohen, Ross D.; Burns, Joseph E.; Moore, David J.; Uchida, Barbara A.

    1989-01-01

    Narrow-band imaging observations are reported which were made in an attempt to detect Ly-alpha emission from high-redshift candidate galaxy disk systems discovered as high column density absorbers of background QSOs. For four systems with z = 2.3-2.8, no emission is detected to a limit of about 10 to the -16th ergs/sq cm/s, corresponding to luminosity limits of about 10 exp 42-43 ergs/s for the material producing the absorption. The inferred Ly-alpha luminosities lie one to two orders of magnitude below estimates of the Ly-alpha luminosities for active star-forming epochs of many prescriptions for galaxy formation and also considerably below measured Ly-alpha luminosities for other candidate young galaxies detected in radio surveys. A limiting star-formation rate in these systems of about 2-7 solar masses/yr is set; the limit may be about 10 times larger with small but observationally allowable amounts of dust.

  14. Ly{alpha} EMISSION FROM HIGH-REDSHIFT SOURCES IN COSMOS

    SciTech Connect

    Mallery, Ryan P.; Mobasher, Bahram; Hemmati, Shoubaneh; Capak, Peter; Kakazu, Yuko; Masters, Dan; Scoville, Nick; Scarlata, Claudia; Salvato, Mara; McCracken, Henry

    2012-12-01

    We investigate spectroscopically measured Ly{alpha} equivalent widths (EWs) and escape fractions of 244 sources of which 95 are Lyman break galaxies (LBGs) and 106 Lyman alpha emitters (LAEs) at z {approx} 4.2, z {approx} 4.8, and z {approx} 5.6 selected from intermediate and narrowband observations. The sources were selected from the Cosmic Evolution Survey and observed with the DEIMOS spectrograph. We find that the distribution of EWs shows no evolution with redshift for both the LBG selected sources and the intermediate/narrowband LAEs. We also find that the Ly{alpha} escape fraction of intermediate/narrowband LAEs is on average higher and has a larger variation than the escape fraction of LBG selected sources. The escape fraction does not show a dependence with redshift. Similar to what has been found for LAEs at low redshifts, the sources with the highest extinctions show the lowest escape fractions. The range of escape fractions increases with decreasing extinction. This is evidence that the dust extinction is the most important factor affecting the escape of Ly{alpha} photons, but at low extinctions other factors, such as the H I covering fraction and gas kinematics, can be just as effective at inhibiting the escape of Ly{alpha} photons.

  15. Stabilized porous liposomes with encapsulated Gd-labeled dextran as highly efficient MRI contrast agents

    PubMed Central

    Zaki, Ajlan Al; Jones, Ian W.; Hall, Henry K.; Aspinwall, Craig A; Tsourkas, Andrew

    2014-01-01

    A highly efficient contrast agent for magnetic resonance imaging was developed by encapsulating gadolinium within a stabilized porous liposome. The highly porous membrane leads to a high relaxivity of the encapsulated Gd. The stability of the liposome was improved by forming a polymer network within the bilayer membrane. PMID:24457826

  16. High resolution alpha particle detectors based on 4H-SiC epitaxial layer

    NASA Astrophysics Data System (ADS)

    Zat'ko, B.; Dubecký, F.; Šagátová, A.; Sedlačová, K.; Ryć, L.

    2015-04-01

    We fabricated and characterized 4H-SiC Schottky diodes as a spectrometric detector of alpha particles. A thin blocking contact of Ni/Au (15 nm) was used to minimize the influence on alpha particles energy. Current-voltage characteristics of the detector were measured and a low current density below 0.3 nAcm-2 was observed at room temperature. 239Pu241Am244Cm was used as a source of alpha particles within the energy range between 5.1 MeV and 5.8 MeV for detector testing. The charge collection efficiency close to 100 % at reverse bias exceeding 50 V was determined. The best spectrometric performance shows a pulse height spectrum at a reverse bias of 200 V giving an energy resolution of 0.25 % in the full width and half maximum for 5.486 MeV of 241Am.

  17. Cryogenic microcalorimeter system for ultra-high resolution alpha-particle spectrometry

    SciTech Connect

    Rabin, Michael W; Hoover, Andrew S; Bacrania, Mnesh K; Croce, Mark P; Hoteling, N J; Lamont, S P; Plionis, A A; Dry, D E; Ullom, J N; Bennett, D A; Horansky, R; Kotsubo, V; Cantor, R

    2009-01-01

    Microcalorimeters have been shown to yield unsurpassed energy resolution for alpha spectrometry, up to 1.06 keV FWHM at 5.3 MeV. These detectors use a superconducting transition-edge sensor (TES) to measure the temperature change in an absorber from energy deposited by an interacting alpha particle. Our system has four independent detectors mounted inside a liquid nitrogen/liquid helium cryostat. An adiabatic demagnetization refrigerator (ADR) cools the detector stage to its operating temperature of 80 mK. Temperature regulation with {approx}15 uK peak-to-peak variation is achieved by PID control of the ADR. The detectors are voltage-biased, and the current signal is amplified by a commercial SQUID readout system and digitized for further analysis, This paper will discuss design and operation of our microcalorimeter alpha spectrometer, and will show recent results.

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

    SciTech Connect

    Hughes, M.H.; Phillips, M.W.

    1996-01-01

    This report describes MHD equilibrium and stability studies carried out at Northrop Grumman`s Advanced Technology and Development Center during the period March 1 to December 31, 1995. Significant progress is reported in both ideal and resistive MHD modeling of TFTR plasmas. Specifically, attention is concentrated on analysis of Advanced Tokamak experiments at TFTR involving plasmas in which the q-profiles were non-monotonic.

  19. Are integrin alpha(2)beta(1), glycoprotein Ib and vWf levels correlated with their contributions to platelet adhesion on collagen under high-shear flow?

    PubMed

    Jung, Stephanie M; Sonoda, Mamiko; Tsuji, Kayoko; Jimi, Atsuo; Nomura, Shosaku; Kanaji, Taisuke; Moroi, Masaaki

    2010-01-01

    Platelets in flowing blood at high-shear stress are recruited to exposed subendothelial collagen of injured vessels by GPIb-von Willebrand factor (vWf) and integrin alpha(2)beta(1) (alpha(2)beta(1))-collagen interactions. Platelet adhesion to type I collagen depends mainly on the alpha(2)beta(1)-collagen interaction and that to type III collagen depends on the GPIb-vWf interaction due to vWf's weak affinity for type I collagen. Contributions of these two interactions would differ depending on expressions of alpha(2)beta(1), vWf, or GPIb. We quantitated platelet adhesion to low- and high-density collagen under high-shear flow conditions in the presence of anti-alpha(2)beta(1) (Gi9) and anti-GPIb (NNKY5-5) antibodies to determine if their inhibitory effects were correlated with the amounts of alpha(2)beta(1), GPIb and vWf. Gi9 inhibition of adhesion to type I collagen was decreased in platelets with more integrin alpha(2)beta(1). Gi9 and NNKY5-5 are more inhibitory against adhesion to low-density type III and I, respectively. Higher alpha(2)beta(1) expression decreases adhesion to low-density type III and increases Gi9 inhibition of adhesion to high-density type III, suggesting crosstalk between the alpha(2)beta(1)-collagen and GPIb-vWf interactions in adhesion to type III. Integrin alpha(2)beta(1)-collagen and GPIb-vWf interactions both contribute to platelet adhesion to collagen under high-shear flow. In adhesion under high-shear stress, the two interactions would compensate for each other, when there is a deficiency in one or the other. The alpha(2)beta(1)-collagen interaction was also suggested to have an inhibitory effect on platelet adhesion to type III collagen, through a yet undefined mechanism.

  20. [Determination of alpha-arbutin, beta-arbutin and niacinamide in cosmetics by high performance liquid chromatography].

    PubMed

    Cheng, Peng; Chen, Meilan; Zhu, Yan

    2010-01-01

    A high performance liquid chromatography (HPLC) method for the determination of two optical isomers of arbutin (alpha-arbutin and beta-arbutin) and niacinamide in cosmetics was developed. The samples were extracted by the mixture of salt water and chloroform (2:1, v/v). The separation was performed on an ODS-BP column (200 mm x 4.6 mm, 5 microm, Elite) with methanol-water (10:90, v/v) as the mobile phase at a flow rate of 0.5 mL/min and 25 degrees C. The detection wavelength was set at 220 nm and the sample injection volume was 20 microL. There were good linear relationships between the mass concentration and the peak areas of alpha-arbutin, beta-arbutin and niacinamide in the ranges of 0.07-50, 0.06-50 and 0.05-50 mg/L, respectively. The relative standard deviations (RSDs, n = 7) of alpha-arbutin, beta-arbutin and niacinamide were 1.65%, 1.73% and 1.33%, respectively. The proposed method has been applied for the determination of alpha-arbutin, beta-arbutin and niacinamide in cosmetics with recoveries of 91.7%-109.6%. This method is rapid, simple and suitable for the detection of whitening ingredients in cosmetic.

  1. Development of a high-speed H-alpha camera system for the observation of rapid fluctuations in solar flares

    NASA Technical Reports Server (NTRS)

    Kiplinger, Alan L.; Dennis, Brian R.; Orwig, Larry E.; Chen, P. C.

    1988-01-01

    A solid-state digital camera was developed for obtaining H alpha images of solar flares with 0.1 s time resolution. Beginning in the summer of 1988, this system will be operated in conjunction with SMM's hard X-ray burst spectrometer (HXRBS). Important electron time-of-flight effects that are crucial for determining the flare energy release processes should be detectable with these combined H alpha and hard X-ray observations. Charge-injection device (CID) cameras provide 128 x 128 pixel images simultaneously in the H alpha blue wing, line center, and red wing, or other wavelength of interest. The data recording system employs a microprocessor-controlled, electronic interface between each camera and a digital processor board that encodes the data into a serial bitstream for continuous recording by a standard video cassette recorder. Only a small fraction of the data will be permanently archived through utilization of a direct memory access interface onto a VAX-750 computer. In addition to correlations with hard X-ray data, observations from the high speed H alpha camera will also be correlated and optical and microwave data and data from future MAX 1991 campaigns. Whether the recorded optical flashes are simultaneous with X-ray peaks to within 0.1 s, are delayed by tenths of seconds or are even undetectable, the results will have implications on the validity of both thermal and nonthermal models of hard X-ray production.

  2. Purification and characterization of a novel fungal alpha-glucosidase from Mortierella alliacea with high starch-hydrolytic activity.

    PubMed

    Tanaka, Yoshio; Aki, Tsunehiro; Hidaka, Yûki; Furuya, Yûji; Kawamoto, Seiji; Shigeta, Seiko; Ono, Kazuhisa; Suzuki, Osamu

    2002-11-01

    The fungal strain Mortierella alliacea YN-15 is an arachidonic acid producer that assimilates soluble starch despite having undetectable alpha-amylase activity. Here, a alpha-glucosidase responsible for the starch hydrolysis was purified from the culture broth through four-step column chromatography. Maltose and other oligosaccharides were less preferentially hydrolyzed and were used as a glucosyl donor for transglucosylation by the enzyme, demonstrating distinct substrate specificity as a fungal alpha-glucosidase. The purified enzyme consisted of two heterosubunits of 61 and 31 kDa that were not linked by a covalent bond but stably aggregated to each other even at a high salt concentration (0.5 M), and behaved like a single 92-kDa component in gel-filtration chromatography. The hydrolytic activity on maltose reached a maximum at 55 degrees C and in a pH range of 5.0-6.0, and in the presence of ethanol, the transglucosylation reaction to form ethyl-alpha-D-glucoside was optimal at pH 5.0 and a temperature range of 45-50 degrees C.

  3. K-alpha x-ray source using high energy and high repetition rate laser system for phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Serbanescu, Cristina; Fourmaux, Sylvain; Kieffer, Jean-Claude; Kincaid, Russell; Krol, Andrzej

    2009-08-01

    K-alpha x-ray sources from laser produced plasmas provide completely new possibilities for x-ray phase-contrast imaging applications. By tightly focusing intense femtosecond laser pulses onto a solid target, K-alpha x-ray pulses are generated through the interaction of energetic electrons created in the plasma with the bulk target. In this paper, we present a continuous and efficient Mo K-alpha x-ray source produced by a femtosecond laser system operating at 100 Hz repetition rate with maximum pulse energy of 110 mJ before compression. The source has x-ray conversion efficiency greater than 10-5 into K-alpha line emission. In preparation for phase contrast imaging applications, the size of the resultant K-alpha x-ray emission spot has been also characterized. The source exhibits sufficient spatial coherence to observe phase contrast. We observe a relatively small broadening of the K-alpha source size compared to the size of the laser beam itself. Detailed characterization of the source including the x-ray spectrum and the x-ray average yield along with phase contrast images of test objects will be presented.

  4. Water-in-silicone oil emulsion stabilizing surfactants formed from native albumin and alpha,omega-triethoxysilylpropyl-polydimethylsiloxane.

    PubMed

    Zelisko, Paul M; Flora, Kulwinder K; Brennan, John D; Brook, Michael A

    2008-08-01

    Contact with hydrophobic silicones frequently leads to protein denaturation. However, it is demonstrated that albumin in water-in-silicone oil emulsions retains its native structure in the presence of a functional, triethoxysilyl-terminated silicone polymer, TES-PDMS. Both HSA and TES-PDMS were essential for the formation of stable water-in-silicone oil emulsions: attempts to generate stable emulsions using independently either the protein or the functionalized silicone as a surfactant failed. Confocal microscopy indicated that the human serum albumin (HSA) preferentially adsorbed at the oil/water interface, even in the presence of another protein (glucose oxidase). A variety of experiments demonstrated that the hydrolysis of the Si-OEt groups on the functional silicone occurred only to a limited extent, consistent with the absence of a covalent linkage between the silicone and protein, or of cross-linked silicones at the interface. The fluorescence spectra of HSA extracted from the emulsions, front-faced fluorescence experiments on the HSA/silicone emulsion itself, and HSA/salicylate binding studies all demonstrated that the stability of the water/oil interface decreased as the protein began to unfold: unfolding of the protein in the emulsion was slower than in aqueous solution. The experimental evidence indicated that the interaction between HSA and TES-PDMS is not associated with either homomolecular (HSA/HSA; TES-PDMS/TES-PDMS) interactions or with covalent linkage between two the polymers. Rather, the data is consistent with the direct binding of unhydrolyzed Si(OEt) 3 groups to native HSA. The nature of these interactions is discussed.

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

    NASA Technical Reports Server (NTRS)

    Mohler, R. R.

    1993-01-01

    This project is intended to research and develop new nonlinear methodologies for the control and stability analysis of high-performance, high angle-of-attack aircraft such as HARV (F18). Past research (reported in our Phase 1, 2, and 3 progress reports) is summarized and more details of final Phase 3 research is provided. While research emphasis is on nonlinear control, other tasks such as associated model development, system identification, stability analysis, and simulation are performed in some detail as well. An overview of various models that were investigated for different purposes such as an approximate model reference for control adaptation, as well as another model for accurate rigid-body longitudinal motion is provided. Only a very cursory analysis was made relative to type 8 (flexible body dynamics). Standard nonlinear longitudinal airframe dynamics (type 7) with the available modified F18 stability derivatives, thrust vectoring, actuator dynamics, and control constraints are utilized for simulated flight evaluation of derived controller performance in all cases studied.

  6. A Highly Conserved Residue in HIV-1 Nef Alpha Helix 2 Modulates Protein Expression

    PubMed Central

    Johnson, Aaron L.; Dirk, Brennan S.; Coutu, Mathieu; Haeryfar, S. M. Mansour; Arts, Eric J.; Finzi, Andrés

    2016-01-01

    ABSTRACT Extensive genetic diversity is a defining characteristic of human immunodeficiency virus type 1 (HIV-1) and poses a significant barrier to the development of an effective vaccine. To better understand the impact of this genetic diversity on the HIV-1 pathogenic factor Nef, we compiled a panel of reference strains from the NIH Los Alamos HIV Database. Initial sequence analysis identified point mutations at Nef residues 13, 84, and 92 in subtype C reference strain C.BR92025 from Brazil. Functional analysis revealed impaired major histocompatibility complex class I and CD4 downregulation of strain C.BR92025 Nef, which corresponded to decreased protein expression. Metabolic labeling demonstrated that strain C.BR92025 Nef has a greater rate of protein turnover than subtype B reference strain B.JRFL that, on the basis of mutational analysis, is related to Nef residue A84. An alanine-to-valine substitution at position 84, located in alpha helix 2 of Nef, was sufficient to alter the rate of turnover of an otherwise highly expressed Nef protein. In conclusion, these findings highlight HIV-1 Nef residue A84 as a major determinant of protein expression that may offer an additional avenue to disrupt or mediate the effects of this key HIV-1 pathogenic factor. IMPORTANCE The HIV-1 Nef protein has been established as a key pathogenic determinant of HIV/AIDS, but there is little knowledge of how the extensive genetic diversity of HIV-1 affects Nef function. Upon compiling a set of subtype-specific reference strains, we identified a subtype C reference strain, C.BR92025, that contained natural polymorphisms at otherwise highly conserved residues 13, 84, and 92. Interestingly, strain C.BR92025 Nef displayed impaired Nef function and had decreased protein expression. We have demonstrated that strain C.BR92025 Nef has a higher rate of protein turnover than highly expressed Nef proteins and that this higher rate of protein turnover is due to an alanine-to-valine substitution

  7. Estrogen receptor alpha somatic mutations Y537S and D538G confer breast cancer endocrine resistance by stabilizing the activating function-2 binding conformation

    PubMed Central

    Fanning, Sean W; Mayne, Christopher G; Dharmarajan, Venkatasubramanian; Carlson, Kathryn E; Martin, Teresa A; Novick, Scott J; Toy, Weiyi; Green, Bradley; Panchamukhi, Srinivas; Katzenellenbogen, Benita S; Tajkhorshid, Emad; Griffin, Patrick R; Shen, Yang; Chandarlapaty, Sarat; Katzenellenbogen, John A; Greene, Geoffrey L

    2016-01-01

    Somatic mutations in the estrogen receptor alpha (ERα) gene (ESR1), especially Y537S and D538G, have been linked to acquired resistance to endocrine therapies. Cell-based studies demonstrated that these mutants confer ERα constitutive activity and antiestrogen resistance and suggest that ligand-binding domain dysfunction leads to endocrine therapy resistance. Here, we integrate biophysical and structural biology data to reveal how these mutations lead to a constitutively active and antiestrogen-resistant ERα. We show that these mutant ERs recruit coactivator in the absence of hormone while their affinities for estrogen agonist (estradiol) and antagonist (4-hydroxytamoxifen) are reduced. Further, they confer antiestrogen resistance by altering the conformational dynamics of the loop connecting Helix 11 and Helix 12 in the ligand-binding domain of ERα, which leads to a stabilized agonist state and an altered antagonist state that resists inhibition. DOI: http://dx.doi.org/10.7554/eLife.12792.001 PMID:26836308

  8. Ultra-High Pressure Homogenization improves oxidative stability and interfacial properties of soy protein isolate-stabilized emulsions.

    PubMed

    Fernandez-Avila, C; Trujillo, A J

    2016-10-15

    Ultra-High Pressure Homogenization (100-300MPa) has great potential for technological, microbiological and nutritional aspects of fluid processing. Its effect on the oxidative stability and interfacial properties of oil-in-water emulsions prepared with 4% (w/v) of soy protein isolate and soybean oil (10 and 20%, v/v) were studied and compared to emulsions treated by conventional homogenization (15MPa). Emulsions were characterized by particle size, emulsifying activity index, surface protein concentration at the interface and by transmission electron microscopy. Primary and secondary lipid oxidation products were evaluated in emulsions upon storage. Emulsions with 20% oil treated at 100 and 200MPa exhibited the most oxidative stability due to higher amount of oil and protein surface load at the interface. This manuscript addresses the improvement in oxidative stability in emulsions treated by UHPH when compared to conventional emulsions.

  9. High-yield synthesis of well-crystalline alpha-Fe2O3 nanoparticles: structural, optical and photocatalytic properties.

    PubMed

    Umar, Ahmad; Abaker, M; Faisal, M; Hwang, S W; Baskoutas, S; Al-Sayari, S A

    2011-04-01

    In this paper, the high-yield facile synthesis, detailed characterization and photocatalytic application of alpha-Fe2O3 nanoparticles are reported. The synthesis was done via simple hydrothermal process by using aqueous mixtures of iron chloride, hexamethylenediamine and NH3 x H2O at 110 degrees C. The morphologies of the synthesized products were examined by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) which confirmed that the synthesized structures are almost spherical shaped nanoparticles with the average diameters of -35 +/- 5 nm, and are grown in high yield. The detailed structural characterizations and composition of the as-synthesized nanoparticles were investigated by using X-ray diffraction (XRD), high-resolution TEM (HRTEM), energy dispersive spectroscopy (EDS) attached with FESEM and Fourier transform infrared spectroscopy (FTIR) which substantiated that the as-synthesized nanoparticles are well crystalline and pure alpha-Fe2O3. The UV-Vis absorption spectrum of the synthesized nanoparticles demonstrated the existence of two optical band gaps which correspond to direct and indirect transitions, respectively. The as-synthesized alpha-Fe2O3 nanoparticles exhibit good photocatalytic properties on photocatalytic degradation of methylene blue.

  10. Highly enantioselective alpha-chlorination of cyclic beta-ketoesters catalyzed by N,N'-dioxide using NCS as the chlorine source.

    PubMed

    Cai, Yunfei; Wang, Wentao; Shen, Ke; Wang, Jun; Hu, Xiaolei; Lin, Lili; Liu, Xiaohua; Feng, Xiaoming

    2010-02-28

    A simple and highly efficient N,N'-dioxide organocatalyst system was developed for the asymmetric alpha-chlorination of cyclic beta-ketoesters using easily available NCS as the chlorine source to provide a series of optically active alpha-chloro-beta-ketoesters in excellent yields with 90-98% ee.

  11. Protective mechanism of the Mexican bean weevil against high levels of alpha-amylase inhibitor in the common bean.

    PubMed

    Ishimoto, M; Chrispeels, M J

    1996-06-01

    Alpha-amylase inhibitor (alpha AI) protects seeds of the common bean (Phaseolus vulgaris) against predation by certain species of bruchids such as the cowpea weevil (Callosobruchus maculatus) and the azuki bean weevil (Callosobruchus chinensis), but not against predation by the bean weevil (Acanthoscelides obtectus) or the Mexican bean weevil (Zabrotes subfasciatus), insects that are common in the Americas. We characterized the interaction of alpha AI-1 present in seeds of the common bean, of a different isoform, alpha AI-2, present in seeds of wild common bean accessions, and of two homologs, alpha AI-Pa present in seeds of the tepary bean (Phaseolus acutifolius) and alpha AI-Pc in seeds of the scarlet runner bean (Phaseolus coccineus), with the midgut extracts of several bruchids. The extract of the Z. subfasciatus larvae rapidly digests and inactivates alpha AI-1 and alpha AI-Pc, but not alpha AI-2 or alpha AI-Pa. The digestion is caused by a serine protease. A single proteolytic cleavage in the beta subunit of alpha AI-1 occurs at the active site of the protein. When degradation is prevented, alpha AI-1 and alpha AI-Pc do not inhibit the alpha-amylase of Z. subfasciatus, although they are effective against the alpha-amylase of C. chinensis. Alpha AI-2 and alpha AI-Pa, on the other hand, do inhibit the alpha-amylase of Z. subfasciatus, suggesting that they are good candidates for genetic engineering to achieve resistance to Z. subfasciatus.

  12. Metal Chelating Crosslinkers Form Nanogels with High Chelation Stability.

    PubMed

    Lux, Jacques; Chan, Minnie; Elst, Luce Vander; Schopf, Eric; Mahmoud, Enas; Laurent, Sophie; Almutairi, Adah

    2013-12-14

    We present a series of hydrogel nanoparticles (nanogels) incorporating either acyclic or cyclic metal chelates as crosslinkers. These crosslinkers are used to formulate polyacrylamide-based nanogels (diameter 50 to 85 nm) yielding contrast agents with enhanced relaxivities (up to 6-fold greater than Dotarem®), because this nanogel structure slows the chelator's tumbling frequency and allows fast water exchange. Importantly, these nanogels also stabilize Gd(3+) within the chelator thermodynamically and kinetically against metal displacement through transmetallation, which should reduce toxicity associated with release of free Gd(3+). This chelation stability suggests that the chelate crosslinker strategy may prove useful for other applications of metal-chelating nanoparticles in medicine, including other imaging modalities and radiotherapy.

  13. Metal Chelating Crosslinkers Form Nanogels with High Chelation Stability

    PubMed Central

    Elst, Luce Vander; Schopf, Eric; Mahmoud, Enas; Laurent, Sophie; Almutairi, Adah

    2013-01-01

    We present a series of hydrogel nanoparticles (nanogels) incorporating either acyclic or cyclic metal chelates as crosslinkers. These crosslinkers are used to formulate polyacrylamide-based nanogels (diameter 50 to 85 nm) yielding contrast agents with enhanced relaxivities (up to 6-fold greater than Dotarem®), because this nanogel structure slows the chelator's tumbling frequency and allows fast water exchange. Importantly, these nanogels also stabilize Gd3+ within the chelator thermodynamically and kinetically against metal displacement through transmetallation, which should reduce toxicity associated with release of free Gd3+. This chelation stability suggests that the chelate crosslinker strategy may prove useful for other applications of metal-chelating nanoparticles in medicine, including other imaging modalities and radiotherapy. PMID:24505553

  14. Stability of the high-temperature G-16 primer composition

    SciTech Connect

    Durand, N.A.; Weinmaster, R.R.; Massis, T.A.; Fleming, W.

    1988-01-01

    The stability of the G-16 pyrotechnic primer mixture of antimony sulfide, calcium silicide, and potassium chlorate was studied at temperatures up to 200/sup 0/C in sealed and open environments. Data have shown that this mixture is stable in open environments at 200/sup 0/C for up to 48 hours. However, in sealed, limited volume environments, the mixture completely decomposes within 24 hours at 200/sup 0/C. In sealed environments, the mixture shows stability with copper present. Both functional testing and chemical analysis were used to evaluate the primer composition after temperature exposure. The degree of degradation of the mixture was determined from the concentration of final reaction products (sulfate and chloride ions), using ion chromatography. When copper was present, the intermediate reaction products were scavenged by the copper, and the degradation was reduced. The role of copper in the reaction was verified with differential scanning calorimetry and surface analysis. 3 refs., 9 figs., 2 tabs.

  15. Infrastructure stability surveillance with high resolution InSAR

    NASA Astrophysics Data System (ADS)

    Balz, Timo; Düring, Ralf

    2017-02-01

    The construction of new infrastructure in largely unknown and difficult environments, as it is necessary for the construction of the New Silk Road, can lead to a decreased stability along the construction site, leading to an increase in landslide risk and deformation caused by surface motion. This generally requires a thorough pre-analysis and consecutive surveillance of the deformation patterns to ensure the stability and safety of the infrastructure projects. Interferometric SAR (InSAR) and the derived techniques of multi-baseline InSAR are very powerful tools for a large area observation of surface deformation patterns. With InSAR and deriver techniques, the topographic height and the surface motion can be estimated for large areas, making it an ideal tool for supporting the planning, construction, and safety surveillance of new infrastructure elements in remote areas.

  16. High temperature stability multilayers for EUV condenser optics

    SciTech Connect

    Bajt, S; Stearns, D G

    2005-05-03

    We investigate the thermal stability of Mo/SiC multilayer coatings at elevated temperatures. Transmission electron microscopy and x-ray diffraction studies show that upon annealing a thermally-induced structural relaxation occurs that transforms the polycrystalline Mo and amorphous SiC layers in as-deposited multilayers into amorphous Mo-Si-C alloy and crystalline SiC, respectively. After this relaxation process is complete the multilayer is stable at temperatures up to 400 C.

  17. X-ray and optical crystallographic parameters investigations of high frequency induction melted Al-(alpha-Al(2)O(3)) alloys.

    PubMed

    Bourbia, A; Draissia, M; Bedboudi, H; Boulkhessaim, S; Debili, M Y

    2010-01-01

    This article deals with the microstructural strengthening mechanisms of aluminium by means of hard alpha-Al(2)O(3) alumina fine particles. A broad of understanding views covering materials preparations, elaboration process, characterization techniques and associated microstructural characteristic parameters measurements is given. In order to investigate the microstructural characteristic parameters and the mechanical strengthening mechanisms of pure aluminium by hard fine particles, a set of Al-(alpha-Al(2)O(3)) alloys samples were made under vacuum by high fusion temperature melting, the high frequency (HF) process, and rapidly solidified under ambient temperature from a mixture of cold-compacted high-pure fine Al and alpha-Al(2)O(3) powders. The as-solidified Al-(alpha-Al(2)O(3)) alloys were characterized by means of X-ray diffraction (XRD) analyses, optical microscopy observations and Vickers microhardness tests in both brut and heat-treated states. It was found that the as-solidified HF Al-(alpha-Al(2)O(3)) alloys with compositions below 4 wt.% (alpha-Al(2)O(3)) are single-phase microstructures of the solid solution FCC Al phase and over two-phase microstructures of the solid solution FCC Al and the Rhombohedral alpha-Al(2)O(3) phases. The optical micrographs reveal the presence of a grain size refinement in these alloys. Vickers microhardness of the as-solidified Al-(alpha-Al(2)O(3)) is increased by means of pure fine alpha-Al(2)O(3) alumina particles. These combined effects of strengthening and grain size refinement observed in the as-solidified Al-(alpha-Al(2)O(3)) alloys are essentially due to a strengthening of Al by the alpha-Al(2)O(3) alumina particles insertion in the (HF) melted and rapidly solidified alloys.

  18. Creating high-stability high-precision bipolar trim power supply

    SciTech Connect

    Chen, Zhe; Merz, William A.

    2012-07-01

    Thomas Jefferson National Accelerator Facility (TJNAF) is founded by the US Department of Energy (DOE) office of science for the technology advancement and physics research in electron beam accelerator. This facility has the state of the art technology to carry out world-class cutting-edge experiments for the nucleus composition and atomic characteristics identification and exploration for the nature of the matter in the universe. A continuous wave electron beam is featured for such experiments, thus precise and stable trim power supply is required to meet such purpose. This paper demonstrates the challenges and solutions to design, assemble, fabrication and test such high-precision high-stability power supplies. This paper presents the novel design and first article test of the ±20A ±75V bipolar, 100ppm stability level current-regulated high-power trim power supplies for the beam manipulation. This special design can provide valuable documentation and reference values for future designs and special applications in particle accelerator power supply creation.

  19. An S-band high gain relativistic klystron amplifier with high phase stability

    SciTech Connect

    Wu, Y.; Li, Z. H.; Xu, Z.; Ma, Q. S.; Xie, H. Q.

    2014-11-15

    For the purpose of coherent high power microwave combining, an S-band high gain relativistic klystron amplifier with high phase stability is presented and studied. By the aid of 3D particle-in-cell code and circuit simulation software, the mechanism of parasitic oscillation in the device is investigated. And the RF lossy material is adopted in the simulation and experiment to suppress the oscillation. The experimental results show that with an input RF power of 10 kW, a microwave pulse with power of 1.8 GW is generated with a gain of 52.6 dB. And the relative phase difference fluctuation between output microwave and input RF signal is less than ±10° in 90 ns.

  20. Stabilized high-power laser system for the gravitational wave detector advanced LIGO.

    PubMed

    Kwee, P; Bogan, C; Danzmann, K; Frede, M; Kim, H; King, P; Pöld, J; Puncken, O; Savage, R L; Seifert, F; Wessels, P; Winkelmann, L; Willke, B

    2012-05-07

    An ultra-stable, high-power cw Nd:YAG laser system, developed for the ground-based gravitational wave detector Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory), was comprehensively characterized. Laser power, frequency, beam pointing and beam quality were simultaneously stabilized using different active and passive schemes. The output beam, the performance of the stabilization, and the cross-coupling between different stabilization feedback control loops were characterized and found to fulfill most design requirements. The employed stabilization schemes and the achieved performance are of relevance to many high-precision optical experiments.

  1. Alpha slow-moving high-density-lipoprotein subfraction in serum of a patient with radiation enteritis and peritoneal carcinosis

    SciTech Connect

    Peynet, J.; Legrand, A.; Messing, B.; Thuillier, F.; Rousselet, F.

    1989-04-01

    An alpha slow-moving high-density-lipoprotein (HDL) subfraction was seen in a patient presenting with radiation enteritis and peritoneal carcinosis, who was given long-term cyclic parenteral nutrition. This subfraction, observed in addition to normal HDL, was precipitated with low-density lipoproteins (LDL) and very-low-density lipoproteins (VLDL) by sodium phosphotungstate-magnesium chloride. The patient's serum lipoproteins were analyzed after fractionation by density gradient ultracentrifugation. The alpha slow-moving HDL floated in the ultracentrifugation subfractions with densities ranging from 1.028 to 1.084 kg/L, and their main apolipoproteins included apolipoprotein E in addition to apolipoprotein A-I. These HDL were larger than HDL2. The pathogenesis of this unusual HDL subfraction is hypothesized.

  2. Radiation Stability of Triple Coatings Based on Transition-Metal Nitrides Under Irradiation By Alpha Particles and Argon Ions

    NASA Astrophysics Data System (ADS)

    Potekaev, A. I.; Kislitsyn, S. B.; Uglov, V. V.; Klopotov, A. A.; Gorlachev, I. D.; Klopotov, V. D.; Grinkevich, L. S.

    2016-05-01

    The data on the influence of irradiation of (Ti, Cr)N1-x coatings by helium and argon ions on their surface structure are presented. The (Ti, Cr)N1-x coatings 50-300 nm in thickness were formed on carbon steel substrates by vacuum-arc deposition. Irradiation of the coated specimens was performed in a DC-60 heavy-ion accelerator by low-energy 4He+1, 4He+2 and 40Ar5+ ions and high-energy 40Ar5+ ions up to the fluence 1.0·1017 ion/cm2 at the irradiation temperature not higher than 150°C. It is shown that irradiation of the (Ti, Cr)N1-x coating surface by 4He+1, 4He+2 and 40Ar5+ ions with the energy 20 keV/charge does not give rise to any noticeable structural changes nor any surface blistering, while its irradiation by 40Ar5+ ions with the energy 1.50 MeV/amu causes blistering.

  3. Waste minimization through high-pressure microwave digestion of soils for gross {alpha}/{beta} analyses

    SciTech Connect

    Yaeger, J.S.; Smith, L.L.

    1995-04-01

    As a result of the U.S. Department of Energy`s (DOE) environmental restoration and waste management activities, laboratories receive numerous analytical requests for gross {alpha}/{beta} analyses. Traditional sample preparation methods for gross {alpha}/{beta} analysis of environmental and mixed waste samples require repetitive leaching, which is time consuming and generates large volumes of secondary wastes. An alternative to leaching is microwave digestion. In the past. microwave technology has had limited application in the radiochemical laboratory because of restrictions on sample size resulting from vessel pressure limitations. However, new microwave vessel designs allow for pressures on the order of 11 MPa (1500 psi). A procedure is described in which microwave digestion is used to prepare environmental soil samples for gross {alpha}/{beta} analysis. Results indicate that the described procedure meets performance requirements for several soil types and is equivalent to traditional digestion techniques. No statistical differences at the 95% confidence interval exist between the measurement on samples prepared from the hot plate and microwave digestion procedures for those soils tested. Moreover, microwave digestion allows samples to be prepared in a fraction of the time with significantly less acid and with lower potential of cross-contamination. In comparison to the traditional hot plate method, the waste volumes required for the microwave procedure are a factor of 10 lower, while the analyst time for sample processing is at least a factor of three lower.

  4. High TNF-alpha plasma levels and macrophages iNOS and TNF-alpha expression as risk factors for painful diabetic neuropathy

    PubMed Central

    Purwata, Thomas Eko

    2011-01-01

    Painful diabetic neuropathy (PDN) is one of the most common complications of diabetes mellitus. Recently it has become clear that nitric oxide (NO) and proinflammatory cytokines play an important role in the pathogenesis of PDN. We investigated whether the cytokine tumor necrosis factor alpha (TNF-α) and NO play a role in PDN pathogenesis by performing a cross-sectional and a case–control study in 110 type 2 diabetic patients. Of 110 subjects, 59 patients suffered from PDN (cases) and the remaining were painless DN (controls). Cross-sectionally, plasma TNF-α levels and immunoreactivity for inducible NO synthase (iNOS) and TNF-α were higher in patients with more severe pain on the visual analog scale. There were statistically significant differences between mild and severe pain for TNF-α levels, iNOS immunoreactivity, and TNF-α immunoreactivity. There were statistically significant differences between mild and severe pain for TNF-α levels (mean 15.24 pg/mL ± 5.42 vs 20.44 ± 10.34), iNOS immunoreactivity (9.76% ± 8.60% vs 15.48% ± 11.56%), and TNF-α immunoreactivity (13.0% ± 9.48% vs 20.44% ± 11.75%). The case–control study showed that TNF-α had an odds ratio of 5.053 (P < 0.001), TNF-α immunoreactivity of 4.125 (P < 0.001), and iNOS immunoreactivity of 3.546 (P = 0.002). DN patients with high TNF-α levels, and high iNOS and TNF-α expression in macrophages are at risk of suffering from pain. The higher the TNF-α level, and iNOS and TNF-α immunoreactivity, the more severe the pain. These findings could form the basis of further research into better management of PDN. PMID:21811392

  5. Flight Investigation using Variable-Stability Airplanes of Minimum Stability Requirements for High-Speed, High-Altitude Vehicles

    NASA Technical Reports Server (NTRS)

    McFadden, Norman M.; Vomaske, Richard F.; Heinle, Donovan R.

    1961-01-01

    The pilot opinion of the flying qualities of vehicles covering a wide range of longitudinal dynamic characteristics has been determined by the use of a variable-stability airplane. Particular emphasis has been placed on determining the minimum level of stability and control characteristics that the pilot can cope with. There was considerable pilot learning associated with operation in the regions of poor stability characteristics. In the statically stable region the maximum acceptable value of time to damp to half amplitude of the longitudinal mode for normal operation was about 1 second. For emergency conditions the damping could be reduced to zero over most of the frequency range. The extreme lim it of controllability corresponded to a time to double amplitude of the oscillation of about 1 - 1/2 seconds. In the statically unstable region somewhat shorter times to double amplitude were acceptable to the pilots. The boundary for emergency operation corresponded roughly to time to double amplitude of about 2/3 second and the limit of controllability of about l/3 second.

  6. Magnetoliposomes with high USPIO entrapping efficiency, stability and magnetic properties.

    PubMed

    Skouras, Athanasios; Mourtas, Spyridon; Markoutsa, Eleni; De Goltstein, Marie-Christine; Wallon, Claire; Catoen, Sarah; Antimisiaris, Sophia G

    2011-10-01

    The DRV technique (followed by extrusion) was used for construction of hydrophilic-USPIO encapsulating liposomes. Magnetoliposomes (ML) were characterized for size, surface charge, entrapment, physical stability and magnetic properties (relaxivity). Results show that nanosized extruded-DRV MLs encapsulate higher amounts of USPIOs in comparison with sonicated vesicles. Fe (III) encapsulation efficiency (EE) is 12%, the highest reported to date for nanosized MLs. EE of MLs is influenced by ML membrane composition and polyethyleneglycol (PEG) coating. PEG-coating increases ML EE and stability; however, r(2)-to-r(1) ratios decrease (in comparison with non-PEGylated MLs). Most ML-types are efficient T2 contrast agents (because r(2)-to-r(1) ratios are higher than that of free USPIOs). Targeted MLs were formed by successfully immobilizing OX-26 monoclonal antibody on ML surface (biotin-streptavidin ligation), without significant loss of USPIOs. Targeted MLs retained their nanosize and integrity during storage for 1 month at 4 °C and up to 2 weeks at 37 °C.

  7. Structural stability of methane hydrate at high pressures

    USGS Publications Warehouse

    Shu, J.; Chen, X.; Chou, I.-Ming; Yang, W.; Hu, Jiawen; Hemley, R.J.; Mao, Ho-kwang

    2011-01-01

    The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil cells. The diffraction data for types II (sII) and H (sH) were refined to the known structures with space groups Fd3m and P63/mmc, respectively. Upon compression, sI methane hydrate transforms to the sII phase at 120 MPa, and then to the sH phase at 600 MPa. The sII methane hydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methane hydrate decomposes at pressures above 3 GPa to form methane with the orientationally disordered Fm3m structure and ice VII (Pn3m). The results highlight the role of guest (CH4)-host (H2O) interactions in the stabilization of the hydrate structures under pressure. ?? 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

  8. A silica long base tiltmeter with high stability and resolution.

    PubMed

    Boudin, F; Bernard, P; Longuevergne, L; Florsch, N; Larmat, C; Courteille, C; Blum, P-A; Vincent, T; Kammentaler, M

    2008-03-01

    In order to be able to provide valuable data in multiparameter measurement field operations, tiltmeters need to have a noise level better or equal than 10(-9) rad for a period range from a few minutes to a few years and a long term stability ranging from 10(-7) to 10(-8) rad/yr. Tiltmeter measurements should also be as much as possible insensitive to thermal disturbances, by taking great care of the horizontality of the base line tube first. Secondly, thermal responses have been assessed. We also took great care of the coupling of our tiltmeters with the bedrock. We've designed a long base tiltmeter with sensors in silica which has a low dilatation coefficient. The linear variable displacement transducer is based on coil coupling (powered by an alternative voltage). Finally we show the results of two 100 m silica water tube tiltmeters which were installed in a mine in the French Vosges massif in the framework of a hydrology research project. These instruments show a remarkably good stability (6.5x10(-9) rad/month) and a low noise level (of the order of 10(-11) rad). Toroidal and spheroidal free modes of the Earth were observed after the two last major earthquakes on Sumatra.

  9. Structure Stability of Methane Hydrate at High Pressures

    SciTech Connect

    J Shu; X Chen; I Chou; W Yang; J Hu; R Hemley; K Mao

    2011-12-31

    The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil cells. The diffraction data for types II (sII) and H (sH) were refined to the known structures with space groups Fd3m and P6{sub 3}/mmc, respectively. Upon compression, sI methanehydrate transforms to the sII phase at 120 MPa, and then to the sH phase at 600 MPa. The sII methanehydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methanehydrate decomposes at pressures above 3 GPa to form methane with the orientationally disordered Fm3mstructure and ice VII (Pn3m). The results highlight the role of guest (CH{sub 4})-host (H{sub 2}O) interactions in the stabilization of the hydratestructures under pressure.

  10. Synthesis and stability of {alpha}-tricalcium phosphate doped with dicalcium silicate in the system Ca{sub 3}(PO{sub 4}){sub 2}-Ca{sub 2}SiO{sub 4}

    SciTech Connect

    Martinez, I.M.

    2010-07-15

    The aim of this study was to synthesize materials of {alpha}-tricalcium phosphate doped with small amounts of dicalcium silicate, by solid state reaction, at high temperature and slow cooling to room temperature. The obtained materials were characterized by X-ray diffraction, Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy, showing that there is a region between 0.5 and 4.0 wt.% of dicalcium silicate where solid solution {alpha}-tricalcium phosphate ({alpha}-TCPss) is stable to room temperature.

  11. Lyman alpha emitting galaxies at high redshift: Direct detection of young galaxies in a young universe

    NASA Astrophysics Data System (ADS)

    Dawson, Steven Arthur

    /DEIMOS follow-up observations to candidates selected in the Large Area Lyman Alpha (LALA) survey. We conclude that if there is evolution in the Lya luminosity function over these epochs, its significance is below the statistical uncertainty of these data. This result supports the conclusion from several smaller samples of high-redshift Lya---emitters that the intergalactic medium remains largely reionized from the local universe out to z [approximate] 6.5. However, it is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z ~ 3 and z ~ 6 in Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations. (Abstract shortened by UMI.)

  12. Construction of transforming growth factor alpha (TGF-alpha) phage library and identification of high binders of epidermal growth factor receptor (EGFR) by phage display.

    PubMed

    Tang, X B; Dallaire, P; Hoyt, D W; Sykes, B D; O'Connor-McCourt, M; Malcolm, B A

    1997-10-01

    TGF-alpha, a 50 amino acid growth factor containing 3 disulfide bonds, was fused to the N-terminal domain of the pIII protein of fusN, a derivative of phagemid fd-tet, to form a TGF-alpha phage. The fusion phage showed binding activity to epidermal growth factor receptor (EGFR). A library of approximately 4 x 10(7) variants of TGF-alpha was generated with substitutions of total of 10 amino acids located in the C-loop region. This C-loop subdomain of TGF-alpha consists of a small antiparallel double hairpin structure involving interactions between intra-polypeptide segments. Mutants isolated from the phage library with greatly increased binding affinity were selected through panning with A431 cells (a cell line expressing an elevated number of EGFRs). Following two rounds of stringent selection, variant phages with higher binding affinity than wild type TGF-alpha were identified and the phage DNAs were sequenced for the alignment analysis. Absolute selection at position 42 as Arg, preferential selection at position 38 and 45 as Tyr or Phe with aromatic side chain and selection at position 41 with acidic residues, were obtained. Although an amino acid residue with smaller side chain at position 35 and one with larger side chain at position 36 were preferred, the steric hindering of the structure in side chains was minimized between these adjacent amino acids.

  13. Deformation mechanisms for high-temperature creep of high yttria content stabilized zirconia single crystals

    SciTech Connect

    Gomez-Garcia, D.; Martinez-Fernandez, J.; Dominguez-Rodriguez, A.; Eveno, P.; Castaing, J.

    1996-03-01

    Creep of 21 mol.% yttria-stabilized zirconia single crystals has been studied between 1,400 and 1,800 C. The creep parameters have been determined indicating a change of the controlling mechanism around 1,500 C. At higher temperatures recovery creep is found to be the rate controlling mechanism, with a stress exponent {approx_equal} 3 and an activation energy {approx_equal} 6 eV. Transition to glide controlled creep occurs below 1,500 C, associated with larger stress exponents ({approx_equal} 5) and activation energies ({approx_equal} 8.5 eV). TEM observations of the dislocation microstructure confirm this transition. The influence of the high yttria content, which is at the origin of the high creep resistance of these crystals, is discussed for each range of temperatures.

  14. A new stability test for high-resolution palaeomagnetic data

    NASA Astrophysics Data System (ADS)

    Lurcock, Pontus; Florindo, Fabio

    2014-05-01

    Assessing the reliability of palaeomagnetic directions is a long-standing problem: how can it be determined that a set of measured palaeomagnetic directions truly records primary geomagnetic field directions, rather than being produced by one of the other processes which can affect rock magnetizations? One approach is to use rock magnetic analysis to establish that the rock should be capable of retaining a palaeofield direction. A complementary approach is the use of field tests of paleomagnetic stability, which analyse the palaeomagnetic directions themselves in the context of their position in the section or core. Perhaps the best known is the reversals test, which determines whether the mean direction computed from the normal-polarity sites is antiparallel to the mean direction for the reversed-polarity sites. Only a small number of stability tests have been devised, and none are universally applicable. We describe a new addition to this arsenal. Our proposed stability test, the secular continuity test, is applicable to data with sufficient temporal resolution to reflect geomagnetic secular variation. The secular variation of the geomagnetic field direction varies in a continuous manner, and statistical tests can be used to determine whether a sequence of measured directions is consistent with such behaviour. If a set of measured directions passes the continuity test, it indicates that they are reliable records of the geomagnetic field direction, since none of the other processes which impart remanence are known to vary in this way. A failed continuity test may merely indicate that the sampling interval was too large to capture variation at secular timescales. If, however, the sampling interval is known (from other constraints) to be short enough, a failed continuity test shows that the palaeomagnetic directions are unreliable due to unstable magnetizations, secondary overprints, or other confounding factors. The continuity test is implemented as a simple

  15. Determination of midazolam and its alpha-hydroxy metabolite in human plasma and urine by high-performance liquid chromatography.

    PubMed

    Ha, H R; Rentsch, K M; Kneer, J; Vonderschmitt, D J

    1993-08-01

    We describe a new high-performance liquid chromatography (HPLC) method for measurement of midazolam and its major metabolite, alpha-hydroxymidazolam, in clinical samples. Plasma or urine was mixed with 100 ng internal standard Ro 05-6669 and borate buffer, 0.1 M, pH 9. Midazolam and its related compounds were extracted into diethylether. The organic phase was evaporated to dryness. The residue was dissolved in HPLC mobile phase [methanol-isopropyl alcohol-perchloric acid, 0.5 microM (57:25:18)] and injected into the chromatograph. The separation of substances was performed on an Spherisorb S5CN 250 x 4.6 mm HPLC column maintained at 45 degrees C. The detection was performed by absorption measurement at 245 nm. At a flow rate of 1.7 ml/min, the retention times of Ro 05-6669, 1,4 dihydroxymidazolam, alpha-hydroxymidazolam, 4-hydroxymidazolam and midazolam were 4.0, 6.7, 7.8, 9.6, and 10.8 min, respectively. In the concentration range of 5-1,000 ng/ml, the calibration graphs for both compounds were linear. The coefficients of variation of the between-day and within-day assay were < 14% for the concentration range 5-10 and < 7% for the range 10-600 ng/ml. The limits of detection for midazolam and alpha-hydroxymidazolam were 2 and 4 ng/ml, respectively. This assay is more sensitive than earlier methods; it is simple and rapid, and it enables the quantification of midazolam and its alpha-hydroxy metabolite with very good precision and accuracy in human plasma and urine.

  16. Stability in high gain plasmas in DIII-D

    SciTech Connect

    Lazarus, E.A.; Houlberg, W.A.; Murakami, M.; Wade, M.R.

    1996-10-01

    Fusion power gain has been increased by a factor of 3 in DIII-D plasmas through the use of strong discharge shaping and tailoring of the pressure and current density profiles. H-mode plasmas with weak or negative central magnetic shear are found to have neoclassical ion confinement throughout most of the plasma volume. Improved MHD stability is achieved by controlling the plasma pressure profile width. The highest fusion power gain Q (ratio of fusion power to input power) in deuterium plasmas was 0.0015, which extrapolates to an equivalent Q of 0.32 in a deuterium-tritium plasma and is similar to values achieved in tokamaks of larger size and magnetic fields.

  17. Stability in High Gain Plasmas in DIII-D

    SciTech Connect

    Lazarus, E. A.; Hong, R. M.; Navratil, G. A.; Sabbagh, S.; Strait, E. J.; Rice, B. W.; Ferron, J. R.; Greenfield, C. M.; Austin, M. E.; Chan, V. S.; DeBoo, J. C.; Doyle, E. J.; Forest, C. B.; Leonard, A. W.; Schissel, D. P.; Whyte, D. G.

    1997-01-01

    Fusion power gain has been increased by a factor of 3 in DIII-D plasmas through the use of strong discharge shaping and tailoring of the pressure and current density profiles. H-mode plasmas with weak or negative central magnetic shear are found to have neoclassical ion confinement throughout most of the plasma volume. Improved MHD stability is achieved by controlling the plasma pressure profile width. The highest fusion power gain Q (ratio of fusion power to input power) in deuterium plasmas was 0.0015. which extrapolates to an equivalent Q of 0.32 in a deuterium-tritium plasma and is similar to values achieved in tokamaks of larger size and magnetic fields.

  18. Joule-Thomson cryogenic cooler with extremely high thermal stability

    NASA Technical Reports Server (NTRS)

    Bard, Steven; Wu, J. J.; Trimble, Curt

    1991-01-01

    An 80-K Joule-Thomson (J-T) cooling system designed for the Probe Infrared Laser Spectrometer (PIRLS) proposed for the Huygens Titan Probe of the Cassini Saturn orbiter mission is presented. The cryogenic cooling requirements of the PIRLS instrument are listed, and the cooler system design including details of a J-T cryostat, cold head, and dewar design is described along with the results of a thermal modeling effort and lab cooler performance testing. It is shown that by using active feedback temperature control of the cold head in combination with the self-regulating action of the J-T cryostat, a temperature stability of less than 0.1 mK/min is achieved by the cooler weighting 1.8 kg.

  19. Redesign of a Variable-Gain Output Feedback Longitudinal Controller Flown on the High-Alpha Research Vehicle (HARV)

    NASA Technical Reports Server (NTRS)

    Ostroff, Aaron J.

    1998-01-01

    This paper describes a redesigned longitudinal controller that flew on the High-Alpha Research Vehicle (HARV) during calendar years (CY) 1995 and 1996. Linear models are developed for both the modified controller and a baseline controller that was flown in CY 1994. The modified controller was developed with three gain sets for flight evaluation, and several linear analysis results are shown comparing the gain sets. A Neal-Smith flying qualities analysis shows that performance for the low- and medium-gain sets is near the level 1 boundary, depending upon the bandwidth assumed, whereas the high-gain set indicates a sensitivity problem. A newly developed high-alpha Bode envelope criterion indicates that the control system gains may be slightly high, even for the low-gain set. A large motion-base simulator in the United Kingdom was used to evaluate the various controllers. Desired performance, which appeared to be satisfactory for flight, was generally met with both the low- and medium-gain sets. Both the high-gain set and the baseline controller were very sensitive, and it was easy to generate pilot-induced oscillation (PIO) in some of the target-tracking maneuvers. Flight target-tracking results varied from level 1 to level 3 and from no sensitivity to PIO. These results were related to pilot technique and whether actuator rate saturation was encountered.

  20. High-Resolution {alpha} and Electron Spectroscopy of {sup 249}{sub 98}Cf

    SciTech Connect

    Ahmad, I.; Greene, J. P.; Kondev, F. G.; Zhu, S.

    2015-04-13

    alpha-particle spectra of Cf-249 have been measured with a double-focusing magnetic spectrometer and with passivated implanted planar silicon (PIPS) detectors. The conversion-electron spectra of Cf-249 have been measured with a cooled Si(Li) detector and with a room-temperature PIPS detector. Precise energies of a groups in the decay of Cf-249 have been measured with respect to the known energy of Cf-250. In addition, alpha-electron, alpha-gamma, and gamma-gamma coincidence measurements were also performed to determine the spin-parity of the previously known 643.64-keV level. From electron intensities, conversion coefficients of transitions in the daughter Cm-245 have been determined. The measured L-3 conversion coefficients of the 333.4- and 388.2-keV transitions are found to be in agreement with the theoretical conversion coefficients for pure E1 multipolarity. On the other hand, the K, L-1 + L-2, M, and N conversion coefficients are approximately twice the theoretical values for pure E1 transitions. These measurements indicate anomalous E1 conversion coefficients for the 333.4- and 388.2-keV transitions, as has been pointed out in earlier measurements. The measured conversion coefficient of the 255.5-keV transition gives an M1 multipolarity for this transition which establishes a spin-parity of 7/2(-) and the 7/2(-)[743] single-particle assignment to the 643.64-keV level.

  1. High spatial resolution photographs of the sun in L alpha radiation.

    NASA Technical Reports Server (NTRS)

    Prinz, D. K.

    1973-01-01

    Photographs of the sun in predominantly L alpha radiation (centered at 1215.67 A) with 3-sec spatial resolution were taken from an Aerobee rocket shortly after fourth contact by the moon on the eclipse day of July 10, 1972. This preliminary reporting of the results describes the instrument and shows two of the photographs taken. The supergranulation is manifest, and active regions and filaments are well resolved over the entire disk. Densitometer traces across the disk are presented, giving the flux incident on the earth from active regions, cell boundaries, and filaments.

  2. Highly Potent, Water Soluble Benzimidazole Antagonist for Activated (alpha)4(beta)1 Integrin

    SciTech Connect

    Carpenter, R D; Andrei, M; Lau, E Y; Lightstone, F C; Liu, R; Lam, K S; Kurth, M J

    2007-08-29

    The cell surface receptor {alpha}{sub 4}{beta}{sub 1} integrin, activated constitutively in lymphoma, can be targeted with the bisaryl urea peptidomimetic antagonist 1 (LLP2A). However, concerns on its preliminary pharmacokinetic (PK) profile provided an impetus to change the pharmacophore from a bisaryl urea to a 2-arylaminobenzimidazole moiety resulting in improved solubility while maintaining picomolar potency [5 (KLCA4); IC{sub 50} = 305 pM]. With exceptional solubility, this finding has potential for improving PK to help diagnose and treat lymphomas.

  3. High Serum Interleukin-10 and Tumor Necrosis Factor Alpha Levels in Chronic Paracoccidioidomycosis

    PubMed Central

    Fornari, M. C.; Bava, A. J.; Guereño, M. T.; Berardi, V. E.; Silaf, M. R.; Negroni, R.; Diez, R. A.

    2001-01-01

    In patients with chronic paracoccidioidomycosis (n = 10), levels of tumor necrosis factor alpha, interleukin-10, and interleukin-2 in serum, measured by enzyme-linked immunosorbent assay (in picograms per milliliter, as mean ± standard error of the mean), were higher than in normal controls (n = 8): 186 ± 40 versus 40 ± 7 (P < 0.05), 203 ± 95 versus 20 ± 8 (P = 0.001), and 96.3 ± 78.57 versus 1.19 ± 1.19 (P = 0.045), respectively. Gamma interferon and interleukin-4 levels were similar in patients and controls. PMID:11527826

  4. 1,5-asymmetric induction of chirality using pi-allyltricarbonyliron lactone complexes: highly diastereoselective synthesis of alpha-functionalised carbonyl compounds.

    PubMed

    Hollowood, Christopher J; Ley, Steven V; Wright, Edward A

    2003-09-21

    Silyl enol ethers derived from ketone functionalised rho-allyltricarbonyliron lactone complexes undergo highly diastereoselective carbon-fluorine and carbon-oxygen bond formation reactions with excellent control at the alpha-stereogenic centre.

  5. Stabilization and highly metallic properties of heavy group-V hydrides at high pressures

    NASA Astrophysics Data System (ADS)

    Abe, Kazutaka; Ashcroft, N. W.

    2015-12-01

    Compressed hydrides of the heavy group-15 elements Bi and Sb are investigated using ab initio methods. While the hydrides of Bi and Sb are known to be quite unstable at one atmosphere, our calculations predict that they can be stabilized at high pressures. Thus, at the composition of XH 3 (X =Bi or Sb), possible Bi hydrides are BiH2(P n m a ) + H beyond 105 GPa and BiH3(I 41/a m d ) beyond 250 GPa; for Sb hydrides, SbH2 + H hardly appears, and SbH3(P n m a ) is stabilized beyond 150 GPa. All of these hydrides are metallic with very dispersive electronic structures, this being in accordance with the predictions of the Goldhammer-Herzfeld criterion. Superconducting transition temperatures have also been estimated from the extended McMillan equation, and they turn out to be 39 K for BiH2 at 125 GPa, 65 K for BiH3 at 270 GPa, and 68 K for SbH3 at 170 GPa.

  6. Chaperone-like activities of {alpha}-synuclein: {alpha}-Synuclein assists enzyme activities of esterases

    SciTech Connect

    Ahn, Misun; Kim, SeungBum; Kang, Mira; Ryu, Yeonwoo . E-mail: ywryu@ajou.ac.kr; Doohun Kim, T. . E-mail: doohunkim@ajou.ac.kr

    2006-08-11

    {alpha}-Synuclein, a major constituent of Lewy bodies (LBs), has been implicated to play a critical role in the pathogenesis of Parkinson's disease (PD), although the physiological function of {alpha}-synuclein has not yet been known. Here we have shown that {alpha}-synuclein, which has no well-defined secondary or tertiary structure, can protect the enzyme activity of microbial esterases against stress conditions such as heat, pH, and organic solvents. In particular, the flexibility of {alpha}-synuclein and its C-terminal region seems to be important for complex formation, but the structural integrity of the C-terminal region may not be required for stabilization of enzyme activity. In addition, atomic force microscopy (AFM) and in vivo enzyme assays showed highly specific interactions of esterases with {alpha}-synuclein. Our results indicate that {alpha}-synuclein not only protects the enzyme activity of microbial esterases in vitro, but also can stabilize the active conformation of microbial esterases in vivo.

  7. Characterization of the denatured structure of pyrrolidone carboxyl peptidase from a hyperthermophile under nondenaturing conditions: role of the C-terminal alpha-helix of the protein in folding and stability.

    PubMed

    Iimura, Satoshi; Umezaki, Taro; Takeuchi, Makoto; Mizuguchi, Mineyuki; Yagi, Hiromasa; Ogasahara, Kyoko; Akutsu, Hideo; Noda, Yasuo; Segawa, Shin-ichi; Yutani, Katsuhide

    2007-03-27

    The cysteine-free pyrrolidone carboxyl peptidase (PCP-0SH) from a hyperthermophile, Pyrococcus furiosus, can be trapped in the denatured state under nondenaturing conditions, corresponding to the denatured structure that exists in equilibrium with the native state under physiological conditions. The denatured state is the initial state (D1 state) in the refolding process but differs from the completely denatured state (D2 state) in the concentrated denaturant. Also, it has been found that the D1 state corresponds to the heat-denatured state. To elucidate the structural basis of the D1 state, H/D exchange experiments with PCP-0SH were performed at pD 3.4 and 4 degrees C. The results indicated that amide protons in the C-terminal alpha6-helix region hardly exchanged in the D1 state with deuterium even after 7 days, suggesting that the alpha6-helix (from Ser188 to Glu205) of PCP-0SH was stably formed in the D1 state. In order to examine the role of the alpha6-helix in folding and stability, H/D exchange experiments with a mutant, A199P, at position 199 in the alpha6-helix region were performed. The alpha6-helix region of A199P in the D1 state was partially unprotected, while some hydrophobic residues were protected against the H/D exchange, although these hydrophobic residues were unprotected in the wild-type protein. These results suggest that the structure of A199P in the D1 state formed a temporary stable denatured structure with a non-native hydrophobic cluster and the unstructured alpha6-helix. Both the stability and the refolding rate decreased by the substitution of Pro for Ala199. We can conclude that the native-like helix (alpha6-helix) of PCP-0SH is already constructed in the D1 state and is necessary for efficient refolding into the native structure and stabilization of PCP-0SH.

  8. Role of the two catalytic domains of DSR-E dextransucrase and their involvement in the formation of highly alpha-1,2 branched dextran.

    PubMed

    Fabre, Emeline; Bozonnet, Sophie; Arcache, Audrey; Willemot, René-Marc; Vignon, Michel; Monsan, Pierre; Remaud-Simeon, Magali

    2005-01-01

    The dsrE gene from Leuconostoc mesenteroides NRRL B-1299 was shown to encode a very large protein with two potentially active catalytic domains (CD1 and CD2) separated by a glucan binding domain (GBD). From sequence analysis, DSR-E was classified in glucoside hydrolase family 70, where it is the only enzyme to have two catalytic domains. The recombinant protein DSR-E synthesizes both alpha-1,6 and alpha-1,2 glucosidic linkages in transglucosylation reactions using sucrose as the donor and maltose as the acceptor. To investigate the specific roles of CD1 and CD2 in the catalytic mechanism, truncated forms of dsrE were cloned and expressed in Escherichia coli. Gene products were then small-scale purified to isolate the various corresponding enzymes. Dextran and oligosaccharide syntheses were performed. Structural characterization by (13)C nuclear magnetic resonance and/or high-performance liquid chromatography showed that enzymes devoid of CD2 synthesized products containing only alpha-1,6 linkages. On the other hand, enzymes devoid of CD1 modified alpha-1,6 linear oligosaccharides and dextran acceptors through the formation of alpha-1,2 linkages. Therefore, each domain is highly regiospecific, CD1 being specific for the synthesis of alpha-1,6 glucosidic bonds and CD2 only catalyzing the formation of alpha-1,2 linkages. This finding permitted us to elucidate the mechanism of alpha-1,2 branching formation and to engineer a novel transglucosidase specific for the formation of alpha-1,2 linkages. This enzyme will be very useful to control the rate of alpha-1,2 linkage synthesis in dextran or oligosaccharide production.

  9. Structure-function validation of high lysine analogs of alpha-hordothionin designed by protein modeling.

    PubMed

    Rao, A G; Hassan, M; Hempel, J C

    1994-12-01

    Cereal grains and legume seeds, which are key protein sources for the vegetarian diet, are generally deficient in essential amino acids. Maize, in particular, is deficient in lysine. The inherent lack of lysine-rich proteins in maize has necessitated the search for heterologous proteins enriched in this amino acid, the isolation of the corresponding gene and its ultimate introduction into maize through plant transformation techniques. However, a rate-limiting step to this strategy has been the availability of plant-derived lysine-rich proteins. An appealing solution to the problem is to artificially increase the lysine content of a given protein by mutating appropriate residues to lysine. Here, we expound this strategy, starting with the protein alpha-hordothionin that is derived from barley seeds and consists of five lysine residues in a total of 45 amino acids (11% lysine). To facilitate rational substitutions, the 3-D structure of the protein has been determined by homology modeling with crambin. Based on this model, we have identified surface residues amenable to substitution with lysine. Furthermore, the acceptability of the mutations has been validated through the synthesis and characterization of the derivatives. To this end, our approach has permitted the creation of a modified alpha-hordothionin protein that has a lysine content of approximately 27% and retains the antifungal activity of the wild-type protein.

  10. Constitutive stabilization of hypoxia-inducible factor alpha selectively promotes the self-renewal of mesenchymal progenitors and maintains mesenchymal stromal cells in an undifferentiated state.

    PubMed

    Park, In-Ho; Kim, Kwang-Ho; Choi, Hyun-Kyung; Shim, Jae-Seung; Whang, Soo-Young; Hahn, Sang June; Kwon, Oh-Joo; Oh, Il-Hoan

    2013-09-27

    With the increasing use of culture-expanded mesenchymal stromal cells (MSCs) for cell therapies, factors that regulate the cellular characteristics of MSCs have been of major interest. Oxygen concentration has been shown to influence the functions of MSCs, as well as other normal and malignant stem cells. However, the underlying mechanisms of hypoxic responses and the precise role of hypoxia-inducible factor-1α (Hif-1α), the master regulatory protein of hypoxia, in MSCs remain unclear, due to the limited span of Hif-1α stabilization and the complex network of hypoxic responses. In this study, to further define the significance of Hif-1α in MSC function during their self-renewal and terminal differentiation, we established adult bone marrow (BM)-derived MSCs that are able to sustain high level expression of ubiquitin-resistant Hif-1α during such long-term biological processes. Using this model, we show that the stabilization of Hif-1α proteins exerts a selective influence on colony-forming mesenchymal progenitors promoting their self-renewal and proliferation, without affecting the proliferation of the MSC mass population. Moreover, Hif-1α stabilization in MSCs led to the induction of pluripotent genes (oct-4 and klf-4) and the inhibition of their terminal differentiation into osteogenic and adipogenic lineages. These results provide insights into the previously unrecognized roles of Hif-1α proteins in maintaining the primitive state of primary MSCs and on the cellular heterogeneities in hypoxic responses among MSC populations.

  11. Stability of numerous novel potassium chlorides at high pressure

    NASA Astrophysics Data System (ADS)

    Zhang, Weiwei; Oganov, Artem R.; Zhu, Qiang; Lobanov, Sergey S.; Stavrou, Elissaios; Goncharov, Alexander F.

    2016-05-01

    K-Cl is a simple system displaying all four main types of bonding, as it contains (i) metallic potassium, (ii) elemental chlorine made of covalently bonded Cl2 molecules held together by van der Waals forces, and (iii) an archetypal ionic compound KCl. The charge balance rule, assigning classical charges of “+1” to K and “‑1” to Cl, predicts that no compounds other than KCl are possible. However, our quantum-mechanical variable-composition evolutionary simulations predict an extremely complex phase diagram, with new thermodynamically stable compounds K3Cl, K2Cl, K3Cl2, K4Cl3, K5Cl4, K3Cl5, KCl3 and KCl7. Of particular interest are 2D-metallic homologs Kn+1Cln, the presence of positively charged Cl atoms in KCl7, and the predicted stability of KCl3 already at nearly ambient pressures at zero Kelvin. We have synthesized cubic -KCl3 at 40–70 GPa and trigonal -KCl3 at 20–40 GPa in a laser-heated diamond anvil cell (DAC) at temperature exceeding 2000 K from KCl and Cl2. These phases were identified using in situ synchrotron X-ray diffraction and Raman spectroscopy. Upon unloading to 10 GPa, -KCl3 transforms to a yet unknown structure before final decomposition to KCl and Cl2 at near-ambient conditions.

  12. High Conformational Stability of Secreted Eukaryotic Catalase-peroxidases

    PubMed Central

    Zámocký, Marcel; García-Fernández, Queralt; Gasselhuber, Bernhard; Jakopitsch, Christa; Furtmüller, Paul G.; Loewen, Peter C.; Fita, Ignacio; Obinger, Christian; Carpena, Xavi

    2012-01-01

    Catalase-peroxidases (KatGs) are bifunctional heme enzymes widely spread in archaea, bacteria, and lower eukaryotes. Here we present the first crystal structure (1.55 Å resolution) of an eukaryotic KatG, the extracellular or secreted enzyme from the phytopathogenic fungus Magnaporthe grisea. The heme cavity of the homodimeric enzyme is similar to prokaryotic KatGs including the unique distal +Met-Tyr-Trp adduct (where the Trp is further modified by peroxidation) and its associated mobile arginine. The structure also revealed several conspicuous peculiarities that are fully conserved in all secreted eukaryotic KatGs. Peculiarities include the wrapping at the dimer interface of the N-terminal elongations from the two subunits and cysteine residues that cross-link the two subunits. Differential scanning calorimetry and temperature- and urea-mediated unfolding followed by UV-visible, circular dichroism, and fluorescence spectroscopy combined with site-directed mutagenesis demonstrated that secreted eukaryotic KatGs have a significantly higher conformational stability as well as a different unfolding pattern when compared with intracellular eukaryotic and prokaryotic catalase-peroxidases. We discuss these properties with respect to the structure as well as the postulated roles of this metalloenzyme in host-pathogen interactions. PMID:22822072

  13. Stability of numerous novel potassium chlorides at high pressure

    PubMed Central

    Zhang, Weiwei; Oganov, Artem R.; Zhu, Qiang; Lobanov, Sergey S.; Stavrou, Elissaios; Goncharov, Alexander F.

    2016-01-01

    K-Cl is a simple system displaying all four main types of bonding, as it contains (i) metallic potassium, (ii) elemental chlorine made of covalently bonded Cl2 molecules held together by van der Waals forces, and (iii) an archetypal ionic compound KCl. The charge balance rule, assigning classical charges of “+1” to K and “−1” to Cl, predicts that no compounds other than KCl are possible. However, our quantum-mechanical variable-composition evolutionary simulations predict an extremely complex phase diagram, with new thermodynamically stable compounds K3Cl, K2Cl, K3Cl2, K4Cl3, K5Cl4, K3Cl5, KCl3 and KCl7. Of particular interest are 2D-metallic homologs Kn+1Cln, the presence of positively charged Cl atoms in KCl7, and the predicted stability of KCl3 already at nearly ambient pressures at zero Kelvin. We have synthesized cubic -KCl3 at 40–70 GPa and trigonal -KCl3 at 20–40 GPa in a laser-heated diamond anvil cell (DAC) at temperature exceeding 2000 K from KCl and Cl2. These phases were identified using in situ synchrotron X-ray diffraction and Raman spectroscopy. Upon unloading to 10 GPa, -KCl3 transforms to a yet unknown structure before final decomposition to KCl and Cl2 at near-ambient conditions. PMID:27211847

  14. Stability of coronene at high temperature and pressure.

    PubMed

    Jennings, E; Montgomery, W; Lerch, Ph

    2010-12-09

    The infrared response of coronene (C(24)H(12)) under pressure and temperature conditions up to 10 GPa and 300 °C is examined in situ using a diamond anvil cell and synchrotron-source Fourier transform infrared (FTIR) spectroscopy. Coronene is a polycyclic aromatic hydrocarbon that is present in the interstellar medium and meteorites which may have contributed to the Earth's primordial carbon budget. It appears to undergo a reversible phase transition between 2 and 3.2 GPa at ambient temperature; new intramolecular bonds in the region 840-880 cm(-1) result from compression. We document the shift of spectral features to higher wavenumbers with increasing pressure but find this change suppressed by increased temperature. By investigating the stability of coronene over a range of naturally occurring conditions found in a range of environments, we assess the survival of the molecule through various terrestrial and extraterrestrial processes. Coronene has previously been shown to survive atmospheric entry during Earth accretion; this can now be extended to include survival through geological processes such as subduction and silicate melting of the rock cycle, opening the possibility of extraterrestrial coronene predating terrestrial accretion existing on Earth.

  15. Highly polarized emission in spin resolved photoelectron spectroscopy of alpha-Fe(001)/GaAs(001)

    SciTech Connect

    Tobin, James; Yu, Sung Woo; Morton, Simon; Waddill, George; Thompson, Jamie; Neal, James; Spangenberg, Matthais; Shen, T.H.

    2009-05-19

    Highly spin-polarized sources of electrons, Integrated into device design, remain of great interest to the spintronic and magneto-electronic device community Here, the growth of Fe upon GaAs(001) has been studied with photoelectron spectroscopy (PES), including Spin Resolved PES. Despite evidence of atomic level disorder such as intermixing, an over-layer with the spectroscopic signature of alpha-Fe(001), with a bcc real space ordering, Is obtained The results will be discussed in light of the possibility of using such films as a spin-polarized source in device applications.

  16. Parameter Identification Flight Test Maneuvers for Closed Loop Modeling of the F-18 High Alpha Research Vehicle (HARV)

    NASA Technical Reports Server (NTRS)

    Batterson, James G. (Technical Monitor); Morelli, E. A.

    1996-01-01

    Flight test maneuvers are specified for the F-18 High Alpha Research Vehicle (HARV). The maneuvers were designed for closed loop parameter identification purposes, specifically for longitudinal and lateral linear model parameter estimation at 5,20,30,45, and 60 degrees angle of attack, using the Actuated Nose Strakes for Enhanced Rolling (ANSER) control law in Thrust Vectoring (TV) mode. Each maneuver is to be realized by applying square wave inputs to specific pilot station controls using the On-Board Excitation System (OBES). Maneuver descriptions and complete specifications of the time / amplitude points defining each input are included, along with plots of the input time histories.

  17. Piloted Parameter Identification Flight Test Maneuvers for Closed Loop Modeling of the F-18 High Alpha Research Vehicle (HARV)

    NASA Technical Reports Server (NTRS)

    Morelli, Eugene A.

    1996-01-01

    Flight test maneuvers are specified for the F-18 High Alpha Research Vehicle (HARV). The maneuvers were designed for closed loop parameter identification purposes, specifically for longitudinal and lateral linear model parameter estimation at 5, 20, 30, 45, and 60 degrees angle of attack, using the NASA 1A control law. Each maneuver is to be realized by the pilot applying square wave inputs to specific pilot station controls. Maneuver descriptions and complete specifications of the time/amplitude points defining each input are included, along with plots of the input time histories.

  18. Oxidation products of alpha-pinene: stabilized Criegee Intermediates and Extremely Low Volatility Organic Compounds in the CLOUD chamber and the boreal forest

    NASA Astrophysics Data System (ADS)

    Sarnela, Nina; Sipilä, Mikko; Ehn, Mikael; Rissanen, Matti P.; Jokinen, Tuija; Petäjä, Tuukka; Kulmala, Markku

    2015-04-01

    Atmospheric oxidation is an important phenomenon enhancing atmospheric aerosol particle formation as more oxidized compounds generally condense more readily due to their lower vapour pressure. By now, especially two oxidation processes have been identified as relevant for new particle formation: the oxidation of sulphur dioxide to sulphuric acid and oxidation of volatile organic compounds to extremely low volatility organic compounds (ELVOC, Ehn et al. 2014). The most significant atmospheric oxidants have been thought to be ozone, the hydroxyl radical and the nitrate radical but recently the importance of stabilized Criegee Intermediates (sCI) in atmospheric oxidation has been brought into discussion (Mauldin et al. 2012, Boy et al. 2013). The formation mechanisms of ELVOCs and the oxidation of sulphur dioxide by sCIs, have been investigated in recent laboratory studies (Sipilä et al. 2014, Ehn et al. 2014). In this study we explore the validity of those mechanisms in chamber and field measurements. The sCI, ELVOC and sulphuric acid concentrations were measured by a chemical ionization atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometer. The ozonolysis of alpha-pinene, the most abundant monoterpene in the boreal forest, was studied in measurements in the CLOUD-chamber in CERN and the ELVOC and sulphuric acid concentrations were compared with calculated yields of oxidation products. The ambient concentrations of sCI and ELVOC were measured at boreal forest site (Hyytiälä, Finland) and compared to corresponding calculated proxies. Both ambient and chamber measurements were found to be in good agreement with the calculated concentrations. More detailed discussion of the results will be presented in the conference. Boy, M., Mogensen, D., Smolander, S., Zhou, L., Nieminen, T., Paasonen, P., Plass-Dülmer, C., Sipilä, M., Petäjä, T., Mauldin, L., Berresheim H. and Kulmala M. (2013). Oxidation of SO2 by stabilized Criegee intermediate (s

  19. Stability of numerous novel potassium chlorides at high pressure

    DOE PAGES

    Zhang, Weiwei; Oganov, Artem R.; Lobanov, Sergey S.; ...

    2016-05-23

    K-Cl is a simple system displaying all four main types of bonding, as it contains (i) metallic potassium, (ii) elemental chlorine made of covalently bonded Cl2 molecules held together by van der Waals forces, and (iii) an archetypal ionic compound KCl. The charge balance rule, assigning classical charges of “+1” to K and “–1” to Cl, predicts that no compounds other than KCl are possible. However, our quantum-mechanical variable-composition evolutionary simulations predict an extremely complex phase diagram, with new thermodynamically stable compounds K3Cl, K2Cl, K3Cl2, K4Cl3, K5Cl4, K3Cl5, KCl3 and KCl7. Of particular interest are 2D-metallic homologs Kn+1Cln, the presencemore » of positively charged Cl atoms in KCl7, and the predicted stability of KCl3 already at nearly ambient pressures at zero Kelvin. We have synthesized cubic Pm3¯n -KCl3 at 40–70 GPa and trigonal P3¯cl -KCl3 at 20–40 GPa in a laser-heated diamond anvil cell (DAC) at temperature exceeding 2000 K from KCl and Cl2. These phases were identified using in situ synchrotron X-ray diffraction and Raman spectroscopy. Lastly, upon unloading to 10 GPa, P3¯cl -KCl3 transforms to a yet unknown structure before final decomposition to KCl and Cl2 at near-ambient conditions.« less

  20. Stability of numerous novel potassium chlorides at high pressure

    SciTech Connect

    Zhang, Weiwei; Oganov, Artem R.; Lobanov, Sergey S.; Stavrou, Elissaios; Goncharov, Alexander F.; Zhu, Qiang

    2016-05-23

    K-Cl is a simple system displaying all four main types of bonding, as it contains (i) metallic potassium, (ii) elemental chlorine made of covalently bonded Cl2 molecules held together by van der Waals forces, and (iii) an archetypal ionic compound KCl. The charge balance rule, assigning classical charges of “+1” to K and “–1” to Cl, predicts that no compounds other than KCl are possible. However, our quantum-mechanical variable-composition evolutionary simulations predict an extremely complex phase diagram, with new thermodynamically stable compounds K3Cl, K2Cl, K3Cl2, K4Cl3, K5Cl4, K3Cl5, KCl3 and KCl7. Of particular interest are 2D-metallic homologs Kn+1Cln, the presence of positively charged Cl atoms in KCl7, and the predicted stability of KCl3 already at nearly ambient pressures at zero Kelvin. We have synthesized cubic Pm3¯n -KCl3 at 40–70 GPa and trigonal P3¯cl -KCl3 at 20–40 GPa in a laser-heated diamond anvil cell (DAC) at temperature exceeding 2000 K from KCl and Cl2. These phases were identified using in situ synchrotron X-ray diffraction and Raman spectroscopy. Lastly, upon unloading to 10 GPa, P3¯cl -KCl3 transforms to a yet unknown structure before final decomposition to KCl and Cl2 at near-ambient conditions.

  1. Highly conserved tyrosine stabilizes the active state of rhodopsin.

    PubMed

    Goncalves, Joseph A; South, Kieron; Ahuja, Shivani; Zaitseva, Ekaterina; Opefi, Chikwado A; Eilers, Markus; Vogel, Reiner; Reeves, Philip J; Smith, Steven O

    2010-11-16

    Light-induced isomerization of the 11-cis-retinal chromophore in the visual pigment rhodopsin triggers displacement of the second extracellular loop (EL2) and motion of transmembrane helices H5, H6, and H7 leading to the active intermediate metarhodopsin II (Meta II). We describe solid-state NMR measurements of rhodopsin and Meta II that target the molecular contacts in the region of the ionic lock involving these three helices. We show that a contact between Arg135(3.50) and Met257(6.40) forms in Meta II, consistent with the outward rotation of H6 and breaking of the dark-state Glu134(3.49)-Arg135(3.50)-Glu247(6.30) ionic lock. We also show that Tyr223(5.58) and Tyr306(7.53) form molecular contacts with Met257(6.40). Together these results reveal that the crystal structure of opsin in the region of the ionic lock reflects the active state of the receptor. We further demonstrate that Tyr223(5.58) and Ala132(3.47) in Meta II stabilize helix H5 in an active orientation. Mutation of Tyr223(5.58) to phenylalanine or mutation of Ala132(3.47) to leucine decreases the lifetime of the Meta II intermediate. Furthermore, the Y223F mutation is coupled to structural changes in EL2. In contrast, mutation of Tyr306(7.53) to phenylalanine shows only a moderate influence on the Meta II lifetime and is not coupled to EL2.

  2. Use of Source Term and Air Dispersion Modeling in Planning Demolition of Highly Alpha-Contaminated Buildings

    SciTech Connect

    Droppo, James G.; Napier, Bruce A.; Rishel, Jeremy P.; Bloom, Richard W.

    2011-06-22

    The current cleanup of structures related to cold-war production of nuclear materials includes the need to demolish a number of highly alpha-contaminated structures. The process of planning for the demolition of such structures includes unique challenges related to ensuring the protection of both workers and the public. Pre-demolition modeling analyses were conducted to evaluate potential exposures resulting from the proposed demolition of a number of these structures. Estimated emission rates of transuranic materials during demolition are used as input to an air-dispersion model. The climatological frequencies of occurrence of peak air and surface exposures at locations of interest are estimated based on years of hourly meteorological records. The modeling results indicate that downwind deposition is the main operational limitation for demolition of a highly alpha-contaminated building. The pre-demolition modeling directed the need for better contamination characterization and/or different demolition methods—and in the end, provided a basis for proceeding with the planned demolition activities. Post-demolition modeling was also conducted for several contaminated structures, based on the actual demolition schedule and conditions. Comparisons of modeled and monitoring results are shown. Recent monitoring data from the demolition of a UO3 plant shows increments in concentrations that were previously identified in the pre-demolition modeling predictions; these comparisons confirm the validity and value of the pre-demolition source-term and air dispersion computations for planning demolition activities for other buildings with high levels of radioactive contamination.

  3. Mivazerol, a novel compound with high specificity for alpha 2 adrenergic receptors: binding studies on different human and rat membrane preparations.

    PubMed

    Noyer, M; de Laveleye, F; Vauquelin, G; Gobert, J; Wülfert, E

    1994-03-01

    Mivazerol, 3-[1(H-imidazol-4-yl)methyl]-2-hydroxybenzamide hydrochloride, a new potential anti-ischemic drug designed by UCB S.A. Pharma Sector, has been studied in binding experiments on adrenergic, dopaminergic, serotoninergic, muscarinic and idazoxan binding sites. Our results indicate that this compound displays high affinity and marked specificity for alpha 2 adrenoceptors. Mivazerol displaced the binding of the alpha 2 adrenoceptor antagonist [3H]RX 821002 to the alpha 2A adrenoceptors in human frontal cortex membranes with an apparent Ki value of 37 nM. The competition curve was shallow (nH = 0.55), suggesting that this compound acts as an alpha 2 adrenergic agonist. Mivazerol was also a potent competitor for [3H]RX 821002 binding to human platelet membranes (containing alpha 2A adrenoceptors) and rat kidney membranes (75% of the alpha 2 adrenoceptors of the alpha 2B subtype), indicating that this compound is not alpha 2 adrenoceptor subtype selective. Equilibrium dissociation constants for alpha 1 adrenoceptors (displacement of [3H]prazosin) and 5-HT1A receptors (displacement of [3H]rauwolscine) were respectively about 120 times (Ki = 4.4 microM) and 14 times (Ki = 530 nM) higher than that for the alpha 2 adrenoceptors. Equilibrium dissociation constants were approximately 1000 times higher for all other receptors tested in this study; namely beta 1 and beta 2 adrenoceptors, D1- and D2-dopamine receptors, M1-, M2- and M3-muscarinic receptors, 5-HT2 receptors and non-adrenergic idazoxan binding sites.

  4. Formation and stability of high-spin alkali clusters.

    PubMed

    Schulz, C P; Claas, P; Schumacher, D; Stienkemeier, F

    2004-01-09

    Helium nanodroplet isolation has been applied to agglomerate alkali clusters at temperatures of 380 mK. The very weak binding to the surface of the droplets allows a selection of only weakly bound, high-spin states. Here we show that larger clusters of alkali atoms in high-spin states can be formed. The lack of strong bonds from pairing electrons makes these systems nonmetallic, van der Waals-like complexes of metal atoms. We find that sodium and potassium readily form such clusters containing up to 25 atoms. In contrast, this process is suppressed for rubidium and cesium. Apparently, for these heavy alkalis, larger high-spin aggregates are not stable and depolarize spontaneously upon cluster formation.

  5. Formation and Stability of High-Spin Alkali Clusters

    NASA Astrophysics Data System (ADS)

    Schulz, C. P.; Claas, P.; Schumacher, D.; Stienkemeier, F.

    2004-01-01

    Helium nanodroplet isolation has been applied to agglomerate alkali clusters at temperatures of 380mK. The very weak binding to the surface of the droplets allows a selection of only weakly bound, high-spin states. Here we show that larger clusters of alkali atoms in high-spin states can be formed. The lack of strong bonds from pairing electrons makes these systems nonmetallic, vanderWaals like complexes of metal atoms. We find that sodium and potassium readily form such clusters containing up to 25atoms. In contrast, this process is suppressed for rubidium and cesium. Apparently, for these heavy alkalis, larger high-spin aggregates are not stable and depolarize spontaneously upon cluster formation.

  6. Atomic frequency standards for ultra-high-frequency stability

    NASA Technical Reports Server (NTRS)

    Maleki, L.; Prestage, J. D.; Dick, G. J.

    1987-01-01

    The general features of the Hg-199(+) trapped-ion frequency standard are outlined and compared to other atomic frequency standards, especially the hydrogen maser. The points discussed are those which make the trapped Hg-199(+) standard attractive: high line Q, reduced sensitivity to external magnetic fields, and simplicity of state selection, among others.

  7. Preparations for flight research to evaluate actuated forebody strakes on the F-18 high-alpha research vehicle

    NASA Technical Reports Server (NTRS)

    Murri, Daniel G.; Shah, Gautam H.; Dicarlo, Daniel J.

    1994-01-01

    As part of the NASA High-Angle-of-Attack Technology Program (HATP), flight tests are currently being conducted with a multi-axis thrust vectoring system applied to the NASA F-18 High Alpha Research Vehicle (HARV). A follow-on series of flight tests with the NASA F-18 HARV will be focusing on the application of actuated forebody strake controls. These controls are designed to provide increased levels of yaw control at high angles of attack where conventional aerodynamic controls become ineffective. The series of flight tests are collectively referred to as the Actuated Nose Strakes for Enhanced Rolling (ANSER) Flight Experiment. The development of actuated forebody strake controls for the F-18 HARV is discussed and a summary of the ground tests conducted in support of the flight experiment is provided. A summary of the preparations for the flight tests is also provided.

  8. Unexpected high digestion rate of cooked starch by the Ct-Maltase-Glucoamylase small intestine mucosal alpha-glucosidase subunit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For starch digestion to glucose, two luminal alpha-amylases and four gut mucosal alpha-glucosidase subunits are employed. The aim of this research was to investigate, for the first time, direct digestion capability of individual mucosal alpha-glucosidases on cooked (gelatinized) starch. Gelatinized ...

  9. Protein linear indices of the 'macromolecular pseudograph alpha-carbon atom adjacency matrix' in bioinformatics. Part 1: prediction of protein stability effects of a complete set of alanine substitutions in Arc repressor.

    PubMed

    Marrero-Ponce, Yovani; Medina-Marrero, Ricardo; Castillo-Garit, Juan A; Romero-Zaldivar, Vicente; Torrens, Francisco; Castro, Eduardo A

    2005-04-15

    A novel approach to bio-macromolecular design from a linear algebra point of view is introduced. A protein's total (whole protein) and local (one or more amino acid) linear indices are a new set of bio-macromolecular descriptors of relevance to protein QSAR/QSPR studies. These amino-acid level biochemical descriptors are based on the calculation of linear maps on Rn[f k(xmi):Rn-->Rn] in canonical basis. These bio-macromolecular indices are calculated from the kth power of the macromolecular pseudograph alpha-carbon atom adjacency matrix. Total linear indices are linear functional on Rn. That is, the kth total linear indices are linear maps from Rn to the scalar R[f k(xm):Rn-->R]. Thus, the kth total linear indices are calculated by summing the amino-acid linear indices of all amino acids in the protein molecule. A study of the protein stability effects for a complete set of alanine substitutions in the Arc repressor illustrates this approach. A quantitative model that discriminates near wild-type stability alanine mutants from the reduced-stability ones in a training series was obtained. This model permitted the correct classification of 97.56% (40/41) and 91.67% (11/12) of proteins in the training and test set, respectively. It shows a high Matthews correlation coefficient (MCC=0.952) for the training set and an MCC=0.837 for the external prediction set. Additionally, canonical regression analysis corroborated the statistical quality of the classification model (Rcanc=0.824). This analysis was also used to compute biological stability canonical scores for each Arc alanine mutant. On the other hand, the linear piecewise regression model compared favorably with respect to the linear regression one on predicting the melting temperature (tm) of the Arc alanine mutants. The linear model explains almost 81% of the variance of the experimental tm (R=0.90 and s=4.29) and the LOO press statistics evidenced its predictive ability (q2=0.72 and scv=4.79). Moreover, the

  10. Simultaneous determination of retinol, alpha-tocopherol, and 25-hydroxyvitamin D in human serum by high-performance liquid chromatography.

    PubMed

    Aksnes, L

    1994-04-01

    Determination of the serum or plasma levels of retinol (vitamin A), 25-hydroxyvitamin D, and alpha-tocopherol (vitamin E) are the most frequently used parameters to evaluate status of vitamin A, D, and E, and also to assess the gastrointestinal absorption of the vitamins. We present a simple and sensitive method for simultaneous determination of these vitamins in 0.5 ml human serum or plasma. The vitamins were extracted from serum by methanol/iso-propanol (80/20, v/v) and n-hexane. The n-hexane phase was evaporated and injected to a reversed-phase (C-18) high-performance liquid chromatography system. Elution was performed with methanol/water (85:15, v/v) for 25-hydroxyvitamin D and retinol, and after that by methanol/water (98:2, v/v) for alpha-tocopherol. The eluate was monitored by a UV detector at 265 nm for detection of the vitamins. Baseline separation was obtained for all vitamins, and the system also permitted separate determinations of the D2 and D3 forms of 25-hydroxyvitamin D. The limit of detection and interassay variation for determination in 0.5 ml serum were 6.0 nmol/L and 6.2% for 25-hydroxyvitamin D2, 6 nmol/l and 6.1% for 25-hydroxyvitamin D3, 0.035 mumol/L and 5.0% for retinol, and 1.2 mumol/l and 5.5% for alpha-tocopherol.

  11. Sera of patients with high titers of immunoglobulin G against Toxoplasma gondii induce secretion of tumor necrosis factor alpha by human monocytes.

    PubMed Central

    Pelloux, H; Chumpitazi, B F; Santoro, F; Polack, B; Vuillez, J P; Ambroise-Thomas, P

    1992-01-01

    Toxoplasma gondii alone does not induce tumor necrosis factor alpha (TNF-alpha) secretion by human monocytes and macrophages. Nevertheless, sera from infected patients with high titers of specific immunoglobulin G antibodies against T. gondii induce TNF-alpha secretion, which is significantly higher than the corresponding induction by negative sera (P less than 0.05). After incubation with the positive serum, parasites also induce secretion of this cytokine, but TNF-alpha levels are lower (11.4 to 71.8%) than those obtained with positive serum alone. Therefore, this secretion seems to be elicited in part by antibody-T. gondii complexes and/or another unidentified factor(s), probably different from lipopolysaccharide, interleukin-1, TNF-alpha, and gamma interferon. In this study, monocytes secreted more TNF-alpha into the culture fluid than macrophages did (P less than 0.05), and no correlation was observed between secretion of this cytokine by the monocytes and the intracellular multiplication of the parasites, evaluated by [3H]uracil incorporation. Sera from patients with other infections diseases did not induce secretion of TNF-alpha; however, serum free of antibodies to T. gondii, obtained from patients with leishmaniosis, also stimulated secretion of the cytokine. PMID:1612737

  12. Antitumor activity of tumor necrosis factor-alpha conjugated with polyvinylpyrrolidone on solid tumors in mice.

    PubMed

    Kamada, H; Tsutsumi, Y; Yamamoto, Y; Kihira, T; Kaneda, Y; Mu, Y; Kodaira, H; Tsunoda, S I; Nakagawa, S; Mayumi, T

    2000-11-15

    We attempted the development of a novel polymer conjugation to further improve the therapeutic potency of antitumor cytokines compared with PEGylation for clinical application. Compared with native tumor necrosis factor (TNF)-alpha in vitro, specific bioactivities of polyvinyl-pyrrolidone (PVP)-modified TNF-alphas (PVP-TNF-alphas) were decreased by increasing the degree of PVP attachment. PVP-TNF-alpha fraction 3, Mr 101,000, had the most effective antitumor activity of the various PVP-TNF-alphas in vivo. PVP-TNF-alpha fraction 3 had >200-fold higher antitumor effect than native TNF-alpha, and the antitumor activity of PVP-TNF-alpha fraction 3 was >2-fold higher than that of MPEG-TNF-alpha (Mr 108,000), which had the highest antitumor activity among the polyethylene glycol (PEG)-conjugated TNF-alphas. Additionally, a high dose of native TNF-alpha induced toxic side effects such as body weight reduction, piloerection. and tissue inflammation, whereas no side effects were observed after i.v. administration of PVP-TNF-alpha fraction 3. The plasma half-life of PVP-TNF-alpha fraction 3 (360 min) was about 80- and 3-fold longer than those of native TNF-alpha (4.6 mm) and MPEG-TNF-alpha (122 min), respectively. The mechanism of increased antitumor effect in vivo caused the prolongation of plasma half-life and increase in stability. These results suggested that PVP is a useful polymeric modifier for bioconjugation of TNF-alpha to increase its antitumor potency, and multifunctionally bioconjugated TNF-alpha may be a potentiated antitumor agent for clinical use.

  13. Positive/Negative Mid Uv Resists With High Thermal Stability

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi; Wilson, C. G.; Frechet, Jean M.

    1987-08-01

    New mid UV resist systems based on poly(p-vinylbenzoates) sensitized with diphenyl-4-thiophenoxyphenylsulfonium hexafluoroantimonate are described. t-Butyl, cyclohexenyl, a-methylbenzyl, and a-methylallyl esters are converted upon postbake to poly(p-vinylbenzoic acid) through thermolysis reaction catalyzed by the photochemically generated Bronsted acid, inducing a large change in the polarity of the repeating units. Thus, development in aqueous base such as MF312/water or alcohol provides a positive tone image of the mask, while the use of a nonpolar organic developer allows a negative tone imaging. Because the glass transition temperature of poly(p-vinylbenzoic acid) is ca. 250° C, the negative image is devoid of thermal flow to this temperature even without any hardening processes. Another interesting feature of the benzoate resists is their high opacity in the deep UV region. The optical density of a 1μ thick film of poly(p-vinylbenzoic acid) is 3.5 at 254 nm and the benzoate polymers are as absorbing as the acid polymer. This high deep UV absorption of the resin necessitates the imaging above 300 nm for good light penetration (or by e-beam or X-ray) and makes the use of this resist as an imaging layer in the PCM scheme very attractive. This imaging layer is especially useful when employed in conjunction with a planarizing layer absorbing above 240 nm (for example, PMGI) as addition of a dye is not required.

  14. Flexible body dynamic stability for high performance aircraft

    NASA Technical Reports Server (NTRS)

    Goforth, E. A.; Youssef, H. M.; Apelian, C. V.; Schroeder, S. C.

    1991-01-01

    Dynamic equations which include the effects of unsteady aerodynamic forces and a flexible body structure were developed for a free flying high performance fighter aircraft. The linear and angular deformations are assumed to be small in the body reference frame, allowing the equations to be linearized in the deformation variables. Equations for total body dynamics and flexible body dynamics are formulated using the hybrid coordinate method and integrated in a state space format. A detailed finite element model of a generic high performance fighter aircraft is used to generate the mass and stiffness matrices. Unsteady aerodynamics are represented by a rational function approximation of the doublet lattice matrices. The equations simplify for the case of constant angular rate of the body reference frame, allowing the effect of roll rate to be studied by computing the eigenvalues of the system. It is found that the rigid body modes of the aircraft are greatly affected by introducing a constant roll rate, while the effect on the flexible modes is minimal for this configuration.

  15. Alpha-PVP as an active component of herbal highs in Poland between 2013 and 2015.

    PubMed

    Byrska, Bogumiła; Stanaszek, Roman; Zuba, Dariusz

    2016-12-30

    Alpha-PVP (alpha-pyrrolidinovalerophenone, α-PVP) is a synthetic derivative of cathinone. It has been one of the most frequently detected new psychoactive substances (NPS) available on the drug market in recent years in Poland. The usual routes of administration of the drug include oral, insufflation, and injection. Unexpectedly, we dealt with a great number of herbal samples that turned out to contain α-PVP. A total number of 352 herbal samples from 19 cases in which we detected synthetic cathinones, were investigated in the Institute of Forensic Research (IFR) from 2013 to 2015. The seized products that were received by our laboratory were first screened by gas chromatography coupled to mass spectrometry (GC-MS). Quantification of α-PVP and other cathinones was performed by ultra-performance liquid chromatography with photodiode array detection (UPLC-PDA). Of the samples, 84% contained only α-PVP. Other groups of products were those containing only α-PVT, α-PVP and α-PVT, α-PVP and synthetic cannabinoid A-834, 735, and α-PVP and cannabis. In one herbal sample, α-PVP was detected along with caffeine and tadalafil. The herbal products present on the market containing only α-PVP usually had a mass of 0.3 to 0.6 g, and concentration range in this group of samples was 3.0-44.0% (content: 13.0-222.0 mg per package). The amount of α-PVP in samples below 0.30 g was in a range 9-18 mg whiles in samples above 0.60 g it was in the range 30-716 mg. There were also products containing a mixture of α-PVP and α-PVT. In those samples, α-PVP concentrations were: 3.0-6.0% (amount: 15.0-34.0 mg). Copyright © 2016 John Wiley & Sons, Ltd.

  16. Hexacoordinated nitrogen(V) stabilized by high pressure

    NASA Astrophysics Data System (ADS)

    Kurzydłowski, Dominik; Zaleski-Ejgierd, Patryk

    2016-11-01

    In all of its known connections nitrogen retains a valence shell electron count of eight therefore satisfying the golden rule of chemistry - the octet rule. Despite the diversity of nitrogen chemistry (with oxidation states ranging from + 5 to -3), and despite numerous efforts, compounds containing nitrogen with a higher electron count (hypervalent nitrogen) remain elusive and are yet to be synthesized. One possible route leading to nitrogen’s hypervalency is the formation of a chemical moiety containing pentavalent nitrogen atoms coordinated by more than four substituents. Here, we present theoretical evidence that a salt containing hexacoordinated nitrogen(V), in the form of an NF6- anion, could be synthesized at a modest pressure of 40 GPa (=400 kbar) via spontaneous oxidation of NF3 by F2. Our results indicate that the synthesis of a new class of compounds containing hypervalent nitrogen is within reach of current high-pressure experimental techniques.

  17. Elastic stability of high dose neutron irradiated spinel

    SciTech Connect

    Li, Z.; Chan, S.K.; Garner, F.A.

    1995-04-01

    The objective of this effort is to identify ceramic materials that are suitable for fusion reactor applications. Elastic constants (C{sub 11}, C{sub 12}, and C{sub 44}) of spinel (MgAl{sub 2}O{sub 4}) single crystals irradiated to very high neutron fluences have geen measured by an ultrasonic technique. Although results of a neutron diffraction study show that cation occupation sites are significantly changed in the irradiated samples, no measurable differences occurred in their elastic properties. In order to understand such behavior, the elastic properties of a variety of materials with either normal or inverse spinel structures were studied. The cation valence and cation distribution appear to have little influence on the elastic properties of spinel materials.

  18. Unforeseen high temperature and humidity stability of FeCl3 intercalated few layer graphene

    PubMed Central

    Wehenkel, Dominique Joseph; Bointon, Thomas Hardisty; Booth, Tim; Bøggild, Peter; Craciun, Monica Felicia; Russo, Saverio

    2015-01-01

    We present the first systematic study of the stability of the structure and electrical properties of FeCl3 intercalated few-layer graphene to high levels of humidity and high temperature. Complementary experimental techniques such as electrical transport, high resolution transmission electron microscopy and Raman spectroscopy conclusively demonstrate the unforseen stability of this transparent conductor to a relative humidity up to 100% at room temperature for 25 days, to a temperature up to 150°C in atmosphere and to a temperature as high as 620°C in vacuum, that is more than twice higher than the temperature at which the intercalation is conducted. The stability of FeCl3 intercalated few-layer graphene together with its unique values of low square resistance and high optical transparency, makes this material an attractive transparent conductor in future flexible electronic applications. PMID:25567796

  19. Beam extraction and high stability operation of high current electron cyclotron resonance proton ion source

    SciTech Connect

    Roychowdhury, P. Mishra, L.; Kewlani, H.; Mittal, K. C.; Patil, D. S.

    2014-03-15

    A high current electron cyclotron resonance proton ion source is designed and developed for the low energy high intensity proton accelerator at Bhabha Atomic Research Centre. The plasma discharge in the ion source is stabilized by minimizing the reflected microwave power using four stub auto tuner and magnetic field. The optimization of extraction geometry is performed using PBGUNS code by varying the aperture, shape, accelerating gap, and the potential on the electrodes. While operating the source, it was found that the two layered microwave window (6 mm quartz plate and 2 mm boron nitride plate) was damaged (a fine hole was drilled) by the back-streaming electrons after continuous operation of the source for 3 h at beam current of 20–40 mA. The microwave window was then shifted from the line of sight of the back-streaming electrons and located after the water-cooled H-plane bend. In this configuration the stable operation of the high current ion source for several hours is achieved. The ion beam is extracted from the source by biasing plasma electrode, puller electrode, and ground electrode to +10 to +50 kV, −2 to −4 kV, and 0 kV, respectively. The total ion beam current of 30–40 mA is recorded on Faraday cup at 40 keV of beam energy at 600–1000 W of microwave power, 800–1000 G axial magnetic field and (1.2–3.9) × 10{sup −3} mbar of neutral hydrogen gas pressure in the plasma chamber. The dependence of beam current on extraction voltage, microwave power, and gas pressure is investigated in the range of operation of the ion source.

  20. Beam extraction and high stability operation of high current electron cyclotron resonance proton ion source.

    PubMed

    Roychowdhury, P; Mishra, L; Kewlani, H; Patil, D S; Mittal, K C

    2014-03-01

    A high current electron cyclotron resonance proton ion source is designed and developed for the low energy high intensity proton accelerator at Bhabha Atomic Research Centre. The plasma discharge in the ion source is stabilized by minimizing the reflected microwave power using four stub auto tuner and magnetic field. The optimization of extraction geometry is performed using PBGUNS code by varying the aperture, shape, accelerating gap, and the potential on the electrodes. While operating the source, it was found that the two layered microwave window (6 mm quartz plate and 2 mm boron nitride plate) was damaged (a fine hole was drilled) by the back-streaming electrons after continuous operation of the source for 3 h at beam current of 20-40 mA. The microwave window was then shifted from the line of sight of the back-streaming electrons and located after the water-cooled H-plane bend. In this configuration the stable operation of the high current ion source for several hours is achieved. The ion beam is extracted from the source by biasing plasma electrode, puller electrode, and ground electrode to +10 to +50 kV, -2 to -4 kV, and 0 kV, respectively. The total ion beam current of 30-40 mA is recorded on Faraday cup at 40 keV of beam energy at 600-1000 W of microwave power, 800-1000 G axial magnetic field and (1.2-3.9) × 10(-3) mbar of neutral hydrogen gas pressure in the plasma chamber. The dependence of beam current on extraction voltage, microwave power, and gas pressure is investigated in the range of operation of the ion source.

  1. The influence of barley malt protein modification on beer foam stability and their relationship to the barley dimeric alpha-amylase inhibitor-I (BDAI-I) as a possible foam-promoting protein.

    PubMed

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

    2008-02-27

    The foam stability of beer is one of the important key factors in evaluating the quality of beer. The purpose of this study was to investigate the relationship between the level of malt modification (degradation of protein, starch, and so on) and the beer foam stability. This was achieved by examining foam-promoting proteins using two-dimensional gel electrophoresis (2DE). We found that the foam stability of beer samples brewed from the barley malts of cultivars B and C decreased as the level of malt modification increased; however, the foam stability of cultivar A did not change. To identify the property providing the increased foam stability of cultivar A, we analyzed beer proteins using 2DE. We analyzed three fractions that could contain beer foam-promoting proteins, namely, beer whole proteins, salt-precipitated proteins, and the proteins concentrated from beer foam. As a result, we found that in cultivar A, some protein spots did not change in any of these three protein fractions even when the level of malt modification increased, although the corresponding protein spots in cultivars B and C decreased. We analyzed these protein spots by peptide mass finger printing using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. As a result, all of these spots were identified as barley dimeric alpha-amylase inhibitor-I (BDAI-I). These results suggest that BDAI-I is an important contributor to beer foam stability.

  2. Photonic crystal fiber-based immunosensor for high-performance detection of alpha fetoprotein.

    PubMed

    Liu, Xiaoxia; Song, Xingda; Dong, Zhiyong; Meng, Xiaoting; Chen, Yiping; Yang, Li

    2017-05-15

    We have developed a sensitive photonic crystal fiber (PCF)-based immunosensor for detection of alpha fetoprotein (AFP). The unique PCF possesses a morphology characterized by numerous pore structures and a large surface area-to-volume ratio, which can be used as an immune-reaction carrier to improve the sensitivity and reaction speed of AFP detection. The PCF-based immunosensor possesses a low limit of detection of 0.1ng/mL, which is five times lower than that of the capillary-based sensor and 35 times lower than that of the traditional enzyme-linked immunosorbent assay. The wide linear dynamic range of 0.1-150ng/mL makes the developed immunosensor suitable for clinical practice. The proposed method was successfully applied to AFP detection in a clinical serum sample with acceptable precision. It is indicated that the present PCF-based immunosensor could be used as an attractive analytical platform for sensitive and specific detection of cancer biomarkers.

  3. High diversity of {alpha}-globin haplotypes in a senegalese population, including many previously unreported variants

    SciTech Connect

    Martinson, J.J.; Swinburn, C.; Clegg, J.B.

    1995-11-01

    RFLP haplotypes at the {alpha}-globin gene complex have been examined in 190 individuals from the Niokolo Mandenka population of Senegal: haplotypes were assigned unambiguously for 210 chromosomes. The Mandenka share with other African populations a sample size-independent haplotype diversity that is much greater than that in any non-African population: the number of haplotypes observed in the Mandenka is typically twice that seen in the non-African populations sampled to date. Of these haplotypes, 17.3% had not been observed in any previous surveys, and a further 19.1% have previously been reported only in African populations. The haplotype distribution shows clear differences between African and non-African peoples, but this is on the basis of population-specific haplotypes combined with haplotypes common to all. The relationship of the newly reported haplotypes to those previously recorded suggests that several mutation processes, particularly recombination as homologous exchange or gene conversion, have been involved in their production. A computer program based on the expectation-maximization (EM) algorithm was used to obtain maximum-likelihood estimates of haplotype frequencies for the entire data set: good concordance between the unambiguous and EM-derived sets was seen for the overall haplotype frequencies. Some of the low-frequency haplotypes reported by the estimation algorithm differ greatly, in structure, from those haplotypes known to be present in human populations, and they may not represent haplotypes actually present in the sample. 43 refs., 4 figs., 4 tabs.

  4. Cerebral artery alpha-1 AR subtypes: high altitude long-term acclimatization responses.

    PubMed

    Goyal, Ravi; Goyal, Dipali; Chu, Nina; Van Wickle, Jonathan; Longo, Lawrence D

    2014-01-01

    In response to hypoxia and other stress, the sympathetic (adrenergic) nervous system regulates arterial contractility and blood flow, partly through differential activities of the alpha1 (α1) - adrenergic receptor (AR) subtypes (α1A-, α1B-, and α1D-AR). Thus, we tested the hypothesis that with acclimatization to long-term hypoxia (LTH), contractility of middle cerebral arteries (MCA) is regulated by changes in expression and activation of the specific α1-AR subtypes. We conducted experiments in MCA from adult normoxic sheep maintained near sea level (300 m) and those exposed to LTH (110 days at 3801 m). Following acclimatization to LTH, ovine MCA showed a 20% reduction (n = 5; P<0.05) in the maximum tension achieved by 10-5 M phenylephrine (PHE). LTH-acclimatized cerebral arteries also demonstrated a statistically significant (P<0.05) inhibition of PHE-induced contractility in the presence of specific α1-AR subtype antagonists. Importantly, compared to normoxic vessels, there was significantly greater (P<0.05) α1B-AR subtype mRNA and protein levels in LTH acclimatized MCA. Also, our results demonstrate that extracellular regulated kinase 1 and 2 (ERK1/2)-mediated negative feedback regulation of PHE-induced contractility is modulated by α1B-AR subtype. Overall, in ovine MCA, LTH produces profound effects on α1-AR subtype expression and function.

  5. Cerebral Artery Alpha-1 AR Subtypes: High Altitude Long-Term Acclimatization Responses

    PubMed Central

    Goyal, Ravi; Goyal, Dipali; Chu, Nina; Van Wickle, Jonathan; Longo, Lawrence D.

    2014-01-01

    In response to hypoxia and other stress, the sympathetic (adrenergic) nervous system regulates arterial contractility and blood flow, partly through differential activities of the alpha1 (α1) - adrenergic receptor (AR) subtypes (α1A-, α1B-, and α1D-AR). Thus, we tested the hypothesis that with acclimatization to long-term hypoxia (LTH), contractility of middle cerebral arteries (MCA) is regulated by changes in expression and activation of the specific α1-AR subtypes. We conducted experiments in MCA from adult normoxic sheep maintained near sea level (300 m) and those exposed to LTH (110 days at 3801 m). Following acclimatization to LTH, ovine MCA showed a 20% reduction (n = 5; P<0.05) in the maximum tension achieved by 10−5 M phenylephrine (PHE). LTH-acclimatized cerebral arteries also demonstrated a statistically significant (P<0.05) inhibition of PHE-induced contractility in the presence of specific α1-AR subtype antagonists. Importantly, compared to normoxic vessels, there was significantly greater (P<0.05) α1B-AR subtype mRNA and protein levels in LTH acclimatized MCA. Also, our results demonstrate that extracellular regulated kinase 1 and 2 (ERK1/2)-mediated negative feedback regulation of PHE-induced contractility is modulated by α1B-AR subtype. Overall, in ovine MCA, LTH produces profound effects on α1-AR subtype expression and function. PMID:25393740

  6. High diversity of alpha-globin haplotypes in a Senegalese population, including many previously unreported variants.

    PubMed Central

    Martinson, J J; Excoffier, L; Swinburn, C; Boyce, A J; Harding, R M; Langaney, A; Clegg, J B

    1995-01-01

    RFLP haplotypes at the alpha-globin gene complex have been examined in 190 individuals from the Niokolo Mandenka population of Senegal: haplotypes were assigned unambiguously for 210 chromosomes. The Mandenka share with other African populations a sample size-independent haplotype diversity that is much greater than that in any non-African population: the number of haplotypes observed in the Mandenka is typically twice that seen in the non-African populations sampled to date. Of these haplotypes, 17.3% had not been observed in any previous surveys, and a further 19.1% have previously been reported only in African populations. The haplotype distribution shows clear differences between African and non-African peoples, but this is on the basis of population-specific haplotypes combined with haplotypes common to all. The relationship of the newly reported haplotypes to those previously recorded suggests that several mutation processes, particularly recombination as homologous exchange or gene conversion, have been involved in their production. A computer program based on the expectation-maximization (EM) algorithm was used to obtain maximum-likelihood estimates of haplotype frequencies for the entire data set: good concordance between the unambiguous and EM-derived sets was seen for the overall haplotype frequencies. Some of the low-frequency haplotypes reported by the estimation algorithm differ greatly, in structure, from those haplotypes known to be present in human populations, and they may not represent haplotypes actually present in the sample. PMID:7485171

  7. Combination treatment with high-dose vitamin C and alpha-tocopherol does not enhance respiratory-tract lining fluid vitamin C levels in asthmatics.

    PubMed

    Hernandez, Michelle; Zhou, Haibo; Zhou, Bingqing; Robinette, Carole; Crissman, Kay; Hatch, Gary; Alexis, Neil E; Peden, David

    2009-02-01

    Oxidative stress plays a significant role in allergic airway inflammation. Supplementation with alpha-tocopherol (alone or combined with ascorbate/vitamin C) has been assessed as an intervention for allergic airway diseases with conflicting results. Enhancing levels of airway antioxidants with oral supplements has been suggested as an intervention to protect individuals from the effect of inhaled oxidants, although it is unclear whether supplementation changes tocopherol or vitamin C levels in both serum and airway fluids. Our objective was to obtain pilot safety and dosing data from 14 allergic asthmatic volunteers examining the effect of daily combination oral therapy with 500 mg alpha-tocopherol (alpha T) and 2 g vitamin C for 12 wk. We examined serum and airway fluid and cellular levels of alpha- and gamma-tocopherol (gamma T) and vitamin C to plan for future studies of these agents in asthma and allergic rhinitis. Six volunteers completed 12 wk of active treatment with alpha T and vitamin C and 8 completed placebo. Blood and sputum samples were obtained at baseline and at 6 wk and 12 wk of therapy and were analyzed for alpha T, gamma T, and vitamin C levels in the serum, sputum supernatant, and sputum cells. Combination treatment increased serum vitamin C and significantly decreased sputum alpha T and serum gamma T levels. No changes were found in sputum supernatant or sputum cell vitamin C or serum alpha T levels in the active treatment group. In conclusion, supplementation with alpha T and high-dose vitamin C does not augment vitamin C levels in the respiratory-tract lining fluid.

  8. Stabilized Acoustic Levitation of Dense Materials Using a High-Powered Siren

    NASA Technical Reports Server (NTRS)

    Gammell, P. M.; Croonquist, A.; Wang, T. G.

    1982-01-01

    Stabilized acoustic levitation and manipulation of dense (e.g., steel) objects of 1 cm diameter, using a high powered siren, was demonstrated in trials that investigated the harmonic content and spatial distribution of the acoustic field, as well as the effect of sample position and reflector geometries on the acoustic field. Although further optimization is possible, the most stable operation achieved is expected to be adequate for most containerless processing applications. Best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper one. Operation slightly below resonance enhances stability as this minimizes the second harmonic, which is suspected of being a particularly destabilizing influence.

  9. Stabilized acoustic levitation of dense materials using a high-powered siren

    NASA Astrophysics Data System (ADS)

    Gammell, P. M.; Croonquist, A.; Wang, T. G.

    1982-12-01

    Stabilized acoustic levitation and manipulation of dense (e.g., steel) objects of 1 cm diameter, using a high powered siren, was demonstrated in trials that investigated the harmonic content and spatial distribution of the acoustic field, as well as the effect of sample position and reflector geometries on the acoustic field. Although further optimization is possible, the most stable operation achieved is expected to be adequate for most containerless processing applications. Best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper one. Operation slightly below resonance enhances stability as this minimizes the second harmonic, which is suspected of being a particularly destabilizing influence.

  10. In Vivo Oxidative Stability Changes of Highly Cross-Linked Polyethylene Bearings: An Ex Vivo Investigation.

    PubMed

    Rowell, Shannon L; Reyes, Christopher R; Malchau, Henrik; Muratoglu, Orhun K

    2015-10-01

    The development of highly cross-linked UHMWPEs focused on stabilizing radiation-induced free radicals as the sole precursor to oxidative degradation. However, secondary in vivo oxidation mechanisms have been discovered. After a preliminary post-operative analysis, we subjected highly cross-linked retrievals with 1-4 years in vivo durations and never-implanted controls to accelerated aging to predict the extent to which their oxidative stability was compromised in vivo. Lipid absorption, oxidation, and hydroperoxides were measured using infrared spectroscopy. Gravimetric swelling was used to measure cross-link density. After aging, all retrievals, except vitamin E-stabilized components, regardless of initial lipid levels or oxidation, showed significant oxidative degradation, demonstrated by subsurface oxidative peaks, increased hydroperoxides and decreased cross-link density, compared to their post-operative material properties and never-implanted counterparts, confirming oxidative stability changes.

  11. High cycle fatigue life improvement of polycrystalline alpha-iron modified by silver, chromium, aluminium, and yttrium ion implantation

    SciTech Connect

    Wang, H.W.; Yang, D.Z.; Shi, W.D.; Patu, S.

    1995-06-15

    Body-centered cubic (bcc) metals are at least of parallel significance to fcc ones. Work on bcc metal`s fatigue modification by ion implantation is rare. The asymmetry deformation and high SFE characteristics in the microplasticity of bcc metals make the fatigue process more complex. The authors have chosen polycrystalline alpha-iron as the target metal to be implanted with silver, chromium, aluminium, and yttrium ions, which are mutually immiscible, limited soluble without precipitation, and soluble with precipitation in iron, respectively. This work aims at providing a systematic investigation on different mechanisms dominant in fatigue. This brief report is on the high cycle fatigue (HCF) property improvement by these metallic ion implantations, which is part of a series of reports both on HCF and low cycle fatigue (LCF) modifications by each individual ion implantation.

  12. High magnetic shear gain in a liquid sodium stable couette flow experiment A prelude to an alpha - omega dynamo

    SciTech Connect

    Colgate, Stirling; Li, Jui; Finn, John; Pariev, Vladimir; Beckley, Howard; Si, Jiahe; Martinic, Joe; Westpfahl, David; Slutz, James; Westrom, Zeb; Klein, Brianna

    2010-11-08

    The {Omega}-phase of the liquid sodium {alpha}-{Omega} dynamo experiment at NMIMT in cooperation with LANL has successfully demonstrated the production of a high toroidal field, B{sub {phi}} {approx_equal} 8 x B{sub r} from the radial component of an applied poloidal magnetic field, B{sub r}. This enhanced toroidal field is produced by rotational shear in stable Couette Row within liquid sodium at Rm {approx_equal} 120. The small turbulence in stable Taylor-Couette Row is caused by Ekman Row where ({delta}v/v){sup 2} {approx} 10{sup -3}. This high {Omega}-gain in low turbulence flow contrasts with a smaller {Omega}-gain in higher turbulence, Helmholtz-unstable shear flows. This result supports the ansatz that large scale astrophysical magnetic fields are created within semi-coherent large scale motions in which turbulence plays a diffusive role that enables magnetic flux linkage.

  13. High-level expression of biologically active human alpha 1-antitrypsin in the milk of transgenic mice.

    PubMed Central

    Archibald, A L; McClenaghan, M; Hornsey, V; Simons, J P; Clark, A J

    1990-01-01

    Reduced circulating levels of alpha 1-antitrypsin (alpha 1 AT) are associated with certain alpha 1 AT genotypes and increased susceptibility to emphysema. Unfortunately, the amounts of alpha 1 AT that would be required for replacement therapy are beyond the capacity of plasma fractionation and mammalian cell culture systems. Thus, we have examined the potential of transgenic animals as an alternative means of producing human alpha 1 AT. A hybrid gene constructed by using sequences from the ovine milk protein gene beta-lactoglobulin fused to an alpha 1 AT "minigene" was used to generate transgenic mice. Of 13 independent transgenic mice and mouse lines, 5 expressed the hybrid gene in the mammary gland, 5 in the salivary glands, and 2 in both these tissues. Human alpha 1 AT was secreted into the milk of each of the 7 mice and mouse lines that expressed the hybrid gene in the mammary gland. Four of these mammary-expressing transgenic mice and mouse lines produced concentrations of at least 0.5 mg of alpha 1 AT per ml in their milk; one line (AATB 35) produced 7 mg of this protein per ml. alpha 1 AT from transgenic mouse milk was similar in size to human plasma-derived alpha 1 AT and showed a similar capacity to inhibit trypsin. Expression at equivalent levels in transgenic sheep or cattle would yield sufficient alpha 1 AT for therapeutic purposes. Images PMID:1695012

  14. Alpha particle destabilization of the toroidicity-induced Alfven eigenmodes

    SciTech Connect

    Cheng, C.Z.

    1990-10-01

    The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped {alpha}-particles through the wave-particle resonances. Satisfying the resonance condition requires that the {alpha}-particle birth speed v{sub {alpha}} {ge} v{sub A}/2{vert bar}m-nq{vert bar}, where v{sub A} is the Alfven speed, m is the poloidal model number, and n is the toroidal mode number. To destabilize the TAE modes, the inverse Landau damping associated with the {alpha}-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the {alpha}-particles and the core electrons and ions. The growth rate was studied analytically with a perturbative formula derived from the quadratic dispersion relation, and numerically with the aid of the NOVA-K code. Stability criteria in terms of the {alpha}-particle beta {beta}{sub {alpha}}, {alpha}-particle pressure gradient parameter ({omega}{sub {asterisk}}/{omega}{sub A}) ({omega}{sub {asterisk}} is the {alpha}-particle diamagnetic drift frequency), and (v{sub {alpha}}/v{sub A}) parameters will be presented for TFTR, CIT, and ITER tokamaks. The volume averaged {alpha}-particle beta threshold for TAE instability also depends sensitively on the core electron and ion temperature. Typically the volume averaged {alpha}-particle beta threshold is in the order of 10{sup {minus}4}. Typical growth rates of the n=1 TAE mode can be in the order of 10{sup {minus}2}{omega}{sub A}, where {omega}{sub A}=v{sub A}/qR. Other types of global Alfven waves are stable in D-T tokamaks due to toroidal coupling effects.

  15. Hydrogel-stabilized droplet bilayers for high speed solution exchange.

    PubMed

    Acharya, Shiv A; Portman, Alexander; Salazar, Carl S; Schmidt, Jacob J

    2013-11-05

    Many applications utilizing artificial lipid bilayers require the ability to exchange the bilayer's solution environment. However, because of the instability of the bilayer, the rate of solution exchange is limited, which significantly hinders the measurement rate and throughput. We have developed an artificial bilayer system that can withstand high flow speeds, up to 2.1 m/s, by supporting the bilayer with a hydrogel. We demonstrated the ability to measure during flow by measuring the conductance of gramicidin-A channels while switching between solutions of two different compositions, recording a time to measure 90% change in current of approximately 2.7 seconds at a flow rate of 0.1 m/s. We also demonstrated a potential application of this system by measuring the conductance modulation of the rat TRPM8 ion channel by an agonist and antagonist at varying concentrations, obtaining 7-point IC50 and EC50 values in approximately 7 minutes and 4-point values within 4 minutes.

  16. THE STABILITY AND ELECTRICAL PROPERTIES OF HIGH TEMPERATURE PROTON CONDUCTORS

    SciTech Connect

    Brinkman, K.

    2010-07-06

    The morphological and electrical properties of Ba{sub 1-x}Sr{sub x}Ce{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} with x varying from 0 to 1 prepared by a modified Pechini method were investigated as potential high temperature proton conductors. Dense microstructures were achieved for all the samples upon sintering at 1500 C for 5 h. The phase structure analysis indicated that perovskite phase was formed for 0 {le} x {le} 0.2, while for x larger than 0.5, impurity phases of Sr{sub 2}CeO{sub 4} and Y{sub 2}O{sub 3} appeared. The tolerance to H{sub 2}O for the samples improved with the increase in Sr content when exposed to boiling water, while the electrical conductivity decreased from x = 0 to 1. However, the resistance to CO{sub 2} attack at elevated temperatures was not improved within the whole x range studied.

  17. Hexacoordinated nitrogen(V) stabilized by high pressure

    PubMed Central

    Kurzydłowski, Dominik; Zaleski-Ejgierd, Patryk

    2016-01-01

    In all of its known connections nitrogen retains a valence shell electron count of eight therefore satisfying the golden rule of chemistry - the octet rule. Despite the diversity of nitrogen chemistry (with oxidation states ranging from + 5 to −3), and despite numerous efforts, compounds containing nitrogen with a higher electron count (hypervalent nitrogen) remain elusive and are yet to be synthesized. One possible route leading to nitrogen’s hypervalency is the formation of a chemical moiety containing pentavalent nitrogen atoms coordinated by more than four substituents. Here, we present theoretical evidence that a salt containing hexacoordinated nitrogen(V), in the form of an NF6− anion, could be synthesized at a modest pressure of 40 GPa (=400 kbar) via spontaneous oxidation of NF3 by F2. Our results indicate that the synthesis of a new class of compounds containing hypervalent nitrogen is within reach of current high-pressure experimental techniques. PMID:27808104

  18. 7alpha-methyl-19-nortestosterone, a synthetic androgen with high potency: structure-activity comparisons with other androgens.

    PubMed

    Kumar, N; Crozat, A; Li, F; Catterall, J F; Bardin, C W; Sundaram, K

    1999-12-31

    CNNT. There was a good correlation between bioactivity and binding affinity to AR for the 7alpha-substituted androgens compared to T. In contrast, relative to their binding affinity to AR, the androgenic potency of DHT and 19-NT was lower compared to T. The reason for the lower in vivo androgenic activity of 19-NT is attributable to its enzymatic conversion to 5alpha-reduced-19-NT in the prostate. In the case of DHT, the lower bioactivity could be attributed to its faster metabolic clearance rate relative to T. The correlation was further investigated in vitro by co-transfection of rat ARcDNA expression plasmid and a reporter plasmid encoding the chloramphenicol acetyl transferase (CAT) gene driven by an androgen inducible promoter into CV-1 cells. All the androgens led to a dose-dependent increase in the CAT activity. MENT was found to be the most potent followed by DHT, 19-NT, T, and CNNT. The specificity of the androgenic response was confirmed by its inhibition with hydroxyflutamide, an antiandrogen. Thus, there was a good correlation between binding affinity and in vitro bioactivity in the transient transfection assay for the androgens. This suggests that the in vivo bioactivity of androgens could be influenced not only by binding affinity to receptors but also by factors such as absorption, binding to serum proteins and metabolism. However, the high potency of MENT is primarily related to its higher affinity to AR.

  19. High-resolution measurements, line identification, and spectral modeling of K-alpha transitions in Fe XVIII-Fe XXV

    NASA Technical Reports Server (NTRS)

    Beiersdorfer, P.; Phillips, T.; Jacobs, V. L.; Hill, K. W.; Bitter, M.; Von Goeler, S.; Kahn, S. M.

    1993-01-01

    A detailed analysis of the iron K-alpha emission spectrum covering the wavelength region from 1.840 to 1.940 A is presented. Measurements are made with a high-resolution Bragg crystal spectrometer on the Princeton Large Torus (PLT) tokamak for plasma conditions which closely resemble those of solar flares. A total of 40 features are identified, consisting of either single or multiple lines from eight charge states in iron, Fe XVIII - Fe XXV, and their wavelengths are determined with an accuracy of 0.1-0.4 mA. Many of these features are identified for the first time. In the interpretation of our observations we rely on model calculations that determine the ionic species abundances from electron density and temperature profiles measured independently with nonspectroscopic techniques and that incorporate theoretical collisional excitation and dielectronic recombination rates resulting in the excitation of the 1s2sr2ps configurations. The model calculations also include the effect of diffusive ion transport. Good overall agreement between the model calculations and the observations is obtained, which gives us confidence in our line identifications and spectral modeling capabilities. The results are compared with earlier analyses of the K-alpha emission from the Sun.

  20. Small-angle stability analysis of a linear control system for a high power communication satellite

    NASA Technical Reports Server (NTRS)

    Omalley, T. A.

    1972-01-01

    A small angle stability analysis is presented for one particular configuration of a high power communication satellite having a linear control system. Both the central body and the solar array are treated as rigid bodies. The control system studied consists of three-axis control of the central body and one-axis control of the solar array rotation relative to the central body. The results yield preliminary indications of the relation of stability to satellite inertias and control gains.

  1. Stability of High-Level Radioactive Waste Forms

    SciTech Connect

    Besmann, T.M.

    2001-06-22

    High-level waste (HLW) glass compositions, processing schemes, limits on waste content, and corrosion/dissolution release models are dependent on an accurate knowledge of melting temperatures and thermochemical values. Unfortunately, existing models for predicting these temperatures are empirically-based, depending on extrapolations of experimental information. In addition, present models of leaching behavior of glass waste forms use simplistic assumptions or experimentally measured values obtained under non-realistic conditions. There is thus a critical need for both more accurate and more widely applicable models for HLW glass behavior, which this project addressed. Significant progress was made in this project on modeling HLW glass. Borosilicate glass was accurately represented along with the additional important components that contain iron, lithium, potassium, magnesium, and calcium. The formation of crystalline inclusions in the glass, an issue in Hanford HLW formulations, was modeled and shown to be predictive. Thus the results of this work have already demonstrated practical benefits with the ability to map compositional regions where crystalline material forms, and therefore avoid that detrimental effect. With regard to a fundamental understanding, added insights on the behavior of the components of glass have been obtained, including the potential formation of molecular clusters. The EMSP project had very significant effects beyond the confines of Environmental Management. The models developed for glass have been used to solve a very costly problem in the corrosion of refractories for glass production. The effort resulted in another laboratory, Sandia National Laboratories-Livermore, to become conversant in the techniques and to apply those through a DOE Office of Industrial Technologies project joint with PPG Industries. The glass industry as a whole is now cognizant of these capabilities, and there is a Glass Manufacturer's Research Institute proposal

  2. Long term stability of magnetorheological fluids using high viscosity linear polysiloxane carrier fluids

    NASA Astrophysics Data System (ADS)

    Xie, Lei; Choi, Young-Tai; Liao, Chang-Rong; Wereley, Norman M.

    2016-07-01

    Stability of magnetorheological fluids (MRFs) or suspensions has been a key issue in the development of various practical applications. In our prior work, it was experimentally confirmed that a high viscosity linear polysiloxane carrier fluid based MRF (hereinafter HVLP MRF) with 26% particle volume fraction (hereinafter 26 vol%) showed high sedimentation stability for 96 days because HVLP carrier fluids have remarkable shear thinning behavior, that is, very high viscosity at low shear rate but low viscosity at high shear rate. In addition, the effects of HVLP carrier fluid viscosity and carbonyl iron (CI) particle concentration on suspension stability were investigated with the objective of synthesizing highly stable HVLP MRFs for practical applications. The HVLP MRFs were synthesized by suspending nominally 32 vol% of CI particles in carrier fluids with different viscosities (i.e., 140, 440, and 800 Pa s). To illustrate the effect of particle concentration on suspension stability, because it is well known that suspension stability increases as particle concentration increases, two low concentrations, 5 and 10 vol%, and two high concentrations, 20 and 32 vol%, were prepared to demonstrate MRFs with relatively severe sedimentation, and stable suspensions, respectively. A vertical axis inductance monitoring system was employed to evaluate the suspension stability of the HVLP MRFs for 365 days by scanning the inductance of the MRF samples in a vertical fluid column, and logging this data with respect to height and time. In addition, the suspension stability of a commercially available MRF (i.e., Lord MRF-132DG) was also measured and compared with similar measurements for HVLP MRFs.

  3. Optimization of alpha-amylase application in raw sugar manufacture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In recent years there have been warnings by some U.S. refineries that there may be a penalty for high starch concentration sin raw sugar if starch control is not improved. Most commercial alpha-amylases used by the U.S. sugar industry to control starch have intermediate temperature stability (up to...

  4. The stability of retinol, alpha-tocopherol, trans-lycopene, and trans-beta-carotene in liquid-frozen and lyophilized serum.

    PubMed

    Brown Thomas, J; Duewer, D L; Kline, M C; Sharpless, K E

    1998-08-10

    The concentrations of retinol, alpha-tocopherol, and trans-beta-carotene in lyophilized serum stored at -25 degrees C and -80 degrees C have been monitored for 10 years. There was no evidence of degradation of any of these compounds over the 10-year period. Retinol, alpha-tocopherol, and trans-beta-carotene were less stable at -25 degrees C in liquid-frozen serum than they were in lyophilized serum. At -80 degrees C, trans-beta-carotene levels were stable for up to 3 years of storage in liquid-frozen serum. Both retinol and alpha-tocopherol appeared stable in liquid-frozen serum for at least 5 years at -80 degrees C. The effect of repeated freeze/thaw cycles on retinol, alpha-tocopherol, trans-lycopene, and trans-beta-carotene in liquid-frozen and reconstituted lyophilized serum both stored at -20 degrees C was also studied. Retinol, alpha-tocopherol, trans-lycopene, and trans-beta-carotene in reconstituted lyophilized serum stored at -20 degrees C were stable for at least 3 days with minimal (< 5) freeze/thaw cycles.

  5. Substrate evokes translocation of both domains in the mitochondrial processing peptidase alpha-subunit during which the C-terminus acts as a stabilizing element.

    PubMed

    Janata, Jirí; Holá, Klára; Kubala, Martin; Gakh, Oleksandr; Parkhomenko, Natalya; Matusková, Anna; Kutejová, Eva; Amler, Evzen

    2004-03-26

    All three tryptophan residues in alpha-subunit of mitochondrial processing peptidase (MPP) were subsequently substituted. While substitutions of Trp223 led to misfolded non-functional protein, mutations of Trp147 and/or Trp481 did not affect the enzyme processing activity. Thus, fluorescence properties of the mutants with fewer tryptophans were used for observation of both alpha-MPP domain translocation and visualization of conformational changes in the interdomain linker evoked by substrate. We found that in the presence of substrate the C-terminal penultimate Trp481 was approaching Trp223, which is localized at the border of N-terminal domain and interdomain linker. Also, excision of the alpha-MPP C-terminal 30 amino acid residues (DeltaC30) led to a complete loss of protein function. Even shorter deletions of the alpha-MPP C-terminus destabilized the protein slightly (DeltaC2) or dramatically (DeltaC17). It suggests that the extreme C-terminus of alpha-MPP provides mechanical support to the C-terminal domain during its extensive conformational change accompanying the substrate recognition process.

  6. High-LET alpha-emitters: Radon, lung cancer and smoking

    SciTech Connect

    Fabrikant, J.I.

    1988-11-01

    The National Academy of Sciences BEIR IV Report deals with the health effects in human populations exposed to internally-deposited alpha-emitting radionuclides and their decay products. Quantitative risk estimates for cancer induction are derived, mainly from analyses of epidemiological data. The Report addresses the health outcomes of exposure to radon and its daughters, primarily lung cancer risks of worker exposure to radon progeny in underground mines and in the general public in indoor domestic environments. An excess relative risk model of lung cancer mortality and exposure to radon progeny is developed; this models the excess risk per Working Level Month in terms of time intervals prior to an attained age, and is dependent on time-since-exposure and age at risk. Risk projections are presented and cover exposure situations of current public health concern. For example, lifetime exposure to 1 WLM y/sup /minus/1/ is estimated to increase the number of deaths due to lung cancer by a factor of about 1.5 over the current rate for both males and females in a population having the current prevalence of cigarette-smoking. Occupational exposure to 4 WLM y/sup /minus/1/ from ages 20 y to 40 y is projected to increase lung cancer deaths by a factor of 1.6 over the current rate of this age cohort in the general population. In all of these cases, most of the increased risk occurs to smokers for whom the risk is up to ten times greater than for non-smokers. 8 refs., 1 tab.

  7. Imaging alpha particle detector

    DOEpatents

    Anderson, David F.

    1985-01-01

    A method and apparatus for detecting and imaging alpha particles sources is described. A conducting coated high voltage electrode (1) and a tungsten wire grid (2) constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source (3) to be quantitatively or qualitatively analyzed. A thin polyester film window (4) allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

  8. Imaging alpha particle detector

    DOEpatents

    Anderson, D.F.

    1980-10-29

    A method and apparatus for detecting and imaging alpha particles sources is described. A dielectric coated high voltage electrode and a tungsten wire grid constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source to be quantitatively or qualitatively analyzed. A thin polyester film window allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

  9. Core-Protected Platinum Monolayer Shell High-Stability Electrocatalysts for Fuel-Cell Cathodes

    SciTech Connect

    K Sasaki; H Naohara; Y Cai; Y Choi; P Liu; M Vukmirovic; J Wang; R Adzic

    2011-12-31

    Platinum monolayers can act as shells for palladium nanoparticles to lead to electrocatalysts with high activities and an ultralow platinum content, but high platinum utilization. The stability derives from the core protecting the shell from dissolution. In fuel-cell tests, no loss of platinum was observed in 200,000 potential cycles, whereas loss of palladium was significant.

  10. Core-Protected Platinum Monolayer Shell High-Stability Electrocatalysts for Fuel-Cell Cathodes

    SciTech Connect

    Adzic, R.R.; Sasaki, K.; Naohara, H.; Cai, Y.; Choi, Y.M.; Liu, P.; Vukmirovic, M.B.; Wang, J.X.

    2010-11-08

    More than skin deep: Platinum monolayers can act as shells for palladium nanoparticles to lead to electrocatalysts with high activities and an ultralow platinum content, but high platinum utilization. The stability derives from the core protecting the shell from dissolution. In fuel-cell tests, no loss of platinum was observed in 200?000 potential cycles, whereas loss of palladium was significant.

  11. An Overview of Controls and Flying Qualities Technology on the F/A-18 High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Pahle, Joseph W.; Wichman, Keith D.; Foster, John V.; Bundick, W. Thomas

    1996-01-01

    The NASA F/A-18 High Alpha Research Vehicle (HARV) has been the flight test bed of a focused technology effort to significantly increase maneuvering capability at high angles of attack. Development and flight test of control law design methodologies, handling qualities metrics, performance guidelines, and flight evaluation maneuvers are described. The HARV has been modified to include two research control effectors, thrust vectoring, and actuated forebody strakes in order to provide increased control power at high angles of attack. A research flight control system has been used to provide a flexible, easily modified capability for high-angle-of-attack research controls. Different control law design techniques have been implemented and flight-tested, including eigenstructure assignment, variable gain output feedback, pseudo controls, and model-following. Extensive piloted simulation has been used to develop nonlinear performance guide-lines and handling qualities criteria for high angles of attack. This paper reviews the development and evaluation of technologies useful for high-angle-of-attack control. Design, development, and flight test of the research flight control system, control laws, flying qualities specifications, and flight test maneuvers are described. Flight test results are used to illustrate some of the lessons learned during flight test and handling qualities evaluations.

  12. Pegylated protein encapsulated multivesicular liposomes: a novel approach for sustained release of interferon alpha.

    PubMed

    Vyas, S P; Rawat, M; Rawat, A; Mahor, S; Gupta, P N

    2006-07-01

    Hepatitis C viral chemotherapy suffers from a relatively short half-life of the interferon alpha-2a (IFN alpha). To address this issue, we investigated the effects of polyethylene glycol modification and their subsequent encapsulation in multivesicular liposomes (MVLs), on the release properties of IFN alpha. In the present study, interferon-alpha was conjugated with methoxy-polyethylene glycol (mPEG, MW 5000). Prepared IFN alpha-mPEG5000 conjugate (IFN alpha-mPEG5000) was purified with size exclusion chromatography. The relative in vitro anti-viral activity of pegylated interferon alpha-2a was found to 87.9% of the unmodified IFN alpha. Pegylated IFN alpha encapsulated multivesicular liposomes were prepared by double emulsification technique followed by evaporation of organic solvents from chloroform ether spherules suspended in water. Prepared MVLs were then characterized for shape, size, vesicle count, encapsulation efficiency, and in vitro release rate. In process stability studies of pegylated IFN alpha protein exhibited better stability when exposed to chloroform: diethyl ether (1:1 ratio) mixture as well as variable vortexing time as compared to native IFN alpha. Relatively high percentage of encapsulation of protein ( approximately 75%) was achieved. In vitro release profile of pegylated IFN alpha-mPEG5000 containing MVLs in the PBS showed lower initial burst release with sustained and incomplete release over a period of 1 week. In contrast, native IFN alpha entrapped MVLs were observed as higher initial burst release, i.e., nearly 35% followed by almost complete release. The results confirmed the possibility of multivesicular liposomes as a long-acting or sustained-release delivery system using a combination of pegylation and encapsulation technique for controlled delivery of interferon alpha.

  13. Rheology and stability of acidified food emulsions treated with high pressure.

    PubMed

    Arora, Akshay; Chism, Grady W; Shellhammer, Thomas H

    2003-04-23

    The stability and rheology of acidified model oil-in-water emulsions (pH 3.6 +/- 0.1) were evaluated before and after high-pressure treatments. Varying concentrations of canola oil (0-50% w/w), whey protein isolate, polysorbate 60, soy lecithin (0.1-1.5% w/w each), and xanthan (0.0-0.2% w/w) were chosen. Exposure to high pressures (up to 800 MPa for 5 min at 30 degrees C) did not significantly affect the equivalent surface mean diameter D[3,2], flow behavior, and viscoelasticity of the whey protein isolate and polysorbate 60-stabilized emulsions. Pressure treatments had negligible effects on emulsion stability in these systems, except when xanthan (0.2% w/w) was present in which pressure improved the stability of polysorbate 60-stabilized emulsions. Soy lecithin-stabilized emulsions had larger mean particles sizes and lower emulsion volume indices than the others, indicating potential instability, and application of pressure further destabilized these emulsions.

  14. Swarm stability for high-order linear time-invariant singular multi-agent systems

    NASA Astrophysics Data System (ADS)

    Xi, Jianxiang; Yao, Zhicheng; Liu, Guangbin; Zhong, Yisheng

    2015-06-01

    Swarm-stability and swarm-stabilisation problems for high-order linear time-invariant singular multi-agent systems with directed networks are investigated. First, necessary and sufficient conditions for swarm stability and asymptotic swarm stability are proposed, which are independent of the dimensions of Jordan blocks of the Laplacian matrix of the interaction topology. Then, an approach is given to determine the absolute motion as a whole, and it is shown that the absolute motion is completely determined by initial states if the interaction topology is balanced. Furthermore, an approach is presented to determine gain matrices for asymptotic swarm stabilisation. Moreover, leader-following swarm-stability and swarm-stabilisation problems are investigated. Finally, numerical examples are given to demonstrate theoretical results.

  15. In-flight flow visualization with pressure measurements at low speeds on the NASA F-18 high alpha research vehicle

    NASA Technical Reports Server (NTRS)

    Delfrate, John H.; Fisher, David F.; Zuniga, Fanny A.

    1990-01-01

    In-flight results from surface and off-surface flow visualizations and from extensive pressure distributions document the vortical flow on the leading edge extensions (LEX) and forebody of the NASA F-18 high alpha research vehicle for low speeds and angles of attack up to 50 degs. Surface flow visualization data, obtained using the emitted fluid technique, were used to define separation lines and laminar separation bubbles. Off-surface flow visualization data, obtained by smoke injection, were used to document both the path of the vortex cores and the location of vortex core breakdown. The location of vortex core breakdown correlated well with the loss of suction pressure on the LEX and with the flow visualization results from ground facilities. Surface flow separation lines on the LEX and forebody corresponded well with the end of pressure recovery under the vortical flows. Correlation of the pressures with wind tunnel results show fair to good correlation.

  16. Design of a mixer for the thrust-vectoring system on the high-alpha research vehicle

    NASA Technical Reports Server (NTRS)

    Pahle, Joseph W.; Bundick, W. Thomas; Yeager, Jessie C.; Beissner, Fred L., Jr.

    1996-01-01

    One of the advanced control concepts being investigated on the High-Alpha Research Vehicle (HARV) is multi-axis thrust vectoring using an experimental thrust-vectoring (TV) system consisting of three hydraulically actuated vanes per engine. A mixer is used to translate the pitch-, roll-, and yaw-TV commands into the appropriate TV-vane commands for distribution to the vane actuators. A computer-aided optimization process was developed to perform the inversion of the thrust-vectoring effectiveness data for use by the mixer in performing this command translation. Using this process a new mixer was designed for the HARV and evaluated in simulation and flight. An important element of the Mixer is the priority logic, which determines priority among the pitch-, roll-, and yaw-TV commands.

  17. High Magnetic Shear Gain in a Liquid Sodium Stable Couette Flow Experiment: A Prelude to an {alpha}-{Omega} Dynamo

    SciTech Connect

    Colgate, Stirling A.; Beckley, Howard; Si, Jiahe; Martinic, Joe; Westpfahl, David; Slutz, James; Westrom, Cebastian; Klein, Brianna; Schendel, Paul; Scharle, Cletus; McKinney, Travis; Ginanni, Rocky; Bentley, Ian; Mickey, Timothy; Ferrel, Regnar; Li, Hui; Pariev, Vladimir; Finn, John

    2011-04-29

    The {Omega} phase of the liquid sodium {alpha}-{Omega} dynamo experiment at New Mexico Institute of Mining and Technology in cooperation with Los Alamos National Laboratory has demonstrated a high toroidal field B{sub {phi}} that is {approx_equal}8xB{sub r}, where B{sub r} is the radial component of an applied poloidal magnetic field. This enhanced toroidal field is produced by the rotational shear in stable Couette flow within liquid sodium at a magnetic Reynolds number Rm{approx_equal}120. Small turbulence in stable Taylor-Couette flow is caused by Ekman flow at the end walls, which causes an estimated turbulence energy fraction of ({delta}v/v){sup 2{approx}}10{sup -3}.

  18. Fast half-loop maneuvers for a high alpha fighter aircraft using a singular perturbation feedback control law

    NASA Technical Reports Server (NTRS)

    Garrett, Frederick E., Jr.; Stalford, Harold L.

    1989-01-01

    Singular perturbation analysis is used to derive an outer layer feedback control law for a high alpha fighter aircraft to perform the half-loop maneuver. Pitch rate and angle of attack are treated as fast variables in the derivation. Bang-bang controls are derived to transfer the aircraft state from trim to the outer layer and from the outer layer to specified final half-loop values. The pitch rate is treated as a varibale faster than the angle of attack in the transfer of the state to and from the outer layer. A simulation of the derived control law is conducted at Mach 0.6 and 15,000 feet altitude. The half-loop was performed in 13.12 seconds. It is compared with a NASA pilot simulated half-loop maneuver which took 22.42 seconds for the same initial conditions.

  19. The Different Roles of Entropy and Solubility in High Entropy Alloy Stability.

    PubMed

    Ruiz-Yi, Benjamin; Bunn, Jonathan Kenneth; Stasak, Drew; Mehta, Apurva; Besser, Matthew; Kramer, Matthew J; Takeuchi, Ichiro; Hattrick-Simpers, Jason

    2016-09-12

    Multiprincipal element high entropy alloys stabilized as a single alloy phase represent a new material system with promising properties, such as high corrosion and creep resistance, sluggish diffusion, and high temperature tensile strength. However, the mechanism of stabilization to form single phase alloys is controversial. Early studies hypothesized that a large entropy of mixing was responsible for stabilizing the single phase; more recent work has proposed that the single-phase solid solution is the result of mutual solubility of the principal elements. Here, we demonstrate the first self-consistent study of the relative importance of these two proposed mechanisms. In situ high-throughput synchrotron diffraction studies were used to monitor the stability of the single phase alloy in thin-film (Al1-x-yCuxMoy)FeNiTiVZr composition spread samples. Our results indicate that a metastable solid solution can be captured via the rapid quenching typical of physical vapor deposition processes, but upon annealing the solid-solution phase stability is primarily governed by mutual miscibility.

  20. Long-term orbital stability of exosolar planetary systems with highly eccentric orbits

    NASA Astrophysics Data System (ADS)

    Antoniadou, Kyriaki I.; Voyatzis, George

    2016-10-01

    Nowadays, many extrasolar planetary systems possessing at least one planet on a highly eccentric orbit have been discovered. In this work, we study the possible long-term stability of such systems. We consider the general three body problem as our model. Highly eccentric orbits are out of the Hill stability regions. However, mean motion resonances can provide phase protection and orbits with long-term stability exist. We construct maps of dynamical stability based on the computation of chaotic indicators and we figure out regions in phase space, where the long-term stability is guaranteed. We focus on regions where at least one planet is highly eccentric and attempt to associate them with the existence of stable periodic orbits. The values of the orbital elements, which are derived from observational data, are often given with very large deviations. Generally, phase space regions of high eccentricities are narrow and thus, our dynamical analysis may restrict considerably the valid domain of the system's location.

  1. Anticipatory attentional suppression of visual features indexed by oscillatory alpha-band power increases: a high-density electrical mapping study.

    PubMed

    Snyder, Adam C; Foxe, John J

    2010-03-17

    Retinotopically specific increases in alpha-band ( approximately 10 Hz) oscillatory power have been strongly implicated in the suppression of processing for irrelevant parts of the visual field during the deployment of visuospatial attention. Here, we asked whether this alpha suppression mechanism also plays a role in the nonspatial anticipatory biasing of feature-based attention. Visual word cues informed subjects what the task-relevant feature of an upcoming visual stimulus (S2) was, while high-density electroencephalographic recordings were acquired. We examined anticipatory oscillatory activity in the Cue-to-S2 interval ( approximately 2 s). Subjects were cued on a trial-by-trial basis to attend to either the color or direction of motion of an upcoming dot field array, and to respond when they detected that a subset of the dots differed from the majority along the target feature dimension. We used the features of color and motion, expressly because they have well known, spatially separated cortical processing areas, to distinguish shifts in alpha power over areas processing each feature. Alpha power from dorsal regions increased when motion was the irrelevant feature (i.e., color was cued), and alpha power from ventral regions increased when color was irrelevant. Thus, alpha-suppression mechanisms appear to operate during feature-based selection in much the same manner as has been shown for space-based attention.

  2. Hyperthermostable, Ca(2+)-independent, and high maltose-forming alpha-amylase production by an extreme thermophile Geobacillus thermoleovorans: whole cell immobilization.

    PubMed

    Rao, J L Uma Maheswar; Satyanarayana, T

    2009-11-01

    The synthesis of extracellular alpha-amylase in Geobacillus thermoleovorans was constitutive. The enzyme was secreted in metabolizable carbon sources as well as non-metabolizable synthetic analogues of glucose, but the titers were higher in the former than that in the latter. G. thermoleovorans is a fast-growing facultatively anaerobic bacterium that grows under both aerobic and anaerobic conditions and produces an extracellular amylolytic enzyme alpha-amylase with the by-product of lactic acid. G. thermoleovorans is a rich source of various novel thermostable biocatalysts for different industrial applications. alpha-Amylase synthesis was subject to catabolite repression in the presence of high concentrations of glucose. The addition of cAMP to the medium containing glucose did not result in the repression of alpha-amylase synthesis. The addition of maltose (1%) to the starch arginine medium resulted in a twofold enhancement in enzyme titers. Polyurethane foam (PUF)-immobilized cells secreted alpha-amylase, which was higher than that with the free cells. PUF appeared to be a better matrix for immobilization of the thermophilic bacterium than the other commonly used matrices. The repeated use of PUF-immobilized cells was possible over 15 cycles with a sustained alpha-amylase secretion. The use of this enzyme in starch saccharification eliminates the addition of Ca(2+) in starch liquefaction and its subsequent removal by ion exchangers from the product streams.

  3. alpha4beta2 nicotinic receptors with high and low acetylcholine sensitivity: pharmacology, stoichiometry, and sensitivity to long-term exposure to nicotine.

    PubMed

    Moroni, Mirko; Zwart, Ruud; Sher, Emanuele; Cassels, Bruce K; Bermudez, Isabel

    2006-08-01

    alpha4 and beta2 nicotinic acetylcholine receptor (nAChR) subunits expressed heterologously assemble into receptors with high (HS) and low (LS) sensitivity to acetylcholine (ACh); their relative proportions depend on the alpha4to beta2 ratio. In this study, injection of oocytes with 1:10 alpha4/beta2 subunit cDNA ratios favored expression of HS alpha4beta2 nAChRs, as evidenced by monophasic ACh concentration-response curves, whereas injections with 10:1 cDNA ratios favored expression of LS alpha4beta2 receptors. The stoichiometry was inferred from the shifts in the ACh EC(50) values caused by Leu to Thr mutations at position 9' of the second transmembrane domain of alpha4 and beta2. The 1:10 injection ratio produced the (alpha4)(2)(beta2)(3) stoichiometry, whereas 10:1 injections produced the (alpha4)(3)(beta2)(2) stoichiometry. The agonists epibatidine, 3-[2(S)-azetidinylmethoxy]pyridine (A-85380), 5-ethoxy-metanicotine (TC-2559), cytisine, and 3-Br-cytisine and the antagonists dihydro-beta-erythroidine and d-tubocurarine were more potent at HS receptors. TC-2559 was more efficacious than ACh at HS receptors but was a partial agonist at LS receptors. Epibatidine was more efficacious than ACh at LS receptors and a partial agonist at HS receptors. Cytisine and 5-halogenated cytisines had moderate efficacy at LS receptors but had almost no efficacy at HS receptors. By exploiting the differential effects of ACh, TC-2559 and 5-I-cytisine we evaluated the effects of long-term exposure to nicotine on HS and LS receptors expressed in Xenopus laevis oocytes after cDNA injections or microtransplantation of alpha4beta2 receptors assembled in human embryonic kidney 293 cells. We conclude that nicotine up-regulates HS alpha4beta2 receptors, probably by influencing the assembly of receptors rather than by altering the functional state of LS alpha4beta2 nAChRs.

  4. Optimum design of high speed prop rotors including the coupling of performance, aeroelastic stability and structures

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Aditi; Mccarthy, Thomas R.; Madden, John F., III

    1992-01-01

    An optimization procedure is developed for the design of high speed prop-rotors to be used in civil tiltrotor applications. The goal is to couple aerodynamic performance, aeroelastic stability, and structural design requirements inside a closed-loop optimization procedure. The objective is to minimize the gross weight and maximize the propulsive efficiency in high speed cruise. Constraints are imposed on the rotor aeroelastic stability in both hover and cruise and rotor figure of merit in hover. Both structural and aerodynamic design variables are used.

  5. HB Hillingdon [alpha46(CE4)Phe-->Val (alpha1 Or alpha2)]: a new alpha chain hemoglobin variant.

    PubMed

    Babb, Anna; Solaiman, Susannah; Green, Brian N; Mantio, Debbie; Patel, Ketan

    2009-01-01

    Routine antenatal hemoglobinopathy screening detected a new alpha chain variant that eluted with Hb A(2) on cation exchange high performance liquid chromatography (HPLC) in a lady of Sri Lankan origin who had normal hematological indices. The mutation was identified by electrospray ionization mass spectrometry (ESI-MS) as alpha46(CE4)Phe-->Val, inferring that the variant was due to a single base change at codon 46 (TTC>GTC) of the alpha1- or alpha2-globin genes.

  6. Event counting alpha detector

    DOEpatents

    Bolton, Richard D.; MacArthur, Duncan W.

    1996-01-01

    An electrostatic detector for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure.

  7. Event counting alpha detector

    DOEpatents

    Bolton, R.D.; MacArthur, D.W.

    1996-08-27

    An electrostatic detector is disclosed for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure. 6 figs.

  8. Biopolymer-stabilized Pt nanoparticles colloid: a highly active and recyclable catalyst for biphasic catalysis

    NASA Astrophysics Data System (ADS)

    Wang, Yujia; Shen, Yueyue; Qiu, Yunfei; Zhang, Ting; Liao, Yang; Zhao, Shilin; Ma, Jun; Mao, Hui

    2016-10-01

    Noble metal nanoparticles are promising candidates to replace conventional bulk counterparts owing to their high activity and selectivity. To enable catalyst recovery, noble metal nanoparticles are often supported onto solid matrices to prepare heterogeneous catalyst. Although recycle of noble metal nanoparticles is realized by heterogenization, a loss of activity is usually encountered. In the present investigation, Pt nanoparticles with tunable particle size (1.85-2.80 nm) were facilely prepared by using polyphenols as amphiphilic stabilizers. The as-prepared Pt nanoparticles colloid solution could be used as highly active catalyst in aqueous-organic biphasic catalysis. The phenolic hydroxyls of polyphenols could constrain Pt nanoparticles in aqueous phase, and simultaneously, the aromatic scaffold of polyphenols ensured effective interactions between substrates and Pt nanoparticles. As a consequence, the obtained polyphenols-stabilized Pt nanoparticles exhibited high activity and cycling stability in biphasic hydrogenation of a series of unsaturated compounds. Compared with conventional heterogeneous Pt-C and Pt-Al2O3 catalysts, polyphenols-stabilized Pt nanoparticles showed obvious advantage both in activity and cycling stability.

  9. Geophysical analysis of the Alpha-Mendeleev ridge complex: Characterization of the High Arctic Large Igneous Province

    NASA Astrophysics Data System (ADS)

    Oakey, G. N.; Saltus, R. W.

    2016-11-01

    The Alpha-Mendeleev ridge complex is a first-order physiographic and geological feature of the Arctic Amerasia Basin. High amplitude "chaotic" magnetic anomalies (the High Arctic Magnetic High Domain or HAMH) are associated with the complex and extend beyond the bathymetric high beneath the sediment cover of the adjacent Canada and Makarov-Podvodnikov basins. Residual marine Bouguer gravity anomalies over the ridge complex have low amplitudes implying that the structure has minimal lateral density variability. A closed pseudogravity (magnetic potential) contour around the ridge complex quantifies the aerial extent of the HAMH at 1.3 × 106 km2. We present 2D gravity/magnetic models for transects across the Alpha Ridge portion of the complex constrained with recently acquired seismic reflection and refraction data. The crustal structure is modeled with a simple three-layer geometry. Large induced and remanent magnetization components were required to fit the observed magnetic anomalies. Density values for the models were based on available seismic refraction P-wave velocities. The 3000 kg/m3 lower crustal layer is interpreted as a composite of the original crustal protolith and deep (ultramafic) plutonic intrusions related to a plume sourced (High Arctic) LIP. The 2900 kg/m3 mid-crustal and 2600 kg/m3 upper-crustal layers are interpreted as the combined effect of sills, dikes, and flows. Volumetric estimates of the volcanic composition include (at least) 6 × 106 km3 for the mid- and upper-crust and between 13 × 106 and 17 × 106 km3 within the lower crust - for a total of 20 × 106 km3. We compare the magnetic structure, pseudogravity, and volumetric estimates for the HAMH portion of the HALIP with global large igneous province analogs and discuss implications for Arctic tectonics. Our results show that the closest analog to the HAMH/HALIP is the Kerguelen Plateau, which is considered a continental plateau intensively modified by plume-related volcanism.

  10. Obsidian provenance determination using the beam stability controlled BSC-XRF and the PIXE-alpha portable spectrometers of the LANDIS laboratory: the case of the Via Capuana settlement in Licodia Eubea (Sicily)

    NASA Astrophysics Data System (ADS)

    Pappalardo, L.; Romano, F. P.; Bracchitta, D.; Massimino, A.; Palio, O.; Rizzo, F.

    2013-12-01

    In the last decade about 800 obsidian artifacts coming from various archaeological sites of Sicily have been analyzed using the BSC-XRF (beam stability controlled-x-ray fluorescence) and PIXE-alpha (particle induced x-ray emission, using low-energy alpha particles) portable spectrometers developed at the Landis laboratory of the LNS-INFN and IBAM-CNR in Catania (Italy). The portable BSC-XRF system allows the non-destructive analysis of Rb, Sr, Y, Zr and Nb trace concentrations, which are considered to be characteristic of the obsidian samples and consequently are indicative of the provenance quarries. Quantitative data on the above trace-element concentrations were deduced using a method that makes use of a multi-parameter linear regression. The portable PIXE-alpha spectrometer allows the quantitative determination of the matrix major elements, from Na to Zn. In this paper the updated versions of the instrumental devices and methods are presented together with a review of all the obtained data from various Sicilian sites. Results on compositional data for trace elements and major elements allowed us to identify Lipari and Pantelleria islands as the only two sources of the analyzed samples. Recent data about the Via Capuana settlement in Licodia Eubea are also presented and discussed for the first time.

  11. Obsidian provenance determination by using the beam stability controlled BSC-XRF and the PIXE-alpha portable spectrometers of the LANDIS laboratory of the LNS-INFN and IBAM-CNR in Catania (Italy)

    NASA Astrophysics Data System (ADS)

    Pappalardo, L.; Bracchitta, D.; Palio, O.; Pappalardo, G.; Rizzo, F.

    2012-04-01

    About 1300 obsidian artefacts coming from various archaeological sites of Sicily were analyzed by using the BSC-XRF (Beam Stability Controlled - X-ray Fluorescence) and PIXE-alpha (Particle Induced X-ray Emission, using low energy alpha particles) portable spectrometers developed at the Landis laboratory at the LNS-INF and IBAM-CNR in Catania (Italy). The portable BSC-XRF system allows the non-destructive analysis of the Rb, Sr, Y, Zr and Nb trace concentrations, which are considered to be characteristic of the obsidian samples and consequently are indicative of the provenance quarries. Quantitative data on Rb, Sr, Y, Zr, Nb trace element concentrations where deduced through the use of a method that makes use of a multi parameter linear regression, previously The portable PIXE-alpha spectrometer allows the quantitative determination of the matrix major elements, from Na to Zn. In the present work the two instrumental devices are presented. The data are from: Milena (Cl), Ustica (Pa), Rocchicella (Ct), Poggio dell'Acquila (Ct), San Marco (Ct), Villaggio del Petraro* (Sr) and Licodia Eubea* (Ct). Results on compositional data for trace elements and major elements allowed to identify Lipari and Pantelleria islands as the only two sources of the analysed samples. Analyses carried out on vitreous artefact found in Rocchicella, showed for the first time that the Palagonite was used as row material. *Preliminary data. Topic of conference: Application of XRS in archaeometry Kind of presentation: oral

  12. Serous ovarian carcinoma patients with high alpha-folate receptor had reducing survival and cytotoxic chemo-response.

    PubMed

    Chen, Yu-Li; Chang, Ming-Cheng; Huang, Chia-Yen; Chiang, Ying-Cheng; Lin, Han-Wei; Chen, Chi-An; Hsieh, Chang-Yao; Cheng, Wen-Fang

    2012-06-01

    The alpha-folate receptor (α-FR) is highly-expressed in various non-mucinous tumors of epithelial origin, including ovarian carcinoma. The aim of this study was to investigate the relationship between alpha-folate receptor (α-FR) and the clinico-pathologic features and outcomes of serous ovarian carcinoma patients and the possible mechanism of α-FR to chemo-resistance. Therefore, semi-quantitative reverse-transcription polymerase chain reactions for α-FR expression were performed in the 91 specimens of serous ovarian carcinomas. The expression of α-FR in each ovarian cancer tissue specimen was defined as the ratio of density of α-FR to density of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In vitro apoptotic experiments were tested in the original OVCAR-3 tumor cells and various OVCAR-3 α-FR-transfectants. Patients with an increased α-FR expression level had poorer responses to chemotherapy (per α-FR expression level increase: odds ratio (OR): 8.97 (95% confidence interval (CI): 1.40-57.36), p = 0.021). An increased α-FR expression level was an independently poor prognostic factor for disease free interval (DFI) (per α-FR expression level increase: hazard ratio (HR): 2.45 (95% CI: 1.16-5.18), p = 0.02) and had a negative impact on overall survival (OS) of these serous ovarian cancer patients (per α-FR expression level increase: HR: 3.6 (95% CI: 0.93-13.29), p = 0.03) by multivariate analyses. α-FR inhibited cytotoxic drug-induced apoptosis in our in vitro apoptotic assays. α-FR could induce chemo-resistance via regulating the expression of apoptosis-related molecules, Bcl-2 and Bax. Therefore, α-FR can be a potential biomarker for the prediction of chemotherapeutic responses and clinical prognosis. It also could be the target of ovarian cancer treatment.

  13. Design aspects of a solar array drive for spot, with a high platform stability objective

    NASA Technical Reports Server (NTRS)

    Cabillic, J.; Fournier, J. P.; Anstett, P.; Souliac, M.; Thomin, G.

    1981-01-01

    A solar array drive mechanism (MEGS) for the SPOT platform, which is a prototype of a multimission platform, is described. High-resolution cameras and other optical instruments are carried by the platform, requiring excellent platform stability in order to obtain high-quality pictures. Therefore, a severe requirement for the MEGS is the low level of disturbing torques it may generate considering the 0.6 times 10 to the minus 3 power deg/sec stability required. The mechanical design aspects aiming at reducing the mean friction torque, and therefore its fluctuations, are described as well as the method of compensation of the motor imperfections. It was concluded, however, that this is not sufficient to reach the stability requirement.

  14. Identification of sorghum hybrids with high phenotypic stability using GGE biplot methodology.

    PubMed

    Teodoro, P E; Almeida Filho, J E; Daher, R F; Menezes, C B; Cardoso, M J; Godinho, V P C; Torres, F E; Tardin, F D

    2016-06-10

    The aim of this study was to identify sorghum hybrids that have both high yield and phenotypic stability in Brazilian environments. Seven trials were conducted between February and March 2011. The experimental design was a randomized complete block with 25 treatments and three replicates. The treatments consisted of 20 simple pre-commercial hybrids and five witnesses of grain sorghum. Sorghum genotypes were analyzed by the genotype main effects + genotype environment interaction (GGE) biplot method if significant genotype x environment interaction, adaptability, and phenotypic stability were detected. GGE biplot methodology identified two groups of environments, the first composed of Água Comprida-MG, Montividiu-GO, and Vilhena- RO and the second of Guaíra-SP and Sete Lagoas-MG. The BRS 308 and 1G282 genotypes were found to have high grain yield, adaptability, and phenotypic stability and are thus indicated for cultivation in the first and second groups of environments, respectively.

  15. Phase stabilization of VO{sub 2} thin films in high vacuum

    SciTech Connect

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

    2015-11-14

    A new growth approach to stabilize VO{sub 2} on Al{sub 2}O{sub 3} 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 VO{sub 2} 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 V{sub 2}O{sub 3} phase. Careful optimization of growth temperature, VTIP to V ratio, and growth rate led to high quality single phase VO{sub 2} 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.

  16. Characterization of radicals and high-molecular weight species from alpha-pinene/ozone reaction and ambient aerosol samples

    NASA Astrophysics Data System (ADS)

    Pavlovic, Jelica

    Secondary organic aerosol formed during oxidation of different volatile organic compounds is composed from a number of final and intermediate reaction products. The final products include compounds in both low and high molecular weight range called also oligomer species. These compounds can be highly volatile, as well as being semi- or low-volatility compounds. This study characterized intermediate reactive radical products formed from previously often studied alpha-pinene/ozone reaction. In order to passivate those radical species nitrone spin traps were used. 5,5-dimethyl-4,5-dihydro-3H-pyrrole-N-oxide (DMPO), and 5-dietoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) traps were able to successfully trap oxygen- and carbon-centered radicals produced from alpha-pinene/ozone reaction. Electrospray ionization (ESI) in negative ion mode with mass spectrometry (MS) detection was used to scan spectra of formed spin trap adducts and the tandem mass spectrometry (MSn) to elucidate its structures as well as structures of captured radicals. The same method was applied to analyze radical species present in ambient PM2.5 samples. Few carbon- (alkyl) and oxygen- (alkoxyl) centered radicals were captured with DMPO and DEPMPO traps. The second part of this study was focused on high molecular weight (high-MW) species formed from the same reaction (alpha-pinene/ozone), but found also in fine particulate matter fractions of ambient samples. LC/MS/MS analysis of dimer species from chamber study revealed fragments that can originate from peroxide structures. Proposed reaction for these peroxide dimer formation is self reaction of two peroxyl radicals, followed by the loss of oxygen molecule. These findings emphasize the role of peroxyl (ROO) radicals in formation of high-MW products and are in line with the high O:C ratio results reported in other studies. Water soluble organic carbon (WSOC) extracts of three size fractions of the ambient aerosol, PM1--2.5, PM0.1--1, and PM<0

  17. Regulation of hepatic branched-chain alpha-keto acid dehydrogenase complex in rats fed a high-fat diet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: Branched-chain alpha-keto acid dehydrogenase complex (BCKDC) regulates branched-chain amino acid (BCAA) metabolism at the level of branched chain alpha-ketoacid (BCKA) catabolism. It has been demonstrated that the activity of hepatic BCKDC is markedly decreased in type 2 diabetic animal...

  18. Development of an Apparatus for Wind Tunnel Dynamic Experiments at High-alpha

    NASA Technical Reports Server (NTRS)

    Pedreiro, Nelson

    1997-01-01

    A unique experimental apparatus that allows a wind tunnel model two degrees of freedom has been designed and built. The apparatus was developed to investigate the use of new methods to augment aircraft control in the high angle of attack regime. The model support system provides a platform in which the roll-yaw coupling at high angles of attack can be studied in a controlled environment. Active cancellation of external effects is used to provide a system in which the dynamics are dominated by the aerodynamic loads acting on the wind tunnel model.

  19. High K-alpha X-ray Conversion Efficiency From Extended Source Gas Jet Targets Irradiated by Ultra Short Laser Pulses

    SciTech Connect

    Kugland, N L; Constantin, C; Collette, A; Dewald, E; Froula, D; Glenzer, S H; Kritcher, A; Neumayer, P; Ross, J S; Niemann, C

    2007-11-01

    The absolute laser conversion efficiency to K{sub {alpha}}-like inner shell x-rays (integrated from K{sub {alpha}} to K{sub {beta}}) is observed to be an order of magnitude higher in argon gas jets than in solid targets due to enhanced emission from higher ionization stages following ultra short pulse laser irradiation. Excluding the higher ionization stages, the conversion efficiency to near-cold K{sub {alpha}} is the same in gas jets as in solid targets. These results demonstrate that gas jet targets are bright, high conversion efficiency, high repetition rate, debris-free multi-keV x-ray sources for spectrally resolved scattering and backlighting of rapidly evolving dense matter.

  20. Internal kink stabilization by high-energy ions with nonstandard orbits

    NASA Astrophysics Data System (ADS)

    Porcelli, F.; Stankiewicz, R.; Berk, H. L.; Zhang, Y. Z.

    1992-10-01

    A generalized energy principle that takes into account the nonstandard, potato-shaped particle orbits of high-energy ions in the central region of a tokamak is derived. It is shown that, in the limit of zero orbit width, this energy principle reduces to the one formulated by Van Dam et al. [Phys. Fluids 25, 1349 (1982)]. The modification of hot particle stabilization theory when such orbit effects are important is investigated. In particular, a model distribution function is chosen to describe high-energy trapped ions produced by ion cyclotron resonant frequency (ICRF) heating applied near the axis of a tokamak. Standard banana orbit theory predicts that, for fixed total stored energy of energetic particles peaked about the magnetic axis, the stabilizing influence on internal kink modes is inversely proportional to the spatial spread of the hot particles. However, this scaling saturates when the spatial spread of the distribution function approaches the width of a typical nonstandard orbit. Hence, ICRF heating is most efficient in producing stabilization when the heating zone is comparable to the orbit width, while the tendency to stabilize does not improve if the heating zone is narrower than the orbit width. Further, it is shown that, if particle orbits can extend close to the q=1 surface, the tendency for stabilization is inhibited.

  1. RESISTIVE WALL STABILIZATION OF HIGH BETA PLASMAS IN DIII-D

    SciTech Connect

    STRAIT,EJ; BIALEK,J; BOGATU,N; CHANCE,M; CHU,MS; EDGELL,D; GAROFALO,AM; JACKSON,GL; JENSEN,TH; JOHNSON,LC; KIM,JS; LAHAYE,RJ; NAVRATIL,G; OKABAYASHI,M; REIMERDES,H; SCOVILLE,JT; TURNBULL,AD; WALKER,ML

    2002-09-01

    OAK A271 RESISTIVE WALL STABILIZATION OF HIGH BETA PLASMAS IN DIII-D. Recent DIII-D experiments show that ideal kink modes can be stabilized at high beta by a resistive wall, with sufficient plasma rotation. However, the resonant response by a marginally stable resistive wall mode to static magnetic field asymmetries can lead to strong damping of the rotation. Careful reduction of such asymmetries has allowed plasmas with beta well above the ideal MHD no-wall limit, and approaching the ideal-wall limit, to be sustained for durations exceeding one second. Feedback control can improve plasma stability by direct stabilization of the resistive wall mode or by reducing magnetic field asymmetry. Assisted by plasma rotation, direct feedback control of resistive wall modes with growth rates more than 5 times faster than the characteristic wall time has been observed. These results open a new regime of tokamak operation above the free-boundary stability limit, accessible by a combination of plasma rotation and feedback control.

  2. Elongated fibrillar structure of a streptococcal adhesin assembled by the high-affinity association of [alpha]- and PPII-helices

    SciTech Connect

    Larson, Matthew R.; Rajashankar, Kanagalaghatta R.; Patel, Manisha H.; Robinette, Rebekah A.; Crowley, Paula J.; Michalek, Suzanne; Brady, L. Jeannine; Deivanayagam, Champion

    2010-08-18

    Streptococcus mutans antigen I/II (AgI/II) is a cell surface-localized protein adhesin that interacts with salivary components within the salivary pellicle. AgI/II contributes to virulence and has been studied as an immunological and structural target, but a fundamental understanding of its underlying architecture has been lacking. Here we report a high-resolution (1.8 {angstrom}) crystal structure of the A{sub 3}VP{sub 1} fragment of S. mutans AgI/II that demonstrates a unique fibrillar form (155 {angstrom}) through the interaction of two noncontiguous regions in the primary sequence. The A{sub 3} repeat of the alanine-rich domain adopts an extended {alpha}-helix that intertwines with the P{sub 1} repeat polyproline type II (PPII) helix to form a highly extended stalk-like structure heretofore unseen in prokaryotic or eukaryotic protein structures. Velocity sedimentation studies indicate that full-length AgI/II that contains three A/P repeats extends over 50 nanometers in length. Isothermal titration calorimetry revealed that the high-affinity association between the A{sub 3} and P{sub 1} helices is enthalpically driven. Two distinct binding sites on AgI/II to the host receptor salivary agglutinin (SAG) were identified by surface plasmon resonance (SPR). The current crystal structure reveals that AgI/II family proteins are extended fibrillar structures with the number of alanine- and proline-rich repeats determining their length.

  3. Rates of processing of the high mannose oligosaccharide units at the three glycosylation sites of mouse thyrotropin and the two sites of free alpha-subunits

    SciTech Connect

    Miura, Y.; Perkel, V.S.; Magner, J.A.

    1988-09-01

    We have determined the structures of high mannose (Man) oligosaccharide units at individual glycosylation sites of mouse TSH. Mouse thyrotropic tumor tissue was incubated with D-(2-/sup 3/H)Man with or without (/sup 14/C)tyrosine ((/sup 14/C) Tyr) for 2, 3, or 6 h, and for a 3-h pulse followed by a 2-h chase. TSH heterodimers or free alpha-subunits were obtained from homogenates using specific antisera. After reduction and alkylation, subunits were treated with trypsin. The tryptic fragments were then loaded on a reverse phase HPLC column to separate tryptic fragments bearing labeled oligosaccharides. The N-linked oligosaccharides were released with endoglycosidase-H and analyzed by paper chromatography. Man9GlcNac2 and Man8GlcNac2 units predominated at each time point and at each specific glycosylation site, but the processing of high Man oligosaccharides differed at each glycosylation site. The processing at Asn23 of TSH beta-subunits was slower than that at Asn56 or Asn82 of alpha-subunits. The processing at Asn82 was slightly faster than that at Asn56 for both alpha-subunits of TSH heterodimers and free alpha-subunits. The present study demonstrates that the early processing of oligosaccharides differs at the individual glycosylation sites of TSH and free alpha-subunits, perhaps because of local conformational differences.

  4. Neuronal acetylcholine receptors in Drosophila: the ARD protein is a component of a high-affinity alpha-bungarotoxin binding complex.

    PubMed Central

    Schloss, P; Hermans-Borgmeyer, I; Betz, H; Gundelfinger, E D

    1988-01-01

    The ard gene of Drosophila melanogaster encodes a structural homologue of vertebrate nicotinic acetylcholine receptors (AChR) and is expressed exclusively in nervous tissue. To study the nature of the ARD protein, antibodies were raised against fusion constructs containing two regions of this polypeptide. One segment is putatively extracellular (amino acids 65-212), the other domain is exposed to the cytoplasm (amino acids 305-444). The ARD antisera obtained served to investigate the physical relationship between the ARD protein and alpha-bungarotoxin (alpha-Btx) binding sites occurring in Drosophila. Two different high-affinity binding sites for [125I]alpha-Btx, a highly potent antagonist of vertebrate muscle AChR, were detected in fly head membranes. Equilibrium binding and kinetic studies revealed Kd values of approximately 0.1 nM (site 1) and approximately 4 nM (site 2). The estimated maximal binding (Bmax) was approximately 240 and 1080 fmol/mg protein respectively. Both sites exhibited a nicotinic-cholinergic pharmacology. Immunoprecipitation experiments with the ARD antisera indicated that the ARD protein is associated with the [125I]alpha-Btx binding site 1 only. These data support the previously postulated hypothesis that the ARD protein is part of an alpha-Btx binding neuronal AChR of Drosophila. Furthermore, they indicate heterogeneity in nicotinic-cholinergic binding sites in the insect nervous system. PMID:3141150

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Classical swine fever (CSF) is an economically significant, highly contagious swine disease. The etiological agent, CSF virus (CSFV), is an enveloped virus with a positive-sense, single-stranded RNA genome, classified as a member of the genus Pestivirus within the family Flaviviridae (Becher et al.,...

  6. Aromatic poly(arylene ether urea) with high dipole moment for high thermal stability and high energy density capacitors

    NASA Astrophysics Data System (ADS)

    Cheng, Zhaoxi; Lin, Minren; Wu, Shan; Thakur, Yash; Zhou, Yue; Jeong, Dae-Yong; Shen, Qundong; Zhang, Q. M.

    2015-05-01

    Developing dielectric polymers with higher dielectric constant without sacrificing loss and thermal stability is of great importance for next generation of high energy density capacitors. We show here that by replacing the CH2 group in the aromatic polyurea (ArPU) with the polar ether group, thus raising the dipole moment of the molecular unit, poly(arylene ether urea) (PEEU) shows an increased dielectric constant of 4.7, compared with 4.2 of ArPU. Moreover, PEEU maintains the low dielectric loss and is thermally stable up to 250 °C. As a result, the polymer delivers 13 J/cm3 discharged energy density at room temperature and 9 J/cm3 at 120 °C. The high quality films perform well in terms of both breakdown strength (at 700 MV/m at room temperature) and leakage current from room temperature to elevated temperature. At 120 °C, the breakdown strength is 600 MV/m and the conductivity is 1.58 × 10-14 S/cm measured under 100 MV/m.

  7. Comparing high density LIDAR and medium resolution GPS generated elevation data for predicting yield stability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High density light detection and ranging (LIDAR) imaging has been shown to be able to define yield stability areas of a field for multi-cropping. Since LIDAR imaging is expensive and not widely available, we hypothesized that medium resolution GPS elevation data which is commonly collected with var...

  8. High-temperature stabilization by air of a pyrophoric catalyst for the synthesis of ammonia

    SciTech Connect

    Krylova, A.V.; Ustimenko, G.A.

    1982-12-01

    The reaction of a catalyst for the synthesis of ammonia with air at 480 to 520/sup 0/C leads to the formation on the surface of a thin protective oxide structure that eliminates its pyrophoric character. High-temperature stabilization by air is a considerably faster process than passivation and leads to the production of catalysts with increased resistance to oxidation.

  9. Enhancing Economic Stability Utilizing the High Technologies in Community Colleges: A Case Study.

    ERIC Educational Resources Information Center

    Mehnert, Barbara H.; Kurki, Allan W.

    Strategies to enhance the economic stability of community colleges through high technology approaches are discussed in this paper. First, general economic problems facing higher education are identified, and the ways in which they influence community colleges are described. Next, 10 strategies to aid in the economic recovery of community colleges…

  10. High-level waste-form-product performance evaluation. [Leaching; waste loading; mechanical stability

    SciTech Connect

    Bernadzikowski, T A; Allender, J S; Stone, J A; Gordon, D E; Gould, Jr, T H; Westberry, III, C F

    1982-01-01

    Seven candidate waste forms were evaluated for immobilization and geologic disposal of high-level radioactive wastes. The waste forms were compared on the basis of leach resistance, mechanical stability, and waste loading. All forms performed well at leaching temperatures of 40, 90, and 150/sup 0/C. Ceramic forms ranked highest, followed by glasses, a metal matrix form, and concrete. 11 tables.

  11. Polydopamine tethered enzyme/metal-organic framework composites with high stability and reusability.

    PubMed

    Wu, Xiaoling; Yang, Cheng; Ge, Jun; Liu, Zheng

    2015-12-07

    An enzyme/metal-organic framework (MOF) composite with both highly stable and easily reusable features was prepared via tethering enzyme/MOF nanocrystals with polydopamine (PDA). The micrometer-sized PDA tethered enzyme/MOF composite can be easily repeatedly used without obvious activity loss, promising for efficient enzymatic catalysis at low cost with long-term operational stability under harsh conditions.

  12. Cylindrical dye-sensitized solar cells with high efficiency and stability over time and incident angle.

    PubMed

    Tang, Qunwei; Zhang, Lei; He, Benlin; Yu, Liangmin; Yang, Peizhi

    2016-02-28

    We present here the realization of cylindrical dye-sensitized solar cells composed of Ti wire supported TiO2 nanotube anodes and transparent metal selenide counter electrodes. The optimized device yields a high efficiency of 6.63%, good stability over time, and identical efficiency output at arbitrary incident angles.

  13. Novel, electrolyte solutions comprising fully inorganic salts with high anodic stability for rechargeable magnesium batteries

    SciTech Connect

    Doe, RE; Han, R; Hwang, J; Gmitter, AJ; Shterenberg, I; Yoo, HD; Pour, N; Aurbach, D

    2014-01-01

    Herein the first inorganic magnesium salt solution capable of highly reversible magnesium electrodeposition is presented. Synthesized by acid-base reaction of MgCl2 and Lewis acidic compounds such as AlCl3, this salt class demonstrates upwards of 99% Coulombic efficiency, deposition overpotential of <200 mV, and anodic stability of 3.1 V.

  14. High alpha-tomatine content in ripe fruit of Andean Lycopersicon esculentum var. cerasiforme: developmental and genetic aspects.

    PubMed Central

    Rick, C M; Uhlig, J W; Jones, A D

    1994-01-01

    A variant of Lycopersion esculentum var. cerasiforme is described that deviates from the typical form of the entire species, including cultivated tomatoes, in possessing high levels (500-5000 micrograms/g of dry weight) of the steroidal alkaloid alpha-tomatine in its ripe fruits. This biotype is restricted to a tiny enclave in the valley of Río Mayo, Department San Martín, Peru. Among 88 accessions of var. cerasiforme from its present distribution in the Andes, a 90% association was found between high tomatine and bitter flavor; within the Mayo watershed, all samples from the upper drainage had bitterness and high tomatine; the frequency of both traits decreased to low levels toward the lower end. Tomatine therefore probably is the source of bitterness. Throughout L. esculentum tomatine is present at very high concentrations in earliest stages of fruit development, thereafter decreasing rapidly to midperiod, and finally diminishing gradually to near zero at maturity as a result of catabolism to biologically inert compounds, except in the variant described here. High tomatine content does not appear to affect adversely either the natives, among whom the bitter types are popular, or individuals who sampled them in this survey. Genetic determination of high tomatine in ripe fruits is totally recessive and appears to be monogenic with interaction with genes of minor effect. The prevailing pattern of glycoalkaloid synthesis and degradation in development of solanaceous fruits suggests a mechanism to protect against predation prior to ripening but to permit it afterward as a device to promote dispersal. In consideration of the nondegradative nature of the variant, its genetic determination, and very restricted geographic distribution, mutation to this form appears to be a random event of doubtful evolutionary significance. PMID:7809139

  15. High alpha-tomatine content in ripe fruit of Andean Lycopersicon esculentum var. cerasiforme: developmental and genetic aspects.

    PubMed

    Rick, C M; Uhlig, J W; Jones, A D

    1994-12-20

    A variant of Lycopersion esculentum var. cerasiforme is described that deviates from the typical form of the entire species, including cultivated tomatoes, in possessing high levels (500-5000 micrograms/g of dry weight) of the steroidal alkaloid alpha-tomatine in its ripe fruits. This biotype is restricted to a tiny enclave in the valley of Río Mayo, Department San Martín, Peru. Among 88 accessions of var. cerasiforme from its present distribution in the Andes, a 90% association was found between high tomatine and bitter flavor; within the Mayo watershed, all samples from the upper drainage had bitterness and high tomatine; the frequency of both traits decreased to low levels toward the lower end. Tomatine therefore probably is the source of bitterness. Throughout L. esculentum tomatine is present at very high concentrations in earliest stages of fruit development, thereafter decreasing rapidly to midperiod, and finally diminishing gradually to near zero at maturity as a result of catabolism to biologically inert compounds, except in the variant described here. High tomatine content does not appear to affect adversely either the natives, among whom the bitter types are popular, or individuals who sampled them in this survey. Genetic determination of high tomatine in ripe fruits is totally recessive and appears to be monogenic with interaction with genes of minor effect. The prevailing pattern of glycoalkaloid synthesis and degradation in development of solanaceous fruits suggests a mechanism to protect against predation prior to ripening but to permit it afterward as a device to promote dispersal. In consideration of the nondegradative nature of the variant, its genetic determination, and very restricted geographic distribution, mutation to this form appears to be a random event of doubtful evolutionary significance.

  16. Application of variable-gain output feedback for high-alpha control

    NASA Technical Reports Server (NTRS)

    Ostroff, Aaron J.

    1990-01-01

    A variable-gain, optimal, discrete, output feedback design approach that is applied to a nonlinear flight regime is described. The flight regime covers a wide angle-of-attack range that includes stall and post stall. The paper includes brief descriptions of the variable-gain formulation, the discrete-control structure and flight equations used to apply the design approach, and the high performance airplane model used in the application. Both linear and nonlinear analysis are shown for a longitudinal four-model design case with angles of attack of 5, 15, 35, and 60 deg. Linear and nonlinear simulations are compared for a single-point longitudinal design at 60 deg angle of attack. Nonlinear simulations for the four-model, multi-mode, variable-gain design include a longitudinal pitch-up and pitch-down maneuver and high angle-of-attack regulation during a lateral maneuver.

  17. Titanium compounds as catalysts of higher alpha-olefin-based super-high-molecular polymers synthesis

    NASA Astrophysics Data System (ADS)

    Konovalov, K. B.; Kazaryan, M. A.; Manzhay, V. N.; Vetrova, O. V.

    2016-01-01

    The synthesis of polymers of 10 million or more molecular weight is a difficult task even in a chemical lab. Higher α-olefin-based polymer agents of such kind have found a narrow but quite important niche, the reduction of drag in the turbulent flow of hydrocarbon fluids such as oil and oil-products. In its turn, searching for a catalytic system capable to produce molecules of such a high length and to synthesize polymers of a low molecular-mass distribution is part of a global task of obtaining a high-quality product. In this paper we had observed a number of industrial catalysts with respect to their suitability for higher poly-α- olefins synthesis. A number samples representing copolymers of 1-hexene with 1-decene obtained on a previous generation catalyst, a microsphere titanium chloride catalytic agent had been compared to samples synthesized using a titanium-magnesium catalyst both in solution and in a polymer medium.

  18. Investigation of High Temperature Ductility Losses in Alpha-Beta Titanium Alloys

    DTIC Science & Technology

    1988-04-01

    0 diffractometer was used, so the best extrapolation parameter was cos/ine. Based on this: Ad/d = cos e/ s ine Starting with Bragg’s law , nX = 2dsinB...Naval Research Laboratory Materials Science & Component Technology WahngoDC 20375-5000 D TICV ELECTE ____________JUNit 16 Ei oi April, 1988 S - AQ...colony microconstituent S and ductility was found to exist only at high temperature, indicating that the deformation characteristics of the material

  19. The Orbital Design of Alpha Centauri Exoplanet Satellite (ACESat)

    NASA Technical Reports Server (NTRS)

    Weston, Sasha; Belikov, Rus; Bendek, Eduardo

    2015-01-01

    Exoplanet candidates discovered by Kepler are too distant for biomarkers to be detected with foreseeable technology. Alpha Centauri has high separation from other stars and is of close proximity to Earth, which makes the binary star system 'low hanging fruit' for scientists. Alpha Centauri Exoplanet Satellite (ACESat) is a mission proposed to Small Explorer Program (SMEX) that will use a coronagraph to search for an orbiting planet around one of the stars of Alpha Centauri. The trajectory design for this mission is presented here where three different trajectories are considered: Low Earth Orbit (LEO), Geosynchronous Orbit (GEO) and a Heliocentric Orbit. Uninterrupted stare time to Alpha Centauri is desirable for meeting science requirements, or an orbit that provides 90% stare time to the science target. The instrument thermal stability also has stringent requirements for proper function, influencing trajectory design.

  20. Analogs of alpha-melanocyte stimulating hormone with high agonist potency and selectivity at human melanocortin receptor 1b: the role of Trp(9) in molecular recognition.

    PubMed

    Bednarek, Maria A; Macneil, Tanya; Tang, Rui; Fong, Tung M; Angeles Cabello, M; Maroto, Marta; Teran, Ana

    2008-05-01

    alpha-Melanocyte stimulating hormone (alphaMSH), Ac-Ser(1)-Tyr(2)-Ser(3)-Met(4)-Glu(5)-His(6)-Phe(7)-Arg(8)-Trp(9)-Gly(10)-Lys(11)-Pro(12)-Val(13)-NH(2), is an endogenous agonist for the melanocortin receptor 1 (MC1R), the receptor found in the skin, several types of immune cells, and other peripheral sites. Three-dimensional models of complexes of this receptor with alphaMSH and its synthetic analog NDP-alphaMSH, Ac-Ser(1)-Tyr(2)-Ser(3)-Nle(4)-Glu(5)-His(6)-D-Phe(7)-Arg(8)-Trp(9)-Gly(10)-Lys(11)-Pro(12)-Val(13)-NH(2), have been previously proposed. In those models, the 6-9 segment of the ligand was considered essential for the ligand-receptor interactions. In this study, we probed the role of Trp(9) of NDP-alphaMSH in interactions with hMC1bR. Analogs of NDP-alphaMSH with various amino acids in place of Trp(9) were synthesized and tested in vitro in receptor affinity binding and cAMP functional assays at human melanocortin receptors 1b, 3, 4, and 5 (hMC1b,3-5R). Several new compounds displayed high agonist potency at hMC1bR (EC(50) = 0.5-5 nM) and receptor subtype selectivity greater than 2000-fold versus hMC3-5R. The Trp(9) residue of NDP-alphaMSH was determined to be not essential for molecular recognition at hMC1bR.

  1. High-precision {sup 28}Si(p,t){sup 26}Si reaction to determine {sup 22}Mg({alpha},p){sup 25}Al reaction rates

    SciTech Connect

    Matic, A.; Berg, A. M. van den; Harakeh, M. N.; Woertche, H. J.; Beard, M.; Berg, G. P. A.; Goerres, J.; LeBlanc, P.; O'Brien, S.; Wiescher, M.; Fujita, K.; Hatanaka, K.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Tamii, A.; Yosoi, M.; Adachi, T.; Fujita, Y.; Shimbara, Y.

    2011-08-15

    The rise time of stellar x-ray bursts is a signature of thermonuclear runaway processes in the atmosphere of neutron stars and is highly sensitive to a series of ({alpha},p) reactions via high-lying resonances in sd-shell nuclei. Lacking data for the relevant resonance levels, the stellar reaction rates have been calculated using statistical, Hauser-Feshbach models, assuming a high-level density. This assumption may not be correct in view of the selectivity of the ({alpha},p) reaction to natural parity states. We measured the {sup 28}Si(p,t){sup 26}Si reaction with a high-resolution spectrometer to identify resonance levels in {sup 26}Si above the {alpha}-emission threshold at 9.164 MeV excitation energy. These resonance levels are used to calculate the stellar reaction rate of the {sup 22}Mg({alpha},p){sup 25}Al reaction and to test the validity of the statistical assumption.

  2. High-bandwidth transfer of phase stability through a fiber frequency comb.

    PubMed

    Scharnhorst, Nils; Wübbena, Jannes B; Hannig, Stephan; Jakobsen, Kornelius; Kramer, Johannes; Leroux, Ian D; Schmidt, Piet O

    2015-07-27

    We demonstrate phase locking of a 729 nm diode laser to a 1542 nm master laser via an erbium-doped-fiber frequency comb, using a transfer-oscillator feedforward scheme which suppresses the effect of comb noise in an unprecedented 1.8 MHz bandwidth. We illustrate its performance by carrying out coherent manipulations of a trapped calcium ion with 99 % fidelity even at few-μs timescales. We thus demonstrate that transfer-oscillator locking can provide sufficient phase stability for high-fidelity quantum logic manipulation even without pre-stabilization of the slave diode laser.

  3. Space applications of superconductivity - Resonators for high stability oscillators and other applications

    NASA Technical Reports Server (NTRS)

    Stein, S. R.

    1980-01-01

    The potential applications of superconductivity in space are examined. It is shown that superconducting oscillators have achieved better frequency stability that any other device for averaging times of 10 s to 1000 s. Such a high stability results from the use of solid niobium resonators having Q factors greater that 10 to the 10th. Oscillators of this type have direct applications as clocks and spectrally pure sources. In addition, they may also be used for accurate measurements of many physical quantities and to perform a variety of experiments on fundamental constants, relativity, and gravity waves.

  4. Limiter stabilization of high-beta external kink-tearing modes

    SciTech Connect

    Lee, J.K.; Ohyabu, N.

    1984-12-01

    The stabilizing effects of finite-width poloidal limiters, toroidal limiters, and general mushroom limiters are examined for high-beta finite resistivity tokamak plamas in free boundary. When the plasma pressure and resistivity are small, a poloidal limiter is effective in reducing the growth rate even with a small limiter size, while a toroidal limiter requires a large size for a comparable effect. As the plasma pressure or resistivity increases, a toroidal limiter becomes more effective in reducing the growth rate than a poloidal limiter of the same size. A small optimized mushroom limiter might have a stabilizing effect similar to a conducting shell.

  5. High-temperature earth-storable propellant acoustic cavity technology. [for combustion stability

    NASA Technical Reports Server (NTRS)

    Oberg, C. L.; Hines, W. S.; Falk, A. Y.

    1974-01-01

    Design criteria, methods and data, were developed to permit effective design of acoustic cavities for use in regeneratively cooled OME-type engines. This information was developed experimentally from two series of motor firings with high-temperature fuel during which the engine stability was evaluated under various conditions and with various cavity configurations. Supplementary analyses and acoustic model testing were used to aid cavity design and interpretation of results. Results from this program clearly indicate that dynamic stability in regeneratively cooled OME-type engines can be ensured through the use of acoustic cavities. Moreover, multiple modes of instability were successfully suppressed with the cavity.

  6. High-stability Finite-Length Silicon Nanowires: A Real Space Theoretical Study

    NASA Astrophysics Data System (ADS)

    Koukaras, E. N.; Zdetsis, A. D.; Garoufalis, C. S.

    2007-12-01

    We demonstrate by real-space density functional calculations that unreconstructed low-stability finite size hydrogenated silicon nanowires could bend through relaxation under the influence of internal strains, contrary to high-stability "magic" nanowires. The strains and the resulting bending depend on the distribution and orientation of silicon dihydrides on the nanowire's surface. This and other related effects cannot be accounted for by the usual k-space supercell techniques. We also demonstrate that reconstructed (2×1) nanowires, although bend they are practically as stable as the "magic" unreconstructed nanowires. Our calculations are in full agreement with the experimental work of Ma et al. [Science 299, 1874, (2003)].

  7. In vivo wear performance of highly cross-linked polyethylene vs. yttria stabilized zirconia and alumina stabilized zirconia at a mean seven-year follow-up

    PubMed Central

    2013-01-01

    Background Zirconia was introduced as an alternative to alumina for use in the femoral head. The yttria stabilized zirconia material was improved by adding alumina. We evaluated highly cross-linked polyethylene wear performance of zirconia in total hip arthroplasty. The hypothesis was that alumina stabilized zirconia could decrease highly cross-linked polyethylene wear. Methods Highly cross-linked polyethylene wear was measured with a computerized method (PolyWare) in 91 hips. The steady-state wear rates were measured based on the radiographs from the first year postoperatively to the final follow-up and were compared between hips with yttria stabilized zirconia and alumina stabilized zirconia. Results The steady-state wear rate of highly cross-linked polyethylene against zirconia was 0.02 mm/year at a mean follow-up of 7 years. No significant difference was observed between groups with yttria stabilized zirconia and alumina stabilized zirconia. Conclusions Addition of alumina to the zirconia material failed to show further reduction of highly cross-linked polyethylene wear and our hypothesis was not verified. PMID:23634809

  8. Stability of rhombohedral phases in vanadium at high-pressure and high-temperature: first-principles investigations

    NASA Astrophysics Data System (ADS)

    Wang, Yi X.; Wu, Q.; Chen, Xiang R.; Geng, Hua Y.

    2016-09-01

    The pressure-induced transition of vanadium from BCC to rhombohedral structures is unique and intriguing among transition metals. In this work, the stability of these phases is revisited by using density functional theory. At finite temperatures, a novel transition of rhombohedral phases back to BCC phase induced by thermal electrons is discovered. This reentrant transition is found not driven by phonons, instead it is the electronic entropy that stabilizes the latter phase, which is totally out of expectation. Parallel to this transition, we find a peculiar and strong increase of the shear modulus C44 with increasing temperature. It is counter-intuitive in the sense that it suggests an unusual harding mechanism of vanadium by temperature. With these stability analyses, the high-pressure and finite-temperature phase diagram of vanadium is proposed. Furthermore, the dependence of the stability of RH phases on the Fermi energy and chemical environment is investigated. The results demonstrate that the position of the Fermi level has a significant impact on the phase stability, and follows the band-filling argument. Besides the Fermi surface nesting, we find that the localization/delocalization of the d orbitals also contributes to the instability of rhombohedral distortions in vanadium.

  9. Stability of rhombohedral phases in vanadium at high-pressure and high-temperature: first-principles investigations

    PubMed Central

    Wang, Yi X.; Wu, Q.; Chen, Xiang R.; Geng, Hua Y.

    2016-01-01

    The pressure-induced transition of vanadium from BCC to rhombohedral structures is unique and intriguing among transition metals. In this work, the stability of these phases is revisited by using density functional theory. At finite temperatures, a novel transition of rhombohedral phases back to BCC phase induced by thermal electrons is discovered. This reentrant transition is found not driven by phonons, instead it is the electronic entropy that stabilizes the latter phase, which is totally out of expectation. Parallel to this transition, we find a peculiar and strong increase of the shear modulus C44 with increasing temperature. It is counter-intuitive in the sense that it suggests an unusual harding mechanism of vanadium by temperature. With these stability analyses, the high-pressure and finite-temperature phase diagram of vanadium is proposed. Furthermore, the dependence of the stability of RH phases on the Fermi energy and chemical environment is investigated. The results demonstrate that the position of the Fermi level has a significant impact on the phase stability, and follows the band-filling argument. Besides the Fermi surface nesting, we find that the localization/delocalization of the d orbitals also contributes to the instability of rhombohedral distortions in vanadium. PMID:27581551

  10. Active Resistive Wall Mode Stabilization in Low Rotation, High Beta NSTX Plasmas

    NASA Astrophysics Data System (ADS)

    Sabbagh, S. A.

    2006-10-01

    An active feedback system to stabilize the resistive wall mode (RWM) in the National Spherical Torus Experiment (NSTX) is used to maintain plasma stability for greater than 90 RWM growth times. These experiments are the first to demonstrate RWM active stabilization in high beta, low aspect ratio tokamak plasmas with toroidal plasma rotation significantly below the critical rotation profile for passive stability and in the range predicted for ITER. Actively stabilized, low rotation plasmas reached normalized beta of 5.6, and the ratio of normalized beta to the toroidal mode number, n = 1 and 2 ideal no-wall stability limits reached 1.2 and 1.15 respectively, determined by DCON stability analysis of the time-evolving reconstructed experimental equilibria. The significant, controlled reduction of the plasma rotation to less than one percent of the Alfven speed was produced by non-resonant magnetic braking by an applied n = 3 field. The observed plasma rotation damping is in quantitative agreement with neoclassical toroidal viscosity theory including trapped particle effects [1]. The active stabilization system employs a mode control algorithm using RWM sensor input analyzed to distinguish the amplitude and phase of the n = 1 mode. During n = 1 stabilization, the n = 2 mode amplitude increases and surpasses the n = 1 amplitude, but the mode remains stable. By varying the system gain, and relative phase between the measured n = 1 RWM phase and the applied control field, both positive and negative feedback were demonstrated. Contrary to past experience in moderate aspect ratio tokamaks with poloidally continuous stabilizing structure, the RWM can become unstable in certain cases by deforming poloidally, an important consideration for feedback system sensor and control coil design in future devices such as ITER and KSTAR. **In collaboration with R.E. Bell, J.E. Menard, D.A. Gates, A.C. Sontag, J.M. Bialek, B.P. LeBlanc, F.M. Levinton, K. Tritz, H. Yuh. [1] W. Zhu, S

  11. A novel high pressure, high temperature vessel used to conduct long-term stability measurements of silicon MEMS pressure transducers

    NASA Astrophysics Data System (ADS)

    Wisniewiski, David

    2014-03-01

    The need to quantify and to improve long-term stability of pressure transducers is a persistent requirement from the aerospace sector. Specifically, the incorporation of real-time pressure monitoring in aircraft landing gear, as exemplified in Tire Pressure Monitoring Systems (TPMS), has placed greater demand on the pressure transducer for improved performance and increased reliability which is manifested in low lifecycle cost and minimal maintenance downtime through fuel savings and increased life of the tire. Piezoresistive (PR) silicon MEMS pressure transducers are the primary choice as a transduction method for this measurement owing to their ability to be designed for the harsh environment seen in aircraft landing gear. However, these pressure transducers are only as valuable as the long-term stability they possess to ensure reliable, real-time monitoring over tens of years. The "heart" of the pressure transducer is the silicon MEMS element, and it is at this basic level where the long-term stability is established and needs to be quantified. A novel High Pressure, High Temperature (HPHT) vessel has been designed and constructed to facilitate this critical measurement of the silicon MEMS element directly through a process of mechanically "floating" the silicon MEMS element while being subjected to the extreme environments of pressure and temperature, simultaneously. Furthermore, the HPHT vessel is scalable to permit up to fifty specimens to be tested at one time to provide a statistically significant data population on which to draw reasonable conclusions on long-term stability. With the knowledge gained on the silicon MEMS element, higher level assembly to the pressure transducer envelope package can also be quantified as to the build-effects contribution to long-term stability in the same HPHT vessel due to its accommodating size. Accordingly, a HPHT vessel offering multiple levels of configurability and robustness in data measurement is presented, along

  12. OXYGEN ABUNDANCES IN LOW- AND HIGH-{alpha} FIELD HALO STARS AND THE DISCOVERY OF TWO FIELD STARS BORN IN GLOBULAR CLUSTERS

    SciTech Connect

    Ramirez, I.; Melendez, J.

    2012-10-01

    Oxygen abundances of 67 dwarf stars in the metallicity range -1.6 < [Fe/H] < -0.4 are derived from a non-LTE analysis of the 777 nm O I triplet lines. These stars have precise atmospheric parameters measured by Nissen and Schuster, who find that they separate into three groups based on their kinematics and {alpha}-element (Mg, Si, Ca, Ti) abundances: thick disk, high-{alpha} halo, and low-{alpha} halo. We find the oxygen abundance trends of thick-disk and high-{alpha} halo stars very similar. The low-{alpha} stars show a larger star-to-star scatter in [O/Fe] at a given [Fe/H] and have systematically lower oxygen abundances compared to the other two groups. Thus, we find the behavior of oxygen abundances in these groups of stars similar to that of the {alpha} elements. We use previously published oxygen abundance data of disk and very metal-poor halo stars to present an overall view (-2.3 < [Fe/H] < +0.3) of oxygen abundance trends of stars in the solar neighborhood. Two field halo dwarf stars stand out in their O and Na abundances. Both G53-41 and G150-40 have very low oxygen and very high sodium abundances, which are key signatures of the abundance anomalies observed in globular cluster (GC) stars. Therefore, they are likely field halo stars born in GCs. If true, we estimate that at least 3% {+-} 2% of the local field metal-poor star population was born in GCs.

  13. Computational analysis of forebody tangential slot blowing on the high alpha research vehicle

    NASA Technical Reports Server (NTRS)

    Gee, Ken

    1994-01-01

    Current and future fighter aircraft can maneuver in the high-angle-of-attack flight regime while flying at low subsonic and transonic freestream Mach numbers. However, at any flight speed, the ability of the vertical tails to generate yawing moment is limited in high-angle-of-attack flight. Thus, any system designed to provide the pilot with additional side force and yawing moment must work in both low subsonic and transonic flight. However, previous investigations of the effectiveness of forebody tangential slot blowing in generating the desired control forces and moments have been limited to the low subsonic freestream flow regime. In order to investigate the effectiveness of tangential slot blowing in transonic flight, a computational fluid dynamics analysis was carried out during the grant period. Computational solutions were obtained at three different freestream Mach numbers and at various jet mass flow ratios. All results were obtained using the isolated F/A-18 forebody grid geometry at 30.3 degrees angle of attack. One goal of the research was to determine the effect of freestream Mach number on the effectiveness of forebody tangential slot blowing in generating yawing moment. The second part of the research studied the force onset time lag associated with blowing. The time required for the yawing moment to reach a steady-state value from the onset of blowing may have an impact on the implementation of a pneumatic system on a flight vehicle.

  14. Enhanced efficacy of an AAV vector encoding chimeric, highly secreted acid alpha-glucosidase in glycogen storage disease type II.

    PubMed

    Sun, Baodong; Zhang, Haoyue; Benjamin, Daniel K; Brown, Talmage; Bird, Andrew; Young, Sarah P; McVie-Wylie, Alison; Chen, Y-T; Koeberl, Dwight D

    2006-12-01

    Glycogen storage disease type II (GSD-II; Pompe disease; MIM 232300) is an inherited muscular dystrophy caused by deficiency in the activity of the lysosomal enzyme acid alpha-glucosidase (GAA). We hypothesized that chimeric GAA containing an alternative signal peptide could increase the secretion of GAA from transduced cells and enhance the receptor-mediated uptake of GAA in striated muscle. The relative secretion of chimeric GAA from transfected 293 cells increased up to 26-fold. Receptor-mediated uptake of secreted, chimeric GAA corrected cultured GSD-II patient cells. High-level hGAA was sustained in the plasma of GSD-II mice for 24 weeks following administration of an AAV2/8 vector encoding chimeric GAA; furthermore, GAA activity was increased and glycogen content was significantly reduced in striated muscle and in the brain. Administration of only 1 x 10(10) vector particles increased GAA activity in the heart and diaphragm for >18 weeks, whereas 3 x 10(10) vector particles increased GAA activity and reduced glycogen content in the heart, diaphragm, and quadriceps. Furthermore, an AAV2/2 vector encoding chimeric GAA produced secreted hGAA for >12 weeks in the majority of treated GSD-II mice. Thus, chimeric, highly secreted GAA enhanced the efficacy of AAV vector-mediated gene therapy in GSD-II mice.

  15. Targeted Biomarker Discovery by High Throughput Glycosylation Profiling of Human Plasma Alpha1-Antitrypsin and Immunoglobulin A

    PubMed Central

    Ruhaak, L. Renee; Koeleman, Carolien A. M.; Uh, Hae-Won; Stam, Jord C.; van Heemst, Diana; Maier, Andrea B.; Houwing-Duistermaat, Jeanine J.; Hensbergen, Paul J.; Slagboom, P. Eline; Deelder, André M.; Wuhrer, Manfred

    2013-01-01

    Protein N-glycosylation patterns are known to show vast genetic as well as physiological and pathological variation and represent a large pool of potential biomarkers. Large-scale studies are needed for the identification and validation of biomarkers, and the analytical techniques required have recently been developed. Such methods have up to now mainly been applied to complex mixtures of glycoproteins in biofluids (e.g. plasma). Here, we analyzed N-glycosylation profiles of alpha1-antitrypsin (AAT) and immunoglobulin A (IgA) enriched fractions by 96-well microtitration plate based high-throughput immuno-affinity capturing and N-glycan analysis using multiplexed capillary gel electrophoresis with laser-induced fluorescence detection (CGE-LIF). Human plasma samples were from the Leiden Longevity Study comprising 2415 participants of different chronological and biological ages. Glycosylation patterns of AAT enriched fractions were found to be associated with chronological (calendar) age and they differed between females and males. Moreover, several glycans in the AAT enriched fraction were associated with physiological parameters marking cardiovascular and metabolic diseases. Pronounced differences were found between males and females in the glycosylation profiles of IgA enriched fractions. Our results demonstrate that large-scale immuno-affinity capturing of proteins from human plasma using a bead-based method combined with high-throughput N-glycan analysis is a powerful tool for the discovery of glycosylation-based biomarker candidates. PMID:24039863

  16. The protective effect of alpha lipoic acid on Schwann cells exposed to constant or intermittent high glucose.

    PubMed

    Sun, Lian-Qing; Chen, Ying-Ying; Wang, Xuan; Li, Xiao-Jin; Xue, Bing; Qu, Ling; Zhang, Ting-Ting; Mu, Yi-Ming; Lu, Ju-Ming

    2012-10-01

    Diabetic peripheral neuropathy (DPN) is one of the most common and costly microvascular complications of diabetes, and no effective therapy exists. Previous studies have demonstrated that oxidative stress may be the unifying factor for the damaging effect of hyperglycemia. The aim of this study was to examine the impact of treatment with Alpha lipoic acid (ALA) on the intermittent high glucose (IHG) or high glucose (HG)-induced oxidative stress-induced mitochondrial pathway activation and Schwann cells (SCs) apoptosis in vitro. Our results suggested that IHG and HG induced SCs apoptosis in both caspase-dependent and caspase-independent pathways related to oxidative stress. More importantly, the cytotoxic effect of IHG was significantly more potent than that of HG. Treatment with ALA inhibited the IHG and HG-induced oxidative stress and apoptosis in SCs. Furthermore, treatment with ALA down-regulated the Bax expression and the release of cytochrome c and AIF translocation, but up-regulated the Bcl-2 expression in SCs. Treatment with ALA attenuated the activation of caspase-3 and caspase-9 and minimized the cleavage of PARP in SCs. These findings suggest that variability in glycemic control could be more deleterious than a constant HG and ALA antagonized the IHG-induced oxidative stress, activation of mitochondrial pathway and apoptosis in SCs.

  17. Orbital stability of coplanar two-planet exosystems with high eccentricities

    NASA Astrophysics Data System (ADS)

    Antoniadou, Kyriaki I.; Voyatzis, George

    2016-10-01

    The long-term stability of the evolution of two-planet systems is considered by using the general three body problem (GTBP). Our study is focused on the stability of systems with adjacent orbits when at least one of them is highly eccentric. In these cases, in order for close encounters, which destabilize the planetary systems, to be avoided, phase protection mechanisms should be considered. Additionally, since the GTBP is a non-integrable system, chaos may also cause the destabilization of the system after a long time interval. By computing dynamical maps, based on Fast Lyapunov Indicator, we reveal regions in phase space with stable orbits even for very high eccentricities (e > 0.5). Such regions are present in mean motion resonances (MMRs). We can determine the position of the exact MMR through the computation of families of periodic orbits in a rotating frame. Elliptic periodic orbits are associated with the presence of apsidal corotation resonances (ACRs). When such solutions are stable, they are associated with neighbouring domains of initial conditions that provide long-term stability. We apply our methodology so that the evolution of planetary systems of highly eccentric orbits is assigned to the existence of such stable domains. Particularly, we study the orbital evolution of the extrasolar systems HD 82943, HD 3651, HD 7449, HD 89744 and HD 102272 and discuss the consistency between the orbital elements provided by the observations and the dynamical stability.

  18. Efficient one-step radiolabeling of monoclonal antibodies to high specific activity with Actinium-225 for alpha-particle radioimmunotherapy of cancer

    PubMed Central

    Maguire, William F.; McDevitt, Michael R.; Smith-Jones, Peter M.; Scheinberg, David A.

    2015-01-01

    Targeted alpha-particle radiation using the radioisotope 225Actinium (225Ac) is a promising form of therapy for various types of cancer. Historical obstacles to the use of 225Ac have been the difficulty in finding suitable chelators to stably attach it to targeting vehicles such as peptides and monoclonal antibodies, the low specific activities of the products, and the lack of cost-effective radiolabeling procedures. We initially solved the first problem with a procedure involving two chemical steps that has been used as a standard in preclinical and clinical studies. However, this procedure involves the loss of 90% of the input 225Ac. A more efficient, economical process is needed to facilitate the more widespread use of 225Ac. Methods We conjugated representative antibodies with two forms of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), as well as other chelators as controls. We developed conditions to radiolabel these constructs in one chemical step and characterized their stability, immunoreactivity, biodistribution, and therapeutic efficacy in healthy and tumor-bearing mice. Results DOTA- antibody constructs were labeled to a wide range of specific activities in one chemical step at 37 °C. Radiochemical yields were approximately 10-fold higher and specific activities were up to 30-fold higher than with the previous approach. The products retained immunoreactivity and were stable to serum challenge in vitro and in mice. Labeling kinetics of DOTA- antibody constructs linked through a benzyl isothiocyanate linkage were more favorable than those linked through a N-hydroxysuccinimide linkage. Tissue distribution was similar but not identical between the constructs. The constructs produced specific therapeutic responses in a mouse model of acute myeloid leukemia. Conclusion We have characterized an efficient, one-step radiolabeling method that produces stable, therapeutically active conjugates of antibodies with 225Ac at high specific activity

  19. Transient Stability of the US Western Interconnection with High Wind and Solar Generation

    SciTech Connect

    Clark, Kara; Miller, Nicholas W.; Shao, Miaolei; Pajic, Slobodan; D'Aquila, Robert

    2015-07-03

    The addition of large amounts of wind and solar generation to bulk power systems that are traditionally subject to operating constraints set by transient limitations is the subject of considerable concern in the industry. The US Western Interconnection (WI) is expected to experience substantial additional growth in both wind and solar generation. These plants will, to some extent, displace large central station thermal generation, both coal and gas-fired, which have traditionally helped maintain stability. This paper reports the results of a study that investigated the transient stability of the WI with high penetrations of wind and solar generation. The main goals of this work were to (1) create a realistic, baseline model of the WI, (2) test selected transient stability events, (3) investigate the impact of large amounts of wind and solar generation, and (4) examine means to improve performance.

  20. Stabilized chip-scale Kerr frequency comb via a high-Q reference photonic microresonator

    NASA Astrophysics Data System (ADS)

    Lim, Jinkang; Huang, Shu-Wei; Vinod, Abhinav K.; Mortazavian, Parastou; Yu, Mingbin; Kwong, Dim-Lee; Savchenkov, Anatoliy A.; Matsko, Andrey B.; Maleki, Lute; Wong, Chee Wei

    2016-08-01

    We stabilize a chip-scale Si3N4 phase-locked Kerr frequency comb via locking the pump laser to an independent stable high-Q reference microresonator and locking the comb spacing to an external microwave oscillator. In this comb, the pump laser shift induces negligible impact on the comb spacing change. This scheme is a step towards miniaturization of the stabilized Kerr comb system as the microresonator reference can potentially be integrated on-chip. Fractional instability of the optical harmonics of the stabilized comb is limited by the microwave oscillator used for comb spacing lock below 1 s averaging time and coincides with the pump laser drift in the long term.

  1. Stabilized chip-scale Kerr frequency comb via a high-Q reference photonic microresonator.

    PubMed

    Lim, Jinkang; Huang, Shu-Wei; Vinod, Abhinav K; Mortazavian, Parastou; Yu, Mingbin; Kwong, Dim-Lee; Savchenkov, Anatoliy A; Matsko, Andrey B; Maleki, Lute; Wong, Chee Wei

    2016-08-15

    We stabilize a chip-scale Si3N4 phase-locked Kerr frequency comb via locking the pump laser to an independent stable high-Q reference microresonator and locking the comb spacing to an external microwave oscillator. In this comb, the pump laser shift induces negligible impact on the comb spacing change. This scheme is a step toward miniaturization of the stabilized Kerr comb system as the microresonator reference can potentially be integrated on-chip. Fractional instability of the optical harmonics of the stabilized comb is limited by the microwave oscillator used for a comb spacing lock below 1 s averaging time and coincides with the pump laser drift in the long term.

  2. High pressure stability of protein complexes studied by static and dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Gebhardt, Ronald; Kulozik, Ulrich

    2011-03-01

    The high pressure dissociation of hemocyanin prepared from the lobster Homarus americanus and casein micelles from cow milk were observed by in situ light scattering. The hemocyanin dodecamer dissociated via a hexamer into monomers in a two-step three-species reaction. The influence of ligands and the effector l-lactate on the dissociation behavior was investigated. While no effect by carbon monoxide after exchanging the ligand oxygen was observed, the addition of the effector l-lactate led to a decrease in the pressure stability. Due to a trimer intermediate which was found to be stabilized by l-lactate, the dissociation reaction in the presence of the effector was analyzed by a three-step four-species reaction. In the case of casein micelles, a two-step dissociation mechanism was found. The stabilizing interactions of casein micelles were identified and separated.

  3. Understanding phase stability of Al-Co-Cr-Fe-Ni high entropy alloys

    SciTech Connect

    Zhang, Chuan; Zhang, Fan; Diao, Haoyan; Gao, Michael C.; Tang, Zhi; Poplawsky, Jonathan D.; Liaw, Peter K.

    2016-07-19

    The concept of high entropy alloy (HEA) opens a vast unexplored composition range for alloy design. As a well-studied system, Al-Co-Cr-Fe-Ni has attracted tremendous amount of attention to develop new-generation low-density structural materials for automobile and aerospace applications. In spite of intensive investigations in the past few years, the phase stability within this HEA system is still poorly understood and needs to be clarified, which poses obstacles to the discovery of promising Al-Co-Cr-Fe-Ni HEAs. In the present work, the CALPHAD approach is employed to understand the phase stability and explore the phase transformation within the Al-Co-Cr-Fe-Ni system. As a result, the phase-stability mapping coupled with density contours is then constructed within the composition - temperature space, which provides useful guidelines for the design of low-density Al-Co-Cr-Fe-Ni HEAs with desirable properties.

  4. High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability

    PubMed Central

    Yang, Weihuang; Li, Jinchai; Zhang, Yong; Huang, Po-Kai; Lu, Tien-Chang; Kuo, Hao-Chung; Li, Shuping; Yang, Xu; Chen, Hangyang; Liu, Dayi; Kang, Junyong

    2014-01-01

    High internal efficiency and high temperature stability ultraviolet (UV) light-emitting diodes (LEDs) at 308 nm were achieved using high density (2.5 × 109 cm−2) GaN/AlN quantum dots (QDs) grown by MOVPE. Photoluminescence shows the characteristic behaviors of QDs: nearly constant linewidth and emission energy, and linear dependence of the intensity with varying excitation power. More significantly, the radiative recombination was found to dominant from 15 to 300 K, with a high internal quantum efficiency of 62% even at room temperature. PMID:24898569

  5. Silica Cladding of Ag Nanoparticles for High Stability and Surface-Enhanced Raman Spectroscopy Performance

    NASA Astrophysics Data System (ADS)

    Zhao, Miaomiao; Guo, Hao; Liu, Wenyao; Tang, Jun; Wang, Lei; Zhang, Binzhen; Xue, Chenyang; Liu, Jun; Zhang, Wendong

    2016-09-01

    For high-precision biochemical sensing, surface-enhanced Raman spectroscopy (SERS) has been demonstrated to be a highly sensitive spectroscopic analytical method and Ag is considered to be the best material for SERS performance. Due to the high surface activity of Ag nanoparticles, the high stability of Ag nanostructures, especially in moist environments, is one of the key issues that need to be solved. A method for silica (SiO2) cladding of Ag nanoparticles (NPs) is demonstrated here for high sensitivity and long-term stability when putted in aqueous solution. The chemically inert, transparent, hydrophilic, and bio-compatible SiO2 surface acts as the protection layer for the Ag nanoparticles, which can also enhance the Raman intensity to a certain extent. In our study, the Ag@SiO2 core-shell substrate can detect crystal violet solutions with molar concentrations down to 10-12 M. After 24 h of immersion, the reduction in Raman scattering intensity is about 85 % for sole Ag NP films, compared to 12 % for the Ag coated with a 10-nm SiO2 layer. This thickness was found to be optimum for Ag@SiO2 core-shell substrates with long-term stability and high SERS activity.

  6. Multi-temporal database of High Resolution Stereo Camera (HRSC) images - Alpha version

    NASA Astrophysics Data System (ADS)

    Erkeling, G.; Luesebrink, D.; Hiesinger, H.; Reiss, D.; Jaumann, R.

    2014-04-01

    Image data transmitted to Earth by Martian spacecraft since the 1970s, for example by Mariner and Viking, Mars Global Surveyor (MGS), Mars Express (MEx) and the Mars Reconnaissance Orbiter (MRO) showed, that the surface of Mars has changed dramatically and actually is continually changing [e.g., 1-8]. The changes are attributed to a large variety of atmospherical, geological and morphological processes, including eolian processes [9,10], mass wasting processes [11], changes of the polar caps [12] and impact cratering processes [13]. In addition, comparisons between Mariner, Viking and Mars Global Surveyor images suggest that more than one third of the Martian surface has brightened or darkened by at least 10% [6]. Albedo changes can have effects on the global heat balance and the circulation of winds, which can result in further surface changes [14-15]. The High Resolution Stereo Camera (HRSC) [16,17] on board Mars Express (MEx) covers large areas at high resolution and is therefore suited to detect the frequency, extent and origin of Martian surface changes. Since 2003 HRSC acquires highresolution images of the Martian surface and contributes to Martian research, with focus on the surface morphology, the geology and mineralogy, the role of liquid water on the surface and in the atmosphere, on volcanism, as well as on the proposed climate change throughout the Martian history and has improved our understanding of the evolution of Mars significantly [18-21]. The HRSC data are available at ESA's Planetary Science Archive (PSA) as well as through the NASA Planetary Data System (PDS). Both data platforms are frequently used by the scientific community and provide additional software and environments to further generate map-projected and geometrically calibrated HRSC data. However, while previews of the images are available, there is no possibility to quickly and conveniently see the spatial and temporal availability of HRSC images in a specific region, which is

  7. Predictors of the stability of high entropy alloys: is the entropy of mixing sufficient?

    NASA Astrophysics Data System (ADS)

    Troparevsky, M. Claudia; Morris, James R.; Kent, Paul; Stocks, G. Malcolm

    2014-03-01

    High entropy alloys (HEAs) have attracted extensive attention due to their remarkable combination of strength, ductility, thermal stability, corrosion and wear resistance. However, little is known about why these alloys are stable in a single-phase solid solution or how to predict which combinations of elements will form a single phase HEA. Here, we present density functional theory calculations of the heat of formation of several HEAs in an effort to assess the role of the entropy of mixing in the stability of these alloys. The systems studied here include both single-phase and multi-phase alloys. The heats of formation show no significant differences, regardless of their single or multi phase formation, and no trends that could explain the stability of the single phase materials. Moreover, all of the calculated heats of formation are positive. These findings indicate that the entropy of mixing is insufficient to explain the unique stability of these alloys, and highlights the need for new criteria to explain the formation of single-phase solid solutions. We also discuss the minimum energy structures of several FCC and BCC alloys as well as their relative phase stability. Primarily supported by MSED.

  8. Stability of High-Jc Nb3Sn Wires in the Adiabatic Limit

    SciTech Connect

    Ghosh, A.; Gregory, E.; Peng, X.

    2011-08-03

    High-J{sub c} Nb{sub 3}Sn strands often exhibit instabilities in 4.2 K liquid helium at low fields {approx} 0.5 to 3 T which are associated with magnetization flux-jumps. However at 1.9 K in superfluid helium, a minimum in premature quench currents at intermediate fields of 5 to 7 T has been observed in voltage-current measurements. These measurements are typically used for critical current determinations, and the premature quenching is driven by current redistribution within the strand as the current is increased and is termed 'self-field' instability. In this paper, the magnetization and self-field stability of Nb{sub 3}Sn strands with J{sub c} {approx} 2000 A/mm{sup 2} at 12 T are described for a series of wires made using the Sn-tube approach with filament diameters ranging from 13 to 65 {mu}m. The copper stabilizer of these wires after reaction has residual resistivity ratio, RRR, of {approx}5, which in effect means that any dynamic stabilization from thermal conduction effects is negligible. In this regime of RRR, we find that the magnetization stability with transport current increases with decreasing filament diameter as predicted by simple adiabatic theory. We also observed that at 4.2 K the self-field stability improved with decreasing filament size, but became worse with decreasing temperature as seen in measurements at 2.0 K.

  9. Prevalence of -alpha(3.7) and alpha alpha alpha(anti3.7) alleles in sickle cell trait and beta-thalassemia patients in Mexico.

    PubMed

    Nava, María Paulina; Ibarra, Bertha; Magaña, María Teresa; de la Luz Chávez, María; Perea, F Javier

    2006-01-01

    The aim of this study was to determine the frequency of alpha-globin gene mutations in three groups of Mexican unrelated individuals. The first two groups were normal and sickle cell trait individuals from the Costa Chica region, a place with a 12.8% frequency of HbS carriers, and the third group comprised of Mexican mestizo patients with beta-thalassemia. We searched for -alpha(3.7) and -alpha(4.2) alpha(+)-thalassemia deletion alleles, as well as the alpha alpha alpha(anti3.7) triplication through long-gap PCR. The alleles -alpha(3.7) and alpha alpha alpha(anti3.7) were found in the heterozygote state only; 19% of the normal subjects had the -alpha(3.7) allele, and 2% showed the alpha alpha alpha(anti3.7) allele. In individuals with the sickle cell trait, 17% had the -alpha(3.7) deletion, and the alpha alpha alpha(anti3.7) triplication was observed in 3% of these individuals. We revealed that 16% of the subjects with beta-thalassemia showed the -alpha(3.7) deletion and 28% the alpha alpha alpha(anti3.7) triplication. The -alpha(4.2) deletion was not detected in any individual. The frequency of the -alpha(3.7) allele was roughly the same in the three groups studied; this can be explained by the fact that the three groups have common genes from Africa and the Mediterranean, where a high prevalence of alpha(+)-thalassemia has been observed. To our knowledge, the frequency of alpha alpha alpha(anti3.7) triplication observed in the Mexican beta-thalassemia patients is the highest reported. As the -alpha(3.7) and alpha alpha alpha(anti3.7) alleles are very common in our selected populations, we believe that there is a need to investigate systematically the alpha-globin gene mutations in all hemoglobinopathies in the Mexican population.

  10. Effect of low-energy alpha-particles irradiation on surface structure and physical-mechanical properties of high-purity tungsten

    NASA Astrophysics Data System (ADS)

    Aldabergenova, T. M.; Kislitsin, S. B.; Larionov, A. S.; Yar-Mukhamedova, G. S.

    2016-11-01

    Effect of radiation by low-energy alpha-particles on the surface structure and physical-mechanical properties of high-purity tungsten was studied. Samples of tungsten were irradiated by 4He+2 ions with the energy of 45 keV at low-energy channel of accelerator DC-60 in Astana branch of Institute Nuclear Physics. Irradiation fluence was 1.5 × 1018 cm-2, irradiation temperature was 150°C. Experimentally found that irradiation with low-energy alpha particles results in formation of helium filled bubbles in the straggling region.

  11. Development of a cell-based assay for measurement of c-Met phosphorylation using AlphaScreen technology and high-content imaging analysis.

    PubMed

    Smotrov, Nadya; Mathur, Anjili; Kariv, Ilona; Moxham, Christopher M; Bays, Nathan

    2009-04-01

    c-Met is a receptor tyrosine kinase (RTK) with a critical role in many fundamental cellular processes, including cell proliferation and differentiation. Deregulated c-Met signaling has been implicated in both the initiation and progression of human cancers and therefore represents an attractive target for anticancer therapy. Monitoring the phosphorylation status of relevant tyrosine residues provides an important method of assessing c-Met kinase activity. This report describes a novel assay to monitor c-Met phosphorylation in cells using Amplified Luminescent Proximity Homogeneous Assay (AlphaScreen) technology. Using AlphaScreen, the authors were able to detect both global and site-specific phosphorylation of c-Met in transformed cell lines. Data obtained from the AlphaScreen assay were compared to data obtained from a high-content imaging (HCI) method developed in parallel to monitor c-Met phosphorylation at the single cell level. The AlphaScreen assay was miniaturized to a 384-well format with acceptable signal-to-background ratio (S/B) and Z' statistics and was employed to measure c-Met kinase activity in situ after treatment with potent c-Met-specific kinase inhibitors. The authors discuss the utility of quantifying endogenous cellular c-Met phosphorylation in lead optimization and how the modular design of the AlphaScreen assay allows its adaptation to measure cellular activity of other kinases.

  12. Enhancing the High Temperature Capability of Nanocrystalline Alloys: Utilizing Thermodynamic Stability Maps to Mitigate Grain Growth Through Solute Selection

    DTIC Science & Technology

    2013-12-01

    Army Research Laboratory Enhancing the High Temperature Capability of Nanocrystalline Alloys : Utilizing Thermodynamic Stability Maps to Mitigate...Laboratory Aberdeen Proving Ground, MD 21005 ARL-TR-6743 December 2013 Enhancing the High Temperature Capability of Nanocrystalline Alloys : Utilizing...Final Enhancing the High Temperature Capability of Nanocrystalline Alloys : Utilizing Thermodynamic Stability Maps to Mitigate Grain Growth Through

  13. Evaluation of the high temperature texture of the [Beta] phase of a TA6V sample from the individual orientations of grains of the low temperature [alpha] phase

    SciTech Connect

    Humbert, M.; Moustahfid, H.; Wagner, F.; Philippe, M.J. )

    1994-02-01

    The texture of the low temperature state is an important state is an important parameter, which is greatly involved in the plastic deformation of polycrystals. In this schema, the first step is to determine the texture of the high temperature state, using various high temperature processes. Unfortunately, the direct determination of the texture of the high temperature phase is not easy and sometimes impossible. This contribution describes an indirect method of determination of this [beta] texture, based on the fact that a grain of the high temperature [beta] phase transforms into different [alpha] plates during the phase transformation, where the [alpha] plate orientation is correlated with the orientation of the former [beta] grain. The determination of the orientation of the parent [beta] grain is possible, provided that the boundaries of the parent [beta] grain are clear, the number of different plate orientations sufficient, and that a strict orientation relation between the [alpha] and [beta] lattices exists. Using this method, the authors have obtained the texture of the [beta] phase of an alloy of TA6V from the determination of the orientations of a population of parent [beta] grains, the orientation of a given [beta] grain, deduced by correlating the orientations of the corresponding [alpha] plates measured by E.B.S.P.

  14. Discovering an Accessible Enzyme: Salivary [alpha]-Amylase--"Prima Digestio Fit in Ore"--A Didactic Approach for High School Students

    ERIC Educational Resources Information Center

    Marini, Isabella

    2005-01-01

    Human salivary [alpha]-amylase is used in this experimental approach to introduce biology high school students to the concept of enzyme activity in a dynamic way. Through a series of five easy, rapid, and inexpensive laboratory experiments students learn what the activity of an enzyme consists of: first in a qualitative then in a semi-quantitative…

  15. The dopaminergic stabilizer ASP2314/ACR16 selectively interacts with D2(High) receptors.

    PubMed

    Seeman, Philip; Tokita, Kenichi; Matsumoto, Mitsuyuki; Matsuo, Ayako; Sasamata, Masao; Miyata, Keiji

    2009-10-01

    Dopaminergic stabilizers are recognized as compounds that can either enhance or antagonize dopamine (DA)-dependent behaviors depending on the prevailing dopaminergic tone. The dopaminergic stabilizer ASP2314 is being tested clinically and has been reported to have antipsychotic effects in a clinical trial as an add on medication. To elucidate the mechanisms of action of this dopaminergic stabilizer, its potency on the functional dopamine D2(High) receptors was examined. In competition with D2 receptors selectively labeled by [3H]domperidone, ASP2314 had a dissociation constant, Ki(High), of 1.62 microM for D2(High) in human cloned D2Long receptors and 0.83 muM for rat homogenized striata. Using the D2 agonist ligand [3H](+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol ((+)PHNO), ASP2314 had a high-affinity Ki of 32 nM for D2(High) for rat homogenized striata. ASP2314 stimulated the incorporation of [35S]GTP-gamma-S into rat striata by 50% at 43 nM, and into the cloned D2Long membranes by 50% at 3.2 microM (compared to 100% stimulation by 10 microM dopamine). With similar concentrations of ASP2314 inhibiting the binding of ligands at D2(High) and stimulating [35S]GTP-gamma-S incorporation, the data indicate that the dopaminergic stabilizing action of ASP2314 may be related to the selectivity for the D2(high) state of the D2 receptor.

  16. F-18 high alpha research vehicle surface pressures - Initial in-flight results and correlation with flow visualization and wind-tunnel data

    NASA Technical Reports Server (NTRS)

    Fisher, David F.; Banks, Daniel W.; Richwine, David M.

    1990-01-01

    Flight tests with the NASA F-18 high-alpha research vehicle (HARV) have yielded pressure distributions at angles of attack from 10 to 50 deg, at Mach 0.23 to 0.6, at five fuselage forebody stations and three on the leading-edge extensions (LEXs). Correlations are made between these data and both previously obtained HARV flow visualizations and wind tunnel model test results. The general trend is one in which the forebody's maximum suction pressure peaks increase in magnitude, after their first appearance at alpha of about 19 deg, with increasing alpha. LEX pressure-distribution trends involve the inward progression of the maximum suction peaks, an increase in the magnitude of the maximum pressure peaks up to pressure core breakdown, and the decrease and general flattening of the pressure distribution beyond the LEX primary vortex breakdown.

  17. Mapping of barley alpha-amylases and outer subsite mutants reveals dynamic high-affinity subsites and barriers in the long substrate binding cleft.

    PubMed

    Kandra, Lili; Hachem, Maher Abou; Gyémánt, Gyöngyi; Kramhøft, Birte; Svensson, Birte

    2006-09-18

    Subsite affinity maps of long substrate binding clefts in barley alpha-amylases, obtained using a series of maltooligosaccharides of degree of polymerization of 3-12, revealed unfavorable binding energies at the internal subsites -3 and -5 and at subsites -8 and +3/+4 defining these subsites as binding barriers. Barley alpha-amylase 1 mutants Y105A and T212Y at subsite -6 and +4 resulted in release or anchoring of bound substrate, thus modifying the affinities of other high-affinity subsites (-2 and +2) and barriers. The double mutant Y105A-T212Y displayed a hybrid subsite affinity profile, converting barriers to binding areas. These findings highlight the dynamic binding energy distribution and the versatility of long maltooligosaccharide derivatives in mapping extended binding clefts in alpha-amylases.

  18. Rational design and molecular diversity for the construction of anti-alpha-bungarotoxin antidotes with high affinity and in vivo efficiency.

    PubMed

    Lozzi, Luisa; Lelli, Barbara; Runci, Ylenia; Scali, Silvia; Bernini, Andrea; Falciani, Chiara; Pini, Alessandro; Niccolai, Neri; Neri, Paolo; Bracci, Luisa

    2003-05-01

    The structure of peptide p6.7, a mimotope of the nicotinic receptor ligand site that binds alpha-bungarotoxin and neutralizes its toxicity, was compared to that of the acetylcholine binding protein. The central loop of p6.7, when complexed with alpha-bungarotoxin, fits the structure of the acetylcholine binding protein (AChBP) ligand site, whereas peptide terminal residues seem to be less involved in toxin binding. The minimal binding sequence of p6.7 was confirmed experimentally by synthesis of progressively deleted peptides. Affinity maturation was then achieved by random addition of residues flanking the minimal binding sequence and by selection of new alpha-bungarotoxin binding peptides on the basis of their dissociation kinetic rate. The tetra-branched forms of the resulting high-affinity peptides were effective as antidotes in vivo at a significantly lower dose than the tetra-branched lead peptide.

  19. Alpha fetoprotein

    MedlinePlus

    ... Alpha fetoprotein - series References Cunningham FG, Leveno KJ, Bloom SL, et al. Prenatal diagnosis and fetal therapy. In: Cunningham FG, Leveno KJ, Bloom SL, et al, eds. Williams Obstetrics . 23rd ed. ...

  20. Alpha Thalassemia

    MedlinePlus

    ... an apparently normal individual has a child with hemoglobin H disease or alpha thalassemia minor. It can ... gene on one chromosome 25% 25% 25% 25% hemoglobin H disease there is a 25% chance with ...