Science.gov

Sample records for smectic-c mesophases revealed

  1. Smectic C chevrons in nanocylinders

    SciTech Connect

    Lefort, R. Morineau, D.; Jean, F.; Noirez, L.; Ndao, M.; Cerclier, C. V.

    2014-11-17

    The structure of an achiral smectic-C liquid crystal confined in nanocylinders with a planar surface anchoring is studied by small angle neutron scattering. We observe an invariant alignment of the nematic director with the pore axis, that promotes an original chevron structure with revolution symmetry.

  2. Cholesteric mesophases

    NASA Astrophysics Data System (ADS)

    Sixou, P.; Gilli, J. M.; ten Bosch, A.; Fried, F.; Maïssa, P.; Varichon, L.; Godinho, M. H.

    1991-01-01

    In the past few years, there have been important developments concerning the role and the use of chirality in liquid crystals. An example which is now relatively well known is the chiral smectic C* low molecular weight liquid crystal (LMWLC) which lowers the response time of displays by a factor between one hundred and one thousand [1-3]. In chiral liquid crystal polymers (cholesteric or twisted nematic and smectic C*), it is necessary to understand the relation between the chemical structure and the properties of mesophases in liquid and solid polymer. Furthermore, chirality is also found in abundance in biopolymers and may be important for life processes. Applications in industry (high modulus fibers, sensors, non linear optics...) have already been realised or are being pursued. The aim of this paper is to emphasize the polymer character of these liquid crystals. What is the influence of the molecular weight, the degree of substitution, the viscoelasticity and the existence of a glass transition? How to use the polymer character to obtain new informations on the liquid crystal state or to make new devices? This rapid overview roughly covers the following parts: Formation and general properties of cholesteric mesophases: we give a rapid discussion of thermotropics and lyotropics, of the influence of degree of polymerisation, degree of substitution, concentration, temperature..., on the cholesteric-isotropic transition and on the order observed by textures or as described more quantitatively by the order parameter. Optical properties: we give a brief presentation of a theoretical work concerning the pitch prediction taking into account the asymmetric term in the interaction potential and the comparison with experimental results. Textures and defects which are mainly observed in these mesophases. Flow properties and rheological behaviour which are fundamental for processing. Blue phases near the isotropic-cholesteric transition which are discussed with emphasis on

  3. Smectic-C* alpha-smectic-C* Phase Transition and Critical Point in Binary Mixtures

    SciTech Connect

    Liu,Z.; Wang, S.; McCoy, B.; Cady, A.; Pindak, R.; Caliebe, W.; Takekoshi, K.; Ema, K.; Nguyen, H.; Huang, C.

    2006-01-01

    We have investigated the smectic-C*{sub {alpha}}-smectic-C* (SmC*{sub {alpha}}-SmC*) transition in a series of binary mixtures with resonant x-ray diffraction, differential optical reflectivity, and heat capacity measurements. Results show that the phases are separated by a first-order transition that ends at a critical point. We report the observation of such a critical point. We have proposed the appropriate order parameter and obtained values of two critical exponents associated with this transition. The values of the critical exponents suggest that long-range intersections are present in the SmC*{sub {alpha}}-SmC* critical regions.

  4. What about the Backbone Conformation in Nematic and Smectic C Phases of a ``Side-on'' Fixed LCP? A SANS Study

    NASA Astrophysics Data System (ADS)

    Lecommandoux, S.; Noirez, L.; Achard, M. F.; Hardouin, F.

    1997-10-01

    A polymorphism nematic - smectic C has been revealed for the first time in “side-on” fixed liquid crystalline polymers. By means of neutron investigations, structural and conformational results have been reported in both mesophases. An inversion of the backbone conformation is observed from the nematic phase to the smectic C phase. This new feature is compared to the well known situation of the N SA transition for “side-end” fixed liquid crystal polymers. Un polymorphisme de type nématique - smectique C a été pour la première fois révélé dans les polymères cristaux liquides en “haltère”. Des résultats structuraux et conformationnels obtenus par diffusion cohérente de neutrons sont présentés pour les deux mésophases. Une inversion de la conformation de la chaîne polymère est observée de la phase nématique à la phase smectique C. Ce comportement original est comparé au cas de la transition N SA pour des polymères cristaux liquides en “peigne”.

  5. Unique Pitch Evolution in the Smectic -C-alpha* Phase

    SciTech Connect

    Liu,Z.; McCoy, B.; Wang, S.; Pindak, R.; Caliebe, W.; Barois, P.; Fernandes, P.; Nguyen, H.; Hsu, C.; Wang, .

    2007-01-01

    Employing resonant x-ray diffraction, we observed unique pitch evolutions in the smectic-C{alpha}* phase in mixtures of two antiferroelectric liquid crystals. Our results show that the pitch in this phase continuously evolves across 4 layers, contradicting a theoretical model that predicts that the smectic-C{sub FI2}* phase intervenes in the smectic-C{alpha}* phase. The phase sequences we found can be explained by another model that includes one type of long-range interaction among smectic layers.

  6. Monolayer to interdigitated partial bilayer smectic C transition in thiophene-based spacer mesogens: X-ray diffraction and (13)C nuclear magnetic resonance studies.

    PubMed

    Kesava Reddy, M; Varathan, E; Lobo, Nitin P; Roy, Arun; Narasimhaswamy, T; Ramanathan, K V

    2015-10-06

    Mesophase organization of molecules built with thiophene at the center and linked via flexible spacers to rigid side arm core units and terminal alkoxy chains has been investigated. Thirty homologues realized by varying the span of the spacers as well as the length of the terminal chains have been studied. In addition to the enantiotropic nematic phase observed for all the mesogens, the increase of the spacer as well as the terminal chain lengths resulted in the smectic C phase. The molecular organization in the smectic phase as investigated by temperature dependent X-ray diffraction measurements revealed an interesting behavior that depended on the length of the spacer vis-a-vis the length of the terminal chain. Thus, a tilted interdigitated partial bilayer organization was observed for molecules with a shorter spacer length, while a tilted monolayer arrangement was observed for those with a longer spacer length. High-resolution solid state (13)C NMR studies carried out for representative mesogens indicated a U-shape for all the molecules, indicating that intermolecular interactions and molecular dynamics rather than molecular shape are responsible for the observed behavior. Models for the mesophase organization have been considered and the results understood in terms of segregation of incompatible parts of the mesogens combined with steric frustration leading to the observed lamellar order.

  7. Effects of electrohydrodynamic instability in smectic C liquid crystals

    NASA Astrophysics Data System (ADS)

    Denisova, O. A.; Chuvyrov, A. N.

    2013-03-01

    The effects of electrohydrodynamic instability (EHDI) in smectic C liquid crystals in an electric field are studied. The objects of study are oriented layers of para-hydroxybenzoic acid possessing a smectic phase. The observed effects are divided into three groups according to the character of the motion of molecular centers of mass and the orientation of the director and the smectic C liquid crystal layers. The instabilities of the azimuthal and Kapustin-Williams domains are experimentally found. The experimental cell consists of two glass plates with tin dioxide electrodes separated by Mylar spacers of a specified thickness. Various schemes of domain rotation are considered. The EHDI is found to depend on the layer geometry.

  8. Synthesis, structural and electrochemical characterization of benzimidazole compounds exhibiting a smectic C liquid crystal phase

    NASA Astrophysics Data System (ADS)

    Wei, Bingzhuo; Tan, Shuai; Liang, Ting; Cao, Siyu; Wu, Yong

    2017-04-01

    Mesomorphic benzimidazole compounds were prepared from a biphenyl benzoate based precursor by substitution reaction of alkyl bromide with 2-mercaptobenzimidazole. Molecular structures of the benzimidazole compounds were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy and elemental analysis. Differential scanning calorimetry (DSC) measurements and polarizing optical microscopic (POM) observations revealed that the benzimidazole compounds exhibited a thermotropic smectic C (SC) phase. Temperature dependent X-ray diffraction (XRD) patterns suggested a tilted bilayer smectic structure in which intermolecular hydrogen bonds between benzimidazole moieties formed lamellar arrangement. Electrochemical impedance spectroscopy (EIS) characterization suggested that the SC phase favored anhydrous proton conduction of the benzimidazole compounds and the proton conductivities showed an Arrhenius temperature dependence.

  9. Negative Poisson's ratio and semisoft elasticity of smectic-C liquid-crystal elastomers

    NASA Astrophysics Data System (ADS)

    Brown, A. W.; Adams, J. M.

    2012-01-01

    Models of smectic-C liquid-crystal elastomers predict that they can display soft elasticity, in which the shape of the elastomer changes at no energy cost. The amplitude of the soft mode and the accompanying shears are dependent on the orientation of the layer normal and the director with respect to the stretch axis. We demonstrate that in some geometries the director is forced to rotate perpendicular to the stretch axis, causing lateral expansion of the sample—a negative Poisson's ratio. Current models do not include the effect of imperfections that must be present in the physical sample. We investigate the effect of a simple model of these imperfections on the soft modes in monodomain smectic-C elastomers in a variety of geometries. When stretching parallel to the layer normal (with imposed strain) the elastomer has a negative stiffness once the director starts to rotate. We show that this is a result of the negative Poisson's ratio in this geometry through a simple scalar model.

  10. Dormant mesophase pitch

    SciTech Connect

    Otani, S.

    1984-09-18

    A novel carbonaceous pitch which is optically isotropic in nature and which turns into optically anisotropic when shear forces are applied thereto. The carbonaceous pitch may be obtained by hydrogenating the mesophase of a mesophase pitch to the extent that the mesophase is rendered soluble in quinoline. The carbonaceous pitch is used as a binder and an impregnator and as a precursor material for a highly oriented, high-strength and high-modulus carbon fiber, needle coke or the like carbonaceous materials.

  11. Process for producing mesophase pitch

    SciTech Connect

    Izumi, T.; Igarashi, S.; Naito, T.

    1985-08-06

    A substantially uniform mesophase pitch is prepared by treating a mesophase forming pitch material at elevated temperatures above about 380/sup 0/ C. to produce a mixture of mesophase and non-mesophase pitch containing about 20% to about 80% mesophase. The mixture is then maintained at a temperature below about 400/sup 0/ C. for a time sufficient to allow the mesophase to coalesce and settle as a lower separable layer. A mesophase pitch so produced may contain from 90 to 100% mesophase with a softening point of less than 320/sup 0/ C.

  12. Orientational relaxation in free-standing smectic C film driven by rotating circular frame

    NASA Astrophysics Data System (ADS)

    Zakharov, A. V.; Vakulenko, A. A.

    2015-09-01

    The pecularities in the c ˆ -director reorientation in free-standing smectic C film without of defects and stretched between two circular frames, the rest outer and rotating inner, have been investigated theoretically based on the hydrodynamic theory including the c ˆ -director motion and with accounting for backflow. Since the orientation of the c ˆ -director is fixed at the rims of the smectic film, the shear flow induced by rotating frame winds up of the c ˆ -director field. It is found that the higher shearing flow produces the greater twisting rotation of the c ˆ -director around the normal to the smectic film directed in the opposite sense with respect to the direction of the angular velocity. Calculations also show that the relaxation dynamics of the c ˆ -director field depends crucially on the curvature of the inner rotating frame.

  13. Orientational relaxation in free-standing smectic C film driven by rotating circular frame.

    PubMed

    Zakharov, A V; Vakulenko, A A

    2015-09-14

    The pecularities in the cˆ-director reorientation in free-standing smectic C film without of defects and stretched between two circular frames, the rest outer and rotating inner, have been investigated theoretically based on the hydrodynamic theory including the cˆ-director motion and with accounting for backflow. Since the orientation of the cˆ-director is fixed at the rims of the smectic film, the shear flow induced by rotating frame winds up of the cˆ-director field. It is found that the higher shearing flow produces the greater twisting rotation of the cˆ-director around the normal to the smectic film directed in the opposite sense with respect to the direction of the angular velocity. Calculations also show that the relaxation dynamics of the cˆ-director field depends crucially on the curvature of the inner rotating frame.

  14. Discovery of a Novel Smectic-C Liquid Crystal Phase with Six Layer Periodicity

    SciTech Connect

    Wang, S.; Pindak, R.; Pan, L.D.; Liu, Z.Q; Nguyen, H.T.; Huang, C.C.

    2010-01-13

    We report the discovery of a new smectic-C* liquid-crystal phase with six-layer periodicity by resonant x-ray diffraction. Upon cooling, the new phase appears between the SmC{sub {alpha}}* phase having a helical structure and the SmC{sub d4}* phase with four-layer periodicity. This SmC{sub d6}* phase was identified in two mixtures which have an unusual reversed SmC{sub d4}*-SmC* phase sequence. The SmC{sub d6}* phase shows a distorted clock structure. Three theoretical models have predicted the existence of a six-layer phase. However, our experimental findings are not consistent with the theories.

  15. Pretransitional effects near the smectic-A-smectic-C* phase transition of hydrophilic and hydrophobic aerosil networks dispersed in ferroelectric liquid crystals

    SciTech Connect

    Cordoyiannis, George; Kralj, Samo; Nounesis, George; Kutnjak, Zdravko; Zumer, Slobodan

    2007-02-15

    A detailed x-ray scattering and high-resolution ac calorimetric study has been carried out near the smectic-A to chiral smectic-C phase transition of liquid-crystal compounds 4-(2-methyl butyl) phenyl 4-n-octylbiphenyl-4-carboxylate (CE8) and p-(n-decyloxy) benzylidene-p-amino-(2-methylbutyl) cinnamate (DOBAMBC) confined in hydrophilic and hydrophobic aerosil nanoparticle networks. The character of the transition, which is mean field near a tricritical point in bulk, is changed dramatically with an increase of aerosil-induced disorder. X-ray measurements revealed pretransitional behavior and compression of the smectic layers, phenomena that are strongly pronounced in high aerosil concentrations. A theoretical model that takes into account the interplay of relevant mechanisms is proposed to explain the observed phenomena. The effect of chirality on the interaction of liquid crystals with aerosils is discussed.

  16. Birefringence in the vicinity of the smectic-A to smectic-C phase transition: Crossover from X Y critical to tricritical behavior

    NASA Astrophysics Data System (ADS)

    Das, Malay Kumar; Chakraborty, Susanta; Dabrowski, Roman; Czerwiński, Michał

    2017-01-01

    High-resolution birefringence (Δ n ) measurements are carried out to probe the critical behavior at the smectic-A -smectic-C (Sm-A -Sm-C ) phase transition in a binary system. The critical behavior of this transition is explored with the aid of a differential quotient extracted from the Δ n values. The results obtained reveal that the Sm-A -Sm-C and nematic-smectic-A (N -Sm-A ) transitions exhibit nonuniversal behaviors with effective exponents lying between the tricritical and three-dimensional X Y values and follow two distinctly different curves with decreasing width of the Sm-A and N phases, respectively. The origin of such critical behavior is a unique feature for the respective phase transitions.

  17. 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.

  18. Pressure settling of mesophase

    SciTech Connect

    Romine, H.E.

    1989-05-23

    This patent describes a process for producing mesophase pitch wherein a heavy aromatic hydrocarbon feedstock is heat soaked at a first pressure until a substantial portion of the feedstock has been converted to optically anisotropic material, and in which mesophase pitch is recovered from the heat soaked material by gravity settling, the improvement comprises: subjecting and maintaining for a time of up to about 15 minutes the heat soaked material, prior to recovery of mesophase pitch therefrom, to a second pressure which is at least 30 kPa higher than the first pressure for a time of up to about 15 minutes, whereby boiling of the heat soaked material is reduced and settling of mesophase pitch is enhanced.

  19. Polarity sensitive electric responses in a twisted smectic-C liquid crystal

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, K. S.

    2013-12-01

    The observation of two polarity-sensitive electrical responses found in the low-frequency (<1 Hz) regime of a square wave field is reported for an achiral rodlike smectic-C liquid crystal with negative dielectric and conductivity anisotropies and in the 90°-twisted configuration. The first involves a transient director modulation appearing at each polarity reversal and vanishing under steady field conditions. The instability is polarity sensitive, with the maximum distortion localized near the negative electrode instead of the sample midplane. This is inferred from the wave-vector orientation alternating in the two halves of the driving cycle between the alignment directions at the two substrates. Various electro-optic characteristics of this temporal phenomenon are also described. Following a similar observation in nematic liquid crystals, we associate the transient periodic order with the Carr-Helfrich mechanism assisted by quadrupolar flexoelectric polarization obtaining under electric field gradients. The second polarity-sensitive effect manifests in the relative shift of the periodic Fréedericksz pattern upon field reversal. The shift, which is linear in field for low fields, tends to saturate for large fields. It is interpreted as due to flexoelectric polarization associated primarily with the c director twist about the layer normal. A model involving a periodic wedgelike band, which has the twist localized within it and is flanked by two uniformly and transversely aligned regions, accounts for the flexoelectric shift of the optical pattern.

  20. Process for producing mesophase pitch

    SciTech Connect

    Isumi, T.; Naito, T.; Igarashi, S.

    1988-11-29

    This patient describes process for producing a mesophase pitch having a mesophase content of above 90% and a softening point of below 320/sup 0/ C. comprising the steps of: heat-treating a pitch forming material at elevated temperatures above about 380/sup 0/C for a time sufficient to provide a mixture of mesophase and non-mesophase pitch containing about 20% to about 80% (by weight) of mesophase and a softening point of no greater than 250/sup 0/C; aging and settling the mesophase portion of the mixture of mesophase and non-mesophase pitch obtained in step by maintaining the mixture in a substantially quiescent condition and at a temperature below the temperature in the heat-treating step, at which temperature the mixture is sufficiently liquid so that the separation of the mesophase and non-mesophase portions of the mixture can be substantially accomplished, (and above about 350/sup 0/C) for a time sufficient for the mesophase portion of the mixture to coalesce and accumulate into a substantially lower homogeneous mesophase pitch layer containing at least 90% mesophase and an upper layer comprising the non-mesophase portion of the mixture; and separating the lower mesophase layer from the upper non-mesophase layer whereby a mesophase pitch which has a mesopphase content of above 90% and a softening point below 320/sup 0/C is obtained. heat-treated at a temperature in the range of about 380/sup 0/C to about 460/sup 0/C whereby thermal cracking and polycondensation reaction occur.

  1. Method for producing mesophase continuously

    SciTech Connect

    Watanabe, M.

    1985-04-23

    A method for producing continuously 100% mesophase composed only of Q.I. component and Q.S. component in which a raw material of petroleum origin pitch is subjected continuously to a heat-treatment step in an amount necessary to produce a 100% mesophase taken out from a mesophase-growing and coalescing step, transferring the heat-formed pitch formed in the heat treatment step to a mesophase growing and coalescing step, taking out a definite amount of a non-mesophase pitch from the mesophase growing and coalescing step after stirring and heating treatment to return it to the heat-treatment step to repeat the stirring and heating treatment, and at the same time to take out 100% mesophase having constant properties from the mesophase growing and coalescing step.

  2. Process for producing mesophase pitch

    SciTech Connect

    Shibatani, H.; Kameda, T.; Takahashi, K.

    1985-07-09

    Mesophase pitch containing quinoline soluble mesophase is produced from a pitch having a specific aromatic hydrogen content with a short heat treatment time without conducting any special treatment such as extraction.

  3. Process for isolating mesophase pitch

    SciTech Connect

    Romine, H.E.; McConaghy, J.R. Jr.

    1991-07-16

    This patent describes a process for the preparation of mesophase pitch. It comprises combining an isotropic pitch containing mesogens with a solvent, effecting phase separation of the mesogens from the isotropic pitch under solvent supercritical conditions of temperature and pressure, wherein the mesogens associate together under solvent supercritical conditions of temperature and pressure to form mesophase pitch; and recovering mesophase pitch.

  4. Low melting mesophase pitches

    SciTech Connect

    Diefendorf, R.J.; Chen, S.H.

    1984-04-17

    A low melting point, low molecular weight, heptane insoluble, 1,2,4-trichlorobenzene soluble mesophase pitch useful in carbon fiber spinning as such or as a plasticizer in a carbon fiber spinning composition is obtained by heating chrysene, triphenylene or paraterphenyl as well as mixtures thereof and hydrocarbon fractions containing the same, dissolving the resulting heat treated material with 1,2,4-trichlorobenzene, and separating the insolubles, and then contacting the 1,2,4-trichlorobenzene soluble fraction with a sufficient amount of heptane to precipitate the low melting point, low molecular weight mesophase pitch.

  5. Method for producing mesophase pitch

    SciTech Connect

    Watarabe, M.

    1985-07-16

    A method for producing a 100% mesophase pitch composed only of Q.I. and Q.S. components is provided. This method comprises subjecting petroleum-origin pitch to heat treatment with stirring under a stream of a hydrocarbon gas of small carbon atom numbers at atmospheric or superatmospheric pressure, holding said heat-treated pitch in quiescent state to melt and coalesce only the mesophase therein and dividing and separating non-mesophase and mesophase layers. Resulting 100% mesophase enables us to produce high strength, high modulus carbon fibers.

  6. Method for producing mesophase pitch

    SciTech Connect

    Watanale, M.

    1985-07-16

    A method for producing a 100% mesophase composed only of Q.I. component and Q.S. component is provived. This method comprises forming mesophase by the heat treatment of petroleum-origin pitch, subjecting the heat-formed pitch to a condition of heating under quiescent state to cause only the mesophase in the heat-formed pitch to grow and coalesce, separating only the non-mesophase of the upper layer and repeating the operation of the heat treatment and maintenance of heating under a quiescent state by the separated non-mesophase, as a raw material.

  7. 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.

  8. Mesophase Behavior in Carbon Fiber Bundles.

    DTIC Science & Technology

    1982-06-01

    Mesophase Coal-tar pitch Mesophase bloating Composite fabrication Mesophase wetting Ccmposite micrography Petroleum pitch 20. Atl RACT (Continue on reve...fiber in petroleum pitch were pyrolyzed under three conditions of constraint. The results confirm a recent report that the mesophase transformation...proceeds differently within a fiber bundle than in bulk pitch . In the early stages of transformation, both pitch and mesophase wet the fiber, and the

  9. Mesophase from anthracene oil-based pitches

    SciTech Connect

    P. Alvarez; J. Sutil; R. Santamaria; C. Blanco; R. Menendez; M. Granda

    2008-11-15

    This work deals with the preparation of the mesophase from two pitch-like materials obtained from anthracene oil by oxidative thermal condensation (AOP-1) and the subsequent thermal treatment and distillation of AOP-1 (AOP-2). The mesophase was obtained by the controlled pyrolysis (440-470{degree}C and different periods of residence times) and subsequent sedimentation of the samples. In the case of the pitch prepared by oxidative thermal condensation, a dynamic pressure of 5 bar was applied during the pyrolysis. The pressure was a critical parameter, and its influence was also investigated. The results show that AOP-1 requires higher temperatures and/or residence times to develop mesophase than AOP-2. After sedimentation, a sample consisting of mainly mesophase was produced in all of the cases. The characterization of the mesophases by means of techniques, such as elemental and thermogravimetric analysis and optical microscopy, showed that anthracene oil-based derivatives are appropriate precursors for producing QI-free mesophase with suitable properties for the fabrication of a wide range of carbon materials. 26 refs., 5 figs., 3 tabs.

  10. Crystallizing Membrane Proteins Using Lipidic Mesophases

    PubMed Central

    Caffrey, Martin; Cherezov, Vadim

    2009-01-01

    A detailed protocol for crystallizing membrane proteins that makes use of lipidic mesophases is described. This has variously been referred to as the lipid cubic phase or in meso method. The method has been shown to be quite general in that it has been used to solve X-ray crystallographic structures of prokaryotic and eukaryotic proteins, proteins that are monomeric, homo- and hetero-multimeric, chromophore-containing and chromophore-free, and α-helical and β-barrel proteins. Its most recent successes are the human engineered β2-adrenergic and adenosine A2A G protein-coupled receptors. Protocols are provided for preparing and characterizing the lipidic mesophase, for reconstituting the protein into the monoolein-based mesophase, for functional assay of the protein in the mesophase, and for setting up crystallizations in manual mode. Methods for harvesting micro-crystals are also described. The time required to prepare the protein-loaded mesophase and to set up a crystallization plate manually is about one hour. PMID:19390528

  11. The steady and transient rheological behavior or mesophase pitches

    SciTech Connect

    Fleurot, O.; Edie, D.D.

    1996-12-31

    Carbonaceous mesophase, a discotic, nematic liquid crystal, is a common precursor for the production of high performance (high thermal conductivity) carbon fibers. During melt spinning of mesophase pitches into fiber form, the poly-domain structure is stretched and oriented. A highly-oriented as-spun structure can be readily graphitized, giving the final heat-treated fiber superior thermal properties. Obviously, understanding, predicting, and ultimately controlling the development of structure is critical, if the final properties of mesophase pitch carbon fibers are to be optimized. While the development of structure in mesophase has been qualitatively described, quantitative information is needed. Complicating factors are: (i) the physical properties of mesophase pitches depend on the nature of the precursor material used to produce the liquid crystalline fluid, (ii) the rheological properties of mesophase are highly temperature-dependent, and (iii) mesophase pitch is optically opaque. In this work, the development of structure during steady and transient flow was investigated for different mesophase pitches.

  12. Double epitaxy as a paradigm for templated growth of highly ordered three-dimensional mesophase crystals

    SciTech Connect

    Shin, Yongsoon; Tao, Jinhui; Arey, Bruce W.; Wang, Chongmin; Exarhos, Gregory J.; De Yoreo, James J.; Sushko, Maria L.; Liu, Jun

    2016-08-30

    Molecular templating and self-assembly are fundamental mechanisms for controlling the morphology of biominerals, while in synthetic two-dimensional layered materials similar levels of control over materials structure can be achieved through the epitaxial relationship with the substrate. In this study these two concepts are combined to provide an approach for the nucleation and growth of three-dimensional ordered mesophases on solid surfaces. A combined experimental and theoretical study revealed how atomic ordering of the substrate controls the structure of surfactant template and the orientation and morphology of the epitaxially grown inorganic material. Such dual epitaxial relationship between the substrate, surfactant template and inorganic mesophase gives rise to a highly ordered porous mesophase with a well-defined cubic lattice of pores. The level of control over material’s three-dimensional architecture achieved in this one-step synthesis is reminiscent to that in biomineralization.

  13. Formation and behavior of carbonaceous mesophase in petroleum pitch

    SciTech Connect

    Stevens, W.C.

    1985-01-01

    The phase behavior of conventional liquid crystals with nonmesomorphs was studied and compared to mixtures of mesophase pitches with aromatic molecules. Experimental phase diagrams of p-polyphenyls, p-azoxyanisol and various aromatic molecules were used to estimate the virtual mesophase-isotropic transition temperatures of the latter. The mesophase-isotropic transition in mesophase pitch, hidden by reactions, decreases the solubility of nonmesomorphs as would be predicted by the phase behavior of conventional liquid crystals. From vapor osmometry, gel permeation chromatography and elemental analysis, models of Ashland 240 and a solvent extracted Ashland 240 mesophase pitch were developed. The 3 to 5-ringed aromatic species contained within Ashland 240 are the polymerized subunits forming the branched molecules of the solvent extracted mesophase pitch. The effects of air blowing, sparging and heat soaking on the nature and constitution of mesophase formed from Ashland 240 pitch also were examined and compared to the solvent extracted pitch. The nature and consequently the behavior of the mesophase formed was found to be process dependent. The utility of mesophase pitches is derived largely from the local molecular orientation. Experimentally observed changes in local order as a function of temperature and time at temperature were attributed to the hidden mesophase-isotropic transition temperature and the reactions which mask this transition. The orientation, relaxation, and stabilization of locally ordered subunits into an overall preferred orientation was examined by melt spinning mesophase pitches into fibers.

  14. Molecular Dynamics in a Liquid Crystal with Reentrant Mesophases

    NASA Astrophysics Data System (ADS)

    Sebastião, P. J.; Ribeiro, A. C.; Nguyen, H. T.; Noack, F.

    1995-11-01

    It is well known that liquid crystalline compounds with a cyano terminal group can present peculiar polymorphisms in particular different types of smectic A mesophases and a reentrant behaviour for both nematic and smectic A mesophases. In this work we study by proton NMR relaxation the influence of these features on the molecular dynamics of the compound 4-cyanobenzoate-4'-octylbenzoyloxyphenyl (DB8CN Sym) in its nematic (N), partial bilayer smectic A (SAd), reentrant nematic (Nre) and reentrant smectic A (SA1) mesophases. Standard and fast field-cycling techniques were used for our spin-lattice relaxation's study over a broad frequency range of 6 decades (200 Hz up to 300 MHz). It was found that the molecular dynamics in the nematic mesophases is rather different from the molecular dynamics in the smectic A mesophases. However, the reentrant aspect present in both nematic and smectic A states is not associated to a major difference on the molecular dynamics of the nematic and reentrant nematic or smectic and reentrant smectic A mesophases. Order director fluctuations and rotations/reorientations are the most important relaxation mechanisms in the nematic mesophases in the lower and higher frequency limits, respectively, while self-diffusion has a very small contribution to the overall relaxation. As for the smectic A mesophases, self-diffusion and rotations/reorientations are the predominant relaxation mechanisms for frequencies above 20 kHz. The collective motions, which for these mesophases have to be associated with layer undulations with the frequency law T_1sim ν, are only important to the spin-lattice relaxation on the low part of the frequency spectrum (ν<10 kHz). The inclusion in the relaxation study of a contribution from the cross-relaxation between protons and nitrogen nuclei improves the quality of the 1/T_1 data fits in both kinds of mesophases. The combined study of the molecular dynamics in the N, SAd, Nre and SA1 mesophases of DB8CN Sym reveals

  15. Penetratin-induced transdermal delivery from H(II) mesophases of sodium diclofenac.

    PubMed

    Cohen-Avrahami, Marganit; Libster, Dima; Aserin, Abraham; Garti, Nissim

    2012-05-10

    Penetratin, a cell penetrating peptide is embedded within a reversed hexagonal (H(II)) mesophase for improved transdermal delivery of sodium diclofenac (Na-DFC). The H(II) mesophase serves as the solubilization reservoir and gel matrix whereas penetratin is the transdermal penetration enhancer for the drug. The systems were characterized and the interactions between the components were determined by SAXS, ATR-FTIR and SD-NMR. High affinity of Na-DFC to glycerol monooleate (GMO) was revealed, associated with increasing the order within the water channels. This affinity is enhanced upon heating and seems to be associated with GMO dehydration. Penetratin (PEN) is entrapped at the hydrophilic region of the H(II) mesophase, between the GMO headgroups, reducing the order of the system and decreasing the size of the hexagonal domains. The transdermal delivery rate of Na-DFC through porcine skin, from the H(II) mesophases, was enhanced by PEN and so also the cumulative transport crossing the skin. PEN induced accelerated drug diffusion through the stratum corneum, towards the different skin layers. The transdermal delivery enhancement is explained from the results of the ATR-FTIR analysis. It seems that PEN accelerates the structural transition of skin lipids from hexagonal to liquid. The disordering results in enhanced diffusion of Na-DFC through the stratum corneum, followed by enhanced overall penetration of the drug.

  16. Process for the preparation of mesophase pitches

    SciTech Connect

    Tsuchitani, M.; Naito, S.; Nakajima, R.

    1989-05-11

    A process is described for preparing a mesophase pitch with a Mettler method softening point of lower than 320/sup 0/C, a mesophase content of higher than 90% when examined on a polarized microscope, a quinoline insoluble content of lower than 20% and a xylene soluble content of lower than 20% for manufacturing high performance carbon fibers comprising: (a) subjecting a heavy oil of petroleum or coal origin, or a heavy component obtainable from the heavy oil, the oil or component having substantially no xylene insoluble component, to a heat treatment in a tubular heater at a temperature of 400/sup 0/ to 600/sup 0/C under a pressure of 1 to 100 Kg/cm/sup 2/.G measured at the outlet of the tubular heater for 1 to 2000 sec so as to obtain a heat-treated material having 3 to 30 wt% of xylene insoluble component; (b) adding to the thus heat-treated material a monocyclic aromatic hydrocarbon solvent in an amount of 1 to 5 times on the heat-treated material, and recovering the newly formed insoluble component as an essentially isotropic high molecular weight bituminous material; (c) subjecting the high molecular weight bituminous material to a hydrogenation treatment at a temperature of 400/sup 0/ to 460/sup 0/C and a pressure of 20 to 200 Kg/cm/sup 2/.G with the addition of 1 to 5 times amount of a hydrogen-donating solvent based on the high molecular weight bituminous material thereby obtaining an essentially isotropic hydrogenated pitch; and (d) heat treating the hydrogenated pitch at 350/sup 0/ to 500/sup 0/C under a pressure up to atmospheric pressure to convert the hydrogenated pitch into the mesophase pitch.

  17. Boronated mesophase pitch coke for lithium insertion

    NASA Astrophysics Data System (ADS)

    Frackowiak, E.; Machnikowski, J.; Kaczmarska, H.; Béguin, F.

    Boronated carbons from mesophase pitch have been used as materials for lithium storage in Li/carbon cells. Doping by boron has been realized by co-pyrolysis of coal tar pitch with the pyridine-borane complex. Amount of boron in mesocarbon microbeads (MCMB) varied from 1.4 to 1.8 wt.% affecting the texture of carbon. Optical microscopy and X-ray diffractograms have shown tendency to more disordered structure for boron-doped carbon. The values of specific reversible capacity ( x) varied from 0.7 to 1.1 depending significantly on the final temperature of pyrolysis (700-1150°C). The optimal charge/discharge performance was observed for boronated carbon heated at 1000°C.

  18. Stabilization and carbonization of mesophase pitch nanofiber

    NASA Astrophysics Data System (ADS)

    Fong, Hao; Reneker, Darrell H.

    2000-03-01

    Mesophase pitch nanofibers were made with diameters of several hundred nanometers to a few microns. Thermogravimetric analysis showed the stabilization reaction in air began at a temperature below 200^oC, and produced a 6% weight gain. Changes intensity of aliphatic C-H (2850-3000 and 1400-1450 cm-1) and carbonyl -CO- (1690-1750 cm-1) peaks in Fourier transform infrared spectra were observed as a result of stabilization. The intensities of aryl alkyl ether peaks at 1200-1275 cm-1 increased with stabilization in air. Solid state NMR results confirmed these changes. Carbonization in inert gas began when the temperature reached 300^oC. There was a 25% weight loss during the carbonization. Element analysis showed that the only carbon remained. The structures of pitch nanofibers, stabilized nanofibers and the resulting carbon nanofibers were investigated with scanning electron microscopy, transmission electron microscopy and X-ray diffraction.

  19. Tailoring the properties of polymers via formation of a mesophase

    SciTech Connect

    Di Girolamo, Rocco Auriemma, Finizia; De Rosa, Claudio; Malafronte, Anna

    2015-12-17

    The combination of the control of the concentration of stereodefects in isotactic polypropylene using metallocene catalysts and the crystallization via the mesophase is a strategy to tailor the mechanical properties. Stiff materials, flexible materials, and thermoplastic elastomers can be produced depending only on the concentration of rr stereodefects. We show that in the case of isotactic polypropylene (iPP) the material properties can be finely tuned at molecular level via formation of a solid mesophase, characterized by an intermediate degree of order between amorphous and crystalline state. The effect of different degree of stereoregularity on the mesophase formation, thermal stability, morphology, is analyzed at different length scales, using different technique including wide angle X-ray scattering, atomic and optical microscopy. Different morphologies are observed depending on the stereoregularity and conditions of crystallization. In contrast to the lamellar morphology of crystals normally obtained from the melt, the solid mesophase show a nodular morphology.

  20. Chemical activation of carbon mesophase pitches.

    PubMed

    Mora, E; Blanco, C; Pajares, J A; Santamaría, R; Menéndez, R

    2006-06-01

    This paper studies the chemical activation of mesophase pitches of different origins in order to obtain activated carbons suitable for use as electrodes in supercapacitors. The effect that the activating agent (NaOH, LiOH, and KOH), the alkaline hydroxide/pitch ratio, and the activation temperature had on the characteristics of the resultant activated carbons was studied. LiOH was found to be a noneffective activating agent, while activation with NaOH and KOH yielded activated carbons with high apparent surface areas and pore volumes. The increase of the KOH/pitch ratio caused an increase of the chemical attack on the carbon, producing higher burnoffs and development of porosity. Extremely high apparent surface areas were obtained when the petroleum pitch was activated with 5:1 KOH/carbon ratio. The increase of the activation temperature caused an increase of the burnoff, although the differences were not as significant as those derived from the use of different proportions of activating agent.

  1. Solubilization of vitamin E into H(II) LLC mesophase in the presence and in the absence of vitamin C.

    PubMed

    Bitan-Cherbakovsky, Liron; Yuli-Amar, Idit; Aserin, Abraham; Garti, Nissim

    2010-03-02

    The synergistic solubilization of two major hydrophilic (vitamin C, ascorbic acid, AA) and lipophilic (vitamin E, D-alpha-tocopherol, VE) antioxidants within reverse hexagonal (H(II)) mesophases is reported. The H(II) mesophases are composed of monoolein (GMO)/VE/AA/water. A wide range of VE concentration was examined (on the expense of GMO concentrations) while the AA and water concentrations remained constant (4 and 12.5 wt %, respectively) in order to expand the H(II) mesophase. SAXS and DSC combined with ATR-FTIR techniques were utilized to study the interactions between each solubilizate and the H(II) component that enabled the synergistic accommodation of the hydrophilic and hydrophobic molecules. It was revealed that up to 27 wt % VE solubilized within the H(II) mesophase. This hydrophobic additive localized at the lipophilic GMO tail region solvating the surfactant tails, thereby enabling the formation of the H(II) structure. As a result, the lattice parameter and the melting point of the hydrophobic tails decreased. Above 27 wt % VE (up to 33 wt %), once the GMO lipophilic region was homogenously solvated, additional VE molecules located closer to the interface. At this range of concentrations, new hydrogen bonds between O-H groups of VE and O-H groups of GMO were formed. Once 35 wt % VE was introduced, the H(II) structure transformed to face-centered reverse micellar cubic phase (Fd3m, Q(227)).

  2. Food volatile compounds facilitating HII mesophase formation: solubilization and stability.

    PubMed

    Amar-Zrihen, Natali; Aserin, Abraham; Garti, Nissim

    2011-05-25

    Four lipophilic food volatile molecules of different chemical characteristics, phenylacetaldehyde, 2,6-dimethyl-5-heptenal, linalool, and trans-4-decenal, were solubilized into binary mixtures of monoolein/water, facilitating the formation of reverse hexagonal (H(II)) mesophases at room temperature without the need of solvents or triglycerides. Some of the flavor compounds are important building blocks of the hexagonal mesostructure, preventing phase transition with aging. The solubilization loads were relatively high: 12.6, 10.0, 12.6, and 10.0 wt % for phenylacetaldehyde, 2,6-dimethyl-5-heptenal, linalool, and trans-4-decenal, respectively. Phenylacetaldehyde formed mixtures of lamellar and cubic phases. Linalool, 2,6-dimethyl-5-heptenal, and trans-4-decenal induced structural shift from lamellar directly to H(II) mesophase, remaining stable at room temperature. Lattice parameters were found to increase with water content and to decrease with temperature and/or food volatile content. trans-4-Decenal produces more stable H(II) mesophase compared to linalool-loaded mesophase. At 40-60 °C, depending on the chemical structure and on the solubilization location of the food volatile compounds, the H(II) mesophase transforms to isotropic micellar phase, facilitating the release of the food volatile compounds. Molecular interactions suggest the existence of two consecutive stages in the solubilization process.

  3. Mesophase pitches, carbon fiber precursors, and carbonized fibers

    SciTech Connect

    Sumner, M.B.; Hettinger, M.P.

    1993-08-24

    A process is described for the production of a stabilized carbon fiber which process comprises: forming a film having a thickness in the range of about 0.025 mm (0.001 in) to about 2.5 mm (0.1 in), of a catalytic pitch; maintaining said film at a temperature in the range of about 327 C to about 427 C and a pressure in the range of about 20 microns of mercury to about 1 atm for a time that is sufficient to produce a heavy isotropic pitch having a softening point in the range of about 127 C to about 288 C, a coking value in the range of about 55 wt % to about 95 wt %, and a maximum mesophase content of 5 vol %; agitating said heavy isotropic pitch while passing an inert gas through said heavy isotropic pitch at a rate of up to about 30 SCFH/1b at a temperature in the range of about 327 C to about 454 C for a time that is sufficient to provide a mesophase pitch having a vol. % of mesophase of at least 60; converting said mesophase pitch into green fibers; and stabilizing for a minimum time ranging from about 14 to about 288 minutes said green fibers with an oxidizing agent while heating said green fibers to a starting temperature of about 41 C to 221 C that is below the glass transition temperature of the mesophase pitch, and thereafter increasing the temperature of said green fiber at a rate of between about 1 C/min and 6 C/min to a final temperature in the range of about 282 C to 343 C to provide a stabilized carbon fiber.

  4. Optical patterning of photosensitive thin film silica mesophases

    SciTech Connect

    DOSHI,DHAVAL A.; HUESING,NICOLA K.; LU,MENGCHENG; FAN,HONGYOU; HURD,ALAN J.; BRINKER,C. JEFFREY

    2000-02-09

    Photosensitive films incorporating molecular photoacid generators compartmentalized within a silica-surfactant mesophase were prepared by an evaporation-induced self-assembly process. UV-exposure promoted localized acid-catalyzed siloxane condensation, enabling selective etching of unexposed regions, thereby serving as a resistless technique to prepare patterned mesoporous silica. The authors also demonstrated an optically-defined mesophase transformation (hexagonal {r_arrow} tetragonal) and patterning of refractive index and wetting behavior. Spatial control of structure and function on the macro- and mesoscales is of interest for sensor arrays, nano-reactors, photonic and fluidic devices, and low dielectric constant films. More importantly, it extends the capabilities of conventional lithography from spatially defining the presence or absence of film to spatial control of film structure and function.

  5. Columnar mesophases of hexabenzocoronene derivatives. II. Charge carrier mobility

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, James; Marcon, Valentina; Kremer, Kurt; Nelson, Jenny; Andrienko, Denis

    2008-09-01

    Combining atomistic molecular dynamic simulations, Marcus-Hush theory description of charge transport rates, and master equation description of charge dynamics, we correlate the temperature-driven change of the mesophase structure with the change of charge carrier mobilities in columnar phases of hexabenzocoronene derivatives. The time dependence of fluctuations in transfer integrals shows that static disorder is predominant in determining charge transport characteristics. Both site energies and transfer integrals are distributed because of disorder in the molecular arrangement. It is shown that the contributions to the site energies from polarization and electrostatic effects are of opposite sign for positive charges. We look at three mesophases of hexabenzocoronene: herringbone, discotic, and columnar disordered. All results are compared to time resolved microwave conductivity data and show excellent agreement with no fitting parameters.

  6. Frank elastic constants in LC mesophases of polymeric semiconductors

    NASA Astrophysics Data System (ADS)

    Gemuenden, Patrick; Kremer, Kurt; Daoulas, Kostas Ch.

    2014-03-01

    Liquid crystalline (LC) mesophases of polymeric semiconductors, e.g. poly(alkylthiophenes), can facilitate processing to obtain morphologies with improved properties. We develop a particle-based modeling approach to study nematic mesophases of such systems. The method uses soft, directional interactions and is inspired by field theoretical approaches to LCs. It enables us to generate large morphologies and calculate Frank elastic constants (FC). Besides interesting theoretical questions related to the behavior of FCs in polymer nematics, they are important when linking particle-based with continuum media descriptions of LCs. We calculate FC related to bend, splay and twist deformations from the fluctuation spectra of the local nematic director. The magnitudes of FC measured in the simulations agree with those reported in experiments on polymer nematics. We discuss their dependence on system parameters, e.g. chain length, and we compare with predictions by analytical field theory. This work was partially supported by BMBF grant MORPHEUS (FKZ 13N11704).

  7. Unusual structural evolution of poly(lactic acid) upon annealing in the presence of an initially oriented mesophase.

    PubMed

    Wang, Yaming; Li, Ming; Wang, Kaojin; Shao, Chunguang; Li, Qian; Shen, Changyu

    2014-03-14

    Uniaxial deformations of amorphous poly(lactic acid) (PLA) films were performed at two different temperatures, 70 and 80 °C, at various draw strains. The samples deformed at 70 °C showed a strain-induced mesophase, and the structural ordering and thermal stability increased as the draw strain increased. Further annealing was performed in situ at constant length at the drawing temperature of 70 °C for the films drawn to strains of 100% and 230%. Unusually, we found that after annealing, the crystal structure of the film at lower strain was more ordered than the one at higher strain. Further investigations revealed that upon annealing the structural evolution followed a distinct molecular mechanism for the samples stretched to the two draw strains. For the sample drawn to 100%, the mesophase melted very quickly upon annealing, resulting in chain randomization and the release of the constraints on the thermodynamic relaxation of the oriented amorphous chains. The chain relaxation motions had a beneficial effect on the occurrence of the conformational rearrangements that are necessary for crystalline ordering. By contrast, for the 230% sample, the melting of the mesophase was slow and most of the chain orientations were preserved upon annealing. As a result, a less ordered crystal structure was formed since the local relaxation motions that are necessary for promoting crystalline order via conformational rearrangements were hindered.

  8. Crystallizing Membrane Proteins in Lipidic Mesophases. A Host Lipid Screen

    SciTech Connect

    Li, Dianfan; Lee, Jean; Caffrey, Martin

    2011-11-30

    The default lipid for the bulk of the crystallogenesis studies performed to date using the cubic mesophase method is monoolein. There is no good reason, however, why this 18-carbon, cis-monounsaturated monoacylglycerol should be the preferred lipid for all target membrane proteins. The latter come from an array of biomembrane types with varying properties that include hydrophobic thickness, intrinsic curvature, lateral pressure profile, lipid and protein makeup, and compositional asymmetry. Thus, it seems reasonable that screening for crystallizability based on the identity of the lipid creating the hosting mesophase would be worthwhile. For this, monoacylglycerols with differing acyl chain characteristics, such as length and olefinic bond position, must be available. A lipid synthesis and purification program is in place in the author's laboratory to serve this need. In the current study with the outer membrane sugar transporter, OprB, we demonstrate the utility of host lipid screening as a means for generating diffraction-quality crystals. Host lipid screening is likely to prove a generally useful strategy for mesophase-based crystallization of membrane proteins.

  9. Degree of disorder in cubic mesophases in thermotropics: thermodynamic study of a liquid crystal showing two cubic mesophases.

    PubMed

    Saito, Kazuya; Shinhara, Takashi; Nakamoto, Tadahiro; Kutsumizu, Shoichi; Yano, S; Sorai, Michio

    2002-03-01

    Heat capacity of a thermotropic mesogen ANBC(22) (4(')-alkoxy-3(')-nitrobiphenyl-4-carboxylic acid with 22 carbon atoms in alkyl chain) showing two cubic mesophases was measured by adiabatic calorimetry between 13 and 480 K. Excess enthalpies and entropies due to phase transitions were determined. A small thermal anomaly due to the cubic Im3m-->cubic Ia3d phase transition was successfully detected. Through an analysis of chain-length dependence of the entropy of transition, the sequence of two cubic mesophases (with space groups Ia3d and Im3m) is deduced for thermotropic mesogens ANBC(n). It is shown that the disorder of the core arrangement decreases in the order of Sm-C-->cubic (Im3m)-->cubic (Ia3d) while that of the chain in the reverse order cubic (Ia3d)-->cubic (Im3m)-->Sm C.

  10. A study on the effect of heat treatment temperature on mesophase development in coal tar pitch

    NASA Astrophysics Data System (ADS)

    Soni, Neha; Shah, Raviraj K.; Shrivastava, Rakesh; Datar, Manoj

    2013-06-01

    In the present study, a zero quinoline insoluble (QI) isotropic coal tar pitch was taken for the preparation of mesophase pitch. The pitch was heated in inert atmosphere at different heat treatment temperatures keeping same heating rate and soaking time to study the formation, growth and coalescence of mesophase spheres in the pitch. Such pitches were characterized for insoluble content (QI & TI), mesophase content, sulphur content, weight loss in inert atmosphere, softening point, coking value (CVC), C/H ratio etc. Results show that the insoluble content (QI & TI) and mesophase content of pitch increase with increase of heat treatment temperature.

  11. Identification of a potential conformationally disordered mesophase in a small molecule: experimental and computational approaches.

    PubMed

    Chakravarty, Paroma; Bates, Simon; Thomas, Leonard

    2013-08-05

    GNE068, a small organic molecule, was obtained as an amorphous form (GNE068-A) after isolation from ethanol and as a partially disordered form (GNE068-PC) from ethyl acetate. On subsequent characterization, GNE068-PC exhibited a number of properties that were anomalous for a two phase crystalline-amorphous system but consistent with the presence of a solid state phase having intermediate order (mesomorphous). Modulated DSC measurements of GNE068-PC revealed an overlapping endotherm and glass transition in the 135-145 °C range. ΔH of the endotherm showed strong heating rate dependence. Variable temperature XRPD (25-160 °C) revealed structure loss in GNE068-PC, suggesting the endotherm to be an "apparent melt". In addition, gentle grinding of GNE068-PC in a mortar led to a marked decrease in XRPD peak intensities, indicating a "soft" crystalline lattice. Computational analysis of XRPD data revealed the presence of two noncrystalline contributions, one of which was associated with GNE068-A. The second was a variable component that could be modeled as diffuse scattering from local disorder within the associated crystal structure, suggesting a mesomorphous system. Owing to the dominance of the noncrystalline diffuse scattering in GNE068-PC and the observed lattice deformation, the mesomorphous phase exhibited properties consistent with a conformationally disordered mesophase. Because of the intimate association of the residual solvent (ethyl acetate) with the lattice long-range order, loss of solvent on heating through the glass transition temperature of the local disorder caused irrecoverable loss of the long-range order. This precluded the observation of characteristic thermodynamic mesophase behavior above the glass transition temperature.

  12. Crowded Star Mesogens: Guest-Controlled Stability of Mesophases from Unconventional Liquid-Crystal Molecules.

    PubMed

    Lehmann, Matthias; Maier, Philipp; Grüne, Matthias; Hügel, Markus

    2017-01-23

    The molecular design of crowded hexasubstituted star mesogens based on a benzene core and alternating substitution with oligo(phenylenevinylene) arms and aryl units generates free space between the conjugated arm scaffolds. Various arylcarboxy building blocks, decorated with alkoxy chains, have been incorporated in the void by mixing, hydrogen bonding or covalent bonds to the aryl groups. The mesogens assemble in columnar stacks ranging from soft crystals to rectangular and hexagonal columnar liquid crystals, revealed by polarized optical microscopy, differential scanning calorimetry, X-ray scattering and modelling. The stability of the mesophases is crucially influenced by the binding mode of the arylcarboxy guest building blocks. The origin of the variation in clearing temperature is unravelled by modelling, cohesive energy density considerations and solid-state NMR spectroscopy. The control over the transition temperature is important for the formation of aligned thin films and thus for potential applications.

  13. Controlling enzymatic activity and kinetics in swollen mesophases by physical nano-confinement.

    PubMed

    Sun, Wenjie; Vallooran, Jijo J; Zabara, Alexandru; Mezzenga, Raffaele

    2014-06-21

    Bicontinuous lipid cubic mesophases are widely investigated as hosting matrices for functional enzymes to build biosensors and bio-devices due to their unique structural characteristics. However, the enzymatic activity within standard mesophases (in-meso) is severely hindered by the relatively small diameter of the mesophase aqueous channels, which provide only limited space for enzymes, and restrict them into a highly confined environment. We show that the enzymatic activity of a model enzyme, horseradish peroxidase (HRP), can be accurately controlled by relaxing its confinement within the cubic phases' water channels, when the aqueous channel diameters are systematically swollen with varying amount of hydration-enhancing sugar ester. The in-meso activity and kinetics of HRP are then systematically investigated by UV-vis spectroscopy, as a function of the size of the aqueous mesophase channels. The enzymatic activity of HRP increases with the swelling of the water channels. In swollen mesophases with water channel diameter larger than the HRP size, the enzymatic activity is more than double that measured in standard mesophases, approaching again the enzymatic activity of free HRP in bulk water. We also show that the physically-entrapped enzymes in the mesophases exhibit a restricted-diffusion-induced initial lag period and report the first observation of in-meso enzymatic kinetics significantly deviating from the normal Michaelis-Menten behaviour observed in free solutions, with deviations vanishing when enzyme confinement is released by swelling the mesophase.

  14. Nanoconfinement crystallization of frustrated alkyl groups: crossover of mesophase to crystalline structure.

    PubMed

    Shi, Haifeng; Wang, Haixia; Xin, John H; Zhang, Xingxiang; Wang, Dujin

    2011-04-07

    Crossover of mesophase to crystalline structure in the nanoconfinement crystallization process of frustrated side groups elucidates the critical crystal thickness d(c) or the length scale of side groups, which defines the transition process from mesophase (hexagonal and monoclinic phase) to crystalline phase (orthorhombic phase) of confined CH(2) sequences in a given crystal size restriction.

  15. Magnetic alignment of mesophase pitch-based carbon fibers

    NASA Astrophysics Data System (ADS)

    Matthews, M. J.; Dresselhaus, M. S.; Dresselhaus, G.; Endo, M.; Nishimura, Y.; Hiraoka, T.; Tamaki, N.

    1996-07-01

    Mesophase pitch-based carbon fibers (MPCFs) have recently been developed for use as high performance anode materials in Li ion secondary batteries, having a microscopic as well as macroscopic structure especially suitable for Li storage. Because of the highly anisotropic diamagnetic moment observed between 50 and 310 K in pristine milled MPCF segments, they can easily be oriented parallel to an applied magnetic field, as observed by scanning electron microscopy. A simple model is proposed to explain both the observed alignment of undoped fibers and the suppression of alignment in B-doped MPCFs for relatively small applied magnetic fields, because of their smaller diamagnetic moment.

  16. Influence of powder properties on the sintering of polyaromatic mesophases to high-strength isotropic graphite

    SciTech Connect

    Braun, M.; Gschwindt, A.; Hoffmann, W.R.

    1995-09-01

    The paper reviews the state of the art in sintering of polyaromatic mesophase powders to high-strength isotropic carbons and graphites. Synthesis of mesophase pitches from different precursor materials (petroleum- and coal tar pitch) using a net thermal or a catalyzed process, the preparation of mesophase powders from mesophase pitches and the influence of the powder properties on the sintering are discussed. Special attention is given to the role of thermoplasticity and the particle size of the mesophase powder as key properties for the production of high-strength carbons and graphites. After a graphitization treatment, isotropic graphites with a flexural strength of 160 MPa can be obtained, a value which probably represents an upper limit.

  17. Effect of sodium diclofenac loads on mesophase components and structure.

    PubMed

    Efrat, Rivka; Shalev, Deborah E; Hoffman, Roy E; Aserin, Abraham; Garti, Nissim

    2008-07-15

    We studied the effect of a model electrolytic drug on intermolecular interactions, conformational changes, and phase transitions in structured discontinuous cubic QL lyotropic liquid crystals. These changes were due to competition with hydration of the lipid headgroups. Structural changes of the phase induced by solubilization loads of sodium diclofenac (Na-DFC) were investigated by directly observing the water, ethanol, and Na-DFC components of the resulting phases using 2H and 23Na NMR. Na-DFC interacted with the surfactant glycerol monoolein (GMO) at the interface while interfering with the mesophase curvature and also competed with hydration of the surfactant headgroups. Increasing quantities of solubilized Na-DFC promoted phase transitions from cubic phase (discontinuous (QL) and bicontinuous (Q)) into lamellar structures and subsequently into a disordered lamellar phase. Quadrupolar coupling of deuterated ethanol by 2H NMR showed that it is located near the headgroups of the lipid and apparently is hydrogen bonded to the GMO headgroups. A phase transition between two lamellar phases (L alpha to L alpha*) was seen by 23Na NMR of Na-DFC at a concentration where the characteristics of the drug change from kosmotropic to chaotropic. These findings show that loads of solubilized drug may affect the structure of its vehicle and, as a result, its transport across skin-blood barriers. The structural changes of the mesophase may also aid controlled drug delivery.

  18. Lysozyme entrapped within reverse hexagonal mesophases: physical properties and structural behavior.

    PubMed

    Mishraki, Tehila; Libster, Dima; Aserin, Abraham; Garti, Nissim

    2010-01-01

    A model protein (lysozyme) was incorporated into monoolein-based reverse hexagonal (H(II)) mesophase and its structure effects were characterized by small angle X-ray scattering, ATR-FTIR spectroscopy, and rheological measurements. Modifications in molecular organization of the H(II) mesophases as well as the conformational stability of lysozyme (LSZ) as a function of pH and denaturating agent (urea) were clarified. Up to 3 wt.% LSZ can be solubilized into the H(II). The vibration FTIR analysis revealed that LSZ interacted with OH groups of glycerol monooleate (GMO) in the outer interface region, resulting in strong hydrogen bonding between the surfactant and its environment. Simultaneously, the decrease in the hydrogen-bonded carbonyl population of GMO was monitored, indicating dehydration of the monoolein carbonyls. These molecular interactions yielded a minor decrease in the lattice parameter of the systems, as detected by small angle X-ray scattering. Furthermore, LSZ was crystallized within the medium of the hexagonal structures in a single crystal form. The alpha-helix conformation of lysozyme was stabilized at high pH conditions, demonstrating greater helical structure content, compared to D(2)O solution. Moreover, the hexagonal phase decreased the unfavorable alpha-->beta transition in lysozyme, thereby increasing the stability of the protein under chemical denaturation. The rheological behavior of the hexagonal structures varied with the incorporation of LSZ, reflected in stronger elastic properties and pronounced solid-like response of the systems. The hydrogen bonding enhancement in the interface region of the structures was most likely responsible for these phenomena. The results of this study provided valuable information on the use of hexagonal systems as a carrier for incorporation and stabilization of proteins for various applications.

  19. HIV-TAT enhances the transdermal delivery of NSAID drugs from liquid crystalline mesophases.

    PubMed

    Cohen-Avrahami, Marganit; Shames, Alexander I; Ottaviani, M Francesca; Aserin, Abraham; Garti, Nissim

    2014-06-12

    Sodium diclofenac (Na-DFC) and celecoxib (CLXB) are common nonsteroidal anti-inflammatory (NSAID) drugs which suffer from poor bioavailability and severe side effects when consumed orally, and their transdermal delivery might present important advantages. In this study, the drugs were solubilized in cubic and lamellar mesophases as transdermal delivery vehicles, and a cell-penetrating peptide, HIV-TAT (TAT), was examined as a skin penetration enhancer. SD-NMR, ATR-FTIR, and EPR measurements revealed that, in the cubic mesophase (which is rich in water content), TAT populates the aqueous cores and binds water, while in the dense lamellar system (with the lower water content) TAT is bound also to the glycerol monooleate (GMO) and increases the microviscosity and the order degree. TAT secondary structure in the cubic system was found to be a random coil while once it was embedded in the closely packed lamellar system it transforms to a more ordered compact state of β-turns arranged around the GMO headgroups. TAT remarkably increased the diffusion of Na-DFC and CLXB from the cubic systems by 6- and 9-fold enhancement, respectively. TAT effect on drug diffusion from the lamellar systems was limited to an increase of 1.3- and 1.7-fold, respectively. The dense packing and strong binding in the lamellar phase led to slow diffusion rates and slower drug release in controlled pattern. These effects of the chemical composition and vehicle geometry on drug diffusion are demonstrated with the impacts of TAT which can be specifically utilized for controlling skin delivery of drugs as required.

  20. Controlling enzymatic activity and kinetics in swollen mesophases by physical nano-confinement

    NASA Astrophysics Data System (ADS)

    Sun, Wenjie; Vallooran, Jijo J.; Zabara, Alexandru; Mezzenga, Raffaele

    2014-05-01

    Bicontinuous lipid cubic mesophases are widely investigated as hosting matrices for functional enzymes to build biosensors and bio-devices due to their unique structural characteristics. However, the enzymatic activity within standard mesophases (in-meso) is severely hindered by the relatively small diameter of the mesophase aqueous channels, which provide only limited space for enzymes, and restrict them into a highly confined environment. We show that the enzymatic activity of a model enzyme, horseradish peroxidase (HRP), can be accurately controlled by relaxing its confinement within the cubic phases' water channels, when the aqueous channel diameters are systematically swollen with varying amount of hydration-enhancing sugar ester. The in-meso activity and kinetics of HRP are then systematically investigated by UV-vis spectroscopy, as a function of the size of the aqueous mesophase channels. The enzymatic activity of HRP increases with the swelling of the water channels. In swollen mesophases with water channel diameter larger than the HRP size, the enzymatic activity is more than double that measured in standard mesophases, approaching again the enzymatic activity of free HRP in bulk water. We also show that the physically-entrapped enzymes in the mesophases exhibit a restricted-diffusion-induced initial lag period and report the first observation of in-meso enzymatic kinetics significantly deviating from the normal Michaelis-Menten behaviour observed in free solutions, with deviations vanishing when enzyme confinement is released by swelling the mesophase.Bicontinuous lipid cubic mesophases are widely investigated as hosting matrices for functional enzymes to build biosensors and bio-devices due to their unique structural characteristics. However, the enzymatic activity within standard mesophases (in-meso) is severely hindered by the relatively small diameter of the mesophase aqueous channels, which provide only limited space for enzymes, and restrict them

  1. An investigation of the kinetics of the mesophase transformations in petroleum pitch by the ESR method

    SciTech Connect

    Samoilov, V.M.; Frolov, V.I.; Kotosonov, A.S.; Ostronov, B.G.; Rumyantsev, S.M.

    1983-01-01

    The amount of ..cap alpha../sub 1/ fraction, the concentration of paramagnetic centers, and the width of the line of the ESR signal have been determined for samples of mesophase pitches obtained by treating an initial petroleum pitch at 400-440/sup 0/C. The applicability of the ESR method for studying the kinetics and mechanism of the process of mesophase transformations has been shown. From the change in the parameters studied the rate constants and activation energies of the processes of the formation and growth of the aromatic regions of polyconjugation and of the accumulation of mesophase have been calculated.

  2. Method for producing mesophase-containing pitch by using carrier gas

    SciTech Connect

    Watanabe, M.

    1984-12-11

    A method for producing a mesophase-containing pitch from petroleum pitch or coal tar pitch is disclosed. According to this method volatile distillate fractions, which are harmful to mesophase formation and present originally in the raw material pitch or formed as by-product during heat treatment time are driven off by using a carrier gas at a temperature of 360/sup 0/ to 450/sup 0/ C. in order to shorten the overall heat treatment time and advance the mesophase formation smoothly by the increase of stirring effect.

  3. The Significant Structure Theory Applied to a Mesophase System

    PubMed Central

    Ma, Shao-mu; Eyring, H.

    1975-01-01

    The significant structure theory of liquids is extended to the mesophase system with p-azoxyanisole as an example. This compound has two different structures, a nematic phase and an isotropic phase, in its liquid state. In this study the nematic phase is treated as subject to a second volume and temperature-dependent degeneracy formally like that due to melting. The isotropic phase is treated as a normal liquid. The specific heat, thermal expansion coefficient, compressibility, volume, entropy of transitions, and heat of transitions are calculated and compared to the observed values. This analysis differs from previous ones in including the volume dependence as well as the temperature dependence in one explicit expression for the Helmholtz free energy. PMID:16592217

  4. Preparation of mesophase pitch by aromatics-rich distillate of naphthenic vacuum gas oil.

    PubMed

    Li, Ming; Liu, Dong; Du, Hui; Li, Qinyin; Hou, Xulian; Ye, Jiashun

    Two aromatics-rich distillates R1 and R2 with different properties from naphthenic base vacuum gas oil were used for preparing mesophase pitch through high-pressure thermal treatment. (1)H-NMR, FT-IR and VPO were employed to characterize the structural parameters of the raw materials. The products' optical texture and molecular structure were analyzed by polarized light optical microscopy, (1)H-NMR, FT-IR and XRD. The effect of raw materials' structure on the formation of mesophase pitch was discussed. The results showed that the structure of the raw material had an important effect on the formation of mesophase pitch. The raw material R2 with higher aromaticity, more naphthenic structure and less alkyl side chains was easy to form mesophase pitch with large-domains optical texture, lower softening point and more ordered crystal structure.

  5. An amorphous mesophase generated by thermal annealing for high-performance organic photovoltaic devices.

    PubMed

    Tanaka, Hideyuki; Abe, Yoko; Matsuo, Yutaka; Kawai, Junya; Soga, Iwao; Sato, Yoshiharu; Nakamura, Eiichi

    2012-07-10

    Thermal annealing of a p-i-n organic photovoltaic device containing a crystalline benzoporphyrin donor and solvated crystals of a silylmethylfullerene acceptor increases the device performance at a temperature where partial desolvation of the acceptor produces an amorphous mesophase. This suggests that the mesophase improves the hierarchical ordering of the materials, that is, the morphology of the n-layer and the interfacial contact and, hence, the carrier generation efficiency at the donor-acceptor interface.

  6. Influence of the counteranion on the ability of 1-dodecyl-3-methyltriazolium ionic liquids to form mesophases

    DOE PAGES

    Stappert, Kathrin; Unal, Derya; Spielberg, Eike T.; ...

    2014-11-25

    The influence of the counteranion on the ability of the mesogenic cation 1-methyl-3-dodecyl-triazolium to form mesophases is explored. To that avail, salts of the cation with anions of different size, shape, and hydrogen bonding capability such as Cl–, Br–, I–, I3–, PF6–, and Tf2N– [bis(trifluorosulfonyl)amide] were synthesized and characterized. The crystal structures of the bromide, the iodide, and the triiodide reveal that the cations form bilayers with cations oriented in opposite directions featuring interdigitated alkyl tails. Within the layers, the cations are separated by anions. The rod-shaped triiodide anion forces the triazolium cation to align with it in this crystalmore » structure but due to its space requirement reduces the alkyl chain interdigitation which prevents the formation of a mesophase. Rather the compound transforms directly from a crystalline solid to an (ionic) liquid like the analogous bis(trifluorosulfonyl)amide. In contrast, the simple halides and the hexafluorophosphate form liquid crystalline phases. As a result, their clearing points shift with increasing anion radius to lower temperatures.« less

  7. Influence of the counteranion on the ability of 1-dodecyl-3-methyltriazolium ionic liquids to form mesophases

    SciTech Connect

    Stappert, Kathrin; Unal, Derya; Spielberg, Eike T.; Mudring, Anja -Verena

    2014-11-25

    The influence of the counteranion on the ability of the mesogenic cation 1-methyl-3-dodecyl-triazolium to form mesophases is explored. To that avail, salts of the cation with anions of different size, shape, and hydrogen bonding capability such as Cl, Br, I, I3, PF6, and Tf2N [bis(trifluorosulfonyl)amide] were synthesized and characterized. The crystal structures of the bromide, the iodide, and the triiodide reveal that the cations form bilayers with cations oriented in opposite directions featuring interdigitated alkyl tails. Within the layers, the cations are separated by anions. The rod-shaped triiodide anion forces the triazolium cation to align with it in this crystal structure but due to its space requirement reduces the alkyl chain interdigitation which prevents the formation of a mesophase. Rather the compound transforms directly from a crystalline solid to an (ionic) liquid like the analogous bis(trifluorosulfonyl)amide. In contrast, the simple halides and the hexafluorophosphate form liquid crystalline phases. As a result, their clearing points shift with increasing anion radius to lower temperatures.

  8. HII mesophase as a drug delivery system for topical application of methyl salicylate.

    PubMed

    Liang, Xin; Chen, Yu-Lin; Jiang, Xiao-Jing; Wang, Sheng-Mei; Zhang, Ji-Wen; Gui, Shuang-Ying

    2017-03-30

    The main objective of this study was to develop reversed hexagonal (HII) mesophase for transdermal delivery of methyl salicylate. The formulation was prepared, characterized and evaluated for its skin penetration in vitro and skin retention in vivo. Preliminary pharmacodynamics and skin irritation were also investigated. The formulation was identified as hexagonal structure. In vitro study exhibited that HII mesophase enhanced the skin permeation by delivering 2.61 times more methyl salicylate than the commercially available cream. Meanwhile, HII mesophase presented higher bioavailability as AUC(0-24) and AUC(0-∞) were 32.894μg·mL(-1) and 32.935μg·mL(-1) respectively, while the cream were 12.791μg·mL(-1) and 12.970μg·mL(-1). Preliminary pharmacodynamics studies demonstrated that HII mesophase possessed anti-inflammatory and analgesic effects for inhibiting paw edema, granuloma and pain. MeSa HII mesophase showed no skin irritation on the normal rat skin. Thus, HII mesophase was considered as an effective delivery system for MeSa.

  9. Supercritical fluid extraction: Preparing a superior mesophase precursor for carbon fibers. Final report

    SciTech Connect

    Thies, M.C.

    1994-08-01

    Supercritical fluid (SCF) extraction is being investigated for the production of mesophase pitch, the liquid-crystalline precursor for the manufacture of high-performance carbon fibers. The mesophase pitch is produced by fractionation of an isotropic petroleum pitch with supercritical toluene in a region of liquid-liquid equilibrium that exists at pressures above 40 bar. Dramatic improvements in the reliability of the apparatus have recently been made, and mesophase pitch can now be produced on a routine basis. An experimental program was conducted to explore the effects of temperature, solvent-to-pitch (S/P) ratio, and solvent solubility parameter on the properties of the mesophase pitch produced. Temperatures of 320 and 360 deg C, solubility parameters of 3.7 and 5.0 (cal/cc)(1/2), and S/P ratios of 2.5 and 3.5 were chosen to conform to a two-level, augmented factorial experiment. A linear model correlated the data to a high degree of certainty. Results indicate that the authors can adjust SCF operating conditions and tailor-make a mesophase pitch for a given end use. They have discovered a semitheoretical method for predicting a priori the softening point and yield of mesophase pitch for a given set of SCF operating conditions. The SCF extraction process can be represented on a pseudoternary phase diagram, and good estimates of product yields and softening points can be made from a limited experimental data measured at other conditions.

  10. Enzyme Kinetics in Liquid Crystalline Mesophases: Size Matters, But Also Topology.

    PubMed

    Sun, Wenjie; Vallooran, Jijo J; Mezzenga, Raffaele

    2015-04-21

    Lyotropic liquid crystalline systems (LLCs) are excellent immobilizing carriers for enzymes, due to their biocompatibility and well-defined pore nanostructure. Here we show that the liquid crystalline mesophase topology can greatly influence the enzymatic activity in a typical peroxidase (Horseradish peroxidase, HRP) enzymatic reaction. Enzyme kinetics was investigated in different LLC mesophases based on monolinolein, with varying symmetries and dimensions such as the 1D cylindrical inverse hexagonal phase (HII), the 2D planar lamellar phase (Lα), and two 3D bicontinuous cubic phases of double diamond (Pn3m) and gyroid (Ia3d) space groups. As expected, the mesophase with largest water channel size shows highest activity, regardless of the topology. Interestingly, however, when mesophases with different topologies have the same water channel size, then the topology plays the dominant role, and the enzyme showed the highest activity in the 3D tetra-fold connected Pn3m, followed by the Ia3d with trifold connectivity, and finally the 1D HII phase. This study demonstrates that the enzymatic activity in LLC mesophases depends on both the water channel size and the topology of the mesophase.

  11. Mesophases in polyethylene, polypropylene, and poly(1-butene)

    SciTech Connect

    Androsch, Rene J; Di Lorenzo, Maria; Schick, Christoph; Wunderlich, Bernhard {nmn}

    2010-01-01

    This paper contains new views about the amorphous and partially ordered phases of the three polymers listed in the title. The discussion is based on information on structure, thermodynamic stability, and large-amplitude molecular motion. Polyethylene is the basic backbone of all alkene polymers, and the other two are the first members of the vinyl polymers which have stereospecifically placed alkyl side chains. Their multiphase structures consist of metastable crystals, mesophases, and surrounding rigid and mobile amorphous fractions. All these phases have sizes ranging from micrometer dimensions down to nanometers. Besides the phase structures, information about the molecular coupling between the phases must be considered. Depending on temperature, the polymer phases can vary from solid (rigid) to liquid (mobile). New knowledge is also gained by cross-comparison of the title polymers. The experimental information was gained from (a) various forms of slow, fast, and temperature-modulated thermal analysis to identify equilibrium and non-equilibrium states, (b) measurement of structure and morphology at various length scales, and (c) tracing of the large-amplitude molecular motion, the kinetics of order/disorder changes, and the liquid/solid transitions (glass transitions). It is shown that much more needs to be known about the various phases and their coupling to characterize a given polymer and to fine-tune its properties for a given application.

  12. DNA mesophases induced by spermidine: structural properties and biological implications.

    PubMed Central

    Pelta, J; Durand, D; Doucet, J; Livolant, F

    1996-01-01

    Conditions of formation of DNA aggregates by the addition of spermidine were determined with 146 base pair DNA fragments as a function of spermidine and NaCl concentration. Two different phases of spermidine-DNA complexes are obtained: a cholesteric liquid crystalline phase with a large helical pitch, with interhelix distances ranging from 31.6 to 32.6 A, and a columnar hexagonal phase with a restricted fluidity in which DNA molecules are more closely packed (29.85 +/- 0.05 A). In both phases, the DNA molecule retains its B form. These phases are always observed in equilibrium with the dilute isotropic solution, and their phase diagram is defined for a DNA concentration of 1 mg/ml. DNA liquid crystalline phases induced by spermidine are compared with the DNA mesophases already described in concentrated solutions in the absence of spermidine. We propose that the liquid crystalline character of the spermidine DNA complexes is involved in the stimulation of the functional properties of the DNA reported in numerous experimental articles, and we discuss how the nature of the phase could regulate the degree of activity of the molecule. Images FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 8 FIGURE 10 PMID:8804588

  13. Osmotically induced reversible transitions in lipid-DNA mesophases.

    PubMed

    Danino, Dganit; Kesselman, Ellina; Saper, Gadiel; Petrache, Horia I; Harries, Daniel

    2009-04-08

    We follow the effect of osmotic pressure on isoelectric complexes that self-assemble from mixtures of DNA and mixed neutral and cationic lipids. Using small angle x-ray diffraction and freeze-fracture cryo-electron microscopy, we find that lamellar complexes known to form in aqueous solutions can reversibly transition to hexagonal mesophases under high enough osmotic stress exerted by adding a neutral polymer. Using molecular spacings derived from x-ray diffraction, we estimate the reversible osmotic pressure-volume (Pi-V) work needed to induce this transition. We find that the transition free energy is comparable to the work required to elastically bend lipid layers around DNA. Consistent with this, the required work is significantly lowered by an addition of hexanol, which is known to soften lipid bilayers. Our findings not only help to resolve the free-energy contributions associated with lipid-DNA complex formation, but they also demonstrate the importance that osmotic stress can have to the macromolecular phase geometry in realistic biological environments.

  14. Mesophase stabilization in ionic liquid crystals through pairing equally shaped mesogenic cations and anions

    SciTech Connect

    Stappert, Kathrin; Lipinski, Gregor; Kopiec, Gabriel; Spielberg, Eike T.; Mudring, Anja -Verena

    2015-07-23

    The synthesis and properties of a set of novel ionic liquid crystals with congruently shaped cations and anions are reported to check whether pairing mesogenic cations with mesogenic anions leads to a stabilization of a liquid crystalline phase. To that avail 1-alkyl-3-methyl-triazolium cations with an alkyl chain length of 10, 12, and 14 carbon atoms have been combined with p-alkyloxy-benzenesulfonate anions with different alkyl chain lengths (n = 10, 12, and 14). The corresponding triazolium iodides have been synthesized as reference compounds where the cation and anion have strong size and shape mismatch. The mesomorphic behavior of all compounds is studied by differential scanning calorimetry and polarizing optical microscopy. All compounds except 1-methyl-3-decyltriazolium iodide, which qualifies as an ionic liquid, are thermotropic ionic liquid crystals. All other compounds adopt smectic A phases. As a result, a comparison of the thermal phase behavior of the 1-methyl-3-decyltriazolium bromides to the corresponding p-alkoxy-benzensulfonates reveals that definitely the mesophase is stabilized by pairing the rod-shaped 1-alkyl-3-methyltriazolium cation with a rod-like anion of similar size.

  15. Mesophase stabilization in ionic liquid crystals through pairing equally shaped mesogenic cations and anions

    DOE PAGES

    Stappert, Kathrin; Lipinski, Gregor; Kopiec, Gabriel; ...

    2015-07-23

    The synthesis and properties of a set of novel ionic liquid crystals with congruently shaped cations and anions are reported to check whether pairing mesogenic cations with mesogenic anions leads to a stabilization of a liquid crystalline phase. To that avail 1-alkyl-3-methyl-triazolium cations with an alkyl chain length of 10, 12, and 14 carbon atoms have been combined with p-alkyloxy-benzenesulfonate anions with different alkyl chain lengths (n = 10, 12, and 14). The corresponding triazolium iodides have been synthesized as reference compounds where the cation and anion have strong size and shape mismatch. The mesomorphic behavior of all compounds ismore » studied by differential scanning calorimetry and polarizing optical microscopy. All compounds except 1-methyl-3-decyltriazolium iodide, which qualifies as an ionic liquid, are thermotropic ionic liquid crystals. All other compounds adopt smectic A phases. As a result, a comparison of the thermal phase behavior of the 1-methyl-3-decyltriazolium bromides to the corresponding p-alkoxy-benzensulfonates reveals that definitely the mesophase is stabilized by pairing the rod-shaped 1-alkyl-3-methyltriazolium cation with a rod-like anion of similar size.« less

  16. An X-ray transparent microfluidic platform for screening of the phase behavior of lipidic mesophases.

    PubMed

    Khvostichenko, Daria S; Kondrashkina, Elena; Perry, Sarah L; Pawate, Ashtamurthy S; Brister, Keith; Kenis, Paul J A

    2013-09-21

    Lipidic mesophases are a class of highly ordered soft materials that form when certain lipids are mixed with water. Understanding the relationship between the composition and the microstructure of mesophases is necessary for fundamental studies of self-assembly in amphiphilic systems and for applications, such as the crystallization of membrane proteins. However, the laborious formulation protocol for highly viscous mesophases and the large amounts of material required for sample formulation are significant obstacles in such studies. Here we report a microfluidic platform that facilitates investigations of the phase behavior of mesophases by reducing sample consumption 300-fold, and automating and parallelizing sample formulation. The mesophases were formulated on-chip using less than 80 nL of material per sample and their microstructure was analyzed in situ using small-angle X-ray scattering (SAXS). The 220 μm-thick X-ray compatible platform was comprised of thin polydimethylsiloxane (PDMS) layers sandwiched between cyclic olefin copolymer (COC) sheets. Uniform mesophases were prepared using an active on-chip mixing strategy coupled with periodic cooling of the sample to reduce viscosity. We validated the platform by preparing and analyzing mesophases of the lipid monoolein (MO) mixed with aqueous solutions of different concentrations of β-octylglucoside (βOG), a detergent frequently used in membrane protein crystallization. Four samples were prepared in parallel on chip, by first metering and automatically diluting βOG to obtain detergent solutions of different concentration, then metering MO, and finally mixing by actuation of pneumatic valves. Integration of detergent dilution and subsequent mixing significantly reduced the number of manual steps needed for sample preparation. Three different types of mesophases typical for MO were successfully identified in SAXS data from on-chip samples. Microstructural parameters of identical samples formulated in

  17. Spectroscopic characterizations of a mixed surfactant mesophase and its application in materials synthesis

    NASA Astrophysics Data System (ADS)

    Liu, Limin

    A viscous lyotropic crystalline mesophase containing bis (2-ethylhexyl) sodium sulfosuccinate (AOT), alpha-phosphatidylcholine (lecithin), with comparable volume fractions of isooctane and water was characterized by Fourier-transform 31P and 1H nuclear magnetic resonance (NMR) spectroscopy. Shear alignment on the reverse hexagonal mesophase was reflected through both 31P NMR and 1H NMR spectra. A complicated 31P spectrum was observed as a result of superposition of chemical shifts according to the distribution of crystalline domains prior to shear. The initially disordered samples with polydomain structures became macroscopically aligned after Couette shear and the alignment retained for a long period of time. 31P NMR chemical shift anisotropy characteristics were used to elucidate orientation of the hexagonal phase. Interestingly, 1H NMR of the water, methyl and methylene groups exhibited spectral changes upon shear alignment closely corresponding with that of 31P NMR spectra. A reverse hexagonal to lamellar phase transition was manifested as an expanding of the expressed 31P NMR chemical shift anisotropy and an apparent reversal of the powder pattern with increasing water content and/or temperature. Correspondingly, 1H NMR spectra also experienced a spectral pattern transition as the water content or temperature was increased. These observations complement the findings of mesophase alignment obtained using small angle neutron scattering (SANS) and imply that 31P and 1H NMR spectroscopy can be used as probes to define microstructure and monitor orientation changes in this binary surfactant system. This is especially beneficial if these mesophases are used as templates for materials synthesis. The mesophase retains its alignment for extended periods allowing materials synthesis to be decoupled from the application of shear. Highly aligned string-like silica nanostructures were obtained through templated synthesis in the columnar hexagonal structure of the viscous

  18. Controlling molecular transport and sustained drug release in lipid-based liquid crystalline mesophases.

    PubMed

    Zabara, Alexandru; Mezzenga, Raffaele

    2014-08-28

    Lipid-based lyotropic liquid crystals, also referred to as reversed liquid crystalline mesophases, such as bicontinuous cubic, hexagonal or micellar cubic phases, have attracted deep interest in the last few decades due to the possibility of observing these systems at thermodynamic equilibrium in excess water conditions. This becomes of immediate significance for applications in the colloidal environment, such as in the food, cosmetic and pharmaceutical arenas. One possible application regarded as very promising is that of controlled delivery of functional ingredients. Different crystallographic structures of the lipid mesophase give access to different diffusion coefficients and distinct diffusion modes. It becomes thus crucial to engineer the space group of the mesophase in a controlled way, and ideally, in a stimuli-responsive manner. In this article we review the state of the art on diffusion and molecular transport in lipid-based mesophases and we discuss recent contributions to the controlled delivery of molecules and colloids through these systems. In particular we focus on the different available strategies relying on either endogenous or exogenous stimuli to induce changes in the symmetry and transport properties of lipid-based mesophases and we discuss the impact and implications this may have on controlled drug delivery.

  19. Dynamics of edge dislocations in a sheared lamellar mesophase

    NASA Astrophysics Data System (ADS)

    Kumaran, V.

    2013-10-01

    The dynamics and interactions of edge dislocations in a nearly aligned sheared lamellar mesophase is analysed to provide insights into the relationship between disorder and rheology. First, the mesoscale permeation and momentum equations for the displacement field in the presence of external forces are derived from the model H equations for the concentration and momentum field. The secondary flow generated due to the mean shear around an isolated defect is calculated, and the excess viscosity due to the presence of the defect is determined from the excess energy dissipation due to the secondary flow. The excess viscosity for an isolated defect is found to increase with system size in the cross-stream direction as L3/2 for an isolated defect, though this divergence is cut-off due to interactions in a defect suspension. As the defects are sheared past each other due to the mean flow, the Peach-Koehler force due to elastic interaction between pairs of defects is found to cause no net displacement relative to each other as they approach from large separation to the distance of closest approach. The equivalent force due to viscous interactions is found to increase the separation for defects of opposite sign, and decrease the separation for defects of same sign. During defect interactions, we find that there is no buckling instability due to dilation of layers for systems of realistic size. However, there is another mechanism, which is the velocity difference generated across a slightly deformed bilayer due to the mean shear, which could result in the creation of new defects.

  20. The effect of dendrimer generations on the structure of Q(G) LLC mesophase and drug release.

    PubMed

    Bitan-Cherbakovsky, Liron; Aserin, Abraham; Garti, Nissim

    2014-10-01

    In this paper the cosolubilization of 2nd, 3rd, and 4th generations of polypropyleneimine (PPI: PPI-G2, -G3, and -G4) dendrimers with sodium diclofenac (Na-DFC) into reverse gyroid cubic (Q(G)) liquid crystals is reported. Structural properties and interactions of PPI dendrimers with and without the drug were studied using small-angle X-ray scattering, attenuated total reflected Fourier transform infrared (ATR-FTIR) spectroscopy, and differential scanning calorimetry (DSC) measurements. Incorporation of PPI-G2 (without Na-DFC) into Q(G) mesophase led to a decrease of 78Å in the lattice parameter. Solubilization of higher PPI generations, G3 and G4, led to increases in the lattice parameter to 57Å and 64Å, respectively. At 25wt%, each of the dendrimers caused a phase transition Q(G)→reverse hexagonal (HII). According to ATR-FTIR and DSC, the large lattice parameter values of G3 and G4 (relative to G2) embedment were assigned to their interactions with the carboxyl groups of GMO at the interface in comparison to the strong interaction of PPI-G2 with the water. Cosolubilization of Na-DFC with PPI-G2 revealed enlargement of the lattice parameter (of the new HII mesophase), while in the case of G3 and G4 systems no significant influence was seen with Na-DFC. The release of Na-DFC from Q(G) and HII systems was followed by UV-vis spectroscopy and revealed generation-dependence on drug release. As dendrimer generation increased, the cumulative drug release decreased.

  1. H(II) mesophase and peptide cell-penetrating enhancers for improved transdermal delivery of sodium diclofenac.

    PubMed

    Cohen-Avrahami, Marganit; Aserin, Abraham; Garti, Nissim

    2010-06-01

    This study develops a novel transdermal delivery vehicle for the enhanced delivery of sodium diclofenac (Na-DFC). The system utilizes the advantages of reversed hexagonal lyotropic liquid crystals (H(II)LC), combined with a peptide cell penetration enhancer (CPE), creating together an adaptable system that provides versatile options in the field of transdermal delivery. This enhancer peptide is based on a family of amphipatic peptides that exhibit improved membrane permeability. Franz permeation cell experiments revealed that the peptide enhancer (RALA) improved Na-DFC skin penetration of the liquid crystal 2.2-fold. We studied the structural effects of RALA solubilization on the H(II) mesophase. RALA acts as a chaotropic agent, interfering in the structure of the water, and causes a measurable swelling of the aqueous cylinders by 5A. Small angle X-ray scattering (SAXS) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) measurements reveal enhanced hydration of the glycerol monooleate (GMO) headgroups and a 6.5% increase in the fraction of non-freezable water resulting from RALA incorporation. RALA caused a gradual increase in the GMO effective headgroup area due to the hydration, leading eventually to a transform of the hexagonal structure towards a lamellar one. Circular dichroism and ATR-FTIR measurements showed a conservation of the peptide structure when incorporated into the H(II) mesophase. The combined H(II)LC-CPE systems can serve as high potential vehicles for a variety of drugs, as they can easily be modified by varying the composition and temperature, according to the required dose and delivery features.

  2. Broadening of mesophase temperature range induced by doping calamitic mesogen with banana-shaped mesogen

    NASA Astrophysics Data System (ADS)

    Cvetinov, Miroslav; Stojanović, Maja; Obadović, Dušanka; Vajda, Aniko; Fodor-Csorba, Katalin; Eber, Nandor

    2016-03-01

    We have investigated three binary mixtures composed of selected banana-shaped dopant in low concentrations and calamitic mesogen in high. Banana-shaped dopant forms a B7 phase, while the calamitic mesogen exhibit nematic and smectic SmA and SmC phases. The occurring mesophases have been identified by their optical textures. At dopant concentrations of 2.2 and 3.1 mol%, there is evident broadening of nematic and smectic SmA temperature ranges in respect to the pure calamitic compound. Yet, the mixture with dopant concentration of 7 mol% exhibits narrower temperature ranges of mesophases. Increasing dopant concentration caused lowering of all phase transitions temperatures (TI-N, TN-SmA, TSmA-SmC) in all investigated mixtures. Therefore, mixing classic calamitic compounds with novel banana-shaped compound in low concentrations is viable way to attain useful mesophase range for application in industry.

  3. The Dependency of Nematic and Twist-bend Mesophase Formation on Bend Angle

    PubMed Central

    Mandle, Richard J.; Archbold, Craig T.; Sarju, Julia P.; Andrews, Jessica L.; Goodby, John W.

    2016-01-01

    We have prepared and studied a family of cyanobiphenyl dimers with varying linking groups with a view to exploring how molecular structure dictates the stability of the nematic and twist-bend nematic mesophases. Using molecular modelling and 1D 1H NOESY NMR spectroscopy, we determine the angle between the two aromatic core units for each dimer and find a strong dependency of the stability of both the nematic and twist-bend mesophases upon this angle, thereby satisfying earlier theoretical models. PMID:27819300

  4. X-ray characterization of mesophases of human telomeric G-quadruplexes and other DNA analogues

    PubMed Central

    Yasar, Selcuk; Schimelman, Jacob B.; Aksoyoglu, M. Alphan; Steinmetz, Nicole F.; French, Roger H.; Parsegian, V. Adrian; Podgornik, Rudolf

    2016-01-01

    Observed in the folds of guanine-rich oligonucleotides, non-canonical G-quadruplex structures are based on G-quartets formed by hydrogen bonding and cation-coordination of guanosines. In dilute 5′-guanosine monophosphate (GMP) solutions, G-quartets form by the self-assembly of four GMP nucleotides. We use x-ray diffraction to characterize the columnar liquid-crystalline mesophases in concentrated solutions of various model G-quadruplexes. We then probe the transitions between mesophases by varying the PEG solution osmotic pressure, thus mimicking in vivo molecular crowding conditions. Using the GMP-quadruplex, built by the stacking of G-quartets with no covalent linking between them, as the baseline, we report the liquid-crystalline phase behaviors of two other related G-quadruplexes: (i) the intramolecular parallel-stranded G-quadruplex formed by the 22-mer four-repeat human telomeric sequence AG3(TTAG3)3 and (ii) the intermolecular parallel-stranded G-quadruplex formed by the TG4T oligonucleotides. Finally, we compare the mesophases of the G-quadruplexes, under PEG-induced crowding conditions, with the corresponding mesophases of the canonical duplex and triplex DNA analogues. PMID:27249961

  5. A narrow ESR signal and mesophase transformations in the heat treatment of coals and pitches

    SciTech Connect

    Farber, M.S.

    1982-01-01

    The author discusses changes in the EPR spectrum when coal, pitch and its fractions are heated directly in the spectrometer resonator. It is shown that the high temperature maximum of EPR signals is determined to a significant extent by the narrow signal. This suggests that the narrow signal spectrum is related to the mesophase structures during the synthesis process.

  6. Supramolecular structures and columnar mesophase induction in nondiscoid pyrazoles by complexation to rhodium(I).

    PubMed

    Giménez, Raquel; Elduque, Anabel; López, José Antonio; Barbera, Joaquín; Cavero, Emma; Lantero, Ignacio; Oro, Luis A; Serrano, José Luis

    2006-12-11

    Several new cis-[RhCl(CO)2(Ln)] complexes have been prepared using different polycatenar pyrazole ligands (Ln) in order to obtain columnar liquid crystalline arrangements. The topology of the ligand plays an essential role, and a mesophase is induced at room temperature from a nonmesogenic pyrazole only when it is symmetrically substituted with six decyloxy chains. The single-crystal structure of a methoxy-substituted analogue, 3,5-bis(3,4,5-trimethoxyphenyl)pyrazole, is formed by globular tetrameric structures held together by H-bonding. However, parallel dimers are present in the corresponding cis-chlorodicarbonylrhodium(I) complex, a situation that explains the induction of a columnar mesophase in the decyloxy-substituted complex. The XRD pattern of the mesophase is consistent with a hexagonal symmetry in which the columns are formed by molecules assembled in an antiparallel mode. The crystal-to-mesophase transition was also detected by spectroscopic techniques as a shift in the IR carbonyl stretching bands and the appearance of a charge-transfer band in the absorption spectrum with thermochromic behavior.

  7. X-ray characterization of mesophases of human telomeric G-quadruplexes and other DNA analogues

    NASA Astrophysics Data System (ADS)

    Yasar, Selcuk; Schimelman, Jacob B.; Aksoyoglu, M. Alphan; Steinmetz, Nicole F.; French, Roger H.; Parsegian, V. Adrian; Podgornik, Rudolf

    2016-06-01

    Observed in the folds of guanine-rich oligonucleotides, non-canonical G-quadruplex structures are based on G-quartets formed by hydrogen bonding and cation-coordination of guanosines. In dilute 5‧-guanosine monophosphate (GMP) solutions, G-quartets form by the self-assembly of four GMP nucleotides. We use x-ray diffraction to characterize the columnar liquid-crystalline mesophases in concentrated solutions of various model G-quadruplexes. We then probe the transitions between mesophases by varying the PEG solution osmotic pressure, thus mimicking in vivo molecular crowding conditions. Using the GMP-quadruplex, built by the stacking of G-quartets with no covalent linking between them, as the baseline, we report the liquid-crystalline phase behaviors of two other related G-quadruplexes: (i) the intramolecular parallel-stranded G-quadruplex formed by the 22-mer four-repeat human telomeric sequence AG3(TTAG3)3 and (ii) the intermolecular parallel-stranded G-quadruplex formed by the TG4T oligonucleotides. Finally, we compare the mesophases of the G-quadruplexes, under PEG-induced crowding conditions, with the corresponding mesophases of the canonical duplex and triplex DNA analogues.

  8. X-ray characterization of mesophases of human telomeric G-quadruplexes and other DNA analogues

    SciTech Connect

    Yasar, Selcuk; Schimelman, Jacob B.; Aksoyoglu, M. Alphan; Steinmetz, Nicole F.; French, Roger H.; Parsegian, V. Adrian; Podgornik, Rudolf

    2016-06-02

    We report that observed in the folds of guanine-rich oligonucleotides, non-canonical G-quadruplex structures are based on G-quartets formed by hydrogen bonding and cation-coordination of guanosines. In dilute 5'-guanosine monophosphate (GMP) solutions, G-quartets form by the self-assembly of four GMP nucleotides. We use x-ray diffraction to characterize the columnar liquid-crystalline mesophases in concentrated solutions of various model G-quadruplexes. We then probe the transitions between mesophases by varying the PEG solution osmotic pressure, thus mimicking in vivo molecular crowding conditions. Using the GMP-quadruplex, built by the stacking of G-quartets with no covalent linking between them, as the baseline, we report the liquid-crystalline phase behaviors of two other related G-quadruplexes: (i) the intramolecular parallel-stranded G-quadruplex formed by the 22-mer four-repeat human telomeric sequence AG3 (TTAG3)3 and (ii) the intermolecular parallel-stranded G-quadruplex formed by the TG(4)T oligonucleotides. Finally, we compare the mesophases of the G-quadruplexes, under PEG-induced crowding conditions, with the corresponding mesophases of the canonical duplex and triplex DNA analogues.

  9. X-ray characterization of mesophases of human telomeric G-quadruplexes and other DNA analogues

    DOE PAGES

    Yasar, Selcuk; Schimelman, Jacob B.; Aksoyoglu, M. Alphan; ...

    2016-06-02

    We report that observed in the folds of guanine-rich oligonucleotides, non-canonical G-quadruplex structures are based on G-quartets formed by hydrogen bonding and cation-coordination of guanosines. In dilute 5'-guanosine monophosphate (GMP) solutions, G-quartets form by the self-assembly of four GMP nucleotides. We use x-ray diffraction to characterize the columnar liquid-crystalline mesophases in concentrated solutions of various model G-quadruplexes. We then probe the transitions between mesophases by varying the PEG solution osmotic pressure, thus mimicking in vivo molecular crowding conditions. Using the GMP-quadruplex, built by the stacking of G-quartets with no covalent linking between them, as the baseline, we report the liquid-crystallinemore » phase behaviors of two other related G-quadruplexes: (i) the intramolecular parallel-stranded G-quadruplex formed by the 22-mer four-repeat human telomeric sequence AG3 (TTAG3)3 and (ii) the intermolecular parallel-stranded G-quadruplex formed by the TG(4)T oligonucleotides. Finally, we compare the mesophases of the G-quadruplexes, under PEG-induced crowding conditions, with the corresponding mesophases of the canonical duplex and triplex DNA analogues.« less

  10. High performance carbon fibers from mesophases produced by supercritical fluid extraction

    NASA Astrophysics Data System (ADS)

    Dauche, Franck Michel

    The purpose of this research is to investigate the potential of supercritical fluid extraction for the production of an improved precursor for the manufacture of high thermal conductivity carbon fibers. Mesophase pitch fractions were produced by the continuous fractionation of an isotropic petroleum-based pitch with supercritical toluene in a region of liquid-liquid equilibrium. A statistical experimental design was used to investigate a region of extraction operating conditions from which the fractions were expected to exhibit superior spinnability. Chemical and physical characterizations were performed on the fractions, and the results were used to explore the effect of the extraction conditions on the mesophase properties. DRIFT data were shown to be particularly useful for characterizing the chemical composition of the mesophase fractions produced, and GPC was successfully used to determine their molecular weight distribution. Two thermodynamic models based on the SAFT equation together with (1) the concepts of continuous thermodynamics (2) molecular weight information on the oligomeric nature of the feed pitch were used to correlate the measured results. By using three adjustable parameters, solvent compositions and molecular weight distributions in each phase were calculated. Although the oligomeric model is able to qualitatively represent trends observed in the data, it cannot as yet be used to quantitatively predict phase compositions. Based on the characterizations of the supercritically extracted mesophases produced, selected fractions were melt-spun into round- and ribbon-shaped fibers using a laboratory-scale melt-spinning apparatus. It was found that a relatively narrow window of mesophase properties and compositions allowed fiber making without off-gassing. For a given spinnable mesophase, wide angle X-ray diffraction was used on as-spun fibers produced over a wide range of spinning temperatures to evaluate their potential to yield, after proper heat

  11. Development of Direct and Optical Polarized Nuclear Magnetic Resonance (NMR) Methods for Characterization and Engineering of Mesophased Molecular Structures

    SciTech Connect

    Maxwell, R; Baumann, T; Taylor, B

    2002-01-29

    The development of NMR methods for the characterization of structure and dynamics in mesophase composite systems was originally proposed in this LDRD. Mesophase systems are organic/inorganic hybrid materials whose size and motional properties span the definition of liquids and solids, such as highly viscous gels or colloidal suspensions. They are often composite, ill defined, macromolecular structures that prove difficult to characterize. Mesophase materials are of broad scientific and programmatic interest and include composite load bearing foams, aerogels, optical coatings, silicate oligomers, porous heterogeneous catalysts, and nanostructured materials such as semiconductor quantum dot superlattices. Since mesophased materials and precursors generally lack long-range order they have proven to be difficult to characterize beyond local, shortrange order. NMR methods are optimal for such a task since NMR observables are sensitive to wide ranges of length (0-30{angstrom}) and time (10{sup -9}-10{sup 0}sec) scales. We have developed a suit of NMR methods to measure local, intermediate, and long range structure in a series of mesophase systems and have constructed correlations between NMR observables and molecular size, topology, and network structure. The goal of this research was the development of a strong LLNL capability in the characterization of mesophased materials by NMR spectroscopy that will lead to a capability in rational synthesis of such materials and a fundamental understanding of their structure-property relationships. We demonstrate our progress towards attaining this goal by presenting NMR results on four mesophased model systems.

  12. Mesoscopic structure and properties of liquid crystalline mesophase pitch and its transformation into carbon fiber.

    PubMed

    Mochida, Isao; Yoon, Seong-Ho; Korai, Yozo

    2002-01-01

    The history and present state of the art in the chemistry of mesophase pitch, which is an important precursor for carbon fiber and other high-performance industrial carbons, are reviewed relative to their structural properties. The structural concepts in both microscopic and macroscopic views are summarized in terms of the sp(2) carbon hexagonal plane as a basic unit common to graphitic materials, its planar stacking in clusters, and cluster assembly into microdomains and domains, the latter of which reflect the isochromatic unit of optical anisotropy. Such a series of structural units is described in a semiquantitative manner corresponding to the same units of graphitic materials, although the size and stacking height of the hexagonal planes (graphitic sheets) are very different. Mesophase pitch is a liquid crystal material whose basic structural concepts are maintained in the temperature range of 250 to 350 degrees C. The melt flow and thermal properties are related to its micro- and mesoscopic structure. The structure of mesophase-pitch-based carbon fiber of high tensile strength, modulus, and thermal conductivity has been formed through spinning, and has inherited the same structural concepts of mesophase pitch. Stabilization settles the structure in successive heat treatments up to 3000 degrees C. Carbonization and graphitization enable growth of the hexagonal planes and their stacking into units of graphite. Such growth is governed and controlled by the alignment of micro- and mesoscopic structures in the mesophase pitch, which define the derived carbon materials as nanostructural materials. Their properties are controlled by the nanoscopic units that are expected to behave as nanomaterials when appropriately isolated or handled.

  13. Changes in the microstructure and characteristics of carbon/carbon composites with mesophase mesocarbon microbeads added during graphitization

    SciTech Connect

    Hu, H.L.; Ko, T.H.; Ku, W.S.

    2005-12-05

    Carbon/carbon (C/C) composites were prepared from oxidative PAN fiber felts, a resol-type phenolic resin, and mesophase pitch derived from coal tar. In this study, the effects on mesocarbon microbeads (MCMBs), flexural strength, flexural moduli, electric conductivity, and thermal conductivity of C/C composites with a mesophase content ranging from 0 to 30 wt % were examined during pyrolysis. The results show that the C/C composite with the addition of 10-30 wt % mesophase had a higher density, greater stacking size, and higher preferred orientation than the C/C composites without any mesophase during heat treatment. These composites also exhibited an improvement in flexural strength from 19.7 to 30.3%. The flexural moduli of these composites with mesophase added increased by 15.1 to 31.3% compared to that with no mesophase added. These composites also showed improved electric conductivity, from 15.1 to 43.7%, and thermal conductivity, from 12 to 31.3%.

  14. Aligned nanostructured polymers by magnetic-field-directed self-assembly of a polymerizable lyotropic mesophase.

    PubMed

    Tousley, Marissa E; Feng, Xunda; Elimelech, Menachem; Osuji, Chinedum O

    2014-11-26

    Magnetic-field-directed assembly of lyotropic surfactant mesophases provides a scalable approach for the fabrication of aligned nanoporous polymers by templated polymerization. We develop and characterize a lyotropic liquid crystalline system containing hexagonally packed cylindrical micelles of a polymerizable surfactant in a polymerizable solvent. The system exhibits negative magnetic anisotropy, resulting in the degenerate alignment of cylindrical micelles perpendicular to the magnetic field. Sample rotation during field alignment is used to effectively break this degeneracy and enable the production of uniformly well-aligned mesophases. High-fidelity retentions of the hexagonal structure and alignment were successfully achieved in polymer films produced upon UV exposure of the reactive system. The success of this effort provides a route for the fabrication of aligned nanoporous membranes suitable for highly selective separations, sensing, and templated nanomaterial synthesis.

  15. Magnetic materials based on iron dispersed in graphitic matrices II. High temperatures and mesophase pitch

    NASA Astrophysics Data System (ADS)

    Dyakonov, Alexander J.; Jack McCormick, B.; Kahol, Pawan K.; Hamdeh, Hussein H.

    1997-03-01

    Ferromagnetic materials based on iron incorporated into pitch were synthesized, and characterized by magnetic methods (Faraday), Mössbauer spectroscopy, SEM, and XRD. A graphitic-type structure was observed to form at 350-1650°C. The important role of a mesophase structure of a pitch-precursor in the iron carbonyl absorption and anisotropic structure of the resulting iron containing material was found.

  16. Crystallizing membrane proteins for structure-function studies using lipidic mesophases.

    PubMed

    Caffrey, Martin

    2011-06-01

    The lipidic cubic phase method for crystallizing membrane proteins has posted some high-profile successes recently. This is especially true in the area of G-protein-coupled receptors, with six new crystallographic structures emerging in the last 3½ years. Slowly, it is becoming an accepted method with a proven record and convincing generality. However, it is not a method that is used in every membrane structural biology laboratory and that is unfortunate. The reluctance in adopting it is attributable, in part, to the anticipated difficulties associated with handling the sticky viscous cubic mesophase in which crystals grow. Harvesting and collecting diffraction data with the mesophase-grown crystals is also viewed with some trepidation. It is acknowledged that there are challenges associated with the method. However, over the years, we have worked to make the method user-friendly. To this end, tools for handling the mesophase in the pico- to nano-litre volume range have been developed for efficient crystallization screening in manual and robotic modes. Glass crystallization plates have been built that provide unparalleled optical quality and sensitivity to nascent crystals. Lipid and precipitant screens have been implemented for a more rational approach to crystallogenesis, such that the method can now be applied to a wide variety of membrane protein types and sizes. In the present article, these assorted advances are outlined, along with a summary of the membrane proteins that have yielded to the method. The challenges that must be overcome to develop the method further are described.

  17. Interface tuning and stabilization of monoglyceride mesophase dispersions: Food emulsifiers and mixtures efficiency.

    PubMed

    Serieye, Sébastien; Méducin, Fabienne; Milošević, Irena; Fu, Ling; Guillot, Samuel

    2017-06-15

    Several food surfactants were examined as possible efficient emulsifiers for liquid crystalline monolinolein-based particles and as alternative choices to the non-food-grade emulsifier conventionally used Pluronic® F127. We described a food emulsifiers' toolbox, investigating their ability to emulsify mesophases (stabilization capacity, particle size, zeta potential) and their impact on internal nanostructures (from swelling to drastic modifications). Among the selected surfactants, sucrose stearate (S1670) was found to be the best candidate for replacing in a long term F127 as an efficient stabilizer of lipid particles. The emulsification performed by mixing F127 with S1670 or sodium caseinate (NaCas), and S1670/NaCas helped to discriminate their respective role in the particles and so their efficiency for the stabilization. In case of S1670 as co-emulsifier no strong structural modification was observed, while using F127 (25wt% NaCas) an unexpected hexagonal mesophase was highlighted in self-assemblies. The evolution of zeta potentials by varying the mesophase and the emulsifier also informed about the distribution of co-surfactants in the particles. We thus reported submicronic nanostructured systems (from 100 to 350nm) that were fully food-grade and possibly contained limonene, with a surface charge from -70 to -5mV.

  18. Mesophase pitch-based carbon fiber for improved inflammability of CFRP

    SciTech Connect

    Nakagoshi, Akira; Tomonoh, Shigeki; Sakamoto, Yosihiro

    1995-10-01

    Carbon Fiber Reinforced Plastics (CFRP) are extensively used because of their favorable physical properties such as high strength-to-weight ratio and small thermal expansion. However, flammability of CFRP has limited their application especially in the transportation and industrial field. Exposed to flame, CFRP laminates made of PAN-based carbon fibers burst into flame in short time, while CFRP laminates made from mesophase pitch-based carbon fibers don`t burst into flame. This paper describes the experimental results of local heating test by gas burner. When the flame temperature was 1,000 C, a CFRP laminate made from PAN-based carbon fiber burned within 40 sec. Under the same condition, a CFRP laminate made from mesophase pitch-based carbon fiber didn`t burn in 10 min. The matrix resin of both laminates was 250 F curable epoxy resin. This behavior mainly depends upon the thermal conductivity of the carbon fibers. The mesophase pitch-based carbon fibers have high thermal conductivity, so they can diffuse thermal energy and lower laminate surface temperature. On the other hand, PAN-based carbon fibers have low thermal conductivity, so they can`t diffuse thermal energy enough, and the laminates made from them burn easily. Mechanical properties of CFRP during local heating test in comparison with Aluminum plate are also discussed.

  19. A macroscopic H+ and Cl− ions pump via reconstitution of EcClC membrane proteins in lipidic cubic mesophases

    PubMed Central

    Speziale, Chiara; Salvati Manni, Livia; Manatschal, Cristina; Landau, Ehud M.; Mezzenga, Raffaele

    2016-01-01

    Functional reconstitution of membrane proteins within lipid bilayers is crucial for understanding their biological function in living cells. While this strategy has been extensively used with liposomes, reconstitution of membrane proteins in lipidic cubic mesophases presents significant challenges related to the structural complexity of the lipid bilayer, organized on saddle-like minimal surfaces. Although reconstitution of membrane proteins in lipidic cubic mesophases plays a prominent role in membrane protein crystallization, nanotechnology, controlled drug delivery, and pathology of diseased cells, little is known about the molecular mechanism of protein reconstitution and about how transport properties of the doped mesophase mirror the original molecular gating features of the reconstituted membrane proteins. In this work we design a general strategy to demonstrate correct functional reconstitution of active and selective membrane protein transporters in lipidic mesophases, exemplified by the bacterial ClC exchanger from Escherichia coli (EcClC) as a model ion transporter. We show that its correct reconstitution in the lipidic matrix can be used to generate macroscopic proton and chloride pumps capable of selectively transporting charges over the length scale of centimeters. By further exploiting the coupled chloride/proton exchange of this membrane protein and by combining parallel or antiparallel chloride and proton gradients, we show that the doped mesophase can operate as a charge separation device relying only on the reconstituted EcClC protein and an external bias potential. These results may thus also pave the way to possible applications in supercapacitors, ion batteries, and molecular pumps. PMID:27313210

  20. Structural and optical investigations of TGBA and TGBC mesophases exhibiting cylindrical and cone-like domain textures

    NASA Astrophysics Data System (ADS)

    Ribeiro, A. C.; Oswald, L.; Nicoud, J. F.; Guillon, D.; Galerne, Y.

    1998-02-01

    The characterization by optical microscopy, X-ray diffraction and differential scanning calorimetry of two new liquid crystalline compounds is presented. The compounds under consideration incorporate in their molecules two chiral centres (one asymmetric carbon and one asymmetric sulphur of a sulphinate group). While the carbon chirality is fixed in the R configuration the sulphur chirality may be either in the S or in the R configuration. A TGBA mesophase in a large temperature domain is evidenced for one of the two diastereomers, while both TGBA and TGBC mesophases are observed in a similar temperature domain for the other one. For both diastereomers and in both mesophases it is possible to observe the coexistence of two different types of optical textures, namely planar cholesteric textures and developable domains. The latter are coiled in a different way than proposed in an earlier publication. More precisely, they form cylindrical or cone-like domains with double-twist properties as observed in the blue phases. The pitch of the helix in the TGB mesophases is evaluated by means of optical reflection observations in samples exhibiting the planar cholesteric textures. For both diastereomers it is also possible to evaluate structural parameters related to the organization within the TGBA mesophases. Finally, the induced phase transition TGBC-SC* is studied by the application of an AC electric field.

  1. Sodium diclofenac and cell-penetrating peptides embedded in H(II) mesophases: physical characterization and delivery.

    PubMed

    Cohen-Avrahami, Marganit; Libster, Dima; Aserin, Abraham; Garti, Nissim

    2011-09-01

    Glycerol monooleate (GMO)-based mesophases offer extensive prospects for incorporation of various bioactive molecules. This work deals with the solubilization of selected cell-penetrating peptides (CPPs) together with sodium diclofenac (Na-DFC) within the H(II) mesophase for transdermal applications. The effect of CPPs such as RALA (an amphipatic CPP), penetratin (PEN), and oligoarginine (NONA) on Na-DFC skin permeation kinetics to provide controlled release and tune the drug transdermal diffusion was studied. The location of the drug and the CPPs within the mesophase was probed by DSC and FTIR. Na-DFC was found to be located at the interfacial region between the surfactant chains, leading to denser H(II) mesophase. The hydrophilic NONA was intercalated into the aqueous cylinders and caused their swelling. It induced a significant decrease in the hydrogen binding between the GMO carbonyls and their surrounding. The amphiphilic PEN was entrapped within two different regions, depending on its concentration. PEN and NONA improved Na-DFC permeation by 100%, whereas RALA enhanced permeation by 50%. When estimating Na-DFC migration rate out of the mesophase toward surrounding aqueous media, it appeared to be slower with the CPPs. The peptides were not involved at this diffusion-controlled step. It seems that their effect on skin permeation is based on their specific interaction with the skin.

  2. Structural characterization and molecular order of rodlike mesogens with three- and four-ring core by XRD and 13C NMR spectroscopy.

    PubMed

    Reddy, M Kesava; Reddy, K Subramanyam; Yoga, K; Prakash, M; Narasimhaswamy, T; Mandal, A B; Lobo, Nitin P; Ramanathan, K V; Rao, D S Shankar; Prasad, S Krishna

    2013-05-09

    Structural characterizations using XRD and (13)C NMR spectroscopy of two rodlike mesogens consisting of (i) three phenyl ring core with a polar cyano terminal and (ii) four phenyl ring core with flexible dodecyl terminal chain are presented. The three-ring-core mesogen with cyano terminal exhibits enantiotropic smectic A phase while the four-ring mesogen reveals polymesomorphism and shows enantiotropic nematic, smectic C, and tilted hexatic phases. The molecular organization in the three-ring mesogen is found to be partial bilayer smectic Ad type, and the interdigitation of the molecules in the neighboring layers is attributed to the presence of the polar terminal group. For the four-ring mesogen, the XRD results confirm the existence of the smectic C and the tilted hexatic mesophases. A thermal variation of the layer spacing across the smectic C phase followed by a discrete jump at the transition to the tilted hexatic phase is also observed. The tilt angles have been estimated to be about 45° in the smectic C phase and about 40° in tilted hexatic phase. (13)C NMR results indicate that in the mesophase the molecules are aligned parallel to the magnetic field. From the (13)C-(1)H dipolar couplings determined from the 2D experiments, the overall order parameter for the three-ring mesogen in its smectic A phase has been estimated to be 0.72 while values ranging from 0.88 to 0.44 have been obtained for the four-ring mesogen as it passes from the tilted hexatic to the nematic phase. The orientations of the different rings of the core unit with respect to each other and also with respect to the long axis of the molecule have also been obtained.

  3. Evaluating the link between self-assembled mesophase structure and drug release.

    PubMed

    Phan, Stephanie; Fong, Wye-Khay; Kirby, Nigel; Hanley, Tracey; Boyd, Ben J

    2011-12-12

    Lipid-based liquid crystalline materials are of increasing interest for use as drug delivery systems. The intricate nanostructure of the reversed bicontinuous cubic (V(2)) and inverse hexagonal (H(2)) liquid crystal matrices have been shown to provide diffusion controlled release of actives of varying size and polarity. In this study, we extend the understanding of release to other self-assembled phases, the micellar cubic phase (I(2)) and inverse micelles (L(2)). The systems are comparable as they were all prepared from the one lipid, glyceryl monooleate (GMO), which sequentially forms all four phases with increasing hexadecane (HD) content in excess water. Phase identity was confirmed by small angle X-ray scattering (SAXS). SAXS data indicated that four mesophases were formed with increasing HD content at 25°C: V(2) phase (Pn3m space group) formed at 0-4% (w/w) HD, H(2) phase formed at 4-25% (w/w) HD, I(2) phase (Fd3m space group) formed at 25-40% (w/w) HD and finally L(2) phase formed at >40% (w/w) HD. Analogous compositions using phytantriol rather than GMO as the core lipid did not produce the I(2) phase, with only V(2) to H(2) to L(2) transitions being apparent with increasing HD concentration. In order to relate the liquid crystal phase structure to drug release rate, in vitro release tests were conducted by incorporating radio-labelled glucose as a model hydrophilic drug into the four GMO-based mesophases. It was found that the drug release followed first-order diffusion kinetics and was fastest from V(2) followed by L(2), H(2), and I(2). Drug release was shown to be significantly faster from bicontinuous cubic phase than the other mesophases, indicating that the state of the water compartments, whether open or closed, has a great influence on the rate of drug release. It is envisioned that liquid crystalline mesophases with slower release characteristics will more likely have potential applications as sustained release drug delivery systems, and hence

  4. Three dielectric constants and orientation order parameters in nematic mesophases

    NASA Astrophysics Data System (ADS)

    Yoon, Hyung Guen; Jeong, Seung Yeon; Kumar, Satyendra; Park, Min Sang; Park, Jung Ok; Srinivasarao, M.; Shin, Sung Tae

    2011-03-01

    Temperature dependence of the three components ɛ1 , ɛ2 , and ɛ3 of dielectric constant and orientation order parameters in the nematic phase of mesogens with rod, banana, and zero-order dendritic shape were measured using the in-plane and vertical switching geometries, and micro-Raman technique. Results on the well-known uniaxial (Nu) nematogens, E7 and 5CB, revealed two components ɛ1 = ~ɛ| | and ɛ2 = ~ɛ3 = ~ɛ⊥ , as expected. The three dielectric constants were different for two azo substituted (A131 and A103) and an oxadiazole based (ODBP-Ph-C12) bent core mesogens, and a Ge core tetrapode. In some cases, two of the components became the same indicating a loss of biaxiality at temperatures coinciding with the previously reported Nu to biaxial nematic transition. This interpretation is substantiated by micro-Raman measurements of the uniaxial and biaxial nematic order parameters. Supported by the US Department of Energy, Basic Energy Sciences grant ER46572 and by Samsung Electronics Corporation.

  5. Geometry induced sequence of nanoscale Frank–Kasper and quasicrystal mesophases in giant surfactants

    SciTech Connect

    Yue, Kan; Huang, Mingjun; Marson, Ryan L.; He, Jinlin; Huang, Jiahao; Zhou, Zhe; Wang, Jing; Liu, Chang; Yan, Xuesheng; Wu, Kan; Guo, Zaihong; Liu, Hao; Zhang, Wei; Ni, Peihong; Wesdemiotis, Chrys; Zhang, Wen-Bin; Glotzer, Sharon C.; Cheng, Stephen Z. D.

    2016-11-28

    Frank–Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails. We show that the occurrence of these mesophases results from nanophase separation between the heads and tails and thus is critically dependent on molecular geometry. Variations in molecular geometry achieved by changing the number of tails from one to four not only shift compositional phase boundaries but also stabilize F-K and quasicrystal phases in regions where simple phases of spheroidal micelles are typically observed. These complex self-assembled nanostructures have been identified by combining X-ray scattering techniques and real-space electron microscopy images. Brownian dynamics simulations based on a simplified molecular model confirm the architecture-induced sequence of phases. Our results demonstrate the critical role of molecular architecture in dictating the formation of supramolecular crystals with “soft” spheroidal motifs and provide guidelines to the design of unconventional self-assembled nanostructures.

  6. Influence of mesophase activation conditions on the specific capacitance of the resulting carbons

    NASA Astrophysics Data System (ADS)

    Mora, E.; Ruiz, V.; Santamaría, R.; Blanco, C.; Granda, M.; Menéndez, R.; Juarez-Galán, J. M.; Rodríguez-Reinoso, F.

    Mesophase pitch AR24 was directly activated with KOH using different proportions of the activating agent and activation temperatures, to study the effect on the textural characteristics of the resultant activated carbons and how these characteristics influence their behaviour as electrodes in supercapacitors. The textural properties of the activated carbons were studied by gas adsorption and immersion calorimetry. The results indicate that all the carbons produced were mainly microporous, with pore size around 1 nm. The behaviour of these carbons as electrodes in supercapacitors was studied from galvanostatic charge-discharge cycles. The specific capacitance values obtained were very high, reaching 400 and 200 F g -1 at low and high current densities respectively, for the sample activated with (5:1) KOH to mesophase ratio. Nevertheless, the reasons for this high capacitance values cannot be explained only on the basis of the textural characteristics of the activated carbons, as the results indicated that other factors might be also playing a significant role in their electrochemical behaviour.

  7. Modulation of physical properties of reverse hexagonal mesophases: a dielectric spectroscopy study.

    PubMed

    Mishraki, Tehila; Ben Ishai, Paul; Babukh, Dmitry; Aserin, Abraham; Feldman, Yuri; Garti, Nissim

    2013-04-15

    The structural, dynamic, and kinetic aspects of the HII systems based on glycerol monooleate (GMO), phosphatidylcholine (PC), triacylglycerol (TAG), and water were investigated by dielectric spectroscopy in a frequency range of 10(-2)-10(6) Hz, and a temperature range of 290-320 K. Three distinct processes as well as a temperature-activated dc conductivity were detected and examined. These were assigned to the reorientation of the GMO polar heads, the tangential movement of counterions at the interface, the transport of TAGs through the lipids tails, and the ion mobility within the water cylinders. Upon addition of PC, the critical temperature (T0) of the dehydration of the GMO headgroups increased. The optimal concentration found for structural stabilization of the HII mesophase was 10 wt% PC, since it imparted the strongest bonding at the interfacial layer and increased the association between the lipid tails. Within the HII cluster, TAG percolated and shifted between the hexagonal rods themselves. The present study demonstrated the benefit of controlling the critical temperature of the HII mesophase partial dehydration and softening, as well as the percolation of TAGs. These factors influence the diffusion mode of embedded drugs in the physiological temperature range.

  8. On the use of mesophase pitch for the preparation of hierarchical porous carbon monoliths by nanocasting

    NASA Astrophysics Data System (ADS)

    Adelhelm, Philipp; Cabrera, Karin; Smarsly, Bernd M.

    2012-02-01

    A detailed study is given on the synthesis of a hierarchical porous carbon, possessing both meso- and macropores, using a mesophase pitch (MP) as the carbon precursor. This carbon material is prepared by the nanocasting approach involving the replication of a porous silica monolith (hard templating). While this carbon material has already been tested in energy storage applications, various detailed aspects of its formation and structure are addressed in this study. Scanning electron microscopy (SEM), Hg porosimetry and N2 physisorption are used to characterize the morphology and porosity of the carbon replica. A novel approach for the detailed analysis of wide-angle x-ray scattering (WAXS) from non-graphitic carbons is applied to quantitatively compare the graphene microstructures of carbons prepared using MP and furfuryl alcohol (FA). This WAXS analysis underlines the importance of the carbon precursor in the synthesis of templated porous carbon materials via the nanocasting route. Our study demonstrates that a mesophase pitch is a superior precursor whenever a high-purity, low-micropore-content and well-developed graphene structure is desired.

  9. Structural rearrangements and interaction within H(II) mesophase induced by cosolubilization of vitamin E and ascorbic acid.

    PubMed

    Bitan-Cherbakovsky, Liron; Yuli-Amar, Idit; Aserin, Abraham; Garti, Nissim

    2009-11-17

    We investigated the effect of ascorbic acid (AA) cosolubilized with vitamin E (VE) on reverse hexagonal (H(II)) mesophase. The H(II) phase comprises monoolein (GMO)/d-alpha-tocopherol (VE) in a ratio of 90/10 by weight and 12.5 wt % water. The macrostructural characteristics of this system were determined by polarized light microscopy and small-angle X-ray scattering measurements. We used differential scanning calorimetry and attenuated total reflectance Fourier transform infrared to characterize the microstructure, the vibration of the functional groups, and the location of the AA guest molecule. AA was incorporated to the system in two steps: 1-4 wt % AA and 5-6 wt % AA. We compared this system to one containing tricaprylin as the oil phase, as previously reported. These measurements revealed that AA is localized first in the water rich-core and in the interface, and acts as a chaotropic molecule that decreases the water melting point. When a larger quantity of AA (5-6 wt %) is added, the system is saturated, and the AA is located in the inner cylinder and manifested by more moderate distortion. The addition of AA also causes alteration in the behavior of the GMO hydrocarbon chains and makes them more flexible. Further addition of AA caused the GMO hydrocarbon chain to be more solvated by the VE hydrocarbon chain and enabled additional migration of VE; hence a decrease in the hydrophobic melting temperature occurred (similar to tricaprylin). Increasing the amount of AA weakened the bonding between the GMO and water and created new bonds between AA and GMO and AA with water.

  10. The effect of cation structure on the mesophase architecture of self-assembled and polymerized imidazolium-based ionic liquids.

    SciTech Connect

    Batra, D.; Seifert, S.; Firestone, M. A.; Materials Science Division

    2007-01-01

    The binary phase behavior of a series of imidazolium-based ionic liquids (ILs) has been investigated. In particular, the effect of two structural modifications of the imidazolium cation, alkyl chain length, and the introduction of a polymerizable acryloyl group at the alkyl chain terminus, has been studied using small angle X-ray scattering. Upon increasing water content, the non-polymerizable IL, 1-decyl-3-methylimidazolium chloride, adopts mesophase structures of predominately two-dimensional (2D) hexagonal symmetry, including structures intermediate in character between lamellae and 2D hexagonal micelles. Introduction of a photopolymerizable acryloyl functional group to form 1-(10-(acryloyloxy)decyl)-3-methylimidazolium chloride produces a rod-coil IL cation that yields self-assembled mesophases in which the formation of tetragonal morphologies is favored. Covalent linking of the IL cations by UV-induced polymerization converts the lyotropic mesophase into three-dimensional biocontinuous chemical gels. Reducing the alkyl chain length, as in the polymerizable IL cation 1-(8-(acryloyloxy)octyl)-3-methylimidazolium chloride, severely reduces the self-assembled mesophase order, and triggers the formation of only weakly ordered one-dimensional lamellar structures.

  11. Effect of reduction on graphitization behavior of mesophase pitch-derived carbon fibers

    NASA Astrophysics Data System (ADS)

    Kim, Y. A.; Muramatsu, H.; Kojima, M.; Hayashi, T.; Kim, C.; Endo, M.; Dresselhaus, M. S.

    2005-06-01

    Chemically reduced solid-state mesophase pitch carbon fibers below 1000 °C in a flow of hydrogen gas were treated up to 3000 °C in an argon atmosphere in order to evaluate the effect of hydrogen on the graphitization behavior. Major phenomena observed during the reduction process are chemical transformation from an ether to a hydroxyl group (corresponding to the rupture of the C-O-C bond) and their subsequent evolution as gases. Finally, oversupplied hydrogen might be utilized to satisfy the dangling bond. For the sample heat treated at 3000 °C, the low crystallinity indicates that hydrogen atoms covalently bonded to the end planes of graphitic layers act as an effective barrier to crystallite growth.

  12. Characteristics of mesophase pitch-based carbon fibers as anode materials for lithium secondary cells

    SciTech Connect

    Tamaki, Toshio

    1995-12-31

    Mesophase pitch-based Carbon Fibers (MPCF) have been investigated as anode materials for lithium secondary cells by examining their physical and electrochemical properties. Discharge capacity and initial charge-discharge efficiency of the materials were studied in relation to the heat treatment temperatures of MPCF. Carbon fiber which was heat treated at about 3,000 C gave the highest discharge capacity (over 300 mAh/g), good efficiency (92%) and superior current capability (600 mA/g). Carbon fiber heat treated at less than 1,000 C, also has superior discharge capacity (over 500 mAh/g) at the first cycle, however efficiency was relatively low. Some of the relationships between structure of MPCF and electrochemical properties are discussed.

  13. Charge-discharge characteristics of mesophase-pitch-based carbon fibers for lithium cells

    SciTech Connect

    Imanishi, N.; Kashiwagi, H.; Ichikawa, T.; Takeda, Y.; Yamamoto, O. ); Inagaki, M. )

    1993-02-01

    Mesophase-pitch-based carbon fibers were heat-treated at high temperatures (2,600 or 2,800 C) and examined as anodes for lithium secondary batteries. Four types of carbon fibers were used whose cross-sectional views are: a radial texture with wedge (type A), a radial texture with fine zigzag layers (type B), a double texture (type C), and a concentric texture (type D). Lithium could not be deintercalated after the first lithium intercalation in the type A carbon fiber. The structure of the type A fiber was destroyed during lithium intercalation. The other three types of carbon fibers showed good rechargeability on the first cycle, but demonstrated different behavior after 30 cycles. The highest lithium intercalation and deintercalation capacity was observed for the radially oriented carbon fiber (type B). The x-ray results showed a reversible change in the lattice along the c-axis during the intercalation and deintercalation cycle.

  14. Modelling of single bubble growth in carbon nanofibre filled mesophase pitch during carbonization

    NASA Astrophysics Data System (ADS)

    Calebrese, Christopher; Schadler, Linda S.; Lewis, Daniel J.

    2010-06-01

    A single bubble growth model is presented for bubble growth in mesophase pitch during carbonization. This model is distinguished from typical polymer foaming models in its design to be used over a wider temperature range, its accounting for mass transfer from the liquid to the bubble, and the incorporation of reaction sites in the melt which produce volatile gases. The effect of nanofibre loading on growth is investigated in terms of viscosity, density and volatile concentration. It is found that the viscosity change is the controlling factor in altering the bubble growth rate in this system. Comparison with experimental data shows that a single bubble growth model is a reasonable assumption for carbon nanofibre loading of 1 wt% or below.

  15. The curvature elastic-energy function of the lipid-water cubic mesophase

    NASA Astrophysics Data System (ADS)

    Chung, Hesson; Caffrey, Martin

    1994-03-01

    CELL and lipid membranes are able to bend, as manifested during membrane fusion and the formation of non-lamellar lyotropic mesopbases in water. But there is an energy cost to bending of lipid layers, called the curvature elastic energy. Although the functional form of this energy is known1, a complete quantitative knowledge of the curvature elastic energy, which is central to predicting the relative stability of the large number of phases that lipid membranes can adopt, has been lacking. Here we use X-ray synchrotron diffraction measurements of the variation of lattice parameter with pressure and temperature for the periodic Ia3d (Q230) cubic phase of hydrated monoolein to calculate the complete curvature elastic-energy function for the lipid cubic mesophase. This allows us to predict the stabilities of different cubic and lamellar phases for this system as a function of composition.

  16. Single-walled carbon nanotube buckypaper and mesophase pitch carbon/carbon composites

    NASA Astrophysics Data System (ADS)

    Park, Jin Gyu; Yun, Nam Gyun; Park, Young Bin; Liang, Richard; Lumata, Lloyd; Brooks, James; Zhang, Chuck; Wang, Ben; High-Performance Materials Institute, Fsu Collaboration; National High Magnetic Field Laboratory, Fsu Collaboration

    2011-03-01

    Carbon/carbon composites consisting of single-walled carbon nanotube (SWCNT) buckypaper (BP) and mesophase pitch resin have been produced through impregnation of BP with pitch using toluene as a solvent. Drying, stabilization and carbonization processes were performed sequentially, and repeated to increase the pitch content. Voids in the carbon/carbon composite samples decreased with increasing impregnation process cycles. Electrical conductivity and density of the composites increased with carbonization by two to three times that of pristine BP. These results indicate that discontinuity and intertube contact barriers of SWCNTs in the BP are partially overcome by the carbonization process of pitch. The temperature dependence of the Raman shift shows that mechanical strain is increased since carbonized pitch matrix surrounds the nanotubes. High-Performance Materials Institute, NSF DMR-0602859, NSF DMR-0654118.

  17. Antipolar and Anticlinic Mesophase Order in Chromatin Induced by Nucleosome Polarity and Chirality Correlations

    NASA Astrophysics Data System (ADS)

    Garcés, R.; Podgornik, R.; Lorman, V.

    2015-06-01

    Contrary to the usual "rigid supermolecular assembly" paradigm of chromatin structure, we propose to analyze its eventual ordered state in terms of symmetry properties of individual nucleosomes that give rise to mesophase order parameters, like in many other soft-matter systems. Basing our approach on the Landau-de Gennes phenomenology, we describe the mesoscale order in chromatin by antipolar and anticlinic correlations of chiral individual nucleosomes. This approach leads to a unifying physical picture of a whole series of soft locally ordered states with different apparent structures, including the recently observed heteromorphic chromatin, stemming from the antipolar arrangement of nucleosomes complemented by their chiral twisting. Properties of these states under an external force field can reconcile apparently contradictory results of single-molecule experiments.

  18. Structural analysis of the B-doped mesophase pitch-based graphite fibers by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Endo, M.; Kim, C.; Karaki, T.; Tamaki, T.; Nishimura, Y.; Matthews, M. J.; Brown, S. D. M.; Dresselhaus, M. S.

    1998-10-01

    Milled B-doped mesophase pitch-based carbon fibers (mMPCF's) prepared from a melt-blown petroleum mesophase pitch precursor material have been developed for enhanced Li uptake capacity in Li ion batteries. Raman spectroscopy has been used to investigate the structure of graphitized and B-doped mMPCF's using 632.8-nm HeNe laser excitation. The B-doped mMPCF's show a strong Raman peak near 1330 cm-1, a well-defined peak at 1620 cm-1, and the disappearance of the second-order 2660 cm-1 band. Furthermore, it is shown that the E2g2 graphite Raman band at 1580 cm-1 is shifted to 1590 cm-1 due to B doping. The appearance of a new weak Raman band in the B-doped mMPCF's near 1320 cm-1 is closely related to the B-C stretching mode in the graphite lattice. These results are associated with the breakdown of the k=0 selection rules by a local distortion of the graphite lattice due to substitutional boron doping. On the basis of the integrated intensity ratio R of the disorder-induced line near 1330 cm-1 to the Raman line near 1590 cm-1 after 2.66 at. % boron doping, it is suggested that the substitutional boron in the mMPCF's is homogeneously distributed within the graphene layer in the fiber form. The crystallite domain size La parallel and perpendicular to the fiber axis on the surface of the fiber is estimated to be about 60 Å, which could correspond to the distance between boron atoms substituted for C atoms in a graphene layer of the fibers.

  19. Dielectric, calorimetric and mesophase properties of 1''-(2',4-difluorobiphenyl-4'-yloxy)-9''-(4-cyanobiphenyl-4'-yloxy) nonane: an odd liquid crystal dimer with a monotropic mesophase having the characteristics of a twist-bend nematic phase.

    PubMed

    Sebastián, N; López, D O; Robles-Hernández, B; de la Fuente, M R; Salud, J; Pérez-Jubindo, M A; Dunmur, D A; Luckhurst, G R; Jackson, D J B

    2014-10-21

    This paper reports a novel liquid crystal phase having the characteristics of a twist-bend nematic phase formed by a non-symmetric ether-linked liquid crystal dimer. The dimer 1''-(2',4-difluorobiphenyl-4'-yloxy)-9''-(4-cyanobiphenyl-4'-yloxy) nonane (FFO9OCB) exhibits two liquid-crystalline phases on cooling at a sufficiently high rate from the isotropic phase. The high temperature mesophase has been reported in the literature as nematic and confirmed in this study. The other mesophase is metastable and can be supercooled giving rise to a glassy state. Its identification and characterization are based on optical textures, broadband dielectric spectroscopy, calorimetry, measurements of both splay and bend elastic constants in the nematic phase and miscibility studies. It is concluded that the low temperature mesophase exhibits the characteristics of a twist-bend nematic phase. Dielectric measurements enable us to obtain the static permittivity and information about the molecular dynamics in the isotropic phase, in the nematic mesophase and across the isotropic-to-nematic phase transition. Two orientations, parallel and perpendicular to the director, have been investigated. In the high temperature nematic mesophase, the dielectric anisotropy is found to be positive. Measurements of the parallel component of the dielectric permittivity are well-explained by the molecular theory of dielectric relaxation in nematic dimers (M. Stocchero, A. Ferrarini, G. J. Moro, D. A. Dunmur and G. R. Luckhurst, J. Chem. Phys., 2004, 121, 8079). The dimer is modelled as a mixture of cis and trans conformers and the model allows an estimate of their relative populations at each temperature. The nematic-to-isotropic phase transition has been exhaustively studied from the accurate evolution of the heat capacity and the static dielectric permittivity data. It has been concluded that the transition is first order in nature, but close to tricritical. The nature of the nematic-to-the novel

  20. Experimental study and modeling of swelling and bubble growth in carbon nanofiber filled mesophase pitch during carbonization

    NASA Astrophysics Data System (ADS)

    Calebrese, Christopher

    Graphite and all carbon bipolar plates show corrosion resistance in fuel cells and provide good electrical conductivity. These materials typically need to be individually machined, a time consuming and costly process. Mesophase pitch is used to manufacture carbon fibers and carbon-carbon composites. This material provides a good starting point for the production of a moldable, all carbon bipolar plate. However, processing of mesophase pitch to produce all carbon materials requires a time intensive oxidation step to prevent swelling during carbonization. In this work, carbon nanofibers were used to reduce swelling in mesophase pitch. It was found that the increase in viscosity with the addition of carbon nanofibers was responsible for the reduction in swelling. The influence of the filler became apparent above the percolation threshold. At loadings below the percolation threshold, the swelling of the mesophase pitch was not reduced after carbonization. The swelling of the mesophase pitch at a given carbon nanofiber loading was also dependent on the length of the carbon nanofibers. Longer carbon nanofibers led to greater increases in the viscosity of the melt and thus led to greater reduction in swelling. The final carbon product was evaluated for use as a low temperature fuel cell bipolar plate material. Constraining the mesophase pitch during carbonization led to a final product with strength and electrical conductivity comparable to current composite bipolar plate materials. The addition of micron size chopped glass fibers with a softening point near 850°C and carbon nanofibers led to a final product with air permeability less than that of graphite. A spherically symmetric, single bubble growth model was also developed. The model included temperature dependence, liquid to bubble mass transfer and reactions in the system. Results from simulations showed that that the increase in viscosity due to the addition of carbon nanofibers slows the growth of bubbles, but

  1. Characteristics of coke carbon modified with mesophase-pitch as a negative electrode for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Sato, Yuichi; Kikuchi, Yasuo; Nakano, Takeshi; Okuno, Gaku; Kobayakawa, Koichi; Kawai, Takanobu; Yokoyama, Akira

    To increase the charge-discharge capacity of carbon electrodes for lithium ion secondary batteries, coke carbon, a relatively cheap material, was modified with mesophase-pitch carbon by a heat treatment. While coke carbon powder, mesophase-pitch, and a mixture thereof (4:1 by weight) supplied between 0 and 1.5 V vs. Li/Li + an initial discharge capacity of about 295 mAh/g, 310 mAh/g, and 310 mAh/g, respectively, the modified coke deintercalated 400 mA h/g of lithium with a high degree of reversibility. The difference in capacity between the modified carbon and mixture are discussed based on the shape of their current-potential curves and their galvanostatic charge-discharge curves.

  2. Not Only Columns: High Hole Mobility in a Discotic Nematic Mesophase Formed by Metal-Containing Porphyrin-Core Dendrimers.

    PubMed

    Concellón, Alberto; Marcos, Mercedes; Romero, Pilar; Serrano, José Luis; Termine, Roberto; Golemme, Attilio

    2017-01-24

    We report a new family of multifunctional liquid-crystalline porphyrin-core dendrimers that have coumarin functional groups around the porphyrin core. Porphyrin metalation strongly affects the photophysical properties, and therefore Zn(II) and Cu(II) derivatives have also been prepared. All the synthesized dendrimers form a nematic discotic mesophase. Their high tendency for homeotropic alignment makes these dendrimers excellent candidates for device applications, owing to their easy processability, spontaneous alignment between electrodes, and self-healing of defects because of their dynamic nature. The charge mobility values of these materials are the highest ever reported for a nematic discotic phase. Moreover, these values are similar to the highest values reported for ordered columnar mesophases, and this shows that a supramolecular organization in columns is not necessary to achieve high charge mobility.

  3. Deconvoluting the Effect of the Hydrophobic and Hydrophilic Domains of an Amphiphilic Integral Membrane Protein in Lipid Bicontinuous Cubic Mesophases.

    PubMed

    van 't Hag, Leonie; Shen, Hsin-Hui; Lu, Jingxiong; Hawley, Adrian M; Gras, Sally L; Drummond, Calum J; Conn, Charlotte E

    2015-11-10

    Lipidic bicontinuous cubic mesophases with encapsulated amphiphilic proteins are widely used in a range of biological and biomedical applications, including in meso crystallization, as drug delivery vehicles for therapeutic proteins, and as biosensors and biofuel cells. However, the effect of amphiphilic protein encapsulation on the cubic phase nanostructure is not well-understood. In this study, we illustrate the effect of incorporating the bacterial amphiphilic membrane protein Ag43, and its individual hydrophobic β(43) and hydrophilic α(43) domains, in bicontinuous cubic mesophases. For the monoolein, monoalmitolein, and phytantriol cubic phases with and without 8% w/w cholesterol, the effect of the full length amphiphilic protein Ag43 on the cubic phase nanostructure was more significant than the sum of the individual hydrophobic β(43) and hydrophilic α(43) domains. Several factors were found to potentially influence the impact of the hydrophobic β(43) domain on the cubic phase internal nanostructure. These include the size of the hydrophobic β(43) domain relative to the thickness of the lipid bilayer, as well as its charge and diameter. The size of the hydrophilic α(43) domain relative to the water channel radius of the cubic mesophase was also found to be important. The secondary structure of the Ag43 proteins was affected by the hydrophobic thickness and physicochemical properties of the lipid bilayer and the water channel diameter of the cubic phase. Such structural changes may be small but could potentially affect membrane protein function.

  4. Membrane Protein Crystallization in Lipidic Mesophases. Hosting lipid affects on the crystallization and structure of a transmembrane peptide.

    PubMed

    Höfer, Nicole; Aragão, David; Lyons, Joseph A; Caffrey, Martin

    2011-04-06

    Gramicidin is an apolar pentadecapeptide antibiotic consisting of alternating D-and L-amino acids. It functions, in part, by creating pores in membranes of susceptible cells rendering them leaky to monovalent cations. The peptide should be able to traverse the host membrane either as a double stranded, intertwined double helix (DSDH) or as a head-to-head single stranded helix (HHSH). Current structure models are based on macromolecular X-ray crystallography (MX) and nuclear magnetic resonance (NMR). However, the HHSH form has only been observed by NMR. The shape and size of the different gramicidin conformations differ. We speculated therefore that reconstituting it into a lipidic mesophase with bilayers of different microstructures would preferentially stabilize one form over the other. By using such mesophases for in meso crystallogenesis the expectation was that at least one would generate crystals of gramicidin in the HHSH form for structure determination by MX. This was tested using commercial and in-house synthesised lipids that support in meso crystallogenesis. Lipid acyl chain lengths were varied from 14 to 18 carbons to provide mesophases with a range of bilayer thicknesses. Unexpectedly, all lipids produced high quality, structure-grade crystals with gramicidin only in the DSDH conformation.

  5. Membrane Protein Crystallization in Lipidic Mesophases. Hosting lipid affects on the crystallization and structure of a transmembrane peptide

    PubMed Central

    Höfer, Nicole; Aragão, David; Lyons, Joseph A.; Caffrey, Martin

    2012-01-01

    Gramicidin is an apolar pentadecapeptide antibiotic consisting of alternating D-and L-amino acids. It functions, in part, by creating pores in membranes of susceptible cells rendering them leaky to monovalent cations. The peptide should be able to traverse the host membrane either as a double stranded, intertwined double helix (DSDH) or as a head-to-head single stranded helix (HHSH). Current structure models are based on macromolecular X-ray crystallography (MX) and nuclear magnetic resonance (NMR). However, the HHSH form has only been observed by NMR. The shape and size of the different gramicidin conformations differ. We speculated therefore that reconstituting it into a lipidic mesophase with bilayers of different microstructures would preferentially stabilize one form over the other. By using such mesophases for in meso crystallogenesis the expectation was that at least one would generate crystals of gramicidin in the HHSH form for structure determination by MX. This was tested using commercial and in-house synthesised lipids that support in meso crystallogenesis. Lipid acyl chain lengths were varied from 14 to 18 carbons to provide mesophases with a range of bilayer thicknesses. Unexpectedly, all lipids produced high quality, structure-grade crystals with gramicidin only in the DSDH conformation. PMID:22933857

  6. Membrane Protein Crystallization in Lipidic Mesophases. Hosting Lipid Effects on the Crystallization and Structure of a Transmembrane Peptide

    SciTech Connect

    Hfer, Nicole; Aragao, David; Lyons, Joseph A.; Caffrey, Martin

    2011-09-28

    Gramicidin is an apolar pentadecapeptide antibiotic consisting of alternating d- and l-amino acids. It functions, in part, by creating pores in membranes of susceptible cells rendering them leaky to monovalent cations. The peptide should be able to traverse the host membrane either as a double-stranded, intertwined double helix (DSDH) or as a head-to-head single-stranded helix (HHSH). Current structure models are based on macromolecular X-ray crystallography (MX) and nuclear magnetic resonance (NMR). However, the HHSH form has only been observed by NMR. The shape and size of the different gramicidin conformations differ. We speculated therefore that reconstituting it into a lipidic mesophase with bilayers of different microstructures would preferentially stabilize one form over the other. By using such mesophases for in meso crystallogenesis, the expectation was that at least one would generate crystals of gramicidin in the HHSH form for structure determination by MX. This was tested using commercial and in-house synthesized lipids that support in meso crystallogenesis. Lipid acyl chain lengths were varied from 14 to 18 carbons to provide mesophases with a range of bilayer thicknesses. Unexpectedly, all lipids produced high-quality, structure-grade crystals with gramicidin only in the DSDH conformation.

  7. Harvesting and cryo-cooling crystals of membrane proteins grown in lipidic mesophases for structure determination by macromolecular crystallography.

    PubMed

    Li, Dianfan; Boland, Coilín; Aragao, David; Walsh, Kilian; Caffrey, Martin

    2012-09-02

    An important route to understanding how proteins function at a mechanistic level is to have the structure of the target protein available, ideally at atomic resolution. Presently, there is only one way to capture such information as applied to integral membrane proteins (Figure 1), and the complexes they form, and that method is macromolecular X-ray crystallography (MX). To do MX diffraction quality crystals are needed which, in the case of membrane proteins, do not form readily. A method for crystallizing membrane proteins that involves the use of lipidic mesophases, specifically the cubic and sponge phases(1-5), has gained considerable attention of late due to the successes it has had in the G protein-coupled receptor field(6-21) (www.mpdb.tcd.ie). However, the method, henceforth referred to as the in meso or lipidic cubic phase method, comes with its own technical challenges. These arise, in part, due to the generally viscous and sticky nature of the lipidic mesophase in which the crystals, which are often micro-crystals, grow. Manipulating crystals becomes difficult as a result and particularly so during harvesting(22,23). Problems arise too at the step that precedes harvesting which requires that the glass sandwich plates in which the crystals grow (Figure 2)(24,25) are opened to expose the mesophase bolus, and the crystals therein, for harvesting, cryo-cooling and eventual X-ray diffraction data collection. The cubic and sponge mesophase variants (Figure 3) from which crystals must be harvested have profoundly different rheologies(4,26). The cubic phase is viscous and sticky akin to a thick toothpaste. By contrast, the sponge phase is more fluid with a distinct tendency to flow. Accordingly, different approaches for opening crystallization wells containing crystals growing in the cubic and the sponge phase are called for as indeed different methods are required for harvesting crystals from the two mesophase types. Protocols for doing just that have been

  8. Development of mesophase pitch derived mesoporous carbons through a commercially nanosized template.

    PubMed

    Qiao, W M; Song, Y; Hong, S H; Lim, S Y; Yoon, S-H; Korai, Y; Mochida, I

    2006-04-11

    Mesoporous carbons (MCs) with a high surface area (up to 900 m2/g), large pore volume (up to 2.1 cm3/g), high mesopore ratio (94%), and high yield (70%) were successfully prepared from an AR mesophase pitch, using a commercially nanosized silica template. The removal of the template provided some larger mesopores of 25-50 nm (pore I) with a surface area of ca. 300 m2/g, while the successive carbonization opened the closed pores within the carbon body to give smaller mesopores of 2-10 nm (pore II) with a similar surface area. During the carbonization of pitch precursor, the evaporation of volatile components swells the carbon to introduce the second mesopores among the domains and even microdomain units because of their rearrangements and overlappings in the process. The addition of iron salt with the silica template resulted in a remarkable increase of the surface area (ca. 300 m2/g) by introducing mesopores of 3-5 nm. The resultant MCs maintained some graphitizable natures derived from the anisotropic precursor. Their graphitization at 2400 degrees C provided the graphitic structure with large surface areas (270-460 m2/g) and mesoporosity.

  9. High-capacity lithium-ion cells using graphitized mesophase-pitch-based carbon fiber anodes

    NASA Astrophysics Data System (ADS)

    Ohsaki, Takahisa; Kanda, Motoya; Aoki, Yoshiyasu; Shiroki, Hiroyuki; Suzuki, Shintaro

    We have developed high-capacity lithium-ion cells using graphitized mesophase-pitch-based carbon fiber (MCF) as an anode material. The graphitized MCF is a highly graphitized carbon fiber with a radial-like texture in the cross section. This structure contributes to the rapid diffusion of lithium ions inside the carbon fiber. The diffusion coefficient of lithium ions in the graphitized MCF was one order of magnitude larger than those for graphite, resulting in an excellent high-rate performance of the carbon electrode. The graphitized MCF anode showed larger capacity, a higher rate capability, and better reversibility than the graphite anode. The 863448 size (8.6 mm × 34 mm × 48 mm) prismatic cell with the graphitized MCF anode exhibited a large capacity of > 1000 mAh. At 3 A discharge, the prismatic cell had 95% of its capacity at 0.5 A discharge with a mid-discharge voltage of 3.35 V. The cell maintained > 85% of its initial capacity after 500 cycles and showed high capacity at -20 °C. It has thus been demonstrated that the prismatic cell using the graphitized MCF anode has excellent performance, and is an attractive choice for the power sources of cellular phones and other appliances.

  10. Rechargeable lithium-ion cells using graphitized mesophase-pitch-based carbon fiber anodes

    SciTech Connect

    Takami, Norio; Satoh, Asako; Hara, Michikazu; Ohsaki, Takahisa

    1995-08-01

    The electrochemistry of lithium intercalation into a graphitized mesophase-pitch-based carbon fiber with a radial-like texture used as the anode material in rechargeable lithium-ion cells was characterized. The radial-like texture in the cross section of the carbon fiber contributed to the rapid diffusion of lithium ions, resulting in the high rate capability. The anode performance of the graphitized carbon fiber was superior to that of the graphite. Experimental flat-plate C/LiCoO{sub 2} lithium-ion cells using the graphitized carbon fiber anode exhibited a high mid-discharge voltage of 3.7 V, a high rate capability, and a long cycle life of more than 400 cycles at 2 mA/cm{sup 2} mA/cm{sup 2} during charge-discharge cycling between 4.2 and 2.7 V. The long cycle life obtained for the cell was due to no significant change in resistance associated with the passivating films on the graphitized carbon fiber with extended cycles. It was also demonstrated that A size C/LiCoO{sub 2} cells using the graphitized carbon fiber anode have excellent rate performance at discharge currents between 0.25 and 3 A, a large discharge capacity of 0.95 Ah, and a high energy density of 310 Wh/dm{sup 3} and 120 Wh/kg.

  11. Molecular dynamics approach to water structure of HII mesophase of monoolein

    NASA Astrophysics Data System (ADS)

    Kolev, Vesselin; Ivanova, Anela; Madjarova, Galia; Aserin, Abraham; Garti, Nissim

    2012-02-01

    The goal of the present work is to study theoretically the structure of water inside the water cylinder of the inverse hexagonal mesophase (HII) of glyceryl monooleate (monoolein, GMO), using the method of molecular dynamics. To simplify the computational model, a fixed structure of the GMO tube is maintained. The non-standard cylindrical geometry of the system required the development and application of a novel method for obtaining the starting distribution of water molecules. A predictor-corrector schema is employed for generation of the initial density of water. Molecular dynamics calculations are performed at constant volume and temperature (NVT ensemble) with 1D periodic boundary conditions applied. During the simulations the lipid structure is kept fixed, while the dynamics of water is unrestrained. Distribution of hydrogen bonds and density as well as radial distribution of water molecules across the water cylinder show the presence of water structure deep in the cylinder (about 6 Å below the GMO heads). The obtained results may help understanding the role of water structure in the processes of insertion of external molecules inside the GMO/water system. The present work has a semi-quantitative character and it should be considered as the initial stage of more comprehensive future theoretical studies.

  12. Phospholipid-based nonlamellar mesophases for delivery systems: bridging the gap between empirical and rational design.

    PubMed

    Martiel, Isabelle; Sagalowicz, Laurent; Mezzenga, Raffaele

    2014-07-01

    Phospholipids are ubiquitous cell membrane components and relatively well-accepted ingredients due to their natural origin. Phosphatidylcholine (PC) in particular offers a promising alternative to monoglycerides for lyotropic liquid crystalline (LLC) delivery system applications in the food, cosmetics and pharmaceutical industries, provided its strong tendency to form zero-mean curvature lamellar mesophases in water can be overcome. Higher negative curvatures are usually reached through the addition of a third lipid component, forming a ternary diagram phospholipid/water/oil. The initial part of this work summarizes the potential advantages and the challenges of phospholipid-based delivery system applications. In the next part, various ternary PC/water/oil systems are discussed, with a special emphasis on the PC/water/cyclohexane and PC/water/α-tocopherol systems. We report that R-(+)-limonene has a quantitatively similar effect as cyclohexane. The last part is devoted to the theoretical interpretation of the observed phase behaviors. A fruitful parallel is drawn with PC polymer-like reverse micelles, leading to a thermodynamic description in terms of interfacial bending energy. Investigations at the molecular level are reviewed to help in bridging the empirical and theoretical approaches. Predictive rules are finally derived from this wide-ranging overview, thereby opening the way to a future rational design of PC-based LLC delivery systems.

  13. Structural modeling of carbonaceous mesophase amphotropic mixtures under uniaxial extensional flow

    NASA Astrophysics Data System (ADS)

    Golmohammadi, Mojdeh; Rey, Alejandro D.

    2010-07-01

    The extended Maier-Saupe model for binary mixtures of model carbonaceous mesophases (uniaxial discotic nematogens) under externally imposed flow, formulated in previous studies [M. Golmohammadi and A. D. Rey, Liquid Crystals 36, 75 (2009); M. Golmohammadi and A. D. Rey, Entropy 10, 183 (2008)], is used to characterize the effect of uniaxial extensional flow and concentration on phase behavior and structure of these mesogenic blends. The generic thermorheological phase diagram of the single-phase binary mixture, given in terms of temperature (T) and Deborah (De) number, shows the existence of four T-De transition lines that define regions that correspond to the following quadrupolar tensor order parameter structures: (i) oblate (⊥,∥), (ii) prolate (⊥,∥), (iii) scalene O(⊥,∥), and (iv) scalene P(⊥,∥), where the symbols (⊥,∥) indicate alignment of the tensor order ellipsoid with respect to the extension axis. It is found that with increasing T the dominant component of the mixture exhibits weak deviations from the well-known pure species response to uniaxial extensional flow (uniaxial ⊥nematic→biaxial nematic→uniaxial∥paranematic). In contrast, the slaved component shows a strong deviation from the pure species response. This deviation is dictated by the asymmetric viscoelastic coupling effects emanating from the dominant component. Changes in conformation (oblate⇄prolate) and orientation (⊥⇄∥) are effected through changes in pairs of eigenvalues of the quadrupolar tensor order parameter. The complexity of the structural sensitivity to temperature and extensional flow is a reflection of the dual lyotropic/thermotropic nature (amphotropic nature) of the mixture and their cooperation/competition. The analysis demonstrates that the simple structures (biaxial nematic and uniaxial paranematic) observed in pure discotic mesogens under uniaxial extensional flow are significantly enriched by the interaction of the lyotropic

  14. Isomorphism Within the Hexagonal Columnar Mesophase of Molecular and Macromolecular Self- and Co-Assembled Columns Containing Tapered Groups

    DTIC Science & Technology

    1994-06-30

    ttni " O-m ’mm OFFICE OF NAVAL RESEARCH CONTRACT N00014-89-J- 1828 O R &T Code 3132080 Abstract Report #3 ISOMORPHISM WITHIN THE HEXAGONAL COLUMNAR...MESOPHASE OF MOLECULAR AND MACROMOLECULAR SELF- AND CO-ASSEMBLED COLUMNS CONTAINING TAPERED GROUPS by D. Tomazos, R . Out, J. Heck, G. Johansson, V...Containing Tapered Grouls 6. AUTHOR(S) D. Tomazos, R . Out, J. Heckc, G. Johansson, V. Percec, and M. Moeller 7. PERFORMING ORGANIZATION NAME(S) AND

  15. Effect of hygroscopicity of the metal salt on the formation and air stability of lyotropic liquid crystalline mesophases in hydrated salt-surfactant systems.

    PubMed

    Albayrak, Cemal; Barım, Gözde; Dag, Ömer

    2014-11-01

    It is known that alkali, transition metal and lanthanide salts can form lyotropic liquid crystalline (LLC) mesophases with non-ionic surfactants (such as CiH2i+1(OCH2CH2)jOH, denoted as CiEj). Here we combine several salt systems and show that the percent deliquescence relative humidity (%DRH) value of a salt is the determining parameter in the formation and stability of the mesophases and that the other parameters are secondary and less significant. Accordingly, salts can be divided into 3 categories: Type I salts (such as LiCl, LiBr, LiI, LiNO3, LiClO4, CaCl2, Ca(NO3)2, MgCl2, and some transition metal nitrates) have low %DRH and form stable salt-surfactant LLC mesophases in the presence of a small amount of water, type II salts (such as some sodium and potassium salts) that are moderately hygroscopic form disordered stable mesophases, and type III salts that have high %DRH values, do not form stable LLC mesophases and leach out salt crystals. To illustrate this effect, a large group of salts from alkali and alkaline earth metals were investigated using XRD, POM, FTIR, and Raman techniques. Among the different salts investigated in this study, the LiX (where X is Cl(-), Br(-), I(-), NO3(-), and ClO4(-)) and CaX2 (X is Cl(-), and NO3(-)) salts were more prone to establish LLC mesophases because of their lower %DRH values. The phase behavior with respect to concentration, stability, and thermal behavior of Li(I) systems were investigated further. It is seen that the phase transitions among different anions in the Li(I) systems follow the Hofmeister series.

  16. Crystallizing Membrane Proteins in the Lipidic Mesophase. Experience with Human Prostaglandin E2 Synthase 1 and an Evolving Strategy

    PubMed Central

    2015-01-01

    The lipidic mesophase or in meso method for crystallizing membrane proteins has several high profile targets to its credit and is growing in popularity. Despite its success, the method is in its infancy as far as rational crystallogenesis is concerned. Consequently, significant time, effort, and resources are still required to generate structure-grade crystals, especially with a new target type. Therefore, a need exists for crystallogenesis protocols that are effective with a broad range of membrane protein types. Recently, a strategy for crystallizing a prokaryotic α-helical membrane protein, diacylglycerol kinase (DgkA), by the in meso method was reported (Cryst. Growth. Des.2013, 13, 2846−2857). Here, we describe its application to the human α-helical microsomal prostaglandin E2 synthase 1 (mPGES1). While the DgkA strategy proved useful, significant modifications were needed to generate structure-quality crystals of this important therapeutic target. These included protein engineering, using an additive phospholipid in the hosting mesophase, performing multiple rounds of salt screening, and carrying out trials at 4 °C in the presence of a tight binding ligand. The crystallization strategy detailed here should prove useful for generating structures of other integral membrane proteins by the in meso method. PMID:24803849

  17. Anodic performance and mechanism of mesophase-pitch-derived carbons in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Mochida, Isao; Ku, Cha-Hun; Yoon, Seong-Ho; Korai, Yozo

    The anodic performance of soft carbons prepared from synthetic mesophase pitches by heat-treatment at 500 to 1200°C are investigated in order to clarify their mechanism for the insertion of lithium ions. It is found that the insertion mechanism for soft carbon heat-treated at low temperatures is divided into the following three cases: (i) lithium ions partially charge transferred on the surface of hexagonal planes or in the unstacked carbon layers to be charged and discharged at 0.25 to 0.8 V (Type I); (ii) intercalated into carbon layers up to a higher stage to be charged and discharged at 0.0 to 0.25 V (Type II); (iii) inserted into the microspaces located at the edges of carbon clusters to be charged at 0.0 to 0.1 V and discharged at 0.8 to 2.0 V (Type III). Lithium ions of Types I and II are charged and discharged reversibly, hence, the capacity is stable with cycling. By contrast, the capacity of Type III ions decreases gradually with cycle number. The irreversible charge-discharge and poor cycle stability of Type III ions suggest some chemical reactions during charge-discharge that increase the discharge potential and modify the carbon structure. Bonding of carbon planes at facing edges in the anisotropic carbon may be responsible for the poor cycle stability. The capacity of Type II ions increases gradually with heat-treatment which graphitizes carbon to allow intercalation. By contrast, the capacities of Types I and III ions are decreased gradually and sharply, respectively, by heat-treatment. The progress of graphitization densifies the carbon and reduces the free surface of the hexagonal sheet and the charging to such sites. The performance of Type III ions reflects the characteristic of anisotropic carbon in which the clusters are aligned to have more faced edges than those in isotropic carbon. The heat-treatment combines the edges to enlarge considerably the hexagonal plane in this temperature range.

  18. NMR and Raman spectroscopy monitoring of proton/deuteron exchange in aqueous solutions of ionic liquids forming hydrogen bond: a role of anions, self-aggregation, and mesophase formation.

    PubMed

    Klimavicius, Vytautas; Gdaniec, Zofia; Kausteklis, Jonas; Aleksa, Valdemaras; Aidas, Kestutis; Balevicius, Vytautas

    2013-09-05

    The H/D exchange process in the imidazolium-based room temperature ionic liquids (RTILs) 1-decyl-3-methyl-imidazolium bromide- and chloride ([C10mim][Br] and [C10mim][Cl]) in D2O solutions of various concentrations was studied applying (1)H, (13)C NMR, and Raman spectroscopy. The time dependencies of integral intensities in NMR spectra indicate that the H/D exchange in [C10mim][Br] at very high dilution (10(-4) mole fraction of RTIL) runs only slightly faster than in [C10mim][Cl]. The kinetics of this process drastically changes above critical aggregation concentration (CAC). The time required to reach the apparent reaction saturation regime in the solutions of 0.01 mole fraction of RTIL was less 10 h for [C10mim][Br], whereas no such features were seen for [C10mim][Cl] even tens of days after the sample was prepared. The H/D exchange was not observed in the liquid crystalline gel mesophase. The role of anions, self-aggregation (micellization), and mesophase formation has been discussed. Crucial influence of Br(-) and Cl(-) anions on the H/D exchange rates above CAC could be related to the short-range ordering and molecular microdynamics, in particular that of water molecules. The concept of the conformational changes coupled with the H/D exchange in imidazolium-based ionic liquids with longer hydrocarbon chains can be rejected in the light of (13)C NMR experiment. The revealed changes in (13)C NMR spectra are caused by the secondary ((13)C) isotope effects not being the signal shifts due to the conformational trans-gauche transition.

  19. Characterization of Lipid-Templated Silica and Hybrid Thin Film Mesophases by Grazing Incidence Small-Angle X-ray Scattering

    PubMed Central

    Dunphy, Darren R.; Alam, Todd M.; Tate, Michael P.; Hillhouse, Hugh W.; Smarsly, Bernd; Collord, Andrew D.; Carnes, Eric; Baca, Helen K.; Köhn, Ralf; Sprung, Michael; Wang, Jin; Brinker, C. Jeffrey

    2009-01-01

    The nanostructure of silica and hybrid thin film mesophases templated by phospholipids via an evaporation-induced self-assembly (EISA) process was investigated by grazing-incidence small-angle X-ray scattering (GISAXS). Diacyl phosphatidylcholines with two tails of 6 or 8 carbons were found to template 2D hexagonal mesophases, with the removal of lipid from these lipid/silica films by thermal or UV/O3 processing resulting in a complete collapse of the pore volume. Monoacyl phosphatidylcholines with single tails of 10–14 carbons formed 3D micellular mesophases; the lipid was found to be extractable from these 3D materials, yielding a porous material. In contrast to pure lipid/silica thin film mesophases, films formed from the hybrid bridged silsesquioxane precursor bis(triethoxysilyl)ethane exhibited greater stability toward (both diacyl and monoacyl) lipid removal. Ellipsometric, FTIR, and NMR studies show that the presence of phospholipid suppresses siloxane network formation, while actually promoting condensation reactions in the hybrid material. 1D X-ray scattering and FTIR data were found to be consistent with strong interactions between lipid headgroups and the silica framework. PMID:19496546

  20. 7Li-nuclear magnetic resonance observations of lithium insertion into coke carbon modified with mesophase-pitch

    NASA Astrophysics Data System (ADS)

    Sato, Yuichi; Tanuma, Ken-ichi; Takayama, Toshio; Kobayakawa, Koichi; Kawai, Takanobu; Yokoyama, Akira

    Lithium intercalation into coke carbon modified with mesophase-pitch and heat-treated at 800, 1000, and 3000°C was observed using solid-state 7Li-nuclear magnetic resonance ( 7Li-NMR) spectroscopy. It was found that the fully lithiated state charged to 0 V in the modified coke heat-treated at 3000°C showed a peak at about 45 ppm; on the other hand, two peaks appeared at about 45 and 16-17 ppm in the modified coke heat-treated below 1000°C. The peak appearing at 45 ppm indicated that Li-GIC is present in the first stage, and the peak at about 16-17 ppm indicated that the lithium stored in the modified part has an ionic character greater than in the coke part and is not a lithium cluster. The lithiated states charged to 0.1 and 0.2 V and discharged to 0.1, 0.2 and 1.5 V from the charged state (0 V) are also described.

  1. Characteristics of boron doped mesophase pitch-based carbon fibers as anode materials for lithium secondary cells

    SciTech Connect

    Tamaki, Toshio; Kawamura, Toshifumi; Yamazaki, Yoshinori

    1998-07-01

    Mesophase pitch-based Carbon Fibers(MCF) have been investigated as anode materials for lithium secondary cells by examining their physical and electrochemical properties. Discharge capacity and initial charge-discharge efficiency of the materials were studied in relation to the heat treatment temperatures of MCF. MCF heat treated at about 3,000 C gave high discharge capacity over 310mAh/g, good efficiency (93%) and superior current capability of 600mA/g (6mA/cm2). On the other hand, to improve the battery capacity, Boron was doped to the fiber about several {degree} by adding B{sub 4}C to the pre-carbonized milled fibers and then heat-treated up to 3,000 C in Ar. Then heat treated at 2,500 C under vacuum condition to remove remained B{sub 4}C. The structure of Boron-doped fibers was characterized and compared with that of non-doped standard fibers, and also Li ion battery performances are evaluated. The Boron-doped MCF indicated improvement in graphitization and increased discharge capacity as high as 360mAh/g. The voltammograms of both fibers are different from each other. The cell mechanism is discussed based on the unique structure of Boron-doping to the MCF is very effective for the battery performance.

  2. A Model of Chevrons in Smectic C^* Liquid Crystals: Uniform and Twisted ``Soliton'' States

    NASA Astrophysics Data System (ADS)

    Limat, Laurent

    1995-06-01

    We consider a simplified model of the chevron structure observed in thin cells of ferroelectric smectic liquid crystals, based on a generalization of the “uniaxial” (or “nematic”) approximation of orientation elasticity. This model allows for the conciliation of the continuous nature of the layers with the matching conditions postulated by Clark, and takes large rotations of the c-director into account. When the layer tilt angle is small compared to the molecular cone angle, we show that the structure of the “uniform” states reduces to the “soliton” solution found by Nakagawa. Within the same limit “twisted” states are investigated by a perturbation calculation and by qualitative energy considerations. The results suggest the existence of asymmetrical c-director distributions similar to those observed in recent experiments: in these states, the c-director splay remains mainly localized in one half of the cell, the increase of splay energy being compensated by a reduction of the “folding energy” localized in the chevron core. On discute un modèle simplifié de la structure en chevron observée dans les cristaux liquides smectiques ferroélectriques en cellules minces, basé sur une légère généralisation de l'approximation “uniaxiale” (ou “nématique”) de l'élasticité d'orientation. Ce modèle permet de réconcilier la nature continue des couches avec les conditions de raccordement postulées par Clark et prend en compte de fortes rotations de la projection du directeur sur le plan des couches. On montre que lorsque l'angle d'inclinaison des couches est faible devant l'angle du cône moléculaire, la structure, des états “uniformes” est donnée par la solution de type “soliton” découverte par Nakagawa. Dans la même limite, on étudie les états “tordus” par un calcul de perturbation complété par des arguments énergétiques plus qualitatifs. Ces deux approches suggèrent l'existence de distributions asymétriques de la torsion du directeur moléculaire similaires à celles observées dans des expériences récentes: dans ces états, la torsion se localiserait dans une demi-épaisseur de cellule, l'augmentation d'énergie étant compensée par une réduction de l'énergie de coeur du chevron.

  3. Effect of Mesophase Order on the Dynamics of Side Group Liquid Crystalline Polymers

    SciTech Connect

    Auad, M.L.; Kempe, M.D.; Kornfield, J.A.; Rendon, S.; Burghardt, W.R.; Yoon, K.

    2010-07-13

    Rheology and X-ray scattering were employed to probe the viscoelastic properties and structural transitions of model cyano-biphenyl-based side-group liquid-crystalline polymers (SGLCPs) with molecular weights ranging from 91 to 1900 kg/mol. Temperature-dependent rheological data show a rapid change in dynamics over a small temperature range. Small-angle X-ray scattering reveals these changes to be associated with an isotropic to smectic transition with an appreciable biphasic region. The presence of a biphasic region is attributed to inhomogeneity in chain structure resulting from incomplete attachment of mesogens to every monomeric unit in the SGLCP polymer. While isotropic and smectic phase data may be separately time-temperature shifted to create master curves for the individual phases, we argue against attempts to achieve superposition between the two phases in the high-frequency regime, since smectic ordering may not simply slow the dynamics but also increase the modulus of the sample. Molecular weight has a strong influence on rheology in the isotropic phase, where an entanglement plateau emerges; however, the smectic-phase rheology is dominated by the layer structure and is fairly insensitive to molecular weight.

  4. Facile synthesis of mesophase pitch/exfoliated graphite nanoplatelets nanocomposite and its application as anode materials for lithium-ion batteries

    SciTech Connect

    Yang Yishuang; Wang Chengyang; Chen Mingming; Shi Zhiqiang; Zheng Jiaming

    2010-09-15

    Mesophase pitch (MP)/exfoliated graphite nanoplatelets (GNPs) nanocomposite has been prepared by an efficient method with an initiation of graphite intercalation compounds (GIC). X-ray diffraction, optical microscopy, high-resolution transmission electron microscopy and scanning electron microscopy analysis techniques are used to characterize the samples. It is observed that GIC has exfoliated completely into GNPs during the formation of MP/GNPs nanocomposite and the GNPs are distributed uniformly in MP matrix, which represent a conductive path for a movement of electrons throughout the composites. Electrochemical tests demonstrate that the carbonized MP/GNPs nanocomposite displays higher capacity and better cycle performance in comparison with the pure carbonized MP. It is concluded that such a large improvement of electrochemical performance within the nanocomposite may in general be related to the enhanced electronic conductivity, which is achieved by good dispersion of GNPs within MP matrix and formation of a 3D network of GNPs. - Graphical abstract: Uniform mesophase pitch/exfoliated graphite nanoplatelets nanocomposite has been efficiently fabricated with an initiation of graphite intercalation compounds. The as-prepared composite electrode exhibited high electrochemical performance for Li-ion batteries.

  5. Facile synthesis of mesophase pitch/exfoliated graphite nanoplatelets nanocomposite and its application as anode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Yi-Shuang; Wang, Cheng-Yang; Chen, Ming-Ming; Shi, Zhi-Qiang; Zheng, Jia-Ming

    2010-09-01

    Mesophase pitch (MP)/exfoliated graphite nanoplatelets (GNPs) nanocomposite has been prepared by an efficient method with an initiation of graphite intercalation compounds (GIC). X-ray diffraction, optical microscopy, high-resolution transmission electron microscopy and scanning electron microscopy analysis techniques are used to characterize the samples. It is observed that GIC has exfoliated completely into GNPs during the formation of MP/GNPs nanocomposite and the GNPs are distributed uniformly in MP matrix, which represent a conductive path for a movement of electrons throughout the composites. Electrochemical tests demonstrate that the carbonized MP/GNPs nanocomposite displays higher capacity and better cycle performance in comparison with the pure carbonized MP. It is concluded that such a large improvement of electrochemical performance within the nanocomposite may in general be related to the enhanced electronic conductivity, which is achieved by good dispersion of GNPs within MP matrix and formation of a 3D network of GNPs.

  6. The structures of the crystalline phase and columnar mesophase of rhodium (II) heptanoate and of its binary mixture with copper (II) heptanoate probed by EXAFS

    NASA Astrophysics Data System (ADS)

    Inb-Elhaj, M.; Guillon, D.; Skoulios, A.; Maldivi, P.; Giroud-Godquin, A. M.; Marchon, J.-C.

    1992-12-01

    EXAFS was used to investigate the local structure of the polar spines of rhodium (II) soaps in the columnar liquid crystalline state. It was also used to ascertain the degree of blending of the cores in binary mixtures of rhodium (II) and copper (II) soaps. For the pure rhodium soaps, the columns are shown to result from the stacking of binuclear metal-metal bonded dirhodium tetracarboxylate units bonded to one another by apical ligation of the metal atom of each complex with one of the oxygen atoms of the adjacent molecule. Mixtures of rhodium (II) and copper (II) soaps give a hexagonal columnar mesophase in which pure rhodium and pure copper columns are randomly distributed.

  7. Tyrosine-Based Ionic Liquid Crystals: Switching from a Smectic A to a Columnar Mesophase by Exchange of the Spherical Counterion.

    PubMed

    Neidhardt, Manuel M; Wolfrum, Manpreet; Beardsworth, Stuart; Wöhrle, Tobias; Frey, Wolfgang; Baro, Angelika; Stubenrauch, Cosima; Giesselmann, Frank; Laschat, Sabine

    2016-11-07

    Synthetic strategies were developed to prepare l-tyrosine-based ionic liquid crystals with structural variations at the carboxylic and phenolic OH groups as well as the amino functionality. Salt metathesis additionally led to counterion variation. The liquid-crystalline properties were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS, SAXS). The symmetrical ILC chlorides bearing the same alkyl chain at both the ester and ether but either an acyclic or cyclic guanidinium group displayed enantiotropic SmA2 mesophases with phase widths of 31-88 K irrespective of the head group. It was particularly the replacement of chloride in the acyclic guanidinium ILC by hexafluorophosphate that induced a phase change from SmA2 to Colr . This phase change was attributed to a higher curvature of the interface due to the larger anion, which increased the effective head group cross-sectional area of the amphiphilic ILC. The unsymmetrical acyclic guanidinium chlorides, bearing a constant C14 ester and variable alkyl chains on the phenolic position, formed enantiotropic SmA2 phases. The derivative with the largest difference in chain lengths, however, displayed a Colr phase, resulting from discoid aggregates of the cone-shaped guanidinium chloride. The results are discussed in terms of the packing parameters, which indicate that the phase behaviour of the thermotropic tyrosine-based ILCs shows analogies to those of lyotropic liquid crystals.

  8. The phase diagram of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/sucrose in the dry state. Sucrose substitution for water in lamellar mesophases.

    PubMed

    Hentschel, M; Miethe, P; Meyer, H W

    1989-04-14

    The phase diagram of the binary system, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/sucrose, was determined by DSC. In contrast to dry DPPC, which exhibits chain melting at 342.5 K, the main feature of the DPPC/sucrose system is eutectic melting at 320 K. This was supported earlier by Crowe, J.H., Crowe, L.M. and Chapman, D. (Science 223 (1984) 701-703), who reported a drastic decrease in the chain-melting temperature of the dry lipid in the presence of some mono- and disaccharides. Electron microscopy suggests that the phase structures on either side of the phase transition are of the lamellar type. Definite sugar saturation concentrations can be derived from this phase diagram. Up to about 17 mol% sucrose, i.e., 1 mol of sucrose per 5 mol of lipid is adopted by DPPC in the low-temperature phase Lc. In the high-temperature phase Lm the saturation concentration is well above 90 mol% sucrose at 320 K (eutectic point) but decreases with increasing temperature. The lower limit of 50 mol% sucrose is reached at 455 K. At this temperature, peritectic melting of sucrose occurs. Because of some similarities in the phase diagrams of DPPC/sucrose and DPPC/water, it is possible to understand the sucrose substitution for water in dry lamellar mesophases.

  9. Electric-field-induced unwinding of ferroelectric helix in thin smectic C* layers with soft and rigid anchoring of molecules

    SciTech Connect

    Dolganov, P. V.; Zhilin, V. M. Dolganov, V. K.; Kats, E. I.

    2008-09-15

    The unwinding of a helical structure in thin films of a ferroelectric smectic liquid crystal (LC) by an external electric field has been theoretically studied using a discrete model in which every LC layer is characterized by a two-dimensional vector {xi}{sub i} (describing the orientation of molecules) and by the polarization P{sub i}. It is established that the unwinding of the LC helix in thin films significantly differs from the well-known behavior of thick samples. In particular, discrete intermediate states (differing by an integer or half-integer number of turns) are formed in thin films for both weak and strong anchoring of molecules to a substrate surface. The physical factor responsible for this behavior is the presence of near-surface regions with thicknesses below the helix pitch and the corresponding uncompensated polarization.

  10. Columnar benzoperylene-hexa- and tetracarboxylic imides and esters: synthesis, mesophase stabilisation and observation of charge-transfer interactions between electron-donating esters and electron-accepting imides.

    PubMed

    Kelber, Julien; Achard, Marie-France; Garreau-de Bonneval, Bénédicte; Bock, Harald

    2011-07-11

    Benzo[ghi]perylene 1,2,4,5,10,11-hexacarboxylic trialkylimide and dialkylimido-dialkyl ester derivatives, displaying a thermodynamically stable hexagonal columnar liquid-crystalline phase at room temperature, have been obtained by the use of previously unexplored chiral racemic α-branched alkylimide functions. One of the trialkylimides described here is the first room temperature columnar solely oligo-alkylimide-substituted arene, and thus constitutes a prototype case of self-assembling organic acceptor materials. As the related hexacarboxylic hexaesters are found to exhibit only a weak tendency to form columnar mesophases, benzo[ghi]perylene 1,2,5,10-tetracarboxylic tetraalkyl esters have been synthesized by regioselective oxidative Diels-Alder addition of maleic anhydride to 3,10-dicyanoperylene, and a room temperature hexagonal columnar mesophase was obtained with branched alkyl chains. The acceptor-type electronic properties of the tri- and diimides have been found to be considerably more pronounced than those of the hexa- and tetracarboxylic esters, and to approach those of the prototype acceptor material C(60). The formation of bathochromically absorbing donor-acceptor complexes was observed with a di- or triimide as acceptor and a tetraester as donor, but not with a hexaester as donor. Exploiting the non-negligible differences in reduction and oxidation potentials between all four types of materials, the minimum HOMO energy difference necessary for charge-transfer-complex formation has been determined to lie between 0.29 and 0.35 eV.

  11. Revealing Rembrandt

    PubMed Central

    Parker, Andrew J.

    2014-01-01

    The power and significance of artwork in shaping human cognition is self-evident. The starting point for our empirical investigations is the view that the task of neuroscience is to integrate itself with other forms of knowledge, rather than to seek to supplant them. In our recent work, we examined a particular aspect of the appreciation of artwork using present-day functional magnetic resonance imaging (fMRI). Our results emphasized the continuity between viewing artwork and other human cognitive activities. We also showed that appreciation of a particular aspect of artwork, namely authenticity, depends upon the co-ordinated activity between the brain regions involved in multiple decision making and those responsible for processing visual information. The findings about brain function probably have no specific consequences for understanding how people respond to the art of Rembrandt in comparison with their response to other artworks. However, the use of images of Rembrandt's portraits, his most intimate and personal works, clearly had a significant impact upon our viewers, even though they have been spatially confined to the interior of an MRI scanner at the time of viewing. Neuroscientific studies of humans viewing artwork have the capacity to reveal the diversity of human cognitive responses that may be induced by external advice or context as people view artwork in a variety of frameworks and settings. PMID:24795552

  12. Molecular Engineering of Liquid Crystal Polymers by Lining Polymerization. 16. Tailor-Made sC* Mesophase in Copolymers of 4-((S-(-)-2- Methyl-1-Butyl)Oxycarbonyl)-4’-omega-Oxyalkyl-1-Vinyl Ether)Biphenyl With Undecanyl and Octyl Alkyl Groups

    DTIC Science & Technology

    1991-10-30

    4-{ [S-(-)-2-Methyl- l -Butyl]Oxycarbonyl) -4’-(W-Oxyalkyl- 1 -Vinyl Ethcr)Biphenyl with Undecanyl and Octyl Alkyl Groups 12. PERSONAL AUTHOR(S...polymerization lower than 40 and polydispersities 1.15 were synthesized and characterized by differential scanning calorimetry (DSC) and thermal optical...an enantiotropic unidentified sx mesophase. Copolymers of 14-8 with 4-{[S(-)2-methyl- l -butyll oxycarbonyl)- 4 ’-( l - oxyuindecanyl-lI-vinyl ether

  13. Modeling the field control of the surface electroclinic effect near continuous and first-order smectic-A* to smectic-C* transitions.

    PubMed

    Zappitelli, Kara; Hipolite, Dana N; Saunders, Karl

    2014-02-01

    We present and analyze a model for the combination of bulk and surface electroclinic effects in the smectic-A* (Sm-A*) phase near a Sm-A*-Sm-C* transition. As part of our analysis we calculate the dependence of the surface tilt on external electric field and show that it can be eliminated, or even reversed from its zero-field value, as demonstrated in previous experimental work on a system (W415) with a continuous Sm-A*-Sm-C* transition. We also analyze, for the first time, the combination of bulk and surface electroclinic effects in systems with a first-order Sm-A*-Sm-C* transition. The variation of surface tilt with electric field in this case is much more dramatic, with discontinuities and hysteresis. With regard to technological, e.g., display, applications, this could be a feature to be avoided or potentially exploited. Near each type of Sm-A*-Sm-C* transition we obtain the temperature dependence of the field required to eliminate surface tilt. Additionally, we analyze the effect of varying the system's enantiomeric excess, showing that it strongly affects the field dependence of surface tilt, in particular, near a first-order Sm-A*-Sm-C* transition. In this case, increasing enantiomeric excess can change the field dependence of surface tilt from continuous to discontinuous. Our model also allows us to calculate the variation of layer spacing in going from surface to bulk, which in turn allows us to estimate the strain resulting from the difference between the surface and bulk layer spacing. We show that for certain ranges of applied electric field, this strain can result in layer buckling, which reduces the overall quality of the liquid crystal cell. For de Vries materials, with small tilt-induced change in layer spacing, the induced strain for a given surface tilt should be smaller. However, we argue that this may be offset by the fact that de Vries materials, which typically have Sm-A*-Sm-C* transitions near a tricritical point, will generally have larger surface tilt.

  14. Formation of smectic phases in binary liquid crystal mixtures with a huge length ratio

    PubMed Central

    Knecht, Friederike; Hartley, C Scott; Roberts, Jeffrey C; Lemieux, Robert P; Giesselmann, Frank

    2012-01-01

    Summary A system of two liquid-crystalline phenylpyrimidines differing strongly in molecular length was studied. The phase diagram of these two chemically similar mesogens, with a length ratio of 2, was investigated, and detailed X-ray diffraction and electrooptical measurements were performed. The phase diagram revealed a destabilization of the nematic phase, which is present in the pure short compound, while the smectic state was stabilized. The short compound forms smectic A and smectic C phases, whereas the longer compound forms a broad smectic C phase and a narrow higher-ordered smectic phase. Nevertheless, in the mixtures, the smectic C phase is destabilized and disappears rapidly, whereas smectic A is the only stable phase observed over a broad concentration range. In addition, the smectic translational order parameters as well as the tilt angles of the mixtures are reduced. The higher-ordered smectic phase of the longer mesogen was identified as a smectic F phase. PMID:23019439

  15. Mesomorphic and dielectric properties of esters useful for formulation of nematic mixtures for dual frequency addressing system

    NASA Astrophysics Data System (ADS)

    Ziobro, D.; Kula, P.; Dziaduszek, J.; Filipowicz, M.; DĄbrowski, R.; Parka, J.; Czub, J.; Urban, S.; Wu, S. T.

    2009-03-01

    Mesomorphic and dielectric properties of three homologous series of two and three ring fluorosubstituted esters are described. They are 4-cyano-3-fluorophenyl 4-alkyloxy-2-fluorobenzoates, 4-cyano-3-fluorophenyl 4-(4-alkylbenzoyloxy)-2-fluorobenzoates and 3-fluoro-4-cyanophenyl, or 3-fluoro-4-isothiocyanatophenyl or 3,4-difluorophenyl 4'-alkyl-2,3-difluoro-biphenyl-4-carboxylates. The compounds exhibit the nematic mesophase accompanied by the smectic A or smectic C mesophase in some cases. Most of them show strong dependence of the dielectric anisotropy Δɛ upon frequency, at low frequencies Δɛ reaches a value ˜200, while at high frequencies a small negative dielectric anisotropy appears.

  16. Revealing the potential of Didodecyldimethylammonium bromide as efficient scaffold for fabrication of nano liquid crystalline structures.

    PubMed

    Kanwar, Rohini; Kaur, Gurpreet; Mehta, S K

    2016-03-01

    To exploit the potential of Didodecyldimethylammonium bromide (D12DAB) as a core lipidic constituent, an attempt was made to fabricate and optimize cationic nanostructured lipid carriers (cNLCs) using a cost-effective microemulsification methodology. Designed composition was optimized by studying the effect of different microemulsion components on D12DAB cNLCs characteristics. ​Spherical shaped D12DAB cNLCs were obtained with an average size of ∼160 nm and zeta potential of +30.2 mV. Differential Scanning Calorimetry (DSC) depicted the presence of thermotropic character, whereas polarized optical microscopy confirmed the mesophase like behavior of D12DAB based cNLCs. In addition, hemolysis analysis revealed that the toxicity was concentration dependent as LC50 was reached at a concentration of 50 μg/mL of cNLCs. This class of cNLCs is expected to become a potent candidate for a broad spectrum of medicaments as carriers, targeting for pharmaceutical and medicinal purposes, due to the combination of a hard lipid with a soft lipid, where the liquid crystalline structure of the lipid co-exists.

  17. Shear alignment of lamellar mesophase systems

    NASA Astrophysics Data System (ADS)

    Jaju, S. J.; Kumaran, V.

    2015-11-01

    Mixtures of oil, water and surfactants form different microphases. Some of these phases, e.g. lamellar, hexagonal phases, lead to complex rheological behaviour at macroscale due to inherent anisotropy and irregularities in the microstructures. We present a comprehensive simulation study to examine the structure-rheology relationship in lamellar phase flow. At mesoscale, Reynolds number (Re), Schmidt number (Sc), Ericksen number (Er), extent of segregation between hydrophilic and hydrophobic components (r), ratio of viscosity of the two components (Δμ /μ0), and system size to layer width ratio (L / λ) complete the lamellar phase description. We have used lattice Boltzmann simulations to study a two dimensional lamellar phase system of moderate size. The domains and grain boundaries seen at low Sc are replaced by isolated edge dislocations at high Sc. The alignment mechanism does not change with changes in layer bending moduli (Er), viscosity contrast or r. Increasing segregation, increases disorder; this however does not lead to higher resistance to flow. At high Er, the shear tries homogenise the concentration field and disrupt layer formation. We see significantly higher peak viscosity at low Er at high viscosity contrast and due to defect pinning. The authors would like to thank the Department of Science and Technology, Government of India for financial support, and Supercomputer Education and Research Centre at Indian Institute of Science for the computational resources.

  18. Methods for producing mesophase pitch binder pitch

    SciTech Connect

    Lewis, I.C.

    1984-02-14

    A method of producing a pitch or a coke, comprising reacting an aromatic hydrocarbon with anhydrous AlCl/sub 3/ and an acid salt of an organic amine which acid salt reduces the activity of the AlCl/sub 3/, and is miscible with the AlCl/sub 3/ to form a molten eutectic salt mixture reactive with the aromatic hydrocarbon.

  19. Solubilization of nutraceuticals into reverse hexagonal mesophases.

    PubMed

    Amar-Yuli, Idit; Aserin, Abraham; Garti, Nissim

    2008-08-21

    The solubilization of four bioactive molecules with different polarities, in three reverse hexagonal (HII) systems has been investigated. The three HII systems were a typical reverse hexagonal composed of glycerol monooleate (GMO)/tricaprylin/water and two fluid hexagonal systems containing either 2.75 wt % Transcutol or ethanol as a fourth component. The phase behavior of the liquid crystalline phases in the presence of ascorbic acid, ascorbyl palmitate, D-alpha-tocopherol and D-alpha-tocopherol acetate were determined by small-angle X-ray scattering (SAXS) and optical microscopy. Differential scanning calorimetry (DSC) and Fourier-transform infrared (FT-IR) techniques were utilized to follow modifications in the thermal behavior and in the vibrations of different functional groups upon solubilizing the bioactive molecules. The nature of each guest molecule (in both geometry and polarity) together with the different HII structures (typical and fluids) determined the corresponding phase behavior, swelling or structural transformations and its location in the HII structures. Ascorbic acid was found to act as a chaotropic guest molecule, localized in the water-rich core and at the interface. The AP was also a chaotropic guest molecule with its head located in the vicinity of the GMO headgroup while its tail embedded close to the surfactant tail. D-alpha-tocopherol and D-alpha-tocopherol acetate were incorporated between the GMO tails; however, the D-alpha-tocopherol was located closer to the interface. Once Transcutol or ethanol was present and upon guest molecule incorporation, partial migration was detected.

  20. Shear alignment of a disordered lamellar mesophase.

    PubMed

    Kumaran, V; Raman, D S S

    2011-03-01

    The shear alignment of an initially disordered lamellar phase is examined using lattice Boltzmann simulations of a mesoscopic model based on a free-energy functional for the concentration modulation. For a small shear cell of width 8λ, the qualitative features of the alignment process are strongly dependent on the Schmidt number Sc=ν/D (ratio of kinematic viscosity and mass diffusion coefficient). Here, λ is the wavelength of the concentration modulation. At low Schmidt number, it is found that there is a significant initial increase in the viscosity, coinciding with the alignment of layers along the extensional axis, followed by a decrease at long times due to the alignment along the flow direction. At high Schmidt number, alignment takes place due to the breakage and reformation of layers because diffusion is slow compared to shear deformation; this results in faster alignment. The system size has a strong effect on the alignment process; perfect alignment takes place for a small systems of width 8λ and 16λ, while a larger system of width 32λ does not align completely even at long times. In the larger system, there appears to be a dynamical steady state in which the layers are not perfectly aligned--where there is a balance between the annealing of defects due to shear and the creation due to an instability of the aligned lamellar phase under shear. We observe two types of defect creation mechanisms: the buckling instability under dilation, which was reported earlier, as well as a second mechanism due to layer compression.

  1. How Are Preferences Revealed?

    PubMed Central

    Beshears, John; Choi, James J.; Laibson, David; Madrian, Brigitte C.

    2009-01-01

    Revealed preferences are tastes that rationalize an economic agent’s observed actions. Normative preferences represent the agent’s actual interests. It sometimes makes sense to assume that revealed preferences are identical to normative preferences. But there are many cases where this assumption is violated. We identify five factors that increase the likelihood of a disparity between revealed preferences and normative preferences: passive choice, complexity, limited personal experience, third-party marketing, and intertemporal choice. We then discuss six approaches that jointly contribute to the identification of normative preferences: structural estimation, active decisions, asymptotic choice, aggregated revealed preferences, reported preferences, and informed preferences. Each of these approaches uses consumer behavior to infer some property of normative preferences without equating revealed and normative preferences. We illustrate these issues with evidence from savings and investment outcomes. PMID:24761048

  2. Revealing power in truth

    PubMed Central

    Lee, Kelley

    2015-01-01

    Jeremy Shiffman’s editorial appropriately calls on making all forms of power more apparent and accountable, notably productive power derived from expertise and claims to moral authority. This commentary argues that relationships based on productive power can be especially difficult to reveal in global health policy because of embedded notions about the nature of power and politics. Yet, it is essential to recognize that global health is shot through with power relationships, that they can take many forms, and that their explicit acknowledgement should be part of, rather than factored out of, any reform of global health governance. PMID:25844390

  3. The Universe Revealed

    NASA Astrophysics Data System (ADS)

    Spence, Pam

    1998-10-01

    The Universe is a bewildering place to the uninitiated. The concepts and theories that govern space seem complex and often contradictory. The Universe Revealed provides the keys to unlocking the wonders of the cosmos. Elegantly written and lavishly illustrated, it begins with the Sun and stretches through our solar system into deepest space. Lucid prose, written by many of the people who have shaped our current thinking on space, and spectacular photographs make the physics of the Universe accessible and provide a solid background for understanding the most recent astronomical discoveries. Covering the most intriguing features of the cosmos, the topics discussed range from the Earth and global warming to cosmic collisions and the size of the Universe. Major sections examine the Solar System, stars, galaxies, cosmology, and the observational techniques used by astronomers, both amateur and professional. The Universe Revealed represents the collaboration of internationally renowned experts in astronomy and cosmology, with contributions from authors including David Malin, F. Duccio Macchetto, Iain Nicholson, Neil Bone, Ian Ridpath, Seth Shostak, Mike Lancaster, Steve Miller, Ken Croswell, Geoff McNamara, and Steven Young. This extraordinary blend of astronomy, astrophysics, and cosmology, will appeal to amateur and armchair astronomers alike.

  4. Gusev's Rim Revealed

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA's Mars Exploration Rover Spirit took this panoramic camera image on sol 91 (April 5, 2004). Spirit is looking to the southeast, and through the martian haze has captured the rim of Gusev Crater approximately 80 kilometers (49.7 miles) away on the horizon.

    The right side of this image reveals the portion of the crater edge that descends into the mouth of Ma'adim Vallis, a channel that opens into Gusev Crater. Spirit is currently traveling toward the informally named 'Columbia Hills,' which lie to the left of the region pictured here.

    This image is similar to a panoramic camera image taken on sol 68, but Gusev's ridge is more visible here because the atmospheric dust caused by winter dust storms has settled. Scientists expect to get even clearer images than this one in upcoming sols.

    This image has been modified to make the crater rim more visible.

  5. Ancient River revealed

    NASA Astrophysics Data System (ADS)

    Recent flights of the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) mission aboard the space shuttle Endeavour discovered a previously unknown branch of an ancient river. The images, released at AGU's Spring Meeting, show the river channel buried under thousands of years worth of windblown sand in a region of North Africa's Sahara Desert near the Kufra Oasis in southeast Libya, centered at 23.3°N latitude, 22.9°E longitude. The image from the flight last October reveals a system of old, now inactive stream valleys, called “paleodrainage systems,” which carried running water northward across the Sahara during periods of wetter climate.

  6. Structure and elastic properties of smectic liquid crystalline elastomer films.

    PubMed

    Stannarius, R; Köhler, R; Dietrich, U; Lösche, M; Tolksdorf, C; Zentel, R

    2002-04-01

    Mechanical measurements, x-ray investigations, and optical microscopy are employed to characterize the interplay of chemical composition, network topology, and elastic response of smectic liquid crystalline elastomers (LCEs) in various mesophases. Macroscopically ordered elastomer films of submicrometer thicknesses were prepared by cross linking freely suspended smectic polymer films. The cross-linked material preserves the mesomorphism and phase transitions of the precursor polymer. The elastic response of the smectic LCE is entropic, and the corresponding elastic moduli are of the order of MPa. In the tilted ferroelectric smectic-C* phase, the network structure plays an important role. Due to the coupling of elastic network deformations to the orientation of the mesogenic groups in interlayer cross-linked materials (mesogenic cross-linker units), the stress-strain characteristics is found to differ qualitatively from that in the other phases.

  7. Photochromism and diffraction grating in cyanoazobenzene polymer films

    NASA Astrophysics Data System (ADS)

    Serwadczak, M.; Wübbenhorst, M.; Kucharski, S.

    2006-08-01

    Two series of photochromic copolymathacrylates containing cyanoazobenzene chromophores as side chains were described. The series with shorter ethylene spacer between mesogen and main polymethacrylate chain was amorphous, whereas the second one with longer ethoxyethylene spacer was liquid crystalline forming smectic C mesophase above Tg. The materials were deposited on glass substrates via spin coating and casting technique to provide thin transparent films. The reversible change of refractive index of the films on illumination with white light was determined by ellipsometry. The difference of real part of the refractive index of the sample was in the range 0.0067-0.0210 depending on the polymer. Formation of diffraction grating was achieved by two beam coupling arrangement using a 532 nm laser diode . The diffraction efficiency for the first order diffraction was in the range of 1.5-2.1% for the homopolymers.

  8. Titan Casts Revealing Shadow

    NASA Astrophysics Data System (ADS)

    2004-05-01

    A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in

  9. Revealing the Beast Within

    NASA Astrophysics Data System (ADS)

    2003-07-01

    Deeply Embedded Massive Stellar Clusters Discovered in Milky Way Powerhouse Summary Peering into a giant molecular cloud in the Milky Way galaxy - known as W49 - astronomers from the European Southern Observatory (ESO) have discovered a whole new population of very massive newborn stars . This research is being presented today at the International Astronomical Union's 25th General Assembly held in Sydney, Australia, by ESO-scientist João Alves. With the help of infrared images obtained during a period of excellent observing conditions with the ESO 3.5-m New Technology Telescope (NTT) at the La Silla Observatory (Chile), the astronomers looked deep into this molecular cloud and discovered four massive stellar clusters, with hot and energetic stars as massive as 120 solar masses. The exceedingly strong radiation from the stars in the largest of these clusters is "powering" a 20 light-year diameter region of mostly ionized hydrogen gas (a "giant HII region"). W49 is one of the most energetic regions of star formation in the Milky Way. With the present discovery, the true sources of the enormous energy have now been revealed for the first time, finally bringing to an end some decades of astronomical speculations and hypotheses. PR Photo 21a/03 : Colour Composite of W49A (NTT+SOFI). PR Photo 21b/03 : Radio and Near-Infrared Composite of W49A Giant molecular clouds Stars form predominantly inside Giant Molecular Clouds which populate our Galaxy, the Milky Way. One of the most prominent of these is W49 , which has a mass of a million solar masses. It is located some 37,000 light-years away and is the most luminous star-forming region known in our home galaxy: its luminosity is several million times the luminosity of our Sun. A smaller region within this cloud is denoted W49A - this is one of the strongest radio-emitting areas known in the Galaxy . Massive stars are excessive in all ways. Compared to their smaller and ligther brethren, they form at an Olympic speed and

  10. Novel biphenyl-substituted 1,2,4-oxadiazole ferroelectric liquid crystals: synthesis and characterization

    PubMed Central

    Subrao, Mahabaleshwara; Potukuchi, Dakshina Murthy; Sharada Ramachandra, Girish; Bhagavath, Poornima; Bhat, Sangeetha G

    2015-01-01

    Summary Two novel series of unsymmetrically substituted 1,2,4-oxadiazole viz., R.Ox.C*Cn compounds are synthesized and characterized. An optically active, (S)-(+)-methyl 3-hydroxy-2-methylpropionate is used to introduce a chiral center in the molecule. A biphenyl moiety prepared by Suzuki coupling reaction is directly attached to the oxadiazole core at C-5 position. Investigations for the phase behavior revealed that the series with a benzyl group on one end of the oxadiazole core exhibits an 1D orthogonal smectic-A phase while the second series with dodecyl flexible end chain shows orthogonal smectic-A and tilted chiral smectic-C (SmC*) phases over a wide range of temperatures. The smectic-C phase exhibits ferroelectric (FE) polarization switching. The mesomorphic thermal stabilities of these compounds are discussed in the domain of the symmetry and the flexibility of the alkyloxy end chain length attached to the chiral center. PMID:25815075

  11. [Nephrocutaneous fistula revealing xanthogranulomatous pyelonephritis].

    PubMed

    Scotté, M; Sibert, L; Soury, P; Lebret, T; Gobet, F; Grise, P; Tenière, P

    1993-01-01

    A patient presented with a reno-cutaneous fistula revealing a xanthogranulomatous pyelonephritis secondary to staghorn calculus. Total nephrectomy was necessary because of renal destruction. This treatment allowed closure of the fistula and a good clinical result.

  12. Liquid-crystalline nanoparticles: Hybrid design and mesophase structures

    PubMed Central

    Greget, Romain; Dominguez, Cristina; Nagy, Zsuzsanna T; Guillon, Daniel; Gallani, Jean-Louis

    2012-01-01

    Summary Liquid-crystalline nanoparticles represent an exciting class of new materials for a variety of potential applications. By combining supramolecular ordering with the fluid properties of the liquid-crystalline state, these materials offer the possibility to organise nanoparticles into addressable 2-D and 3-D arrangements exhibiting high processability and self-healing properties. Herein, we review the developments in the field of discrete thermotropic liquid-crystalline nanoparticle hybrids, with special emphasis on the relationship between the nanoparticle morphology and the nature of the organic ligand coating and their resulting phase behaviour. Mechanisms proposed to explain the supramolecular organisation of the mesogens within the liquid-crystalline phases are discussed. PMID:22509204

  13. The structure of mesophase fiber-forming pitches

    SciTech Connect

    Kirda, V.S.; Khrenkova, T.M.; Zamanova, L.V.; Nikolaeva, L.V.; Fedoseev, S.D.

    1993-12-31

    The structural features of several pitches, obtained from cracking residues and a pitch-like material, have been investigated as to their fiber-forming ability. The residues were obtained by heat treatments of cracking residues of a residual and two types of distillates. Infrared spectroscopy and x-ray diffraction results are discussed.

  14. Why GPCRs behave differently in cubic and lamellar lipidic mesophases

    PubMed Central

    2012-01-01

    Recent successes in the crystallographic determination of structures of transmembrane proteins in the G protein-coupled receptor (GPCR) family have established the lipidic cubic phase (LCP) environment as the medium of choice for growing structure-grade crystals by the method termed “in meso”. The understanding of in meso crystallogenesis is currently at a descriptive level. To enable an eventual quantitative, energy-based description of the nucleation and crystallization mechanism, we have examined the properties of the lipidic cubic phase system and the dynamics of the GPCR rhodopsin reconstituted into the LCP with coarse-grained molecular dynamics simulations with the Martini force-field. Quantifying the differences in the hydrophobic/hydrophilic exposure of the GPCR to lipids in the cubic and lamellar phases, we found that the highly curved geometry of the cubic phase provides more efficient shielding of the protein from unfavorable hydrophobic exposure, which leads to a lesser hydrophobic mismatch and less unfavorable hydrophobic–hydrophilic interactions between the protein and lipid–water interface in the LCP, compared to the lamellar phase. Since hydrophobic mismatch is considered a driving force for oligomerization, the differences in exposure mismatch energies between the LCP and the lamellar structures suggest that the latter provide a more favorable setting in which GPCRs can oligomerize as a prelude to nucleation and crystal growth. These new findings lay the foundation for future investigations of in meso crystallization mechanisms related to the transition from the LCP to the lamellar phase and studies aimed at an improved rational approach for generating structure-quality crystals of membrane proteins. PMID:22931253

  15. Thermally induced fluid reversed hexagonal (H(II)) mesophase.

    PubMed

    Amar-Yuli, Idit; Wachtel, Ellen; Shalev, Deborah E; Moshe, Hagai; Aserin, Abraham; Garti, Nissim

    2007-12-06

    In the present study we characterized the microstructures of the Lc and HII phases in a glycerol monooleate (GMO)/tricaprylin (TAG)/water mixture as a function of temperature. We studied the factors that govern the formation of a low-viscosity HII phase at relatively elevated temperatures (>35 degrees C). This phase has very valuable physical characteristics and properties. The techniques used were differential scanning calorimetry (DSC), wide- and small-angle X-ray scattering (WAXS and SAXS, respectively), NMR (self-diffusion and (2)H NMR), and Fourier transform infrared (FTIR) spectroscopies. The reverse hexagonal phase exhibited relatively rapid flow of water in the inner channels within the densely packed cylindrical aggregates of GMO with TAG molecules located in the interstices. The existence of two water diffusion peaks reflects the existence of both mobile water and hydration water at the GMO-water interface (hydrogen exchange between the GMO hydroxyls and water molecules). Above 35 degrees C, the sample became fluid yet hexagonal symmetry was maintained. The fluidity of the HII phase is explained by a significant reduction in the domain size and also perhaps cylinder length. This phenomenon was characterized by higher mobility of the GMO, lower mobility of the water, and a significant dehydration process.

  16. Two Unique Glioma Subtypes Revealed.

    PubMed

    Poh, Alissa

    2016-04-01

    A comprehensive analysis of 1,122 diffuse glioma samples from The Cancer Genome Atlas has revealed two new subtypes of this common brain cancer, with molecular and clinical features that diverge from the norm. The study findings also support the use of DNA methylation profiles to improve glioma classification and treatment.

  17. Ischemic Colitis Revealing Polyarteritis Nodosa

    PubMed Central

    Hamzaoui, Amira; Litaiem, Noureddine; Smiti Khanfir, M.; Ayadi, Sofiene; Nfoussi, Haifa; Houman, M. H.

    2013-01-01

    Ischemic colitis is one of the most common intestinal ischemic injuries. It results from impaired perfusion of blood to the bowel and is rarely caused by vasculitis. We report a case of ischemic colitis revealing polyarteritis nodosa (PAN) in a 55-year-old man. Histological examination of the resected colon led to the diagnosis of PAN. PMID:24382967

  18. [Seizures revealing phosphocalcic metabolism abnormalities].

    PubMed

    Hmami, F; Chaouki, S; Benmiloud, S; Souilmi, F Z; Abourazzak, S; Idrissi, M; Atmani, S; Bouharrou, A; Hida, M

    2014-01-01

    Hypocalcemia due to hypoparathyroidism produces a broad spectrum of clinical manifestations, but overt symptoms may be sparse. One unusual presentation is onset or aggravation of epilepsy in adolescence revealing hypoparathyroidism. This situation can lead to delayed diagnosis, with inefficacity of the antiepileptic drugs. We report five cases of adolescence-onset epilepsy with unsuccessful antiepileptic therapy, even with gradually increasing dose. Physical examination revealed signs of hypocalcemia, confirmed biologically. Full testing disclosed the origin of the seizures: hypoparathyroidism in three patients and pseudohypoparathyroidism in the other two. In four of five patients, computed tomography showed calcification of the basal ganglia, defining Fahr's syndrome. The patients were treated with oral calcium and active vitamin D (1-alphahydroxy vitamin D3). Seizure frequency progressively decreased and serum calcium levels returned to normal. These cases illustrate the importance of the physical examination and of routine serum calcium assay in patients with new-onset epileptic seizures in order to detect hypocalcemia secondary to hypoparathyroidism.

  19. Revealing the microstructure of materials

    NASA Technical Reports Server (NTRS)

    Nelson, James A.

    1990-01-01

    The objectives are to demonstrate how the microstructure of materials may be revealed by abrasive polishing and chemical etching, and to illustrate how microstructural information is used to monitor manufacturing processes, provide in-depth inspection, and perform failure analysis. Microstructural analysis is the procedure used to reveal the internal microstructural details of a material or part by sectioning and polishing the cut surface so that it may be examined under a suitable microscope. A printed wiring board was selected as the test material because it contains both metals and nonmetals that have distinctive microstructures, and because this technique is used throughout the electronic industry as a key quality control tool. The three principle component materials in printed circuit boards are glass/epoxy laminates faced with copper foil; copper, deposited by both electroless and electrolytic plating; and tin/lead solder. Sample preparation, mounting, grinding, polishing, and examination and analysis are discussed.

  20. Investigation on Thermal and Optical Properties of Hydrogen-Bonded Binary Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Ranjeeth kumar, T.; Sundaram, S.; Vasanthi, T.; Subhasri, P.; Chitravel, T.; Senthil, T. S.; Jayaprakasam, R.; Vijayakumar, V. N.

    2016-12-01

    A homologous series of hydrogen-bonded liquid crystals (HBLCs) are synthesized and characterized. Intermolecular hydrogen bonding occurs between 4-methoxycinnamic acid (4MCA) and p-n-alkyloxy benzoic acids (nOBA, where n = 3, 7 to 12). These binary complexes have been obtained by following well-designed synthesis route. The subsequent binary complexes have been characterized by polarizing optical thermal microscopy (POM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The present work explains the details of the association between the mesogenic phase behavior and H-bonding in the homologous series of 4MCA + nOBA. Nematic phase is interrelated with the closed dimers between acid molecules through the formation of strong hydrogen bonds. But, high concentrations are linked to the manifestation of smectic phases that disturb the local order of the nematic phase. As a result, the higher-order mesophases are observed in the present binary complex series. The inclusion of nematic LC (4MCA) in the nOBA alters the melting temperature and the clearing temperature as lower than those of the individual. Also, the wide mesophase regions of the present series are identified compared to those of the constituent mesogens. The optical tilt angle of binary mixtures for smectic C phase and thermal stability factors of the mesogenic phases have been discussed.

  1. Archimedes: Accelerator Reveals Ancient Text

    SciTech Connect

    Bergmann, Uwe

    2004-02-24

    Archimedes (287-212 BC), who is famous for shouting 'Eureka' (I found it) is considered one of the most brilliant thinkers of all times. The 10th-century parchment document known as the 'Archimedes Palimpsest' is the unique source for two of the great Greek's treatises. Some of the writings, hidden under gold forgeries, have recently been revealed at the Stanford Synchrotron Radiation Laboratory at SLAC. An intense x-ray beam produced in a particle accelerator causes the iron in original ink, which has been partly erased and covered, to send out a fluorescence glow. A detector records the signal and a digital image showing the ancient writings is produced. Please join us in this fascinating journey of a 1,000-year-old parchment from its origin in the Mediterranean city of Constantinople to a particle accelerator in Menlo Park.

  2. Revealing Non-Covalent Interactions

    PubMed Central

    Johnson, Erin R.; Keinan, Shahar; Mori-Sánchez, Paula; Contreras-García, Julia; Cohen, Aron J.; Yang, Weitao

    2010-01-01

    Molecular structure does not easily identify the intricate non-covalent interactions that govern many areas of biology and chemistry, including design of new materials and drugs. We develop an approach to detect non-covalent interactions in real space, based on the electron density and its derivatives. Our approach reveals underlying chemistry that compliments the covalent structure. It provides a rich representation of van der Waals interactions, hydrogen bonds, and steric repulsion in small molecules, molecular complexes, and solids. Most importantly, the method, requiring only knowledge of the atomic coordinates, is efficient and applicable to large systems, such as proteins or DNA. Across these applications, a view of non-bonded interactions emerges as continuous surfaces rather than close contacts between atom pairs, offering rich insight into the design of new and improved ligands. PMID:20394428

  3. Revealing hidden genuine tripartite nonlocality

    NASA Astrophysics Data System (ADS)

    Paul, Biswajit; Mukherjee, Kaushiki; Sarkar, Debasis

    2016-11-01

    Nonlocal correlations arising from measurements on tripartite entangled states can be classified into two groups, one genuinely three-way nonlocal and other local with respect to some bipartition. Still, whether a genuinely tripartite entangled quantum state can exhibit genuine three-way nonlocality remains a challenging problem as far as measurement context is concerned. Here we introduce an approach in this regard. We consider three tripartite quantum states, none of which is genuinely three-way nonlocal in a specific Bell scenario (three parties, two measurements per party, two outcomes per measurement), but they can exhibit genuine three-way nonlocality when the initial states are subjected to stochastic local operations and classical communication. So, genuine three-way nonlocality is a resource which can be revealed by using a sequence of measurements.

  4. Revealing ontological commitments by magic.

    PubMed

    Griffiths, Thomas L

    2015-03-01

    Considering the appeal of different magical transformations exposes some systematic asymmetries. For example, it is more interesting to transform a vase into a rose than a rose into a vase. An experiment in which people judged how interesting they found different magic tricks showed that these asymmetries reflect the direction a transformation moves in an ontological hierarchy: transformations in the direction of animacy and intelligence are favored over the opposite. A second and third experiment demonstrated that judgments of the plausibility of machines that perform the same transformations do not show the same asymmetries, but judgments of the interestingness of such machines do. A formal argument relates this sense of interestingness to evidence for an alternative to our current physical theory, with magic tricks being a particularly pure source of such evidence. These results suggest that people's intuitions about magic tricks can reveal the ontological commitments that underlie human cognition.

  5. Plan competitions reveal entrepreneurial talent

    SciTech Connect

    Madison, Alison L.

    2011-05-15

    Monthly economic diversity column for Tri-City Herald business section. Excerpt below: There’s something to be said for gaining valuable real-world experience in a structured, nurturing environment. Take for instance learning to scuba dive in the comfort of my resort pool rather than immediately hanging out with sharks while I figure out little things like oxygen tanks and avoiding underwater panic attacks. Likewise, graduate students are getting some excellent, supportive real-world training through university business plan competitions. These competitions are places where smart minds, new technologies, months of preparation and coaching, and some healthy pre-presentation jitters collide to reveal not only solid new business ideas, but also some promising entrepreneurial talent. In fact, professionals from around our region descend upon college campuses every spring to judge these events, which help to bridge the gap between academics and the real technology and business-driven economy.

  6. Erosion and what it Reveals

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 20 November 2003

    This image is located near the boundary between Syrtis Major and Isidis Planitia. The top of the image shows rough material that has eroded away from the lower portion of the image, revealing an underlying surface that has many small craters. It also reveals an ancient flow lobe that is barely discernable, crossing the southern part of the image (this flow lobe is much easier to see as a smooth region in the context image).

    Image information: VIS instrument. Latitude 16.4, Longitude 77.9 East (282.1 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  7. APEX reveals glowing stellar nurseries

    NASA Astrophysics Data System (ADS)

    2008-11-01

    Illustrating the power of submillimetre-wavelength astronomy, an APEX image reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps that are the birthplaces of new stars. Submillimetre light is the key to revealing some of the coldest material in the Universe, such as these cold, dense clouds. Glowing Stellar Nurseries ESO PR Photo 40/08 Glowing Stellar Nurseries The region, called RCW120, is about 4200 light years from Earth, towards the constellation of Scorpius. A hot, massive star in its centre is emitting huge amounts of ultraviolet radiation, which ionises the surrounding gas, stripping the electrons from hydrogen atoms and producing the characteristic red glow of so-called H-alpha emission. As this ionised region expands into space, the associated shock wave sweeps up a layer of the surrounding cold interstellar gas and cosmic dust. This layer becomes unstable and collapses under its own gravity into dense clumps, forming cold, dense clouds of hydrogen where new stars are born. However, as the clouds are still very cold, with temperatures of around -250˚ Celsius, their faint heat glow can only be seen at submillimetre wavelengths. Submillimetre light is therefore vital in studying the earliest stages of the birth and life of stars. The submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope, located on the 5000 m high plateau of Chajnantor in the Chilean Atacama desert. Thanks to LABOCA's high sensitivity, astronomers were able to detect clumps of cold gas four times fainter than previously possible. Since the brightness of the clumps is a measure of their mass, this also means that astronomers can now study the formation of less massive stars than they could before. The plateau of Chajnantor is also where ESO, together with international partners, is building a next generation submillimetre telescope, ALMA

  8. Hubble Images Reveal Jupiter's Auroras

    NASA Technical Reports Server (NTRS)

    1996-01-01

    These images, taken by the Hubble Space Telescope, reveal changes in Jupiter's auroral emissions and how small auroral spots just outside the emission rings are linked to the planet's volcanic moon, Io. The images represent the most sensitive and sharply-detailed views ever taken of Jovian auroras.

    The top panel pinpoints the effects of emissions from Io, which is about the size of Earth's moon. The black-and-white image on the left, taken in visible light, shows how Io and Jupiter are linked by an invisible electrical current of charged particles called a 'flux tube.' The particles - ejected from Io (the bright spot on Jupiter's right) by volcanic eruptions - flow along Jupiter's magnetic field lines, which thread through Io, to the planet's north and south magnetic poles. This image also shows the belts of clouds surrounding Jupiter as well as the Great Red Spot.

    The black-and-white image on the right, taken in ultraviolet light about 15 minutes later, shows Jupiter's auroral emissions at the north and south poles. Just outside these emissions are the auroral spots. Called 'footprints,' the spots are created when the particles in Io's 'flux tube' reach Jupiter's upper atmosphere and interact with hydrogen gas, making it fluoresce. In this image, Io is not observable because it is faint in the ultraviolet.

    The two ultraviolet images at the bottom of the picture show how the auroral emissions change in brightness and structure as Jupiter rotates. These false-color images also reveal how the magnetic field is offset from Jupiter's spin axis by 10 to 15 degrees. In the right image, the north auroral emission is rising over the left limb; the south auroral oval is beginning to set. The image on the left, obtained on a different date, shows a full view of the north aurora, with a strong emission inside the main auroral oval.

    The images were taken by the telescope's Wide Field and Planetary Camera 2 between May 1994 and September 1995.

    This image and

  9. Chandra Reveals Rich Oxygen Supply

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This striking Chandra X-Ray Observatory image of supernova remnant SNR0103-72.6 reveals a nearly perfect ring about 150 light years in diameter surrounding a cloud of gas enriched in oxygen and shock-heated to millions of degrees Celsius. The ring marks the outer limits of a shock wave produced as material ejected in the supernova explosion collides with the interstellar gas. The size of the ring indicates that we see the supernova remnant as it was about 10,000 years after its progenitor star exploded. Located in the Small Magenellanic Cloud (SMC), SNR 0103-72.6 is about 190,000 light years from Earth. The x-rays take about 190,000 years to reach us from the SMC, so the supernova explosion occurred about 200,000 years ago, as measured on Earth. Scientists have know for years that oxygen and many other elements necessary for life are created in massive stars and dispersed in supernova explosions, but few remnants rich in these elements have been observed. This supernova remnant will hence become an important laboratory for studying how stars forge the elements necessary for life.

  10. Dilated Cardiomyopathy Revealing Cushing Disease

    PubMed Central

    Marchand, Lucien; Segrestin, Bérénice; Lapoirie, Marion; Favrel, Véronique; Dementhon, Julie; Jouanneau, Emmanuel; Raverot, Gérald

    2015-01-01

    Abstract Cardiovascular impairments are frequent in Cushing's syndrome and the hypercortisolism can result in cardiac structural and functional changes that lead in rare cases to dilated cardiomyopathy (DCM). Such cardiac impairment may be reversible in response to a eucortisolaemic state. A 43-year-old man with a medical past of hypertension and history of smoking presented to the emergency department with global heart failure. Coronary angiography showed a significant stenosis of a marginal branch and cardiac MRI revealed a nonischemic DCM. The left ventricular ejection fraction (LVEF) was estimated as 28% to 30%. Clinicobiological features and pituitary imaging pointed toward Cushing's disease and administration of adrenolytic drugs (metyrapone and ketoconazole) was initiated. Despite the normalization of cortisol which had been achieved 2 months later, the patient presented an acute heart failure. A massive mitral regurgitation secondary to posterior papillary muscle rupture was diagnosed as a complication of the occlusion of the marginal branch. After 6 months of optimal pharmacological treatment for systolic heart failure, as well as treatment with inhibitors of steroidogenesis, there was no improvement of LVEF. The percutaneous mitral valve was therefore repaired and a defibrillator implanted. The severity of heart failure contraindicated pituitary surgery and the patient was instead treated by stereotaxic radiotherapy. This is the first case reporting a Cushing's syndrome DCM without improvement of LVEF despite normalization of serum cortisol levels. PMID:26579807

  11. Satellites reveal Antarctic mass imbalance

    NASA Astrophysics Data System (ADS)

    Shepherd, A.

    2004-05-01

    Satellite radar observations have revealed a widespread mass imbalance in western Antarctica and rapid thinning of ice shelves at the Antarctic Peninsula. The former shows grounded ice retreat in a region previously considered unstable to such events, and the latter illuminates an ongoing debate as to the mechanism through which ice shelves have disintegrated over the past decade. Both measurements inform us as to the present state of balance of the cryosphere and its interactions with the southern oceans. Since 1992, the Amundsen Sea sector of the West Antarctic Ice Sheet has lost 39 cubic kilometers of its volume each year due to an imbalance between snow accumulation and ice discharge. A flow disturbance is responsible for removing the majority of that ice from the trunks of the Pine Island, Thwaites and Smith glacier drainage systems, raising global sea level by over 1 mm during the past decade alone. The coincidence of rapid ice thinning at the Amundsen Coast and warm circumpolar deep water intrusion in Pine Island Bay, coupled with a ~ 50 cubic kilometre annual freshening of the Ross Sea Gyre downstream, makes ocean melting an attractive proposition for the origin of the regional disturbance. At the same time, the Larsen Ice Shelf surface has lowered by up to 0.27 m per year, in tandem with a period of atmospheric warming and ice shelf collapse. The lowering cannot be explained by increased summer melt-water production alone, and must reflect a loss of basal ice through melting. Ocean temperature measurements close to the ice shelf barrier support this conclusion, making enhanced basal ice melting a likely factor linking the regional climate warming and the successive disintegration of sections of the Larsen Ice Shelf.

  12. [Cholangitis revealing an intrahepatic Osler's disease].

    PubMed

    Asma, Kochlef; Dalila, Gargouri; Olfa, Bousnina; Malika, Romani; Afef, Kilani; Najet, BelHadg; Jamel, Kharrat; Abdeljabbar, Gorbel; Sarra, Shili; Chiraz, Jemli; Mohamed, Habib Daghfous; Slim, Khlifi; Anis, Ben Maamer; Abdelmajid, Letaïef

    2005-08-01

    Osler Weber Rendu Disease is an hereditary haemorrhagic télangectasia habitually revealed by reccurent bleeding (epistaxis). Hepatic involvement in Osler disease is found in 8 to 31%, manifested by cholestasis. We report an original observation of a cholangitis revealing Osler disease.

  13. REVEAL: Software Documentation and Platform Migration

    NASA Technical Reports Server (NTRS)

    Wilson, Michael A.; Veibell, Victoir T.; Freudinger, Lawrence C.

    2008-01-01

    The Research Environment for Vehicle Embedded Analysis on Linux (REVEAL) is reconfigurable data acquisition software designed for network-distributed test and measurement applications. In development since 2001, it has been successfully demonstrated in support of a number of actual missions within NASA s Suborbital Science Program. Improvements to software configuration control were needed to properly support both an ongoing transition to operational status and continued evolution of REVEAL capabilities. For this reason the project described in this report targets REVEAL software source documentation and deployment of the software on a small set of hardware platforms different from what is currently used in the baseline system implementation. This report specifically describes the actions taken over a ten week period by two undergraduate student interns and serves as a final report for that internship. The topics discussed include: the documentation of REVEAL source code; the migration of REVEAL to other platforms; and an end-to-end field test that successfully validates the efforts.

  14. Effects of graphene on electro-optic switching and spontaneous polarization of a ferroelectric liquid crystal

    SciTech Connect

    Basu, Rajratan

    2014-09-15

    A small quantity of graphene flakes was doped in a ferroelectric liquid crystal (FLC), and the field-induced ferroelectric electro-optic switching was found to be significantly faster in the FLC + graphene hybrid than that of the pure FLC. Further studies revealed that the suspended graphene flakes enhanced the FLC's spontaneous polarization by improving smectic-C ordering resulting from the π–π electron stacking, and reduced rotation viscosity by trapping some of the free ions of the FLC media. These effects coherently impacted the FLC-switching phenomenon, enabling the FLC molecules to switch faster on reversing an external electric field.

  15. Transitions between paraelectric and ferroelectric phases of bent-core smectic liquid crystals in the bulk and in thin freely suspended films

    NASA Astrophysics Data System (ADS)

    Eremin, Alexey; Floegel, Martin; Kornek, Ulrike; Stern, Stephan; Stannarius, Ralf; Nádasi, Hajnalka; Weissflog, Wolfgang; Zhu, Chenhui; Shen, Yongqiang; Park, Cheol Soo; Maclennan, Joseph; Clark, Noel

    2012-11-01

    We report on the contrasting phase behavior of a bent-core liquid crystal with a large opening angle between the mesogenic units in the bulk and in freely suspended films. Second-harmonic generation experiments and direct observation of director inversion walls in films in an applied electric field reveal that the nonpolar smectic C phase observed in bulk samples becomes a ferroelectric “banana” phase in films, showing that a mesogen with a small steric moment can give a phase with polar order in freely suspended films even when the corresponding bulk phase is paraelectric.

  16. Hiding personal information reveals the worst

    PubMed Central

    John, Leslie K.; Barasz, Kate; Norton, Michael I.

    2016-01-01

    Seven experiments explore people’s decisions to share or withhold personal information, and the wisdom of such decisions. When people choose not to reveal information—to be “hiders”—they are judged negatively by others (experiment 1). These negative judgments emerge when hiding is volitional (experiments 2A and 2B) and are driven by decreases in trustworthiness engendered by decisions to hide (experiments 3A and 3B). Moreover, hiders do not intuit these negative consequences: given the choice to withhold or reveal unsavory information, people often choose to withhold, but observers rate those who reveal even questionable behavior more positively (experiments 4A and 4B). The negative impact of hiding holds whether opting not to disclose unflattering (drug use, poor grades, and sexually transmitted diseases) or flattering (blood donations) information, and across decisions ranging from whom to date to whom to hire. When faced with decisions about disclosure, decision-makers should be aware not just of the risk of revealing, but of what hiding reveals. PMID:26755591

  17. REVEAL: Software Documentation and Platform Migration

    NASA Technical Reports Server (NTRS)

    Wilson, Michael A.; Veibell, Victoir T.

    2011-01-01

    The Research Environment for Vehicle Embedded Analysis on Linux (REVEAL) is reconfigurable data acquisition software designed for network-distributed test and measurement applications. In development since 2001, it has been successfully demonstrated in support of a number of actual missions within NASA's Suborbital Science Program. Improvements to software configuration control were needed to properly support both an ongoing transition to operational status and continued evolution of REVEAL capabilities. For this reason the project described in this report targets REVEAL software source documentation and deployment of the software on a small set of hardware platforms different from what is currently used in the baseline system implementation. This presentation specifically describes the actions taken over a ten week period by two undergraduate student interns and serves as an overview of the content of the final report for that internship.

  18. Comparing SessionStateReveal and EphemeralKeyReveal for Diffie-Hellman Protocols

    NASA Astrophysics Data System (ADS)

    Ustaoglu, Berkant

    Both the "eCK" model, by LaMacchia, Lauter and Mityagin, and the "CK01" model, by Canetti and Krawczyk, address the effect of leaking session specific ephemeral data on the security of key establishment schemes. The CK01-adversary is given a SessionStateReveal query to learn session-specific private data defined by the protocol specification, whereas the eCK-adversary is equipped with an EphemeralKeyReveal query to access all ephemeral private input required to carry session computations. SessionStateReveal cannot be issued against the test session; by contrast EphemeralKeyReveal can be used against the test session under certain conditions. On the other hand, it is not obvious how EphemeralKeyReveal compares to SessionStateReveal. Thus it is natural to ask which model is more useful and practically relevant.

  19. Open chromatin reveals the functional maize genome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Every cellular process mediated through nuclear DNA must contend with chromatin. As results from ENCODE show, open chromatin assays can efficiently integrate across diverse regulatory elements, revealing functional non-coding genome. In this study, we use a MNase hypersensitivity assay to discover o...

  20. Revealing a Child's Pathology: Physicians' Experiences

    ERIC Educational Resources Information Center

    Scelles, Regine; Aubert-Godard, Anne; Gargiulo, Marcela; Avant, Monique; Gortais, Jean

    2010-01-01

    In this study, 12 physicians and 12 care-givers were interviewed using semi-structured interviews. We explored physicians' experiences when they revealed a diagnosis. We also tried to understand which family members the physician was thinking of, with whom they identified themselves, and their first choice of the person to whom they prefer to…

  1. Revealing Student Teacher's Thinking through Dilemma Analysis

    ERIC Educational Resources Information Center

    Talanquer, Vicente; Tomanek, Debra; Novodvorsky, Ingrid

    2007-01-01

    We explore the potential of dilemma analysis as an assessment tool to reveal student teachers' thinking and concerns about their practice. For this purpose we analyze the dilemma analyses completed by 22 student teachers enrolled in our science teacher preparation program over a period of four semesters. Student teachers' dilemmas fall into two…

  2. Eye Movements Reveal Dynamics of Task Control

    ERIC Educational Resources Information Center

    Mayr, Ulrich; Kuhns, David; Rieter, Miranda

    2013-01-01

    With the goal to determine the cognitive architecture that underlies flexible changes of control settings, we assessed within-trial and across-trial dynamics of attentional selection by tracking of eye movements in the context of a cued task-switching paradigm. Within-trial dynamics revealed a switch-induced, discrete delay in onset of…

  3. Revealing Student Teachers' Thinking through Dilemma Analysis

    NASA Astrophysics Data System (ADS)

    Talanquer, Vicente; Tomanek, Debra; Novodvorsky, Ingrid

    2007-06-01

    We explore the potential of dilemma analysis as an assessment tool to reveal student teachers’ thinking and concerns about their practice. For this purpose we analyze the dilemma analyses completed by 22 student teachers enrolled in our science teacher preparation program over a period of four semesters. Student teachers’ dilemmas fall into two main groups: dilemmas about student performance and dilemmas associated with instructional decisions. These dilemmas reveal a variety of concerns that student teachers have about their work. In particular, concerns about lack of student motivation and its consequences on performance and instruction play a central role in student teachers’ thinking. The recognition of common patterns of thought in our student teacher thinking has made us reflect on and re-evaluate important components of the curriculum in our science teacher preparation program.

  4. [Pseudotumoral toxoplasmic cystitis revealing acquired immunodeficiency syndrome].

    PubMed

    Ples, Raluca; Méchaï, Frédéric; Champiat, Bernard; Droupy, Stéphane; Huerre, Michel; Guettier, Catherine; Ferlicot, Sophie

    2011-02-01

    A case of bladder toxoplasmosis in a 57-year-old male Caucasian patient was diagnosed with difficulty due to misleading clinical presentation. The patient presented with pollakiuria and urination burning. Imagery showed pseudotumoral thickening of the vesicle wall. Previously unknown status of HIV infection was found positive through the diagnosis of bladder toxoplasmosis. The patient died rapidly from neurological complications. This is the second published case in which bladder toxoplasmosis reveals an HIV infection.

  5. Experts reveal catalyst-selection methodologies

    SciTech Connect

    1996-10-14

    Refining catalyst selection procedure were discussed in detail at Oil and Gas Journal`s International Catalyst Conference, Feb. 1--2, in Houston. Marathon Oil Co.`s James P. Wick revealed details of Marathon`s program for review and optimization of fluid catalytic cracking (FCC) and hydrotreating catalysts. And renowned FCC expert Del Tolen outlined a step-by-step procedure for choosing an FCC catalyst. The paper describes Marathon`s program and Tolen`s selection process.

  6. Satellite altimetry reveals seafloor tectonic fabric

    SciTech Connect

    Mcadoo, D.C.; Marks, K.M. )

    1992-01-01

    Seasat altimeter observations of sea-surface topography have revealed much that was unsuspected about the marine gravity field and seafloor topography, which in conjunction with crustal/upper-mantle density variations generates short wavelength (less than 200-km) marine gravity field fluctuations. Such high-resolution altimeter data is currently available, however, only for 6 percent of the world's ocean surface area; future efforts with Geosat Geodetic Mission and ERS-1 data will expand coverage to the entire world ocean. 4 refs.

  7. Apocalypto: revealing lost text with XMT

    NASA Astrophysics Data System (ADS)

    Mills, David; Davis, Graham R.; Lai, Yu-kun; Rosin, Paul

    2014-09-01

    "Can brute-force high-contrast tomography techniques and image processing techniques retrieve textual content from damaged heritage materials?" The Dental Institute at Queen Mary University of London (QMUL) is the leading centre for very high contrast X-Ray Microtomography imaging. The Apocalypto Project is our collaboration with the heritage community and experts in Computer Vision systems in the Computer Science Department at Cardiff University. This collaboration has developed techniques and a workflow that allows us to reveal textual content from moisture-damaged parchment rolls. This article will also present some initial results from burned and heat shrunken parchment rolls, an insect damaged Mamluk cap and a birch bark roll.

  8. Trench Reveals Two Faces of Soils

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This approximate true-color image mosaic from the panoramic camera on the Mars Exploration Rover Opportunity shows a trench dug by the rover in the vicinity of the 'Anatolia' region. Two imprints from the rover's Mossbauer spectrometer instrument were left in the exposed soils. Detailed comparisons between soils exposed at the surface and those found at depth reveal that surface soils have higher levels of hematite while subsurface soils show fine particles derived from basalt. The trench is approximately 11 centimeters deep. This image was taken on sol 81 with the panoramic camera's 430-, 530- and 750-nanometer filters.

  9. Infections Revealing Complement Deficiency in Adults

    PubMed Central

    Audemard-Verger, A.; Descloux, E.; Ponard, D.; Deroux, A.; Fantin, B.; Fieschi, C.; John, M.; Bouldouyre, A.; Karkowsi, L.; Moulis, G.; Auvinet, H.; Valla, F.; Lechiche, C.; Davido, B.; Martinot, M.; Biron, C.; Lucht, F.; Asseray, N.; Froissart, A.; Buzelé, R.; Perlat, A.; Boutboul, D.; Fremeaux-Bacchi, V.; Isnard, S.; Bienvenu, B.

    2016-01-01

    Abstract Complement system is a part of innate immunity, its main function is to protect human from bacterial infection. As genetic disorders, complement deficiencies are often diagnosed in pediatric population. However, complement deficiencies can also be revealed in adults but have been poorly investigated. Herein, we describe a case series of infections revealing complement deficiency in adults to study clinical spectrum and management of complement deficiencies. A nationwide retrospective study was conducted in French university and general hospitals in departments of internal medicine, infectious diseases enrolling patients older than 15 years old who had presented at least one infection leading to a complement deficiency diagnosis. Forty-one patients included between 2002 and 2015 in 19 different departments were enrolled in this study. The male-to-female ratio was 1.3 and the mean age at diagnosis was 28 ± 14 (15–67) years. The main clinical feature was Neisseria meningitidis meningitis 75% (n = 31/41) often involving rare serotype: Y (n = 9) and W 135 (n = 7). The main complement deficiency observed was the common final pathway deficiency 83% (n = 34/41). Half of the cohort displayed severe sepsis or septic shock at diagnosis (n = 22/41) but no patient died. No patient had family history of complement deficiency. The mean follow-up was 1.15 ± 1.95 (0.1–10) years. Half of the patients had already suffered from at least one infection before diagnosis of complement deficiency: meningitis (n = 13), pneumonia (n = 4), fulminans purpura (n = 1), or recurrent otitis (n = 1). Near one-third (n = 10/39) had received prophylactic antibiotics (cotrimoxazole or penicillin) after diagnosis of complement deficiency. The vaccination coverage rate, at the end of the follow-up, for N meningitidis, Streptococcus pneumonia, and Haemophilius influenzae were, respectively, 90% (n = 33/37), 47% (n = 17/36), and 35

  10. Symbiotic conversations are revealed under genetic interrogation

    PubMed Central

    Ruby, Edward G.

    2013-01-01

    The recent development and application of molecular genetics to the symbionts of invertebrate animal species have advanced our knowledge of the biochemical communication that occurs between the host and its bacterial symbionts. In particular, the ability to manipulate these associations experimentally by introducing genetic variants of the symbionts into naive hosts has allowed the discovery of novel colonization mechanisms and factors. In addition, the role of the symbionts in inducing normal host development has been revealed, and its molecular basis described. In this Review, I discuss many of these developments, focusing on what has been discovered in five well-understood model systems. PMID:18794913

  11. Effect of Enantiomeric Excess on the Phase Behavior of Antiferroelectric Liquid Crystals

    SciTech Connect

    L Pan; B McCoy; S Wang; Z Liu; S Wang; R Pindak; C Huang

    2011-12-31

    Null transmission ellipsometry and resonant x-ray diffraction are employed to study the effect of enantiomeric excess (EE) on the phase behavior of antiferroelectric liquid crystal 10OTBBB1M7. Phase sequence, layer spacing, and pitch of the helical structures of the smectic-C*{sub {alpha}} and smectic-C* phases are studied as a function of temperature and EE. Upon reducing EE, a liquid-gas-type critical point of the smectic-C*{sub {alpha}} to smectic-C* transition is observed, as well as the disappearance of the smectic-C*{sub d4} and the smectic-C*{sub d3} phases. Results are analyzed in a mean-field model.

  12. Interior Evolution of Ceres Revealed by Dawn

    NASA Astrophysics Data System (ADS)

    Raymond, Carol A.; Park, Ryan S.; Konopliv, Alex S.; Bland, Michael T.; Marchi, Simone; Castillo-Rogez, Julie C.; McCord, Thomas B.; Jaumann, Ralf; Russell, Christopher T.; Prettyman, Thomas H.

    2015-11-01

    Dawn's exploration of Ceres has revealed its geophysical characteristics, informing the processes that have shaped it. Dawn has determined the average diameter of Ceres to be 940 km, smaller than the previously estimated 975 km [1]. This implies a density of 2160 kg/m3, indicating that Ceres is less differentiated than predicted [2]. The low-degree gravity field is consistent with the body being in hydrostatic equilibrium and the magnitude of J2 implies some central condensation. Ceres' entire surface is cratered, implying the lack of a thick (10's of km) water ice layer at the surface. Variability in Ceres' crater morphology indicates that the near-surface layer has variable strength and rheology, likely due to heterogeneity in the near-surface mixture of rock, ice and salt. The lack of a number of expected large impact basins on Ceres can be interpreted to be the result of viscous relaxation, resurfacing or a combination of both. These data provide insights into Ceres' thermal evolution and mechanical properties, which appear to be unique to this warm, icy body.[1] Thomas, P. C., et al., Differentiation of the asteroid Ceres as revealed by its shape, Nature, 437, 224-226, 2005; [2] McCord et al., Ceres: Its Origin, Evolution and Structure and Dawn's Potential Contribution, Space Sci Rev DOI 10.1007/s11214-010-9729-9, 2011.

  13. Revealing Event Saliency in Unconstrained Video Collection.

    PubMed

    Zhang, Dingwen; Han, Junwei; Jiang, Lu; Ye, Senmao; Chang, Xiaojun

    2017-04-01

    Recent progresses in multimedia event detection have enabled us to find videos about a predefined event from a large-scale video collection. Research towards more intrinsic unsupervised video understanding is an interesting but understudied field. Specifically, given a collection of videos sharing a common event of interest, the goal is to discover the salient fragments, i.e., the curt video fragments that can concisely portray the underlying event of interest, from each video. To explore this novel direction, this paper proposes an unsupervised event saliency revealing framework. It first extracts features from multiple modalities to represent each shot in the given video collection. Then, these shots are clustered to build the cluster-level event saliency revealing framework, which explores useful information cues (i.e., the intra-cluster prior, inter-cluster discriminability, and inter-cluster smoothness) by a concise optimization model. Compared with the existing methods, our approach could highlight the intrinsic stimulus of the unseen event within a video in an unsupervised fashion. Thus, it could potentially benefit to a wide range of multimedia tasks like video browsing, understanding, and search. To quantitatively verify the proposed method, we systematically compare the method to a number of baseline methods on the TRECVID benchmarks. Experimental results have demonstrated its effectiveness and efficiency.

  14. Metabolomics reveals metabolic biomarkers of Crohn's disease

    SciTech Connect

    Jansson, J.K.; Willing, B.; Lucio, M.; Fekete, A.; Dicksved, J.; Halfvarson, J.; Tysk, C.; Schmitt-Kopplin, P.

    2009-06-01

    The causes and etiology of Crohn's disease (CD) are currently unknown although both host genetics and environmental factors play a role. Here we used non-targeted metabolic profiling to determine the contribution of metabolites produced by the gut microbiota towards disease status of the host. Ion Cyclotron Resonance Fourier Transform Mass Spectrometry (ICR-FT/MS) was used to discern the masses of thousands of metabolites in fecal samples collected from 17 identical twin pairs, including healthy individuals and those with CD. Pathways with differentiating metabolites included those involved in the metabolism and or synthesis of amino acids, fatty acids, bile acids and arachidonic acid. Several metabolites were positively or negatively correlated to the disease phenotype and to specific microbes previously characterized in the same samples. Our data reveal novel differentiating metabolites for CD that may provide diagnostic biomarkers and/or monitoring tools as well as insight into potential targets for disease therapy and prevention.

  15. Sawfishes stealth revealed using computational fluid dynamics.

    PubMed

    Bradney, D R; Davidson, A; Evans, S P; Wueringer, B E; Morgan, D L; Clausen, P D

    2017-02-27

    Detailed computational fluid dynamics simulations for the rostrum of three species of sawfish (Pristidae) revealed that negligible turbulent flow is generated from all rostra during lateral swipe prey manipulation and swimming. These results suggest that sawfishes are effective stealth hunters that may not be detected by their teleost prey's lateral line sensory system during pursuits. Moreover, during lateral swipes, the rostra were found to induce little velocity into the surrounding fluid. Consistent with previous data of sawfish feeding behaviour, these data indicate that the rostrum is therefore unlikely to be used to stir up the bottom to uncover benthic prey. Whilst swimming with the rostrum inclined at a small angle to the horizontal, the coefficient of drag of the rostrum is relatively low and the coefficient of lift is zero.

  16. Neutron Imaging Reveals Internal Plant Hydraulic Dynamics

    SciTech Connect

    Warren, Jeffrey; Bilheux, Hassina Z; Kang, Misun; Voisin, Sophie; Cheng, Chu-Lin; Horita, Jusuke; Perfect, Edmund

    2013-01-01

    Many terrestrial ecosystem processes are constrained by water availability and transport within the soil. Knowledge of plant water fluxes is thus critical for assessing mechanistic processes linked to biogeochemical cycles, yet resolution of root structure and xylem water transport dynamics has been a particularly daunting task for the ecologist. Through neutron imaging, we demonstrate the ability to non-invasively monitor individual root functionality and water fluxes within Zea mays L. (maize) and Panicum virgatum L. (switchgrass) seedlings growing in a sandy medium. Root structure and growth were readily imaged by neutron radiography and neutron computed tomography. Seedlings were irrigated with water or deuterium oxide and imaged through time as a growth lamp was cycled on to alter leaf demand for water. Sub-millimeter scale resolution reveals timing and magnitudes of root water uptake, redistribution within the roots, and root-shoot hydraulic linkages, relationships not well characterized by other techniques.

  17. Paraventricular meningioma revealed by mental disorder

    PubMed Central

    Hilmani, Said; Houass, Yassine; El Azhari, Abdessamad

    2016-01-01

    Background: Ventricular meningioma constitutes 2% of intracranial meningioma, representing a challenging disease for neurosurgeons. Although cognitive impairment is one of the major symptoms of ventricular tumors, few studies have reported the details of cognitive impairment before and after their surgical removal. The expected effects on cognitive function should also be considered when choosing a surgical approach. Case Descriptions: We report the case of a large lateral ventricle meningioma revealed by cognitive dysfunction and moderate intellectual disability. The patient underwent subtotal resection of the tumor which had partial improvement in cognitive disorders. It is important to precisely assess neuropsychological function in patients with large brain tumors, and judicious preoperative plan, adequate knowledge of anatomy, and use of correct microsurgical techniques are fundamental in achieving complete resection of paraventricular meningioma with low morbidity. Conclusion: Pre and postoperative precise neuropsychological examinations may identify the potential cognitive impairment and beneficial effects of surgery in patients with large lateral ventricle meningiomas. PMID:28144473

  18. Memory strength and specificity revealed by pupillometry.

    PubMed

    Papesh, Megan H; Goldinger, Stephen D; Hout, Michael C

    2012-01-01

    Voice-specificity effects in recognition memory were investigated using both behavioral data and pupillometry. Volunteers initially heard spoken words and nonwords in two voices; they later provided confidence-based old/new classifications to items presented in their original voices, changed (but familiar) voices, or entirely new voices. Recognition was more accurate for old-voice items, replicating prior research. Pupillometry was used to gauge cognitive demand during both encoding and testing: enlarged pupils revealed that participants devoted greater effort to encoding items that were subsequently recognized. Further, pupil responses were sensitive to the cue match between encoding and retrieval voices, as well as memory strength. Strong memories, and those with the closest encoding-retrieval voice matches, resulted in the highest peak pupil diameters. The results are discussed with respect to episodic memory models and Whittlesea's (1997) SCAPE framework for recognition memory.

  19. Fracture reveals clustering in cohesive granular matter

    NASA Astrophysics Data System (ADS)

    Tapia, Franco; Santucci, Stéphane; Géminard, Jean-Christophe

    2016-09-01

    We report an experimental study of the morphology of fractures in cohesive granular materials. Cohesion is introduced by equilibrating the grains with a humid atmosphere. The setup allows to produce a controlled crack in a thin layer of a glass beads assembly, and observe with an extremely high resolution the edge of the fracture at the free surface of the layer. The detailed multi-scale analysis of the fracture profile reveals the presence, in the bulk of the material, of clusters of grains whose size increases monotonically with the relative humidity. These results are important because the formation of clusters, resulting in a heterogeneity of the cohesion force, governs the mechanical properties of cohesive granular matter in contact with a humid atmosphere.

  20. Social patterns revealed through random matrix theory

    NASA Astrophysics Data System (ADS)

    Sarkar, Camellia; Jalan, Sarika

    2014-11-01

    Despite the tremendous advancements in the field of network theory, very few studies have taken weights in the interactions into consideration that emerge naturally in all real-world systems. Using random matrix analysis of a weighted social network, we demonstrate the profound impact of weights in interactions on emerging structural properties. The analysis reveals that randomness existing in particular time frame affects the decisions of individuals rendering them more freedom of choice in situations of financial security. While the structural organization of networks remains the same throughout all datasets, random matrix theory provides insight into the interaction pattern of individuals of the society in situations of crisis. It has also been contemplated that individual accountability in terms of weighted interactions remains as a key to success unless segregation of tasks comes into play.

  1. Revealing effective classifiers through network comparison

    NASA Astrophysics Data System (ADS)

    Gallos, Lazaros K.; Fefferman, Nina H.

    2014-11-01

    The ability to compare complex systems can provide new insight into the fundamental nature of the processes captured, in ways that are otherwise inaccessible to observation. Here, we introduce the n-tangle method to directly compare two networks for structural similarity, based on the distribution of edge density in network subgraphs. We demonstrate that this method can efficiently introduce comparative analysis into network science and opens the road for many new applications. For example, we show how the construction of a “phylogenetic tree” across animal taxa according to their social structure can reveal commonalities in the behavioral ecology of the populations, or how students create similar networks according to the University size. Our method can be expanded to study many additional properties, such as network classification, changes during time evolution, convergence of growth models, and detection of structural changes during damage.

  2. Open chromatin reveals the functional maize genome

    PubMed Central

    Rodgers-Melnick, Eli; Vera, Daniel L.; Bass, Hank W.

    2016-01-01

    Cellular processes mediated through nuclear DNA must contend with chromatin. Chromatin structural assays can efficiently integrate information across diverse regulatory elements, revealing the functional noncoding genome. In this study, we use a differential nuclease sensitivity assay based on micrococcal nuclease (MNase) digestion to discover open chromatin regions in the maize genome. We find that maize MNase-hypersensitive (MNase HS) regions localize around active genes and within recombination hotspots, focusing biased gene conversion at their flanks. Although MNase HS regions map to less than 1% of the genome, they consistently explain a remarkably large amount (∼40%) of heritable phenotypic variance in diverse complex traits. MNase HS regions are therefore on par with coding sequences as annotations that demarcate the functional parts of the maize genome. These results imply that less than 3% of the maize genome (coding and MNase HS regions) may give rise to the overwhelming majority of phenotypic variation, greatly narrowing the scope of the functional genome. PMID:27185945

  3. Ceres Revealed in a Grain of Salt

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Bodnar, R. J.; Fries, M.; Chan, Q. H.-S.; Kebukawa, Y.; Mikouchi, T.; Hagiya, K.; Komatsu, M.; Ohsumi, K.; Steele, A.

    2016-01-01

    Introduction: Zag and Monahans (1998) are H chondrite regolith breccias containing 4.5 giga-year-old halite crystals which contain abundant inclusions of aqueous fluids, solids and organics. These all originated on a cryo-volcanically-active C class asteroid, probably 1 Ceres; the halite was transported to the regolith of the H chondrite parent asteroid, potentially 6 Hebe. Detailed analysis of these solids will thus potentially reveal the mineralogy of Ceres. Mineralogy of solids in the Monahans Halite Solid grains are present in the halites, which were entrained within the mother brines during eruption, including material from the interior and surface of the erupting body. The solids include abundant, widely variable organics that could not have been significantly heated (which would have resulted in the loss of fluids from the halite). Our analyses by Raman microprobe, SEM/EDX, synchrotron X-ray diffraction, UPLC-FD/QToF-MS, C-XANES and TEM reveal that these trapped grains include macromolecular carbon (MMC) similar in structure to CV3 chondrite matrix carbon, aliphatic carbon compounds, olivine (Fo99-59), high- and low-Ca pyroxene, feldspars, phyllosilicates, magnetite, sulfides, metal, lepidocrocite, carbonates, diamond, apatite and zeolites. Conclusions: The halite in Monahans and Zag derive from a water and carbon-rich object that was cryo-volcanically active in the early solar system, probably Ceres. The Dawn spacecraft found that Ceres includes C chondrite materials. Our samples include both protolith and aqueously-altered samples of the body, permitting understanding of alteration conditions. Whatever the halite parent body, it was rich in a wide variety of organics and warm, liquid water at the solar system's dawn.

  4. Neutron Imaging Reveals Internal Plant Hydraulic Dynamics

    NASA Astrophysics Data System (ADS)

    Warren, J.; Bilheux, H.; Kang, M.; Voisin, S.; Cheng, C.; Horita, J.; Perfect, E.

    2011-12-01

    In situ quantification of soil-plant water fluxes have not been fully successful due to a lack of non-destructive techniques capable of revealing roots or water fluxes at relevant spatial scales. Neutron imaging is a unique non-invasive tool that can assess sub-millimeter scale material properties and transport in situ, and which has been successfully applied to characterize soil and plant water status. Here, we have applied neutron radiography and tomography to quantify water transport through individual maize roots in response to internal plant demand. Zea mays seedlings were grown for 10 days in Flint silica sand within 2.6 cm diameter Al chambers. Using a reactor-based neutron source at Oak Ridge National Laboratory (HFIR), water fluxes were tracked through the maize soil-root systems by collecting consecutive neutron radiographs over a 12 h period following irrigation with D2O. D has a much lower neutron attenuation than H, thus D2O displacement of existing H2O within the plant vascular system, or influx of D2O into previously dry tissue or soil is readily tracked by changes in image intensity through time. Plant water release and uptake was regulated by periodically cycling on a high-intensity grow light. From each maize replicate, selected regions of interest (ROI) were delineated around individual roots, root free soil, stem and leaf segments. Changes in ROI were tracked through time to reveal patterns of water flux. The hydration of root and stem tissue cycled in response to illumination; root water content often increased during darkness, then decreased with illumination as water was transported from the root into the stem. Relative root-shoot hydration through time illustrates the balance between demand, storage capacity and uptake, which varies depending on root characteristics and its localized soil environment. The dynamic transport of water between soil, individual roots, stems and leaves was readily visualized and quantified illustrating the value

  5. Elasticity of smectic liquid crystals with in-plane orientational order and dispiration asymmetry

    NASA Astrophysics Data System (ADS)

    Alageshan, Jaya Kumar; Chakrabarti, Buddhapriya; Hatwalne, Yashodhan

    2017-02-01

    The Nelson-Peliti formulation of the elasticity theory of isolated fluid membranes with orientational order emphasizes the interplay between geometry, topology, and thermal fluctuations. Fluid layers of lamellar liquid crystals such as smectic-C , hexatic smectics, and smectic-C* are endowed with in-plane orientational order. We extend the Nelson-Peliti formulation so as to bring these smectics within its ambit. Using the elasticity theory of smectics-C*, we show that positive and negative dispirations (topological defects in Smectic-C* liquid crystals) with strengths of equal magnitude have disparate energies—a result that is amenable to experimental tests.

  6. VISTA Reveals the Secret of the Unicorn

    NASA Astrophysics Data System (ADS)

    2010-10-01

    A new infrared image from ESO's VISTA survey telescope reveals an extraordinary landscape of glowing tendrils of gas, dark clouds and young stars within the constellation of Monoceros (the Unicorn). This star-forming region, known as Monoceros R2, is embedded within a huge dark cloud. The region is almost completely obscured by interstellar dust when viewed in visible light, but is spectacular in the infrared. An active stellar nursery lies hidden inside a massive dark cloud rich in molecules and dust in the constellation of Monoceros. Although it appears close in the sky to the more familiar Orion Nebula it is actually almost twice as far from Earth, at a distance of about 2700 light-years. In visible light a grouping of massive hot stars creates a beautiful collection of reflection nebulae where the bluish starlight is scattered from parts of the dark, foggy outer layers of the molecular cloud. However, most of the new-born massive stars remain hidden as the thick interstellar dust strongly absorbs their ultraviolet and visible light. In this gorgeous infrared image taken from ESO's Paranal Observatory in northern Chile, the Visible and Infrared Survey Telescope for Astronomy (VISTA [1], eso0949) penetrates the dark curtain of cosmic dust and reveals in astonishing detail the folds, loops and filaments sculpted from the dusty interstellar matter by intense particle winds and the radiation emitted by hot young stars. "When I first saw this image I just said 'Wow!' I was amazed to see all the dust streamers so clearly around the Monoceros R2 cluster, as well as the jets from highly embedded young stellar objects. There is such a great wealth of exciting detail revealed in these VISTA images," says Jim Emerson, of Queen Mary, University of London and leader of the VISTA consortium. With its huge field of view, large mirror and sensitive camera, VISTA is ideal for obtaining deep, high quality infrared images of large areas of the sky, such as the Monoceros R2 region

  7. Revealing Invisible Photonic Inscriptions: Images from Strain

    PubMed Central

    2015-01-01

    Photonic structural materials have received intensive interest and have been strongly developed over the past few years for image displays, sensing, and anticounterfeit materials. Their “smartness” arises from their color responsivity to changes of environment, strain, or external fields. Here, we introduce a novel invisible photonic system that reveals encrypted images or characters by simply stretching, or immersing in solvents. This type of intriguing photonic material is composed of regularly arranged core–shell particles that are selectively cross-linked by UV irradiation, giving different strain response compared to un-cross-linked regions. The images reversibly appear and disappear when cycling the strain and releasing it. The unique advantages of this soft polymer opal system compared with other types of photonic gels are that it can be produced in roll to roll quantities, can be vigorously deformed to achieve strong color changes, and has no solvent evaporation issues because it is a photonic rubber system. We demonstrate potential applications together with a fabrication procedure which is straightforward and scalable, vital for user take-up. Our work deepens understanding of this rubbery photonic system based on core–shell nanospheres. PMID:26039279

  8. Overnight lexical consolidation revealed by speech segmentation.

    PubMed

    Dumay, Nicolas; Gareth Gaskell, M

    2012-04-01

    Two experiments explored the consolidation of spoken words, and assessed whether post-sleep novel competitor effects truly reflect engagement of these novel words in competition for lexical segmentation. Two types of competitor relationships were contrasted: the onset-aligned case (such as "frenzylk"), where the novel word is a close variant of the existing word: they start at the same time point and overlap on most of their segments; and the fully embedding case (such as "lirmucktoze"), where the existing word corresponds to a smaller embedded portion of its novel competitor and is thus less noticeable. Experiment 1 (pause detection) revealed a similar performance for both cases, with no competitor effect immediately after exposure, but significant inhibition after 24 h and seven days. Experiment 2 (word spotting) produced exactly the same pattern; however, as is the case with existing word carriers (cf. McQueen, Norris, & Cutler, 1994), the inhibition was much stronger for fully embedded than for onset-aligned targets (e.g., "lirmuckt" vs. "frenzyl"). Meanwhile, explicit measures of learning, i.e., free recall and recognition, improved over time. These results cannot be explained by either consolidation of episodic traces or acquisition of new phonological/dialectal variants. We argue instead that they reflect a general trait of vocabulary learning and consolidation.

  9. Revealing Open Quantum Systems with Subsystem DFT

    NASA Astrophysics Data System (ADS)

    Krishtal, Alisa; Pavanello, Michele

    The traditional quantum chemical methods, wave function or density based, are designed to solve for a closed system, where the Hamiltonian contains all relevant interactions. The closed system is, however, not realistic, as in real life the system is embedded in an environment with which it interacts to some degree. Including the description of the environment at the full quantum mechanical level leads to the Open Quantum Systems (OQS) theory: the only theory which can describe non-Markovian dynamics between the system and the environment. By allowing the flow of information in both directions phenomena such as quantum entanglement, relevant for the design of quantum computers, become available. While most OQS theories rely on the density matrix to describe the system-bath interaction, time-dependent subsystem DFT allows to approach the problem using the electron density. Through Dyson-like equations connecting the density-density response kernels of the OQS and its environment, the extent to which non-Markovian dynamics is present can be revealed. We illustrate this for the process of excitation energy transfer in coupled chromophores embedded in explicit solvent.

  10. Sequence tagging reveals unexpected modifications in toxicoproteomics.

    PubMed

    Dasari, Surendra; Chambers, Matthew C; Codreanu, Simona G; Liebler, Daniel C; Collins, Ben C; Pennington, Stephen R; Gallagher, William M; Tabb, David L

    2011-02-18

    Toxicoproteomic samples are rich in posttranslational modifications (PTMs) of proteins. Identifying these modifications via standard database searching can incur significant performance penalties. Here, we describe the latest developments in TagRecon, an algorithm that leverages inferred sequence tags to identify modified peptides in toxicoproteomic data sets. TagRecon identifies known modifications more effectively than the MyriMatch database search engine. TagRecon outperformed state of the art software in recognizing unanticipated modifications from LTQ, Orbitrap, and QTOF data sets. We developed user-friendly software for detecting persistent mass shifts from samples. We follow a three-step strategy for detecting unanticipated PTMs in samples. First, we identify the proteins present in the sample with a standard database search. Next, identified proteins are interrogated for unexpected PTMs with a sequence tag-based search. Finally, additional evidence is gathered for the detected mass shifts with a refinement search. Application of this technology on toxicoproteomic data sets revealed unintended cross-reactions between proteins and sample processing reagents. Twenty-five proteins in rat liver showed signs of oxidative stress when exposed to potentially toxic drugs. These results demonstrate the value of mining toxicoproteomic data sets for modifications.

  11. Phylogenetic proximity revealed by neurodevelopmental event timings.

    PubMed

    Nagarajan, Radhakrishnan; Clancy, Barbara

    2008-01-01

    Statistical properties such as distribution and correlation signatures were investigated using a temporal database of common neurodevelopmental events in the three species most frequently used in experimental studies, rat, mouse, and macaque. There was a fine nexus between phylogenetic proximity and empirically derived dates of the occurrences of 40 common events including the neurogenesis of cortical layers and outgrowth milestones of developing axonal projections. Exponential and power-law approximations to the distribution of the events reveal strikingly similar decay patterns in rats and mice when compared to macaques. Subsequent hierarchical clustering of the common event timings also captures phylogenetic proximity, an association further supported by multivariate linear regression data. These preliminary results suggest that statistical analyses of the timing of developmental milestones may offer a novel measure of phylogenetic classifications. This may have added pragmatic value in the specific support it offers for the reliability of rat/mouse comparative modeling, as well as in the broader implications for the potential of meta-analyses using databases assembled from the extensive empirical literature.

  12. Revealing global regulatory perturbations across human cancers

    PubMed Central

    Goodarzi, Hani; Elemento, Olivier; Tavazoie, Saeed

    2010-01-01

    Summary The discovery of pathways and regulatory networks whose perturbation contributes to neoplastic transformation remains a fundamental challenge for cancer biology. We show that such pathway perturbations, and the cis-regulatory elements through which they operate, can be efficiently extracted from global gene-expression profiles. Our approach utilizes information-theoretic analysis of expression levels, pathways, and genomic sequences. Analysis across a diverse set of human cancers reveals the majority of previously known cancer pathways. Through de novo motif discovery we associate these pathways with transcription-factor binding sites and miRNA targets, including those of E2F, NF-Y, p53, and let-7. Follow-up experiments confirmed that these predictions correspond to functional in vivo regulatory interactions. Strikingly, the majority of the perturbations, associated with putative cis-regulatory elements, fall outside of known cancer pathways. Our study provides a systems-level dissection of regulatory perturbations in cancer—an essential component of a rational strategy for therapeutic intervention and drug-target discovery. PMID:20005852

  13. Revealing the dual streams of speech processing

    PubMed Central

    Fridriksson, Julius; Yourganov, Grigori; Bonilha, Leonardo; Basilakos, Alexandra; Rorden, Christopher

    2016-01-01

    Several dual route models of human speech processing have been proposed suggesting a large-scale anatomical division between cortical regions that support motor–phonological aspects vs. lexical–semantic aspects of speech processing. However, to date, there is no complete agreement on what areas subserve each route or the nature of interactions across these routes that enables human speech processing. Relying on an extensive behavioral and neuroimaging assessment of a large sample of stroke survivors, we used a data-driven approach using principal components analysis of lesion-symptom mapping to identify brain regions crucial for performance on clusters of behavioral tasks without a priori separation into task types. Distinct anatomical boundaries were revealed between a dorsal frontoparietal stream and a ventral temporal–frontal stream associated with separate components. Collapsing over the tasks primarily supported by these streams, we characterize the dorsal stream as a form-to-articulation pathway and the ventral stream as a form-to-meaning pathway. This characterization of the division in the data reflects both the overlap between tasks supported by the two streams as well as the observation that there is a bias for phonological production tasks supported by the dorsal stream and lexical–semantic comprehension tasks supported by the ventral stream. As such, our findings show a division between two processing routes that underlie human speech processing and provide an empirical foundation for studying potential computational differences that distinguish between the two routes. PMID:27956600

  14. Niche engineering reveals complementary resource use.

    PubMed

    Gable, Jacob T; Crowder, David W; Northfield, Tobin D; Steffan, Shawn A; Snyder, William E

    2012-09-01

    Greater resource use by diverse communities might result from species occupying complementary niches. Demonstrating niche complementarity among species is challenging, however, due to the difficulty in relating differences between species in particular traits to their use of complementary resources. Here, we overcame this obstacle by exploiting plastic foraging behavior in a community of predatory insects common on Brassica oleracea plants in Washington, USA. These predators complemented one another by partitioning foraging space, with some species foraging primarily along leaf edges and others at leaf centers. We hypothesized that emergent biodiversity effects would occur when predators partitioned foraging space on leaves, but not when spatial complementarity was dampened. Indeed, on intact leaves, edge- and center-foraging predators combined to kill more prey than any single predator species could by itself. These emergent diversity effects, however, disappeared on plants damaged by the caterpillar Plutella xylostella. Caterpillar chew-holes brought edge habitats to the center of leaves, so that all predator species could attack aphids anywhere on plants. With spatial niche differences diminished, there were no benefits of predator diversity; the most voracious single predator species killed the most aphids. Thus, caterpillar herbivory determined whether multi-predator-species effects reflected complementarity or species' individual impacts. Our study provides direct evidence for a causative relationship between niche differentiation and increased resource consumption by diverse communities, as revealed by ecological engineers that homogenize the foraging environment.

  15. Revealing the values behind convenience food consumption.

    PubMed

    Botonaki, Anna; Mattas, Konstadinos

    2010-12-01

    The increasing importance of convenience in consumer food choices has attracted researchers' interest. In the effort to understand how convenience affects consumers' food preferences, values are believed to play an important role. The present study attempts to examine the way personal values suggested by Schwartz (1992) are associated with behaviour and attitudes regarding convenience food. A number of constructs describing food related attitudes and behaviours were developed and their relationship with personal values was analyzed following the methodology proposed by Brunsø, Scholderer, and Grunert (2004). Data were collected through a questionnaire survey from a random sample of consumers in Thessaloniki city, Greece. The results reveal that convenience food consumption and convenience orientation in the food domain are mainly connected with values that motivate people to seek new experiences, act independently and enhance their own personal interests, while are in conflict with values of conservation and self-transcendence. The opposite holds for other food related attitudes and behaviours like involvement with cooking and variety in diet. The findings seem to be of particular interest not only for marketers of food products, but also for food policy makers.

  16. The IC 342-Maffei 1 Group Revealed

    NASA Astrophysics Data System (ADS)

    McCall, M. L.; Buta, R.

    1996-12-01

    Deep wide-field CCD images of thirteen members of the IC 342-Maffei 1 Group in the Northern Milky Way have been acquired in the Johnson V and Cousins I photometric systems. The observations were obtained with the Kitt Peak Burrell-Schmidt telescope in Arizona during six nights in November 1995. Almost none of these galaxies was effectively studied in the past because of the heavy foreground extinction and significant foreground star contamination in the direction of the group. The tens of thousands of foreground stars included on the Schmidt images have been successfully subtracted using DAOPHOT, revealing the true extent and total brightness of most of the galaxies for the first time. In the absence of galactic extinction, Maffei 1, Maffei 2, and IC 342 would be among the five brightest galaxies in the northern sky, and both Maffei 1 and IC 342 would subtend angles as large as the full Moon. The results are critical for assessing the degree to which the group influenced the dynamical evolution of the Local Group. In this poster, we will present deep photographs, total magnitudes and color indices, luminosity profiles, and distance estimates for the member galaxies.

  17. Community structure revealed by phase locking.

    PubMed

    Zhou, Ming-Yang; Zhuo, Zhao; Cai, Shi-min; Fu, Zhongqian

    2014-09-01

    Community structure can naturally emerge in paths to synchronization, and scratching it from the paths is a tough issue that accounts for the diverse dynamics of synchronization. In this paper, with assumption that the synchronization on complex networks is made up of local and collective processes, we proposed a scheme to lock the local synchronization (phase locking) at a stable state, meanwhile, suppress the collective synchronization based on Kuramoto model. Through this scheme, the network dynamics only contains the local synchronization, which suggests that the nodes in the same community synchronize together and these synchronization clusters well reveal the community structure of network. Furthermore, by analyzing the paths to synchronization, the relations or overlaps among different communities are also obtained. Thus, the community detection based on the scheme is performed on five real networks and the observed community structures are much more apparent than modularity-based fast algorithm. Our results not only provide a deep insight to understand the synchronization dynamics on complex network but also enlarge the research scope of community detection.

  18. Caged Naloxone Reveals Opioid Signaling Deactivation Kinetics

    PubMed Central

    Banghart, Matthew R.; Shah, Ruchir C.; Lavis, Luke D.

    2013-01-01

    The spatiotemporal dynamics of opioid signaling in the brain remain poorly defined. Photoactivatable opioid ligands provide a means to quantitatively measure these dynamics and their underlying mechanisms in brain tissue. Although activation kinetics can be assessed using caged agonists, deactivation kinetics are obscured by slow clearance of agonist in tissue. To reveal deactivation kinetics of opioid signaling we developed a caged competitive antagonist that can be quickly photoreleased in sufficient concentrations to render agonist dissociation effectively irreversible. Carboxynitroveratryl-naloxone (CNV-NLX), a caged analog of the competitive opioid antagonist NLX, was readily synthesized from commercially available NLX in good yield and found to be devoid of antagonist activity at heterologously expressed opioid receptors. Photolysis in slices of rat locus coeruleus produced a rapid inhibition of the ionic currents evoked by multiple agonists of the μ-opioid receptor (MOR), but not of α-adrenergic receptors, which activate the same pool of ion channels. Using the high-affinity peptide agonist dermorphin, we established conditions under which light-driven deactivation rates are independent of agonist concentration and thus intrinsic to the agonist-receptor complex. Under these conditions, some MOR agonists yielded deactivation rates that are limited by G protein signaling, whereas others appeared limited by agonist dissociation. Therefore, the choice of agonist determines which feature of receptor signaling is unmasked by CNV-NLX photolysis. PMID:23960100

  19. Biosignatures as revealed by spectropolarimetry of Earthshine.

    PubMed

    Sterzik, Michael F; Bagnulo, Stefano; Palle, Enric

    2012-02-29

    Low-resolution intensity spectra of Earth's atmosphere obtained from space reveal strong signatures of life ('biosignatures'), such as molecular oxygen and methane with abundances far from chemical equilibrium, as well as the presence of a 'red edge' (a sharp increase of albedo for wavelengths longer than 700 nm) caused by surface vegetation. Light passing through the atmosphere is strongly linearly polarized by scattering (from air molecules, aerosols and cloud particles) and by reflection (from oceans and land). Spectropolarimetric observations of local patches of Earth's sky light from the ground contain signatures of oxygen, ozone and water, and are used to characterize the properties of clouds and aerosols. When applied to exoplanets, ground-based spectropolarimetry can better constrain properties of atmospheres and surfaces than can standard intensity spectroscopy. Here we report disk-integrated linear polarization spectra of Earthshine, which is sunlight that has been first reflected by Earth and then reflected back to Earth by the Moon. The observations allow us to determine the fractional contribution of clouds and ocean surface, and are sensitive to visible areas of vegetation as small as 10 per cent. They represent a benchmark for the diagnostics of the atmospheric composition, mean cloud height and surfaces of exoplanets.

  20. Balance Trees Reveal Microbial Niche Differentiation.

    PubMed

    Morton, James T; Sanders, Jon; Quinn, Robert A; McDonald, Daniel; Gonzalez, Antonio; Vázquez-Baeza, Yoshiki; Navas-Molina, Jose A; Song, Se Jin; Metcalf, Jessica L; Hyde, Embriette R; Lladser, Manuel; Dorrestein, Pieter C; Knight, Rob

    2017-01-01

    Advances in sequencing technologies have enabled novel insights into microbial niche differentiation, from analyzing environmental samples to understanding human diseases and informing dietary studies. However, identifying the microbial taxa that differentiate these samples can be challenging. These issues stem from the compositional nature of 16S rRNA gene data (or, more generally, taxon or functional gene data); the changes in the relative abundance of one taxon influence the apparent abundances of the others. Here we acknowledge that inferring properties of individual bacteria is a difficult problem and instead introduce the concept of balances to infer meaningful properties of subcommunities, rather than properties of individual species. We show that balances can yield insights about niche differentiation across multiple microbial environments, including soil environments and lung sputum. These techniques have the potential to reshape how we carry out future ecological analyses aimed at revealing differences in relative taxonomic abundances across different samples. IMPORTANCE By explicitly accounting for the compositional nature of 16S rRNA gene data through the concept of balances, balance trees yield novel biological insights into niche differentiation. The software to perform this analysis is available under an open-source license and can be obtained at https://github.com/biocore/gneiss. Author Video: An author video summary of this article is available.

  1. Balance Trees Reveal Microbial Niche Differentiation

    PubMed Central

    Morton, James T.; Sanders, Jon; Quinn, Robert A.; McDonald, Daniel; Gonzalez, Antonio; Vázquez-Baeza, Yoshiki; Navas-Molina, Jose A.; Metcalf, Jessica L.; Hyde, Embriette R.; Lladser, Manuel; Dorrestein, Pieter C.

    2017-01-01

    ABSTRACT Advances in sequencing technologies have enabled novel insights into microbial niche differentiation, from analyzing environmental samples to understanding human diseases and informing dietary studies. However, identifying the microbial taxa that differentiate these samples can be challenging. These issues stem from the compositional nature of 16S rRNA gene data (or, more generally, taxon or functional gene data); the changes in the relative abundance of one taxon influence the apparent abundances of the others. Here we acknowledge that inferring properties of individual bacteria is a difficult problem and instead introduce the concept of balances to infer meaningful properties of subcommunities, rather than properties of individual species. We show that balances can yield insights about niche differentiation across multiple microbial environments, including soil environments and lung sputum. These techniques have the potential to reshape how we carry out future ecological analyses aimed at revealing differences in relative taxonomic abundances across different samples. IMPORTANCE By explicitly accounting for the compositional nature of 16S rRNA gene data through the concept of balances, balance trees yield novel biological insights into niche differentiation. The software to perform this analysis is available under an open-source license and can be obtained at https://github.com/biocore/gneiss. Author Video: An author video summary of this article is available. PMID:28144630

  2. Feather corticosterone reveals developmental stress in seabirds.

    PubMed

    Will, Alexis P; Suzuki, Yuya; Elliott, Kyle H; Hatch, Scott A; Watanuki, Yutaka; Kitaysky, Alexander S

    2014-07-01

    In nest-bound avian offspring, food shortages typically trigger a release of the stress hormone corticosterone (CORT). Recent studies indicate that CORT is passively deposited in the tissue of growing feathers and thus may provide an integrated measure of stress incurred during development in the nest. The current hypothesis predicts that, assuming a constant rate of feather growth, elevated CORT circulating in the blood corresponds to higher levels of CORT in feather tissue, but experimental evidence for nutritionally stressed chicks is lacking. Here, we examined how food limitation affects feather CORT content in the rhinoceros auklet (Cerorhinca moncerata). We (i) used captive chicks reared on control versus restricted diets, and (ii) applied this technique to free-living chicks with unknown nutritional histories that fledged at three separate colonies. We found that (i) feather growth was not affected by experimentally induced nutritional stress; (ii) captive chicks raised on a restricted diet had higher levels of CORT in their primary feathers; (iii) feather CORT deposition is a sensitive method of detecting nutritional stress; and (iv) free-living fledglings from the colony with poor reproductive performance had higher CORT in their primary feathers. We conclude that feather CORT is a sensitive integrated measure revealing the temporal dynamics of food limitations experienced by rhinoceros auklet nestlings. The use of feather CORT may be a powerful endocrine tool in ecological and evolutionary studies of bird species with similar preferential allocation of limited resources to feather development.

  3. Resonant X-Ray Diffraction Study of an Unusually Large Phase Coexistance in Smectic Liquid-Crystal Films

    SciTech Connect

    Pan L.; Pindak R.; Barois, P.; Liu, Z.Q.; McCoy, B.K. & Hyang, C.C.

    2012-01-19

    The recent discovery of the new smectic-C{sub d6}* (SmC{sub d6}*) phase [S. Wang et al. Phys. Rev. Lett. 104 027801 (2010)] also revealed the existence of a noisy region in the temperature window between the SmC{sub d6}* phase and the smectic-C{sub d4}* (SmC{sub d4}*) phase. Characterized by multiple resonant peaks spanning a wide region in Q{sub Z}, the corresponding structure of this temperature window has been a mystery. In this Letter, through a careful resonant x-ray diffraction study and simulations of the diffraction spectra, we show that this region is in fact an unusually large coexistence region of the SmC{sub d6}* phase and the SmC{sub d4}* phase. The structure of the noisy region is found to be a heterogeneous mixture of local SmC{sub d6}* and SmC{sub d4}* orders on the sub-{micro}m scale.

  4. Radio Telescopes Reveal Unseen Galactic Cannibalism

    NASA Astrophysics Data System (ADS)

    2008-06-01

    Radio-telescope images have revealed previously-unseen galactic cannibalism -- a triggering event that leads to feeding frenzies by gigantic black holes at the cores of galaxies. Astronomers have long suspected that the extra-bright cores of spiral galaxies called Seyfert galaxies are powered by supermassive black holes consuming material. However, they could not see how the material is started on its journey toward the black hole. Optical/Radio Comparison Visible-light (left) and radio (right) image of galaxy pair: Radio image shows gas streaming between galaxies. CREDIT: Kuo et al., NRAO/AUI/NSF Click on image for more graphics. One leading theory said that Seyfert galaxies have been disturbed by close encounters with neighboring galaxies, thus stirring up their gas and bringing more of it within the gravitational reach of the black hole. However, when astronomers looked at Seyferts with visible-light telescopes, only a small fraction showed any evidence of such an encounter. Now, new images of hydrogen gas in Seyferts made using the National Science Foundation's Very Large Array (VLA) radio telescope show the majority of them are, in fact, disturbed by ongoing encounters with neighbor galaxies. "The VLA lifted the veil on what's really happening with these galaxies," said Cheng-Yu Kuo, a graduate student at the University of Virginia. "Looking at the gas in these galaxies clearly showed that they are snacking on their neighbors. This is a dramatic contrast with their appearance in visible starlight," he added. The effect of the galactic encounters is to send gas and dust toward the black hole and produce energy as the material ultimately is consumed. Black holes, concentrations of matter so dense that not even light can escape their gravitational pull, reside at the cores of many galaxies. Depending on how rapidly the black hole is eating, the galaxy can show a wide range of energetic activity. Seyfert galaxies have the mildest version of this activity, while

  5. Revealing atropisomer axial chirality in drug discovery.

    PubMed

    LaPlante, Steven R; Edwards, Paul J; Fader, Lee D; Jakalian, Araz; Hucke, Oliver

    2011-03-07

    An often overlooked source of chirality is atropisomerism, which results from slow rotation along a bond axis due to steric hindrance and/or electronic factors. If undetected or not managed properly, this time-dependent chirality has the potential to lead to serious consequences, because atropisomers can be present as distinct enantiomers or diastereoisomers with their attendant different properties. Herein we introduce a strategy to reveal and classify compounds that have atropisomeric chirality. Energy barriers to axial rotation were calculated using quantum mechanics, from which predicted high barriers could be experimentally validated. A calculated rotational energy barrier of 20 kcal mol(-1) was established as a suitable threshold to distinguish between atropisomers and non-atropisomers with a prediction accuracy of 86%. This methodology was applied to subsets of drug databases in the course of which atropisomeric drugs were identified. In addition, some drugs were exposed that were not yet known to have this chiral attribute. The most valuable utility of this tool will be to predict atropisomerism along the drug discovery pathway. When used in concert with our compound classification scheme, decisions can be made during early discovery stages such as "hit-to-lead" and "lead optimization," to foresee and validate the presence of atropisomers and to exercise options of removing, further stabilizing, or rendering the chiral axis of interest more freely rotatable via SAR design, thereby decreasing this potential liability within a compound series. The strategy can also improve drug development plans, such as determining whether a drug or series should be developed as a racemic mixture or as an isolated single compound. Moreover, the work described herein can be extended to other chemical fields that require the assessment of potential chiral axes.

  6. Saturn Probe: Revealing Solar System Origins

    NASA Astrophysics Data System (ADS)

    Spilker, T. R.

    2015-12-01

    Comparative studies of the gas giant and ice giant planets are needed to reliably discriminate among competing theories of the origin and evolution of giant planets and the solar system, but we lack critical measurements. A Saturn atmospheric entry probe mission would fill a vital part of that gap, allowing comparative studies of Jupiter and Saturn, providing the basis for later comparisons with the ice giants Uranus and Neptune, and informing studies of extrasolar planetary systems now being characterized. The Galileo Probe mission provided the first in situ studies of Jupiter's atmosphere. Similar measurements at Saturn, Uranus and Neptune would provide an important comparative planetology context for the Galileo results. Cassini's "Proximal Orbits" in 2017 will reveal Saturn's internal structure to complement the Juno mission's similar measurements at Jupiter. A Saturn entry probe, complementing the Galileo Probe investigations at Jupiter, would complete a solid basis for improved understanding of both Jupiter and Saturn, an important stepping stone to understanding Uranus and Neptune and solar system formation and evolution. The 2012 Decadal Survey ("DS") added Saturn Probe science objectives to NASA's New Frontiers Program: highest-priority Tier 1 objectives any New Frontiers implementation must achieve, and Tier 2, high priority but lower than Tier 1. A DS mission concept study using extremely conservative assumptions concluded that a Saturn Probe project could fit within New Frontiers resource constraints, giving a PI confidence that they could pursue some Tier 2 objectives, customizing for the proper balance of science return, science team composition, procured or contributed instruments, etc. Contributed instruments could significantly enhance the payload and the science team for greater science return. They also provide international collaboration opportunities, with science benefits well demonstrated by missions such as Cassini-Huygens and Rosetta.

  7. Quadrupole transitions revealed by Borrmann spectroscopy.

    PubMed

    Pettifer, Robert F; Collins, Stephen P; Laundy, David

    2008-07-10

    The Borrmann effect-a dramatic increase in transparency to X-ray beams-is observed when X-rays satisfying Bragg's law diffract through a perfect crystal. The minimization of absorption seen in the Borrmann effect has been explained by noting that the electric field of the X-ray beam approaches zero amplitude at the crystal planes, thus avoiding the atoms. Here we show experimentally that under conditions of absorption suppression, the weaker electric quadrupole absorption transitions are effectively enhanced to such a degree that they can dominate the absorption spectrum. This effect can be exploited as an atomic spectroscopy technique; we show that quadrupole transitions give rise to additional structure at the L(1), L(2) and L(3) absorption edges of gadolinium in gadolinium gallium garnet, which mark the onset of excitations from 2s, 2p(1/2) and 2p(3/2) atomic core levels, respectively. Although the Borrmann effect served to underpin the development of the theory of X-ray diffraction, this is potentially the most important experimental application of the phenomenon since its first observation seven decades ago. Identifying quadrupole features in X-ray absorption spectroscopy is central to the interpretation of 'pre-edge' spectra, which are often taken to be indicators of local symmetry, valence and atomic environment. Quadrupolar absorption isolates states of different symmetries to that of the dominant dipole spectrum, and typically reveals orbitals that dominate the electronic ground-state properties of lanthanides and 3d transition metals, including magnetism. Results from our Borrmann spectroscopy technique feed into contemporary discussions regarding resonant X-ray diffraction and the nature of pre-edge lines identified by inelastic X-ray scattering. Furthermore, because the Borrmann effect has been observed in photonic materials, it seems likely that the quadrupole enhancement reported here will play an important role in modern optics.

  8. NASA's Hyperwall Revealing the Big Picture

    NASA Technical Reports Server (NTRS)

    Sellers, Piers

    2011-01-01

    NASA:s hyperwall is a sophisticated visualization tool used to display large datasets. The hyperwall, or video wall, is capable of displaying multiple high-definition data visualizations and/or images simultaneously across an arrangement of screens. Functioning as a key component at many NASA exhibits, the hyperwall is used to help explain phenomena, ideas, or examples of world change. The traveling version of the hyperwall is typically comprised of nine 42-50" flat-screen monitors arranged in a 3x3 array (as depicted below). However, it is not limited to monitor size or number; screen sizes can be as large as 52" and the arrangement of screens can include more than nine monitors. Generally, NASA satellite and model data are used to highlight particular themes in atmospheric, land, and ocean science. Many of the existing hyperwall stories reveal change across space and time, while others display large-scale still-images accompanied by descriptive, story-telling captions. Hyperwall content on a variety of Earth Science topics already exists and is made available to the public at: eospso.gsfc.nasa.gov/hyperwall. Keynote and PowerPoint presentations as well as Summary of Story files are available for download on each existing topic. New hyperwall content and accompanying files will continue being developed to promote scientific literacy across a diverse group of audience members. NASA invites the use of content accessible through this website but requests the user to acknowledge any and all data sources referenced in the content being used.

  9. Chemical provinces reveal Elysium Volcano's compositional evolution

    NASA Astrophysics Data System (ADS)

    Susko, D. A.; Karunatillake, S.; Wray, J. J.; Skok, J. R.; Hurowitz, J.; Ojha, L.; Judice, T.; Bently, R. O. J.

    2014-12-01

    Chemical provinces of Mars became definable[1-3] with the maps of elemental mass fractions generated with Mars Odyssey Gamma Ray Spectrometer (GRS) data[4,5]. Previous work highlighted the Elysium lava flow province as anomalous, with a depletion in K and Th relative to the average crust in the rest of Mars (ROM).[3] We characterize the elemental composition, geology, and geomorphology of the region to constrain the processes that have contributed to its evolution. We compare SE Elysium with its North West lava fields, advancing prior work on thermal evolution of the martian mantle.[6] Lava fields at both sites probably source from Elysium eruptions. Both show similar Si content, as well as a Ca-enrichment compared to ROM, consistent with prior models.[6,7] Nevertheless, the two fields are compositionally distinct from each other, with NW Elysium decisively depleted in Ca and Fe, but enriched in K and Th. Such distinctness, in elements that reflect magmatic fractionation, reveals the possibility that a single volcanic complex on Mars may evolve rapidly during the Amazonian era, causing variable flow compositions. Interestingly, a chemical province containing volcanics that is contemporaneous with Elysium, overlaps the Tharsis region.[3] Unlike Elysium, the K and Th distributions within Tharsis are indistinguishable from ROM. Meanwhile, the mass fraction signature in Tharsis is enriched in Cl and depleted in Si. Such contrast, in chemical anomalies between volcanic constructs of similar age, may indicate that the depletion of K and Th in SE Elysium did not arise from temporal evolution of the mantle. [1] Taylor, G. et al. Geology 38, 183-186, 2010 [2] Gasnault, O. et al. 207, 226-247, 2010 [3] Karunatillake, S. et al. J. Geophys. Res. 114, E12001, 2009 [4] Boynton, W. V. et al. J. Geophys. Res. 112, E12S99, 2007 [5] Feldman, W. C. et al. J. Geophys. Res. 109, E09006, 2004 [6] Baratoux, D. et al. Nature 472, 338-41, 2011 [7] Balta, J. et al. Geology 41, 1115

  10. Planetary Interior Structure Revealed by Spin Dynamics

    NASA Astrophysics Data System (ADS)

    Margot, J.; Peale, S. J.; Jurgens, R. F.; Slade, M. A.; Holin, I. V.

    2002-12-01

    The spin state of a planet depends on the distribution of mass within the interior, gradual and discrete changes in its moments of inertia, dissipation mechanisms at the surface and below, and external torques. Detailed measurements of the spin dynamics can therefore reveal much about planetary interior structure, interactions at the core-mantle and atmosphere-surface boundaries, and mass redistribution events. Studies of the spin precession, polar wobble, and length of day variations have been used to determine Earth's moments of inertia and rigidity and to study the effects of atmospheric angular momentum changes, post-glacial rebound, and large earthquakes. In planetary investigations the spin measurements are particularly important because other means of constraining interior properties require in-situ or orbiting sensors (e.g. seismometers, magnetometers, and Doppler tracking of spacecraft). Here we describe the successful implementation of a new Earth-based radar technique (Holin, 1992) that provides spin state measurements with unprecedented accuracy. Our first observations were designed to characterize Mercury's core. Peale (1976) showed that the measurement of four quantities (the obliquity of the planet, the amplitude of its longitude librations, and the second-degree gravitational harmonics) are sufficient to determine the size and state of Mercury's core. The existence of a molten core would place strong constraints on the thermal and rotational histories of the planet, with profound implications for the composition and rotation state of the planet at the time of formation. A solid core would have a fundamental impact on theories of planetary magnetic field generation. We observed Mercury with the Goldstone radar and the Green Bank Telescope in May-June 2002. We illuminated the planet with a monochromatic signal, recorded the scattered power at the two antennas, and cross-correlated the echoes in the time domain. We obtained strong correlations which

  11. Microradiometers Reveal Ocean Health, Climate Change

    NASA Technical Reports Server (NTRS)

    2013-01-01

    When NASA researcher Stanford Hooker is in the field, he pays close attention to color. For Hooker, being in the field means being at sea. On one such research trip to the frigid waters of the Arctic, with a Coast Guard icebreaker looming nearby and the snow-crusted ice shelf a few feet away, Hooker leaned over the edge of his small boat and lowered a tethered device into the bright turquoise water, a new product devised by a NASA partner and enabled by a promising technology for oceanographers and atmospheric scientists alike. Color is a function of light. Pure water is clear, but the variation in color observed during a visit to the beach or a flight along a coastline depends on the water s depth and the constituents in it, how far down the light penetrates and how it is absorbed and scattered by dissolved and suspended material. Hooker cares about ocean color because of what it can reveal about the health of the ocean, and in turn, the health of our planet. "The main thing we are interested in is the productivity of the water," Hooker says. The seawater contains phytoplankton, microscopic plants, which are the food base for the ocean s ecosystems. Changes in the water s properties, whether due to natural seasonal effects or human influence, can lead to problems for delicate ecosystems such as coral reefs. Ocean color can inform researchers about the quantities and distribution of phytoplankton and other materials, providing clues as to how the world ocean is changing. NASA s Coastal Zone Color Scanner, launched in 1978, was the first ocean color instrument flown on a spacecraft. Since then, the Agency s ocean color research capabilities have become increasingly sophisticated with the launch of the SeaWiFS instrument in 1997 and the twin MODIS instruments carried into orbit on NASA s Terra (1999) and Aqua (2002) satellites. The technology provides sweeping, global information on ocean color on a scale unattainable by any other means. One issue that arises from

  12. Pressure-temperature microscopy of petroleum-derived hydrocarbons

    SciTech Connect

    Perrotta, A.J.; McCullough, J.P.; Beuther, H.

    1983-03-01

    An apparatus allowing microscopy of petroleum derived hydrocarbons at pressures and temperatures comparable to those encountered in the hydroprocessing of coal and oil, and its use in the study of pressure and temperature effects on the crystallization behavior of a decant oil-derived air blown-pitch (DODAB) is described in this paper. Crystallization of the mesophase from aromatic rich precursors can be used as a tracking vehicle whose anisotropy allows easy detection under the polarizing microscope. Mesophase formation pressure dependence using N/sub 2/ and H/sub 2/ reveals that there is a chemical effect associated with H/sub 2/ since N/sub 2/ pressure to 1900 psig had no effect on mesophase formation. In both cases a fine grained anisotropic phase forms initially at the crystallization temperature and 25 psig. In pyrolyzed material mesophase formation under N/sub 2/ is a pressure dependent transformation.

  13. The lower atmosphere of Pluto revealed

    NASA Astrophysics Data System (ADS)

    2009-03-01

    ), attached to ESO's Very Large Telescope, have now revealed that the atmosphere as a whole, not just the upper atmosphere, has a mean temperature of minus 180 degrees Celsius, and so it is indeed "much hotter" than the surface. In contrast to the Earth's atmosphere [2], most, if not all, of Pluto's atmosphere is thus undergoing a temperature inversion: the temperature is higher, the higher in the atmosphere you look. The change is about 3 to 15 degrees per kilometre. On Earth, under normal circumstances, the temperature decreases through the atmosphere by about 6 degrees per kilometre. "It is fascinating to think that with CRIRES we are able to precisely measure traces of a gas in an atmosphere 100 000 times more tenuous than the Earth's, on an object five times smaller than our planet and located at the edge of the Solar System," says co-author Hans-Ulrich Käufl. "The combination of CRIRES and the VLT is almost like having an advanced atmospheric research satellite orbiting Pluto." The reason why Pluto's surface is so cold is linked to the existence of Pluto's atmosphere, and is due to the sublimation of the surface ice; much like sweat cools the body as it evaporates from the surface of the skin, this sublimation has a cooling effect on the surface of Pluto. In this respect, Pluto shares some properties with comets, whose coma and tails arise from sublimating ice as they approach the Sun. The CRIRES observations also indicate that methane is the second most common gas in Pluto's atmosphere, representing half a percent of the molecules. "We were able to show that these quantities of methane play a crucial role in the heating processes in the atmosphere and can explain the elevated atmospheric temperature," says Lellouch. Two different models can explain the properties of Pluto's atmosphere. In the first, the astronomers assume that Pluto's surface is covered with a thin layer of methane, which will inhibit the sublimation of the nitrogen frost. The second scenario invokes

  14. Dramatic Outburst Reveals Nearest Black Hole

    NASA Astrophysics Data System (ADS)

    2000-01-01

    Sgr. The radio observations revealed the presence of a jet escaping from the system at mind-boggling speeds. Only three other galactic X-ray stellar systems have been found to eject material at such speeds. They have been dubbed "microquasars" because, on a smaller scale, they resemble quasars, which lie at the hearts of distant galaxies and also spew out high-velocity jets of particles. In galaxy-core quasars, the black holes are millions of times more massive than the Sun; in the more nearby microquasars the black holes are roughly three to twenty times more massive than the Sun. The extremely high velocity of the jets suggests that their origin lies close to the event horizon of a black hole. Microquasar activity is thought to arise when the black hole in the binary system draws material away from its companion star. The material surrounding the black hole forms a rapidly spinning disk called an accretion disk. This disk is heated by friction to millions of degrees, causing it to emit X-rays. As spiralling gas moves into the gravity well of the black hole, it moves faster and faster. Magnetic fields in the disk are believed to expel the charged subatomic particles at speeds close to that of light. As the charged particles interact with the magnetic fields, they emit radio waves. If some of the material escapes by being magnetically expelled into space, the matter may continue moving at the tremendous speed it had attained near the black hole. After their ejection, the jets of particles expand and cool, fading from astronomers' view. V4641 Sgr excites astronomers because it is close and because it acted so differently from other microquasars. In other microquasars, outbursts have dimmed more slowly over weeks or months rather than hours. "There's something fundamentally different about this one; it's more extreme than any other example," Hjellming said. "And because this system happens to be so close to us, `it is very likely that there are more objects like V4641

  15. 21 CFR 1.21 - Failure to reveal material facts.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Failure to reveal material facts. 1.21 Section 1... GENERAL ENFORCEMENT REGULATIONS General Labeling Requirements § 1.21 Failure to reveal material facts. (a) Labeling of a food, drug, device, or cosmetic shall be deemed to be misleading if it fails to reveal...

  16. 21 CFR 1.21 - Failure to reveal material facts.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Failure to reveal material facts. 1.21 Section 1... GENERAL ENFORCEMENT REGULATIONS General Labeling Requirements § 1.21 Failure to reveal material facts. (a) Labeling of a food, drug, device, or cosmetic shall be deemed to be misleading if it fails to reveal...

  17. Quantifying the transport properties of lipid mesophases by theoretical modelling of diffusion experiments.

    PubMed

    Antognini, Luca M; Assenza, Salvatore; Speziale, Chiara; Mezzenga, Raffaele

    2016-08-28

    Lyotropic Liquid Crystals (LLCs) are a class of lipid-based membranes with a strong potential for drug-delivery employment. The characterization and control of their transport properties is a central issue in this regard, and has recently prompted a notable volume of research on the topic. A promising experimental approach is provided by the so-called diffusion setup, where the drug molecules diffuse from a feeding chamber filled with water to a receiving one passing through a LLC. In the present work we provide a theoretical framework for the proper description of this setup, and validate it by means of targeted experiments. Due to the inhomogeneity of the system, a rich palette of different diffusion dynamics emerges from the interplay of the different time- and lengthscales thereby present. Our work paves the way to the employment of diffusion experiments to quantitatively characterize the transport properties of LLCs, and provides the basic tools for device diffusion setups with controlled kinetic properties.

  18. Pyrolysis in the mesophase: a chemist's approach toward preparing carbon nano- and microparticles.

    PubMed

    Gherghel, Lileta; Kübel, Christian; Lieser, Günter; Räder, Hans-Joachim; Müllen, Klaus

    2002-11-06

    A mild pyrolytic method is proposed for the generation of different carbon micro- and nanoparticles that are either unprecedented or have never been reported under the present experimental conditions. A hexa-alkyl-substituted hexa-peri-hexabenzocoronene serves as a graphite-like starting compound that melts into a discotic liquid crystalline phase prior to heat-induced cross-linking and dehydrogenation. An essential feature of the process is that the liquid crystalline order persists even above 400 degrees C, i.e., during alkyl chain cleavage. The present approach bears a resemblance to carbomesophase formation during graphitization starting from pitch. The pyrolysis products are characterized by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, optical microscopy, selected area electron diffraction (SAED), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM).

  19. Detailed analyses of FCC decant oil as a starting feedstock for mesophase pitch

    SciTech Connect

    Mochida, I.; Korai, Y.; Hieida, T. ); Azuma, A.; Kitajima, E. )

    1991-01-01

    Four typical DOs supplied from Japanese refineries were analyzed in detail by GC, FD-MS {sup 1}H and {sup 13}C-NMR after the fractionations by column chromatography. A DO carries 30% saturate and 70% aromatic fractions. The saturate consisted principally of the straight paraffins. The aromatic fraction was separated into five substractions (AR1 - AR5) of which contents distributed rather evenly, the middle fraction (AR 3) occupying the largest of 30%. The aromatic components had consisted of aromatic rings from 2(AR1) to 4(AR4+5), of some aryl-aryl linkages and naphthenic rings being included. The lighter aromatic fraction carried more alkyl groups, enhance its solubility and elution in the column. B DO appeared heaviest among the DOs in the present study. The oils carried only 10% of the saturate and 75% of AR3-AR5 aromatic subfractions. Its saturate was of carried rather short chains and more isoparaffins. Its aromatic components had very similar aromatic units to those of A DO in the same subfraction, although the heaviest fraction of the former once contained also a small portion of 6 aromatic rings.

  20. Volume and porosity thermal regulation in lipid mesophases by coupling mobile ligands to soft membranes

    NASA Astrophysics Data System (ADS)

    Parolini, Lucia; Mognetti, Bortolo M.; Kotar, Jurij; Eiser, Erika; Cicuta, Pietro; di Michele, Lorenzo

    2015-01-01

    Short DNA linkers are increasingly being exploited for driving-specific self-assembly of Brownian objects. DNA-functionalized colloids can assemble into ordered or amorphous materials with tailored morphology. Recently, the same approach has been applied to compliant units, including emulsion droplets and lipid vesicles. The liquid structure of these substrates introduces new degrees of freedom: the tethers can diffuse and rearrange, radically changing the physics of the interactions. Unlike droplets, vesicles are extremely deformable and DNA-mediated adhesion causes significant shape adjustments. We investigate experimentally the thermal response of pairs and networks of DNA-tethered liposomes and observe two intriguing and possibly useful collective properties: negative thermal expansion and tuneable porosity of the liposome networks. A model providing a thorough understanding of this unexpected phenomenon is developed, explaining the emergent properties out of the interplay between the temperature-dependent deformability of the vesicles and the DNA-mediated adhesive forces.

  1. Probing influence of mesophasic transformation on performance of self-emulsifying system: effect of ion.

    PubMed

    Patil, Sharvil S; Venugopal, Edakkal; Bhat, Suresh; Mahadik, Kakasaheb R; Paradkar, Anant R

    2012-02-06

    Self-emulsifying systems are mixtures of oils and surfactants, ideally isotropic, sometimes including cosolvents, which emulsify under conditions of gentle agitation, similar to those which would be encountered in the gastrointestinal tract. The process of self-emulsification has remained the center of attraction for most researchers. Controlled hydration of self-emulsifying systems shows formation of an intermediate gel phase which upon rupture forms an emulsion. Current work was undertaken to understand and explore the microstructural properties of intermediate gel phase which are believed to influence the performance (droplet size) of the final formulation. The effect of additives on microstructural properties of intermediate gel phase has also been investigated. Microstructural elucidation of hydrated samples of intermediate regimes was done by using techniques such as small angle X-ray scattering, differential scanning calorimetry and rheology. Samples from intermediate regimes showed formation of local lamellar structure which swelled with hydration. In the present work, the effect of addition of salt form of naproxen (sodium and potassium) and naproxen (base) on microstructural properties of intermediate regimes was investigated. Systems containing naproxen salts formed larger droplets whereas naproxen base formed smaller ones. Microstructural properties of intermediate lamellar structures were well correlated with performance of the final formulation. The current studies indicate that by controlling the properties of intermediate regimes optimized formulations with desired performance can be tailor-made.

  2. Diffusion, molecular separation, and drug delivery from lipid mesophases with tunable water channels.

    PubMed

    Negrini, Renata; Mezzenga, Raffaele

    2012-11-27

    Lyotropic liquid crystals characterized by a bicontinuous cubic phase (BCP) have a structure characterized by interpenetrated water channels following triply periodic minimal surfaces, which can be stable in excess water conditions and thus suitable in a multitude of applications. The control of the water channels size in these systems has a direct impact on their use for drug delivery, crystallization, and membrane separation processes. In this work we carry out systematic diffusion studies to show how the control on the water channel dimensions directly correlates with the release and separation performance of bicontinuous cubic phases. Specifically, we tune the water channels diameter of the monolinolein/water system by adding different amounts of sucrose stearate, which, having hydration-enhancing properties, can shift the boundaries of the phase diagram. We then design a model bicontinuous cubic phase lipidic membrane of the Im3m space group, having a sugar ester to monolinolein ratio of 20%, and we follow the diffusion within its water channels, by using molecules that differ systematically in size and molecular conformation, and we demonstrate, for each class of molecules, a diffusion-enhanced process upon increase of the water channel diameter. Finally, we also show the ability of the bicontinuous cubic phase to efficiently and selectively separate nanoparticles of a target size, by choosing an amount of sucrose stearate for which the water channel diameter and the nanoparticle dimensions match, demonstrating the possible use of these systems as filtering membranes of tunable molecular cutoff.

  3. Microstructural Studies of In-Situ Mesophase Transformation in the Fabrication of Carbon-Carbon Composites

    DTIC Science & Technology

    2005-03-01

    materials for lithium ion batteries . The principle behind the impregnation with in-situ transformation process is that a wetting molten monomer...catalyst mixture. Naphthalene was the precursor monomer, and aluminum chloride was chosen as the catalyst. Even though AlCl3 was retained in the...Distribution Stmt: Approved for public release; distribution unlimited 3.3.1. Naphthalene and Aluminum Chloride Catalyst The increase in

  4. Volume and porosity thermal regulation in lipid mesophases by coupling mobile ligands to soft membranes

    PubMed Central

    Parolini, Lucia; Mognetti, Bortolo M.; Kotar, Jurij; Eiser, Erika; Cicuta, Pietro; Di Michele, Lorenzo

    2015-01-01

    Short DNA linkers are increasingly being exploited for driving-specific self-assembly of Brownian objects. DNA-functionalized colloids can assemble into ordered or amorphous materials with tailored morphology. Recently, the same approach has been applied to compliant units, including emulsion droplets and lipid vesicles. The liquid structure of these substrates introduces new degrees of freedom: the tethers can diffuse and rearrange, radically changing the physics of the interactions. Unlike droplets, vesicles are extremely deformable and DNA-mediated adhesion causes significant shape adjustments. We investigate experimentally the thermal response of pairs and networks of DNA-tethered liposomes and observe two intriguing and possibly useful collective properties: negative thermal expansion and tuneable porosity of the liposome networks. A model providing a thorough understanding of this unexpected phenomenon is developed, explaining the emergent properties out of the interplay between the temperature-dependent deformability of the vesicles and the DNA-mediated adhesive forces. PMID:25565580

  5. Observation of an unprecedented body centered cubic micellar mesophase from rod-coil molecules.

    PubMed

    Lee, Eunji; Ryu, Ja-Hyoung; Park, Myoung-Hwan; Lee, Myongsoo; Han, Kyung-Hee; Chung, Yeon-Wook; Cho, Byoung-Ki

    2007-07-28

    We have demonstrated that rod-coil molecules based on a tetra-p-phenylene rod and a poly(propylene oxide) coil self-assemble into an unprecedented body centered cubic micellar structure in the melt, through detailed morphological analysis by X-ray scattering and transmission electron microscopy experiments.

  6. Nonequilibrium effects in self-assembled mesophase materials: unexpected supercooling effects for cubosomes and hexosomes.

    PubMed

    Dong, Yao-Da; Tilley, Adam J; Larson, Ian; Lawrence, M Jayne; Amenitsch, Heinz; Rappolt, Michael; Hanley, Tracey; Boyd, Ben J

    2010-06-01

    Polar lipids often exhibit equilibrium liquid crystalline structures in excess water, such as the bicontinuous cubic phases (Q(II)) at low temperatures and inverse hexagonal phase (H(II)) at higher temperatures. In this study, the equilibrium and nonequilibrium phase behavior of glyceryl monooleate (GMO) and phytantriol (PHYT) systems in excess water were investigated using both continuous heating and cooling cycles, and rapid temperature changes. Evolution of the phase structure was followed using small-angle X-ray scattering (SAXS). During cooling, not only was supercooling of the liquid crystalline systems by up to 25 degrees C observed, but evidence for nonequilibrium phase structures (not present on heating; such as the gyroid cubic phase only present at low water content in equilibrium) was also apparent. The nonequilibrium phases were surprisingly stable, with return to equilibrium structure for dispersed submicrometer sized particle systems taking more than 13 h in some cases. Inhibition of phase nucleation was the key to greater supercooling effects observed for the dispersed particles compared to the bulk systems. These findings highlight the need for continued study into the nonequilibrium phase structures for these types of systems, as this may influence performance in applications such as drug delivery.

  7. Graphene as a photothermal actuator for control of lipid mesophase structure.

    PubMed

    Quinn, Matthew D J; Wang, Tao; Du, Joanne D; Boyd, Ben J; Hawley, Adrian; Notley, Shannon M

    2017-01-07

    The optical density of pristine graphene is high and broad in the near infrared region of the electromagnetic spectrum positioning this material as a highly efficient photothermal agent for in vivo applications. In this study, surfactant assisted exfoliated graphene was incorporated within bulk lipid samples of varying lipid types: glyceryl monoether, glyceryl monooleate and phytantriol. The pristine graphene sheets did not disrupt the packing of the liquid crystals while being in sufficiently intimate contact to provide localized heating and induce phase transitions. The phase progressions induced through heating using NIR irradiation of the entrained graphene particles within the bulk liquid crystal were studied using SAXS and confirmed using polarized optical microscopy. Increases in apparent temperature experienced by the matrix of up to 50 °C were observed by establishing a SAXS versus bulk temperature calibration curve allowing in situ measurements. The studies demonstrate the potential for use of graphene as a photothermal actuator across a range of lipid based systems of interest in controlled drug delivery.

  8. Theory and Simulation of Extensional Flow-Induced Biaxiality in Discotic Mesophases

    NASA Astrophysics Data System (ADS)

    Singh, Arvinder P.; Rey, Alejandro D.

    1995-09-01

    Flow-induced biaxiality is simulated for a uniaxial discotic nematic liquid crystal subjected to a constant uniaxial, isothermal, incompressible, irrotational, extensional, three dimensional flow, using a previously presented model [Singh A.P. and Rey A.D., J. Phys. II France 4 (1994) 645]. Numerical and analytical solutions of the director triad (n, m, l), and uniaxial (S) and biaxial (P) alignments are given. The unit sphere description of the director triad is used to discuss and analyze the sensitivity of the director triad trajectories and the coupled alignment (uniaxial and biaxial) relaxations to the initial orientation, nematic potential (U), and to the alignment Deborah number (dimensionless extension rate). The evolution of the director triad is given by the rotation of a moving diad (n, l) around a fixed director (m). When the poles of the orientation unit sphere are along the extension axis, and the equator lies in the compression plane of the flow, it is found that the director diad (n, l) dynamics follow geodesic flow and the trajectories belong to the same meridians (great circles through the poles). The space of stable steady state orientation of the uniaxial director n and the biaxial director m is the whole compression plane (the equator of the unit sphere), while that of the biaxial director l is the extension direction (poles). A high degree extension flow-induced biaxiality is found when the uniaxial director is away from the extension axis and when S is relatively low. The scalar order parameter couplings are captured by analyzing the trajectories in the alignment triangle. Computed scientific visualizations of biaxial molecular orientation distributions are used to correlate the director triad dynamics and the alignment's dynamics. The tensor order parameter is used to calculate the main flow-birefringences, thus providing a direct way to verify the theoretical predictions of this paper.

  9. Nanostructured Monolinolein Miniemulsions as Delivery Systems: Role of the Internal Mesophase on Cytotoxicity and Cell Internalization.

    PubMed

    Guillot, Samuel; Méducin, Fabienne; Poljak, Kristina; Malard, Virginie; Foucault-Collet, Alexandra; Serieye, Sébastien; Pichon, Chantal

    2017-03-08

    Recent advances in nanoparticle systems for improved drug delivery display a great potential for the administration of active molecules. Here, lipid miniemulsions with various internal nanostructures were loaded with the chemotherapeutic agent Paclitaxel. The goal is to assess the impact of internal structures on their efficiency. Previously the structure, the stability and the physico-chemical properties of those carriers were characterized. Modalities of action were addressed by the evaluation of their effects on the tumor cells viability, their cellular uptake by flow cytometry and confocal microscopy detection of fluorescently labeled nanostructured miniemulsions. Nanostructured miniemulsions showed variations in the cell internalization process likely due to differences in the internal structure. All paclitaxel-loaded emulsions were active reservoirs from which Paclitaxel could be released, however bicontinuous cubosomes showed the best efficiency. Considering the fact that these delivery systems can offer a new life to bioactive compounds previously abandoned due to a low aqueous solubility, these data may represent an important step towards the development of new clinical therapeutic strategies against cancers.

  10. What Facial Appearance Reveals Over Time: When Perceived Expressions in Neutral Faces Reveal Stable Emotion Dispositions

    PubMed Central

    Adams, Reginald B.; Garrido, Carlos O.; Albohn, Daniel N.; Hess, Ursula; Kleck, Robert E.

    2016-01-01

    It might seem a reasonable assumption that when we are not actively using our faces to express ourselves (i.e., when we display nonexpressive, or neutral faces), those around us will not be able to read our emotions. Herein, using a variety of expression-related ratings, we examined whether age-related changes in the face can accurately reveal one’s innermost affective dispositions. In each study, we found that expressive ratings of neutral facial displays predicted self-reported positive/negative dispositional affect, but only for elderly women, and only for positive affect. These findings meaningfully replicate and extend earlier work examining age-related emotion cues in the face of elderly women (Malatesta et al., 1987a). We discuss these findings in light of evidence that women are expected to, and do, smile more than men, and that the quality of their smiles predicts their life satisfaction. Although ratings of old male faces did not significantly predict self-reported affective dispositions, the trend was similar to that found for old female faces. A plausible explanation for this gender difference is that in the process of attenuating emotional expressions over their lifetimes, old men reveal less evidence of their total emotional experiences in their faces than do old women. PMID:27445944

  11. Facial cellulitis revealing choreo-acanthocytosis: a case report.

    PubMed

    Samia, Younes; Yosra, Cherif; Foued, Bellazreg; Mouna, Aissi; Olfa, Berriche; Jihed, Souissi; Hammadi, Braham; Mahbouba, Frih-Ayed; Amel, Letaief; Habib, Sfar Mohamed

    2014-01-01

    We report a 62 year-old-man with facial cellulitis revealing choreo-acanthocytosis (ChAc). He showed chorea that started 20 years ago. The orofacial dyskinisia with tongue and cheek biting resulted in facial cellulitis. The peripheral blood smear revealed acanthocytosis of 25%. The overall of chorea, orofacial dyskinetic disorder, peripheral neuropathy, disturbed behavior, acanthocytosis and the atrophy of caudate nuclei was suggestive of a diagnosis of ChAc. To our knowledge no similar cases of facial cellulitis revealing choreo-acanthocytosis (ChAc) were found in a review of the literature.

  12. Everett Weinreb, Photographer, April 1989 FOUNDATION DETAIL REVEALED AS RESULT ...

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

    Everett Weinreb, Photographer, April 1989 FOUNDATION DETAIL REVEALED AS RESULT OF HOUSE DEMOLITION - Irvine Ranch Agricultural Headquarters, Boyd Tenant House, Southeast of Intersection of San Diego & Santa Ana Freeways, Irvine, Orange County, CA

  13. General view of the archaeological site showing excavation and revealing ...

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

    General view of the archaeological site showing excavation and revealing the steps leading down into the eighteenth-century burial vault - Harry Buck House, North of Main Street (14800 Governor Oden Bowie Drive), Upper Marlboro, Prince George's County, MD

  14. Many Ignore Fire Safety at Home, Survey Reveals

    MedlinePlus

    ... medlineplus.gov/news/fullstory_162699.html Many Ignore Fire Safety at Home, Survey Reveals Holiday activities can ... dangerous time of year, but many families ignore fire and burn safety tips, a new survey finds. ...

  15. Genome-Wide Scan Reveals Mutation Associated with Melanoma

    MedlinePlus

    ... historical) Genome-Wide Scan Reveals Mutation Associated with Melanoma A team of international researchers supported by the ... when they divide and grow uncontrollably, develop into melanoma. Also, MITF activity is known to be amplified ...

  16. [Deep vein thrombosis revealing myeloproliferative syndrome in two adolescents].

    PubMed

    Bertrand, A; Heissat, S; Caron, N; Viremouneix, L; Pracros, J-P; Javouhey, E; Lachaux, A; Mialou, V

    2014-05-01

    Deep vein thrombosis occurs in 30% of patients with essential thrombocythemia, but rarely at initial diagnosis. We report two pediatric patients with essential thrombocythemia revealed by atypical deep vein thrombosis. First, a 16-year-old girl presented Budd-Chiari syndrome revealed by a hemorrhagic shock. Clinical exam revealed isolated splenomegaly. A search for thrombophilia found a factor V Leiden homozygous mutation and a Jak2 mutation. Bone marrow biopsy confirmed the diagnosis of a myeloproliferative disorder. The second case, a 17-year-old girl, had a routine examination by her physician that revealed splenomegaly. Ultrasonography displayed thrombus in the splenic and portal vein. An isolated Jak2 mutation was found and a myeloproliferative disorder was confirmed by bone marrow biopsy. The diagnosis of myeloproliferative disorder was made in both patients presenting atypical venous thrombosis with a Jak2 mutation and confirmed by bone marrow biopsy. These initial presentations of myeloproliferative disorders are rare in childhood and possibly underdiagnosed.

  17. Direct sequencing of the human microbiome readily reveals community differences

    PubMed Central

    2010-01-01

    Culture-independent studies of human microbiota by direct genomic sequencing reveal quite distinct differences among communities, indicating that improved sequencing capacity can be most wisely utilized to study more samples, rather than more sequences per sample. PMID:20441597

  18. Revealing the molecular signatures of host-pathogen interactions

    PubMed Central

    2011-01-01

    Advances in sequencing technology and genome-wide association studies are now revealing the complex interactions between hosts and pathogen through genomic variation signatures, which arise from evolutionary co-existence. PMID:22011345

  19. 14. DETAIL VIEW, FLUTED PILASTER AND PANELLED REVEAL IN DOORWAY ...

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

    14. DETAIL VIEW, FLUTED PILASTER AND PANELLED REVEAL IN DOORWAY BETWEEN VESTIBULE AND STAIRHALL (NOTE WOOD GRAINING), WITH SCALE - Bowieville, 522 Church Road South, Leeland, Prince George's County, MD

  20. Revealing of HII-regions in Galaxies with Panoramic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hakopian, S. A.; Balayan, S. K.

    2016-06-01

    Observations intended to investigation and revealing of nodes of processes of nuclear and starforming activity in galaxies were performed via panoramic spectroscopy. Data obtained on Mrk 1050 revealed evidence of starforming activity also outside the central engine of high surface brightness. Two small HII-regions, being likely a part of the chain, are located in the part of the spiral branch coming from the nucleus part.

  1. Revealing physical interaction networks from statistics of collective dynamics.

    PubMed

    Nitzan, Mor; Casadiego, Jose; Timme, Marc

    2017-02-01

    Revealing physical interactions in complex systems from observed collective dynamics constitutes a fundamental inverse problem in science. Current reconstruction methods require access to a system's model or dynamical data at a level of detail often not available. We exploit changes in invariant measures, in particular distributions of sampled states of the system in response to driving signals, and use compressed sensing to reveal physical interaction networks. Dynamical observations following driving suffice to infer physical connectivity even if they are temporally disordered, are acquired at large sampling intervals, and stem from different experiments. Testing various nonlinear dynamic processes emerging on artificial and real network topologies indicates high reconstruction quality for existence as well as type of interactions. These results advance our ability to reveal physical interaction networks in complex synthetic and natural systems.

  2. Camelid genomes reveal evolution and adaptation to desert environments.

    PubMed

    Wu, Huiguang; Guang, Xuanmin; Al-Fageeh, Mohamed B; Cao, Junwei; Pan, Shengkai; Zhou, Huanmin; Zhang, Li; Abutarboush, Mohammed H; Xing, Yanping; Xie, Zhiyuan; Alshanqeeti, Ali S; Zhang, Yanru; Yao, Qiulin; Al-Shomrani, Badr M; Zhang, Dong; Li, Jiang; Manee, Manee M; Yang, Zili; Yang, Linfeng; Liu, Yiyi; Zhang, Jilin; Altammami, Musaad A; Wang, Shenyuan; Yu, Lili; Zhang, Wenbin; Liu, Sanyang; Ba, La; Liu, Chunxia; Yang, Xukui; Meng, Fanhua; Wang, Shaowei; Li, Lu; Li, Erli; Li, Xueqiong; Wu, Kaifeng; Zhang, Shu; Wang, Junyi; Yin, Ye; Yang, Huanming; Al-Swailem, Abdulaziz M; Wang, Jun

    2014-10-21

    Bactrian camel (Camelus bactrianus), dromedary (Camelus dromedarius) and alpaca (Vicugna pacos) are economically important livestock. Although the Bactrian camel and dromedary are large, typically arid-desert-adapted mammals, alpacas are adapted to plateaus. Here we present high-quality genome sequences of these three species. Our analysis reveals the demographic history of these species since the Tortonian Stage of the Miocene and uncovers a striking correlation between large fluctuations in population size and geological time boundaries. Comparative genomic analysis reveals complex features related to desert adaptations, including fat and water metabolism, stress responses to heat, aridity, intense ultraviolet radiation and choking dust. Transcriptomic analysis of Bactrian camels further reveals unique osmoregulation, osmoprotection and compensatory mechanisms for water reservation underpinned by high blood glucose levels. We hypothesize that these physiological mechanisms represent kidney evolutionary adaptations to the desert environment. This study advances our understanding of camelid evolution and the adaptation of camels to arid-desert environments.

  3. Activity screening of environmental metagenomic libraries reveals novel carboxylesterase families

    PubMed Central

    Popovic, Ana; Hai, Tran; Tchigvintsev, Anatoly; Hajighasemi, Mahbod; Nocek, Boguslaw; Khusnutdinova, Anna N.; Brown, Greg; Glinos, Julia; Flick, Robert; Skarina, Tatiana; Chernikova, Tatyana N.; Yim, Veronica; Brüls, Thomas; Paslier, Denis Le; Yakimov, Michail M.; Joachimiak, Andrzej; Ferrer, Manuel; Golyshina, Olga V.; Savchenko, Alexei; Golyshin, Peter N.; Yakunin, Alexander F.

    2017-01-01

    Metagenomics has made accessible an enormous reserve of global biochemical diversity. To tap into this vast resource of novel enzymes, we have screened over one million clones from metagenome DNA libraries derived from sixteen different environments for carboxylesterase activity and identified 714 positive hits. We have validated the esterase activity of 80 selected genes, which belong to 17 different protein families including unknown and cyclase-like proteins. Three metagenomic enzymes exhibited lipase activity, and seven proteins showed polyester depolymerization activity against polylactic acid and polycaprolactone. Detailed biochemical characterization of four new enzymes revealed their substrate preference, whereas their catalytic residues were identified using site-directed mutagenesis. The crystal structure of the metal-ion dependent esterase MGS0169 from the amidohydrolase superfamily revealed a novel active site with a bound unknown ligand. Thus, activity-centered metagenomics has revealed diverse enzymes and novel families of microbial carboxylesterases, whose activity could not have been predicted using bioinformatics tools. PMID:28272521

  4. Revealing physical interaction networks from statistics of collective dynamics

    PubMed Central

    Nitzan, Mor; Casadiego, Jose; Timme, Marc

    2017-01-01

    Revealing physical interactions in complex systems from observed collective dynamics constitutes a fundamental inverse problem in science. Current reconstruction methods require access to a system’s model or dynamical data at a level of detail often not available. We exploit changes in invariant measures, in particular distributions of sampled states of the system in response to driving signals, and use compressed sensing to reveal physical interaction networks. Dynamical observations following driving suffice to infer physical connectivity even if they are temporally disordered, are acquired at large sampling intervals, and stem from different experiments. Testing various nonlinear dynamic processes emerging on artificial and real network topologies indicates high reconstruction quality for existence as well as type of interactions. These results advance our ability to reveal physical interaction networks in complex synthetic and natural systems. PMID:28246630

  5. Primary Splenic Angiosarcoma Revealed by Bone Marrow Metastasis

    PubMed Central

    Anoun, Soumaya; Marouane, Sofia; Quessar, Asmae; Benchekroun, Said

    2014-01-01

    Primary splenic angiosarcomas are the most common malignant non-hematopoietic tumors of the spleen. Metastatic diseases were found in 69% of patients in a reported series but the incidence of bone marrow involvement is unclear. We report a rare case of a 25-years-old Moroccan woman with unsuspected primary splenic angiosarcoma revealed by bone marrow metastasis. She presented with serious anemia and splenomegaly. Bone marrow biopsy revealed proliferating spindle cells. Computed tomography scanning showed an enlarged spleen with heterogeneous lesions. Splenectomy was performed and retrospective histological study of the spleen confirmed the diagnosis. She died 1 year after splenectomy. PMID:25541659

  6. Primary splenic angiosarcoma revealed by bone marrow metastasis.

    PubMed

    Anoun, Soumaya; Marouane, Sofia; Quessar, Asmae; Benchekroun, Said

    2014-12-05

    Primary splenic angiosarcomas are the most common malignant non-hematopoietic tumors of the spleen. Metastatic diseases were found in 69% of patients in a reported series but the incidence of bone marrow involvement is unclear. We report a rare case of a 25-years-old Moroccan woman with unsuspected primary splenic angiosarcoma revealed by bone marrow metastasis. She presented with serious anemia and splenomegaly. Bone marrow biopsy revealed proliferating spindle cells. Computed tomography scanning showed an enlarged spleen with heterogeneous lesions. Splenectomy was performed and retrospective histological study of the spleen confirmed the diagnosis. She died 1 year after splenectomy.

  7. Wigner flow reveals topological order in quantum phase space dynamics.

    PubMed

    Steuernagel, Ole; Kakofengitis, Dimitris; Ritter, Georg

    2013-01-18

    The behavior of classical mechanical systems is characterized by their phase portraits, the collections of their trajectories. Heisenberg's uncertainty principle precludes the existence of sharply defined trajectories, which is why traditionally only the time evolution of wave functions is studied in quantum dynamics. These studies are quite insensitive to the underlying structure of quantum phase space dynamics. We identify the flow that is the quantum analog of classical particle flow along phase portrait lines. It reveals hidden features of quantum dynamics and extra complexity. Being constrained by conserved flow winding numbers, it also reveals fundamental topological order in quantum dynamics that has so far gone unnoticed.

  8. Puzzles in modern biology. I. Male sterility, failure reveals design.

    PubMed

    Frank, Steven A

    2016-01-01

    Many human males produce dysfunctional sperm. Various plants frequently abort pollen. Hybrid matings often produce sterile males. Widespread male sterility is puzzling. Natural selection prunes reproductive failure. Puzzling failure implies something that we do not understand about how organisms are designed. Solving the puzzle reveals the hidden processes of design.

  9. Adaptation to High Ethanol Reveals Complex Evolutionary Pathways

    PubMed Central

    Das, Anupam; Espinosa-Cantú, Adriana; De Maeyer, Dries; Arslan, Ahmed; Van Pee, Michiel; van der Zande, Elisa; Meert, Wim; Yang, Yudi; Zhu, Bo; Marchal, Kathleen; DeLuna, Alexander; Van Noort, Vera; Jelier, Rob; Verstrepen, Kevin J.

    2015-01-01

    Tolerance to high levels of ethanol is an ecologically and industrially relevant phenotype of microbes, but the molecular mechanisms underlying this complex trait remain largely unknown. Here, we use long-term experimental evolution of isogenic yeast populations of different initial ploidy to study adaptation to increasing levels of ethanol. Whole-genome sequencing of more than 30 evolved populations and over 100 adapted clones isolated throughout this two-year evolution experiment revealed how a complex interplay of de novo single nucleotide mutations, copy number variation, ploidy changes, mutator phenotypes, and clonal interference led to a significant increase in ethanol tolerance. Although the specific mutations differ between different evolved lineages, application of a novel computational pipeline, PheNetic, revealed that many mutations target functional modules involved in stress response, cell cycle regulation, DNA repair and respiration. Measuring the fitness effects of selected mutations introduced in non-evolved ethanol-sensitive cells revealed several adaptive mutations that had previously not been implicated in ethanol tolerance, including mutations in PRT1, VPS70 and MEX67. Interestingly, variation in VPS70 was recently identified as a QTL for ethanol tolerance in an industrial bio-ethanol strain. Taken together, our results show how, in contrast to adaptation to some other stresses, adaptation to a continuous complex and severe stress involves interplay of different evolutionary mechanisms. In addition, our study reveals functional modules involved in ethanol resistance and identifies several mutations that could help to improve the ethanol tolerance of industrial yeasts. PMID:26545090

  10. 24. Demolitin of Pier G reveals the center bays at ...

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

    24. Demolitin of Pier G reveals the center bays at the track well in transverse section. Note structural system of first, second, and third floors, as well as the monitor roof. - Lehigh Valley Railroad, Pier G, Jersey City, Hudson County, NJ

  11. Chemical milling solution reveals stress corrosion cracks in titanium alloy

    NASA Technical Reports Server (NTRS)

    Braski, D. N.

    1967-01-01

    Solution of hydrogen flouride, hydrogen peroxide, and water reveals hot salt stress corrosion cracks in various titanium alloys. After the surface is rinsed in water, dried, and swabbed with the solution, it can be observed by the naked eye or at low magnification.

  12. Revealing the Effects of Cognitive Education Programmes through Dynamic Assessment

    ERIC Educational Resources Information Center

    Tzuriel, David

    2011-01-01

    The major objective of this paper is to demonstrate the effectiveness of dynamic assessment (DA) in revealing outcomes of cognitive education programmes. Three programmes based on "mediated learning experience" theory are reviewed: "Feuerstein's Instrumental Enrichment", "Bright Start", and "Peer Mediation with…

  13. Puzzles in modern biology. I. Male sterility, failure reveals design

    PubMed Central

    Frank, Steven A.

    2016-01-01

    Many human males produce dysfunctional sperm. Various plants frequently abort pollen. Hybrid matings often produce sterile males. Widespread male sterility is puzzling. Natural selection prunes reproductive failure. Puzzling failure implies something that we do not understand about how organisms are designed. Solving the puzzle reveals the hidden processes of design. PMID:28004842

  14. When Values and Behaviors Conflict: Immigrant BSW Students' Experiences Revealed

    ERIC Educational Resources Information Center

    Calderwood, Kimberly; Harper, Kim; Ball, Kellie; Liang, David

    2009-01-01

    This qualitative study reveals the discomfort seven immigrant bachelor of social work students reported experiencing when the behaviors expected of them as Canadian social workers conflicted with their fundamental family values. Behaviorally, participants had assimilated to Canadian and to social work cultures; however, the values they held from…

  15. Integrated genomics of Mucorales reveals novel therapeutic targets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mucormycosis is a life-threatening infection caused by Mucorales fungi. We sequenced 30 fungal genomes and performed transcriptomics with three representative Rhizopus and Mucor strains with human airway epithelial cells during fungal invasion to reveal key host and fungal determinants contributing ...

  16. Fundamental Patterns Underlying Neurotoxicity Revealed by DNA Microarray Expression Profiling

    DTIC Science & Technology

    2004-09-01

    microarray analysis of the dopaminergic cell line, SN4741 , revealed induction of stress indices following MPP* treatment (Chun et al., 2001). To...response to a wide range of cellular stresses including oxidative insult of the nigral dopaminergic cell line SN4741 with hydrogen peroxide or MPP* (Salinas

  17. Detail of south granite pier revealing riveted truss ends and ...

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

    Detail of south granite pier revealing riveted truss ends and iron footing plates on top of granite cap stones. View north - New York, New Haven & Hartford Railroad, Fort Point Channel Rolling Lift Bridge, Spanning Fort Point Channel, Boston, Suffolk County, MA

  18. Experimentally implementable criteria revealing substructures of genuine multipartite entanglement

    SciTech Connect

    Huber, Marcus; Schimpf, Hans; Gabriel, Andreas; Spengler, Christoph; Bruss, Dagmar; Hiesmayr, Beatrix C.

    2011-02-15

    We present a general framework that reveals substructures of genuine multipartite entanglement. Via simple inequalities it is possible to discriminate different sets of multipartite qubit states. These inequalities are beneficial regarding experimental examinations as only local measurements are required. Furthermore, the number of observables scales favorably with system size. In exemplary cases we demonstrate the noise resistance and discuss implementations.

  19. Paraneoplastic opsoclonus-myoclonus-ataxia syndrome revealing dual malignancy.

    PubMed

    Nasri, A; Kacem, I; Jerdak, F; Djebara, M Ben; Mejri, N; Sidhom, Y; Gargouri, A; Gouider, Riadh

    2016-10-01

    Dual malignancy has been rarely associated to paraneoplastic syndromes. We describe an unusual case of metachronous small cell lung carcinoma revealed by opsoclonus-myoclonus ataxia syndrome in a 69-year-old patient with known prostate adenocarcinoma, with positive anti-Hu and anti-Yo antibodies and good responsiveness to corticosteroids and chemotherapy.

  20. The Basics of How to Reveal Epilepsy--Part Two

    ERIC Educational Resources Information Center

    Mittan, Robert J.

    2009-01-01

    In the April 2009 edition of "Exceptional Parent," Part One of this series explored why, for their own emotional well-being, it is so important for parents to tell others about their or their child's epilepsy. This month's installment will discuss the basics of how to reveal epilepsy to others, including some additional advantages one receives in…

  1. Natural Disasters that Reveal Cracks in Our Social Foundation

    ERIC Educational Resources Information Center

    Langer, Nieli

    2004-01-01

    The recent deaths of more than 13,000 French elderly in the European heat wave of 2003 revealed cracks in the social foundation of urban communities, here and abroad. The breakdown occurred in community services, neighborhood networks, and governmental agencies that were responsible for warning of impending dangers to at-risk elderly. This paper…

  2. Thrombotic Microangiopathy Revealing Bone Metastases from an Ethmoid Sinus Carcinoma

    PubMed Central

    Morisse, Mony Chenda; Kontar, Loay; Bihan, Céline; Boone, Mathieu; Lachaier, Emma; Titeca-Beauport, Dimitri; Maizel, Julien; Chauffert, Bruno

    2016-01-01

    Cancer-related thrombotic microangiopathy (TMA) is a rare entity whose clinical and biological characteristics have been described in various tumors. Here we describe the first case of cancer-related TMA revealing diffuse bone metastases from an ethmoid sinus carcinoma. PMID:27721770

  3. Cassini Flybys Reveal Details About Titan Seas and Lakes

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2013-12-01

    The Cassini spacecraft's flybys of Saturn's moon Titan reveal new details about the sizes, depths, and locations of the seas and lakes, whose liquid is mostly methane, that dot the moon's northern hemisphere, according to findings presented by scientists at a 12 December news briefing at the AGU Fall Meeting in San Francisco, Calif.

  4. Perspective view. Fivestory reinforced concrete factory building reveals the structural ...

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

    Perspective view. Five-story reinforced concrete factory building reveals the structural frame on the exterior of the facade. Twelve bay facade facing onto Clay Avenue (north facade) has first floor openings bricked up. Mix of typical factory windows and glass block windows fill the majority of the openings on the rest of building - Russell Industrial Center, 1600 Clay Avenue, Detroit, MI

  5. On the correlation between the structure of lyotropic carriers and the delivery profiles of two common NSAIDs.

    PubMed

    Cohen-Avrahami, Marganit; Shames, Alexander I; Ottaviani, M Francesca; Aserin, Abraham; Garti, Nissim

    2014-10-01

    Two non-steroidal anti-inflammatory drugs (NSAIDs), sodium diclofenac (Na-DFC) and celecoxib (CLXB) were solubilized within cubic and lamellar mesophases as carriers for transdermal drug delivery. SD-NMR, SAXS, ATR-FTIR, and EPR measurements were performed to examine the systems' characteristics and the interactions between the drugs and their hosting mesophases. The amphiphilic drug Na-DFC was found to incorporate at the interfaces of the cubic and lamellar mesophases and thus to act as a cosurfactant and a "structure stabilizer". It increased the order degree and the interactions between the GMO molecules and led the systems toward denser packing. CLXB exhibits an opposite effect on the mesophases. Its solubilization within both systems is accompanied with significant channel swelling and decrease in the order degree. The hydrophobic, rigid and bulky CLXB behaves as a "structure breaker", incorporated between the GMO tails, disturbing the mesophase packing and enhancing the repulsion at the tails region, limiting their close binding. Release experiments from Franz cells revealed that Na-DFC release is dependent on the quantity of water within the hosting mesophase as the water-rich formulation exhibits 1.5-fold enhancement in the release of the drug, compared to the lamellar phase. In contrast, CLXB release was not influenced by the water quantity, hinting that the release mechanisms of the drugs are different while Na-DFC diffuses from the water channels to the external phase, CLXB diffusion occurs through the continuous lipophilic region. The difference in the solubilization sites and interactions of each drug with the mesophases affect their release profiles and determine the preferred formulations for each drug's delivery vehicle.

  6. Benign Cystic Peritoneal Mesothelioma Revealed by Small Bowel Obstruction

    PubMed Central

    Bray Madoué, Kaimba; Boniface, Moifo; Annick Laure, Edzimbi; Pierre, Herve

    2016-01-01

    Benign cystic peritoneal mesothelioma is a rare tumor which frequently occurs in women of reproductive age. Abdominal pain associated with pelvic or abdominal mass is the common clinical presentation. We report the case of a 22-year-old woman with a pathological proved benign cystic mesothelioma of the peritoneum revealed by a small bowel obstruction and a painful left-sided pelvic mass with signs of psoitis. Contrast enhanced abdominal CT-scan demonstrated a large pelvic cystic mass with mass effect on rectosigmoid and pelvic organs. The patient underwent surgical removal of the tumor. Pathological examination revealed the diagnosis of benign cystic mesothelioma of the peritoneum. The outcome was excellent with a 12-month recoil. PMID:27066288

  7. Acting without seeing: eye movements reveal visual processing without awareness.

    PubMed

    Spering, Miriam; Carrasco, Marisa

    2015-04-01

    Visual perception and eye movements are considered to be tightly linked. Diverse fields, ranging from developmental psychology to computer science, utilize eye tracking to measure visual perception. However, this prevailing view has been challenged by recent behavioral studies. Here, we review converging evidence revealing dissociations between the contents of perceptual awareness and different types of eye movement. Such dissociations reveal situations in which eye movements are sensitive to particular visual features that fail to modulate perceptual reports. We also discuss neurophysiological, neuroimaging, and clinical studies supporting the role of subcortical pathways for visual processing without awareness. Our review links awareness to perceptual-eye movement dissociations and furthers our understanding of the brain pathways underlying vision and movement with and without awareness.

  8. Sequencing of Seven Haloarchaeal Genomes Reveals Patterns of Genomic Flux

    PubMed Central

    Lynch, Erin A.; Langille, Morgan G. I.; Darling, Aaron; Wilbanks, Elizabeth G.; Haltiner, Caitlin; Shao, Katie S. Y.; Starr, Michael O.; Teiling, Clotilde; Harkins, Timothy T.; Edwards, Robert A.; Eisen, Jonathan A.; Facciotti, Marc T.

    2012-01-01

    We report the sequencing of seven genomes from two haloarchaeal genera, Haloferax and Haloarcula. Ease of cultivation and the existence of well-developed genetic and biochemical tools for several diverse haloarchaeal species make haloarchaea a model group for the study of archaeal biology. The unique physiological properties of these organisms also make them good candidates for novel enzyme discovery for biotechnological applications. Seven genomes were sequenced to ∼20×coverage and assembled to an average of 50 contigs (range 5 scaffolds - 168 contigs). Comparisons of protein-coding gene compliments revealed large-scale differences in COG functional group enrichment between these genera. Analysis of genes encoding machinery for DNA metabolism reveals genera-specific expansions of the general transcription factor TATA binding protein as well as a history of extensive duplication and horizontal transfer of the proliferating cell nuclear antigen. Insights gained from this study emphasize the importance of haloarchaea for investigation of archaeal biology. PMID:22848480

  9. Mitogenome revealed multiple postdomestication genetic mixtures of West African sheep.

    PubMed

    Brahi, O H D; Xiang, H; Chen, X; Farougou, S; Zhao, X

    2015-10-01

    Notable diversity observed within African ovine breeds makes them of great interests, but limited studies on genetic origins and domestications remain poorly understood. Here, we investigate the evolutionary status of West African native breeds, Djallonke and Sahelian sheep using mitogenome sequencing. Compared with other ovine mitogenome sequences, West African sheep were revealed a Eurasian origin, and the initially tamed sheep breeds in West Africa have been genetically mixed with each other and mixed with European breeds. Worldwide domestic sheep is deemed the Eurasian origin and migrated west to Europe and Africa and east to the Far East, in which dispersed and received selection for acclimation to autochthonic environment independently and ultimately evolved into different native breeds, respectively. Our results contribute to the comprehensive understanding of the domestic sheep origin and reveal multiple postdomestication genetic amelioration processes.

  10. Maps of random walks on complex networks reveal community structure.

    PubMed

    Rosvall, Martin; Bergstrom, Carl T

    2008-01-29

    To comprehend the multipartite organization of large-scale biological and social systems, we introduce an information theoretic approach that reveals community structure in weighted and directed networks. We use the probability flow of random walks on a network as a proxy for information flows in the real system and decompose the network into modules by compressing a description of the probability flow. The result is a map that both simplifies and highlights the regularities in the structure and their relationships. We illustrate the method by making a map of scientific communication as captured in the citation patterns of >6,000 journals. We discover a multicentric organization with fields that vary dramatically in size and degree of integration into the network of science. Along the backbone of the network-including physics, chemistry, molecular biology, and medicine-information flows bidirectionally, but the map reveals a directional pattern of citation from the applied fields to the basic sciences.

  11. Drosophila models reveal novel insights into mechanisms underlying neurodegeneration

    PubMed Central

    Mohan, Ryan D; Workman, Jerry L; Abmayr, Susan M

    2014-01-01

    The SAGA chromatin modifying complex functions as a transcriptional coactivator for a large number of genes, and SAGA dysfunction has been linked to carcinogenesis and neurodegenerative disease. The protein complex is comprised of approximately 20 subunits, arranged in a modular fashion, and includes 2 enzymatic subunits: the Gcn5 acetyltransferase and the Non-stop deubiquitinase. As we learn more about SAGA, it becomes evident that this complex functions through sophisticated mechanisms that support very precise regulation of gene expression. Here we describe recent findings in which a Drosophila loss-of-function model revealed novel mechanisms for regulation of SAGA-mediated histone H2B deubiquitination. This model also yielded novel and surprising insights into mechanisms that underlie progressive neurodegenerative disease. Lastly, we comment on the utility of Drosophila as a model for neurodegenerative disease through which crucial and conserved mechanisms may be revealed. PMID:25483136

  12. Direct visualization reveals kinetics of meiotic chromosome synapsis

    SciTech Connect

    Rog, Ofer; Dernburg, Abby  F.

    2015-03-17

    The synaptonemal complex (SC) is a conserved protein complex that stabilizes interactions along homologous chromosomes (homologs) during meiosis. The SC regulates genetic exchanges between homologs, thereby enabling reductional division and the production of haploid gametes. Here, we directly observe SC assembly (synapsis) by optimizing methods for long-term fluorescence recording in C. elegans. We report that synapsis initiates independently on each chromosome pair at or near pairing centers—specialized regions required for homolog associations. Once initiated, the SC extends rapidly and mostly irreversibly to chromosome ends. Quantitation of SC initiation frequencies and extension rates reveals that initiation is a rate-limiting step in homolog interactions. Eliminating the dynein-driven chromosome movements that accompany synapsis severely retards SC extension, revealing a new role for these conserved motions. This work provides the first opportunity to directly observe and quantify key aspects of meiotic chromosome interactions and will enable future in vivo analysis of germline processes.

  13. Revealing bismuth oxide hollow nanoparticle formation by the Kirkendall effect.

    PubMed

    Niu, Kai-Yang; Park, Jungwon; Zheng, Haimei; Alivisatos, A Paul

    2013-01-01

    We study the formation of bismuth oxide hollow nanoparticles by the Kirkendall effect using liquid cell transmission electron microscopy (TEM). Rich dynamics of bismuth diffusion through the bismuth oxide shell have been captured in situ. The diffusion coefficient of bismuth through bismuth oxide shell is 3-4 orders of magnitude higher than that of bulk. Observation reveals that defects, temperature, sizes of the particles, and so forth can affect the diffusion of reactive species and modify the kinetics of the hollowing process.

  14. Parascapular mass revealing primary tuberculosis of the posterior arch

    PubMed Central

    Arbault, Anais; Ornetti, Paul; Chevallier, Olivier; Avril, Julien; Pottecher, Pierre

    2016-01-01

    We report the case of a parascapular abscess revealing primary tuberculosis of the posterior arch in a 31-year-old man. Sectional imaging is essential in order to detect the different lesions of this atypical spinal tuberculosis as osteolysis of the posterior arch extendible to vertebral body, osteocondensation, epidural extension which is common in this location, and high specificity of a zygapophysial, costo-vertebral or transverse arthritis. PMID:27709081

  15. Placental Abruption Revealed by Hemoperitoneum: A Case Report

    PubMed Central

    Bertholdt, C.; Vincent-Rohfritsch, A.; Tsatsaris, V.; Goffinet, F.

    2016-01-01

    Background Hemoperitoneum is a life-threatening surgical emergency. Diagnosis of the cause is often difficult, in particular, during pregnancy when it may be either obstetric or nonobstetric. Case We report the case of a hemoperitoneum caused by the backflow of blood through a uterine tube, due to placental abruption. Conclusion Hemoperitoneum in pregnant women with no other signs can reveal placental abruption. The difficulty in identifying the cause may delay appropriate management. PMID:27994944

  16. Dermatomyositis revealing breast cancer: report of a case.

    PubMed

    Lamquami, Safae; Errarhay, Sanae; Mamouni, Nisrine; Bouchikhi, Chahrazad; Banani, Abdelaziz

    2015-01-01

    Dermatomyositis (DM) is a rare connective corresponding to an inflammatory disease of skeletal muscles. Paraneoplastic origin must always be sought, primarily gynecological tumor in women, but the investigations are often made difficult by the fact that a primary tumor is often not detectable at the time of the cutaneous manifestations. This approach includes in addition to the monitoring report at regular intervals of 6 to 12 months for two years after diagnosis. We report a case of Dermatomyositis revealing breast cancer.

  17. Spectral Imaging for Revealing and Preserving World Cultural Heritage

    DTIC Science & Technology

    2011-09-01

    of appearance of the original woodcut features Other signal processing included a PCA spectral separation of an iron gall ink inscription most...likely added by Schöner, 1451 as shown in Figure 3. The image processing clearly illus- trates the iron gall ink writing on top of the printing ink ...Figure 3 – PCA of printing and iron gall ink inscription (sheet 10) Other obscured historical information included revealing the text of a

  18. Revealing Companions to Nearby Stars with Astrometric Acceleration

    DTIC Science & Technology

    2012-07-01

    of 57 stars, we compare the statistics of resolved astrometric companions with those of a simulated binary population. The fraction of resolved...frequency of supernovae, blue stragglers, X-ray binaries, etc. The statistical properties of binaries strongly depend on stellar mass. Only for nearby solar ...a large fraction of these stars by the Geneva-Copenhagen Sur- vey of the Solar neighborhood, GCS (Nordströem et al. 2004), revealing short-period

  19. [Neonatal adrenal hemorrhage revealed by jaundice: a case report].

    PubMed

    Oulmaati, A; Hays, S; Mory-Thomas, N; Bretones, P; Bensaid, M; Jordan, I; Bonfils, M; Godbert, I; Picaud, J-C

    2012-04-01

    The clinical presentation of adrenal hemorrhage varies, depending on the extent of hemorrhage as well as the amount of adrenal cortex involved by the hemorrhage. We report here a case of neonatal adrenal hemorrhage revealed by late onset of neonatal jaundice. This adrenal hemorrhage most probably resulted from shoulder dystocia. The aim of this work was to focus on the fact that jaundice can be caused by adrenal hemorrhage and to emphasize the crucial importance of abdominal ultrasound in cases of persistent jaundice.

  20. Revealing topological superconductivity in extended quantum spin Hall Josephson junctions.

    PubMed

    Lee, Shu-Ping; Michaeli, Karen; Alicea, Jason; Yacoby, Amir

    2014-11-07

    Quantum spin Hall-superconductor hybrids are promising sources of topological superconductivity and Majorana modes, particularly given recent progress on HgTe and InAs/GaSb. We propose a new method of revealing topological superconductivity in extended quantum spin Hall Josephson junctions supporting "fractional Josephson currents." Specifically, we show that as one threads magnetic flux between the superconductors, the critical current traces an interference pattern featuring sharp fingerprints of topological superconductivity-even when noise spoils parity conservation.

  1. [Chicken pox recurrence revealing a renal adenocarcinoma in an adult].

    PubMed

    Thieulent, N; Grezard, P; Wolf, F; Barrut, D; Perrot, H

    2000-09-01

    A new episode of chicken pox in adults who had a well documented infection previously is usually observed in immunocompromised individuals. The principal immunodeficiency factors are hematology diseases, acquired immunodeficiency disease and old age. We report here the case of a young woman who after a contaminating contact presented a recurrence of typical chicken pox. Morphological investigations evidenced a right kidney tumor which pathology revealed to be a renal adenocarcinoma. We discuss this pathological association and review cases reported in the literature.

  2. Using metabarcoding to reveal and quantify plant-pollinator interactions

    PubMed Central

    Pornon, André; Escaravage, Nathalie; Burrus, Monique; Holota, Hélène; Khimoun, Aurélie; Mariette, Jérome; Pellizzari, Charlène; Iribar, Amaia; Etienne, Roselyne; Taberlet, Pierre; Vidal, Marie; Winterton, Peter; Zinger, Lucie; Andalo, Christophe

    2016-01-01

    Given the ongoing decline of both pollinators and plants, it is crucial to implement effective methods to describe complex pollination networks across time and space in a comprehensive and high-throughput way. Here we tested if metabarcoding may circumvent the limits of conventional methodologies in detecting and quantifying plant-pollinator interactions. Metabarcoding experiments on pollen DNA mixtures described a positive relationship between the amounts of DNA from focal species and the number of trnL and ITS1 sequences yielded. The study of pollen loads of insects captured in plant communities revealed that as compared to the observation of visits, metabarcoding revealed 2.5 times more plant species involved in plant-pollinator interactions. We further observed a tight positive relationship between the pollen-carrying capacities of insect taxa and the number of trnL and ITS1 sequences. The number of visits received per plant species also positively correlated to the number of their ITS1 and trnL sequences in insect pollen loads. By revealing interactions hard to observe otherwise, metabarcoding significantly enlarges the spatiotemporal observation window of pollination interactions. By providing new qualitative and quantitative information, metabarcoding holds great promise for investigating diverse facets of interactions and will provide a new perception of pollination networks as a whole. PMID:27255732

  3. Tal1 transgenic expression reveals absence of B lymphocytes.

    PubMed

    Palamarchuk, Alexey; Zanesi, Nicola; Aqeilan, Rami I; Efanov, Alexey; Maximov, Vadim; Santanam, Urmila; Hagan, John P; Croce, Carlo M; Pekarsky, Yuri

    2006-06-15

    TAL1 oncogene encodes a helix-loop-helix transcription factor, Tal1, which is required for blood cell development, and its activation is a frequent event in T-cell acute lymphoblastic leukemia. Tal1 interacts and inhibits other helix-loop-helix factors such as E47 and HEB. To investigate the function of Tal1 in B cells, we generated Emu-TAL1 transgenic mouse line, expressing Tal1 in mouse B-cell lineage. Fluorescence-activated cell sorting (FACS) analysis of lymphocytes isolated from spleens of five out of five founders reveals complete absence of IgM- or CD19-expressing cells. Only 2% to 3% of these cells were B220+ and 100% of B220+ cells were CD43+, indicating that these mice were able to make pro-B cells. Similarly, FACS analysis of bone marrow cells in Emu-TAL1 mice revealed complete absence of B220+IgM+ and B220+CD19+ cells. Analysis of the recombination status of IgH genes revealed the presence of D-J but absence or drastic reduction of V-D-J rearrangements. Our results suggest that Tal1 overexpression in B cells results in a phenotype similar to that of B cells of E47/E2A knockout animals. This represents first in vivo evidence that Tal1 can completely inhibit E47/E2A function.

  4. Transient light-induced intracellular oxidation revealed by redox biosensor

    SciTech Connect

    Kolossov, Vladimir L.; Beaudoin, Jessica N.; Hanafin, William P.; DiLiberto, Stephen J.; Kenis, Paul J.A.; Rex Gaskins, H.

    2013-10-04

    Highlights: •Time-resolved live cell imaging revealed light-induced oxidation. •Only the roGFP probe fused with glutaredoxin reveals photooxidation. •The transient oxidation is rapidly reduced by the cytosolic antioxidant system. •Intracellular photooxidation is media-dependent. •Oxidation is triggered exclusively by exposure to short wavelength excitation. -- Abstract: We have implemented a ratiometric, genetically encoded redox-sensitive green fluorescent protein fused to human glutaredoxin (Grx1-roGFP2) to monitor real time intracellular glutathione redox potentials of mammalian cells. This probe enabled detection of media-dependent oxidation of the cytosol triggered by short wavelength excitation. The transient nature of light-induced oxidation was revealed by time-lapse live cell imaging when time intervals of less than 30 s were implemented. In contrast, transient ROS generation was not observed with the parental roGFP2 probe without Grx1, which exhibits slower thiol-disulfide exchange. These data demonstrate that the enhanced sensitivity of the Grx1-roGFP2 fusion protein enables the detection of short-lived ROS in living cells. The superior sensitivity of Grx1-roGFP2, however, also enhances responsiveness to environmental cues introducing a greater likelihood of false positive results during image acquisition.

  5. Traumatic extradural haematoma revealed after contralateral decompressive craniectomy.

    PubMed

    Nadig, Adarsh S; King, Andrew T

    2012-12-01

    Traumatic extradural haematoma following a severe head injury is well documented in neurosurgical literature. We report a case of traumatic extradural haematoma which initially was concealed by the high intracranial pressure (ICP) and revealed after the contralateral decompressive craniectomy. A 21-year-old roofer sustained severe head injury from a fall. The CT brain showed right sided fronto-temporal contusions with small acute subdural haematoma and left orbital roof fracture extending into the temporal bone. ICP was above 45 mmHg even after maximal medical therapy. Decompressive craniectomy was performed on the right side along with contusionectomy. Within an hour, ICP spiked and the CT brain showed left side extradural haematoma. The second surgery demonstrated a bleeding middle meningeal artery associated with the left temporal bone fracture. The clinical sequence of events, radiological and operative findings revealed this to be a traumatic extradural haematoma sustained at the initial trauma. This was revealed after the tamponade effect was released from the initial decompressive craniectomy on the contralateral side.

  6. Active medulloblastoma enhancers reveal subgroup-specific cellular origins.

    PubMed

    Lin, Charles Y; Erkek, Serap; Tong, Yiai; Yin, Linlin; Federation, Alexander J; Zapatka, Marc; Haldipur, Parthiv; Kawauchi, Daisuke; Risch, Thomas; Warnatz, Hans-Jörg; Worst, Barbara C; Ju, Bensheng; Orr, Brent A; Zeid, Rhamy; Polaski, Donald R; Segura-Wang, Maia; Waszak, Sebastian M; Jones, David T W; Kool, Marcel; Hovestadt, Volker; Buchhalter, Ivo; Sieber, Laura; Johann, Pascal; Chavez, Lukas; Gröschel, Stefan; Ryzhova, Marina; Korshunov, Andrey; Chen, Wenbiao; Chizhikov, Victor V; Millen, Kathleen J; Amstislavskiy, Vyacheslav; Lehrach, Hans; Yaspo, Marie-Laure; Eils, Roland; Lichter, Peter; Korbel, Jan O; Pfister, Stefan M; Bradner, James E; Northcott, Paul A

    2016-02-04

    Medulloblastoma is a highly malignant paediatric brain tumour, often inflicting devastating consequences on the developing child. Genomic studies have revealed four distinct molecular subgroups with divergent biology and clinical behaviour. An understanding of the regulatory circuitry governing the transcriptional landscapes of medulloblastoma subgroups, and how this relates to their respective developmental origins, is lacking. Here, using H3K27ac and BRD4 chromatin immunoprecipitation followed by sequencing (ChIP-seq) coupled with tissue-matched DNA methylation and transcriptome data, we describe the active cis-regulatory landscape across 28 primary medulloblastoma specimens. Analysis of differentially regulated enhancers and super-enhancers reinforced inter-subgroup heterogeneity and revealed novel, clinically relevant insights into medulloblastoma biology. Computational reconstruction of core regulatory circuitry identified a master set of transcription factors, validated by ChIP-seq, that is responsible for subgroup divergence, and implicates candidate cells of origin for Group 4. Our integrated analysis of enhancer elements in a large series of primary tumour samples reveals insights into cis-regulatory architecture, unrecognized dependencies, and cellular origins.

  7. Active medulloblastoma enhancers reveal subgroup-specific cellular origins

    PubMed Central

    Lin, Charles Y.; Erkek, Serap; Tong, Yiai; Yin, Linlin; Federation, Alexander J.; Zapatka, Marc; Haldipur, Parthiv; Kawauchi, Daisuke; Risch, Thomas; Warnatz, Hans-Jörg; Worst, Barbara C.; Ju, Bensheng; Orr, Brent A.; Zeid, Rhamy; Polaski, Donald R.; Segura-Wang, Maia; Waszak, Sebastian M.; Jones, David T.W.; Kool, Marcel; Hovestadt, Volker; Buchhalter, Ivo; Sieber, Laura; Johann, Pascal; Chavez, Lukas; Gröschel, Stefan; Ryzhova, Marina; Korshunov, Andrey; Chen, Wenbiao; Chizhikov, Victor V.; Millen, Kathleen J.; Amstislavskiy, Vyacheslav; Lehrach, Hans; Yaspo, Marie-Laure; Eils, Roland; Lichter, Peter; Korbel, Jan O.; Pfister, Stefan M.; Bradner, James E.; Northcott, Paul A.

    2016-01-01

    Summary Medulloblastoma is a highly malignant paediatric brain tumour, often inflicting devastating consequences on the developing child. Genomic studies have revealed four distinct molecular subgroups with divergent biology and clinical behaviour. An understanding of the regulatory circuitry governing the transcriptional landscapes of medulloblastoma subgroups, and how this relates to their respective developmental origins, is lacking. Using H3K27ac and BRD4 ChIP-Seq, coupled with tissue-matched DNA methylation and transcriptome data, we describe the active cis-regulatory landscape across 28 primary medulloblastoma specimens. Analysis of differentially regulated enhancers and super-enhancers reinforced inter-subgroup heterogeneity and revealed novel, clinically relevant insights into medulloblastoma biology. Computational reconstruction of core regulatory circuitry identified a master set of transcription factors, validated by ChIP-Seq, that are responsible for subgroup divergence and implicate candidate cells-of-origin for Group 4. Our integrated analysis of enhancer elements in a large series of primary tumour samples reveals insights into cis-regulatory architecture, unrecognized dependencies, and cellular origins. PMID:26814967

  8. Using metabarcoding to reveal and quantify plant-pollinator interactions.

    PubMed

    Pornon, André; Escaravage, Nathalie; Burrus, Monique; Holota, Hélène; Khimoun, Aurélie; Mariette, Jérome; Pellizzari, Charlène; Iribar, Amaia; Etienne, Roselyne; Taberlet, Pierre; Vidal, Marie; Winterton, Peter; Zinger, Lucie; Andalo, Christophe

    2016-06-03

    Given the ongoing decline of both pollinators and plants, it is crucial to implement effective methods to describe complex pollination networks across time and space in a comprehensive and high-throughput way. Here we tested if metabarcoding may circumvent the limits of conventional methodologies in detecting and quantifying plant-pollinator interactions. Metabarcoding experiments on pollen DNA mixtures described a positive relationship between the amounts of DNA from focal species and the number of trnL and ITS1 sequences yielded. The study of pollen loads of insects captured in plant communities revealed that as compared to the observation of visits, metabarcoding revealed 2.5 times more plant species involved in plant-pollinator interactions. We further observed a tight positive relationship between the pollen-carrying capacities of insect taxa and the number of trnL and ITS1 sequences. The number of visits received per plant species also positively correlated to the number of their ITS1 and trnL sequences in insect pollen loads. By revealing interactions hard to observe otherwise, metabarcoding significantly enlarges the spatiotemporal observation window of pollination interactions. By providing new qualitative and quantitative information, metabarcoding holds great promise for investigating diverse facets of interactions and will provide a new perception of pollination networks as a whole.

  9. Interior Evolution of Ceres and Vesta Revealed by Dawn

    NASA Astrophysics Data System (ADS)

    Raymond, C. A.; Russell, C. T.; Bland, M. T.; Castillo, J. C.; De Sanctis, M. C.; Ermakov, A.; Jaumann, R.; Konopliv, A. S.; Marchi, S.; McCord, T. B.; McSween, H. Y., Jr.; Nathues, A.; Park, R. S.; Prettyman, T. H.; Toplis, M. J.; Zuber, M. T.

    2015-12-01

    Dawn's exploration of Vesta and Ceres has revealed their geophysical characteristics, informing the processes that shaped the bodies. Dawn has determined the average diameter of Ceres to be 940 km, smaller than the previously estimated 975 km [1]. This implies a density of 2160 kg/m3, indicating that Ceres is less differentiated than predicted [2]. Ceres' entire surface is cratered, implying the lack of a thick (10's of km) water ice layer at the surface. Variability in Ceres' crater morphology indicates that the near-surface layer has variable strength and rheology, likely due to heterogeneity in the near-surface mixture of rock, ice and salt. These observations may indicate that Ceres lost a significant amount of an original surface ice layer due to impact erosion. The lack of large impact basins on Ceres can be interpreted to be the result of viscous relaxation. These data provide insights into Ceres' thermal evolution and mechanical properties, which appear to be unique to this warm, icy body. In contrast to Ceres, Vesta formed very early and hot, resulting in a fully differentiated body. Dawn's exploration revealed geophysical and geochemical evidence for an iron-rich core and basaltic crust. However, unlike the pre-Dawn paradigm of Vesta's evolution, Dawn found that the crust and mantle of Vesta are less distinct than predicted by classical differentiation models. [1] Thomas, P. C., et al., Differentiation of the asteroid Ceres as revealed by its shape, Nature, 437, 224-226, 2005; [2] McCord et al., Ceres: Its Origin, Evolution and Structure and Dawn's Potential Contribution, Space Sci Rev
DOI 10.1007/s11214-010-9729-9, 2011.

  10. Genes but Not Genomes Reveal Bacterial Domestication of Lactococcus Lactis

    PubMed Central

    Passerini, Delphine; Beltramo, Charlotte; Coddeville, Michele; Quentin, Yves; Ritzenthaler, Paul

    2010-01-01

    Background The population structure and diversity of Lactococcus lactis subsp. lactis, a major industrial bacterium involved in milk fermentation, was determined at both gene and genome level. Seventy-six lactococcal isolates of various origins were studied by different genotyping methods and thirty-six strains displaying unique macrorestriction fingerprints were analyzed by a new multilocus sequence typing (MLST) scheme. This gene-based analysis was compared to genomic characteristics determined by pulsed-field gel electrophoresis (PFGE). Methodology/Principal Findings The MLST analysis revealed that L. lactis subsp. lactis is essentially clonal with infrequent intra- and intergenic recombination; also, despite its taxonomical classification as a subspecies, it displays a genetic diversity as substantial as that within several other bacterial species. Genome-based analysis revealed a genome size variability of 20%, a value typical of bacteria inhabiting different ecological niches, and that suggests a large pan-genome for this subspecies. However, the genomic characteristics (macrorestriction pattern, genome or chromosome size, plasmid content) did not correlate to the MLST-based phylogeny, with strains from the same sequence type (ST) differing by up to 230 kb in genome size. Conclusion/Significance The gene-based phylogeny was not fully consistent with the traditional classification into dairy and non-dairy strains but supported a new classification based on ecological separation between “environmental” strains, the main contributors to the genetic diversity within the subspecies, and “domesticated” strains, subject to recent genetic bottlenecks. Comparison between gene- and genome-based analyses revealed little relationship between core and dispensable genome phylogenies, indicating that clonal diversification and phenotypic variability of the “domesticated” strains essentially arose through substantial genomic flux within the dispensable genome

  11. Estimating the probability of failure when testing reveals no failures

    NASA Technical Reports Server (NTRS)

    Miller, Keith W.; Morell, Larry J.; Noonan, Robert E.; Park, Stephen K.; Nicol, David M.; Murrill, Branson W.; Voas, Jeffrey M.

    1992-01-01

    Formulas for estimating the probability of failure when testing reveals no errors are introduced. These formulas incorporate random testing results, information about the input distribution, and prior assumptions about the probability of failure of the software. The formulas are not restricted to equally likely input distributions, and the probability of failure estimate can be adjusted when assumptions about the input distribution change. The formulas are based on a discrete sample space statistical model of software and include Bayesian prior assumptions. Reusable software and software in life-critical applications are particularly appropriate candidates for this type of analysis.

  12. Cutaneous metastasis revealing a relapse of gastric linitis: Another case

    PubMed Central

    Kairouani, Mouna; Perrin, Julie; Dietemann-Barabinot, Anne; Diab, Rafiq; Ruck, Stephane

    2012-01-01

    INTRODUCTION Cutaneous metastasis from gastric cancer is a rare occurrence. The linitis gastric carcinoma accounts only 8.7% of all gastric cancers. PRESENTATION OF CASE We report a case of female patient who was followed for linits cancer with peritoneal metastasis treated by six cycles of chemotherapy. After seventeen months of control, the relapse of the disease revealed by occurrence of cutaneous metastatsis. DISCUSSION Cutaneous metastasis from linit gastric is rare and the prognostic remains poor. The treatment is palliative. CONCLUSION This rare presentation should encourage the practitioners to biopsy any suspicion skin lesion. PMID:23276763

  13. Mediated amperometry reveals different modes of yeast responses to sugars.

    PubMed

    Garjonyte, Rasa; Melvydas, Vytautas; Malinauskas, Albertas

    2016-02-01

    Menadione-mediated amperometry at carbon paste electrodes modified with various yeasts (Saccharomyces cerevisiae, Candida pulcherrima, Pichia guilliermondii and Debaryomyces hansenii) was employed to monitor redox activity inside the yeast cells induced by glucose, fructose, sucrose, maltose or galactose. Continuous measurements revealed distinct modes (transient or gradually increasing) of the current development during the first 2 to 3 min after subjection to glucose, fructose and sucrose at electrodes containing S. cerevisiae and non-Saccharomyces strains. Different modes (increasing or decreasing) of the current development after yeast subjection to galactose at electrodes with S. cerevisiae or D. hansenii and at electrodes with C. pulcherrima and P. guilliermondii suggested different mechanisms of galactose assimilation.

  14. How the ``Blues'' reveals the intimacy of music and physics

    NASA Astrophysics Data System (ADS)

    Gibson, J. Murray

    2013-03-01

    Little do most people know when they hear blues piano - and you'll hear some live in this talk - that physics permeates the style, as it does all of music. Why should you care? By deconstructing blues piano the intimacy of physics, mathematics and music will be revealed in its glory.[1] The exercise says something about how the brains of the music composer and of the listener must be intimately linked to the physical principles of acoustics. And it provides a great vehicle to explain physical phenomena to non-scientists - everything from quantum mechanics to protein structure.

  15. Protein tagging reveals new insights into signaling in flagella.

    PubMed

    Ishikawa, Takashi

    2014-03-03

    In this issue, Oda et al. (2014. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201312014) use mutant analysis, protein tagging, and cryoelectron tomography to determine the detailed location of components in flagellar radial spokes-a complex of proteins that connect the peripheral microtubule doublets to the central pair. Remarkably, this approach revealed an interaction between radial spokes and the central pair based on geometry rather than a specific signaling mechanism, highlighting the importance of studying a system in three dimensions.

  16. Tributaries of West Antarctic Ice Streams Revealed by RADARSAT Interferometry.

    PubMed

    Joughin; Gray; Bindschadler; Price; Morse; Hulbe; Mattar; Werner

    1999-10-08

    Interferometric RADARSAT data are used to map ice motion in the source areas of four West Antarctic ice streams. The data reveal that tributaries, coincident with subglacial valleys, provide a spatially extensive transition between slow inland flow and rapid ice stream flow and that adjacent ice streams draw from shared source regions. Two tributaries flow into the stagnant ice stream C, creating an extensive region that is thickening at an average rate of 0.49 meters per year. This is one of the largest rates of thickening ever reported in Antarctica.

  17. Invoking Thomas Kuhn: What Citation Analysis Reveals about Science Education

    NASA Astrophysics Data System (ADS)

    Loving, Cathleen C.; Cobern, William W.

    This paper analyzes how Thomas Kuhn's writings are used by others, especially science education researchers. Previous research in citation analysis is used to frame questions related to who cites Kuhn, in what manner and why. Research questions first focus on the variety of disciplines invoking Kuhn and to what extent Structure of Scientific Revolutions (SSR) is cited. The Web of Science database provides material from 1982 for this analysis. The science education literature is analyzed using back issues from 1985 of the Journal of Research in Science Teaching and Science Education. An article analysis reveals trends in terms of what Kuhnian ideas are most frequently invoked. Results indicate a wide array of disciplines from beekeeping to law cite Kuhn - especially generic citations to SSR. The science education journal analysis reveals pervasive use of the term paradigm, although use is quite varied. The two areas of research in science education most impacted by Kuhn appear to be conceptual change theory and constructivist epistemologies. Additional uses of Kuhn are discussed. The degree to which Kuhn is invoked in ways supporting the theoretical framework of citation analysis, whether his work is misappropriated, and the impact of Kuhn are discussed.

  18. The Microbiome of Brazilian Mangrove Sediments as Revealed by Metagenomics

    PubMed Central

    Andreote, Fernando Dini; Jiménez, Diego Javier; Chaves, Diego; Dias, Armando Cavalcante Franco; Luvizotto, Danice Mazzer; Dini-Andreote, Francisco; Fasanella, Cristiane Cipola; Lopez, Maryeimy Varon; Baena, Sandra; Taketani, Rodrigo Gouvêa; de Melo, Itamar Soares

    2012-01-01

    Here we embark in a deep metagenomic survey that revealed the taxonomic and potential metabolic pathways aspects of mangrove sediment microbiology. The extraction of DNA from sediment samples and the direct application of pyrosequencing resulted in approximately 215 Mb of data from four distinct mangrove areas (BrMgv01 to 04) in Brazil. The taxonomic approaches applied revealed the dominance of Deltaproteobacteria and Gammaproteobacteria in the samples. Paired statistical analysis showed higher proportions of specific taxonomic groups in each dataset. The metabolic reconstruction indicated the possible occurrence of processes modulated by the prevailing conditions found in mangrove sediments. In terms of carbon cycling, the sequences indicated the prevalence of genes involved in the metabolism of methane, formaldehyde, and carbon dioxide. With respect to the nitrogen cycle, evidence for sequences associated with dissimilatory reduction of nitrate, nitrogen immobilization, and denitrification was detected. Sequences related to the production of adenylsulfate, sulfite, and H2S were relevant to the sulphur cycle. These data indicate that the microbial core involved in methane, nitrogen, and sulphur metabolism consists mainly of Burkholderiaceae, Planctomycetaceae, Rhodobacteraceae, and Desulfobacteraceae. Comparison of our data to datasets from soil and sea samples resulted in the allotment of the mangrove sediments between those samples. The results of this study add valuable data about the composition of microbial communities in mangroves and also shed light on possible transformations promoted by microbial organisms in mangrove sediments. PMID:22737213

  19. Computational modeling reveals molecular details of epidermal growth factor binding

    PubMed Central

    Mayawala, Kapil; Vlachos, Dionisios G; Edwards, Jeremy S

    2005-01-01

    Background The ErbB family of receptors are dysregulated in a number of cancers, and the signaling pathway of this receptor family is a critical target for several anti-cancer drugs. Therefore a detailed understanding of the mechanisms of receptor activation is critical. However, despite a plethora of biochemical studies and recent single particle tracking experiments, the early molecular mechanisms involving epidermal growth factor (EGF) binding and EGF receptor (EGFR) dimerization are not as well understood. Herein, we describe a spatially distributed Monte Carlo based simulation framework to enable the simulation of in vivo receptor diffusion and dimerization. Results Our simulation results are in agreement with the data from single particle tracking and biochemical experiments on EGFR. Furthermore, the simulations reveal that the sequence of receptor-receptor and ligand-receptor reaction events depends on the ligand concentration, receptor density and receptor mobility. Conclusion Our computer simulations reveal the mechanism of EGF binding on EGFR. Overall, we show that spatial simulation of receptor dynamics can be used to gain a mechanistic understanding of receptor activation which may in turn enable improved cancer treatments in the future. PMID:16318625

  20. Microsatellite genotyping reveals a signature in breast cancer exomes.

    PubMed

    McIver, L J; Fonville, N C; Karunasena, E; Garner, H R

    2014-06-01

    Genomic instability at microsatellite loci is a hallmark of many cancers, including breast cancer. However, much of the genomic variation and many of the hereditary components responsible for breast cancer remain undetected. We hypothesized that variation at microsatellites could provide additional genomic markers for breast cancer risk assessment. A total of 1,345 germline and tumor DNA samples from individuals diagnosed with breast cancer, exome sequenced as part of The Cancer Genome Atlas, were analyzed for microsatellite variation. The comparison group for our analysis, representing healthy individuals, consisted of 249 females which were exome sequenced as part of the 1,000 Genomes Project. We applied our microsatellite-based genotyping pipeline to identify 55 microsatellite loci that can distinguish between the germline of individuals diagnosed with breast cancer and healthy individuals with a sensitivity of 88.4 % and a specificity of 77.1 %. Further, we identified additional microsatellite loci that are potentially useful for distinguishing between breast cancer subtypes, revealing a possible fifth subtype. These findings are of clinical interest as possible risk diagnostics and reveal genes that may be of potential therapeutic value, including genes previously not associated with breast cancer.

  1. Piriform spider silk sequences reveal unique repetitive elements.

    PubMed

    Perry, David J; Bittencourt, Daniela; Siltberg-Liberles, Jessica; Rech, Elibio L; Lewis, Randolph V

    2010-11-08

    Orb-weaving spider silk fibers are assembled from very large, highly repetitive proteins. The repeated segments contain, in turn, short, simple, and repetitive amino acid motifs that account for the physical and mechanical properties of the assembled fiber. Of the six orb-weaver silk fibroins, the piriform silk that makes the attachment discs, which lashes the joints of the web and attaches dragline silk to surfaces, has not been previously characterized. Piriform silk protein cDNAs were isolated from phage libraries of three species: A. trifasciata , N. clavipes , and N. cruentata . The deduced amino acid sequences from these genes revealed two new repetitive motifs: an alternating proline motif, where every other amino acid is proline, and a glutamine-rich motif of 6-8 amino acids. Similar to other spider silk proteins, the repeated segments are large (>200 amino acids) and highly homogenized within a species. There is also substantial sequence similarity across the genes from the three species, with particular conservation of the repetitive motifs. Northern blot analysis revealed that the mRNA is larger than 11 kb and is expressed exclusively in the piriform glands of the spider. Phylogenetic analysis of the C-terminal regions of the new proteins with published spidroins robustly shows that the piriform sequences form an ortholog group.

  2. Blue whale earplug reveals lifetime contaminant exposure and hormone profiles.

    PubMed

    Trumble, Stephen J; Robinson, Eleanor M; Berman-Kowalewski, Michelle; Potter, Charles W; Usenko, Sascha

    2013-10-15

    Lifetime contaminant and hormonal profiles have been reconstructed for an individual male blue whale (Balaenoptera musculus, Linnaeus 1758) using the earplug as a natural aging matrix that is also capable of archiving and preserving lipophilic compounds. These unprecedented lifetime profiles (i.e., birth to death) were reconstructed with a 6-mo resolution for a wide range of analytes including cortisol (stress hormone), testosterone (developmental hormone), organic contaminants (e.g., pesticides and flame retardants), and mercury. Cortisol lifetime profiles revealed a doubling of cortisol levels over baseline. Testosterone profiles suggest this male blue whale reached sexual maturity at approximately 10 y of age, which corresponds well with and improves on previous estimates. Early periods of the reconstructed contaminant profiles for pesticides (such as dichlorodiphenyltrichloroethanes and chlordanes), polychlorinated biphenyls, and polybrominated diphenyl ethers demonstrate significant maternal transfer occurred at 0-12 mo. The total lifetime organic contaminant burden measured between the earplug (sum of contaminants in laminae layers) and blubber samples from the same organism were similar. Total mercury profiles revealed reduced maternal transfer and two distinct pulse events compared with organic contaminants. The use of a whale earplug to reconstruct lifetime chemical profiles will allow for a more comprehensive examination of stress, development, and contaminant exposure, as well as improve the assessment of contaminant use/emission, environmental noise, ship traffic, and climate change on these important marine sentinels.

  3. Membrane protein properties revealed through data-rich electrostatics calculations

    PubMed Central

    Guerriero, Christopher J.; Brodsky, Jeffrey L.; Grabe, Michael

    2015-01-01

    SUMMARY The electrostatic properties of membrane proteins often reveal many of their key biophysical characteristics, such as ion channel selectivity and the stability of charged membrane-spanning segments. The Poisson-Boltzmann (PB) equation is the gold standard for calculating protein electrostatics, and the software APBSmem enables the solution of the PB equation in the presence of a membrane. Here, we describe significant advances to APBSmem including: full automation of system setup, per-residue energy decomposition, incorporation of PDB2PQR, calculation of membrane induced pKa shifts, calculation of non-polar energies, and command-line scripting for large scale calculations. We highlight these new features with calculations carried out on a number of membrane proteins, including the recently solved structure of the ion channel TRPV1 and a large survey of 1,614 membrane proteins of known structure. This survey provides a comprehensive list of residues with large electrostatic penalties for being embedded in the membrane potentially revealing interesting functional information. PMID:26118532

  4. Reticulated lipid probe fluorescence reveals MDCK cell apical membrane topography.

    PubMed

    Colarusso, Pina; Spring, Kenneth R

    2002-02-01

    High spatial resolution confocal microscopy of young MDCK cells stained with the lipophilic probe 1,1'-dihexadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate (DiIC(16)) revealed a reticulated fluorescence pattern on the apical membrane. DiIC(16) was delivered as crystals to live cells to minimize possible solvent perturbations of the membrane lipids. The ratio of the integrated fluorescence intensities in the bright versus dim regions was 1.6 +/- 0.1 (n = 13). Deconvolved images of the cells were consistent with exclusive plasma membrane staining. Multi-spectral and fluorescence anisotropy microscopy did not reveal differences between bright and dim regions. Bright regions coincided with microvilli and microridges observed by differential interference contrast microscopy and were stable for several minutes. Fluorescence recovery after photobleaching yielded similar diffusion coefficients (pooled D = 1.5 +/- 0.6 x 10(-9) cm(2)/s, n = 40) for both bright and dim regions. Line fluorescence recovery after photobleaching showed that the reticulated pattern was maintained as the fluorescence recovered in the bleached areas. Cytochalasin D did not affect the staining pattern, but the pattern was eliminated by cholesterol depletion with methyl-beta-cyclodextrin. We conclude that the reticulated fluorescence pattern was caused by increased optical path lengths through the microvilli and microridges compared with the flat areas on the apical membrane.

  5. Reticulated lipid probe fluorescence reveals MDCK cell apical membrane topography.

    PubMed Central

    Colarusso, Pina; Spring, Kenneth R

    2002-01-01

    High spatial resolution confocal microscopy of young MDCK cells stained with the lipophilic probe 1,1'-dihexadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate (DiIC(16)) revealed a reticulated fluorescence pattern on the apical membrane. DiIC(16) was delivered as crystals to live cells to minimize possible solvent perturbations of the membrane lipids. The ratio of the integrated fluorescence intensities in the bright versus dim regions was 1.6 +/- 0.1 (n = 13). Deconvolved images of the cells were consistent with exclusive plasma membrane staining. Multi-spectral and fluorescence anisotropy microscopy did not reveal differences between bright and dim regions. Bright regions coincided with microvilli and microridges observed by differential interference contrast microscopy and were stable for several minutes. Fluorescence recovery after photobleaching yielded similar diffusion coefficients (pooled D = 1.5 +/- 0.6 x 10(-9) cm(2)/s, n = 40) for both bright and dim regions. Line fluorescence recovery after photobleaching showed that the reticulated pattern was maintained as the fluorescence recovered in the bleached areas. Cytochalasin D did not affect the staining pattern, but the pattern was eliminated by cholesterol depletion with methyl-beta-cyclodextrin. We conclude that the reticulated fluorescence pattern was caused by increased optical path lengths through the microvilli and microridges compared with the flat areas on the apical membrane. PMID:11806917

  6. Blue whale earplug reveals lifetime contaminant exposure and hormone profiles

    PubMed Central

    Trumble, Stephen J.; Robinson, Eleanor M.; Berman-Kowalewski, Michelle; Potter, Charles W.; Usenko, Sascha

    2013-01-01

    Lifetime contaminant and hormonal profiles have been reconstructed for an individual male blue whale (Balaenoptera musculus, Linnaeus 1758) using the earplug as a natural aging matrix that is also capable of archiving and preserving lipophilic compounds. These unprecedented lifetime profiles (i.e., birth to death) were reconstructed with a 6-mo resolution for a wide range of analytes including cortisol (stress hormone), testosterone (developmental hormone), organic contaminants (e.g., pesticides and flame retardants), and mercury. Cortisol lifetime profiles revealed a doubling of cortisol levels over baseline. Testosterone profiles suggest this male blue whale reached sexual maturity at approximately 10 y of age, which corresponds well with and improves on previous estimates. Early periods of the reconstructed contaminant profiles for pesticides (such as dichlorodiphenyltrichloroethanes and chlordanes), polychlorinated biphenyls, and polybrominated diphenyl ethers demonstrate significant maternal transfer occurred at 0–12 mo. The total lifetime organic contaminant burden measured between the earplug (sum of contaminants in laminae layers) and blubber samples from the same organism were similar. Total mercury profiles revealed reduced maternal transfer and two distinct pulse events compared with organic contaminants. The use of a whale earplug to reconstruct lifetime chemical profiles will allow for a more comprehensive examination of stress, development, and contaminant exposure, as well as improve the assessment of contaminant use/emission, environmental noise, ship traffic, and climate change on these important marine sentinels. PMID:24043814

  7. Genome Sequencing Reveals a Phage in Helicobacter pylori

    PubMed Central

    Lehours, Philippe; Vale, Filipa F.; Bjursell, Magnus K.; Melefors, Ojar; Advani, Reza; Glavas, Steve; Guegueniat, Julia; Gontier, Etienne; Lacomme, Sabrina; Alves Matos, António; Menard, Armelle; Mégraud, Francis; Engstrand, Lars; Andersson, Anders F.

    2011-01-01

    ABSTRACT Helicobacter pylori chronically infects the gastric mucosa in more than half of the human population; in a subset of this population, its presence is associated with development of severe disease, such as gastric cancer. Genomic analysis of several strains has revealed an extensive H. pylori pan-genome, likely to grow as more genomes are sampled. Here we describe the draft genome sequence (63 contigs; 26× mean coverage) of H. pylori strain B45, isolated from a patient with gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The major finding was a 24.6-kb prophage integrated in the bacterial genome. The prophage shares most of its genes (22/27) with prophage region II of Helicobacter acinonychis strain Sheeba. After UV treatment of liquid cultures, circular DNA carrying the prophage integrase gene could be detected, and intracellular tailed phage-like particles were observed in H. pylori cells by transmission electron microscopy, indicating that phage production can be induced from the prophage. PCR amplification and sequencing of the integrase gene from 341 H. pylori strains from different geographic regions revealed a high prevalence of the prophage (21.4%). Phylogenetic reconstruction showed four distinct clusters in the integrase gene, three of which tended to be specific for geographic regions. Our study implies that phages may play important roles in the ecology and evolution of H. pylori. PMID:22086490

  8. Previously Unrecognized Large Lunar Impact Basins Revealed by Topographic Data

    NASA Technical Reports Server (NTRS)

    Frey, Herbert V.

    2008-01-01

    The discovery of a large population of apparently buried impact craters on Mars, revealed as Quasi- Circular Depressions (QCDs) in Mars Orbiting Laser Altimeter (MOLA) data [1,2,3] and as Circular Thin Areas (CTAs) [4] in crustal thickness model data [5] leads to the obvious question: are there unrecognized impact features on the Moon and other bodies in the solar system? Early analysis of Clementine topography revealed several large impact basins not previously known [6,7], so the answer certainly is "Yes." How large a population of previously undetected impact basins, their size frequency distribution, and how much these added craters and basins will change ideas about the early cratering history and Late Heavy Bombardment on the Moon remains to be determined. Lunar Orbiter Laser Altimeter (LOLA) data [8] will be able to address these issues. As a prelude, we searched the state-of-the-art global topographic grid for the Moon, the Unified Lunar Control Net (ULCN) [9] for evidence of large impact features not previously recognized by photogeologic mapping, as summarized by Wilhelms [lo].

  9. Proteomics Reveals Novel Drosophila Seminal Fluid Proteins Transferred at Mating

    PubMed Central

    Findlay, Geoffrey D; Yi, Xianhua; MacCoss, Michael J; Swanson, Willie J

    2008-01-01

    Across diverse taxa, seminal fluid proteins (Sfps) transferred at mating affect the reproductive success of both sexes. Such reproductive proteins often evolve under positive selection between species; because of this rapid divergence, Sfps are hypothesized to play a role in speciation by contributing to reproductive isolation between populations. In Drosophila, individual Sfps have been characterized and are known to alter male sperm competitive ability and female post-mating behavior, but a proteomic-scale view of the transferred Sfps has been missing. Here we describe a novel proteomic method that uses whole-organism isotopic labeling to detect transferred Sfps in mated female D. melanogaster. We identified 63 proteins, which were previously unknown to function in reproduction, and confirmed the transfer of dozens of predicted Sfps. Relative quantification of protein abundance revealed that several of these novel Sfps are abundant in seminal fluid. Positive selection and tandem gene duplication are the prevailing forces of Sfp evolution, and comparative proteomics with additional species revealed lineage-specific changes in seminal fluid content. We also report a proteomic-based gene discovery method that uncovered 19 previously unannotated genes in D. melanogaster. Our results demonstrate an experimental method to identify transferred proteins in any system that is amenable to isotopic labeling, and they underscore the power of combining proteomic and evolutionary analyses to shed light on the complex process of Drosophila reproduction. PMID:18666829

  10. Memory in motion: movement dynamics reveal memory strength.

    PubMed

    Papesh, Megan H; Goldinger, Stephen D

    2012-10-01

    Recognition memory is typically examined as a discrete end-state, describable by static variables, such as accuracy, response time, and confidence. In the present study, we combined real-time mouse-tracking with subsequent, overt confidence estimates to examine the dynamic nature of memory decisions. By examining participants' streaming x-, y- mouse coordinates during recognition decisions, we observed that movement trajectories revealed underlying response confidence. More confident decisions were associated with shorter decision times and more linear response trajectories. Less confident decisions were made slowly, with increased trajectory curvature. Statistical indices of curvature and decision times, including area-under-the-curve and time to maximum deviation, suggested that memory strength relates to response dynamics. Whether participants were correct or incorrect, old responses showed a stronger correspondence between mouse trajectories and confidence, relative to new responses. We suggest that people subjectively experience a correspondence between feelings of memory and feelings of confidence; that subjective experience reveals itself in real-time decision processes, as suggested by sequential sampling models of recognition decisions.

  11. Economic choices reveal probability distortion in macaque monkeys.

    PubMed

    Stauffer, William R; Lak, Armin; Bossaerts, Peter; Schultz, Wolfram

    2015-02-18

    Economic choices are largely determined by two principal elements, reward value (utility) and probability. Although nonlinear utility functions have been acknowledged for centuries, nonlinear probability weighting (probability distortion) was only recently recognized as a ubiquitous aspect of real-world choice behavior. Even when outcome probabilities are known and acknowledged, human decision makers often overweight low probability outcomes and underweight high probability outcomes. Whereas recent studies measured utility functions and their corresponding neural correlates in monkeys, it is not known whether monkeys distort probability in a manner similar to humans. Therefore, we investigated economic choices in macaque monkeys for evidence of probability distortion. We trained two monkeys to predict reward from probabilistic gambles with constant outcome values (0.5 ml or nothing). The probability of winning was conveyed using explicit visual cues (sector stimuli). Choices between the gambles revealed that the monkeys used the explicit probability information to make meaningful decisions. Using these cues, we measured probability distortion from choices between the gambles and safe rewards. Parametric modeling of the choices revealed classic probability weighting functions with inverted-S shape. Therefore, the animals overweighted low probability rewards and underweighted high probability rewards. Empirical investigation of the behavior verified that the choices were best explained by a combination of nonlinear value and nonlinear probability distortion. Together, these results suggest that probability distortion may reflect evolutionarily preserved neuronal processing.

  12. Direct visualization reveals kinetics of meiotic chromosome synapsis

    DOE PAGES

    Rog, Ofer; Dernburg, Abby  F.

    2015-03-17

    The synaptonemal complex (SC) is a conserved protein complex that stabilizes interactions along homologous chromosomes (homologs) during meiosis. The SC regulates genetic exchanges between homologs, thereby enabling reductional division and the production of haploid gametes. Here, we directly observe SC assembly (synapsis) by optimizing methods for long-term fluorescence recording in C. elegans. We report that synapsis initiates independently on each chromosome pair at or near pairing centers—specialized regions required for homolog associations. Once initiated, the SC extends rapidly and mostly irreversibly to chromosome ends. Quantitation of SC initiation frequencies and extension rates reveals that initiation is a rate-limiting step inmore » homolog interactions. Eliminating the dynein-driven chromosome movements that accompany synapsis severely retards SC extension, revealing a new role for these conserved motions. This work provides the first opportunity to directly observe and quantify key aspects of meiotic chromosome interactions and will enable future in vivo analysis of germline processes.« less

  13. Circadian acetylome reveals regulation of mitochondrial metabolic pathways.

    PubMed

    Masri, Selma; Patel, Vishal R; Eckel-Mahan, Kristin L; Peleg, Shahaf; Forne, Ignasi; Ladurner, Andreas G; Baldi, Pierre; Imhof, Axel; Sassone-Corsi, Paolo

    2013-02-26

    The circadian clock is constituted by a complex molecular network that integrates a number of regulatory cues needed to maintain organismal homeostasis. To this effect, posttranslational modifications of clock proteins modulate circadian rhythms and are thought to convert physiological signals into changes in protein regulatory function. To explore reversible lysine acetylation that is dependent on the clock, we have characterized the circadian acetylome in WT and Clock-deficient (Clock(-/-)) mouse liver by quantitative mass spectrometry. Our analysis revealed that a number of mitochondrial proteins involved in metabolic pathways are heavily influenced by clock-driven acetylation. Pathways such as glycolysis/gluconeogenesis, citric acid cycle, amino acid metabolism, and fatty acid metabolism were found to be highly enriched hits. The significant number of metabolic pathways whose protein acetylation profile is altered in Clock(-/-) mice prompted us to link the acetylome to the circadian metabolome previously characterized in our laboratory. Changes in enzyme acetylation over the circadian cycle and the link to metabolite levels are discussed, revealing biological implications connecting the circadian clock to cellular metabolic state.

  14. Revealing quantum correlation by negativity of the Wigner function

    NASA Astrophysics Data System (ADS)

    Taghiabadi, Razieh; Akhtarshenas, Seyed Javad; Sarbishaei, Mohsen

    2016-05-01

    We analyze two two-mode continuous variable separable states with the same marginal states. We adopt the definition of classicality in the form of well-defined positive Wigner function describing the state and find that although the states possess positive local Wigner functions, they exhibit negative Wigner functions for the global states. Using the negativity of Wigner function as an indicator of nonclassicality, we show that despite these states possess different negativities of the Wigner function, they do not reveal this difference as phase space nonclassicalities such as negativity of the Mandel Q parameter or quadrature squeezing. We then concentrate on quantum correlation of these states and show that quantum discord and local quantum uncertainty, as two well-defined measures of quantum correlation, manifest the difference between negativity of the Wigner functions. The non-Gaussianity of these states is also examined and show that the difference in behavior of their non-Gaussianity is the same as the difference between negativity of their Wigner functions. We also investigate the influence of correlation rank criterion and find that when the states can be produced locally from classical states, the Wigner functions cannot reveal their quantum correlations.

  15. Anticipatory eye fixations reveal tool knowledge for tool interaction.

    PubMed

    Belardinelli, Anna; Barabas, Marissa; Himmelbach, Marc; Butz, Martin V

    2016-08-01

    Action-oriented eye-tracking studies have shown that eye fixations reveal much about current behavioral intentions. The eyes typically fixate those positions of a tool or an object where the fingers will be placed next, or those positions in a scene, where obstacles need to be avoided to successfully reach or transport a tool or object. Here, we asked to what extent eye fixations can also reveal active cognitive inference processes, which are expected to integrate bottom-up visual information with internal knowledge for planning suitable object interactions task-dependently. In accordance to the available literature, we expected that task-relevant knowledge will include sensorimotor, semantic, and mechanical aspects. To investigate if and in which way this internal knowledge influences eye fixation behavior while planning an object interaction, we presented pictures of familiar and unfamiliar tools and instructed participants to either pantomime 'lifting' or 'using' the respective tool. When confronted with unfamiliar tools, participants fixated the tool's effector part closer and longer in comparison with familiar tools. This difference was particularly prominent during 'using' trials when compared with 'lifting' trials. We suggest that this difference indicates that the brain actively extracts mechanical information about the unknown tool in order to infer its appropriate usage. Moreover, the successive fixations over a trial indicate that a dynamic, task-oriented, active cognitive process unfolds, which integrates available tool knowledge with visually gathered information to plan and determine the currently intended tool interaction.

  16. Ancient DNA sequence revealed by error-correcting codes

    PubMed Central

    Brandão, Marcelo M.; Spoladore, Larissa; Faria, Luzinete C. B.; Rocha, Andréa S. L.; Silva-Filho, Marcio C.; Palazzo, Reginaldo

    2015-01-01

    A previously described DNA sequence generator algorithm (DNA-SGA) using error-correcting codes has been employed as a computational tool to address the evolutionary pathway of the genetic code. The code-generated sequence alignment demonstrated that a residue mutation revealed by the code can be found in the same position in sequences of distantly related taxa. Furthermore, the code-generated sequences do not promote amino acid changes in the deviant genomes through codon reassignment. A Bayesian evolutionary analysis of both code-generated and homologous sequences of the Arabidopsis thaliana malate dehydrogenase gene indicates an approximately 1 MYA divergence time from the MDH code-generated sequence node to its paralogous sequences. The DNA-SGA helps to determine the plesiomorphic state of DNA sequences because a single nucleotide alteration often occurs in distantly related taxa and can be found in the alternative codon patterns of noncanonical genetic codes. As a consequence, the algorithm may reveal an earlier stage of the evolution of the standard code. PMID:26159228

  17. Effect of processing pressure on the properties of graphite foam

    NASA Astrophysics Data System (ADS)

    Shah, Raviraj; Soni, Neha; Shrivastava, R.

    2013-06-01

    Graphite foam samples were prepared by heating mesophase pitch at different processing pressures followed by carbonization and graphitization under inert atmosphere. These samples were characterized for density, surface morphology and thermal conductivity. Microstructure of the samples indicate that processing pressure controls the evolution of volatiles from mesophase pitch to create a structure having optimum pore size, ligament thickness and junctions, which all are responsible for physical and thermal properties of resultant graphite foam. The study reveals that there is a relationship between processing pressure and the final density & thermal conductivity.

  18. Bio-based ionic liquid crystalline quaternary ammonium salts: properties and applications.

    PubMed

    Sasi, Renjith; Rao, Talasila P; Devaki, Sudha J

    2014-03-26

    In the present work, we describe the preparation, properties, and applications of novel ionic liquid crystalline quaternary ammonium salts (QSs) of 3-pentadecylphenol, a bio-based low-cost material derived from cashew nut shell liquid. Amphotropic liquid crystalline phase formation in QSs was characterized using a combination of techniques, such as DSC, PLM, XRD, SEM, and rheology, which revealed the formation of one, two, and three dimensionally ordered mesophases in different length scales. On the basis of these results, a plausible mechanism for the formation of specific modes of packing in various mesophases was proposed. Observation of anisotropic ionic conductivity and electrochemical stability suggests their application as a solid electrolyte.

  19. Offenders' crime narratives as revealed by the Narrative Roles Questionnaire.

    PubMed

    Youngs, Donna; Canter, David V

    2013-03-01

    The study of narrative processes as part of the immediate factors that shape criminal action is limited by the lack of a methodology for differentiating the narrative themes that characterise specific crime events. The current study explores how the roles offenders see themselves as playing during an offence encapsulate their underlying crime narratives and thus provide the basis for a quantitative methodology. To test this possibility, a 33-item Narrative Roles Questionnaire (NRQ) was developed from intensive interviews with offenders about their experience of committing a recent offence. A multidimensional analysis of the NRQ completed by 71 convicted offenders revealed life narrative themes similar to those identified in fiction by Frye and with noncriminals by McAdams, labelled The Professional, Victim, Hero, and Revenger offence roles. The NRQ thus is a first step in opening up the possibility of empirical studies of the narrative aetiological perspective in criminology.

  20. [Elderly women: revealing their experiences and care needs].

    PubMed

    Merighi, Miriam Aparecida Barbosa; de Oliveira, Deíse Moura; de Jesus, Maria Cristina Pinto; Souto, Rafaella Queiroga; Thamada, Andressa Akina

    2013-04-01

    This qualitative study used a social phenomenology approach to elucidate the experiences, care needs and expectations of the elderly women. Nine elderly women were interviewed between February and May 2011 using a semi-structured questionnaire. The elderly women referred to their physical, mental, and social limitations. They valued ​​the preservation of their autonomy in daily activities and in self-care and considered their families to be a fundamental support. They had expectations of remaining healthy, pursuing leisure activities, and having improved access to healthcare information and treatment. The absence of prospects at this stage of life was related to the loss of significant people and the loss of health. The results of this study reveal important aspects of the experiences of elderly women and encourage further research and improvement in teaching, clinical practice and management policies in relation to the needs of these women.

  1. Stochastic heart-rate model can reveal pathologic cardiac dynamics

    NASA Astrophysics Data System (ADS)

    Kuusela, Tom

    2004-03-01

    A simple one-dimensional Langevin-type stochastic difference equation can simulate the heart-rate fluctuations in a time scale from minutes to hours. The model consists of a deterministic nonlinear part and a stochastic part typical of Gaussian noise, and both parts can be directly determined from measured heart-rate data. Data from healthy subjects typically exhibit the deterministic part with two or more stable fixed points. Studies of 15 congestive heart-failure subjects reveal that the deterministic part of pathologic heart dynamics has no clear stable fixed points. Direct simulations of the stochastic model for normal and pathologic cases can produce statistical parameters similar to those of real subjects. Results directly indicate that pathologic situations simplify the heart-rate control system.

  2. Mathematical Analysis of Biomolecular Network Reveals Connections Between Diseases

    NASA Astrophysics Data System (ADS)

    Wang, Guanyu

    2012-02-01

    Connections between cancer and metabolic diseases may consist in the complex network of interactions among a common set of biomolecules. By applying singularity and bifurcation analysis, the phenotypes constrained by the AKT signaling pathway are identified and mapped onto the parameter space, which include cancer and certain metabolic diseases. By considering physiologic properties (sensitivity, robustness and adaptivity) the AKT pathway must possess in order to efficiently sense growth factors and nutrients, the region of normal responses is located. The analysis illuminates the parameter space and reveals system-level mechanisms in regulating biological functions (cell growth, survival, proliferation and metabolism) and how their deregulation may lead to the development of diseases. The analytical expressions summarize the synergistic interactions among many molecules, which provides valuable insights into therapeutic interventions.

  3. Heat islands over Mumbai as revealed by autorecorded thermograph data

    NASA Astrophysics Data System (ADS)

    Srivastava, A. K.; Voogt, James; Kshirsagar, S. R.; Srivastava, Kavita

    2016-02-01

    This study examined hourly temperature data of two locations of Mumbai metropolitan city. One data point (Coloba, Mumbai) is in centre of the city and the other one (Santacruz, Mumbai) is at the airport. The study finds that there were many occasions when night-time hourly temperatures over the city centre were considerably higher than that of the airport, even though temperature at the time of sunset at both the places was nearly same. In this study, the occasions, when hourly night-time temperature over city was more than that of the airport by objectively defined threshold value (3.0 ∘C in this study) for most of the hours in the night, were termed as heat island events. Analysis of the study reveals that these events are mostly confined to November-February months. The study also found that frequency of such events has doubled in recent two decades in comparison to the earlier two decades.

  4. Marine and terrestrial ecology: unifying concepts, revealing differences.

    PubMed

    Webb, Thomas J

    2012-10-01

    The extent to which similar ecological processes operate on land and in the sea has been much debated, with apparently 'fundamental' differences often disappearing when appropriate comparisons are made. However, marine and terrestrial ecology have developed as largely separate intellectual endeavours, which has hampered the search for general patterns and mechanisms. Here, I argue that marine-terrestrial comparative studies can be extremely useful at uncovering mechanisms when they explicitly consider those facets of the environment that are important to a particular hypothesis. Furthermore, the binary 'marine-terrestrial' division misses many opportunities for more interesting comparisons, several of which I highlight here. Increasing the flow of concepts, hypotheses, and data between marine and terrestrial ecologists is essential to reveal those differences that really are important.

  5. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    SciTech Connect

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-12-17

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.

  6. The genome of Tetranychus urticae reveals herbivorous pest adaptations

    PubMed Central

    Grbić, Miodrag; Van Leeuwen, Thomas; Clark, Richard M.; Rombauts, Stephane; Rouzé, Pierre; Grbić, Vojislava; Osborne, Edward J.; Dermauw, Wannes; Ngoc, Phuong Cao Thi; Ortego, Félix; Hernández-Crespo, Pedro; Diaz, Isabel; Martinez, Manuel; Navajas, Maria; Sucena, Élio; Magalhães, Sara; Nagy, Lisa; Pace, Ryan M.; Djuranović, Sergej; Smagghe, Guy; Iga, Masatoshi; Christiaens, Olivier; Veenstra, Jan A.; Ewer, John; Villalobos, Rodrigo Mancilla; Hutter, Jeffrey L.; Hudson, Stephen D.; Velez, Marisela; Yi, Soojin V.; Zeng, Jia; Pires-daSilva, Andre; Roch, Fernando; Cazaux, Marc; Navarro, Marie; Zhurov, Vladimir; Acevedo, Gustavo; Bjelica, Anica; Fawcett, Jeffrey A.; Bonnet, Eric; Martens, Cindy; Baele, Guy; Wissler, Lothar; Sanchez-Rodriguez, Aminael; Tirry, Luc; Blais, Catherine; Demeestere, Kristof; Henz, Stefan R.; Gregory, T. Ryan; Mathieu, Johannes; Verdon, Lou; Farinelli, Laurent; Schmutz, Jeremy; Lindquist, Erika; Feyereisen, René; Van de Peer, Yves

    2016-01-01

    The spider mite Tetranychus urticae is a cosmopolitan agricultural pest with an extensive host plant range and an extreme record of pesticide resistance. Here we present the completely sequenced and annotated spider mite genome, representing the first complete chelicerate genome. At 90 megabases T. urticae has the smallest sequenced arthropod genome. Compared with other arthropods, the spider mite genome shows unique changes in the hormonal environment and organization of the Hox complex, and also reveals evolutionary innovation of silk production. We find strong signatures of polyphagy and detoxification in gene families associated with feeding on different hosts and in new gene families acquired by lateral gene transfer. Deep transcriptome analysis of mites feeding on different plants shows how this pest responds to a changing host environment. The T. urticae genome thus offers new insights into arthropod evolution and plant–herbivore interactions, and provides unique opportunities for developing novel plant protection strategies. PMID:22113690

  7. Revealing the Genetic Basis of Natural Bacterial Phenotypic Divergence

    PubMed Central

    Freddolino, Peter L.; Goodarzi, Hani

    2014-01-01

    Divergent phenotypes for distantly related strains of bacteria, such as differing antibiotic resistances or organic solvent tolerances, are of keen interest both from an evolutionary perspective and for the engineering of novel microbial organisms and consortia in synthetic biology applications. A prerequisite for any practical application of this phenotypic diversity is knowledge of the genetic determinants for each trait of interest. Sequence divergence between strains is often so extensive as to make brute-force approaches to identifying the loci contributing to a given trait impractical. Here we describe a global linkage analysis approach, GLINT, for rapid discovery of the causal genetic variants underlying phenotypic divergence between distantly related strains of Escherichia coli. This general strategy will also be usable, with minor modifications, for revealing genotype-phenotype associations between naturally occurring strains of other bacterial species. PMID:24317396

  8. Hybridization Reveals the Evolving Genomic Architecture of Speciation

    PubMed Central

    Kronforst, Marcus R.; Hansen, Matthew E.B.; Crawford, Nicholas G.; Gallant, Jason R.; Zhang, Wei; Kulathinal, Rob J.; Kapan, Durrell D.; Mullen, Sean P.

    2014-01-01

    SUMMARY The rate at which genomes diverge during speciation is unknown, as are the physical dynamics of the process. Here, we compare full genome sequences of 32 butterflies, representing five species from a hybridizing Heliconius butterfly community, to examine genome-wide patterns of introgression and infer how divergence evolves during the speciation process. Our analyses reveal that initial divergence is restricted to a small fraction of the genome, largely clustered around known wing-patterning genes. Over time, divergence evolves rapidly, due primarily to the origin of new divergent regions. Furthermore, divergent genomic regions display signatures of both selection and adaptive introgression, demonstrating the link between microevolutionary processes acting within species and the origin of species across macroevolutionary timescales. Our results provide a uniquely comprehensive portrait of the evolving species boundary due to the role that hybridization plays in reducing the background accumulation of divergence at neutral sites. PMID:24183670

  9. Silk protein aggregation kinetics revealed by Rheo-IR.

    PubMed

    Boulet-Audet, Maxime; Terry, Ann E; Vollrath, Fritz; Holland, Chris

    2014-02-01

    The remarkable mechanical properties of silk fibres stem from a multi-scale hierarchical structure created when an aqueous protein "melt" is converted to an insoluble solid via flow. To directly relate a silk protein's structure and function in response to flow, we present the first application of a Rheo-IR platform, which couples cone and plate rheology with attenuated total reflectance infrared spectroscopy. This technique provides a new window into silk processing by linking shear thinning to an increase in molecular alignment, with shear thickening affecting changes in the silk protein's secondary structure. Additionally, compared to other static characterization methods for silk, Rheo-IR proved particularly useful at revealing the intrinsic difference between natural (native) and reconstituted silk feedstocks. Hence Rheo-IR offers important novel insights into natural silk processing. This has intrinsic academic merit, but it might also be useful when designing reconstituted silk analogues alongside other polymeric systems, whether natural or synthetic.

  10. Chaos in spin glasses revealed through thermal boundary conditions

    NASA Astrophysics Data System (ADS)

    Wang, Wenlong; Machta, Jonathan; Katzgraber, Helmut G.

    2015-09-01

    We study the fragility of spin glasses to small temperature perturbations numerically using population annealing Monte Carlo. We apply thermal boundary conditions to a three-dimensional Edwards-Anderson Ising spin glass. In thermal boundary conditions all eight combinations of periodic versus antiperiodic boundary conditions in the three spatial directions are present, each appearing in the ensemble with its respective statistical weight determined by its free energy. We show that temperature chaos is revealed in the statistics of crossings in the free energy for different boundary conditions. By studying the energy difference between boundary conditions at free-energy crossings, we determine the domain-wall fractal dimension. Similarly, by studying the number of crossings, we determine the chaos exponent. Our results also show that computational hardness in spin glasses and the presence of chaos are closely related.

  11. Multicentric Castleman's Disease in a Child Revealed by Chronic Diarrhea

    PubMed Central

    Benmiloud, Sarra; Chaouki, Sana; Atmani, Samir; Hida, Moustapha

    2015-01-01

    Multicentric Castleman's disease is a rare benign and unexplained lymphoproliferative disorder that is extremely uncommon in children. It presents with fever, systemic symptoms, generalized lymphadenopathy, and laboratory markers of inflammation. Its treatment is not standardized and its prognosis is poor. We report a novel case of multicentric Castleman's disease in a 13-year-old girl who had presented with chronic diarrhea as the only initial presenting symptom. The diagnosis of celiac or inflammatory bowel diseases was suspected, but two and a half years later, the diagnosis of multicentric Castleman's disease was brought following the appearance of abdominal mass whose biopsy revealed Castleman's disease in the plasma cell form. The outcome was favorable after treatment by corticosteroid, chemotherapy, and surgery. The occurrence of diarrhea as the initial symptom of multicentric Castleman's disease without lymph node involvement is very rare. This case report underlines the diagnostic difficulties and the long interval between onset and diagnosis when diarrhea occurs first. PMID:25737793

  12. Hodgkin's Lymphoma Revealed by Hemophagocytic Lymphohistiocytosis in a Child

    PubMed Central

    Benmiloud, Sarra; Hbibi, Mohamed; Chaouki, Sana; Abourazzak, Sana; Hida, Moustapha

    2014-01-01

    Hemophagocytic lymphohistiocytosis (HLH) is a severe life-threatening disorder, responsible for extensive phagocytosis of hematopoietic cells and causing a multisystem organ failure. If lymphomas are common causes of HLH, the association with Hodgkin's lymphoma is rarely described in children. We report a case of a 9-year-old boy presenting with HLH as an initial manifestation of Hodgkin's lymphoma. He has been suffering from persistent high fever, asthenia, weight loss, and hepatosplenomegaly with no lymphadenopathy. The diagnosis of HLH secondary to infectious disease was initially worn. The patient received high-dose intravenous immunoglobulin with broad-spectrum antibiotics. However, his state got worse with the onset of dry cough and pleural effusion. Histopathologic examination of pleural fluid showed the presence of Reed-Sternberg cells. The outcome was favorable after treatment by corticosteroid and chemotherapy. Hodgkin's lymphoma revealed by HLH is a source of delayed diagnosis and should be borne in mind in children. PMID:25328742

  13. Revealing invisible photonic printing: colorful pattern shown by water

    NASA Astrophysics Data System (ADS)

    Chen, C.; Dong, Z. Q.; Chen, Y.; Hu, X. B.; Zhu, X. R.; Zhu, Z. G.; Qian, S. H.; Shih, W. H.

    2017-01-01

    Patterning and displaying of photonic crystals are critical for building advanced photonic materials. We developed a monolayered colloidal crystal (MCC) based photonic material through a mask-assistant photo-polymerization process. Polystyrene (PS) nanoparticles were firstly assembled on the glass slide to form highly ordered MCC, this template is invisible and could diffract visible light when infiltrated by solvent. This reversibly displaying property was successfully maintained after the MCC was surrounding by a polymer layer via photo-polymerization, meanwhile a pattern could also be printed on the polymer with the help of a mask. Such photonic printing could be reversibly shown and hidden, revealing the colorful pattern was mainly due to the non-uniform cross-linking density of the polymer.

  14. Revealing a signaling role of phytosphingosine-1-phosphate in yeast.

    PubMed

    Cowart, L Ashley; Shotwell, Matthew; Worley, Mitchell L; Richards, Adam J; Montefusco, David J; Hannun, Yusuf A; Lu, Xinghua

    2010-01-01

    Sphingolipids including sphingosine-1-phosphate and ceramide participate in numerous cell programs through signaling mechanisms. This class of lipids has important functions in stress responses; however, determining which sphingolipid mediates specific events has remained encumbered by the numerous metabolic interconnections of sphingolipids, such that modulating a specific lipid of interest through manipulating metabolic enzymes causes 'ripple effects', which change levels of many other lipids. Here, we develop a method of integrative analysis for genomic, transcriptomic, and lipidomic data to address this previously intractable problem. This method revealed a specific signaling role for phytosphingosine-1-phosphate, a lipid with no previously defined specific function in yeast, in regulating genes required for mitochondrial respiration through the HAP complex transcription factor. This approach could be applied to extract meaningful biological information from a similar experimental design that produces multiple sets of high-throughput data.

  15. Revealing a signaling role of phytosphingosine-1-phosphate in yeast

    PubMed Central

    Cowart, L Ashley; Shotwell, Matthew; Worley, Mitchell L; Richards, Adam J; Montefusco, David J; Hannun, Yusuf A; Lu, Xinghua

    2010-01-01

    Sphingolipids including sphingosine-1-phosphate and ceramide participate in numerous cell programs through signaling mechanisms. This class of lipids has important functions in stress responses; however, determining which sphingolipid mediates specific events has remained encumbered by the numerous metabolic interconnections of sphingolipids, such that modulating a specific lipid of interest through manipulating metabolic enzymes causes ‘ripple effects', which change levels of many other lipids. Here, we develop a method of integrative analysis for genomic, transcriptomic, and lipidomic data to address this previously intractable problem. This method revealed a specific signaling role for phytosphingosine-1-phosphate, a lipid with no previously defined specific function in yeast, in regulating genes required for mitochondrial respiration through the HAP complex transcription factor. This approach could be applied to extract meaningful biological information from a similar experimental design that produces multiple sets of high-throughput data. PMID:20160710

  16. Dramatic changes in electronic structure revealed by fractionally charged nuclei

    NASA Astrophysics Data System (ADS)

    Cohen, Aron J.; Mori-Sánchez, Paula

    2014-01-01

    Discontinuous changes in the electronic structure upon infinitesimal changes to the Hamiltonian are demonstrated. These are revealed in one and two electron molecular systems by full configuration interaction (FCI) calculations when the realm of the nuclear charge is extended to be fractional. FCI electron densities in these systems show dramatic changes in real space and illustrate the transfer, hopping, and removal of electrons. This is due to the particle nature of electrons seen in stretched systems and is a manifestation of an energy derivative discontinuity at constant number of electrons. Dramatic errors of density functional theory densities are seen in real space as this physics is missing from currently used approximations. The movements of electrons in these simple systems encapsulate those in real physical processes, from chemical reactions to electron transport and pose a great challenge for the development of new electronic structure methods.

  17. Physical Principles of Skeletal Minerals Revealed with Spectromicroscopy

    SciTech Connect

    Gilbert, Pupa

    2009-08-05

    Skeletal elements of marine and terrestrial organisms have the most fascinating nano-to-macro-structures, attracting the attention of physicists, biologists, chemists, and materials scientists. Using X-PEEM spectromicroscopy we revealed some of the fundamental mechanisms leading to the formation of these biominerals. Specifically, we addressed the following questions and provided the answers: 1Q) How do teeth, bones, and echinoderm and mollusk shells acquire their unusual, curved and complex morphology, if they are composed of single crystals? 1A) Via amorphous precursor phases; 2Q) How does crystallinity propagate through the amorophous precursor phases in sea urchin spicules and teeth? 2A) By secondary nucleation, following random walk patterns; 3Q) How does iridescent mother-of-pearl become ordered? 3A) Gradually, through a kinetic mechanisms in which fastest growing single-crystals win the competition for space, thus end up being approximately co-oriented.

  18. Axis Patterning by BMPs: Cnidarian Network Reveals Evolutionary Constraints

    PubMed Central

    Genikhovich, Grigory; Fried, Patrick; Prünster, M. Mandela; Schinko, Johannes B.; Gilles, Anna F.; Fredman, David; Meier, Karin; Iber, Dagmar; Technau, Ulrich

    2015-01-01

    Summary BMP signaling plays a crucial role in the establishment of the dorso-ventral body axis in bilaterally symmetric animals. However, the topologies of the bone morphogenetic protein (BMP) signaling networks vary drastically in different animal groups, raising questions about the evolutionary constraints and evolvability of BMP signaling systems. Using loss-of-function analysis and mathematical modeling, we show that two signaling centers expressing different BMPs and BMP antagonists maintain the secondary axis of the sea anemone Nematostella. We demonstrate that BMP signaling is required for asymmetric Hox gene expression and mesentery formation. Computational analysis reveals that network parameters related to BMP4 and Chordin are constrained both in Nematostella and Xenopus, while those describing the BMP signaling modulators can vary significantly. Notably, only chordin, but not bmp4 expression needs to be spatially restricted for robust signaling gradient formation. Our data provide an explanation of the evolvability of BMP signaling systems in axis formation throughout Eumetazoa. PMID:25772352

  19. Drought-Responsive Mechanisms in Plant Leaves Revealed by Proteomics.

    PubMed

    Wang, Xiaoli; Cai, Xiaofeng; Xu, Chenxi; Wang, Quanhua; Dai, Shaojun

    2016-10-18

    Plant drought tolerance is a complex trait that requires a global view to understand its underlying mechanism. The proteomic aspects of plant drought response have been extensively investigated in model plants, crops and wood plants. In this review, we summarize recent proteomic studies on drought response in leaves to reveal the common and specialized drought-responsive mechanisms in different plants. Although drought-responsive proteins exhibit various patterns depending on plant species, genotypes and stress intensity, proteomic analyses show that dominant changes occurred in sensing and signal transduction, reactive oxygen species scavenging, osmotic regulation, gene expression, protein synthesis/turnover, cell structure modulation, as well as carbohydrate and energy metabolism. In combination with physiological and molecular results, proteomic studies in leaves have helped to discover some potential proteins and/or metabolic pathways for drought tolerance. These findings provide new clues for understanding the molecular basis of plant drought tolerance.

  20. Physical Principles of Skeletal Minerals Revealed with Spectromicroscopy

    ScienceCinema

    Gilbert, Pupa [U of Wisconsin-Madison, Wisconsin, United States

    2016-07-12

    Skeletal elements of marine and terrestrial organisms have the most fascinating nano-to-macro-structures, attracting the attention of physicists, biologists, chemists, and materials scientists. Using X-PEEM spectromicroscopy we revealed some of the fundamental mechanisms leading to the formation of these biominerals. Specifically, we addressed the following questions and provided the answers: 1Q) How do teeth, bones, and echinoderm and mollusk shells acquire their unusual, curved and complex morphology, if they are composed of single crystals? 1A) Via amorphous precursor phases; 2Q) How does crystallinity propagate through the amorophous precursor phases in sea urchin spicules and teeth? 2A) By secondary nucleation, following random walk patterns; 3Q) How does iridescent mother-of-pearl become ordered? 3A) Gradually, through a kinetic mechanisms in which fastest growing single-crystals win the competition for space, thus end up being approximately co-oriented.

  1. Drought-Responsive Mechanisms in Plant Leaves Revealed by Proteomics

    PubMed Central

    Wang, Xiaoli; Cai, Xiaofeng; Xu, Chenxi; Wang, Quanhua; Dai, Shaojun

    2016-01-01

    Plant drought tolerance is a complex trait that requires a global view to understand its underlying mechanism. The proteomic aspects of plant drought response have been extensively investigated in model plants, crops and wood plants. In this review, we summarize recent proteomic studies on drought response in leaves to reveal the common and specialized drought-responsive mechanisms in different plants. Although drought-responsive proteins exhibit various patterns depending on plant species, genotypes and stress intensity, proteomic analyses show that dominant changes occurred in sensing and signal transduction, reactive oxygen species scavenging, osmotic regulation, gene expression, protein synthesis/turnover, cell structure modulation, as well as carbohydrate and energy metabolism. In combination with physiological and molecular results, proteomic studies in leaves have helped to discover some potential proteins and/or metabolic pathways for drought tolerance. These findings provide new clues for understanding the molecular basis of plant drought tolerance. PMID:27763546

  2. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    NASA Astrophysics Data System (ADS)

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-12-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution.

  3. Spring-Block Model Reveals Region-Like Structures

    PubMed Central

    Máté, Gabriell; Néda, Zoltán; Benedek, József

    2011-01-01

    A mechanical spring-block model is used for realizing an objective space partition of settlements from a geographic territory in region-like structures. The method is based on the relaxation-dynamics of the spring-block system and reveals in a hierarchical manner region-like entities at different spatial scales. It takes into account in an elegant manner both the spatiality of the elements and the connectivity relations among them. Spatiality is taken into account by using the geographic coordinates of the settlements, and by detecting the neighbors with the help of a Delaunay triangulation. Connectivity between neighboring settlements are quantified using a Pearson-like correlation for the relative variation of a relevant socio-economic parameter (population size, GDP, tax payed per inhabitant, etc.). The method is implemented in an interactive JAVA application and it is applied with success for an artificially generated society and for the case of USA, Hungary and Transylvania. PMID:21346819

  4. Macrophage characteristics of stem cells revealed by transcriptome profiling

    SciTech Connect

    Charriere, Guillaume M.; Cousin, Beatrice; Arnaud, Emmanuelle; Saillan-Barreau, Corinne; Andre, Mireille; Massoudi, Ali; Dani, Christian; Penicaud, Luc; Casteilla, Louis . E-mail: casteil@toulouse.inserm.fr

    2006-10-15

    We previously showed that the phenotypes of adipocyte progenitors and macrophages were close. Using functional analyses and microarray technology, we first tested whether this intriguing relationship was specific to adipocyte progenitors or could be shared with other progenitors. Measurements of phagocytic activity and gene profiling analysis of different progenitor cells revealed that the latter hypothesis should be retained. These results encouraged us to pursue and to confirm our analysis with a gold-standard stem cell population, embryonic stem cells or ESC. The transcriptomic profiles of ESC and macrophages were clustered together, unlike differentiated ESC. In addition, undifferentiated ESC displayed higher phagocytic activity than other progenitors, and they could phagocytoze apoptotic bodies. These data suggest that progenitors and stem cells share some characteristics of macrophages. This opens new perspectives on understanding stem cell phenotype and functionalities such as a putative role of stem cells in tissue remodeling by discarding dead cells but also their immunomodulation or fusion properties.

  5. ALMA Reveals Internal Structure of Molecular Clouds in the LMC

    NASA Astrophysics Data System (ADS)

    Sawada, T.; Hasegawa, T.; Koda, J.

    2015-12-01

    We carried out high-resolution (0.7 pc) CO J=1-0 mosaic observations of five giant molecular clouds, which cover a wide range of evolutionary stages based on their associations to recent star formation, in the Large Magellanic Cloud with ALMA. The observations revealed a variety of spatial structures of the gas, from faint and diffuse emission to bright and compact structures. The variation of structures, which is similar to that seen in the Milky Way, is quantified by the brightness distribution function (BDF) and brightness distribution index (BDI) established in our prior studies. The structured molecular gas may indicate the readiness for, rather than the outcome of, star formation.

  6. Inheritance Patterns in Citation Networks Reveal Scientific Memes

    NASA Astrophysics Data System (ADS)

    Kuhn, Tobias; Perc, Matjaž; Helbing, Dirk

    2014-10-01

    Memes are the cultural equivalent of genes that spread across human culture by means of imitation. What makes a meme and what distinguishes it from other forms of information, however, is still poorly understood. Our analysis of memes in the scientific literature reveals that they are governed by a surprisingly simple relationship between frequency of occurrence and the degree to which they propagate along the citation graph. We propose a simple formalization of this pattern and validate it with data from close to 50 million publication records from the Web of Science, PubMed Central, and the American Physical Society. Evaluations relying on human annotators, citation network randomizations, and comparisons with several alternative approaches confirm that our formula is accurate and effective, without a dependence on linguistic or ontological knowledge and without the application of arbitrary thresholds or filters.

  7. ID-Check: Online Concealed Information Test Reveals True Identity.

    PubMed

    Verschuere, Bruno; Kleinberg, Bennett

    2016-01-01

    The Internet has already changed people's lives considerably and is likely to drastically change forensic research. We developed a web-based test to reveal concealed autobiographical information. Initial studies identified a number of conditions that affect diagnostic efficiency. By combining these moderators, this study investigated the full potential of the online ID-check. Participants (n = 101) tried to hide their identity and claimed a false identity in a reaction time-based Concealed Information Test. Half of the participants were presented with personal details (e.g., first name, last name, birthday), whereas the others only saw irrelevant details. Results showed that participants' true identity could be detected with high accuracy (AUC = 0.98; overall accuracy: 86-94%). Online memory detection can reliably and validly detect whether someone is hiding their true identity. This suggests that online memory detection might become a valuable tool for forensic applications.

  8. Endoperoxides Revealed as Origin of the Toxicity of Graphene Oxide.

    PubMed

    Pieper, Hanna; Chercheja, Serghei; Eigler, Siegfried; Halbig, Christian E; Filipovic, Milos R; Mokhir, Andriy

    2016-01-04

    Potential biomedicinal applications of graphene oxide (GO), for example, as a carrier of biomolecules or a reagent for photothermal therapy and biosensing, are limited by its cytotoxicity and mutagenicity. It is believed that these properties are at least partially caused by GO-induced oxidative stress in cells. However, it is not known which chemical fragments of GO are responsible for this unfavorable effect. We generated four GOs containing variable redox-active groups on the surface, including Mn(2+), C-centered radicals, and endoperoxides (EPs). A comparison of the abilities of these materials to generate reactive oxygen species in human cervical cancer cells revealed that EPs play a crucial role in GO-induced oxidative stress. These data could be applied to the rational design of biocompatible nontoxic GOs for biomedical applications.

  9. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    PubMed Central

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-01-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution. PMID:26673816

  10. Comparative genomics reveals insights into avian genome evolution and adaptation.

    PubMed

    Zhang, Guojie; Li, Cai; Li, Qiye; Li, Bo; Larkin, Denis M; Lee, Chul; Storz, Jay F; Antunes, Agostinho; Greenwold, Matthew J; Meredith, Robert W; Ödeen, Anders; Cui, Jie; Zhou, Qi; Xu, Luohao; Pan, Hailin; Wang, Zongji; Jin, Lijun; Zhang, Pei; Hu, Haofu; Yang, Wei; Hu, Jiang; Xiao, Jin; Yang, Zhikai; Liu, Yang; Xie, Qiaolin; Yu, Hao; Lian, Jinmin; Wen, Ping; Zhang, Fang; Li, Hui; Zeng, Yongli; Xiong, Zijun; Liu, Shiping; Zhou, Long; Huang, Zhiyong; An, Na; Wang, Jie; Zheng, Qiumei; Xiong, Yingqi; Wang, Guangbiao; Wang, Bo; Wang, Jingjing; Fan, Yu; da Fonseca, Rute R; Alfaro-Núñez, Alonzo; Schubert, Mikkel; Orlando, Ludovic; Mourier, Tobias; Howard, Jason T; Ganapathy, Ganeshkumar; Pfenning, Andreas; Whitney, Osceola; Rivas, Miriam V; Hara, Erina; Smith, Julia; Farré, Marta; Narayan, Jitendra; Slavov, Gancho; Romanov, Michael N; Borges, Rui; Machado, João Paulo; Khan, Imran; Springer, Mark S; Gatesy, John; Hoffmann, Federico G; Opazo, Juan C; Håstad, Olle; Sawyer, Roger H; Kim, Heebal; Kim, Kyu-Won; Kim, Hyeon Jeong; Cho, Seoae; Li, Ning; Huang, Yinhua; Bruford, Michael W; Zhan, Xiangjiang; Dixon, Andrew; Bertelsen, Mads F; Derryberry, Elizabeth; Warren, Wesley; Wilson, Richard K; Li, Shengbin; Ray, David A; Green, Richard E; O'Brien, Stephen J; Griffin, Darren; Johnson, Warren E; Haussler, David; Ryder, Oliver A; Willerslev, Eske; Graves, Gary R; Alström, Per; Fjeldså, Jon; Mindell, David P; Edwards, Scott V; Braun, Edward L; Rahbek, Carsten; Burt, David W; Houde, Peter; Zhang, Yong; Yang, Huanming; Wang, Jian; Jarvis, Erich D; Gilbert, M Thomas P; Wang, Jun

    2014-12-12

    Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits.

  11. Comparative genomics reveals insights into avian genome evolution and adaptation

    PubMed Central

    Zhang, Guojie; Li, Cai; Li, Qiye; Li, Bo; Larkin, Denis M.; Lee, Chul; Storz, Jay F.; Antunes, Agostinho; Greenwold, Matthew J.; Meredith, Robert W.; Ödeen, Anders; Cui, Jie; Zhou, Qi; Xu, Luohao; Pan, Hailin; Wang, Zongji; Jin, Lijun; Zhang, Pei; Hu, Haofu; Yang, Wei; Hu, Jiang; Xiao, Jin; Yang, Zhikai; Liu, Yang; Xie, Qiaolin; Yu, Hao; Lian, Jinmin; Wen, Ping; Zhang, Fang; Li, Hui; Zeng, Yongli; Xiong, Zijun; Liu, Shiping; Zhou, Long; Huang, Zhiyong; An, Na; Wang, Jie; Zheng, Qiumei; Xiong, Yingqi; Wang, Guangbiao; Wang, Bo; Wang, Jingjing; Fan, Yu; da Fonseca, Rute R.; Alfaro-Núñez, Alonzo; Schubert, Mikkel; Orlando, Ludovic; Mourier, Tobias; Howard, Jason T.; Ganapathy, Ganeshkumar; Pfenning, Andreas; Whitney, Osceola; Rivas, Miriam V.; Hara, Erina; Smith, Julia; Farré, Marta; Narayan, Jitendra; Slavov, Gancho; Romanov, Michael N; Borges, Rui; Machado, João Paulo; Khan, Imran; Springer, Mark S.; Gatesy, John; Hoffmann, Federico G.; Opazo, Juan C.; Håstad, Olle; Sawyer, Roger H.; Kim, Heebal; Kim, Kyu-Won; Kim, Hyeon Jeong; Cho, Seoae; Li, Ning; Huang, Yinhua; Bruford, Michael W.; Zhan, Xiangjiang; Dixon, Andrew; Bertelsen, Mads F.; Derryberry, Elizabeth; Warren, Wesley; Wilson, Richard K; Li, Shengbin; Ray, David A.; Green, Richard E.; O’Brien, Stephen J.; Griffin, Darren; Johnson, Warren E.; Haussler, David; Ryder, Oliver A.; Willerslev, Eske; Graves, Gary R.; Alström, Per; Fjeldså, Jon; Mindell, David P.; Edwards, Scott V.; Braun, Edward L.; Rahbek, Carsten; Burt, David W.; Houde, Peter; Zhang, Yong; Yang, Huanming; Wang, Jian; Jarvis, Erich D.; Gilbert, M. Thomas P.; Wang, Jun

    2015-01-01

    Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits. PMID:25504712

  12. Suit to proceed in claim that pharmacy revealed HIV status.

    PubMed

    1999-12-24

    A Federal judge in Milwaukee left intact a claim that the Osco Drug Store chain negligently caused ¿John Doe' emotional distress and exposed him to harassment. The store published, without his permission, his letter of thanks to an Osco pharmacist for helping him to obtain the protease inhibitor Norvir. After the letter was printed in an internal newsletter and posted at the store, John Doe received anonymous phone calls and his house was vandalized. The judge called Osco's argument that Osco was entrapped into revealing John Doe's HIV status "absurd." The judge dismissed the violation of privacy counts stating that Wisconsin's privacy law was only linked to HIV test results, which the Osco document did not mention. However, the judge left intact the claim of negligent infliction of emotional distress. The plaintiff's attorney plans to file a motion for reconsideration of the privacy and HIV information claims in Florida, John Doe's primary area of residence.

  13. Surprise maximization reveals the community structure of complex networks

    PubMed Central

    Aldecoa, Rodrigo; Marín, Ignacio

    2013-01-01

    How to determine the community structure of complex networks is an open question. It is critical to establish the best strategies for community detection in networks of unknown structure. Here, using standard synthetic benchmarks, we show that none of the algorithms hitherto developed for community structure characterization perform optimally. Significantly, evaluating the results according to their modularity, the most popular measure of the quality of a partition, systematically provides mistaken solutions. However, a novel quality function, called Surprise, can be used to elucidate which is the optimal division into communities. Consequently, we show that the best strategy to find the community structure of all the networks examined involves choosing among the solutions provided by multiple algorithms the one with the highest Surprise value. We conclude that Surprise maximization precisely reveals the community structure of complex networks. PMID:23320141

  14. Insights revealed by rodent models of sugar binge eating.

    PubMed

    Murray, Susan M; Tulloch, Alastair J; Chen, Eunice Y; Avena, Nicole M

    2015-12-01

    Binge eating is seen across the spectrum of eating disorder diagnoses as well as among individuals who do not meet diagnostic criteria. Analyses of the specific types of foods that are frequently binged upon reveal that sugar-rich items feature prominently in binge-type meals, making the effects of binge consumption of sugar an important focus of study. One avenue to do this involves the use of animal models. Foundational and recent studies of animal models of sugar bingeing, both outlined here, lend insight into the various neurotransmitters and neuropeptides that may participate in or be altered by this behavior. Further, several preclinical studies incorporating sugar bingeing paradigms have explored the utility of pharmacological agents that target such neural systems for reducing sugar bingeing in an effort to enhance clinical treatment. Indeed, the translational implications of findings generated using animal models of sugar bingeing are considered here, along with potential avenues for further study.

  15. Direct brain recordings reveal hippocampal rhythm underpinnings of language processing

    PubMed Central

    Anderson, Kristopher L.; Lin, Jack J.; Dewar, Callum; Parvizi, Josef; Dronkers, Nina F.; Knight, Robert T.

    2016-01-01

    Language is classically thought to be supported by perisylvian cortical regions. Here we provide intracranial evidence linking the hippocampal complex to linguistic processing. We used direct recordings from the hippocampal structures to investigate whether theta oscillations, pivotal in memory function, track the amount of contextual linguistic information provided in sentences. Twelve participants heard sentences that were either constrained (“She locked the door with the”) or unconstrained (“She walked in here with the”) before presentation of the final word (“key”), shown as a picture that participants had to name. Hippocampal theta power increased for constrained relative to unconstrained contexts during sentence processing, preceding picture presentation. Our study implicates hippocampal theta oscillations in a language task using natural language associations that do not require memorization. These findings reveal that the hippocampal complex contributes to language in an active fashion, relating incoming words to stored semantic knowledge, a necessary process in the generation of sentence meaning. PMID:27647880

  16. Early MAVEN Deep Dip campaign reveals thermosphere and ionosphere variability

    NASA Astrophysics Data System (ADS)

    Bougher, S.; Jakosky, B.; Halekas, J.; Grebowsky, J.; Luhmann, J.; Mahaffy, P.; Connerney, J.; Eparvier, F.; Ergun, R.; Larson, D.; McFadden, J.; Mitchell, D.; Schneider, N.; Zurek, R.; Mazelle, C.; Andersson, L.; Andrews, D.; Baird, D.; Baker, D. N.; Bell, J. M.; Benna, M.; Brain, D.; Chaffin, M.; Chamberlin, P.; Chaufray, J.-Y.; Clarke, J.; Collinson, G.; Combi, M.; Crary, F.; Cravens, T.; Crismani, M.; Curry, S.; Curtis, D.; Deighan, J.; Delory, G.; Dewey, R.; DiBraccio, G.; Dong, C.; Dong, Y.; Dunn, P.; Elrod, M.; England, S.; Eriksson, A.; Espley, J.; Evans, S.; Fang, X.; Fillingim, M.; Fortier, K.; Fowler, C. M.; Fox, J.; Gröller, H.; Guzewich, S.; Hara, T.; Harada, Y.; Holsclaw, G.; Jain, S. K.; Jolitz, R.; Leblanc, F.; Lee, C. O.; Lee, Y.; Lefevre, F.; Lillis, R.; Livi, R.; Lo, D.; Ma, Y.; Mayyasi, M.; McClintock, W.; McEnulty, T.; Modolo, R.; Montmessin, F.; Morooka, M.; Nagy, A.; Olsen, K.; Peterson, W.; Rahmati, A.; Ruhunusiri, S.; Russell, C. T.; Sakai, S.; Sauvaud, J.-A.; Seki, K.; Steckiewicz, M.; Stevens, M.; Stewart, A. I. F.; Stiepen, A.; Stone, S.; Tenishev, V.; Thiemann, E.; Tolson, R.; Toublanc, D.; Vogt, M.; Weber, T.; Withers, P.; Woods, T.; Yelle, R.

    2015-11-01

    The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above the well-mixed atmosphere, the layer of peak extreme ultraviolet heating and primary reservoir for atmospheric escape. In situ measurements of the upper atmosphere reveal previously unmeasured populations of neutral and charged particles, the homopause altitude at approximately 130 kilometers, and an unexpected level of variability both on an orbit-to-orbit basis and within individual orbits. These observations help constrain volatile escape processes controlled by thermosphere and ionosphere structure and variability.

  17. Early MAVEN Deep Dip campaign reveals thermosphere and ionosphere variability.

    PubMed

    Bougher, S; Jakosky, B; Halekas, J; Grebowsky, J; Luhmann, J; Mahaffy, P; Connerney, J; Eparvier, F; Ergun, R; Larson, D; McFadden, J; Mitchell, D; Schneider, N; Zurek, R; Mazelle, C; Andersson, L; Andrews, D; Baird, D; Baker, D N; Bell, J M; Benna, M; Brain, D; Chaffin, M; Chamberlin, P; Chaufray, J-Y; Clarke, J; Collinson, G; Combi, M; Crary, F; Cravens, T; Crismani, M; Curry, S; Curtis, D; Deighan, J; Delory, G; Dewey, R; DiBraccio, G; Dong, C; Dong, Y; Dunn, P; Elrod, M; England, S; Eriksson, A; Espley, J; Evans, S; Fang, X; Fillingim, M; Fortier, K; Fowler, C M; Fox, J; Gröller, H; Guzewich, S; Hara, T; Harada, Y; Holsclaw, G; Jain, S K; Jolitz, R; Leblanc, F; Lee, C O; Lee, Y; Lefevre, F; Lillis, R; Livi, R; Lo, D; Ma, Y; Mayyasi, M; McClintock, W; McEnulty, T; Modolo, R; Montmessin, F; Morooka, M; Nagy, A; Olsen, K; Peterson, W; Rahmati, A; Ruhunusiri, S; Russell, C T; Sakai, S; Sauvaud, J-A; Seki, K; Steckiewicz, M; Stevens, M; Stewart, A I F; Stiepen, A; Stone, S; Tenishev, V; Thiemann, E; Tolson, R; Toublanc, D; Vogt, M; Weber, T; Withers, P; Woods, T; Yelle, R

    2015-11-06

    The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above the well-mixed atmosphere, the layer of peak extreme ultraviolet heating and primary reservoir for atmospheric escape. In situ measurements of the upper atmosphere reveal previously unmeasured populations of neutral and charged particles, the homopause altitude at approximately 130 kilometers, and an unexpected level of variability both on an orbit-to-orbit basis and within individual orbits. These observations help constrain volatile escape processes controlled by thermosphere and ionosphere structure and variability.

  18. An Addison disease revealed with a serious hyponatremia.

    PubMed

    Maguet, Hadrien; Carreau, Agnès; Hautefeuille, Serge; Bonnin, Pierre; Beaune, Gaspard

    2017-02-01

    We present the case of an Addison's disease revealed by a serious hyponatremia. The serum concentration of ACTH and 21-hydroxylase antibodies were increased and lead to the diagnosis. The cortisol blood level was lowered but required to take into account the stress induced by the hospitalisation of the patient. Addison's disease is characterized by the destruction of the adrenal cortex. Autoimmune adrenalitis is the main cause of adrenal insufficiency. Treatment involves normalisation of sodium concentration and corticosteroids replacement. With a good patient compliance, the survival rate of Addisonian patient is similar to that of the normal population. Management of patient requires vigilance because of the occurrence of others autoimmunes diseases during patient life.

  19. Early allelic selection in maize as revealed by ancient DNA.

    PubMed

    Jaenicke-Després, Viviane; Buckler, Ed S; Smith, Bruce D; Gilbert, M Thomas P; Cooper, Alan; Doebley, John; Pääbo, Svante

    2003-11-14

    Maize was domesticated from teosinte, a wild grass, by approximately 6300 years ago in Mexico. After initial domestication, early farmers continued to select for advantageous morphological and biochemical traits in this important crop. However, the timing and sequence of character selection are, thus far, known only for morphological features discernible in corn cobs. We have analyzed three genes involved in the control of plant architecture, storage protein synthesis, and starch production from archaeological maize samples from Mexico and the southwestern United States. The results reveal that the alleles typical of contemporary maize were present in Mexican maize by 4400 years ago. However, as recently as 2000 years ago, allelic selection at one of the genes may not yet have been complete.

  20. Experimental evolution reveals hidden diversity in evolutionary pathways.

    PubMed

    Lind, Peter A; Farr, Andrew D; Rainey, Paul B

    2015-03-25

    Replicate populations of natural and experimental organisms often show evidence of parallel genetic evolution, but the causes are unclear. The wrinkly spreader morph of Pseudomonas fluorescens arises repeatedly during experimental evolution. The mutational causes reside exclusively within three pathways. By eliminating these, 13 new mutational pathways were discovered with the newly arising WS types having fitnesses similar to those arising from the commonly passaged routes. Our findings show that parallel genetic evolution is strongly biased by constraints and we reveal the genetic bases. From such knowledge, and in instances where new phenotypes arise via gene activation, we suggest a set of principles: evolution proceeds firstly via pathways subject to negative regulation, then via promoter mutations and gene fusions, and finally via activation by intragenic gain-of-function mutations. These principles inform evolutionary forecasting and have relevance to interpreting the diverse array of mutations associated with clinically identical instances of disease in humans.

  1. Metagenome mining reveals polytheonamides as posttranslationally modified ribosomal peptides.

    PubMed

    Freeman, Michael F; Gurgui, Cristian; Helf, Maximilian J; Morinaka, Brandon I; Uria, Agustinus R; Oldham, Neil J; Sahl, Hans-Georg; Matsunaga, Shigeki; Piel, Jörn

    2012-10-19

    It is held as a paradigm that ribosomally synthesized peptides and proteins contain only l-amino acids. We demonstrate a ribosomal origin of the marine sponge-derived polytheonamides, exceptionally potent, giant natural-product toxins. Isolation of the biosynthetic genes from the sponge metagenome revealed a bacterial gene architecture. Only six candidate enzymes were identified for 48 posttranslational modifications, including 18 epimerizations and 17 methylations of nonactivated carbon centers. Three enzymes were functionally validated, which showed that a radical S-adenosylmethionine enzyme is responsible for the unidirectional epimerization of multiple and different amino acids. Collectively, these complex alterations create toxins that function as unimolecular minimalistic ion channels with near-femtomolar activity. This study broadens the biosynthetic scope of ribosomal systems and creates new opportunities for peptide and protein bioengineering.

  2. Spring-block model reveals region-like structures.

    PubMed

    Máté, Gabriell; Néda, Zoltán; Benedek, József

    2011-02-08

    A mechanical spring-block model is used for realizing an objective space partition of settlements from a geographic territory in region-like structures. The method is based on the relaxation-dynamics of the spring-block system and reveals in a hierarchical manner region-like entities at different spatial scales. It takes into account in an elegant manner both the spatiality of the elements and the connectivity relations among them. Spatiality is taken into account by using the geographic coordinates of the settlements, and by detecting the neighbors with the help of a Delaunay triangulation. Connectivity between neighboring settlements are quantified using a Pearson-like correlation for the relative variation of a relevant socio-economic parameter (population size, GDP, tax payed per inhabitant, etc.). The method is implemented in an interactive JAVA application and it is applied with success for an artificially generated society and for the case of USA, Hungary and Transylvania.

  3. Structure of mega-hemocyanin reveals protein origami in snails.

    PubMed

    Gatsogiannis, Christos; Hofnagel, Oliver; Markl, Jürgen; Raunser, Stefan

    2015-01-06

    Mega-hemocyanin is a 13.5 MDa oxygen transporter found in the hemolymph of some snails. Similar to typical gastropod hemocyanins, it is composed of 400 kDa building blocks but has additional 550 kDa subunits. Together, they form a large, completely filled cylinder. The structural basis for this highly complex protein packing is not known so far. Here, we report the electron cryomicroscopy (cryo-EM) structure of mega-hemocyanin complexes from two different snail species. The structures reveal that mega-hemocyanin is composed of flexible building blocks that differ in their conformation, but not in their primary structure. Like a protein origami, these flexible blocks are optimally packed, implementing different local symmetries and pseudosymmetries. A comparison between the two structures suggests a surprisingly simple evolutionary mechanism leading to these large oxygen transporters.

  4. [Hodgkin disease revealed by a nephrotic syndrome: A case report].

    PubMed

    Cheptou, M; Pichault, V; Campagni, R; Vodoff, M-V; Fischbach, M; Paillard, C

    2015-12-01

    Pediatric nephrotic syndrome (NS) is most often idiopathic or primary but in rare cases, it can be secondary to neoplasia. We report on a case of steroid-resistant NS revealing as a paraneoplastic syndrome of Hodgkin disease (HD) in a 12-year-old boy. The onset of the NS can be earlier, later, or simultaneous to the HD. Treatment of the lymphoma allows the disappearance of the NS. In the case we observed, the diagnosis of HD was delayed because HD presented with an isolated, hilar adenopathy in the absence of retroperitoneal or peripheral locations. In children aged 10 years or more presenting with NS, steroid-resistant or otherwise, a possible paraneoplastic origin such as Hodgkin lymphoma should always be taken into consideration and eventually eliminated.

  5. High throughput sequencing reveals a novel fabavirus infecting sweet cherry.

    PubMed

    Villamor, D E V; Pillai, S S; Eastwell, K C

    2017-03-01

    The genus Fabavirus currently consists of five species represented by viruses that infect a wide range of hosts but none reported from temperate climate fruit trees. A virus with genomic features resembling fabaviruses (tentatively named Prunus virus F, PrVF) was revealed by high throughput sequencing of extracts from a sweet cherry tree (Prunus avium). PrVF was subsequently shown to be graft transmissible and further identified in three other non-symptomatic Prunus spp. from different geographical locations. Two genetic variants of RNA1 and RNA2 coexisted in the same samples. RNA1 consisted of 6,165 and 6,163 nucleotides, and RNA2 consisted of 3,622 and 3,468 nucleotides.

  6. Treated-skin temperature regularities revealed by IR thermography

    NASA Astrophysics Data System (ADS)

    Vainer, Boris G.

    2001-03-01

    Experimental results disclosing temperature change of human skin affected by various unnatural factors are presented in detail. Thermograms are obtained with the IR thermograph containing high performance InAs CID FPA-based photosensitive unit. Using logarithmic scale of time, evolution of skin temperature after moistening, spirit sponging, and olive oil lubrication is investigated. A comparative analysis of the resulting effects of treatments including alpha-hydroxy acid, cosmetic regenerating cream, spirit, and water, is made. Quantitative distinctions between skin regions characterized by ordinary, and depleted blood supply, including areas located directly above surface main vessels, are revealed. Strongly logarithmic time- dependence of a skin temperature is discovered when the skin is cooled down after its preliminary heating with a hot wax. Non-monotonic change of a local temperature during electrically active procedure is described. Low level light therapy equipment is also applied. A special role of the temperature of nose is discussed.

  7. Quasisoft X-ray Sources: their physical natures revealed

    NASA Astrophysics Data System (ADS)

    Di Stefano, Rosanne; Primini, Francis A.; Guo, Jincheng; Liu, Jifeng

    2016-04-01

    Quasisoft X-ray sources (QSSs) have been the Mona Lisa of X-ray sources. They have remained enigmatic, even though we have known of their existence and basic properties for more than a decade. QSSs have X-ray luminosities greater than 10^{36} erg/s, but emit few or no photons above 2 keV. They were discovered in external galaxies during searches for softer sources, supersoft X-ray sources (SSSs). Every external galaxy contains QSSs, but it has been challenging to find any in the Milky Way and the Magellanic Clouds. Recent work, however, reveals that a significant fraction of QSSs may be black holes. We review what is known about QSSs to date, because this obscure class of objects may at last to be ready for "prime time'', capable of identifying BHs in a wide range of Galactic environments.

  8. Biosensor reveals multiple sources for mitochondrial NAD⁺.

    PubMed

    Cambronne, Xiaolu A; Stewart, Melissa L; Kim, DongHo; Jones-Brunette, Amber M; Morgan, Rory K; Farrens, David L; Cohen, Michael S; Goodman, Richard H

    2016-06-17

    Nicotinamide adenine dinucleotide (NAD(+)) is an essential substrate for sirtuins and poly(adenosine diphosphate-ribose) polymerases (PARPs), which are NAD(+)-consuming enzymes localized in the nucleus, cytosol, and mitochondria. Fluctuations in NAD(+) concentrations within these subcellular compartments are thought to regulate the activity of NAD(+)-consuming enzymes; however, the challenge in measuring compartmentalized NAD(+) in cells has precluded direct evidence for this type of regulation. We describe the development of a genetically encoded fluorescent biosensor for directly monitoring free NAD(+) concentrations in subcellular compartments. We found that the concentrations of free NAD(+) in the nucleus, cytoplasm, and mitochondria approximate the Michaelis constants for sirtuins and PARPs in their respective compartments. Systematic depletion of enzymes that catalyze the final step of NAD(+) biosynthesis revealed cell-specific mechanisms for maintaining mitochondrial NAD(+) concentrations.

  9. MNase titration reveals differences between nucleosome occupancy and chromatin accessibility

    PubMed Central

    Mieczkowski, Jakub; Cook, April; Bowman, Sarah K.; Mueller, Britta; Alver, Burak H.; Kundu, Sharmistha; Deaton, Aimee M.; Urban, Jennifer A.; Larschan, Erica; Park, Peter J.; Kingston, Robert E.; Tolstorukov, Michael Y.

    2016-01-01

    Chromatin accessibility plays a fundamental role in gene regulation. Nucleosome placement, usually measured by quantifying protection of DNA from enzymatic digestion, can regulate accessibility. We introduce a metric that uses micrococcal nuclease (MNase) digestion in a novel manner to measure chromatin accessibility by combining information from several digests of increasing depths. This metric, MACC (MNase accessibility), quantifies the inherent heterogeneity of nucleosome accessibility in which some nucleosomes are seen preferentially at high MNase and some at low MNase. MACC interrogates each genomic locus, measuring both nucleosome location and accessibility in the same assay. MACC can be performed either with or without a histone immunoprecipitation step, and thereby compares histone and non-histone protection. We find that changes in accessibility at enhancers, promoters and other regulatory regions do not correlate with changes in nucleosome occupancy. Moreover, high nucleosome occupancy does not necessarily preclude high accessibility, which reveals novel principles of chromatin regulation. PMID:27151365

  10. Satellite nighttime lights reveal increasing human exposure to floods worldwide

    NASA Astrophysics Data System (ADS)

    Ceola, Serena; Laio, Francesco; Montanari, Alberto

    2014-10-01

    River floods claim thousands of lives every year, but effective and high-resolution methods to map human exposure to floods at the global scale are still lacking. We use satellite nightlight data to prove that nocturnal lights close to rivers are consistently related to flood damages. We correlate global data of economic losses caused by flooding events with nighttime lights and find that increasing nightlights are associated to flood damage intensification. Then, we analyze the temporal evolution of nightlights along the river network all over the world from 1992 to 2012 and obtain a global map of nightlight trends, which we associate with increasing human exposure to floods, at 1 km2 resolution. An enhancement of exposure to floods worldwide, particularly in Africa and Asia, is revealed, which may exacerbate the projected effects of climate change on flood-related losses and therefore argues for the development of valuable flood preparedness and mitigation strategies.

  11. Subfield profitability analysis reveals an economic case for cropland diversification

    NASA Astrophysics Data System (ADS)

    Brandes, E.; McNunn, G. S.; Schulte, L. A.; Bonner, I. J.; Muth, D. J.; Babcock, B. A.; Sharma, B.; Heaton, E. A.

    2016-01-01

    Public agencies and private enterprises increasingly desire to achieve ecosystem service outcomes in agricultural systems, but are limited by perceived conflicts between economic and ecosystem service goals and a lack of tools enabling effective operational management. Here we use Iowa—an agriculturally homogeneous state representative of the Maize Belt—to demonstrate an economic rationale for cropland diversification at the subfield scale. We used a novel computational framework that integrates disparate but publicly available data to map ˜3.3 million unique potential management polygons (9.3 Mha) and reveal subfield opportunities to increase overall field profitability. We analyzed subfield profitability for maize/soybean fields during 2010-2013—four of the most profitable years in recent history—and projected results for 2015. While cropland operating at a loss of US 250 ha-1 or more was negligible between 2010 and 2013 at 18 000-190 000 ha (<2% of row-crop land), the extent of highly unprofitable land increased to 2.5 Mha, or 27% of row-crop land, in the 2015 projection. Aggregation of these areas to the township level revealed ‘hotspots’ for potential management change in Western, Central, and Northeast Iowa. In these least profitable areas, incorporating conservation management that breaks even (e.g., planting low-input perennials), into low-yielding portions of fields could increase overall cropland profitability by 80%. This approach is applicable to the broader region and differs substantially from the status quo of ‘top-down’ land management for conservation by harnessing private interest to align profitability with the production of ecosystem services.

  12. Martian Channels and their Geomorphologic Development as Revealed by MOLA

    NASA Astrophysics Data System (ADS)

    Lanz, J. K.; Hebenstreit, R.; Jaumann, R.

    2000-08-01

    One of the most striking features of Mars are enormous channels and channel systems that shape its surface. Outflow channels more than 2000 km long and several 100 km wide reveal a vast amount of erosional landforms resembling terrestrial flood features. Runoff channels with dendritic networks and fretted channels with features resembling terrestrial rock glaciers show the variety of processes that shaped the landscape. Newly released Mars Orbiting Laser Altimeter (MOLA) tracks give a detailed insight in the development of the shape of cross sections along those Martian channels. We have studied numerous such cross sections (sometimes more than 100 per channel!) looking for the processes involved in the evolution of the channels. The MOLA data also allowed the generation of longitudinal profiles, by extracting the deepest points of all cross sections as given by the MOLA tracks.Cross sections of runoff channels (e.g. Nirgal Vallis) showed a striking similarity with terrestrial channel networks that were formed by sapping. They are U-shaped in the upper parts of the channels and box-shaped in the lower parts. They generally increase in width and depth downstream but often stagnate over long distances. No inner channels were found, possibly because of the limited vertical resolution of the MOLA tracks. The longitudinal profile of Nirgal Vallis shows a continuous downstream slope as one would expect from a channel formed by sapping as well as by surface runoff. These observations currently are compared with MOLA tracks of the more dendritic type of runoff channels hoping to find similarities or differences that might reveal more about the evolution of those channels and the processes involved.

  13. Vibrio cholerae classical biotype strains reveal distinct signatures in Mexico.

    PubMed

    Alam, Munirul; Islam, M Tarequl; Rashed, Shah Manzur; Johura, Fatema-tuz; Bhuiyan, Nurul A; Delgado, Gabriela; Morales, Rosario; Mendez, Jose Luis; Navarro, Armando; Watanabe, Haruo; Hasan, Nur-A; Colwell, Rita R; Cravioto, Alejandro

    2012-07-01

    Vibrio cholerae O1 classical (CL) biotype caused the fifth and sixth pandemics, and probably the earlier cholera pandemics, before the El Tor (ET) biotype initiated the seventh pandemic in Asia in the 1970s by completely displacing the CL biotype. Although the CL biotype was thought to be extinct in Asia and although it had never been reported from Latin America, V. cholerae CL and ET biotypes, including a hybrid ET, were found associated with areas of cholera endemicity in Mexico between 1991 and 1997. In this study, CL biotype strains isolated from areas of cholera endemicity in Mexico between 1983 and 1997 were characterized in terms of major phenotypic and genetic traits and compared with CL biotype strains isolated in Bangladesh between 1962 and 1989. According to sero- and biotyping data, all V. cholerae strains tested had the major phenotypic and genotypic characteristics specific for the CL biotype. Antibiograms revealed the majority of the Bangladeshi strains to be resistant to trimethoprim-sulfamethoxazole, furazolidone, ampicillin, and gentamicin, while the Mexican strains were sensitive to all of these drugs, as well as to ciprofloxacin, erythromycin, and tetracycline. Pulsed-field gel electrophoresis (PFGE) of NotI-digested genomic DNA revealed characteristic banding patterns for all of the CL biotype strains although the Mexican strains differed from the Bangladeshi strains in 1 to 2 DNA bands. The difference was subtle but consistent, as confirmed by the subclustering patterns in the PFGE-based dendrogram, and can serve as a regional signature, suggesting the pre-1991 existence and evolution of the CL biotype strains in the Americas, independent from Asia.

  14. Ethiopian population dermatoglyphic study reveals linguistic stratification of diversity.

    PubMed

    Yohannes, Seile; Bekele, Endashaw

    2015-01-01

    The manifestation of ethnic, blood type, & gender-wise population variations regarding Dermatoglyphic manifestations are of interest to assess intra-group diversity and differentiation. The present study reports on the analysis of qualitaive and quantitative finger Dermatoglyphic traits of 382 individuals cross-sectionally sampled from an administrative region of Ethiopia, consisting of five ethnic cohorts from the Afro-Asiatic & Nilo-Saharan affiliations. These Dermatoglyphic parameters were then applied in the assessment of diversity & differentiation, including Heterozygosity, Fixation, Panmixia, Wahlund's variance, Nei's measure of genetic diversity, and thumb & finger pattern genotypes, which were inturn used in homology inferences as summarized by a Neighbour-Joining tree constructed from Nei's standard genetic distance. Results revealed significant correlation between Dermatoglyphics & population parameters that were further found to be in concordance with the historical accounts of the ethnic groups. Such inductions as the ancient north-eastern presence and subsequent admixure events of the Oromos (PII= 15.01), the high diversity of the Amharas (H= 0.1978, F= 0.6453, and P= 0.4144), and the Nilo-Saharan origin of the Berta group (PII= 10.66) are evidences to this. The study has further tested the possibility of applying Dermatoglyphics in population genetic & anthropologic research, highlighting on the prospect of developing a method to trace back population origins & ancient movement patterns. Additionally, linguistic clustering was deemed significant for the Ethiopian population, coinciding with recent genome wide studies that have ascertained that linguistic clustering as to being more crucial than the geographical patterning in the Ethiopian context. Finally, Dermatoglyphic markers have been proven to be endowed with a strong potential as non-invasive preliminary tools applicable prior to genetic studies to analyze ethnically sub-divided populations and

  15. Architecture of cognitive flexibility revealed by lesion mapping.

    PubMed

    Barbey, Aron K; Colom, Roberto; Grafman, Jordan

    2013-11-15

    Neuroscience has made remarkable progress in understanding the architecture of human intelligence, identifying a distributed network of brain structures that support goal-directed, intelligent behavior. However, the neural foundations of cognitive flexibility and adaptive aspects of intellectual function remain to be well characterized. Here, we report a human lesion study (n=149) that investigates the neural bases of key competencies of cognitive flexibility (i.e., mental flexibility and the fluent generation of new ideas) and systematically examine their contributions to a broad spectrum of cognitive and social processes, including psychometric intelligence (Wechsler Adult Intelligence Scale), emotional intelligence (Mayer, Salovey, Caruso Emotional Intelligence Test), and personality (Neuroticism-Extraversion-Openness Personality Inventory). Latent variable modeling was applied to obtain error-free indices of each factor, followed by voxel-based lesion-symptom mapping to elucidate their neural substrates. Regression analyses revealed that latent scores for psychometric intelligence reliably predict latent scores for cognitive flexibility (adjusted R(2)=0.94). Lesion mapping results further indicated that these convergent processes depend on a shared network of frontal, temporal, and parietal regions, including white matter association tracts, which bind these areas into an integrated system. A targeted analysis of the unique variance explained by cognitive flexibility further revealed selective damage within the right superior temporal gyrus, a region known to support insight and the recognition of novel semantic relations. The observed findings motivate an integrative framework for understanding the neural foundations of adaptive behavior, suggesting that core elements of cognitive flexibility emerge from a distributed network of brain regions that support specific competencies for human intelligence.

  16. Replication Study: Melanoma genome sequencing reveals frequent PREX2 mutations

    PubMed Central

    Horrigan, Stephen K; Courville, Pascal; Sampey, Darryl; Zhou, Faren; Cai, Steve

    2017-01-01

    In 2015, as part of the Reproducibility Project: Cancer Biology, we published a Registered Report (Chroscinski et al., 2014) that described how we intended to replicate selected experiments from the paper "Melanoma genome sequencing reveals frequent PREX2 mutations" (Berger et al., 2012). Here we report the results of those experiments. We regenerated cells stably expressing ectopic wild-type and mutant phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchange factor 2 (PREX2) using the same immortalized human NRASG12D melanocytes as the original study. Evaluation of PREX2 expression in these newly generated stable cells revealed varying levels of expression among the PREX2 isoforms, which was also observed in the stable cells made in the original study (Figure S6A; Berger et al., 2012). Additionally, ectopically expressed PREX2 was found to be at least 5 times above endogenous PREX2 expression. The monitoring of tumor formation of these stable cells in vivo resulted in no statistically significant difference in tumor-free survival driven by PREX2 variants, whereas the original study reported that these PREX2 mutations increased the rate of tumor incidence compared to controls (Figure 3B and S6B; Berger et al., 2012). Surprisingly, the median tumor-free survival was 1 week in this replication attempt, while 70% of the control mice were reported to be tumor-free after 9 weeks in the original study. The rapid tumor onset observed in this replication attempt, compared to the original study, makes the detection of accelerated tumor growth in PREX2 expressing NRASG12D melanocytes extremely difficult. Finally, we report meta-analyses for each result. DOI: http://dx.doi.org/10.7554/eLife.21634.001 PMID:28100394

  17. Regulatory phenotyping reveals important diversity within the species Lactococcus lactis.

    PubMed

    Bachmann, Herwig; Starrenburg, Marjo J C; Dijkstra, Annereinou; Molenaar, Douwe; Kleerebezem, Michiel; Rademaker, Jan L W; van Hylckama Vlieg, Johan E T

    2009-09-01

    The diversity in regulatory phenotypes among a collection of 84 Lactococcus lactis strains isolated from dairy and nondairy origin was explored. The specific activities of five enzymes were assessed in cell extracts of all strains grown in two different media, a nutritionally rich broth and a relatively poor chemically defined medium. The five investigated enzymes, branched chain aminotransferase (BcaT), aminopeptidase N (PepN), X-prolyl dipeptidyl peptidase (PepX), alpha-hydroxyisocaproic acid dehydrogenase (HicDH), and esterase, are involved in nitrogen and fatty acid metabolism and catalyze key steps in the production of important dairy flavor compounds. The investigated cultures comprise 75 L. lactis subsp. lactis isolates (including 7 L. lactis subsp. lactis biovar diacetylactis isolates) and 9 L. lactis subsp. cremoris isolates. All L. lactis subsp. cremoris and 22 L. lactis subsp. lactis (including 6 L. lactis subsp. lactis biovar diacetylactis) cultures originated from a dairy environment. All other cultures originated from (fermented) plant materials and were isolated at different geographic locations. Correlation analysis of specific enzyme activities revealed significantly different regulatory phenotypes for dairy and nondairy isolates. The enzyme activities in the two investigated media were in general poorly correlated and revealed a high degree of regulatory diversity within this collection of closely related strains. To the best of our knowledge, these results represent the most extensive diversity analysis of regulatory phenotypes within a single bacterial species to date. The presented findings underline the importance of the availability of screening procedures for, e.g., industrially relevant enzyme activities in models closely mimicking application conditions. Moreover, they corroborate the notion that regulatory changes are important drivers of evolution.

  18. Probing lysozyme conformation with light reveals a new folding intermediate.

    PubMed

    Hamill, Andrea C; Wang, Shao-Chun; Lee, C Ted

    2005-11-22

    A means to control lysozyme conformation with light illumination has been developed using the interaction of the protein with a photoresponsive surfactant. Upon exposure to the appropriate wavelength of light, the azobenzene surfactant undergoes a reversible photoisomerization, with the visible-light (trans) form being more hydrophobic than the UV-light (cis) form. As a result, surfactant binding to the protein and, thus, protein unfolding, can be tuned with light. Small-angle neutron scattering (SANS) measurements were used to provide detailed information of the protein conformation in solution. Shape-reconstruction methods applied to the SANS data indicate that under visible light the protein exhibits a native-like form at low surfactant concentrations, a partially swollen form at intermediate concentrations, and a swollen/unfolded form at higher surfactant concentrations. Furthermore, the SANS data combined with FT-IR spectroscopic analysis of the protein secondary structure reveal that unfolding occurs primarily in the alpha domain of lysozyme, while the beta domain remains relatively intact. Thus, the surfactant-unfolded intermediate of lysozyme appears to be a separate structure than the well-known alpha-domain intermediate of lysozyme that contains a folded alpha domain and unfolded beta domain. Because the interactions between the photosurfactant and protein can be tuned with light, illumination with UV light returns the protein to a native-like conformation. Fluorescence emission data of the nonpolar probe Nile red indicate that hydrophobic domains become available for probe partitioning in surfactant-protein solutions under visible light, while the availability of these hydrophobic domains to the probe decrease under UV light. Dynamic light scattering and UV-vis spectroscopic measurements further confirm the shape-reconstruction findings and reveal three discrete conformations of lysozyme. The results clearly demonstrate that visible light causes a

  19. Next Generation Sequencing Reveals the Hidden Diversity of Zooplankton Assemblages

    PubMed Central

    Harmer, Rachel A.; Somerfield, Paul J.; Atkinson, Angus

    2013-01-01

    Background Zooplankton play an important role in our oceans, in biogeochemical cycling and providing a food source for commercially important fish larvae. However, difficulties in correctly identifying zooplankton hinder our understanding of their roles in marine ecosystem functioning, and can prevent detection of long term changes in their community structure. The advent of massively parallel next generation sequencing technology allows DNA sequence data to be recovered directly from whole community samples. Here we assess the ability of such sequencing to quantify richness and diversity of a mixed zooplankton assemblage from a productive time series site in the Western English Channel. Methodology/Principle Findings Plankton net hauls (200 µm) were taken at the Western Channel Observatory station L4 in September 2010 and January 2011. These samples were analysed by microscopy and metagenetic analysis of the 18S nuclear small subunit ribosomal RNA gene using the 454 pyrosequencing platform. Following quality control a total of 419,041 sequences were obtained for all samples. The sequences clustered into 205 operational taxonomic units using a 97% similarity cut-off. Allocation of taxonomy by comparison with the National Centre for Biotechnology Information database identified 135 OTUs to species level, 11 to genus level and 1 to order, <2.5% of sequences were classified as unknowns. By comparison a skilled microscopic analyst was able to routinely enumerate only 58 taxonomic groups. Conclusions Metagenetics reveals a previously hidden taxonomic richness, especially for Copepoda and hard-to-identify meroplankton such as Bivalvia, Gastropoda and Polychaeta. It also reveals rare species and parasites. We conclude that Next Generation Sequencing of 18S amplicons is a powerful tool for elucidating the true diversity and species richness of zooplankton communities. While this approach allows for broad diversity assessments of plankton it may become increasingly

  20. Revealing parasite influence in metabolic pathways in Apicomplexa infected patients

    PubMed Central

    2010-01-01

    Background As an obligate intracellular parasite, Apicomplexa interacts with the host in the special living environment, competing for energy and nutrients from the host cells by manipulating the host metabolism. Previous studies of host-parasite interaction mainly focused on using cellular and biochemical methods to investigate molecular functions in metabolic pathways of parasite infected hosts. Computational approaches taking advantage of high-throughput biological data and topology of metabolic pathways have a great potential in revealing the details and mechanism of parasites-to-host interactions. A new analytical method was designed in this work to study host-parasite interactions in human cells infected with Plasmodium falciparum and Cryptosporidium parvum. Results We introduced a new method that analyzes the host metabolic pathways in divided parts: host specific subpathways and host-parasite common subpathways. Upon analysis on gene expression data from cells infected by Plasmodium falciparum or Cryptosporidium parvum, we found: (i) six host-parasite common subpathways and four host specific subpathways were significantly altered in plasmodium infected human cells; (ii) plasmodium utilized fatty acid biosynthesis and elongation, and Pantothenate and CoA biosynthesis to obtain nutrients from host environment; (iii) in Cryptosporidium parvum infected cells, most of the host-parasite common enzymes were down-regulated, whereas the host specific enzymes up-regulated; (iv) the down-regulation of common subpathways in host cells might be caused by competition for the substrates and up-regulation of host specific subpathways may be stimulated by parasite infection. Conclusion Results demonstrated a significantly coordinated expression pattern between the two groups of subpathways. The method helped expose the impact of parasite infection on host cell metabolism, which was previously concealed in the pathway enrichment analysis. Our approach revealed detailed

  1. ZnS quantum dot induced phase transitional changes and enhanced ferroelectric mesophase in QDs/FLC composites

    NASA Astrophysics Data System (ADS)

    Vimal, T.; Pandey, S.; Singh, D. P.; Gupta, S. K.; Agrahari, K.; Kumbhakar, P.; Kole, A. K.; Manohar, R.

    2017-01-01

    In the present study, we report the dielectric and electro - optical (E - O) study of ZnS quantum dots (QDs) dispersed ferroelectric liquid crystal (FLC) material. Change in the SmC*- SmA phase transition temperature has been investigated by the thermal study. Width of SmC* phase is found to be slightly increased due to the dispersion of ZnS QDs, which has also been observed in the dielectric and E - O study of composites. Fitting of spontaneous polarization curves on the temperature scale has been done theoretically to obtain the change in SmC*- SmA phase transition temperature. A significant modification in the FLC material parameters (like spontaneous polarization, optical response time, tilt angle and rotational viscosity) has been observed after the dispersion of QDs. These modifications are the consequences of the strong dipolar interaction between the FLC molecule and QDs. Significant fastening of the optical response time for low conc. of QDs dispersed FLC composite shows its utilization in advanced display devices.

  2. Phospholipid mesophases at solid interfaces: in-situ X-ray diffraction and spin-label studies.

    PubMed

    Rappolt, Michael; Amenitsch, Heinz; Strancar, Janez; Teixeira, Cilaine V; Kriechbaum, Manfred; Pabst, Georg; Majerowicz, Monika; Laggner, Peter

    2004-11-29

    In this work, we report on recent investigations, both on the global and on the local molecular architecture of supported phospholipid model membranes. A brief theoretical introduction explains how global structural information on supramolecular lipid ensembles can be retrieved from surface X-ray diffraction measurements as well as how spin-label electron paramagnetic resonance spectroscopy (EPR) provides complementary information on the local environment of probe molecules. The combination of especially designed X-ray cells with the technique of small- and wide-angle X-ray surface scattering makes it possible to explore various fields of lipid research and its applications. Examples for different physico-chemical conditions are presented: (i) in situ chemistry under excess of water conditions demonstrating how solid-supported lipid films sense salinity, (ii) the 3D electron density reconstruction of a vesicle-fusion intermediate under controlled humidity, and (iii) complementary temperature and pressure effects on oriented phospholipid samples. Further, special attention has been given to the influence of different film preparation techniques with respect to quality and the defect structure manifestation. To resolve the proportions and local properties of defects in a hydrated lipid-deposited surface, spin-label EPR was applied. The results from 9.6 GHz EPR as well as from 1.2 GHz EPR suggest the alignment to be in the range between 30% and 80%. In addition, slow time-dependent EPR measurements point to nano-structural rearrangements due to water flow and reduction of alignment quality.

  3. Molecular and crystal structures of p-heptyloxyphenyl p-hexyloxybenzoate and p-butyloxyphenyl p-heptyloxybenzoate: Mesophase design

    SciTech Connect

    Kuz'mina, L. G. Gunina, M. A.; Churakov, A. V.; Pestov, S. M.

    2013-03-15

    Two aromatic esters with the formulas C{sub 6}H{sub 13}-O-C{sub 6}H{sub 4}-C(O)O-C{sub 6}H{sub 4}-O-C{sub 7}H{sub 15} (1) and C{sub 7}H{sub 15}-O-C{sub 6}H{sub 4}-C(O)O-C{sub 6}H{sub 4}-O-C{sub 4}H{sub 9} (2) belonging to nematic liquid-crystal compounds were studied by X-ray diffraction. Compound 1 crystallizes in two modifications: monoclinic (1-m) and triclinic (1-tr). The crystal packing of 1 and 2 is built from alternating loosely packed aliphatic regions and closely packed aromatic regions. In crystal structures 1-m and 2, the aromatic regions are linked into chains by hydrogen bonds with the participation of the carbonyl oxygen atom of the ester group and the C-H fragment of the benzene ring, but these hydrogen bonds in 1-m are much weaker than in 2. In 1-m there are {pi}-stacking interactions between the molecules, resulting in the formation of centrosymmetric dimers with an interplanar distance of 3.45 A. In 1-tr, the aromatic fragments form a herringbone packing motif favorable for a two-dimensional network of directional C-H...{pi}-system interactions.

  4. HUBBLE REVEALS THE HEART OF THE WHIRLPOOL GALAXY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    New images from NASA's Hubble Space Telescope are helping researchers view in unprecedented detail the spiral arms and dust clouds of a nearby galaxy, which are the birth sites of massive and luminous stars. The Whirlpool galaxy, M51, has been one of the most photogenic galaxies in amateur and professional astronomy. Easily photographed and viewed by smaller telescopes, this celestial beauty is studied extensively in a range of wavelengths by large ground- and space-based observatories. This Hubble composite image shows visible starlight as well as light from the emission of glowing hydrogen, which is associated with the most luminous young stars in the spiral arms. M51, also known as NGC 5194, is having a close encounter with a nearby companion galaxy, NGC 5195, just off the upper edge of this image. The companion's gravitational pull is triggering star formation in the main galaxy, as seen in brilliant detail by numerous, luminous clusters of young and energetic stars. The bright clusters are highlighted in red by their associated emission from glowing hydrogen gas. This Wide Field Planetary Camera 2 image enables a research group, led by Nick Scoville (Caltech), to clearly define the structure of both the cold dust clouds and the hot hydrogen and link individual clusters to their parent dust clouds. Team members include M. Polletta (U. Geneva); S. Ewald and S. Stolovy (Caltech); R. Thompson and M. Rieke (U. of Arizona). Intricate structure is also seen for the first time in the dust clouds. Along the spiral arms, dust 'spurs' are seen branching out almost perpendicular to the main spiral arms. The regularity and large number of these features suggests to astronomers that previous models of 'two-arm' spiral galaxies may need to be revisited. The new images also reveal a dust disk in the nucleus, which may provide fuel for a nuclear black hole. The team is also studying this galaxy at near-infrared wavelengths with the NICMOS instrument onboard Hubble. At these

  5. Tripartite Mushroom Body Architecture Revealed by Antigenic Markers

    PubMed Central

    Crittenden, Jill R.; Skoulakis, Efthimios M.C.; Han, Kyung-An; Kalderon, Daniel; Davis, Ronald L.

    1998-01-01

    We have explored the organization of the axonal lobes in Drosophila mushroom bodies by using a panel of immunohistochemical markers. These markers consist of antibodies to eight proteins expressed preferentially in the mushroom bodies: DAMB, DCO, DRK, FASII, LEO, OAMB, PKA RII, and RUT. Previous to this work, four axonal lobes, two projecting dorsally (α and α′) and two medially (β and γ), had been described in Drosophila mushroom bodies. However, our analysis of immunohistochemically stained frontal and sagittal sections of the brain revealed three medially projecting lobes. The newly distinguished lobe, which we term β′, lies along the dorsal surface of β, just posterior to γ. In addition to resolving a fifth lobe, our studies revealed that there are specific lobe sets defined by equivalent marker expression levels. These sets are (1) the α and β lobes, (2) the α′ and β′ lobes, and (3) the γ lobe and heel (a lateral projection formed by a hairpin turn of some of the peduncle fibers). All of the markers we have examined are consistent with these three sets. Previous Golgi studies demonstrate that each mushroom body cell projects one axon that branches into a dorsal lobe and a medial lobe, or one unbranched axon that projects medially. Taken together with the lobe sets listed above, we propose that there are three major projection configurations of mushroom body cell axons: (1) one branch in the α and one in the β lobe, (2) one branch in the α′ and one in the β′ lobe, and (3) one unbranched axon projecting to the heel and the γ lobe. The fact that these neuron types exhibit differential expression levels of a number of mushroom body genes suggests that they may have corresponding functional differences. These functions may be conserved in the larvae, as several of these genes were expressed in larval and embryonic mushroom bodies as well. The basic mushroom body structure, including the denritic calyx, peduncle, and lobes, was already

  6. Upper Palaeolithic Siberian genome reveals dual ancestry of Native Americans.

    PubMed

    Raghavan, Maanasa; Skoglund, Pontus; Graf, Kelly E; Metspalu, Mait; Albrechtsen, Anders; Moltke, Ida; Rasmussen, Simon; Stafford, Thomas W; Orlando, Ludovic; Metspalu, Ene; Karmin, Monika; Tambets, Kristiina; Rootsi, Siiri; Mägi, Reedik; Campos, Paula F; Balanovska, Elena; Balanovsky, Oleg; Khusnutdinova, Elza; Litvinov, Sergey; Osipova, Ludmila P; Fedorova, Sardana A; Voevoda, Mikhail I; DeGiorgio, Michael; Sicheritz-Ponten, Thomas; Brunak, Søren; Demeshchenko, Svetlana; Kivisild, Toomas; Villems, Richard; Nielsen, Rasmus; Jakobsson, Mattias; Willerslev, Eske

    2014-01-02

    The origins of the First Americans remain contentious. Although Native Americans seem to be genetically most closely related to east Asians, there is no consensus with regard to which specific Old World populations they are closest to. Here we sequence the draft genome of an approximately 24,000-year-old individual (MA-1), from Mal'ta in south-central Siberia, to an average depth of 1×. To our knowledge this is the oldest anatomically modern human genome reported to date. The MA-1 mitochondrial genome belongs to haplogroup U, which has also been found at high frequency among Upper Palaeolithic and Mesolithic European hunter-gatherers, and the Y chromosome of MA-1 is basal to modern-day western Eurasians and near the root of most Native American lineages. Similarly, we find autosomal evidence that MA-1 is basal to modern-day western Eurasians and genetically closely related to modern-day Native Americans, with no close affinity to east Asians. This suggests that populations related to contemporary western Eurasians had a more north-easterly distribution 24,000 years ago than commonly thought. Furthermore, we estimate that 14 to 38% of Native American ancestry may originate through gene flow from this ancient population. This is likely to have occurred after the divergence of Native American ancestors from east Asian ancestors, but before the diversification of Native American populations in the New World. Gene flow from the MA-1 lineage into Native American ancestors could explain why several crania from the First Americans have been reported as bearing morphological characteristics that do not resemble those of east Asians. Sequencing of another south-central Siberian, Afontova Gora-2 dating to approximately 17,000 years ago, revealed similar autosomal genetic signatures as MA-1, suggesting that the region was continuously occupied by humans throughout the Last Glacial Maximum. Our findings reveal that western Eurasian genetic signatures in modern-day Native

  7. Bahamian speleothems reveal Atlantic climate variability during Heinrich Events

    NASA Astrophysics Data System (ADS)

    Arienzo, M. M.; Swart, P. K.; Broad, K.; Clement, A. C.; Eisenhauer, A.; Kakuk, B.

    2010-12-01

    During the last glacial period there is confounding evidence for global millennial scale variability in climate, dominated by Heinrich events and Dansgaard-Oeschger (D/O) events. These events have been documented in the ice core records, deep-sea sediment records and speleothems. Speleothem records have been studied from diverse localities such as South and Central America, Continental United States, Europe, and China, however, there is a significant lack of paleoclimate data from the subtropical Atlantic. Our analyses of stalagmites from the Bahamas reveal that Heinrich events are preserved in the geochemical signature of our samples. To date, over 15 stalagmites have been collected and dated from Blue Holes in the Bahamas. Currently submerged, the speleothems are collected using advanced diving technologies at depths ranging from 10-40 meters below sea level. Sample DC-09 was collected at 16.5 meters below sea level from Dan’s Cave, Abaco Island, Bahamas and was forming from approximately 13,700 to 30,000 ybp, determined from U/Th age dates. Sample DC-14 was collected at 23.5 meters below sea level from the same cave and was dated from 13,800 to 54,000 ybp. These samples provide a continuous record and replicate records from the same cave aid in the interpretation of the geochemical data. These samples have been analyzed for stable carbon and oxygen isotopes as well as trace elements at a 20 μm resolution. Preliminary analysis reveals enrichment in the carbon and oxygen isotope values with amplitudes as large as 4.5‰ associated with Heinrich events. This reflects a change from relatively arid to wetter conditions, which occur over periods as short as 50 years. When comparing the record from DC-09 to DC-14, DC-09 consists of a greater C and O change associated with each Heinrich Event. This is possibly driven in part by the differences in depth at which the samples were forming. There is a greater amount of material overlying the deeper sample, therefore

  8. Crystallographic and spectroscopic snapshots reveal a dehydrogenase in action

    DOE PAGES

    Huo, Lu; Davis, Ian; Liu, Fange; ...

    2015-01-07

    Aldehydes are ubiquitous intermediates in metabolic pathways and their innate reactivity can often make them quite unstable. There are several aldehydic intermediates in the metabolic pathway for tryptophan degradation that can decay into neuroactive compounds that have been associated with numerous neurological diseases. An enzyme of this pathway, 2-aminomuconate-6-semialdehyde dehydrogenase, is responsible for ‘disarming’ the final aldehydic intermediate. Here we show the crystal structures of a bacterial analogue enzyme in five catalytically relevant forms: resting state, one binary and two ternary complexes, and a covalent, thioacyl intermediate. We also report the crystal structures of a tetrahedral, thiohemiacetal intermediate, a thioacylmore » intermediate and an NAD+-bound complex from an active site mutant. These covalent intermediates are characterized by single-crystal and solution-state electronic absorption spectroscopy. The crystal structures reveal that the substrate undergoes an E/Z isomerization at the enzyme active site before an sp3-to-sp2 transition during enzyme-mediated oxidation.« less

  9. Statistical universals reveal the structures and functions of human music.

    PubMed

    Savage, Patrick E; Brown, Steven; Sakai, Emi; Currie, Thomas E

    2015-07-21

    Music has been called "the universal language of mankind." Although contemporary theories of music evolution often invoke various musical universals, the existence of such universals has been disputed for decades and has never been empirically demonstrated. Here we combine a music-classification scheme with statistical analyses, including phylogenetic comparative methods, to examine a well-sampled global set of 304 music recordings. Our analyses reveal no absolute universals but strong support for many statistical universals that are consistent across all nine geographic regions sampled. These universals include 18 musical features that are common individually as well as a network of 10 features that are commonly associated with one another. They span not only features related to pitch and rhythm that are often cited as putative universals but also rarely cited domains including performance style and social context. These cross-cultural structural regularities of human music may relate to roles in facilitating group coordination and cohesion, as exemplified by the universal tendency to sing, play percussion instruments, and dance to simple, repetitive music in groups. Our findings highlight the need for scientists studying music evolution to expand the range of musical cultures and musical features under consideration. The statistical universals we identified represent important candidates for future investigation.

  10. Initiation process of a thrust fault revealed by analog experiments

    NASA Astrophysics Data System (ADS)

    Yamada, Yasuhiro; Dotare, Tatsuya; Adam, Juergen; Hori, Takane; Sakaguchi, Hide

    2016-04-01

    We conducted 2D (cross-sectional) analog experiments with dry sand using a high resolution digital image correlation (DIC) technique to reveal initiation process of a thrust fault in detail, and identified a number of "weak shear bands" and minor uplift prior to the thrust initiation. The observations suggest that the process can be divided into three stages. Stage 1: characterized by a series of abrupt and short-lived weak shear bands at the location where the thrust will be generated later. Before initiation of the fault, the area to be the hanging wall starts to uplift. Stage 2: defined by the generation of the new thrust and its active displacement. The location of the new thrust seems to be constrained by its associated back-thrust, produced at the foot of the surface slope (by the previous thrust). The activity of the previous thrust turns to zero once the new thrust is generated, but the timing of these two events is not the same. Stage 3: characterized by a constant displacement along the (new) thrust. Similar minor shear bands can be seen in the toe area of the Nankai accretionary prism, SW Japan and we can correlate the along-strike variations in seismic profiles to the model results that show the characteristic features in each thrust development stage.

  11. Genomic profiling reveals mutational landscape in parathyroid carcinomas

    PubMed Central

    Bellizzi, Justin; Lau, Chun Yee; Moe, Aye S.; Strahl, Maya; Newman, Leah C.; Fink, Marc Y.; Antipin, Yevgeniy; Yu, Willie; Stevenson, Mark; Cavaco, Branca M.; Thakker, Rajesh V.; Morreau, Hans; Schadt, Eric E.; Sebra, Robert; Li, Shuyu D.

    2017-01-01

    Parathyroid carcinoma (PC) is an extremely rare malignancy lacking effective therapeutic intervention. We generated and analyzed whole-exome sequencing data from 17 patients to identify somatic and germline genetic alterations. A panel of selected genes was sequenced in a 7-tumor expansion cohort. We show that 47% (8 of 17) of the tumors harbor somatic mutations in the CDC73 tumor suppressor, with germline inactivating variants in 4 of the 8 patients. The PI3K/AKT/mTOR pathway was altered in 21% of the 24 cases, revealing a major oncogenic pathway in PC. We observed CCND1 amplification in 29% of the 17 patients, and a previously unreported recurrent mutation in putative kinase ADCK1. We identified the first sporadic PCs with somatic mutations in the Wnt canonical pathway, complementing previously described epigenetic mechanisms mediating Wnt activation. This is the largest genomic sequencing study of PC, and represents major progress toward a full molecular characterization of this rare malignancy to inform improved and individualized treatments. PMID:28352668

  12. Phosphoproteomic Analysis Reveals Regulatory Mechanisms at the Kidney Filtration Barrier

    PubMed Central

    Rinschen, Markus M.; Wu, Xiongwu; König, Tim; Pisitkun, Trairak; Hagmann, Henning; Pahmeyer, Caroline; Lamkemeyer, Tobias; Kohli, Priyanka; Schnell, Nicole; Schermer, Bernhard; Dryer, Stuart; Brooks, Bernard R.; Beltrao, Pedro; Krueger, Marcus

    2014-01-01

    Diseases of the kidney filtration barrier are a leading cause of ESRD. Most disorders affect the podocytes, polarized cells with a limited capacity for self-renewal that require tightly controlled signaling to maintain their integrity, viability, and function. Here, we provide an atlas of in vivo phosphorylated, glomerulus-expressed proteins, including podocyte-specific gene products, identified in an unbiased tandem mass spectrometry–based approach. We discovered 2449 phosphorylated proteins corresponding to 4079 identified high-confidence phosphorylated residues and performed a systematic bioinformatics analysis of this dataset. We discovered 146 phosphorylation sites on proteins abundantly expressed in podocytes. The prohibitin homology domain of the slit diaphragm protein podocin contained one such site, threonine 234 (T234), located within a phosphorylation motif that is mutated in human genetic forms of proteinuria. The T234 site resides at the interface of podocin dimers. Free energy calculation through molecular dynamic simulations revealed a role for T234 in regulating podocin dimerization. We show that phosphorylation critically regulates formation of high molecular weight complexes and that this may represent a general principle for the assembly of proteins containing prohibitin homology domains. PMID:24511133

  13. Metagenomics reveals flavour metabolic network of cereal vinegar microbiota.

    PubMed

    Wu, Lin-Huan; Lu, Zhen-Ming; Zhang, Xiao-Juan; Wang, Zong-Min; Yu, Yong-Jian; Shi, Jin-Song; Xu, Zheng-Hong

    2017-04-01

    Multispecies microbial community formed through centuries of repeated batch acetic acid fermentation (AAF) is crucial for the flavour quality of traditional vinegar produced from cereals. However, the metabolism to generate and/or formulate the essential flavours by the multispecies microbial community is hardly understood. Here we used metagenomic approach to clarify in situ metabolic network of key microbes responsible for flavour synthesis of a typical cereal vinegar, Zhenjiang aromatic vinegar, produced by solid-state fermentation. First, we identified 3 organic acids, 7 amino acids, and 20 volatiles as dominant vinegar metabolites. Second, we revealed taxonomic and functional composition of the microbiota by metagenomic shotgun sequencing. A total of 86 201 predicted protein-coding genes from 35 phyla (951 genera) were involved in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of Metabolism (42.3%), Genetic Information Processing (28.3%), and Environmental Information Processing (10.1%). Furthermore, a metabolic network for substrate breakdown and dominant flavour formation in vinegar microbiota was constructed, and microbial distribution discrepancy in different metabolic pathways was charted. This study helps elucidating different metabolic roles of microbes during flavour formation in vinegar microbiota.

  14. Family level phylogenies reveal modes of macroevolution in RNA viruses

    PubMed Central

    Kitchen, Andrew; Shackelton, Laura A.; Holmes, Edward C.

    2011-01-01

    Despite advances in understanding the patterns and processes of microevolution in RNA viruses, little is known about the determinants of viral diversification at the macroevolutionary scale. In particular, the processes by which viral lineages assigned as different “species” are generated remain largely uncharacterized. To address this issue, we use a robust phylogenetic approach to analyze patterns of lineage diversification in five representative families of RNA viruses. We ask whether the process of lineage diversification primarily occurs when viruses infect new host species, either through cross-species transmission or codivergence, and which are defined here as analogous to allopatric speciation in animals, or by acquiring new niches within the same host species, analogous to sympatric speciation. By mapping probable primary host species onto family level viral phylogenies, we reveal a strong clustering among viral lineages that infect groups of closely related host species. Although this is consistent with lineage diversification within individual hosts, we argue that this pattern more likely represents strong biases in our knowledge of viral biodiversity, because we also find that better-sampled human viruses rarely cluster together. Hence, although closely related viruses tend to infect related host species, it is unlikely that they often infect the same host species, such that evolutionary constraints hinder lineage diversification within individual host species. We conclude that the colonization of new but related host species may represent the principle mode of macroevolution in RNA viruses. PMID:21173251

  15. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism

    NASA Astrophysics Data System (ADS)

    Krause, David W.; Hoffmann, Simone; Wible, John R.; Kirk, E. Christopher; Schultz, Julia A.; von Koenigswald, Wighart; Groenke, Joseph R.; Rossie, James B.; O'Connor, Patrick M.; Seiffert, Erik R.; Dumont, Elizabeth R.; Holloway, Waymon L.; Rogers, Raymond R.; Rahantarisoa, Lydia J.; Kemp, Addison D.; Andriamialison, Haingoson

    2014-11-01

    Previously known only from isolated teeth and lower jaw fragments recovered from the Cretaceous and Palaeogene of the Southern Hemisphere, the Gondwanatheria constitute the most poorly known of all major mammaliaform radiations. Here we report the discovery of the first skull material of a gondwanatherian, a complete and well-preserved cranium from Upper Cretaceous strata in Madagascar that we assign to a new genus and species. Phylogenetic analysis strongly supports its placement within Gondwanatheria, which are recognized as monophyletic and closely related to multituberculates, an evolutionarily successful clade of Mesozoic mammals known almost exclusively from the Northern Hemisphere. The new taxon is the largest known mammaliaform from the Mesozoic of Gondwana. Its craniofacial anatomy reveals that it was herbivorous, large-eyed and agile, with well-developed high-frequency hearing and a keen sense of smell. The cranium exhibits a mosaic of primitive and derived features, the disparity of which is extreme and probably reflective of a long evolutionary history in geographic isolation.

  16. Revealing Transcriptome Landscape of Mouse Spermatogonial Cells by Tiling Microarray

    PubMed Central

    Lee, Tin-Lap.; Rennert, Owen M.; Chan, Wai-Yee.

    2014-01-01

    Summary Spermatogenesis is a highly regulated developmental process by which spermatogonia develop into mature spermatozoa. This process involves many testis- or male germ cell-specific events through tightly regulated gene expression programs. In the past decade the advent of microarray technologies has allowed functional genomic studies of male germ cell development, resulting in the identification of genes governing various processes. A major limitation with conventional gene expression microarray is that there is a bias from gene probe design. The gene probes for expression microarrays are usually represented by a small number probes located at the 3’ end of a transcirpt. Tiling microarrays eliminate such issue by interrogating the genome in an unbiased fashion through probes tiled for the entire genome. These arrays provide a higher genomic resolution and allow identification of novel transcripts. To reveal the complexity of the genomic landscape of developing male germ cells, we applied tiling microarray to evaluate the transcriptome in spermatogonial cells. Over 50% of the mouse and rat genome are expressed during testicular development. More than 47% of transcripts are uncharacterized. The results suggested the transcription machinery in spermaotogonial cells are more complex than previously envisioned. PMID:22144238

  17. Mechanics of Viral Chromatin Reveals the Pressurization of Human Adenovirus.

    PubMed

    Ortega-Esteban, Alvaro; Condezo, Gabriela N; Pérez-Berná, Ana J; Chillón, Miguel; Flint, S Jane; Reguera, David; San Martín, Carmen; de Pablo, Pedro J

    2015-11-24

    Tight confinement of naked genomes within some viruses results in high internal pressure that facilitates their translocation into the host. Adenovirus, however, encodes histone-like proteins that associate with its genome resulting in a confined DNA-protein condensate (core). Cleavage of these proteins during maturation decreases core condensation and primes the virion for proper uncoating via unidentified mechanisms. Here we open individual, mature and immature adenovirus cages to directly probe the mechanics of their chromatin-like cores. We find that immature cores are more rigid than the mature ones, unveiling a mechanical signature of their condensation level. Conversely, intact mature particles demonstrate more rigidity than immature or empty ones. DNA-condensing polyamines revert the mechanics of mature capsid and cores to near-immature values. The combination of these experiments reveals the pressurization of adenovirus particles induced by maturation. We estimate a pressure of ∼30 atm by continuous elasticity, which is corroborated by modeling the adenovirus mini-chromosome as a confined compact polymer. We propose this pressurization as a mechanism that facilitates initiating the stepwise disassembly of the mature particle, enabling its escape from the endosome and final genome release at the nuclear pore.

  18. Widespread distribution of encapsulin nanocompartments reveals functional diversity.

    PubMed

    Giessen, Tobias W; Silver, Pamela A

    2017-03-06

    Cells organize and regulate their metabolism via membrane- or protein-bound organelles. In this way, incompatible processes can be spatially separated and controlled. In prokaryotes, protein-based compartments are used to sequester harmful reactions and store useful compounds. These protein compartments play key roles in various metabolic and ecological processes, ranging from iron homeostasis to carbon fixation. One of the newest types of protein organelle are encapsulin nanocompartments. They are able to encapsulate specific protein cargo and are proposed to be involved in redox-related processes. We identified more than 900 putative encapsulin systems in bacterial and archaeal genomes. Encapsulins can be found in fifteen bacterial and two archaeal phyla. Our analysis reveals one new capsid type and nine previously unknown cargo proteins targeted to the interior of encapsulins. We experimentally characterize three newly identified encapsulin systems and illustrate their probable involvement in iron mineralization, oxidative and nitrosative stress resistance and anaerobic ammonium oxidation, a process responsible for 30% of the nitrogen lost from the oceans.

  19. Next generation sequencing in sporadic retinoblastoma patients reveals somatic mosaicism.

    PubMed

    Amitrano, Sara; Marozza, Annabella; Somma, Serena; Imperatore, Valentina; Hadjistilianou, Theodora; De Francesco, Sonia; Toti, Paolo; Galimberti, Daniela; Meloni, Ilaria; Cetta, Francesco; Piu, Pietro; Di Marco, Chiara; Dosa, Laura; Lo Rizzo, Caterina; Carignani, Giulia; Mencarelli, Maria Antonietta; Mari, Francesca; Renieri, Alessandra; Ariani, Francesca

    2015-11-01

    In about 50% of sporadic cases of retinoblastoma, no constitutive RB1 mutations are detected by conventional methods. However, recent research suggests that, at least in some of these cases, there is somatic mosaicism with respect to RB1 normal and mutant alleles. The increased availability of next generation sequencing improves our ability to detect the exact percentage of patients with mosaicism. Using this technology, we re-tested a series of 40 patients with sporadic retinoblastoma: 10 of them had been previously classified as constitutional heterozygotes, whereas in 30 no RB1 mutations had been found in lymphocytes. In 3 of these 30 patients, we have now identified low-level mosaic variants, varying in frequency between 8 and 24%. In 7 out of the 10 cases previously classified as heterozygous from testing blood cells, we were able to test additional tissues (ocular tissues, urine and/or oral mucosa): in three of them, next generation sequencing has revealed mosaicism. Present results thus confirm that a significant fraction (6/40; 15%) of sporadic retinoblastoma cases are due to postzygotic events and that deep sequencing is an efficient method to unambiguously distinguish mosaics. Re-testing of retinoblastoma patients through next generation sequencing can thus provide new information that may have important implications with respect to genetic counseling and family care.

  20. Nicotinamide riboside kinase structures reveal new pathways to NAD+.

    PubMed

    Tempel, Wolfram; Rabeh, Wael M; Bogan, Katrina L; Belenky, Peter; Wojcik, Marzena; Seidle, Heather F; Nedyalkova, Lyudmila; Yang, Tianle; Sauve, Anthony A; Park, Hee-Won; Brenner, Charles

    2007-10-02

    The eukaryotic nicotinamide riboside kinase (Nrk) pathway, which is induced in response to nerve damage and promotes replicative life span in yeast, converts nicotinamide riboside to nicotinamide adenine dinucleotide (NAD+) by phosphorylation and adenylylation. Crystal structures of human Nrk1 bound to nucleoside and nucleotide substrates and products revealed an enzyme structurally similar to Rossmann fold metabolite kinases and allowed the identification of active site residues, which were shown to be essential for human Nrk1 and Nrk2 activity in vivo. Although the structures account for the 500-fold discrimination between nicotinamide riboside and pyrimidine nucleosides, no enzyme feature was identified to recognize the distinctive carboxamide group of nicotinamide riboside. Indeed, nicotinic acid riboside is a specific substrate of human Nrk enzymes and is utilized in yeast in a novel biosynthetic pathway that depends on Nrk and NAD+ synthetase. Additionally, nicotinic acid riboside is utilized in vivo by Urh1, Pnp1, and Preiss-Handler salvage. Thus, crystal structures of Nrk1 led to the identification of new pathways to NAD+.

  1. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    DOE PAGES

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; ...

    2015-12-17

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternarymore » structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.« less

  2. Parallel Selection Revealed by Population Sequencing in Chicken

    PubMed Central

    Qanbari, Saber; Seidel, Michael; Strom, Tim-Mathias; Mayer, Klaus F.X.; Preisinger, Ruedi; Simianer, Henner

    2015-01-01

    Human-driven selection during domestication and subsequent breed formation has likely left detectable signatures within the genome of modern chicken. The elucidation of these signatures of selection is of interest from the perspective of evolutionary biology, and for identifying genes relevant to domestication and improvement that ultimately may help to further genetically improve this economically important animal. We used whole genome sequence data from 50 hens of commercial white (WL) and brown (BL) egg-laying chicken along with pool sequences of three meat-type chicken to perform a systematic screening of past selection in modern chicken. Evidence of positive selection was investigated in two steps. First, we explored evidence of parallel fixation in regions with overlapping elevated allele frequencies in replicated populations of layers and broilers, suggestive of selection during domestication or preimprovement ages. We confirmed parallel fixation in BCDO2 and TSHR genes and found four candidates including AGTR2, a gene heavily involved in “Ascites” in commercial birds. Next, we explored differentiated loci between layers and broilers suggestive of selection during improvement in chicken. This analysis revealed evidence of parallel differentiation in genes relevant to appearance and production traits exemplified with the candidate gene OPG, implicated in Osteoporosis, a disorder related to overconsumption of calcium in egg-laying hens. Our results illustrate the potential for population genetic techniques to identify genomic regions relevant to the phenotypes of importance to breeders. PMID:26568375

  3. Exceptional structured noncoding RNAs revealed by bacterial metagenome analysis.

    PubMed

    Weinberg, Zasha; Perreault, Jonathan; Meyer, Michelle M; Breaker, Ronald R

    2009-12-03

    Estimates of the total number of bacterial species indicate that existing DNA sequence databases carry only a tiny fraction of the total amount of DNA sequence space represented by this division of life. Indeed, environmental DNA samples have been shown to encode many previously unknown classes of proteins and RNAs. Bioinformatics searches of genomic DNA from bacteria commonly identify new noncoding RNAs (ncRNAs) such as riboswitches. In rare instances, RNAs that exhibit more extensive sequence and structural conservation across a wide range of bacteria are encountered. Given that large structured RNAs are known to carry out complex biochemical functions such as protein synthesis and RNA processing reactions, identifying more RNAs of great size and intricate structure is likely to reveal additional biochemical functions that can be achieved by RNA. We applied an updated computational pipeline to discover ncRNAs that rival the known large ribozymes in size and structural complexity or that are among the most abundant RNAs in bacteria that encode them. These RNAs would have been difficult or impossible to detect without examining environmental DNA sequences, indicating that numerous RNAs with extraordinary size, structural complexity, or other exceptional characteristics remain to be discovered in unexplored sequence space.

  4. Maximal Neighbor Similarity Reveals Real Communities in Networks

    PubMed Central

    Žalik, Krista Rizman

    2015-01-01

    An important problem in the analysis of network data is the detection of groups of densely interconnected nodes also called modules or communities. Community structure reveals functions and organizations of networks. Currently used algorithms for community detection in large-scale real-world networks are computationally expensive or require a priori information such as the number or sizes of communities or are not able to give the same resulting partition in multiple runs. In this paper we investigate a simple and fast algorithm that uses the network structure alone and requires neither optimization of pre-defined objective function nor information about number of communities. We propose a bottom up community detection algorithm in which starting from communities consisting of adjacent pairs of nodes and their maximal similar neighbors we find real communities. We show that the overall advantage of the proposed algorithm compared to the other community detection algorithms is its simple nature, low computational cost and its very high accuracy in detection communities of different sizes also in networks with blurred modularity structure consisting of poorly separated communities. All communities identified by the proposed method for facebook network and E-Coli transcriptional regulatory network have strong structural and functional coherence. PMID:26680448

  5. Proteomic Analysis of Hylocereus polyrhizus Reveals Metabolic Pathway Changes

    PubMed Central

    Hua, Qingzhu; Zhou, Qianjun; Gan, Susheng; Wu, Jingyu; Chen, Canbin; Li, Jiaqiang; Ye, Yaoxiong; Zhao, Jietang; Hu, Guibing; Qin, Yonghua

    2016-01-01

    Red dragon fruit or red pitaya (Hylocereus polyrhizus) is the only edible fruit that contains betalains. The color of betalains ranges from red and violet to yellow in plants. Betalains may also serve as an important component of health-promoting and disease-preventing functional food. Currently, the biosynthetic and regulatory pathways for betalain production remain to be fully deciphered. In this study, isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analyses were used to reveal the molecular mechanism of betalain biosynthesis in H. polyrhizus fruits at white and red pulp stages, respectively. A total of 1946 proteins were identified as the differentially expressed between the two samples, and 936 of them were significantly highly expressed at the red pulp stage of H. polyrhizus. RNA-seq and iTRAQ analyses showed that some transcripts and proteins were positively correlated; they belonged to “phenylpropanoid biosynthesis”, “tyrosine metabolism”, “flavonoid biosynthesis”, “ascorbate and aldarate metabolism”, “betalains biosynthesis” and “anthocyanin biosynthesis”. In betalains biosynthesis pathway, several proteins/enzymes such as polyphenol oxidase, CYP76AD3 and 4,5-dihydroxy-phenylalanine (DOPA) dioxygenase extradiol-like protein were identified. The present study provides a new insight into the molecular mechanism of the betalain biosynthesis at the posttranscriptional level. PMID:27690004

  6. Diagnostic phylogenetics reveals a new Porcine circovirus 2 cluster.

    PubMed

    Davies, Brendan; Wang, Xiong; Dvorak, Cheryl M T; Marthaler, Douglas; Murtaugh, Michael P

    2016-06-02

    Porcine circovirus 2 (PCV2) was prevalent in swine in the United States before PCV2-associated disease (PCVAD) appeared in 2006. Limited nucleotide sequencing of open reading frame 2 (ORF2) encoding capsid, the only structural protein, revealed the presence of two genotypes, PCV2a and PCV2b. Later, PCV2c and mutant PCV2b, or PCV2d, were also described. However, extensive PCV2 ORF2 sequence databases in veterinary diagnostic laboratories have not been analyzed systematically to determine the genetic diversity of field isolates. Here, we interrogated >1100 PCV2 ORF2 nucleotide sequences to assess population diversity and genetic variation. We detected a novel PCV2 genotype that is substantially different, primarily in ORF2, from all known PCV2. Notably, ORF2 contains a unique carboxyl terminal amino acid insertion resulting in a 238 amino acid ORF2. All other PCV2 ORF2 proteins are 233 or 234 aa in length. Phylogenetic analysis indicates that it is more ancient than other PCV2 genotypes. The findings demonstrate the value of analyzing routine diagnostic laboratory sequence databases in population genetic analyses of animal pathogens.

  7. Phenotypic Expression in Wheat Revealed Using FT-IR Microspectroscopy

    SciTech Connect

    Brewer, L.; Wetzel, D

    2009-01-01

    Wheat selected for cultivation through the centuries has a glume that is 'soft' instead of 'tough' as naturally occurring. In production, this is desirable because it enables mechanical threshing with efficient separation of kernel from the head of each stalk without damaging the kernel. FT-IR microspectroscopy provides chemically based, objective assessment of genetic expression by measuring the extent of genetic expression. In the Microbeam Molecular Spectroscopy Laboratory, Manhattan, KS, an imaging FT-IR microspectrometer with a detector array focused on the image plane was used to obtain spectral data from dissected glume specimens of nine tough and eleven soft wheat cultivars in a rectangular mapping pattern. With cellulose as the substrate, the extent of lignification is measurable from the ratio of the lignin (1508 cm{sup -1}) baseline adjusted band area to the representative cellulosic (1370 cm{sup -1}) band area. A distinction between soft and tough glumes is obtained in numerical terms. Using a band ratio minimizes variation due to thickness differences. While analyzing mapped sections of glume, care is taken to avoid tabulation of spectral data from vascular bundles. Inclusion of these data would to avoid tabulation of spectral data from vascular bundles. Inclusion of these data would bias the analysis toward the composition of highly lignified vascular bundles. Spatially resolved focal plane array FT-IR microspectroscopy reveals the extent of glume lignification that is coincident with the toughness trait. This enables breeders to rank the degree of lignin expression and discriminate between soft and tough breeding results.

  8. Modeling malaria genomics reveals transmission decline and rebound in Senegal.

    PubMed

    Daniels, Rachel F; Schaffner, Stephen F; Wenger, Edward A; Proctor, Joshua L; Chang, Hsiao-Han; Wong, Wesley; Baro, Nicholas; Ndiaye, Daouda; Fall, Fatou Ba; Ndiop, Medoune; Ba, Mady; Milner, Danny A; Taylor, Terrie E; Neafsey, Daniel E; Volkman, Sarah K; Eckhoff, Philip A; Hartl, Daniel L; Wirth, Dyann F

    2015-06-02

    To study the effects of malaria-control interventions on parasite population genomics, we examined a set of 1,007 samples of the malaria parasite Plasmodium falciparum collected in Thiès, Senegal between 2006 and 2013. The parasite samples were genotyped using a molecular barcode of 24 SNPs. About 35% of the samples grouped into subsets with identical barcodes, varying in size by year and sometimes persisting across years. The barcodes also formed networks of related groups. Analysis of 164 completely sequenced parasites revealed extensive sharing of genomic regions. In at least two cases we found first-generation recombinant offspring of parents whose genomes are similar or identical to genomes also present in the sample. An epidemiological model that tracks parasite genotypes can reproduce the observed pattern of barcode subsets. Quantification of likelihoods in the model strongly suggests a reduction of transmission from 2006-2010 with a significant rebound in 2012-2013. The reduced transmission and rebound were confirmed directly by incidence data from Thiès. These findings imply that intensive intervention to control malaria results in rapid and dramatic changes in parasite population genomics. The results also suggest that genomics combined with epidemiological modeling may afford prompt, continuous, and cost-effective tracking of progress toward malaria elimination.

  9. Crystallographic and spectroscopic snapshots reveal a dehydrogenase in action

    SciTech Connect

    Huo, Lu; Davis, Ian; Liu, Fange; Andi, Babak; Esaki, Shingo; Iwaki, Hiroaki; Hasegawa, Yoshie; Orville, Allen M.; Liu, Aimin

    2015-01-07

    Aldehydes are ubiquitous intermediates in metabolic pathways and their innate reactivity can often make them quite unstable. There are several aldehydic intermediates in the metabolic pathway for tryptophan degradation that can decay into neuroactive compounds that have been associated with numerous neurological diseases. An enzyme of this pathway, 2-aminomuconate-6-semialdehyde dehydrogenase, is responsible for ‘disarming’ the final aldehydic intermediate. Here we show the crystal structures of a bacterial analogue enzyme in five catalytically relevant forms: resting state, one binary and two ternary complexes, and a covalent, thioacyl intermediate. We also report the crystal structures of a tetrahedral, thiohemiacetal intermediate, a thioacyl intermediate and an NAD+-bound complex from an active site mutant. These covalent intermediates are characterized by single-crystal and solution-state electronic absorption spectroscopy. The crystal structures reveal that the substrate undergoes an E/Z isomerization at the enzyme active site before an sp3-to-sp2 transition during enzyme-mediated oxidation.

  10. Ancestral resurrection reveals evolutionary mechanisms of kinase plasticity

    PubMed Central

    Howard, Conor J; Hanson-Smith, Victor; Kennedy, Kristopher J; Miller, Chad J; Lou, Hua Jane; Johnson, Alexander D; Turk, Benjamin E; Holt, Liam J

    2014-01-01

    Protein kinases have evolved diverse specificities to enable cellular information processing. To gain insight into the mechanisms underlying kinase diversification, we studied the CMGC protein kinases using ancestral reconstruction. Within this group, the cyclin dependent kinases (CDKs) and mitogen activated protein kinases (MAPKs) require proline at the +1 position of their substrates, while Ime2 prefers arginine. The resurrected common ancestor of CDKs, MAPKs, and Ime2 could phosphorylate substrates with +1 proline or arginine, with preference for proline. This specificity changed to a strong preference for +1 arginine in the lineage leading to Ime2 via an intermediate with equal specificity for proline and arginine. Mutant analysis revealed that a variable residue within the kinase catalytic cleft, DFGx, modulates +1 specificity. Expansion of Ime2 kinase specificity by mutation of this residue did not cause dominant deleterious effects in vivo. Tolerance of cells to new specificities likely enabled the evolutionary divergence of kinases. DOI: http://dx.doi.org/10.7554/eLife.04126.001 PMID:25310241

  11. Proteomics Reveal Cochlin Deposits Associated with Glaucomatous Trabecular Meshwork* S

    PubMed Central

    Bhattacharya, Sanjoy K.; Rockwood, Edward J.; Smith, Scott D.; Bonilha, Vera L.; Crabb, John S.; Kuchtey, Rachel W.; Robertson, Nahid G.; Peachey, Neal S.; Morton, Cynthia C.; Crabb, John W.

    2006-01-01

    The etiology of primary open angle glaucoma, a leading cause of age-related blindness, remains poorly defined, although elevated intraocular pressure (IOP) contributes to the disease progression. To better understand the mechanisms causing elevated IOP from aqueous humor circulation, we pursued proteomic analyses of trabecular meshwork (TM) from glaucoma and age-matched control donors. These analyses demonstrated that Cochlin, a protein associated with deafness disorder DFNA9, is present in glaucomatous but absent in normal TM. Cochlin was also detected in TM from the glaucomatous DBA/2J mouse preceding elevated IOP but found to be absent in three other mouse lines that do not develop elevated IOP. Histochemical analyses revealed co-deposits of Cochlin and mucopolysaccharide in human TM around Schlemm’s canal, similar to that observed in the cochlea in DFNA9 deafness. Purified Cochlin was found to aggregate after sheer stress and to induce the aggregation of TM cells in vitro. Age-dependent in vivo increases in Cochlin were observed in glaucomatous TM, concomitant with a decrease in type II collagen, suggesting that Cochlin may disrupt the TM architecture and render components like collagen more susceptible to degradation and collapse. Overall, these observations suggest that Cochlin contributes to elevated IOP in primary open angle glaucoma through altered interactions within the TM extracellular matrix, resulting in cell aggregation, mucopolysaccharide deposition, and significant obstruction of the aqueous humor circulation. PMID:15579465

  12. Eukaryote culturomics of the gut reveals new species.

    PubMed

    Gouba, Nina; Raoult, Didier; Drancourt, Michel

    2014-01-01

    The repertoire of microeukaryotes in the human gut has been poorly explored, mainly in individuals living in northern hemisphere countries. We further explored this repertoire using PCR-sequencing and culture in seven individuals living in four tropical countries. A total of 41 microeukaryotes including 38 different fungal species and three protists were detected. Four fungal species, Davidiella tassiana, Davidiella sp., Corticiaceae sp., and Penicillium sp., were uniquely detected by culture; 27 fungal species were uniquely detected using PCR-sequencing and Candida albicans, Candida glabrata, Trichosporon asahii, Clavispora lusitaniae, Debaryomyces hansenii, Malassezia restricta, and Malassezia sp. were detected using both molecular and culture methods. Fourteen microeukaryotes were shared by the seven individuals, whereas 27 species were found in only one individual, including 11 species in Amazonia, nine species in Polynesia, five species in India, and two species in Senegal. These data support a worldwide distribution of Malassezia sp., Trichosporon sp., and Candida sp. in the gut mycobiome. Here, 13 fungal species and two protists, Stentor roeseli and Vorticella campanula, were observed for first time in the human gut. This study revealed a previously unsuspected diversity in the repertoire of human gut microeukaryotes, suggesting spots for further exploring this repertoire.

  13. Eukaryote Culturomics of the Gut Reveals New Species

    PubMed Central

    Gouba, Nina; Raoult, Didier; Drancourt, Michel

    2014-01-01

    The repertoire of microeukaryotes in the human gut has been poorly explored, mainly in individuals living in northern hemisphere countries. We further explored this repertoire using PCR-sequencing and culture in seven individuals living in four tropical countries. A total of 41 microeukaryotes including 38 different fungal species and three protists were detected. Four fungal species, Davidiella tassiana, Davidiella sp., Corticiaceae sp., and Penicillium sp., were uniquely detected by culture; 27 fungal species were uniquely detected using PCR-sequencing and Candida albicans, Candida glabrata, Trichosporon asahii, Clavispora lusitaniae, Debaryomyces hansenii, Malassezia restricta, and Malassezia sp. were detected using both molecular and culture methods. Fourteen microeukaryotes were shared by the seven individuals, whereas 27 species were found in only one individual, including 11 species in Amazonia, nine species in Polynesia, five species in India, and two species in Senegal. These data support a worldwide distribution of Malassezia sp., Trichosporon sp., and Candida sp. in the gut mycobiome. Here, 13 fungal species and two protists, Stentor roeseli and Vorticella campanula, were observed for first time in the human gut. This study revealed a previously unsuspected diversity in the repertoire of human gut microeukaryotes, suggesting spots for further exploring this repertoire. PMID:25210972

  14. Orientation processing mechanisms revealed by the plaid tilt illusion

    NASA Technical Reports Server (NTRS)

    Smith, S.; Wenderoth, P.; van der Zwan, R.

    2001-01-01

    The tilt after-effect (TAE) and tilt illusion (TI) have revealed a great deal about the nature of orientation coding of 1-dimensional (1D) lines and gratings. Comparatively little research however has addressed the mechanisms responsible for encoding the orientation of 2-dimensional (2D) plaid stimuli. A multi-stage model of edge detection has recently been proposed [Georgeson, M. A. (1998) Image & Vision Computing, 16(6-7), 389-405] to account for the perceived structure of a plaid stimulus that incorporates extraction of the zero-crossings (ZCs) of the plaid. Data is presented showing that the ZCs of a plaid inducing stimulus can interact with vertical grating test stimulus to induce a standard tilt illusion. However, by considering the second-order structure of a plaid rather than ZCs, it was shown that the perceived orientation of the vertical test grating results from the combination of orientation illusions due to the first- and second-order components of an inducing plaid. The data suggest that the mechanisms encoding the orientation of second-order contours are similar to, and interact directly with, those that encode first-order contours.

  15. Revealing biological information using data structuring and automated learning.

    PubMed

    Mohorianu, Irina; Moulton, Vincent

    2010-11-01

    The intermediary steps between a biological hypothesis, concretized in the input data, and meaningful results, validated using biological experiments, commonly employ bioinformatics tools. Starting with storage of the data and ending with a statistical analysis of the significance of the results, every step in a bioinformatics analysis has been intensively studied and the resulting methods and models patented. This review summarizes the bioinformatics patents that have been developed mainly for the study of genes, and points out the universal applicability of bioinformatics methods to other related studies such as RNA interference. More specifically, we overview the steps undertaken in the majority of bioinformatics analyses, highlighting, for each, various approaches that have been developed to reveal details from different perspectives. First we consider data warehousing, the first task that has to be performed efficiently, optimizing the structure of the database, in order to facilitate both the subsequent steps and the retrieval of information. Next, we review data mining, which occupies the central part of most bioinformatics analyses, presenting patents concerning differential expression, unsupervised and supervised learning. Last, we discuss how networks of interactions of genes or other players in the cell may be created, which help draw biological conclusions and have been described in several patents.

  16. Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium

    SciTech Connect

    Ma, Li Jun; van der Does, H. C.; Borkovich, Katherine A.; Coleman, Jeffrey J.; Daboussi, Marie-Jose; Di Pietro, Antonio; Dufresne, Marie; Freitag, Michael; Grabherr, Manfred; Henrissat, Bernard; Houterman, Petra M.; Kang, Seogchan; Shim, Won-Bo; Wolochuk, Charles; Xie, Xiaohui; Xu, Jin Rong; Antoniw, John; Baker, Scott E.; Bluhm, Burton H.; Breakspear, Andrew; Brown, Daren W.; Butchko, Robert A.; Chapman, Sinead; Coulson, Richard; Coutinho, Pedro M.; Danchin, Etienne G.; Diener, Andrew; Gale, Liane R.; Gardiner, Donald; Goff, Steven; Hammond-Kossack, Kim; Hilburn, Karen; Hua-Van, Aurelie; Jonkers, Wilfried; Kazan, Kemal; Kodira, Chinnappa D.; Koehrsen, Michael; Kumar, Lokesh; Lee, Yong Hwan; Li, Liande; Manners, John M.; Miranda-Saavedra, Diego; Mukherjee, Mala; Park, Gyungsoon; Park, Jongsun; Park, Sook Young; Proctor, Robert H.; Regev, Aviv; Ruiz-Roldan, M. C.; Sain, Divya; Sakthikumar, Sharadha; Sykes, Sean; Schwartz, David C.; Turgeon, Barbara G.; Wapinski, Ilan; Yoder, Olen; Young, Sarah; Zeng, Qiandong; Zhou, Shiguo; Galagan, James; Cuomo, Christina A.; Kistler, H. Corby; Rep, Martijn

    2010-03-18

    Fusarium species are among the most important phytopathogenic and toxigenic fungi, having significant impact on crop production and animal health. Distinctively, members of the F. oxysporum species complex exhibit wide host range but discontinuously distributed host specificity, reflecting remarkable genetic adaptability. To understand the molecular underpinnings of diverse phenotypic traits and their evolution in Fusarium, we compared the genomes of three economically important and phylogenetically related, yet phenotypically diverse plant-pathogenic species, F. graminearum, F. verticillioides and F. oxysporum f. sp. lycopersici. Our analysis revealed greatly expanded lineage-specific (LS) genomic regions in F. oxysporum that include four entire chromosomes, accounting for more than one-quarter of the genome. LS regions are rich in transposons and genes with distinct evolutionary profiles but related to pathogenicity. Experimentally, we demonstrate for the first time the transfer of two LS chromosomes between strains of F. oxysporum, resulting in the conversion of a non-pathogenic strain into a pathogen. Transfer of LS chromosomes between otherwise genetically isolated strains explains the polyphyletic origin of host specificity and the emergence of new pathogenic lineages in the F. oxysporum species complex, putting the evolution of fungal pathogenicity into a new perspective.

  17. Scurvy revealed by difficulty walking: three cases in young children.

    PubMed

    Kitcharoensakkul, Maleewan; Schulz, Christa G; Kassel, Rachel; Khanna, Geetika; Liang, Shannon; Ngwube, Alexander; Baszis, Kevin W; Hunstad, David A; White, Andrew J

    2014-06-01

    Scurvy is rare in developed countries but is known to cause lower-extremity pain and refusal to ambulate in children. Since the discovery of the link between scurvy and dietary deficiency of ascorbic acid, there has been a substantial decrease in its prevalence and recognition. Here we describe 3 cases of scurvy in young children presenting with difficulty walking. Only 1 of 3 patients had gingival lesions at the initial presentation. Two cases underwent an extensive evaluation for hematologic and rheumatologic diseases before the diagnosis of scurvy was made. Dietary histories eventually revealed that all 3 patients had sharply limited intake of fruits and vegetables secondary to oral aversion, and 1 patient had autism. Radiographic changes of long bones were observed in all patients. Interestingly, all patients had concomitant vitamin D deficiency. After replacement with vitamin C, all patients recovered and started to walk again with improved leg pain. These clinical manifestations and radiologic findings highlight the importance for rheumatologists to have a higher index of suspicion for scurvy in nonambulatory children.

  18. Marine viruses, a genetic reservoir revealed by targeted viromics

    PubMed Central

    Martínez, Joaquín Martínez; Swan, Brandon K; Wilson, William H

    2014-01-01

    Metagenomics has opened new windows on investigating viral diversity and functions. Viromic studies typically require large sample volumes and filtration through 0.2 μm pore-size filters, consequently excluding or under-sampling tailed and very large viruses. We have optimized a targeted viromic approach that employs fluorescence-activated sorting and whole genome amplification to produce dsDNA-enriched libraries from discrete viral populations from a 1-ml water sample. Using this approach on an environmental sample from the Patagonian Shelf, we produced three distinct libraries. One of the virus libraries was dominated (79.65% of sequences with known viral homology) by giant viruses from the Mimiviridae and Phycodnaviridae families, while the two other viromes were dominated by smaller phycodnaviruses, cyanophages and other bacteriophages. The estimated genotypic richness and diversity in our sorted viromes, with 52–163 estimated genotypes, was much lower than in previous virome reports. Fragment recruitment of metagenome reads to selected reference viral genomes yields high genome coverage, suggesting little amplification and sequencing bias against some genomic regions. These results underscore the value of our approach as an effective way to target and investigate specific virus groups. In particular, it will help reveal the diversity and abundance of giant viruses in marine ecosystems. PMID:24304671

  19. Directional postcopulatory sexual selection revealed by artificial insemination.

    PubMed

    Evans, Jonathan P; Zane, Lorenzo; Francescato, Samuela; Pilastro, Andrea

    2003-01-23

    Postcopulatory sexual selection comprises both sperm competition, where the sperm from different males compete for fertilization, and cryptic female choice, where females bias sperm use in favour of particular males. Despite intense current interest in both processes as potential agents of directional sexual selection, few studies have attributed the success of attractive males to events that occur exclusively after insemination. This is because the interactions between pre- and post-insemination episodes of sexual selection can be important sources of variation in paternity. The use of artificial insemination overcomes this difficulty because it controls for variation in male fertilization success attributable to the female's perception of male quality, as well as effects due to mating order and the relative contribution of sperm from competing males. Here, we adopt this technique and show that in guppies, when equal numbers of sperm from two males compete for fertilization, relatively colourful individuals achieve greater parentage than their less ornamented counterparts. This finding indicates that precopulatory female mating preferences can be reinforced exclusively through postcopulatory processes occurring at a physiological level. Our analysis also revealed that relatively small individuals were advantaged in sperm competition, suggesting a possible trade-off between sperm competitive ability and body growth.

  20. Artificial spatiotemporal touch inputs reveal complementary decoding in neocortical neurons

    PubMed Central

    Oddo, Calogero M.; Mazzoni, Alberto; Spanne, Anton; Enander, Jonas M. D.; Mogensen, Hannes; Bengtsson, Fredrik; Camboni, Domenico; Micera, Silvestro; Jörntell, Henrik

    2017-01-01

    Investigations of the mechanisms of touch perception and decoding has been hampered by difficulties in achieving invariant patterns of skin sensor activation. To obtain reproducible spatiotemporal patterns of activation of sensory afferents, we used an artificial fingertip equipped with an array of neuromorphic sensors. The artificial fingertip was used to transduce real-world haptic stimuli into spatiotemporal patterns of spikes. These spike patterns were delivered to the skin afferents of the second digit of rats via an array of stimulation electrodes. Combined with low-noise intra- and extracellular recordings from neocortical neurons in vivo, this approach provided a previously inaccessible high resolution analysis of the representation of tactile information in the neocortical neuronal circuitry. The results indicate high information content in individual neurons and reveal multiple novel neuronal tactile coding features such as heterogeneous and complementary spatiotemporal input selectivity also between neighboring neurons. Such neuronal heterogeneity and complementariness can potentially support a very high decoding capacity in a limited population of neurons. Our results also indicate a potential neuroprosthetic approach to communicate with the brain at a very high resolution and provide a potential novel solution for evaluating the degree or state of neurological disease in animal models. PMID:28374841

  1. Cytoplasmic dynamics reveals two modes of nucleoid-dependent mobility.

    PubMed

    Stylianidou, Stella; Kuwada, Nathan J; Wiggins, Paul A

    2014-12-02

    It has been proposed that forces resulting from the physical exclusion of macromolecules from the bacterial nucleoid play a central role in organizing the bacterial cell, yet this proposal has not been quantitatively tested. To investigate this hypothesis, we mapped the generic motion of large protein complexes in the bacterial cytoplasm through quantitative analysis of thousands of complete cell-cycle trajectories of fluorescently tagged ectopic MS2-mRNA complexes. We find the motion of these complexes in the cytoplasm is strongly dependent on their spatial position along the long axis of the cell, and that their dynamics are consistent with a quantitative model that requires only nucleoid exclusion and membrane confinement. This analysis also reveals that the nucleoid increases the mobility of MS2-mRNA complexes, resulting in a fourfold increase in diffusion coefficients between regions of the lowest and highest nucleoid density. These data provide strong quantitative support for two modes of nucleoid action: the widely accepted mechanism of nucleoid exclusion in organizing the cell and a newly proposed mode, in which the nucleoid facilitates rapid motion throughout the cytoplasm.

  2. NMR reveals a dynamic allosteric pathway in thrombin

    PubMed Central

    Handley, Lindsey D.; Fuglestad, Brian; Stearns, Kyle; Tonelli, Marco; Fenwick, R. Bryn; Markwick, Phineus R. L.; Komives, Elizabeth A.

    2017-01-01

    Although serine proteases are found ubiquitously in both eukaryotes and prokaryotes, and they comprise the largest of all of the peptidase families, their dynamic motions remain obscure. The backbone dynamics of the coagulation serine protease, apo-thrombin (S195M-thrombin), were compared to the substrate-bound form (PPACK-thrombin). R1, R2, 15N-{1H}NOEs, and relaxation dispersion NMR experiments were measured to capture motions across the ps to ms timescale. The ps-ns motions were not significantly altered upon substrate binding. The relaxation dispersion data revealed that apo-thrombin is highly dynamic, with μs-ms motions throughout the molecule. The region around the N-terminus of the heavy chain, the Na+-binding loop, and the 170 s loop, all of which are implicated in allosteric coupling between effector binding sites and the active site, were dynamic primarily in the apo-form. Most of the loops surrounding the active site become more ordered upon PPACK-binding, but residues in the N-terminal part of the heavy chain, the γ-loop, and anion-binding exosite 1, the main allosteric binding site, retain μs-ms motions. These residues form a dynamic allosteric pathway connecting the active site to the main allosteric site that remains in the substrate-bound form. PMID:28059082

  3. Effective Connectivity Reveals Strategy Differences in an Expert Calculator

    PubMed Central

    Minati, Ludovico; Sigala, Natasha

    2013-01-01

    Mathematical reasoning is a core component of cognition and the study of experts defines the upper limits of human cognitive abilities, which is why we are fascinated by peak performers, such as chess masters and mental calculators. Here, we investigated the neural bases of calendrical skills, i.e. the ability to rapidly identify the weekday of a particular date, in a gifted mental calculator who does not fall in the autistic spectrum, using functional MRI. Graph-based mapping of effective connectivity, but not univariate analysis, revealed distinct anatomical location of “cortical hubs” supporting the processing of well-practiced close dates and less-practiced remote dates: the former engaged predominantly occipital and medial temporal areas, whereas the latter were associated mainly with prefrontal, orbitofrontal and anterior cingulate connectivity. These results point to the effect of extensive practice on the development of expertise and long term working memory, and demonstrate the role of frontal networks in supporting performance on less practiced calculations, which incur additional processing demands. Through the example of calendrical skills, our results demonstrate that the ability to perform complex calculations is initially supported by extensive attentional and strategic resources, which, as expertise develops, are gradually replaced by access to long term working memory for familiar material. PMID:24086291

  4. Revealing the hidden structural phases of FeRh

    NASA Astrophysics Data System (ADS)

    Kim, Jinwoong; Ramesh, R.; Kioussis, Nicholas

    2016-11-01

    Ab initio electronic structure calculations reveal that tetragonal distortion has a dramatic effect on the relative stability of the various magnetic structures (C-, A-, G-, A'-AFM, and FM) of FeRh giving rise to a wide range of novel stable/metastable structures and magnetic phase transitions between these states. We predict that the cubic G-AFM structure, which was believed thus far to be the ground state, is metastable and that the tetragonally expanded G-AFM is the stable structure. The low energy barrier separating these states suggests phase coexistence at room temperature. We propose an A'-AFM phase to be the global ground state among all magnetic phases which arises from the strain-induced tuning of the exchange interactions. The results elucidate the underlying mechanism for the recent experimental findings of electric-field control of magnetic phase transition driven via tetragonal strain. The magnetic phase transitions open interesting prospects for exploiting strain engineering for the next-generation memory devices.

  5. Towards revealing the structure of bacterial inclusion bodies.

    PubMed

    Wang, Lei

    2009-01-01

    Protein aggregation is a widely observed phenomenon in human diseases, biopharmaceutical production, and biological research. Protein aggregates are generally classified as highly ordered, such as amyloid fibrils, or amorphous, such as bacterial inclusion bodies. Amyloid fibrils are elongated filaments with diameters of 6-12 nm, they are comprised of residue-specific cross-beta structure, and display characteristic properties, such as binding with amyloid-specific dyes. Amyloid fibrils are associated with dozens of human pathological conditions, including Alzheimer disease and prion diseases. Distinguished from amyloid fibrils, bacterial inclusion bodies display apparent amorphous morphology. Inclusion bodies are formed during high-level recombinant protein production, and formation of inclusion bodies is a major concern in biotechnology. Despite of the distinctive morphological difference, bacterial inclusion bodies have been found to have some amyloid-like properties, suggesting that they might contain structures similar to amyloid-like fibrils. Recent structural data further support this hypothesis, and this review summarizes the latest progress towards revealing the structural details of bacterial inclusion bodies.

  6. Artemin Crystal Structure Reveals Insights into Heparan Sulfate Binding

    SciTech Connect

    Silvian,L.; Jin, P.; Carmillo, P.; Boriack-Sjodin, P.; Pelletier, C.; Rushe, M.; Gong, B.; Sah, D.; Pepinsky, B.; Rossomando, A.

    2006-01-01

    Artemin (ART) promotes the growth of developing peripheral neurons by signaling through a multicomponent receptor complex comprised of a transmembrane tyrosine kinase receptor (cRET) and a specific glycosylphosphatidylinositol-linked co-receptor (GFR{alpha}3). Glial cell line-derived neurotrophic factor (GDNF) signals through a similar ternary complex but requires heparan sulfate proteoglycans (HSPGs) for full activity. HSPG has not been demonstrated as a requirement for ART signaling. We crystallized ART in the presence of sulfate and solved its structure by isomorphous replacement. The structure reveals ordered sulfate anions bound to arginine residues in the pre-helix and amino-terminal regions that were organized in a triad arrangement characteristic of heparan sulfate. Three residues in the pre-helix were singly or triply substituted with glutamic acid, and the resulting proteins were shown to have reduced heparin-binding affinity that is partly reflected in their ability to activate cRET. This study suggests that ART binds HSPGs and identifies residues that may be involved in HSPG binding.

  7. Voluminous volcanism on early mars revealed in valles marineris

    USGS Publications Warehouse

    McEwen, A.S.; Malin, M.C.; Carr, M.H.; Hartmann, W.K.

    1999-01-01

    The relative rates and importance of impact cratering, volcanism, erosion, and the deposition of sediments to the early geological history of Mars are poorly known. That history is recorded in the upper crust of the planet, which is best exposed along the 4,000km-long canyon system called Valles Marineris. Previous studies of the stratigraphy of this region have assumed that it consists of megabreccia and fractured bedrock resulting from impacts, overlain by or interbedded with relatively thin layers of lava, and with the layering restricted to the uppermost level of the crust. Here we report new high-resolution images that reveal ubiquitous horizontal layering to depths of at least 8 km in the canyons. Megabreccia should be only coarsely layered and fractured bedrock should be unlayered, so these observations indicate that volcanic or sedimentary processes were much more important in early martian history than previously believed. Morphological and compositional data suggest that the layers were formed mainly by volcanic flood lavas. Mars was therefore probably very volcanically active during at least the first billion years and after the period when the heaviest impact bombardment had ended.

  8. Proteomics Analysis Reveals Previously Uncharacterized Virulence Factors in Vibrio proteolyticus

    PubMed Central

    Ray, Ann; Kinch, Lisa N.; de Souza Santos, Marcela; Grishin, Nick V.

    2016-01-01

    ABSTRACT Members of the genus Vibrio include many pathogens of humans and marine animals that share genetic information via horizontal gene transfer. Hence, the Vibrio pan-genome carries the potential to establish new pathogenic strains by sharing virulence determinants, many of which have yet to be characterized. Here, we investigated the virulence properties of Vibrio proteolyticus, a Gram-negative marine bacterium previously identified as part of the Vibrio consortium isolated from diseased corals. We found that V. proteolyticus causes actin cytoskeleton rearrangements followed by cell lysis in HeLa cells in a contact-independent manner. In search of the responsible virulence factor involved, we determined the V. proteolyticus secretome. This proteomics approach revealed various putative virulence factors, including active type VI secretion systems and effectors with virulence toxin domains; however, these type VI secretion systems were not responsible for the observed cytotoxic effects. Further examination of the V. proteolyticus secretome led us to hypothesize and subsequently demonstrate that a secreted hemolysin, belonging to a previously uncharacterized clan of the leukocidin superfamily, was the toxin responsible for the V. proteolyticus-mediated cytotoxicity in both HeLa cells and macrophages. Clearly, there remains an armory of yet-to-be-discovered virulence factors in the Vibrio pan-genome that will undoubtedly provide a wealth of knowledge on how a pathogen can manipulate host cells. PMID:27460800

  9. Acoustic telemetry reveals cryptic residency of whale sharks.

    PubMed

    Cagua, E Fernando; Cochran, Jesse E M; Rohner, Christoph A; Prebble, Clare E M; Sinclair-Taylor, Tane H; Pierce, Simon J; Berumen, Michael L

    2015-04-01

    Although whale sharks (Rhincodon typus) have been documented to move thousands of kilometres, they are most frequently observed at a few predictable seasonal aggregation sites. The absence of sharks at the surface during visual surveys has led to the assumption that sharks disperse to places unknown during the long 'off-seasons' at most of these locations. Here we compare 2 years of R. typus visual sighting records from Mafia Island in Tanzania to concurrent acoustic telemetry of tagged individuals. Sightings revealed a clear seasonal pattern with a peak between October and February and no sharks observed at other times. By contrast, acoustic telemetry demonstrated year-round residency of R. typus. The sharks use a different habitat in the off-season, swimming deeper and further away from shore, presumably in response to prey distributions. This behavioural change reduces the sharks' visibility, giving the false impression that they have left the area. We demonstrate, for the first time to our knowledge, year-round residency of unprovisioned, individual R. typus at an aggregation site, and highlight the importance of using multiple techniques to study the movement ecology of marine megafauna.

  10. Distributed neural system for emotional intelligence revealed by lesion mapping.

    PubMed

    Barbey, Aron K; Colom, Roberto; Grafman, Jordan

    2014-03-01

    Cognitive neuroscience has made considerable progress in understanding the neural architecture of human intelligence, identifying a broadly distributed network of frontal and parietal regions that support goal-directed, intelligent behavior. However, the contributions of this network to social and emotional aspects of intellectual function remain to be well characterized. Here we investigated the neural basis of emotional intelligence in 152 patients with focal brain injuries using voxel-based lesion-symptom mapping. Latent variable modeling was applied to obtain measures of emotional intelligence, general intelligence and personality from the Mayer, Salovey, Caruso Emotional Intelligence Test (MSCEIT), the Wechsler Adult Intelligence Scale and the Neuroticism-Extroversion-Openness Inventory, respectively. Regression analyses revealed that latent scores for measures of general intelligence and personality reliably predicted latent scores for emotional intelligence. Lesion mapping results further indicated that these convergent processes depend on a shared network of frontal, temporal and parietal brain regions. The results support an integrative framework for understanding the architecture of executive, social and emotional processes and make specific recommendations for the interpretation and application of the MSCEIT to the study of emotional intelligence in health and disease.

  11. Historical Reconstruction Reveals Recovery in Hawaiian Coral Reefs

    PubMed Central

    Kittinger, John N.; Pandolfi, John M.; Blodgett, Jonathan H.; Hunt, Terry L.; Jiang, Hong; Maly, Kepā; McClenachan, Loren E.; Schultz, Jennifer K.; Wilcox, Bruce A.

    2011-01-01

    Coral reef ecosystems are declining worldwide, yet regional differences in the trajectories, timing and extent of degradation highlight the need for in-depth regional case studies to understand the factors that contribute to either ecosystem sustainability or decline. We reconstructed social-ecological interactions in Hawaiian coral reef environments over 700 years using detailed datasets on ecological conditions, proximate anthropogenic stressor regimes and social change. Here we report previously undetected recovery periods in Hawaiian coral reefs, including a historical recovery in the MHI (∼AD 1400–1820) and an ongoing recovery in the NWHI (∼AD 1950–2009+). These recovery periods appear to be attributed to a complex set of changes in underlying social systems, which served to release reefs from direct anthropogenic stressor regimes. Recovery at the ecosystem level is associated with reductions in stressors over long time periods (decades+) and large spatial scales (>103 km2). Our results challenge conventional assumptions and reported findings that human impacts to ecosystems are cumulative and lead only to long-term trajectories of environmental decline. In contrast, recovery periods reveal that human societies have interacted sustainably with coral reef environments over long time periods, and that degraded ecosystems may still retain the adaptive capacity and resilience to recover from human impacts. PMID:21991311

  12. Knock-Out Models Reveal New Aquaporin Functions

    PubMed Central

    Verkman, Alan S.

    2013-01-01

    Knockout mice have been informative in the discovery of unexpected biological functions of aquaporins. Knockout mice have confirmed the predicted roles of aquaporins in transepithelial fluid transport, as in the urinary concentrating mechanism and glandular fluid secretion. A less obvious, though predictable role of aquaporins is in tissue swelling under stress, as in the brain in stroke, tumor and infection. Phenotype analysis of aquaporin knockout mice has revealed several unexpected cellular roles of aquaporins whose mechanisms are being elucidated. Aquaporins facilitate cell migration, as seen in aquaporin-dependent tumor angiogenesis and tumor metastasis, by a mechanism that may involve facilitated water transport in lamellipodia of migrating cells. The ‘aquaglyceroporins’, aquaporins that transport both glycerol and water, regulate glycerol content in epidermis, fat and other tissues, and lead to a multiplicity of interesting consequences of gene disruption including dry skin, resistance to skin carcinogenesis, impaired cell proliferation and altered fat metabolism. An even more surprising role of a mammalian aquaporin is in neural signal transduction in the central nervous system. The many roles of aquaporins might be exploited for clinical benefit by modulation of aquaporin expression/function – as diuretics, and in the treatment of brain swelling, glaucoma, epilepsy, obesity and cancer. PMID:19096787

  13. Tectonic deformation revealed in baldcypress trees at Reelfoot Lake, Tennessee

    SciTech Connect

    VanArsdale, R.; Stahle, D.; Cleaveland, M. )

    1991-07-01

    Tree-ring analyses of baldcypress (Taxodium distichum) from Reelfoot Lake, Tennessee, support historical accounts that the lake formed during the great New Madrid earthquakes of 1811--1812. Due to ground subsidence and permanent flooding all of the bottomland hardwood trees within the impounded area were killed. However, many water tolerant baldcypress survived, and hundreds of 200 to 800 year old baldcypress outline the positions of former stream channels drowned by the subsidence. Dendrochronological analyses of multiple cores from 21 baldcypress in the lake reveal several pronounced growth responses to the 1811--1812 earthquakes. These responses include a great surge in radial growth during the decade following the earthquakes and a permanent reduction in wood density beginning in 1812. These and other growth responses to the 1811--1912 earthquakes may allow us to determine if there have been other large earthquakes in the Reelfoot basin during the late Holocene and may help date the formation of other suspected sunk lands in the New Madrid seismic zone. 14 refs., 6 figs.

  14. Structure of the Angiotensin Receptor Revealed by Serial Femtosecond Crystallography

    DOE PAGES

    Zhang, Haitao; Unal, Hamiyet; Gati, Cornelius; ...

    2015-05-07

    We report that angiotensin II type 1 receptor (AT1R) is a G protein-coupled receptor that serves as a primary regulator for blood pressure maintenance. Although several anti-hypertensive drugs have been developed as AT1R blockers (ARBs), the structural basis for AT1R ligand-binding and regulation has remained elusive, mostly due to the difficulties of growing high quality crystals for structure determination using synchrotron radiation. By applying the recently developed method of serial femtosecond crystallography at an X-ray free-electron laser, we successfully determined the room-temperature crystal structure of the human AT1R in complex with its selective antagonist ZD7155 at 2.9 Å resolution. Themore » AT1R-ZD7155 complex structure revealed key structural features ofAT1R and critical interactions for ZD7155 binding. Finally, docking simulations of the clinically used ARBs into the AT1R structure further elucidated both the common and distinct binding modes for these anti-hypertensive drugs. Our results thereby provide fundamental insights into AT1R structure-function relationship and structure-based drug design.« less

  15. Structure of the Angiotensin Receptor Revealed by Serial Femtosecond Crystallography

    SciTech Connect

    Zhang, Haitao; Unal, Hamiyet; Gati, Cornelius; Han, Gye Won; Liu, Wei; Zatsepin, Nadia A.; James, Daniel; Wang, Dingjie; Nelson, Garrett; Weierstall, Uwe; Sawaya, Michael R.; Xu, Qingping; Messerschmidt, Marc; Williams, Garth J.; Boutet, Sébastien; Yefanov, Oleksandr M.; White, Thomas A.; Wang, Chong; Ishchenko, Andrii; Tirupula, Kalyan C.; Desnoyer, Russell; Coe, Jesse; Conrad, Chelsie E.; Fromme, Petra; Stevens, Raymond C.; Katritch, Vsevolod; Karnik, Sadashiva S.; Cherezov, Vadim

    2015-05-07

    We report that angiotensin II type 1 receptor (AT1R) is a G protein-coupled receptor that serves as a primary regulator for blood pressure maintenance. Although several anti-hypertensive drugs have been developed as AT1R blockers (ARBs), the structural basis for AT1R ligand-binding and regulation has remained elusive, mostly due to the difficulties of growing high quality crystals for structure determination using synchrotron radiation. By applying the recently developed method of serial femtosecond crystallography at an X-ray free-electron laser, we successfully determined the room-temperature crystal structure of the human AT1R in complex with its selective antagonist ZD7155 at 2.9 Å resolution. The AT1R-ZD7155 complex structure revealed key structural features ofAT1R and critical interactions for ZD7155 binding. Finally, docking simulations of the clinically used ARBs into the AT1R structure further elucidated both the common and distinct binding modes for these anti-hypertensive drugs. Our results thereby provide fundamental insights into AT1R structure-function relationship and structure-based drug design.

  16. Color-Shape Associations Revealed with Implicit Association Tests

    PubMed Central

    Chen, Na; Tanaka, Kanji; Watanabe, Katsumi

    2015-01-01

    Kandinsky proposed a correspondence theory that suggests associations between specific colors and shapes (i.e., circle-blue, square-red, triangle-yellow). Makin and Wuerger tested the theory using the Implicit Association Test (IAT) and did not find clear evidence for Kandinsky’s color-shape associations among British participants. In the present study, we first replicated the previous study among Japanese participants and found similar results to those of Makin and Wuerger, showing little support for Kandinsky’s theory. In the subsequent experiment, we tested another set of color-shape associations that had been revealed by using an explicit matching method (circle-red, square-blue, triangle-yellow) in Japanese participants. The IAT tests showed that response times were significantly faster when circle-red, square-blue, and triangle-yellow combinations were mapped onto the same response key, rather than different key combinations, indicating that these color-shape combinations were encoded. These results provide the first empirical evidence that color-shape associations can be measured by indirect behavioral methods, and in particular, Japanese people’s color-shape associations (circle-red, square-blue, triangle-yellow) can be observed by both direct and indirect experimental methods. PMID:25625717

  17. Small molecules reveal an alternative mechanism of Bax activation

    PubMed Central

    Brahmbhatt, Hetal; Uehling, David; Al-awar, Rima; Leber, Brian; Andrews, David

    2016-01-01

    The pro-apoptotic protein Bax commits a cell to death by permeabilizing the mitochondrial outer membrane (MOM). To obtain small-molecule probes for elucidating the molecular mechanism(s) of Bax activation, we screened for compounds that induced Bax-mediated liposome permeabilization. We identified five structurally different small molecules that promoted both Bax targeting to and oligomerization at membranes. All five compounds initiated Bax oligomerization in the absence of membranes by a mechanism unlike Bax activation by Bcl-2 homology 3 domain (BH3) proteins. Some of the compounds induced Bax/Bak-dependent apoptosis in cells. Activation of Bax by the most active compound was poorly inhibited by the anti-apoptotic protein Bcl-XL and requires a cysteine residue at position 126 of Bax that is not required for activation by BH3 proteins. Our results reveal a novel pathway for Bax activation independent of pro-apoptotic BH3 proteins that may have important implications for the regulation of Bax activity in cells. PMID:26916338

  18. Quantitative proteomic analysis reveals posttranslational responses to aneuploidy in yeast

    PubMed Central

    Dephoure, Noah; Hwang, Sunyoung; O'Sullivan, Ciara; Dodgson, Stacie E; Gygi, Steven P; Amon, Angelika; Torres, Eduardo M

    2014-01-01

    Aneuploidy causes severe developmental defects and is a near universal feature of tumor cells. Despite its profound effects, the cellular processes affected by aneuploidy are not well characterized. Here, we examined the consequences of aneuploidy on the proteome of aneuploid budding yeast strains. We show that although protein levels largely scale with gene copy number, subunits of multi-protein complexes are notable exceptions. Posttranslational mechanisms attenuate their expression when their encoding genes are in excess. Our proteomic analyses further revealed a novel aneuploidy-associated protein expression signature characteristic of altered metabolism and redox homeostasis. Indeed aneuploid cells harbor increased levels of reactive oxygen species (ROS). Interestingly, increased protein turnover attenuates ROS levels and this novel aneuploidy-associated signature and improves the fitness of most aneuploid strains. Our results show that aneuploidy causes alterations in metabolism and redox homeostasis. Cells respond to these alterations through both transcriptional and posttranscriptional mechanisms. DOI: http://dx.doi.org/10.7554/eLife.03023.001 PMID:25073701

  19. Metabolomics reveals insect metabolic responses associated with fungal infection.

    PubMed

    Xu, Yong-Jiang; Luo, Feifei; Gao, Qiang; Shang, Yanfang; Wang, Chengshu

    2015-06-01

    The interactions between insects and pathogenic fungi are complex. We employed metabolomic techniques to profile insect metabolic dynamics upon infection by the pathogenic fungus Beauveria bassiana. Silkworm larvae were infected with fungal spores and microscopic observations demonstrated that the exhaustion of insect hemocytes was coupled with fungal propagation in the insect body cavity. Metabolomic analyses revealed that fungal infection could significantly alter insect energy and nutrient metabolisms as well as the immune defense responses, including the upregulation of carbohydrates, amino acids, fatty acids, and lipids, but the downregulation of eicosanoids and amines. The insect antifeedant effect of the fungal infection was evident with the reduced level of maclurin (a component of mulberry leaves) in infected insects but elevated accumulations in control insects. Insecticidal and cytotoxic mycotoxins like oosporein and beauveriolides were also detected in insects at the later stages of infection. Taken together, the metabolomics data suggest that insect immune responses are energy-cost reactions and the strategies of nutrient deprivation, inhibition of host immune responses, and toxin production would be jointly employed by the fungus to kill insects. The data obtained in this study will facilitate future functional studies of genes and pathways associated with insect-fungus interactions.

  20. Whole-genome analyses reveal genetic instability of Acetobacter pasteurianus

    PubMed Central

    Azuma, Yoshinao; Hosoyama, Akira; Matsutani, Minenosuke; Furuya, Naoko; Horikawa, Hiroshi; Harada, Takeshi; Hirakawa, Hideki; Kuhara, Satoru; Matsushita, Kazunobu; Fujita, Nobuyuki; Shirai, Mutsunori

    2009-01-01

    Acetobacter species have been used for brewing traditional vinegar and are known to have genetic instability. To clarify the mutability, Acetobacter pasteurianus NBRC 3283, which forms a multi-phenotype cell complex, was subjected to genome DNA sequencing. The genome analysis revealed that there are more than 280 transposons and five genes with hyper-mutable tandem repeats as common features in the genome consisting of a 2.9-Mb chromosome and six plasmids. There were three single nucleotide mutations and five transposon insertions in 32 isolates from the cell complex. The A. pasteurianus hyper-mutability was applied for breeding a temperature-resistant strain grown at an unviable high-temperature (42°C). The genomic DNA sequence of a heritable mutant showing temperature resistance was analyzed by mutation mapping, illustrating that a 92-kb deletion and three single nucleotide mutations occurred in the genome during the adaptation. Alpha-proteobacteria including A. pasteurianus consists of many intracellular symbionts and parasites, and their genomes show increased evolution rates and intensive genome reduction. However, A. pasteurianus is assumed to be a free-living bacterium, it may have the potentiality to evolve to fit in natural niches of seasonal fruits and flowers with other organisms, such as yeasts and lactic acid bacteria. PMID:19638423

  1. Channels of oxygen diffusion in single crystal rubrene revealed.

    PubMed

    Thompson, Robert J; Bennett, Thomas; Fearn, Sarah; Kamaludin, Muhammad; Kloc, Christian; McPhail, David S; Mitrofanov, Oleg; Curson, Neil J

    2016-11-30

    Electronic devices made from organic materials have the potential to support a more ecologically friendly and affordable future. However, the ability to fabricate devices with well-defined and reproducible electrical and optical properties is hindered by the sensitivity to the presence of chemical impurities. Oxygen in particular is an impurity that can trap electrons and modify conductive properties of some organic materials. Until now the 3-dimensional profiling of oxygen species in organic semiconductors has been elusive and the effect of oxygen remains disputed. In this study we map out high-spatial resolution 3-dimensional distributions of oxygen inclusions near the surface of single crystal rubrene, using Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). Channels of diffused oxygen are found extending from uniform oxygen inclusion layers at the surface. These channels extend to depths in excess of 1.8 μm and act as an entry point for oxygen to diffuse along the ab-plane of the crystal with at least some of the diffused oxygen molecularly binding to rubrene. Our investigation of surfaces at different stages of evolution reveals the extent of oxygen inclusion, which affects rubrene's optical and transport properties, and is consequently of importance for the reliability and longevity of devices.

  2. Proteomics reveals potential biomarkers of seed vigor in sugarbeet.

    PubMed

    Catusse, Julie; Meinhard, Juliane; Job, Claudette; Strub, Jean-Marc; Fischer, Uwe; Pestsova, Elena; Westhoff, Peter; Van Dorsselaer, Alain; Job, Dominique

    2011-05-01

    To unravel biomarkers of seed vigor, an important trait conditioning crop yield, a comparative proteomic study was conducted with sugarbeet seed samples of varying vigor as generated by an invigoration treatment called hydropriming and an aging treatment called controlled deterioration. Comparative proteomics revealed proteins exhibiting contrasting behavior between seed samples. Thus, 18 proteins were up-regulated during priming and down-regulated during aging and further displayed an up-regulation upon priming of the aged seeds, meaning that down-regulation of these spot volumes during aging was reversible upon subsequent priming. Also, 11 proteins exhibited the converse behavior characterized by a decrease and an increase of the spot volumes during priming and aging of the control seeds, respectively, and a decrease in the spot volumes upon priming of the aged seeds. The results underpinned the role in seed vigor of several metabolic pathways involved in lipid and starch mobilization, protein synthesis or the methyl cycle. They also corroborate previous studies suggesting that the glyoxylate enzyme isocitrate lyase, the capacity of protein synthesis and components of abscisic acid signaling pathways are likely contributors of seed vigor.

  3. Cyp1a reporter zebrafish reveals target tissues for dioxin.

    PubMed

    Kim, Kun-Hee; Park, Hye-Jeong; Kim, Jin Hee; Kim, Suhyun; Williams, Darren R; Kim, Myeong-Kyu; Jung, Young Do; Teraoka, Hiroki; Park, Hae-Chul; Choy, Hyon E; Shin, Boo Ahn; Choi, Seok-Yong

    2013-06-15

    2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is the unintentional byproduct of various industrial processes, is classified as human carcinogen and could disrupt reproductive, developmental and endocrine systems. Induction of cyp1a1 is used as an indicator of TCDD exposure. We sought to determine tissues that are vulnerable to TCDD toxicity using a transgenic zebrafish (Danio rerio) model. We inserted a nuclear enhanced green fluorescent protein gene (EGFP) into the start codon of a zebrafish cyp1a gene in a fosmid clone using DNA recombineering. The resulting recombineered fosmid was then used to generate cyp1a reporter zebrafish, embryos of which were exposed to TCDD. Expression pattern of EGFP in the reporter zebrafish mirrored that of endogenous cyp1a mRNA. In addition, exposure of the embryos to TCDD at as low as 10 pM for 72 h, which does not elicit morphological abnormalities of embryos, markedly increased GFP expression. Furthermore, the reporter embryos responded to other AhR ligands as well. Exposure of the embryos to TCDD revealed previously reported (the cardiovascular system, liver, pancreas, kidney, swim bladder and skin) and unreported target tissues (retinal bipolar cells, otic vesicle, lateral line, cloaca and pectoral fin bud) for TCDD. Transgenic cyp1a reporter zebrafish we have developed can further understanding of ecotoxicological relevance and human health risks by TCDD. In addition, they could be used to identify agonists of AhR and antidotes to TCDD toxicity.

  4. Zircon thermometer reveals minimum melting conditions on earliest Earth.

    PubMed

    Watson, E B; Harrison, T M

    2005-05-06

    Ancient zircons from Western Australia's Jack Hills preserve a record of conditions that prevailed on Earth not long after its formation. Widely considered to have been a uniquely violent period geodynamically, the Hadean Eon [4.5 to 4.0 billion years ago (Ga)] has recently been interpreted by some as far more benign-possibly even characterized by oceans like those of the present day. Knowledge of the crystallization temperatures of the Hadean zircons is key to this debate. A thermometer based on titanium content revealed that these zircons cluster strongly at approximately 700 degrees C, which is indistinguishable from temperatures of granitoid zircon growth today and strongly suggests a regulated mechanism producing zircon-bearing rocks during the Hadean. The temperatures substantiate the existence of wet, minimum-melting conditions within 200 million years of solar system formation. They further suggest that Earth had settled into a pattern of crust formation, erosion, and sediment recycling as early as 4.35 Ga.

  5. A genome wide dosage suppressor network reveals genomic robustness

    PubMed Central

    Patra, Biranchi; Kon, Yoshiko; Yadav, Gitanjali; Sevold, Anthony W.; Frumkin, Jesse P.; Vallabhajosyula, Ravishankar R.; Hintze, Arend; Østman, Bjørn; Schossau, Jory; Bhan, Ashish; Marzolf, Bruz; Tamashiro, Jenna K.; Kaur, Amardeep; Baliga, Nitin S.; Grayhack, Elizabeth J.; Adami, Christoph; Galas, David J.; Raval, Alpan; Phizicky, Eric M.; Ray, Animesh

    2017-01-01

    Genomic robustness is the extent to which an organism has evolved to withstand the effects of deleterious mutations. We explored the extent of genomic robustness in budding yeast by genome wide dosage suppressor analysis of 53 conditional lethal mutations in cell division cycle and RNA synthesis related genes, revealing 660 suppressor interactions of which 642 are novel. This collection has several distinctive features, including high co-occurrence of mutant-suppressor pairs within protein modules, highly correlated functions between the pairs and higher diversity of functions among the co-suppressors than previously observed. Dosage suppression of essential genes encoding RNA polymerase subunits and chromosome cohesion complex suggests a surprising degree of functional plasticity of macromolecular complexes, and the existence of numerous degenerate pathways for circumventing the effects of potentially lethal mutations. These results imply that organisms and cancer are likely able to exploit the genomic robustness properties, due the persistence of cryptic gene and pathway functions, to generate variation and adapt to selective pressures. PMID:27899637

  6. Single-Cell RNA-Seq Reveals Hypothalamic Cell Diversity.

    PubMed

    Chen, Renchao; Wu, Xiaoji; Jiang, Lan; Zhang, Yi

    2017-03-28

    The hypothalamus is one of the most complex brain structures involved in homeostatic regulation. Defining cell composition and identifying cell-type-specific transcriptional features of the hypothalamus is essential for understanding its functions and related disorders. Here, we report single-cell RNA sequencing results of adult mouse hypothalamus, which defines 11 non-neuronal and 34 neuronal cell clusters with distinct transcriptional signatures. Analyses of cell-type-specific transcriptomes reveal gene expression dynamics underlying oligodendrocyte differentiation and tanycyte subtypes. Additionally, data analysis provides a comprehensive view of neuropeptide expression across hypothalamic neuronal subtypes and uncover Crabp1(+) and Pax6(+) neuronal populations in specific hypothalamic sub-regions. Furthermore, we found food deprivation exhibited differential transcriptional effects among the different neuronal subtypes, suggesting functional specification of various neuronal subtypes. Thus, the work provides a comprehensive transcriptional perspective of adult hypothalamus, which serves as a valuable resource for dissecting cell-type-specific functions of this complex brain region.

  7. Revealing hidden regularities with a general approach to fission

    NASA Astrophysics Data System (ADS)

    Schmidt, Karl-Heinz; Jurado, Beatriz

    2015-12-01

    Selected aspects of a general approach to nuclear fission are described with the focus on the possible benefit of meeting the increasing need of nuclear data for the existing and future emerging nuclear applications. The most prominent features of this approach are the evolution of quantum-mechanical wave functions in systems with complex shape, memory effects in the dynamics of stochastic processes, the influence of the Second Law of thermodynamics on the evolution of open systems in terms of statistical mechanics, and the topological properties of a continuous function in multi-dimensional space. It is demonstrated that this approach allows reproducing the measured fission barriers and the observed properties of the fission fragments and prompt neutrons. Our approach is based on sound physical concepts, as demonstrated by the fact that practically all the parameters have a physical meaning, and reveals a high degree of regularity in the fission observables. Therefore, we expect a good predictive power within the region extending from Po isotopes to Sg isotopes where the model parameters have been adjusted. Our approach can be extended to other regions provided that there is enough empirical information available that allows determining appropriate values of the model parameters. Possibilities for combining this general approach with microscopic models are suggested. These are supposed to enhance the predictive power of the general approach and to help improving or adjusting the microscopic models. This could be a way to overcome the present difficulties for producing evaluations with the required accuracy.

  8. Crystallographic and spectroscopic snapshots reveal a dehydrogenase in action

    PubMed Central

    Huo, Lu; Davis, Ian; Liu, Fange; Andi, Babak; Esaki, Shingo; Iwaki, Hiroaki; Hasegawa, Yoshie; Orville, Allen M.; Liu, Aimin

    2015-01-01

    Aldehydes are ubiquitous intermediates in metabolic pathways and their innate reactivity can often make them quite unstable. There are several aldehydic intermediates in the metabolic pathway for tryptophan degradation that can decay into neuroactive compounds that have been associated with numerous neurological diseases. An enzyme of this pathway, 2-aminomuconate-6-semialdehyde dehydrogenase, is responsible for ‘disarming’ the final aldehydic intermediate. Here we show the crystal structures of a bacterial analogue enzyme in five catalytically relevant forms: resting state, one binary and two ternary complexes, and a covalent, thioacyl intermediate. We also report the crystal structures of a tetrahedral, thiohemiacetal intermediate, a thioacyl intermediate and an NAD+-bound complex from an active site mutant. These covalent intermediates are characterized by single-crystal and solution-state electronic absorption spectroscopy. The crystal structures reveal that the substrate undergoes an E/Z isomerization at the enzyme active site before an sp3-to-sp2 transition during enzyme-mediated oxidation. PMID:25565451

  9. Super-resolution Microscopy Reveals Compartmentalization of Peroxisomal Membrane Proteins*

    PubMed Central

    Galiani, Silvia; Waithe, Dominic; Reglinski, Katharina; Cruz-Zaragoza, Luis Daniel; Garcia, Esther; Clausen, Mathias P.; Schliebs, Wolfgang; Erdmann, Ralf; Eggeling, Christian

    2016-01-01

    Membrane-associated events during peroxisomal protein import processes play an essential role in peroxisome functionality. Many details of these processes are not known due to missing spatial resolution of technologies capable of investigating peroxisomes directly in the cell. Here, we present the use of super-resolution optical stimulated emission depletion microscopy to investigate with sub-60-nm resolution the heterogeneous spatial organization of the peroxisomal proteins PEX5, PEX14, and PEX11 around actively importing peroxisomes, showing distinct differences between these peroxins. Moreover, imported protein sterol carrier protein 2 (SCP2) occupies only a subregion of larger peroxisomes, highlighting the heterogeneous distribution of proteins even within the peroxisome. Finally, our data reveal subpopulations of peroxisomes showing only weak colocalization between PEX14 and PEX5 or PEX11 but at the same time a clear compartmentalized organization. This compartmentalization, which was less evident in cases of strong colocalization, indicates dynamic protein reorganization linked to changes occurring in the peroxisomes. Through the use of multicolor stimulated emission depletion microscopy, we have been able to characterize peroxisomes and their constituents to a yet unseen level of detail while maintaining a highly statistical approach, paving the way for equally complex biological studies in the future. PMID:27311714

  10. Archaeopteryx feathers and bone chemistry fully revealed via synchrotron imaging

    PubMed Central

    Bergmann, U.; Morton, R. W.; Manning, P. L.; Sellers, W. I.; Farrar, S.; Huntley, K. G.; Wogelius, R. A.; Larson, P.

    2010-01-01

    Evolution of flight in maniraptoran dinosaurs is marked by the acquisition of distinct avian characters, such as feathers, as seen in Archaeopteryx from the Solnhofen limestone. These rare fossils were pivotal in confirming the dinosauria-avian lineage. One of the key derived avian characters is the possession of feathers, details of which were remarkably preserved in the Lagerstätte environment. These structures were previously simply assumed to be impressions; however, a detailed chemical analysis has, until now, never been completed on any Archaeopteryx specimen. Here we present chemical imaging via synchrotron rapid scanning X-ray fluorescence (SRS-XRF) of the Thermopolis Archaeopteryx, which shows that portions of the feathers are not impressions but are in fact remnant body fossil structures, maintaining elemental compositions that are completely different from the embedding geological matrix. Our results indicate phosphorous and sulfur retention in soft tissue as well as trace metal (Zn and Cu) retention in bone. Other previously unknown chemical details of Archaeopteryx are also revealed in this study including: bone chemistry, taphonomy (fossilization process), and curation artifacts. SRS-XRF represents a major advancement in the study of the life chemistry and fossilization processes of Archaeopteryx and other extinct organisms because it is now practical to image the chemistry of large specimens rapidly at concentration levels of parts per million. This technique has wider application to the archaeological, forensic, and biological sciences, enabling the mapping of “unseen” compounds critical to understanding biological structures, modes of preservation, and environmental context. PMID:20457935

  11. Archaeopteryx feathers and bone chemistry fully revealed via synchrotron imaging.

    PubMed

    Bergmann, U; Morton, R W; Manning, P L; Sellers, W I; Farrar, S; Huntley, K G; Wogelius, R A; Larson, P

    2010-05-18

    Evolution of flight in maniraptoran dinosaurs is marked by the acquisition of distinct avian characters, such as feathers, as seen in Archaeopteryx from the Solnhofen limestone. These rare fossils were pivotal in confirming the dinosauria-avian lineage. One of the key derived avian characters is the possession of feathers, details of which were remarkably preserved in the Lagerstätte environment. These structures were previously simply assumed to be impressions; however, a detailed chemical analysis has, until now, never been completed on any Archaeopteryx specimen. Here we present chemical imaging via synchrotron rapid scanning X-ray fluorescence (SRS-XRF) of the Thermopolis Archaeopteryx, which shows that portions of the feathers are not impressions but are in fact remnant body fossil structures, maintaining elemental compositions that are completely different from the embedding geological matrix. Our results indicate phosphorous and sulfur retention in soft tissue as well as trace metal (Zn and Cu) retention in bone. Other previously unknown chemical details of Archaeopteryx are also revealed in this study including: bone chemistry, taphonomy (fossilization process), and curation artifacts. SRS-XRF represents a major advancement in the study of the life chemistry and fossilization processes of Archaeopteryx and other extinct organisms because it is now practical to image the chemistry of large specimens rapidly at concentration levels of parts per million. This technique has wider application to the archaeological, forensic, and biological sciences, enabling the mapping of "unseen" compounds critical to understanding biological structures, modes of preservation, and environmental context.

  12. Automatic decoding of facial movements reveals deceptive pain expressions.

    PubMed

    Bartlett, Marian Stewart; Littlewort, Gwen C; Frank, Mark G; Lee, Kang

    2014-03-31

    In highly social species such as humans, faces have evolved to convey rich information for social interaction, including expressions of emotions and pain [1-3]. Two motor pathways control facial movement [4-7]: a subcortical extrapyramidal motor system drives spontaneous facial expressions of felt emotions, and a cortical pyramidal motor system controls voluntary facial expressions. The pyramidal system enables humans to simulate facial expressions of emotions not actually experienced. Their simulation is so successful that they can deceive most observers [8-11]. However, machine vision may be able to distinguish deceptive facial signals from genuine facial signals by identifying the subtle differences between pyramidally and extrapyramidally driven movements. Here, we show that human observers could not discriminate real expressions of pain from faked expressions of pain better than chance, and after training human observers, we improved accuracy to a modest 55%. However, a computer vision system that automatically measures facial movements and performs pattern recognition on those movements attained 85% accuracy. The machine system's superiority is attributable to its ability to differentiate the dynamics of genuine expressions from faked expressions. Thus, by revealing the dynamics of facial action through machine vision systems, our approach has the potential to elucidate behavioral fingerprints of neural control systems involved in emotional signaling.

  13. Genomic analysis of primordial dwarfism reveals novel disease genes.

    PubMed

    Shaheen, Ranad; Faqeih, Eissa; Ansari, Shinu; Abdel-Salam, Ghada; Al-Hassnan, Zuhair N; Al-Shidi, Tarfa; Alomar, Rana; Sogaty, Sameera; Alkuraya, Fowzan S

    2014-02-01

    Primordial dwarfism (PD) is a disease in which severely impaired fetal growth persists throughout postnatal development and results in stunted adult size. The condition is highly heterogeneous clinically, but the use of certain phenotypic aspects such as head circumference and facial appearance has proven helpful in defining clinical subgroups. In this study, we present the results of clinical and genomic characterization of 16 new patients in whom a broad definition of PD was used (e.g., 3M syndrome was included). We report a novel PD syndrome with distinct facies in two unrelated patients, each with a different homozygous truncating mutation in CRIPT. Our analysis also reveals, in addition to mutations in known PD disease genes, the first instance of biallelic truncating BRCA2 mutation causing PD with normal bone marrow analysis. In addition, we have identified a novel locus for Seckel syndrome based on a consanguineous multiplex family and identified a homozygous truncating mutation in DNA2 as the likely cause. An additional novel PD disease candidate gene XRCC4 was identified by autozygome/exome analysis, and the knockout mouse phenotype is highly compatible with PD. Thus, we add a number of novel genes to the growing list of PD-linked genes, including one which we show to be linked to a novel PD syndrome with a distinct facial appearance. PD is extremely heterogeneous genetically and clinically, and genomic tools are often required to reach a molecular diagnosis.

  14. Integrative network analysis reveals molecular mechanisms of blood pressure regulation

    PubMed Central

    Huan, Tianxiao; Meng, Qingying; Saleh, Mohamed A; Norlander, Allison E; Joehanes, Roby; Zhu, Jun; Chen, Brian H; Zhang, Bin; Johnson, Andrew D; Ying, Saixia; Courchesne, Paul; Raghavachari, Nalini; Wang, Richard; Liu, Poching; O'Donnell, Christopher J; Vasan, Ramachandran; Munson, Peter J; Madhur, Meena S; Harrison, David G; Yang, Xia; Levy, Daniel

    2015-01-01

    Genome-wide association studies (GWAS) have identified numerous loci associated with blood pressure (BP). The molecular mechanisms underlying BP regulation, however, remain unclear. We investigated BP-associated molecular mechanisms by integrating BP GWAS with whole blood mRNA expression profiles in 3,679 individuals, using network approaches. BP transcriptomic signatures at the single-gene and the coexpression network module levels were identified. Four coexpression modules were identified as potentially causal based on genetic inference because expression-related SNPs for their corresponding genes demonstrated enrichment for BP GWAS signals. Genes from the four modules were further projected onto predefined molecular interaction networks, revealing key drivers. Gene subnetworks entailing molecular interactions between key drivers and BP-related genes were uncovered. As proof-of-concept, we validated SH2B3, one of the top key drivers, using Sh2b3−/− mice. We found that a significant number of genes predicted to be regulated by SH2B3 in gene networks are perturbed in Sh2b3−/− mice, which demonstrate an exaggerated pressor response to angiotensin II infusion. Our findings may help to identify novel targets for the prevention or treatment of hypertension. PMID:25882670

  15. Phylogenies reveal predictive power of traditional medicine in bioprospecting.

    PubMed

    Saslis-Lagoudakis, C Haris; Savolainen, Vincent; Williamson, Elizabeth M; Forest, Félix; Wagstaff, Steven J; Baral, Sushim R; Watson, Mark F; Pendry, Colin A; Hawkins, Julie A

    2012-09-25

    There is controversy about whether traditional medicine can guide drug discovery, and investment in bioprospecting informed by ethnobotanical data has fluctuated. One view is that traditionally used medicinal plants are not necessarily efficacious and there are no robust methods for distinguishing those which are most likely to be bioactive when selecting species for further testing. Here, we reconstruct a genus-level molecular phylogenetic tree representing the 20,000 species found in the floras of three disparate biodiversity hotspots: Nepal, New Zealand, and the Cape of South Africa. Borrowing phylogenetic methods from community ecology, we reveal significant clustering of the 1,500 traditionally used species, and provide a direct measure of the relatedness of the three medicinal floras. We demonstrate shared phylogenetic patterns across the floras: related plants from these regions are used to treat medical conditions in the same therapeutic areas. This finding strongly indicates independent discovery of plant efficacy, an interpretation corroborated by the presence of a significantly greater proportion of known bioactive species in these plant groups than in random samples. We conclude that phylogenetic cross-cultural comparisons can focus screening efforts on a subset of traditionally used plants that are richer in bioactive compounds, and could revitalize the use of traditional knowledge in bioprospecting.

  16. Strategy Revealing Phenotypic Differences among Synthetic Oscillator Designs

    PubMed Central

    2015-01-01

    Considerable progress has been made in identifying and characterizing the component parts of genetic oscillators, which play central roles in all organisms. Nonlinear interaction among components is sufficiently complex that mathematical models are required to elucidate their elusive integrated behavior. Although natural and synthetic oscillators exhibit common architectures, there are numerous differences that are poorly understood. Utilizing synthetic biology to uncover basic principles of simpler circuits is a way to advance understanding of natural circadian clocks and rhythms. Following this strategy, we address the following questions: What are the implications of different architectures and molecular modes of transcriptional control for the phenotypic repertoire of genetic oscillators? Are there designs that are more realizable or robust? We compare synthetic oscillators involving one of three architectures and various combinations of the two modes of transcriptional control using a methodology that provides three innovations: a rigorous definition of phenotype, a procedure for deconstructing complex systems into qualitatively distinct phenotypes, and a graphical representation for illuminating the relationship between genotype, environment, and the qualitatively distinct phenotypes of a system. These methods provide a global perspective on the behavioral repertoire, facilitate comparisons of alternatives, and assist the rational design of synthetic gene circuitry. In particular, the results of their application here reveal distinctive phenotypes for several designs that have been studied experimentally as well as a best design among the alternatives that has yet to be constructed and tested. PMID:25019938

  17. Geometric Mechanics Reveals Optimal Complex Terrestrial Undulation Patterns

    NASA Astrophysics Data System (ADS)

    Gong, Chaohui; Astley, Henry; Schiebel, Perrin; Dai, Jin; Travers, Matthew; Goldman, Daniel; Choset, Howie; CMU Team; GT Team

    Geometric mechanics offers useful tools for intuitively analyzing biological and robotic locomotion. However, utility of these tools were previously restricted to systems that have only two internal degrees of freedom and in uniform media. We show kinematics of complex locomotors that make intermittent contacts with substrates can be approximated as a linear combination of two shape bases, and can be represented using two variables. Therefore, the tools of geometric mechanics can be used to analyze motions of locomotors with many degrees of freedom. To demonstrate the proposed technique, we present studies on two different types of snake gaits which utilize combinations of waves in the horizontal and vertical planes: sidewinding (in the sidewinder rattlesnake C. cerastes) and lateral undulation (in the desert specialist snake C. occipitalis). C. cerastes moves by generating posteriorly traveling body waves in the horizontal and vertical directions, with a relative phase offset equal to +/-π/2 while C. occipitalismaintains a π/2 offset of a frequency doubled vertical wave. Geometric analysis reveals these coordination patterns enable optimal movement in the two different styles of undulatory terrestrial locomotion. More broadly, these examples demonstrate the utility of geometric mechanics in analyzing realistic biological and robotic locomotion.

  18. Beyond Contagion: Reality Mining Reveals Complex Patterns of Social Influence.

    PubMed

    Alshamsi, Aamena; Pianesi, Fabio; Lepri, Bruno; Pentland, Alex; Rahwan, Iyad

    2015-01-01

    Contagion, a concept from epidemiology, has long been used to characterize social influence on people's behavior and affective (emotional) states. While it has revealed many useful insights, it is not clear whether the contagion metaphor is sufficient to fully characterize the complex dynamics of psychological states in a social context. Using wearable sensors that capture daily face-to-face interaction, combined with three daily experience sampling surveys, we collected the most comprehensive data set of personality and emotion dynamics of an entire community of work. From this high-resolution data about actual (rather than self-reported) face-to-face interaction, a complex picture emerges where contagion (that can be seen as adaptation of behavioral responses to the behavior of other people) cannot fully capture the dynamics of transitory states. We found that social influence has two opposing effects on states: adaptation effects that go beyond mere contagion, and complementarity effects whereby individuals' behaviors tend to complement the behaviors of others. Surprisingly, these effects can exhibit completely different directions depending on the stable personality or emotional dispositions (stable traits) of target individuals. Our findings provide a foundation for richer models of social dynamics, and have implications on organizational engineering and workplace well-being.

  19. Experimental evolution reveals hidden diversity in evolutionary pathways

    PubMed Central

    Lind, Peter A; Farr, Andrew D; Rainey, Paul B

    2015-01-01

    Replicate populations of natural and experimental organisms often show evidence of parallel genetic evolution, but the causes are unclear. The wrinkly spreader morph of Pseudomonas fluorescens arises repeatedly during experimental evolution. The mutational causes reside exclusively within three pathways. By eliminating these, 13 new mutational pathways were discovered with the newly arising WS types having fitnesses similar to those arising from the commonly passaged routes. Our findings show that parallel genetic evolution is strongly biased by constraints and we reveal the genetic bases. From such knowledge, and in instances where new phenotypes arise via gene activation, we suggest a set of principles: evolution proceeds firstly via pathways subject to negative regulation, then via promoter mutations and gene fusions, and finally via activation by intragenic gain-of-function mutations. These principles inform evolutionary forecasting and have relevance to interpreting the diverse array of mutations associated with clinically identical instances of disease in humans. DOI: http://dx.doi.org/10.7554/eLife.07074.001 PMID:25806684

  20. Enzyme kinetics: the whole picture reveals hidden meanings.

    PubMed

    Pinto, Maria F; Estevinho, Berta N; Crespo, Rosa; Rocha, Fernando A; Damas, Ana M; Martins, Pedro M

    2015-06-01

    The methodology adopted by Michaelis and Menten in 1913 is still routinely used to characterize the catalytic power and selectivity of enzymes. These kinetic measurements must be performed soon after the purified enzyme is mixed with a large excess of substrate. Other time scales and solution compositions are no less physiologically relevant, but fall outside the range of applicability of the classical formalism. Here we show that the complete picture of an enzyme's mode of function is critically obscured by the limited scope of conventional kinetic analysis, even in the simplest case of a single active site without inhibition. This picture is now unveiled in a mathematically closed form that remains valid over the reaction time for all combinations of enzyme/substrate concentrations and rate constants. Algebraic simplicity is maintained in the new formalism when stationary reaction phases are considered. By achieving this century-old objective, the otherwise hidden role of the reversible binding step is revealed and atypical kinetic profiles are explained. Most singular kinetic behaviors are identified in a critical region of conditions that coincide with typical cell conditions. Because it is not covered by the Michaelis-Menten model, the critical region has been missed until now by low- and high-throughput screenings of new drugs. New possibilities are therefore raised for novel and once-promising inhibitors to therapeutically target enzymes.