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Sample records for smectic-c mesophases revealed

  1. Structures of chiral smectic-C mesophases revealed by polarization-analyzed resonant x-ray scattering

    SciTech Connect

    Mach, P.; Pindak, R.; Levelut, A.-M.; Barois, P.; Nguyen, H. T.; Baltes, H.; Hird, M.; Toyne, K.; Seed, A.; Goodby, J. W.

    1999-12-01

    We report polarization-analyzed, resonant x-ray diffraction at the sulfur K edge performed upon free-standing liquid-crystal films. Our studies of the thiobenzoate liquid-crystal enantiomer 10OTBBB1M7 yield the polarization states of resonant satellite peaks arising from characteristic superlattices in the chiral smectic-C (SmC{sup *}) variant phases, including the antiferroelectric SmC{sub A}{sup *}, ferrielectric SmC{sub FI1}{sup *} and SmC{sub FI2}{sup *}, as well as SmC{sub {alpha}}{sup *}. The observed polarizations agree with the clock model of chiral smectic-C variants, and rule out other proposals made to date for these structures. Data from the 10OTBBB1M7 racemate also support the clock model. Our resonant diffraction results from a thiophene liquid-crystal compound reveal the same superlattice periodicities seen in corresponding antiferroelectric and ferrielectric phases of 10OTBBB1M7. (c) 1999 The American Physical Society.

  2. 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.

  3. Generation of frustrated liquid crystal phases by mixing an achiral nematic-smectic-C mesogen with an antiferroelectric chiral smectic liquid crystal.

    PubMed

    Lagerwall, Jan P F; Giesselmann, Frank; Selbmann, Christine; Rauch, Sebastian; Heppke, Gerd

    2005-04-01

    By mixing the achiral liquid crystal HOAB, exhibiting a nematic (N)-smectic-C (SmC) mesophase sequence, with the chiral antiferroelectric liquid crystal (AFLC) (S,S)-M7BBM7, forming the antiferroelectric SmC(a)(*) phase, at least seven different mesophases have been induced which neither component forms on its own: a twist-grain-boundary (TGB(*)) phase, two or three blue phases, the untilted SmA(*) phase, as well as all three chiral smectic-C-type "subphases," SmC(alpha)(*), SmC(beta)(*), and SmC(gamma)(*). The nature of the induced phases and the transitions between them were determined by means of optical and electro-optical investigations, dielectric spectroscopy, and differential scanning calorimetry. The induced phases can to a large extent be understood as a result of frustration, TGB(*) at the border between nematic and smectic, the subphases between syn and anticlinic tilted smectic organization. X ray scattering experiments reveal that the smectic layer spacing as well as the degree of smectic order is relatively constant in the whole mixture composition range in which AFLC behavior prevails, whereas both these parameters rapidly decrease as the amount of HOAB is increased to such an extent that no other smectic-C-type phase than SmC/SmC(*) exists. By tailoring the composition we are able to produce liquid crystal mixtures exhibiting unusual phase sequences, e.g., with a direct isotropic-SmC(a)(*) transition or a temperature range of the SmC(beta)(*) subphase of about 50 K.

  4. Effects of doping on an unusual smectic- C*alpha-smectic-C*FI2-smectic-C* phase sequence.

    PubMed

    McCoy, B K; Liu, Z Q; Wang, S T; Pan, Lidong; Wang, Shun; Nguyen, H T; Pindak, R; Huang, C C

    2008-06-01

    The compound 10OHF has a partially inverted phase sequence, unique among the series of nOHF homologous compounds and all other known liquid crystals, with the smectic-C*FI2 (SmC*FI2) phase occurring at higher temperature than the smectic-C* (SmC*) phase. We present ellipsometric data to identify the phase sequences of 9OHF, 10OHF, 11OHF, and 12OHF. Binary mixtures of 10OHF with C11, a compound with the typical phase sequence among the smectic phases, show that the unusual phase sequence of 10OHF stabilizes upon mixing and that SmC*FI2 predominates over SmC* throughout the entire mixing phase diagram. In thin films of some mixtures, surface interactions induce a reentrant SmC*FI2-SmC*-SmC*FI2 transition in the rest of the film.

  5. 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.

  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

    2015-10-01

    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. Unique pitch evolution in the smectic-C+alpha phase.

    PubMed

    Liu, Z Q; McCoy, B K; Wang, S T; Pindak, R; Caliebe, W; Barois, P; Fernandes, P; Nguyen, H T; Hsu, C S; Wang, Shun; Huang, C C

    2007-08-17

    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*(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.

  8. 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.

  9. Smectic-A and smectic-C phases and phase transitions in 8¯S5 liquid-crystal-aerosil gels

    NASA Astrophysics Data System (ADS)

    Freelon, B.; Ramazanoglu, M.; Chung, P. J.; Page, R. N.; Lo, Yuan-Tse; Valdivia, P.; Garland, C. W.; Birgeneau, R. J.

    2011-09-01

    High-resolution x-ray scattering studies of the nonpolar thermotropic liquid crystal 4-n-pentylphenylthiol-4'-n-octyloxybenzoate (8¯S5) in aerosil gel nanonetworks reveal that the aerosil-induced disorder significantly alters both the nematic to smectic-A and smectic-A to smectic-C phase transitions. The limiting 8¯S5 smectic-A correlation length follows a power-law dependence on the aerosil density in quantitative agreement with the limiting lengths measured previously in other smectic-A liquid crystal gels. The smectic-A to smectic-C liquid crystalline phase transition is altered fundamentally by the presence of the aerosil gel. The onset of the smectic-C phase remains relatively sharp but there is an extended coexistence region where smectic-A and smectic-C domains can exist.

  10. Molecular model for the anticlinic smectic-C(A) phase

    PubMed

    Osipov; Fukuda

    2000-09-01

    Both phenomenological and molecular-statistical theories of the anticlinic smectic-C(A) phase (Sm-C(A)) are considered in detail. The anticlinic structure produces antiferroelectricity in the chiral smectic-C(A) phase (Sm-C(A)*). The molecular theory is based on a simple model potential which stabilizes Sm-C(A) with respect to the synclinic smectic-C phase (Sm-C). Conventional dispersion and steric interactions between mesogenic molecules generally do not promote Sm-C(A). It may be stabilized by interlayer orientational correlations between transverse molecular dipoles located in the flexible chains. Such correlations are not sensitive to molecular handedness (chirality), and thus the theory accounts for the formation of the anticlinic phase in racemic mixtures. The model is also confirmed by other experimental data. Finally a simple phase diagram of the perfectly ordered smectic liquid crystal is presented which contains Sm-A, Sm-C, and Sm-C(A).

  11. Anisotropy of electrostatic interaction in smectic-C^{*} liquid crystals.

    PubMed

    Romanov, V P; Ulyanov, S V

    2014-11-01

    The contribution to the free energy of distortion of the ferroelectric smectic-C^{*} due to the electrostatic interaction of polarization charges is calculated. These calculations are performed by accounting for the anisotropy of the permittivity, which is essential for smectic-C^{*}. Fluctuations of the c director in an external electric field are considered. It is shown that the anisotropy of the permittivity strongly affects the interaction of the polarization charges, the spectrum orientation fluctuations, and the angular dependence of the light scattering intensity.

  12. High-resolution calorimetric study of phase transitions in chiral smectic-C liquid crystalline phases.

    PubMed

    Sasaki, Y; Le, K V; Aya, S; Isobe, M; Yao, H; Huang, C C; Takezoe, H; Ema, K

    2012-12-01

    We carried out an improved characterization of phase transitions among chiral smectic-C subphases observed for various antiferroelectric liquid crystals by precise heat capacity measurements. It was found that the phase transitions are intrinsically first order exhibiting a remarkable heat anomaly which involves little pretransitional thermal fluctuation and a finite thermal hysteresis. On the other hand, we also noticed that the critical point of the smectic-C(α)(*)-smectic-C* transition is induced by the destabilization of the smectic-C(α)(*) phase which couples with the fluctuation associated with the smectic-A-smectic-C(α)(*) phase transition.

  13. Ring-pattern dynamics in smectic-C* and smectic-C*A freely suspended liquid crystal films.

    PubMed

    Link, D R; Radzihovsky, L; Natale, G; Maclennan, J E; Clark, N A; Walsh, M; Keast, S S; Neubert, M E

    2000-06-19

    Ring patterns of concentric 2pi solitons in molecular orientation form in freely suspended chiral smectic-C films in response to an in-plane rotating electric field. We present measurements of the driven dynamics of ring formation under conditions of synchronous winding and of the zero-field relaxation of ring patterns, and propose a simple model which enables their quantitative description in low polarization DOBAMBC. In smectic-C*A TFMHPOBC we observe an odd-even layer number effect, with odd layer number films exhibiting order of magnitude slower relaxation rates than even layer films. We show that this rate difference is due to a much larger spontaneous polarization in odd layer number films. PMID:10991051

  14. Nature of a nematic--smectic-A--smectic-C multicritical point

    SciTech Connect

    Huang, C.C.; Lien, S.C.

    1981-12-28

    Recent x-ray data on the angles and 2-theta shifts in the smectic-C phase of a binary liquid-crystal mixture were analyzed via a mean-field theory. We demonstrated that the smectic-A--smectic-C transitions (AC) are mean-field--like. This conclusion is consistent with recent heat-capacity data along the AC transition line. Furthermore, the nematic--smectic-A--smectic-C point in this binary mixture system is found to be in the vicinity of the tricritical point along the AC and nematic--smectic-C transition line.

  15. Travelling waves in two-dimensional smectic-C domains.

    PubMed

    Claret, J; Crusats, J; Albalat, R; Ignés-Mullol, J; Martínez-Seara, H; Reigada, R; Sagués, F

    2006-10-01

    Continued irradiation of smectic-C-like domains of photosensitive Langmuir monolayers from azobenzene derivatives induces the nucleation and propagation of orientational travelling waves as observed with Brewster angle microscopy (BAM). BAM image analysis has allowed to identify different dynamical behaviors involving the generation and propagation of such waves. A model based on the coupling between an orientational and a composition field proposes a scenario for dynamic self-assembly that accounts for most of the observed phenomena, and allows to pinpoint the relevance of boundary defects in wave-emitting structures.-1.

  16. Systematic variation of length ratio and the formation of smectic A and smectic C phases.

    PubMed

    Kapernaum, Nadia; Hartley, C Scott; Roberts, Jeffrey C; Schoerg, Florian; Krueerke, Daniel; Lemieux, Robert P; Giesselmann, Frank

    2010-07-12

    The phase diagrams of four binary mixtures of chemically similar smectogenic mesogens differing only in molecular length are investigated. In these bidisperse systems the length ratio varies systematically. The phase diagrams show the stabilization of the smectic A and the destabilization of the smectic C phase with increasing length ratio as a general trend. Detailed small-angle X-ray diffraction and electro-optic measurements revealed a decrease in smectic translational order and a continuous reduction of the tilt angle with increasing length difference. These surprising results are of general interest for the understanding of the structure and dynamics of smectic phases. The remarkably strong impact of the length difference on the smectic layer structure and the phase behavior is discussed from a mechanistic point of view taking into account sterical interactions. For the observed structural changes in these bidisperse smectics we propose pronounced out-of-layer fluctuations with increasing length difference as driving force, causing neighboring molecules within nearest layer into a smectic A-like packing.

  17. Observation of a pretransitional effect near a virtual smectic-A{endash}smectic-C{sup *} transition

    SciTech Connect

    Shibahara, Seiji; Takanishi, Yoichi; Yamamoto, Jun; Ogasawara, Toyokazu; Ishikawa, Ken; Yokoyama, Hiroshi; Takezoe, Hideo

    2001-06-01

    Unusual softening of the layer compression modulus B has been observed near the phase boundary where the smectic-C{sup *} phase vanishes in a naphtalene-based liquid crystal mixture. From the systematic study of x-ray and layer compression measurements, this unusual effect is attributed to the pretransitional softening near a virtual smectic-A{endash}smectic-C{sup *} phase transition in the smectic-A phase, which no longer appears on the thermoequilibrium phase diagram. This phenomenon is similar but not equivalent to supercritical behavior.

  18. Amphiphilic Liquid Crystal Exhibiting the Smectic A to Smectic C Phase Transition without Layer Contraction

    NASA Astrophysics Data System (ADS)

    Ishida, Norihiro; Takanishi, Yoichi; Yamamoto, Jun; Yoshizawa, Atsushi

    2011-02-01

    We prepared an amphiphilic liquid crystal composed of a semiperfluorinated alkyl chain and a 2,3-difluoro-1,4-diphenylbenzene core, and investigated its physical properties using polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. The compound was found to exhibit the smectic A to smectic C phase transition without layer contraction. The compound doped with a ferroelectric liquid crystal exhibited a fast electro-optical switching with a response time of 10 µs in the chiral smectic A phase in spite of the absence of a chiral smectic C phase. The phase transition behavior is interpreted using the de Vries cone model.

  19. Observation of a pretransitional effect near a virtual smectic-A--smectic-C* transition.

    PubMed

    Shibahara, S; Takanishi, Y; Yamamoto, J; Ogasawara, T; Ishikawa, K; Yokoyama, H; Takezoe, H

    2001-06-01

    Unusual softening of the layer compression modulus B has been observed near the phase boundary where the smectic-C* phase vanishes in a naphtalene-based liquid crystal mixture. From the systematic study of x-ray and layer compression measurements, this unusual effect is attributed to the pretransitional softening near a virtual smectic-A-smectic-C* phase transition in the smectic-A phase, which no longer appears on the thermoequilibrium phase diagram. This phenomenon is similar but not equivalent to supercritical behavior.

  20. Molecular theory of ferroelectric ordering in enantiomeric mixtures of smectic-C* liquid crystals.

    PubMed

    Osipov, M A; Guillon, D

    1999-12-01

    A molecular theory of ferroelectric ordering in smectic-C* liquid crystals composed of left and right enantiomers is developed taking into account the effects of chiral discrimination. The recently observed nonlinear dependence of the spontaneous polarization on the enantiomeric excess is explained in the framework of a molecular model that takes into consideration the strong electrostatic interaction between effective atomic charges in the chiral centers of the two enantiomers. This nonlinear dependence is determined by a difference of interaction energies between the pairs of chiral molecules with equal and opposite handedness, respectively. A relation between the molecular structure of different ferroelectric smectics C* and the dependence of the polarization on the enantiomeric excess is discussed in detail.

  1. Reorientation dynamics of ferroelectric liquid-crystal molecules near the smectic-A-smectic-C* transition

    NASA Astrophysics Data System (ADS)

    O'brien, J. P.; Moses, T.; Chen, W.; Freysz, E.; Ouchi, Y.; Shen, Y. R.

    1993-04-01

    A transient optical Kerr measurement is used to study molecular reorientation about the long molecular axis of chiral and nonchiral smectic-A liquid crystals. Two relaxation components were identified, associated with individual and collective molecular motions. In contradiction with a recent report [J. R. Lalanne et al., Phys. Rev. Lett. 62, 3046 (1989); Phys. Rev. A 44, 6632 (1991)], no critical behavior of this reorientation was observed as the transition to the ferroelectric smectic-C* phase was approached.

  2. Design, synthesis and characterization of a linear hydrogen bonded homologous series exhibiting reentrant smectic C ordering

    NASA Astrophysics Data System (ADS)

    Kavitha, C.; Madhu Mohan, M. L. N.

    2012-10-01

    Design, synthesis and characterization of seven linear hydrogen bonded liquid crystal complexes derived from mesogenic p-n-decyloxy benzoic acid and p-n-alkyl benzoic acids designated as 10OØn (where n varied from ethyl to octyl) are reported. FTIR studies confirm the hydrogen bond formation in all these complexes. The phase transition temperatures and their corresponding enthalpy values are experimentally deduced from Differential Scanning Calorimetry (DSC) studies. POM and DSC data are further utilized for the construction of 10OØn phase diagram. Two Odd-even effects have been evinced, one in enthalpy values and the other in corresponding transition temperatures across the isotropic to nematic phase transition. An interesting result is the observation of re-entrant smectic ordering, designated as smectic CR in three higher ordered mesogens. A new smectic ordering, smectic X, has been observed which is sandwiched between traditional smectic C and re-entrant smectic CR. Magnitudes of optical tilt angle in smectic C, smectic X and smectic CR are experimentally found to attain saturation with decrement of temperature in the corresponding phase. The occurrence of smectic X and smectic CR are discussed with relation to the molecular chemical structure. The optical filtering action in smectic C and re-entrant smectic CR phases have been analyzed.

  3. 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.

  4. Solubilization of gabapentin into HII mesophases.

    PubMed

    Achrai, Ben; Libster, Dima; Aserin, Abraham; Garti, Nissim

    2011-02-10

    In the present work, we report on the solubilization of gabapentin (GBP) into lyotropic hexagonal mesophases composed of monoolein, tricaprylin, and water. It was demonstrated that the hexagonal structure remained intact up to 2 wt % gabapentin, whereas the lamellar phase coexisted with the hexagonal one in the concentration range of 3-4 wt % of the drug. At gabapentin content of 5-6 wt %, only lamellar phases containing defects such as dislocations and multilamellar vesicles were detected. Incorporation of GBP decreased the lattice parameter of the H(II) mesophase from 56.6 to 50.6 Å, while the structural dimensions of the lamellar phase were not affected. ATR-FTIR analysis suggested enhanced hydrogen bonding between the protonated amine of GBP and the O-H groups of the GMO and the water surrounding in the inner hydrophilic interface region. This led to intercalation of the drug into the water-lipid interface. At higher GBP loads of 4-6 wt %, thermal analysis revealed disordering within the lipid packing, apparently induced by the spatially altered interface area. Rheological measurements correlated the macroscopic features of the systems with alterations on the molecular level and allowed distinguishing between closely related mesophases due to their different rheological characteristics. In vitro transdermal delivery studies showed that the examined mesophases enabled a sustained release of GBP compared to its aqueous solution. Sustained release was more pronounced in the case of the hexagonal mesophase, compared to the lamellar one.

  5. Effect of optical purity on the critical heat capacity at the smectic-A-(chiral)-smectic-C transition in an antiferroelectric liquid crystal

    PubMed

    Ema; Kanai; Yao; Takanishi; Takezoe

    2000-02-01

    High resolution ac calorimetric measurements have been carried out near the smectic-A-chiral-smectic-C phase transition in the antiferroelectric liquid crystal 4-(1-methylheptyloxycarbonyl)phenyl 4(')-octyloxybiphenyl-4-carboxylate (MHPOBC). Data on samples with different optical purities have been analyzed in detail using a renormalization-group expression with corrections-to-scaling terms. The chiral-smectic-C(alpha)-chiral-smectic-C phase transition is first order, while the smectic-A-chiral-smectic-C(alpha) phase transition is second order. A direct smectic-A-chiral-smectic-C phase transition, which occurs in near-racemic mixtures, was found to be quasitricritical and weakly first order. This implies that the smectic-A-smectic-C transition in the racemate locates at a special point where four critical lines intersect.

  6. Smectic-Calpha*-smectic-C* phase transition and critical point in binary mixtures.

    PubMed

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

    2006-09-01

    We have investigated the smectic-Calpha*-smectic-C* (SmCalpha*-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 interactions are present in the SmCalpha*-SmC* critical region.

  7. Electro-optic and dielectric study of the de Vries-type smectic-A* phase exhibiting transitions to smectic-C*A and smectic-C* phases.

    PubMed

    Manna, U; Song, Jang-Kun; Panarin, Yu P; Fukuda, Atsuo; Vij, J K

    2008-04-01

    Mixtures of different compositions of an antiferroelectric liquid crystal compound that exhibits direct smectic-A*(Sm-A*)-smectic-C*(A) (Sm-C*(A)) transition with a ferroelectric liquid crystal compound that exhibits Sm-A*-smectic-C*(Sm-C*) transition are studied using electro-optics and dielectric spectroscopy. The results of optical texture, birefringence, and the tilt angle suggest that a part of the Sm-A* phase is of de Vries type, since an increase in the tilt angle with decreasing temperature results in a reduction in the value of the birefringence in the Sm-A* phase, whereas the birefringence at Sm-A* to Sm-C* transition goes up by 12.7%. The soft mode relaxation strength, the Landau coefficient of the temperature dependent term, and the other related parameters of the de Vries-type Sm-A-Sm-C*(A) and Sm-A*-Sm-C* transitions are determined using the Landau theory of the second-order phase transition. For the Sm-A*-Sm-C* transition, we find that the soft mode relaxation strength decreases, the Landau coefficient increases, and the Curie-Weiss temperature range decreases with an increased ferroelectric composition in the mixture. These observations can be explained by assuming that with increased ferroelectric composition in the mixture, the layer shrinkage at the de Vries Sm-A*-Sm-C* transition increases. On comparing the results of de Vries-type Sm-A* to Sm-C*(A) and Sm-C* transitions, we find that the soft mode dielectric strength and the other related Landau parameters of the de Vries Sm-A* phase are of the same order of magnitude for transitions from Sm-A* to Sm-C* and to Sm-C*(A) except for the composition of the mixture where both Sm-C* and Sm-C*(A) transitions are stable and the phase diagram shows phase sequence Sm-A* to Sm-C* to Sm-C*(A).

  8. Multistability in the mixtures of smectic-C^{*} materials with compensated twisting power.

    PubMed

    Emelyanenko, A V; Pozhidaev, E P

    2016-04-01

    The effect of multistability in the mixtures of smectic-C^{*} materials with compensated twisting power, i.e., the existence of a large number of almost equiprobable states in the same mixture under the same conditions, is analyzed in the framework of elastic continuum theory. A simple molecular model is also considered. It is shown that multistability can follow from the bulk properties of the smectic-C^{*} materials with compensated twisting power, but with high spontaneous polarization. Multistability leads to the formation of ferroelectric domains, in which the director oscillates in space. The length and amplitude of this oscillation is tunable smoothly by an electric field. Theoretical results for the domain length agree completely with the experimental data. A suggestion is made as to why each domain structure is remembered without the energy consumption, when the electric field is abruptly switched off. The structural dependence on material parameters, such as the spontaneous polarization, the elastic constant, and the equilibrium wave number, is predicted. PMID:27176364

  9. Multistability in the mixtures of smectic-C* materials with compensated twisting power

    NASA Astrophysics Data System (ADS)

    Emelyanenko, A. V.; Pozhidaev, E. P.

    2016-04-01

    The effect of multistability in the mixtures of smectic-C* materials with compensated twisting power, i.e., the existence of a large number of almost equiprobable states in the same mixture under the same conditions, is analyzed in the framework of elastic continuum theory. A simple molecular model is also considered. It is shown that multistability can follow from the bulk properties of the smectic-C* materials with compensated twisting power, but with high spontaneous polarization. Multistability leads to the formation of ferroelectric domains, in which the director oscillates in space. The length and amplitude of this oscillation is tunable smoothly by an electric field. Theoretical results for the domain length agree completely with the experimental data. A suggestion is made as to why each domain structure is remembered without the energy consumption, when the electric field is abruptly switched off. The structural dependence on material parameters, such as the spontaneous polarization, the elastic constant, and the equilibrium wave number, is predicted.

  10. Multistability in the mixtures of smectic-C^{*} materials with compensated twisting power.

    PubMed

    Emelyanenko, A V; Pozhidaev, E P

    2016-04-01

    The effect of multistability in the mixtures of smectic-C^{*} materials with compensated twisting power, i.e., the existence of a large number of almost equiprobable states in the same mixture under the same conditions, is analyzed in the framework of elastic continuum theory. A simple molecular model is also considered. It is shown that multistability can follow from the bulk properties of the smectic-C^{*} materials with compensated twisting power, but with high spontaneous polarization. Multistability leads to the formation of ferroelectric domains, in which the director oscillates in space. The length and amplitude of this oscillation is tunable smoothly by an electric field. Theoretical results for the domain length agree completely with the experimental data. A suggestion is made as to why each domain structure is remembered without the energy consumption, when the electric field is abruptly switched off. The structural dependence on material parameters, such as the spontaneous polarization, the elastic constant, and the equilibrium wave number, is predicted.

  11. 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.

  12. Nanostructure of Edge Dislocations in a Smectic-C* Liquid Crystal.

    PubMed

    Zhang, C; Grubb, A M; Seed, A J; Sampson, P; Jákli, A; Lavrentovich, O D

    2015-08-21

    We report on the first direct nanoscale imaging of elementary edge dislocations in a thermotropic smectic-C* liquid crystal with the Burgers vector equal to one smectic layer spacing d. We find two different types of dislocation profiles. In the dislocation of type A, the layers deformations lack mirror symmetry with respect to the plane perpendicular to the Burgers vector; the dislocation core size is on the order of d. In the dislocation of type S, the core is strongly anisotropic, extending along the Burgers vector over distances much larger (by a factor of 4) than d. The difference is attributed to a different orientation of the molecular tilt plane with respect to the dislocation's axis; the asymmetric layers distortions are observed when the molecular tilt plane is perpendicular to the axis and the split S core is observed when the molecules are tilted along the line.

  13. 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.

  14. Discovery of a novel smectic-C{*} liquid-crystal phase with six-layer periodicity.

    PubMed

    Wang, Shun; Pan, Lidong; Pindak, R; Liu, Z Q; Nguyen, H T; Huang, C C

    2010-01-15

    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{alpha}{*} phase having a helical structure and the SmC{d4}{*} phase with four-layer periodicity. This SmC{d6}{*} phase was identified in two mixtures which have an unusual reversed SmC{d4}{*}-SmC{*} phase sequence. The SmC{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. 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.

  17. Smectic C liquid crystal growth through surface orientation by ZnxCd1-xSe thin films

    NASA Astrophysics Data System (ADS)

    Katranchev, B.; Petrov, M.; Bineva, I.; Levi, Z.; Mineva, M.

    2012-12-01

    A smectic C liquid crystal (LC) texture, consisting of distinct local single crystals (DLSCs) was grown using predefined orientation of ternary nanocrystalline thin films of ZnxCd1-xSe. The surface morphology and orientation features of the ZnxCd1-xSe films were investigated by AFM measurements and micro-texture polarization analysis. The ZnxCd1-xSe surface causes a substantial enlargement of the smectic C DLSCs and induction of a surface bistable state. The specific character of the morphology of this coating leads to the decrease of the corresponding anchoring energy. Two new chiral states, not typical for this LC were indicated. The physical mechanism providing these new effects is presented.

  18. Uniaxial alignment of nanoconfined columnar mesophases.

    PubMed

    Mouthuy, Pierre-Olivier; Melinte, Sorin; Geerts, Yves H; Jonas, Alain M

    2007-09-01

    By confining discotic phthalocyanines in a network of crisscrossed nanogrooves, we obtain a uniaxial alignment of the columnar mesophase. The alignment process is based on the anisotropy of interface tension between the mesophase and the nanogrooves' walls. Preferential mesophase alignment results from this nonhomogeneity combined with the anisotropy of the network cell dimensions. A simple model is proposed to explain the experimental observations.

  19. Constant molecular rotation at the smectic-A to smectic-C* transition in ferroelectric liquid crystals

    NASA Astrophysics Data System (ADS)

    Kremer, F.; Vallerien, S. U.; Kapitza, H.; Zentel, R.; Fischer, E. W.

    1990-09-01

    We present dielectric measurements extended over the frequency range from 106 to 109 Hz on a pure ferroelectric liquid crystal. In clear contrast to the generally attributed origin of the ferroelectricity in liquid crystals arising from a slowing down of the molecular rotation around the long molecular axis, we find by direct observation the corresponding dielectric relaxation unchanged at the smectic-A to smectic-C* transition. This result requires a new interpretation of a recently published degenerate four-wave-mixing experiment by Lalanne et al. [Phys. Rev. Lett. 62, 3046 (1989)].

  20. Optical studies of the smectic-C{sub {alpha}}{sup *} phase layer structure in free-standing films

    SciTech Connect

    Olson, D. A.; Pankratz, S.; Johnson, P. M.; Cady, A.; Nguyen, H. T.; Huang, C. C.

    2001-06-01

    The layer structure of the smectic-C{sub {alpha}}{sup *} phase of one liquid-crystal compound has been acquired from both differential optical reflectivity and ellipsometry measurements in the free-standing film geometry. The data from both techniques display characteristic oscillations as a function of temperature, which can be described by a model for the film consisting of surface anticlinic layers and an interior short-pitched azimuthal helix. These results are consistent with those found previously for another compound. Depolarized reflected light microscopy is used to study the films when the unique features of the aforementioned oscillations occur.

  1. 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.

  2. CdSe nanoparticles dispersed in ferroelectric smectic liquid crystals: effects upon the smectic order and the smectic-A to chiral smectic-C phase transition.

    PubMed

    Thanassoulas, Angelos; Karatairi, Eva; Cordoyiannis, George; Kutnjak, Zdravko; Tzitzios, Vassilios; Lelidis, Ioannis; Nounesis, George

    2013-09-01

    Spherical CdSe nanoparticles, surface-treated with oleylamine and tri-octylphosphine, dispersed in ferroelectric liquid crystals, can efficiently target disclination lines, substantially altering the macroscopic properties of the host compound. Here we present an ac calorimetry and x-ray diffraction study demonstrating that for a large range of nanoparticle concentrations the smectic-A layer thickness increases monotonically. This provides evidence for enhanced accumulation of nanoparticles at the smectic layers. Our results for the Smectic-A (SmA) to chiral smectic-C (SmC) phase transition of the liquid crystal S-(+)4-(2'-methylbutyl)phenyl-4'-n-octylbiphenyl-4-carboxylate (CE8) reveal that the character of the transition is profoundly changed as a function of the nanoparticle concentration. Large transition temperature shifts are recorded. Moreover, the heat-capacity peaks exhibit a crossover trend to a step-like anomaly. This behavior may be linked to the weakening of the SmA and SmC order parameter coupling responsible for the observed near-tricritical, mean-field character of the transition in bulk CE8. At lower temperatures, the presence of nanoparticles disrupts the phase sequence involving the tilted hexatic phases most likely by obstructing the establishment of long-range bond-orientational order.

  3. Transitions induced by solubilized fat into reverse hexagonal mesophases.

    PubMed

    Amar-Yuli, Idit; Garti, Nissim

    2005-06-25

    . In addition, it was found that in tricaprylin/GMO/water systems, the increase in temperature caused a decrease in the lattice parameter. The effect of NaCl on the H(II) mesophase revealed interesting results. At low concentration of tricaprylin (5 wt%), the addition of only 0.1 wt% of NaCl was sufficient to cause the formation of well-defined H(II) mesophase, while further addition of electrolyte increased the hexagonal lattice parameters. At higher TAGs concentrations (10 wt%), addition of electrolyte resulted in the formation of H(II) with modifications of the lattice parameter. All the examined effects were more pronounced with increasing water content.

  4. Elasticity theory of smectic and canonic mesophases

    SciTech Connect

    Stallinga, S.; Vertogen, G. )

    1995-01-01

    The general theory of elasticity for smectic and canonic mesophases is formulated, starting from the assumption that the equilibrium state is spatially periodic. The various surface terms appearing in the deformation free energy density are considered as well. The effective description of the elastic behavior of a general nonchiral smectic mesophase involves one positional elastic constant, 16 bulk orientational elastic constants, and six surface orientational elastic constants. One additional bulk orientational elastic constant is required for the description of a general chiral smectic mesophase. The effective description of the elastic behavior of a general nonchiral canonic mesophase involves six positional elastic constants and three bulk orientational elastic constants. In this case the property of chirality does not introduce additional orientational elastic constants. The elastic constants for some relevant smectic and canonic mesophases are given, including the elastic constants for the antiferroelectric Sm-[ital C][sub [ital A

  5. Leaning-type polar smectic-C phase in a freely suspended bent-core liquid crystal film.

    PubMed

    Chattham, Nattaporn; Tamba, Maria-Gabriela; Stannarius, Ralf; Westphal, Eduard; Gallardo, Hugo; Prehm, Marko; Tschierske, Carsten; Takezoe, Hideo; Eremin, Alexey

    2015-03-01

    A rich variety of responsive behavior occurs in complex structured fluids due to their lower symmetries. On the other hand, fluid disorder tends to increase the symmetry of liquid crystal mesophases. Here, we report direct evidence for the existence of a mesophase with CS symmetry. The observations are based on optical studies of director inversion walls in freely suspended films in electric fields under obliquely incident light. This phase is distinguished by the polarization lying in the molecular tilt plane in freely suspended films. Such a low-symmetry polar fluid phase has been long predicted to occur in bent-core liquid crystals. The stability of this phase is attributed to the bent shape of the mesogens and dominating dispersion interactions.

  6. Dual relaxation and structural changes under uniaxial strain in main-chain smectic-C liquid crystal elastomer.

    PubMed

    Agra-Kooijman, Dena M; Fisch, Michael R; Joshi, Leela; Ren, Wanting; McMullan, Philip J; Griffin, Anselm C; Kumar, Satyendra

    2015-01-01

    The relationship between strain-dependent macroscopic elastic behavior and the changes in microscopic structure of the smectic-C liquid crystal elastomer (LCE), C11MeHQSi8 were investigated using synchrotron X-ray studies. At very low strains ε ≤ 0.2, the smectic layers are randomly oriented. As the strain increases beyond 0.2, the smectic layers reorient and become parallel to the direction of the applied strain. The polydomain to monodomain (P-M) transition accompanied by the formation of chevron structure ensues for ε > 0.2 and is nearly complete for ε = 0.7. The chevron structure relaxes after the applied strain changes, with a time constant τα ∼ 45 min while the orientation order parameters of the mesogenic and elastomeric components gradually increase and saturate at 0.83 and 0.4, respectively at ε = 1.7 which is near the end of the plateau region. Relaxation rates τα for the tilt angle and τd corresponding to the smectic layer spacing both become about 10 times faster when the strain exceeds 0.7. The LCE remains "locked" into the monodomain state and retains 90% and 80% values of α and S, respectively for 24 hours after the applied strain is removed. The viscoelastic properties of the liquid crystal appear to dominate the equilibration process at low strains while the elastomeric properties control the system's response at high strains.

  7. Orientational fluctuations near the smectic A to smectic C phase transition in two "de Vries"-type liquid crystals.

    PubMed

    Nonnenmacher, Dorothee; Jagiella, Stefan; Song, Qingxiang; Lemieux, Robert P; Giesselmann, Frank

    2013-09-16

    On the basis of thorough analysis of 2D X-ray diffraction patterns from smectic monodomains, we examine the influence of orientational fluctuations on the weakly first-order smectic A (SmA) to smectic C (SmC) transitions in two nonchiral organosiloxane "de Vries"-type liquid crystals. We find that these materials exhibit very large molecular tilt fluctuations with magnitudes of up to 35°--thus larger than the average tilt itself. This is essential to understand the underlying molecular mechanism behind the practical absence of smectic layer contraction in these materials: in the SmA phase, the nematic order parameter is very low (molecular fluctuations correspondingly high), and the expected layer shrinkage at the SmA to SmC transition is almost fully compensated by the increase in orientational order, as the fluctuations diminish with decreasing temperature. In addition to the general tilt fluctuations, we observe intrinsic soft-mode fluctuations. They have a λ-shaped temperature dependence that peaks at the SmA-SmC transition with a maximum amplitude of about 2°.

  8. Mesophases in nearly 2D room-temperature ionic liquids.

    PubMed

    Manini, N; Cesaratto, M; Del Pópolo, M G; Ballone, P

    2009-11-26

    Computer simulations of (i) a [C(12)mim][Tf(2)N] film of nanometric thickness squeezed at kbar pressure by a piecewise parabolic confining potential reveal a mesoscopic in-plane density and composition modulation reminiscent of mesophases seen in 3D samples of the same room-temperature ionic liquid (RTIL). Near 2D confinement, enforced by a high normal load, as well as relatively long aliphatic chains are strictly required for the mesophase formation, as confirmed by computations for two related systems made of (ii) the same [C(12)mim][Tf(2)N] adsorbed at a neutral solid surface and (iii) a shorter-chain RTIL ([C(4)mim][Tf(2)N]) trapped in the potential well of part i. No in-plane modulation is seen for ii and iii. In case ii, the optimal arrangement of charge and neutral tails is achieved by layering parallel to the surface, while, in case iii, weaker dispersion and packing interactions are unable to bring aliphatic tails together into mesoscopic islands, against overwhelming entropy and Coulomb forces. The onset of in-plane mesophases could greatly affect the properties of long-chain RTILs used as lubricants. PMID:19886615

  9. Mesophase behavior and rheology of polyhedral particles

    NASA Astrophysics Data System (ADS)

    Agarwal, Umang; Escobedo, Fernando

    2011-03-01

    Translational and orientational excluded volume fields can guide assembly of particles with anisotropic shape to diverse morphologies. A roadmap elucidating correlations between phase behavior and particle shape may help devising efficient strategies for self-assembly of desired nanocrystal superlattices. To explore these complex correlations we performed detailed Monte Carlo simulations of six convex multi-faceted shapes belonging to the diverse class of space-filling polyhedrons. Simulations predict formation of various novel liquid-crystalline and plastic-crystalline phases at intermediate volume fractions. By correlating these findings with particle anisotropy and order of rotational symmetry, simple guidelines for predicting phase behavior of polyhedral particles are proposed. Moreover, detailed analysis of the structures of mesophases reveals importance of dynamical order in defining these phases and preliminary information about kinetics of these transitions is also obtained. Finally, to elucidate the effect of particle shape anisotropy on rheology, preliminary results will be reported from non equilibrium molecular dynamics simulations of the isotropic and cubatic(LC) phase of cuboidal particles. This work was supported by a Department of Energy Basic Energy Science Grant ER46517.

  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. Double Epitaxy as a Paradigm for Templated Growth of Highly Ordered Three-Dimensional Mesophase Crystals.

    PubMed

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

    2016-09-27

    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. This 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 the material's three-dimensional architecture achieved in this one-step synthesis is reminiscent of that in biomineralization.

  12. Induced Mesophase in Mixtures of Photopolymerizable Hyperbranched Polyester and Liquid Crystal Mesogen

    NASA Astrophysics Data System (ADS)

    Kim, Namil; Kyu, Thein; Nosaka, Mami; Kudo, Hiroto; Nishikubo, Tadatomi

    2008-03-01

    Phase behavior of a mixture of eutectic liquid crystals (E7) and hyperbranched polyester (HBPEAc-COOH) has been investigated using polarized optical microscopy and differential scanning calorimetry. The observed phase diagram is an upper azeotrope, exhibiting the coexistence of nematic + isotropic phase in the vicinity of 90˜110^oC above the clearing temperature of neat E7 (60^oC). With decreasing temperature a focal-conic fan shaped texture develops in the composition range of 70˜90 wt% of E7, suggestive of induced smectic Sm-A phase in the mixture containing no known smectic phase in their neat forms. Wide angle x-ray diffraction (WAXD) technique revealed the existence of higher order mesophase(s). The phenomenon of induced mesophase in the hyperbranched polyester/E7 system will be discussed.

  13. Double Epitaxy as a Paradigm for Templated Growth of Highly Ordered Three-Dimensional Mesophase Crystals.

    PubMed

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

    2016-09-27

    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. This 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 the material's three-dimensional architecture achieved in this one-step synthesis is reminiscent of that in biomineralization. PMID:27576108

  14. Calorimetric study of the nematic to smectic- A and smectic- A to smectic- C phase transitions in liquid-crystal-aerosil dispersions

    NASA Astrophysics Data System (ADS)

    Roshi, A.; Iannacchione, G. S.; Clegg, P. S.; Birgeneau, R. J.; Neubert, M. E.

    2005-11-01

    A high-resolution calorimetric study has been carried out on nanocolloidal dispersions of aerosils in the liquid crystal 4-n -pentylphenylthiol- 4'-n -octyloxybenzoate (8¯S5) as a function of aerosil concentration and temperature spanning the smectic- C to nematic phases. Over this temperature range, this liquid crystal possesses two continuous XY phase transitions: a fluctuation-dominated nematic to smectic- A transition with α≈αXY=-0.013 and a mean-field smectic- A to smectic- C transition. The effective critical character of the N-SmA transition remains unchanged over the entire range of the introduced quenched random disorder while the peak height and enthalpy can be well described by considering a cutoff length scale to the quasicritical fluctuations. The robust nature of the N-SmA transition in this system contrasts with cyanobiphenyl-aerosil systems and may be due to the mesogens being nonpolar and having a long nematic range. The character of the SmA-SmC transition changes gradually with increasing disorder but remains mean field like. The heat capacity maximum at the SmA-SmC transition scales as ρS-0.5 with an apparent evolution from tricritical to a simple mean-field step behavior. These results may be generally understood as a stiffening of the liquid crystal (both the nematic elasticity as well as the smectic layer compression modulus B ) with silica density.

  15. Hydrophilic nanoparticles stabilising mesophase curvature at low concentration but disrupting mesophase order at higher concentrations.

    PubMed

    Beddoes, Charlotte M; Berge, Johanna; Bartenstein, Julia E; Lange, Kathrin; Smith, Andrew J; Heenan, Richard K; Briscoe, Wuge H

    2016-07-13

    Using high pressure small angle X-ray scattering (HP-SAXS), we have studied monoolein (MO) mesophases at 18 wt% hydration in the presence of 10 nm silica nanoparticles (NPs) at NP-lipid number ratios (ν) of 1 × 10(-6), 1 × 10(-5) and 1 × 10(-4) over the pressure range 1-2700 bar and temperature range 20-60 °C. In the absence of the silica NPs, the pressure-temperature (p-T) phase diagram of monoolein exhibited inverse bicontinuous cubic gyroid (Q), lamellar alpha (Lα), and lamellar crystalline (Lc) phases. The addition of the NPs significantly altered the p-T phase diagram, changing the pressure (p) and the temperature (T) at which the transitions between these mesophases occurred. In particular, a strong NP concentration effect on the mesophase behaviour was observed. At low NP concentration, the p-T region pervaded by the Q phase and the Lα-Q mixture increased, and we attribute this behaviour to the NPs forming clusters at the mesophase domain boundaries, encouraging transition to the mesophase with a higher curvature. At high NP concentrations, the Q phase was no longer observed in the p-T phase diagram. Instead, it was dominated by the lamellar (L) phases until the transition to a fluid isotropic (FI) phase at 60 °C at low pressure. We speculate that NPs formed aggregates with a "chain of pearls" structure at the mesophase domain boundaries, hindering transitions to the mesophases with higher curvatures. These observations were supported by small angle neutron scattering (SANS) and scanning electron microscopy (SEM). Our results have implications to nanocomposite materials and nanoparticle cellular entry where the interactions between NPs and organised lipid structures are an important consideration. PMID:27340807

  16. Crystallizing Transmembrane Peptides in Lipidic Mesophases

    SciTech Connect

    Höfer, Nicole; Aragão, David; Caffrey, Martin

    2011-09-28

    Structure determination of membrane proteins by crystallographic means has been facilitated by crystallization in lipidic mesophases. It has been suggested, however, that this so-called in meso method, as originally implemented, would not apply to small protein targets having {le}4 transmembrane crossings. In our study, the hypothesis that the inherent flexibility of the mesophase would enable crystallogenesis of small proteins was tested using a transmembrane pentadecapeptide, linear gramicidin, which produced structure-grade crystals. This result suggests that the in meso method should be considered as a viable means for high-resolution structure determination of integral membrane peptides, many of which are predicted to be coded for in the human genome.

  17. 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.

  18. Molecular interactions in reverse hexagonal mesophase in the presence of Cyclosporin A.

    PubMed

    Libster, Dima; Ishai, Paul Ben; Aserin, Abraham; Shoham, Gil; Garti, Nissim

    2009-02-01

    The present work investigates the detailed molecular structure of the H(II) mesophase of GMO/tricaprylin/phosphatidylcholine/water system in the presence of hydrophobic model peptide Cyclosporin A (CSA) via ATR-FTIR analysis. The conformation of the peptide in the hexagonal mesophase, as well as its location and specific interactions with the components of the carrier, were studied. Incorporation of phosphatidylcholine to the ternary GMO/tricaprylin/water system caused competition for water binding between the hydroxyl groups of GMO and the phosphate groups of the phosphatidylcholine (PC) leading to dehydration of the GMO hydroxyls in favor of phospholipid hydration. Analysis of CSA solubilization effect on the H(II) mesophase revealed a significant increase in the strength of hydrogen bonding with surfactant hydrogen-bonded carbonyls, indicating interaction of the peptide with the CO groups of the surfactants. The peptide probably caused partial replacement of the intramolecular hydrogen bonds of the mesophase carbonyl groups with intermolecular hydrogen bonds of these carbonyl groups with the peptide. Furthermore, analysis of the Amide I' peak in the FTIR spectra of the peptide demonstrated that two pairs of its internal hydrogen bonds are disrupted when it is incorporated. The partial disruption of the internal hydrogen bonds seems to cause an outward rotation of the peptide amide groups involved, resulting in more efficient intermolecular hydrogen-bonding ability. Apparently, this conformational change increased the hydrophilic properties of CSA, even making it susceptible to a weak interaction with the GMO hydroxyl groups in the interfacial region.

  19. Behavior of the layer compression elastic modulus near, above, and below a smectic C-hexatic I critical point in binary mixtures.

    PubMed

    Rogez, D; Benguigui, L G; Martinoty, P

    2005-02-01

    We present the first study of the layer compression modulus B carried out near, above and below the Smectic C-Hexatic I critical point in racemic mixtures of methylbutyl phenyl octylbiphenyl-carboxylate (8SI) and the octyloxy biphenyl analog (8OSI), at frequencies ranging from 0.2 Hz to 2 x 10(3) Hz. The behavior of B as a function of temperature shows a progressive evolution from a first order transition in 8SI to a continuous supercritical behavior in 8OSI. The latter is characterized by an increase in B, which appears above the transition, and which is followed by a leveling off when the temperature is decreased towards the transition. It is proposed that this behavior stems from the relaxation of the hexatic domains which are frozen in the frequency range studied. For the supercritical and near-critical compounds, B exhibits a small dip near the transition temperature, which is visible in the low frequency range only, indicating that the dynamics associated with the critical point is very slow. We also report measurements in the Crystal-J phase of the pure compounds, and show that 8SI behaves mechanically as a hexatic phase and 8OSI as a soft crystal phase.

  20. Unit cell structure of water-filled monoolein in inverted hexagonal mesophase in the presence of incorporated tricaprylin and entrapped lysozyme.

    PubMed

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

    2016-03-01

    Molecular dynamics (MD) was employed by means of a specific simulation protocol to investigate the equilibrium structure at 25 °C of the hexagonal inverted (HII) mesophase composed from water, 1-monoolein (GMO), and tricaprylin, with or without entrapped lysozyme. Based on robust and fast MD simulations, the study provides a comprehensive analysis and visualization of the local structure of HII mesophase containing admixtures. The most important physical insight is the possibility to observe the strong self-recovery capacity of the GMO layer, which allows the HII mesophase tubes to reorganize and host lysozyme molecules with a size bigger than the diameter of the water channel. This is a direct message to the experimenters that the HII mesophase has the potential to host molecules larger than the diameter of the water channel. Collective character of the interlipid interactions is outlined, which is not affected by the presence of the cargo and may be the reason for the efficient GMO reorganization. Another important result is the possible explanation of the role of triacylglycerols on the low-temperature stabilization of the HII mesophase. The analysis shows that despite the low amount of tricaprylin, its molecules prevent the extreme inclination of the lipid tails and thus optimize the alignment capacity of the lipid tails layer. The study also reveals that the packing frustration does not depend on the temperature and the presence of admixtures. Hence, it might be numerically defined as a universal invariant parameter of a stable HII mesophase composed of a certain lipid.

  1. 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.

  2. Kinetics and mechanism of the interconversion of inverse bicontinuous cubic mesophases

    NASA Astrophysics Data System (ADS)

    Squires, Adam M.; Templer, R. H.; Seddon, J. M.; Woenkhaus, J.; Winter, R.; Narayanan, T.; Finet, S.

    2005-07-01

    This paper describes time-resolved x-ray diffraction data monitoring the transformation of one inverse bicontinuous cubic mesophase into another, in a hydrated lipid system. The first section of the paper describes a mechanism for the transformation that conserves the topology of the bilayer, based on the work of Charvolin and Sadoc, Fogden and Hyde, and Benedicto and O’Brien in this area. We show a pictorial representation of this mechanism, in terms of both the water channels and the lipid bilayer. The second section describes the experimental results obtained. The system under investigation was 2:1 lauric acid: dilauroylphosphatidylcholine at a hydration of 50% water by weight. A pressure-jump was used to induce a phase transition from the gyroid (QIIG) to the diamond (QIID) bicontinuous cubic mesophase, which was monitored by time-resolved x-ray diffraction. The lattice parameter of both mesophases was found to decrease slightly throughout the transformation, but at the stage where the QIID phase first appeared, the ratio of lattice parameters of the two phases was found to be approximately constant for all pressure-jump experiments. The value is consistent with a topology-preserving mechanism. However, the polydomain nature of our sample prevents us from confirming that the specific pathway is that described in the first section of the paper. Our data also reveal signals from two different intermediate structures, one of which we have identified as the inverse hexagonal (HII) mesophase. We suggest that it plays a role in the transfer of water during the transformation. The rate of the phase transition was found to increase with both temperature and pressure-jump amplitude, and its time scale varied from the order of seconds to minutes, depending on the conditions employed.

  3. Mesophase Separation and Probe Dynamics in Protein-Polyelectrolyte Coacervates

    NASA Astrophysics Data System (ADS)

    Kayitmazer, A. Basak; Bohidar, H. B.; Mattison, K. W.; Bose, A.; Russo, P. S.; Dubin, P. L.

    2007-03-01

    Protein-PE coacervates (PPC's) are self-assembling monophasic biomacromolecular fluids whose unique properties arise from transient heterogeneities. Among these properties are: high viscosity coupled with anomalously high protein diffusivity; rheological behavior intermediate between viscous solutions and gels; and little perturbation of protein native state. Despite their discovery 50 years ago, structure of coacervates is still poorly understood. Among the two models suggested for coacervate structure so far, we have verified the validity of one that proposes two states for protein in the coacervate. Cryo-TEM and static light scattering experiments on bovine serum albumin-poly(diallydimethylammonium chloride) coacervates have revealed heterogeneous scattering centers of several hundred nm, consistent with the presence of partially inter-connected dense domains surrounded by a large proportion of dilute domains, inferred from rheology. Fluorescence photobleaching recovery measurements of protein self-diffusion in coacervates have revealed temporal and spatial mesophasic heterogeneities over broad time and length scales; i.e. 50-700 nm and 0.5-30 sec.

  4. 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

    2010-03-01

    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)).

  5. Unit cell structure of water-filled monoolein in inverted hexagonal mesophase in the presence of incorporated tricaprylin and entrapped lysozyme.

    PubMed

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

    2016-03-01

    Molecular dynamics (MD) was employed by means of a specific simulation protocol to investigate the equilibrium structure at 25 °C of the hexagonal inverted (HII) mesophase composed from water, 1-monoolein (GMO), and tricaprylin, with or without entrapped lysozyme. Based on robust and fast MD simulations, the study provides a comprehensive analysis and visualization of the local structure of HII mesophase containing admixtures. The most important physical insight is the possibility to observe the strong self-recovery capacity of the GMO layer, which allows the HII mesophase tubes to reorganize and host lysozyme molecules with a size bigger than the diameter of the water channel. This is a direct message to the experimenters that the HII mesophase has the potential to host molecules larger than the diameter of the water channel. Collective character of the interlipid interactions is outlined, which is not affected by the presence of the cargo and may be the reason for the efficient GMO reorganization. Another important result is the possible explanation of the role of triacylglycerols on the low-temperature stabilization of the HII mesophase. The analysis shows that despite the low amount of tricaprylin, its molecules prevent the extreme inclination of the lipid tails and thus optimize the alignment capacity of the lipid tails layer. The study also reveals that the packing frustration does not depend on the temperature and the presence of admixtures. Hence, it might be numerically defined as a universal invariant parameter of a stable HII mesophase composed of a certain lipid. PMID:26424533

  6. Mesoporous organosilicas with ultra-large pores: mesophase transformation and bioadsorption properties.

    PubMed

    Na, Wei; Wei, Qi; Zou, Ze-Chang; Li, Qun-Yan; Nie, Zuo-Ren

    2010-06-01

    Large pore ordered mesoporous organosilicas (OMOs) with distinct mesophase structure was synthesized under low temperatures by the co-condensation of 1,2bis(triethoxysilyl)ethane (BTESE) and tetraethyl orthosilicate (TEOS) in acidic solution, using triblock copolymer F127 as a template and 1,3,5-trimethylbenzene (TMB) as a swelling agent. With the decrease of temperature, a mesophase transformation from 2D hexagonal structure (p6mm) via mesostructured cellular foam to a highly ordered 3D cubic structure (Fm3m) was evidenced by small angle X-ray diffraction (SAXS), transmission electron microscopy (TEM) and N(2) sorption. It reveals that the lower synthesis temperatures may influence the hydrolysis and condensation of silica species and the hydrophilic-hydrophobic property of F127, as well as the swelling capacity of F127 micelles with TMB, which resulting in a formation of large pores ordered mesoporous organosilicas with various mesostructures materials. Finally, the enzyme adsorption properties of the OMOs were investigated and the results showed that the OMOs with a 3D large pore structure and regular morphology is much more qualified for enzyme adsorption.

  7. 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.

  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. Charge-carrier transport in smectic mesophases of biphenyls

    NASA Astrophysics Data System (ADS)

    Ohno, Akira; Haruyama, Akihide; Kurotaki, Kensuke; Hanna, Jun-ichi

    2007-10-01

    The charge-transport properties of ω ,ω'-alkylalkoxylbiphenyls, one of the simplest calamitic (rodlike) liquid crystals exhibiting smectic mesophases, were investigated using the time-of-flight experiments. A mobility of ˜10-3 cm2/V s was determined for holes in both smectic B (SmB) and smectic E (SmE) phases. This high electronic mobility, comparable to the highest mobilities in amorphous organic semiconductors, indicates that the self-organization of such simple molecules including small aromatic compounds is quite effective in enhancing the charge transport in organic materials. The mobilities of both smectic mesophases, however, depend on temperatures, which is not the case for other typical smectic liquid crystals reported previously. Interestingly, the mobility in the SmE phase exhibits a Poole-Frenkel type of field dependence. Detailed experimental studies have shown that this field dependence is not due to the trapping effect of carriers caused by chemical contaminants or structural defects such as domain boundaries and dislocation, but arises from the widely distributed density of states with a distribution width of 0.11-0.13 eV for the SmE phase, as estimated based on a two-dimensional Gaussian disorder model. The phase-specific carrier transport in biphenyls may provide us with unique insights leading to a more complete understanding of the charge carrier transport in the mesophase materials.

  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. Low viscosity reversed hexagonal mesophases induced by hydrophilic additives.

    PubMed

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

    2008-04-01

    This study reports on the formation of a low viscosity H(II) mesophase at room temperature upon addition of Transcutol (diethylene glycol mono ethyl ether) or ethanol to the ternary mixture of GMO (glycerol monooleate)/TAG (tricaprylin)/water. The microstructure and bulk properties were characterized in comparison with those of the low viscosity HII mesophase formed in the ternary GMO/TAG/water mixture at elevated temperatures (35-40 degrees C). We characterized the role of Transcutol or ethanol as inducers of disorder and surfactant mobility. The techniques used were rheology, 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 incorporation of either Transcutol or ethanol induced the formation of less ordered HII mesophases with smaller domain sizes and lattice parameters at room temperature (up to 30 degrees C), similar to those found for the GMO/TAG/water mixture at more elevated temperatures (35-40 degrees C). On the basis of our measurements, we suggest that Transcutol or ethanol causes dehydration of the GMO headgroups and enhances the mobility of the GMO chains. As a result, these two small molecules, which compete for water with the GMO polar headgroups, may increase the curvature of the cylindrical micelles and also perhaps reduce their length. This results in the formation of fluid H(II) structures at room temperature (up to 30 degrees C). It is possible that these phases are a prelude to the H(II)-L(2) transformation, which takes place above 35 degrees C.

  12. 23Na NMR study of ionic mesophases in molten sodium carboxylates

    NASA Astrophysics Data System (ADS)

    Bonekamp, J.; Eguchi, T.; Jonas, J.

    1980-10-01

    The 23Na NMR lineshapes are reported for the ionic mesophase and isotropic phase of the melts of sodium n-butyrate and sodium isovalerate. The powder pattern for the central transition typical for the second-order quadrupole effect observed in the mesophase melts is of particular interest. Some analogies to 23Na behavior in sodium β-alumina are pointed out.

  13. 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.

  14. Large-amplitude motion in polymer crystals and mesophases

    SciTech Connect

    Wunderlich, B. |

    1994-12-31

    Large-amplitude motion of macromolecules involves mainly rotation about bonds (conformational motion). In the liquid phases, the large- amplitude motion is coupled with disorder and accounts for the flow and viscoelastic behavior. Perfectly ordered crystals, in contrast, permit only little large-amplitude motion. The mesophases are intermediate in order and mobility. In crystals, large-amplitude motion leads initially to gauche defects and kinks (conformational defects), and ultimately may produce conformationally disordered crystals (conis crystals). Molecular dynamics simulations of crystals with up to 30,000 atoms have been carried out and show the mechanism of defect formation, permit the study of the distribution of defects, and the visualization of hexagonal crystals. Distinction between main-chain liquid-crystalline macromolecules and condis crystals, the two mesophases of polymers, can be done on basis of analysis of phase separation (partial crystallinity), present in condis crystals and not in liquid crystals. Solid state NMR is the tool of choice for detecting mobile and rigid phases. In highly drawn fibers one can find four different states of order and mobility. Besides the (defect) crystalline phase and the isotropic amorphous phase, an intermediate oriented phase and a rigid amorphous phase exists.

  15. Nonionic-anionic mixed surfactants cubic mesophases. Part I: Structural chaotropic and kosmotropic effect.

    PubMed

    Efrat, Rivka; Abramov, Zoya; Aserin, Abraham; Garti, Nissim

    2010-08-26

    We prepared and investigated cubic bicontinuous (V) phase from mixtures of nonionic monoolein (GMO) and anionic oleyl lactate (OL) surfactants in the presence of ethanol and water. The isotropic region and the composition of the V phase in the pseudoternary phase diagram vary with the nature of the hydrophilic headgroups and their charge. We examined three anionic species, acidic (HOL), partially neutralized (OL), and totally ionized (NaOL) forms. The largest swollen V region within the phase diagram was formed from the partially neutralized form. The V formation is dependent on the GMO/OL ratio. The largest isotropic region in the phase diagrams was found with GMO/OL at a 70:30 wt % ratio and in the presence of 5.0 and 38.5 wt % ethanol and water, respectively. The structural effect of OL was determined by small-angle X-ray spectroscopy, differential scanning calorimetry, and Fourier transform infrared. The results revealed that the structure is curvature-dependent. Mesophases made from 90:10 wt % GMO/OL showed phase transition from gyroid (G) to diamond (D) symmetry. Preparations made from 30:70 wt % GMO/OL exhibited coexistence of two mesophases, one (of low order) cubic and the other lamellar. Because of the overall gauche deformation growth, the hydrocarbon order decreased with the OL content increase. The GMO, sn(2) and sn(3) headgroups, and water structure vibration bands indicate a chaotropic effect as a result of the interdigitation of OL anions and Na(+) and H(+) counterions.

  16. 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.

  17. 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.

  18. 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

  19. Effects of detergent β-octylglucoside and phosphate salt solutions on phase behavior of monoolein mesophases.

    PubMed

    Khvostichenko, Daria S; Ng, Johnathan J D; Perry, Sarah L; Menon, Monisha; Kenis, Paul J A

    2013-10-15

    Using small-angle x-ray scattering (SAXS), we investigated the phase behavior of mesophases of monoolein (MO) mixed with additives commonly used for the crystallization of membrane proteins from lipidic mesophases. In particular, we examined the effect of sodium and potassium phosphate salts and the detergent β-octylglucoside (βOG) over a wide range of compositions relevant for the crystallization of membrane proteins in lipidic mesophases. We studied two types of systems: 1), ternary mixtures of MO with salt solutions above the hydration boundary; and 2), quaternary mixtures of MO with βOG and salt solutions over a wide range of hydration conditions. All quaternary mixtures showed highly regular lyotropic phase behavior with the same sequence of phases (Lα, Ia3d, and Pn3m) as MO/water mixtures at similar temperatures. The effects of additives in quaternary systems agreed qualitatively with those found in ternary mixtures in which only one additive is present. However, quantitative differences in the effects of additives on the lattice parameters of fully hydrated mesophases were found between ternary and quaternary mixtures. We discuss the implications of these findings for mechanistic investigations of membrane protein crystallization in lipidic mesophases and for studies of the suitability of precipitants for mesophase-based crystallization methods.

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

    DOE PAGESBeta

    Stappert, Kathrin; Ünal, 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 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

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

    SciTech Connect

    Stappert, Kathrin; Ünal, 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.

  2. 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.

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

    DOE PAGESBeta

    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 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

  4. 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.

  5. 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.

  6. 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.

  7. 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. PMID:20189781

  8. 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.

  9. 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.

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

    DOE PAGESBeta

    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-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

  11. 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.

  12. 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

  13. 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.

  14. Fast acquisition of multidimensional NMR spectra of solids and mesophases using alternative sampling methods.

    PubMed

    Lesot, Philippe; Kazimierczuk, Krzysztof; Trébosc, Julien; Amoureux, Jean-Paul; Lafon, Olivier

    2015-11-01

    Unique information about the atom-level structure and dynamics of solids and mesophases can be obtained by the use of multidimensional nuclear magnetic resonance (NMR) experiments. Nevertheless, the acquisition of these experiments often requires long acquisition times. We review here alternative sampling methods, which have been proposed to circumvent this issue in the case of solids and mesophases. Compared to the spectra of solutions, those of solids and mesophases present some specificities because they usually display lower signal-to-noise ratios, non-Lorentzian line shapes, lower spectral resolutions and wider spectral widths. We highlight herein the advantages and limitations of these alternative sampling methods. A first route to accelerate the acquisition time of multidimensional NMR spectra consists in the use of sparse sampling schemes, such as truncated, radial or random sampling ones. These sparsely sampled datasets are generally processed by reconstruction methods differing from the Discrete Fourier Transform (DFT). A host of non-DFT methods have been applied for solids and mesophases, including the G-matrix Fourier transform, the linear least-square procedures, the covariance transform, the maximum entropy and the compressed sensing. A second class of alternative sampling consists in departing from the Jeener paradigm for multidimensional NMR experiments. These non-Jeener methods include Hadamard spectroscopy as well as spatial or orientational encoding of the evolution frequencies. The increasing number of high field NMR magnets and the development of techniques to enhance NMR sensitivity will contribute to widen the use of these alternative sampling methods for the study of solids and mesophases in the coming years.

  15. 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%.

  16. From antiferroelectricity to ferroelectricity in smectic mesophases formed by bent-core molecules

    NASA Astrophysics Data System (ADS)

    Tschierske, Carsten; Dantlgraber, Gert

    2003-08-01

    This contribution gives an overview of ferroelectric switching liquid crystalline phases formed by bent-core molecules. First a description of some general principles behind the mesophase formation within bent-core systems will be given, followed by a short review of the mesophase structures formed by such molecules. Then, different classes of ferroelectric switching bent-core mesogens will be described. This type of switching behaviour has been reported for several subtypes of polar smectic phases (B2, B5, B7 and SmCG) and recently for columnar mesophases. In this discussion particular attention will be made to polyphilic bent-core molecules, composed of three incompatible units, a bent aromatic core, alkyl chains and an oligosiloxane unit. The importance of the decoupling of the layers into microsegregated sublayers for the ferroelectric organisation is discussed. Many of the ferroelectric switching mesophases show dark textures with distinct regions of opposite chirality in their ground states. It is discussed that this might be due to a helical superstructure formed as a result of an escape from macroscopic polar order. Hence, the materials themselves are not ferroelectric in the ground state, but upon alignment within an electric field in the measuring cells the ferroelectric states are stabilised by surface interactions, leading to a ferroelectric switching system. The designing principle was extended to mesogenic dimers with bent-core structural units. For these compounds, depending on the number of dimethylsiloxane units in the spacer either ferroelectric or antiferroelectric switching was observed, whereby the effect of parity is reversed to that observed for conventional calamitic dimesogens. Finally, a carbosilane-based first generation dendrimer is reported. It shows a ferroelectric switching phase, for which a non-correlated organisation of tilted polar smectic layers is proposed (SmCPR).

  17. The role of glycerol and phosphatidylcholine in solubilizing and enhancing insulin stability in reverse hexagonal mesophases.

    PubMed

    Amar-Yuli, Idit; Azulay, Doron; Mishraki, Tehila; Aserin, Abraham; Garti, Nissim

    2011-12-15

    The potential of reverse hexagonal mesophases based on monoolein (GMO) and glycerol (as cosolvent) to facilitate the solubilization of proteins, such as insulin was explored. H(II) mesophases composed of GMO/decane/water were compared to GMO/decane/glycerol/water and GMO/phosphatidylcholine (PC)/decane/glycerol/water systems. The stability of insulin was tested, applying external physical modifications such as low pH and heat treatment (up to 70°C), in which insulin is known to form ordered amyloid-like aggregates (that are associated with several neurodegenerative diseases) with a characteristic cross β-pleated sheet structure. The impact of insulin confinement within these carriers on its stability, unfolding, and aggregation pathways was studied by combining SAXS, FTIR, and AFM techniques. These techniques provided a better insight into the molecular level of the "component interplay" in solubilizing and stabilizing insulin and its conformational modifications that dictate its final aggregate morphology. PC enlarged the water channels while glycerol shrank them, yet both facilitated insulin solubilization within the channels. The presence of glycerol within the mesophase water channels led to the formation of stronger hydrogen bonds with the hosting medium that enhanced the thermal stability of the protein and remarkably affected the unfolding process even after heat treatment (at 70°C for 60 min).

  18. 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.

  19. 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.

  20. Phospholipid-based self-assembled mesophase systems for light-activated drug delivery.

    PubMed

    Du, Joanne D; Fong, Wye-Khay; Salentinig, Stefan; Caliph, Suzanne M; Hawley, Adrian; Boyd, Ben J

    2015-06-01

    The manipulation of the structure of phospholipid-based mesophases to induce a slow to fast drug release profile has potential for use in therapeutic situations where continuous absorption of drug is not desirable and reduce the frequency of injection for short acting or rapidly cleared drugs in treatments for diseases such as macular degeneration. This study had two aims; firstly to confirm the phase behaviour of 20 mol% cholesterol in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), which was previously reported to transition from lamellar (slow release) to bicontinuous cubic (fast release) phase with increasing temperature. Contrary to the literature, no bicontinuous cubic phase was observed but a transition to the inverse hexagonal phase occurred at all POPE : cholesterol ratios investigated. The second aim was to render these mesophases responsive to near-infrared laser (NIR) irradiation by incorporation of gold nanorods (GNR) incorporated into the POPE system to induce photothermal heating. The inclusion of 3 nM GNR in POPE systems induced reversible disruption of lipid packing equivalent to increasing the temperature to 55 °C when irradiated for 30 s. This study confirmed that although the previously published phase behavior was not correct, GNR and NIR can be used to manipulate the self-assembled mesophases in phospholipid-based systems and highlights the potential for a phospholipid-based light-activated drug delivery system.

  1. Controlling anisotropic drug diffusion in lipid-Fe3O4 nanoparticle hybrid mesophases by magnetic alignment.

    PubMed

    Vallooran, Jijo J; Negrini, Renata; Mezzenga, Raffaele

    2013-01-29

    We present a new strategy to control the anisotropic diffusion of hydrophilic drugs in lyotropic liquid crystals via the dispersion of magnetic nanoparticles in the mesophase, followed by reorientation of the mesophase domains via an external magnetic field. We select a lipid reverse hexagonal phase doped with magnetic iron oxide nanoparticles and glucose and caffeine as model hybrid mesophase and hydrophilic drugs, respectively. Upon cooling through the disorder-order phase transition of the hexagonal phase and under exposure to an external moderate magnetic field (1.1 T), both the nanoparticles and the hexagonal domains align with their columnar axes along the field direction. As a result, the water nanochannels of the inverted hexagonal domains also align parallel to the field direction, leading to a drug diffusion coefficient parallel to the field direction much larger than what was measured perpendicularly: in the case of glucose, for example, this difference in diffusion coefficients approaches 1 order of magnitude. Drug diffusion of the unaligned reverse hexagonal phase, which consists of randomly distributed domains, shows values in between the parallel and transversal diffusion values. This study shows that modifying the overall alignment of anisotropic mesophases via moderate external fields is a valuable means to control the corresponding transport tensor of the mesophase and demonstrates that the orientation of the domains plays an important role in the diffusion process of foreign hydrophilic molecules. PMID:23302008

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

    PubMed

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

    2016-07-01

    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

  3. 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.

  4. 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

  5. Membrane Protein Structure Determination Using Crystallography and Lipidic Mesophases - Recent Advances and Successes

    PubMed Central

    Caffrey, Martin; Li, Dianfan; Dukkipati, Abhiram

    2012-01-01

    The crystal structure of the β2-adrenergic receptor in complex with an agonist and its cognate G protein has just recently been solved. It is now possible to explore in molecular detail the means by which this paradigmatic transmembrane receptor binds agonist, communicates the impulse or signalling event across the membrane and sets in motion a series of G protein-directed intracellular responses. The structure was determined using crystals of the ternary complex grown in a rationally designed lipidic mesophase by the so-called in meso method. The method is proving to be particularly useful in the G protein-coupled receptor field where the structures of thirteen distinct receptor types have been solved in the past five years. In addition to receptors, the method has proven useful with a wide variety of integral membrane protein classes that include bacterial and eukaryotic rhodopsins, a light harvesting complex II (LHII), photosynthetic reaction centers, cytochrome oxidases, β-barrels, an exchanger, and an integral membrane peptide. This attests to the versatility and range of the method and supports the view that the in meso method should be included in the arsenal of the serious membrane structural biologist. For this to happen however, the reluctance in adopting it attributable, in part, to the anticipated difficulties associated with handling the sticky, viscous cubic mesophase in which crystals grow must be overcome. 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. Over the years, we have endeavored to establish how the method works at a molecular level and to make it user-friendly. To these ends, tools for handling the mesophase in the pico- to nano-liter volume range have been developed for highly efficient crystallization screening in manual and robotic modes. Methods have been implemented for evaluating the functional

  6. 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.

  7. Design, synthesis and characterization of a linear hydrogen bonded homologous series

    NASA Astrophysics Data System (ADS)

    Kavitha, C.; Pongali Sathya Prabu, N.; Madhu Mohan, M. L. N.

    2012-03-01

    A linear hydrogen bonded liquid crystalline homologous series has been synthesized and characterized. Hydrogen bond is formed between p-n-dodecyloxy benzoic acid and various p-n-alkyl benzoic acids whose alkyl chain vary from octyl to ethyl. Synthesized complexes are characterized by FTIR, 1H NMR and 13C NMR studies for inferring the formation of hydrogen bonds. Polarizing Optical Microscopy (POM) and DSC studies reveal various mesophases and their corresponding transition temperatures along with respective enthalpy values. All the seven synthesized complexes exhibit rich liquid crystalline mesomorphism. A new phase namely smectic X has been observed in five of the complexes with a narrow thermal range. This phase has been characterized by optical textural, DSC, tilt angle and helicoidal pitch studies. Smectic X is sandwiched between traditional smectic C and re-entrant smectic C (designated as C R) phases. Homeotropic transition in nematic phase is observed in all the mesogens and thus these materials can be used as thermally controlled optical shutters. Tilt angle in smectic C, smectic X and smectic C R phases have been experimentally elucidated for all the mesogens.

  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. 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.

  10. 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.

  11. 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.

  12. Use of a robot for high-throughput crystallization of membrane proteins in lipidic mesophases.

    PubMed

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

    2012-09-01

    Structure-function studies of membrane proteins greatly benefit from having available high-resolution 3-D structures of the type provided through macromolecular X-ray crystallography (MX). An essential ingredient of MX is a steady supply of ideally diffraction-quality crystals. The in meso or lipidic cubic phase (LCP) method for crystallizing membrane proteins is one of several methods available for crystallizing membrane proteins. It makes use of a bicontinuous mesophase in which to grow crystals. As a method, it has had some spectacular successes of late and has attracted much attention with many research groups now interested in using it. One of the challenges associated with the method is that the hosting mesophase is extremely viscous and sticky, reminiscent of a thick toothpaste. Thus, dispensing it manually in a reproducible manner in small volumes into crystallization wells requires skill, patience and a steady hand. A protocol for doing just that was developed in the Membrane Structural & Functional Biology (MS&FB) Group(1-3). JoVE video articles describing the method are available(1,4). The manual approach for setting up in meso trials has distinct advantages with specialty applications, such as crystal optimization and derivatization. It does however suffer from being a low throughput method. Here, we demonstrate a protocol for performing in meso crystallization trials robotically. A robot offers the advantages of speed, accuracy, precision, miniaturization and being able to work continuously for extended periods under what could be regarded as hostile conditions such as in the dark, in a reducing atmosphere or at low or high temperatures. An in meso robot, when used properly, can greatly improve the productivity of membrane protein structure and function research by facilitating crystallization which is one of the slow steps in the overall structure determination pipeline. In this video article, we demonstrate the use of three commercially available

  13. 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.

  14. Liquid-crystalline octopus dendrimers: block molecules with unusual mesophase morphologies.

    PubMed

    Gehringer, Lionel; Bourgogne, Cyril; Guillon, Daniel; Donnio, Bertrand

    2004-03-31

    The synthesis and the mesomorphic properties of several new main-chain liquid-crystalline dendrimers, thereafter designated as octopus dendrimers in accordance with their eight sidearms, are reported. In these dendritic systems, the arborescence is ensured by anisotropic segments, acting as branching cells with a double multiplicity, which are incorporated at every node of the dendritic architecture. In such a way, these compounds radically differ from the classical end-functionalized liquid-crystalline dendrimers, the most commonly reported systems. Following our previous report on purely homolithic systems, that is, the building blocks constituting the dendritic matrix are all identical, several heterolithic systems made of different anisotropic blocks have been prepared. The dendritic branches and corresponding dendrimers were synthesized using a modular construction. Polarized optical microscopy and X-ray diffraction studies showed that all of these new octopus dendrimers exhibit either smectic-like or columnar phases with novel morphologies, the nature of the mesophases depending on the number of terminal chains attached to the peripheral groups. The mesomorphism of these heterolithic dendrimers is discussed in terms of their intrinsic architecture and compared to the analogous homolithic octopus systems. Models for the molecular organizations within both the smectic and the columnar phases are proposed on the basis of small Bragg angle X-ray diffraction studies and are supported by molecular modelizations. Moreover, this study showed that the mesophase stability is very sensitive to the nature and to the mutual arrangement (the spatial location) of the mesogenic segments within the dendritic matrix, illustrating the intimate relationships existing between the mesomorphic properties and the molecular architecture of these dendrimers.

  15. 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

  16. Time resolved WAXS study of the role of mesophase in oriented crysstallisation of poly(ethylene terephthalate-co-isophthalate) copolymers

    SciTech Connect

    Mahendrasingam, A.; Blundell, D. J.; Martin, C.; Urban, Volker S; Narayanan, T.; Fuller, W.

    2005-03-01

    Poly(ethylene terephthalate-co-isophthalate) copolymers containing up to 18 mol% isophalate have been drawn at 90 C at a deformation rate of {approx}15 s{sup -1} while recording two dimensional wide angle X-ray scattering patterns. All polymers, including homopolymer controls, show the development of an oriented smectic mesophase during the last stages of deformation. After the end of deformation, the mesophase decays and is replaced by oriented triclinic crystals which increase according to first order transformation kinetics. The characteristic meridional spacing of the smectic mesophase reduces systematically with increasing isophthalate comonomer and indicates that the comonomer participates in the smectic structure. Unlike isotropic crystallisation from the melt, the crystallinity and crystallisation rate show little variation with comonomer content. This is attributed to the fact that both monomers participate in the intermediate smectic mesophase.

  17. 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

    2013-05-01

    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. PMID:23627902

  18. Highly proton conductive phosphoric acid-nonionic surfactant lyotropic liquid crystalline mesophases and application in graphene optical modulators.

    PubMed

    Tunkara, Ebrima; Albayrak, Cemal; Polat, Emre O; Kocabas, Coskun; Dag, Ömer

    2014-10-28

    Proton conducting gel electrolytes are very important components of clean energy devices. Phosphoric acid (PA, H(3)PO(4) · H2O) is one of the best proton conductors, but needs to be incorporated into some matrix for real device applications, such as into lyotropic liquid crystalline mesophases (LLCMs). Herein, we show that PA and nonionic surfactant (NS, C(12)H(25)(OCH(2)CH(2))(10)OH, C(12)E(10)) molecules self-assemble into PANS-LLCMs and display high proton conductivity. The content of the PANS-LLCM can be as high 75% H(3)PO(4) · H2O and 25% 10-lauryl ether (C(12)H(25)(OCH(2)CH(2))(10)OH, C(12)E(10)), and the mesophase follows the usual LLC trend, bicontinuous cubic (V1)-normal hexagonal (H1)-micelle cubic (I1), by increasing the PA concentration in the media. The PANS-LLCMs are stable under ambient conditions, as well as at high (up to 130 °C) and low (-100 °C) temperatures with a high proton conductivity, in the range of 10(-2) to 10(-6) S/cm. The mesophase becomes a mesostructured solid with decent proton conductivity below -100 °C. The mesophase can be used in many applications as a proton-conducting media as well as a phosphate source for the synthesis of various metal phosphates. As an application, we demonstrate a graphene-based optical modulator using supercapacitor structure formed by graphene electrodes and a PANS electrolyte. A PANS-LLC electrolyte-based supercapacitor enables efficient optical modulation of graphene electrodes over a range of wavelengths, from 500 nm to 2 μm, under ambient conditions.

  19. Host Lipid and Temperature as Important Screening Variables for Crystallizing Integral Membrane Proteins in Lipidic Mesophases. Trials with Diacylglycerol Kinase

    PubMed Central

    Li, Dianfan; Shah, Syed T. A.; Caffrey, Martin

    2013-01-01

    A systematic study of the crystallization of an α-helical, integral membrane enzyme, diacylglycerol kinase, DgkA, using the lipidic cubic mesophase or in meso method is described. These trials have resulted in the production of blocky, rhombohedron-shaped crystals of diffraction quality currently in use for structure determination. Dramatic improvements in crystal quality were obtained when the identity of the lipid used to form the mesophase bilayer into which the protein was reconstituted as a prelude to crystallogenesis was varied. These monoacylglycerol lipids incorporated fatty acyl chains ranging from 14 to 18 carbon atoms long with cis olefinic bonds located toward the middle of the chain. Best crystals were obtained with a lipid that had an acyl chain 15 carbon atoms long with the double bond between carbons 7 and 8. It is speculated that the effectiveness of this lipid derives from hydrophobic mismatch between the target integral membrane protein and the bilayer of the host mesophase. Low temperature (4 °C) worked in concert with the short chain lipid to provide high quality crystals. Recommended screening strategies for crystallizing membrane proteins that include host lipid type and low temperature are made on the basis of this and related in meso crystallization trials. PMID:23956688

  20. 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.

  1. Crystalline-like molecularly ordered mesoporous aluminosilicates derived from aluminosilica-surfactant mesophases via benign template removal.

    PubMed

    Xia, Yongde; Mokaya, Robert

    2006-05-11

    We report the preparation of mesoporous aluminosilicate materials that exhibit molecular-scale ordering in their pore wall framework. The materials were derived from mesoporous aluminosilica-surfactant mesophases via benign template removal methods, which allowed the retention of molecular ordering in surfactant-free materials. The molecularly ordered aluminosilica-surfactant mesophases were obtained from hydrothermal crystallization of cetyltrimethylammonium hydroxide/Al,Si/H2O systems at 135 degrees C for 12 days. Benign template removal via H2O2-mediated oxidation of the surfactant at room temperature was found to be the most effective method in generating surfactant-free materials with molecular ordering, high textural properties (depending on Al content), and high acidity. The Al in the resulting aluminosilicates was entirely incorporated in framework (tetrahedrally coordinated) sites. Template extraction in acidified ethanol also generated molecularly ordered materials but compromised the Al content and acidity. Template removal via conventional calcination generated porous materials with high textural properties but which exhibited only limited molecular ordering and had relatively low acidity and significant amounts of nonframework Al. This work demonstrates that molecular ordering in mesoporous silicate-surfactant mesophases is due to crystallographic ordering within inorganic frameworks rather than the arrangement/packing of surfactant molecules.

  2. Evaporation-Induced Self-Assembly of Hybrid Bridged Silsesquioxane Film and Particulate Mesophases with Integral Organic Functionality

    SciTech Connect

    LU,YUNFENG; FAN,HONGYOU; DOKE,NILESH; LOY,DOUGLAS A.; ASSINK,ROGER A.; LAVAN,DAVID A.; BRINKER,C. JEFFREY

    2000-06-12

    Since the discovery of surfactant-templated silica mesophases, the development of organic modification schemes to impart functionality to the pore surfaces has received much attention. Most recently, using the general class of compounds referred to as bridged silsesquioxanes (RO){sub 3}Si-R{prime}-Si(OR){sub 3} (Scheme 1), three research groups have reported the formation of a new class of poly(bridgedsilsesquioxane) mesophases BSQMs with integral organic functionality. In contrast to previous hybrid mesophases where organic ligands or molecules are situated on pore surfaces, this class of materials necessarily incorporates the organic constituents into the framework as molecularly dispersed bridging ligands. Although it is anticipated that this new mesostructural organization should result in synergistic properties derived from the molecular scale mixing of the inorganic and organic components, few properties of BSQMs have been measured. In addition samples prepared to date have been in the form of granular precipitates, precluding their use in applications like membranes, fluidics, and low k dielectric films needed for all foreseeable future generations of microelectronics.

  3. 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.

  4. Unit cell structure of water-filled monoolein into inverted hexagonal (H(II)) mesophase modeled by molecular dynamics.

    PubMed

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

    2014-05-22

    The study investigates the unit cell structure of inverted hexagonal (H(II)) mesophase composed of monoolein (1-monoolein, GMO) and water using atomistic molecular dynamics methods without imposing any restraints on lipid and water molecules. Statistically meaningful and very contrast images of the radial mass density distribution, scrutinizing also the separate components water, monoolein, the polar headgroups of the lipids, the double bond, and the termini of the hydrocarbon chain (the tail), are obtained. The lipid/water interface structure is analyzed based on the obtained water density distribution, on the estimated number of hydrogen bonds per monoolein headgroup, and on the headgroup-water radial distribution functions. The headgroup mass density distribution demonstrates hexagonal shape of the monoolein/water interface that is well-defined at higher water/monoolein ratios. Water interacts with the headgroups by forming a three-layer diffusive mass density distribution, and each layer's shape is close to hexagonal, which is an indication of long-range structural interactions. It is found that the monoolein headgroups form a constant number of hydrogen bonds leaving an excessive amount of water molecules outside the first lipid coordination sphere. Furthermore, the quantity of water at the monoolein/water interface increases steadily upon extension of the unit cell, so the interface should have a very dynamic structure. Investigation of the hydrocarbon residues reveals high compression and well-expressed structuring of the tails. The tails form a very compressed and constrained structure of defined layers across the unit cell with properties corresponding to a more densely packed nonpolar liquid (oil). Due to the hexagonal shape the 2D packing frustration is constant and does not depend on the water content. All reported structural features are based on averaging of the atomic coordinates over the time-length of the simulation trajectories. That kind of

  5. 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

  6. Surface patch binding and mesophase separation in biopolymeric polyelectrolyte-polyampholyte solutions.

    PubMed

    Pathak, Jyotsana; Rawat, Kamla; Bohidar, H B

    2014-02-01

    Surface patch binding (SPB) induced mesophase separation causing complex coacervation between biopolymers: gelatin A-gelatin B, chitosan-gelatin A, chitosan-gelatin B, and, agar-gelatin B was investigated with and without salt (I=0-0.3 M NaCl). SPB was induced by pH change and three characteristic pHs identified transitions in a turbidity plot: intermolecular interactions ensued at pHc, coacervation transition occurred at pHΦ and phase separation was noticed at pHprep. Associative interactions lead to formation of soluble complexes at pHc exclusively through SPB whereas the coacervation transition was driven by electrostatic binding (EB). Neither pHc nor pHΦ displayed discernible ionic strength (till 50 mM) or temperature dependence, but coacervate yield reduced with increase in ionic strength. Coacervation was completely suppressed beyond 50 mM NaCl. Linear combination of attractive and repulsive parts operating between a polyelectrolyte (charged rod) with a polyampholyte (dipole or point charge) was used to model the interaction potential as function of ionic strength. Relative strength of SPB vis a vis EB was used as SPB index to establish a linear relationship with zeta potential ratio of binding partners. Different phase diagrams could be constructed which clearly identified distinct interaction regimes encountered in solutions undergoing coacervation transition. PMID:24161686

  7. 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. PMID:24685272

  8. Mesophase and size manipulation of itraconazole liquid crystalline nanoparticles produced via quasi nanoemulsion precipitation.

    PubMed

    Mugheirbi, Naila A; Tajber, Lidia

    2015-10-01

    The fabrication of drug nanoparticles (NPs) with process-mediated tunable properties and performances continues to grow rapidly during the last decades. This study investigates the synthesis and phase tuning of nanoparticulate itraconazole (ITR) mesophases using quasi nanoemulsion precipitation from acetone/water systems to seek out an alternative pathway to the nucleation-based NP formation. ITR liquid crystalline (LC) phases were formed and nematic-smectic mesomorphism was achieved via controlling solvent:antisolvent temperature difference (ΔTS:AS). The use of ΔTS:AS=49.5°C was associated with a nematic assembly, while intercalated smectic A layering was observed at ΔTS:AS=0°C, with both phases confined in the nanospheres at room temperature. The quasi emulsion system has not been investigated at the nanoscale to date and in contrary to the microscale, quasi nanoemulsion was observed over the solvent:antisolvent viscosity ratios of 1:7-1:1.4. Poly(acrylic acid) in the solvent phase exhibited a concentration dependent interaction when ITR formed NPs. This nanodroplet-based approach enabled the preparation of a stable ITR nanodispersion using Poloxamer 407 at 80°C, which was unachievable before using precipitation via nucleation. Findings of this work lay groundwork in terms of rationalised molecular assembly as a tool in designing pharmaceutical LC NPs with tailored properties.

  9. Structure of Escherichia coli OmpF porin from lipidic mesophase.

    PubMed

    Efremov, Rouslan G; Sazanov, Leonid A

    2012-06-01

    Outer membrane protein F, a major component of the Escherichia coli outer membrane, was crystallized for the first time in lipidic mesophase of monoolein in novel space groups, P1 and H32. Due to ease of its purification and crystallization OmpF can be used as a benchmark protein for establishing membrane protein crystallization in meso, as a "membrane lyzozyme". The packing of porin trimers in the crystals of space group H32 is similar to natural outer membranes, providing the first high-resolution insight into the close to native packing of OmpF. Surprisingly, interaction between trimers is mediated exclusively by lipids, without direct protein-protein contacts. Multiple ordered lipids are observed and many of them occupy identical positions independently of the space group, identifying preferential interaction sites of lipid acyl chains. Presence of ordered aliphatic chains close to a positively charged area on the porin surface suggests a position for a lipopolysaccharide binding site on the surface of the major E. coli porins.

  10. Too hot to handle? Synchrotron X-ray damage of lipid membranes and mesophases.

    PubMed

    Cherezov, Vadim; Riedl, Ken M; Caffrey, Martin

    2002-11-01

    The call for brighter synchrotron X-radiation sources for use in structural biology research is barely audible as we enter the new millennium. Our brightest sources are already creating havoc when used at design specifications because of radiation damage. The time is long overdue to take stock of where we are and where we wish to go with regards to using existing sources and to designing new ones. The problem of radiation damage is particularly acute in studies involving kinetics and mechanisms where cryo-techniques are not always viable. Accordingly, we need to understand the very nature of radiation damage and to devise means of minimizing it. This is the thrust of the current report as applied to lipid membranes and mesophases. The experiments were performed at the most brilliant beamlines at CHESS, the APS and the ESRF. Two very different types of radiation damage are reported here. One involves a dramatic phase transformation and the other a disordering of lamellar stacking. How beam energy and dose rate affect damage is also discussed. The work highlights the free-radical-mediated nature of the damage process and the need for additional studies if the most efficient use is to be made of an important resource, synchrotron radiation.

  11. Surfactant removal and silica condensation during the photochemical calcination of thin film silica mesophases.

    PubMed

    Dattelbaum, Andrew M; Amweg, Meri L; Ruiz, Julia D; Ecke, Laurel E; Shreve, Andrew P; Parikh, Atul N

    2005-08-01

    The evolution of photochemical surfactant removal and silica condensation from organically templated thin film silica nanocomposites with mesoscopic ordering has been probed using a combined application of Fourier transform infrared (FT-IR) spectroscopy and single wavelength ellipsometry. Thin films of silica nanocomposites were prepared by a previously reported evaporation-induced self-assembly process. Specifically, oxidized silicon and gold substrates were withdrawn at 25 mm/min from a subcritical micelle concentration solution containing an ethylene oxide surfactant as a structure-directing agent and tetraethyl orthosilicate as a silica precursor. Real-time grazing incidence difference FT-IR spectra of the nanocomposite films on gold taken during exposure to short-wavelength ultraviolet light (184-257 nm) show that surfactant removal and silica condensation occur gradually and concomitantly. Surfactant removal and silica reconstructions were found to be nearly complete after 90 min of exposure. Further, a transient feature was observed in the FT-IR spectra around 1713 cm(-1) during the UV exposure process and was assigned to a carbonyl (C=O) stretching mode absorption, reflecting the transient formation of a partially oxidized surfactant intermediate. From these data we propose a stepwise model for surfactant removal from the nanocomposite films. Ellipsometrically determined index of refraction values collected as a function of UV exposure are also shown to support such a stepwise mechanism of surfactant removal from the ordered nanocomposite silica thin film mesophases studied here. PMID:16852834

  12. 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.

  13. Molecular dynamics approach to water structure of H(II) mesophase of monoolein.

    PubMed

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

    2012-02-21

    The goal of the present work is to study theoretically the structure of water inside the water cylinder of the inverse hexagonal mesophase (H(II)) 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.

  14. Ferrielectricity in smectic-C^{*} dechiralization-line lattices.

    PubMed

    Mettout, B; Logbo, H Pasco; Gagou, Y; Vasseur, H; Gisse, P

    2016-04-01

    Recent experiments probing a new ferroelectric liquid crystal (CLF08) confined in cells with planar alignment have shown dielectric and optic anomalies suggesting the onset of ferrielectric ordering within the surface lattice of dechiralization lines. We present a phenomenological theory describing the corresponding phase transition sequence SmA→SmC^{*}→Ferri. Phase diagrams and thermodynamic, dielectric, and optic properties are worked out and compared with experiments. The anomalies are related to the predicted tristability of the experimental cells under applied electric field. The order parameters of Landau theory are reinterpreted in terms of line positions, allowing description of the entrance and exit line behavior, and yielding the prediction and identification of new limit phases within a nonconventional Landau approach. PMID:27176363

  15. Ferrielectricity in smectic-C^{*} dechiralization-line lattices.

    PubMed

    Mettout, B; Logbo, H Pasco; Gagou, Y; Vasseur, H; Gisse, P

    2016-04-01

    Recent experiments probing a new ferroelectric liquid crystal (CLF08) confined in cells with planar alignment have shown dielectric and optic anomalies suggesting the onset of ferrielectric ordering within the surface lattice of dechiralization lines. We present a phenomenological theory describing the corresponding phase transition sequence SmA→SmC^{*}→Ferri. Phase diagrams and thermodynamic, dielectric, and optic properties are worked out and compared with experiments. The anomalies are related to the predicted tristability of the experimental cells under applied electric field. The order parameters of Landau theory are reinterpreted in terms of line positions, allowing description of the entrance and exit line behavior, and yielding the prediction and identification of new limit phases within a nonconventional Landau approach.

  16. Ferrielectricity in smectic-C* dechiralization-line lattices

    NASA Astrophysics Data System (ADS)

    Mettout, B.; Logbo, H. Pasco; Gagou, Y.; Vasseur, H.; Gisse, P.

    2016-04-01

    Recent experiments probing a new ferroelectric liquid crystal (CLF08) confined in cells with planar alignment have shown dielectric and optic anomalies suggesting the onset of ferrielectric ordering within the surface lattice of dechiralization lines. We present a phenomenological theory describing the corresponding phase transition sequence Sm A →Sm C*→Ferri . Phase diagrams and thermodynamic, dielectric, and optic properties are worked out and compared with experiments. The anomalies are related to the predicted tristability of the experimental cells under applied electric field. The order parameters of Landau theory are reinterpreted in terms of line positions, allowing description of the entrance and exit line behavior, and yielding the prediction and identification of new limit phases within a nonconventional Landau approach.

  17. Phase states and thermomorphologic, thermotropic, and magnetomorphologic properties of lyotropic mesophases: Sodium lauryl sulphate-water-1-decanol liquid-crystalline system

    NASA Astrophysics Data System (ADS)

    Özden, Pınar; Nesrullajev, Arif; Oktik, Şener

    2010-12-01

    Phase states in sodium lauryl sulphate-water-1-decanol lyotropic liquid-crystalline system have been investigated for different temperature ranges. The dependence of triangle phase diagram types, phase boundaries, and sequence of lyotropic mesophases vs temperature has been found. The thermomorphologic, thermotropic, and magnetomorphologic properties of hexagonal E, lamellar D, nematic-calamitic NC , nematic-discotic ND , and biaxial nematic Nbx mesophases have been studied in detail. Dynamics of transformations of magnetically induced textures has been investigated. Peculiarities of typical and magnetically induced textures have been investigated in detail. Triangle phase diagrams of sodium lauryl sulphate-water-1-decanol lyotropic liquid-crystalline system for different temperatures and typical and magnetically induced textures of E, D, NC , ND , and Nbx mesophases are presented.

  18. John H. Dillon Medal Lecture: Magnetic Field Directed Self-Assembly of Block Copolymers and Surfactant Mesophases

    NASA Astrophysics Data System (ADS)

    Osuji, Chinedum

    2015-03-01

    Molecular self-assembly of block copolymers and small molecule surfactants gives rise to a rich phase behavior as a function of temperature, composition, and other variables. We consider the directed self-assembly of such soft mesophases using magnetic fields, principally through the use of in situ x-ray scattering studies. Field alignment is predicated on a sufficiently large product of magnetic anisotropy and grain size to produce magnetostatic interactions which are substantive relative to thermal forces. We examine the role of field strength on the phase behavior and alignment dynamics of a series of soft mesophases, outlining the possibility to readily create highly ordered functional materials over macroscopic length scales. We show that magnetic fields as large as 10 T have little discernable impact on the stability of block copolymer systems considered, with shifts in order-disorder transition temperatures of roughly 5 mK or smaller. Consequently, directed self-assembly in these systems proceeds by nucleation of randomly aligned grains which thereafter rotate into registry with the field. We highlight the tradeoff between decreasing mobility and increasing anisotropic field interaction that dictates alignment kinetics while transiting from a high temperature disordered state to an ordered system at lower temperatures. NSF support through DMR-0847534 is gratefully acknowledged.

  19. Chemical sensing of metal ions using a silica-micelle mesophase doubly functionalized by a fluorogenic ionophore and a masking agent.

    PubMed

    Suto, Yasuo; Uchida, Tatsuya; Kumata, Hidetoshi; Tsuzuki, Mikio; Fujiwara, Kitao

    2011-01-01

    We report on a chemical-sensing method based on the silica-micelle mesophase wherein both a fluoroionophore and a masking agent are embedded. Using this method, a highly selective detection of metal ions in an aqueous solution has been successfully demonstrated. Furthermore, simultaneous analyses of multisamples using a sensor array composed of functionalized mesoporous thin films were demonstrated for the first time.

  20. 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

  1. Highly Segregated Lamello-Columnar Mesophase Organizations and Fast Charge Carrier Mobility in New Discotic Donor-Acceptor Triads.

    PubMed

    Zhao, Ke-Qing; An, Ling-Ling; Zhang, Xiao-Bo; Yu, Wen-Hao; Hu, Ping; Wang, Bi-Qin; Xu, Jing; Zeng, Qing-Dao; Monobe, Hirosato; Shimizu, Yo; Heinrich, Benoît; Donnio, Bertrand

    2015-07-13

    Four new donor-acceptor triads (D-A-D) based on discotic and arylene mesogens have been synthesized by using Sonogashira coupling and cyclization reactions. This family of triads consists of two side-on pending triphenylene mesogens, acting as the electron-donating groups (D), laterally connected through short lipophilic spacers to a central perylenediimide (PI), benzo[ghi]perylenediimide (BI), or coronenediimide (CI) molecular unit, respectively, playing the role of the electron acceptor (A). All D-A-D triads self-organize to form a lamello-columnar oblique mesophase, with a highly segregated donor-acceptor (D-A) heterojunction organization, consequent to efficient molecular self-sorting. The structure consists in the regular alternation of two disrupted rows of triphenylene columns and a continuous row of diimine species. High-resolution STM images demonstrate that PI-TP2 forms stable 2D self-assembly nanostructures with some various degrees of regularity, whereas the other triads do not self-organize into ordered architectures. The electron-transport mobility of CI-TP2, measured by time-of-flight at 200 °C in the mesophase, is one order of magnitude higher than the hole mobility. By means of this specific molecular designing idea, we realized and demonstrated for the first time the so-called p-n heterojunction at the molecular level in which the electron-rich triphenylene columns act as the hole transient pathways, and the coronenediimide stacks form the electron-transport channels. PMID:26095600

  2. Lyotropic mesophases formed by solutions of sodium strearate in glycerol and water

    NASA Astrophysics Data System (ADS)

    Wang, Qingbing; Joshi, Leela; Satyendra Kumar, Satyendra; Yaravoy, Yury; Teanoosh, Moaddel

    2004-03-01

    Solutions of sodium stearate in concentrations ranging from 1 to 20 wt %, in glycerol and glycerol + water exhibit two phases between room temperature and 100 °C for all mixtures. In the high temperature phase, the solutions flow easily while they form a gel phase with unique elastic properties in the low temperature phase. Small angle neutron and x-ray scattering measurements performed on partially deutrated samples reveal structural details of these solutions. The high temperature phase is found to be an isotropic dispersion of micellar aggregates, the lower temperature phase possesses more complex structure. These results augmented with results from differential scanning calorimetry, NMR proton relaxation and other techniques will be presented. Supported by Unilever Research, USA.

  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. Light sensitive achiral polar polymeric composites

    NASA Astrophysics Data System (ADS)

    González-Henríquez, C. M.; Soto-Bustamante, E. A.; Vergara-Toloza, R. O.; Haase, W.

    2011-07-01

    The occurrence of antiferroelectric phenomenon in achiral composites composed of azo-benzene containing liquid crystals was observed. Some of the composites evidenced typical antiferroelectric polarization hysteresis loop in the mesophase, showing bilayer smectic C 2 mesophases with some interdigitation grade at the layer interface in a broad temperature range. Surprisingly composites of similar structure developed pyroelectricity but not switchable states. This new class of antiferroelectric materials is also capable of producing E-Z photoisomerization making them good candidates for energy harvesting.

  5. 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.

  6. Exploring the in meso crystallization mechanism by characterizing the lipid mesophase microenvironment during the growth of single transmembrane α-helical peptide crystals.

    PubMed

    van 't Hag, Leonie; Knoblich, Konstantin; Seabrook, Shane A; Kirby, Nigel M; Mudie, Stephen T; Lau, Deborah; Li, Xu; Gras, Sally L; Mulet, Xavier; Call, Matthew E; Call, Melissa J; Drummond, Calum J; Conn, Charlotte E

    2016-07-28

    The proposed mechanism for in meso crystallization of transmembrane proteins suggests that a protein or peptide is initially uniformly dispersed in the lipid self-assembly cubic phase but that crystals grow from a local lamellar phase, which acts as a conduit between the crystal and the bulk cubic phase. However, there is very limited experimental evidence for this theory. We have developed protocols to investigate the lipid mesophase microenvironment during crystal growth using standard procedures readily available in crystallography laboratories. This technique was used to characterize the microenvironment during crystal growth of the DAP12-TM peptide using synchrotron small angle X-ray scattering (SAXS) with a micro-sized X-ray beam. Crystal growth was found to occur from the gyroid cubic mesophase. For one in four crystals, a highly oriented local lamellar phase was observed, providing supporting evidence for the proposed mechanism for in meso crystallization. A new observation of this study was that we can differentiate diffraction peaks from crystals grown in meso, from peaks originating from the surrounding lipid matrix, potentially opening up the possibility of high-throughput SAXS analysis of in meso grown crystals.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.

  7. Exploring the in meso crystallization mechanism by characterizing the lipid mesophase microenvironment during the growth of single transmembrane α-helical peptide crystals.

    PubMed

    van 't Hag, Leonie; Knoblich, Konstantin; Seabrook, Shane A; Kirby, Nigel M; Mudie, Stephen T; Lau, Deborah; Li, Xu; Gras, Sally L; Mulet, Xavier; Call, Matthew E; Call, Melissa J; Drummond, Calum J; Conn, Charlotte E

    2016-07-28

    The proposed mechanism for in meso crystallization of transmembrane proteins suggests that a protein or peptide is initially uniformly dispersed in the lipid self-assembly cubic phase but that crystals grow from a local lamellar phase, which acts as a conduit between the crystal and the bulk cubic phase. However, there is very limited experimental evidence for this theory. We have developed protocols to investigate the lipid mesophase microenvironment during crystal growth using standard procedures readily available in crystallography laboratories. This technique was used to characterize the microenvironment during crystal growth of the DAP12-TM peptide using synchrotron small angle X-ray scattering (SAXS) with a micro-sized X-ray beam. Crystal growth was found to occur from the gyroid cubic mesophase. For one in four crystals, a highly oriented local lamellar phase was observed, providing supporting evidence for the proposed mechanism for in meso crystallization. A new observation of this study was that we can differentiate diffraction peaks from crystals grown in meso, from peaks originating from the surrounding lipid matrix, potentially opening up the possibility of high-throughput SAXS analysis of in meso grown crystals.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'. PMID:27298442

  8. 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.

  9. Thermotropic ionic liquid crystals. II. 1H and 23Na NMR study of the smectic mesophase of molten sodium n-butyrate and sodium isovalerate

    NASA Astrophysics Data System (ADS)

    Bonekamp, J. E.; Eguchi, T.; Plesko, S.; Jonas, J.

    1983-08-01

    The 1H and 23Na NMR studies of smectic ionic mesophases of molten sodium n-butyrate and sodium isovalerate are reported over the temperature range of the stability of the liquid crystalline phases. The 1H spin-lattice relaxation times T1 at ν0=9.2, 24.3, and 60 MHz for the anions of both the systems are interpreted in terms of diffusion intermolecular relaxation mechanism. The predicted anion diffusion coefficients are in agreement with those measured directly by spin-echo technique and indicate that the anion diffuses rapidly. In contrast to the T1 relaxation mechanism the results obtained for the proton relaxation times in the rotating coordinate frame T1ρ indicate that the order-fluctuation relaxation mechanism determines the frequency dispersion of T1ρ. The analysis of the T1ρ data provides an approximate measure of the order parameter S as a function of temperature. Fourier transform spectra of the 23Na transitions show that the electric field gradient (EFG) at the Na+ ion is nonaveraged and of such a strength as to produce a second order quadrupole effect in the spectra of the central transition. From the first-order splitting, the quadrupole coupling constant (QCC) is obtained as a function of temperature. The gradual temperature change of QCC demonstrates that only a single liquid crystalline phase exists over the temperature interval of the stability of the smectic mesophase. Using approximate analysis the correlation time τc for the EFG fluctuation is obtained from the 23Na T1 data for the melts of both sodium n-butyrate and sodium isovalerate.

  10. Investigation into liquid crystalline smectic-C* subphase stability using chiral and achiral dopants

    SciTech Connect

    Kirchhoff, J.; Hirst, L. S.

    2007-11-15

    In this paper we investigate the influence of chiral and achiral dopants on a chiral smectic liquid crystal material, which exhibits a rich phase sequence, including the antiferroelectric phase and the three-layer intermediate smectic (SmC*{sub FI1}) phase. Using polarized optical microscopy, differential scanning calorimetry, and x-ray diffraction we find that small amounts of achiral dopant have the ability to significantly broaden the SmC*{sub FI1} phase, whereas an oppositely-handed dopant (otherwise identical to the host material) destabilizes the phase. This work clearly indicates that bulk chirality strongly influences SmC*{sub FI1} phase formation and that steric effects also play an important role. Interestingly, addition of the shorter achiral molecule (8CB) was observed to increase the smectic layer spacing, most likely by suppressing interdigitation of alkyl chains between adjacent smectic layers. Control of the SmC*{sub FI1} phase width using mixtures in this way is clearly important for effective phase characterization, and could potentially lead to commercially viable materials with a stable SmC*{sub FI1} phase over a large temperature range.

  11. Effect of enantiomeric excess on the smectic-C* phases under electric field

    NASA Astrophysics Data System (ADS)

    Chemingui, M.; Soltani, T.; Marcerou, J. P.; Othman, T.

    2016-03-01

    A series of enantiomeric mixtures of 4-(1-methylheptyloxycarbonyl) phenol 4'-octyloxybiphenyl-4-carbonate (MHPOBC) is reported to understand the structures and stability conditions of emerging liquid crystal phases. The mesomorphic properties are studied by microscopic observation, electro-optic and dielectric measurements. The electric field-concentration (E-x) phase diagram for each phase at constant temperature is constructed. The complete electric field-temperature (E-T) phase diagrams for several enantiomeric mixtures of the antiferroelectric MHPOBC are established. These phase diagrams show the influence of optical purity on the phase stability and the unwinding threshold.

  12. Investigation into liquid crystalline smectic-C* subphase stability using chiral and achiral dopants.

    PubMed

    Kirchhoff, J; Hirst, L S

    2007-11-01

    In this paper we investigate the influence of chiral and achiral dopants on a chiral smectic liquid crystal material, which exhibits a rich phase sequence, including the antiferroelectric phase and the three-layer intermediate smectic (SmC*FI1) phase. Using polarized optical microscopy, differential scanning calorimetry, and x-ray diffraction we find that small amounts of achiral dopant have the ability to significantly broaden the SmC*FI1 phase, whereas an oppositely-handed dopant (otherwise identical to the host material) destabilizes the phase. This work clearly indicates that bulk chirality strongly influences SmC*FI1 phase formation and that steric effects also play an important role. Interestingly, addition of the shorter achiral molecule (8CB) was observed to increase the smectic layer spacing, most likely by suppressing interdigitation of alkyl chains between adjacent smectic layers. Control of the SmC*FI1 phase width using mixtures in this way is clearly important for effective phase characterization, and could potentially lead to commercially viable materials with a stable SmC*FI1 phase over a large temperature range.

  13. Effect of Pyridine on the Mesophase of Teraryl Liquid Crystals: A New Series of Nematic Liquid Crystals Named 2-(4-Alkoxybiphen-4'-yl)-5-methylpyridines.

    PubMed

    Chia, Win-Long; Huang, Yu-Sin

    2016-03-07

    A new series of teraryl 2-(4-alkoxybiphen-4'-yl)-5-methylpyridines (nO-PPPyMe, n = 3-8) nematic liquid crystal compounds, bearing a biphenylene core and a picoline terminus, were synthesized using a short two-step reaction, and overall yields between 34% and 38% were obtained. Spectral analysis results were in accordance with the expected structures. The thermotropic behavior of the teraryl liquid crystal compounds was investigated through polarized optical microscopy and differential scanning calorimetry. All compounds exhibited a solely enantiotropic nematic phase at the medium-high temperature range of 162.4-234.2 °C. Furthermore, the results for the nO-PPPyMe series were analyzed relative to three other compound series, mO-PPPyCN (m = 2-8), iO-PPQMe (i = 3-8) and xO-PPyPMe (x = 1-10). Consequently, the effect of pyridine on the mesophase of teraryl liquid crystals was demonstrated.

  14. Effect of Pyridine on the Mesophase of Teraryl Liquid Crystals: A New Series of Nematic Liquid Crystals Named 2-(4-Alkoxybiphen-4′-yl)-5-methylpyridines

    PubMed Central

    Chia, Win-Long; Huang, Yu-Sin

    2016-01-01

    A new series of teraryl 2-(4-alkoxybiphen-4′-yl)-5-methylpyridines (nO-PPPyMe, n = 3–8) nematic liquid crystal compounds, bearing a biphenylene core and a picoline terminus, were synthesized using a short two-step reaction, and overall yields between 34% and 38% were obtained. Spectral analysis results were in accordance with the expected structures. The thermotropic behavior of the teraryl liquid crystal compounds was investigated through polarized optical microscopy and differential scanning calorimetry. All compounds exhibited a solely enantiotropic nematic phase at the medium–high temperature range of 162.4–234.2 °C. Furthermore, the results for the nO-PPPyMe series were analyzed relative to three other compound series, mO-PPPyCN (m = 2–8), iO-PPQMe (i = 3–8) and xO-PPyPMe (x = 1–10). Consequently, the effect of pyridine on the mesophase of teraryl liquid crystals was demonstrated. PMID:26959017

  15. Structural effects of insulin-loading into HII mesophases monitored by electron paramagnetic resonance (EPR), small angle X-ray spectroscopy (SAXS), and attenuated total reflection Fourier transform spectroscopy (ATR-FTIR).

    PubMed

    Mishraki, Tehila; Ottaviani, Maria Francesca; Shames, Alexander I; Aserin, Abraham; Garti, Nissim

    2011-06-30

    Insulin entrapment within a monoolein-based reverse hexagonal (H(II)) mesophase was investigated under temperature-dependent conditions at acidic (pH 3) and basic (pH 8) conditions. Studying the structure of the host H(II) system and the interactions of insulin under temperature-dependent conditions has great impact on the enhancement of its thermal stabilization and controlled release for the purposes of transdermal delivery. Small angle X-ray spectroscopy (SAXS) measurements show that pH variation and/or insulin entrapment preserve the hexagonal structure and do not influence the lattice parameter. Attenuated total reflection Fourier transform spectroscopy (ATR-FTIR) spectra indicate that, although insulin interacts with hydroxyl groups of GMO in the interface region, it is not affected by pH variations. Hence different microenvironments within the H(II) mesophase were monitored by a computer-aided electron paramagnetic resonance (EPR) analysis using 5-doxylstearic acid (5-DSA) as a pH-dependent probe. The microviscosity, micropolarity, order of systems, and distribution of the probes in different microenvironments were influenced by three factors: temperature, pH, and insulin solubilization. When the temperature is increased, microviscosity and order parameters decreased at both pH 3 and 8, presenting different decrease trends. It was found that, at pH 3, the protein perturbs the lipid structure while "pushing aside" the un-ionized 5-DSA probe to fit into the narrow water cylinders. At the interface region (pH 8), the probe was distributed in two differently structured environments that significantly modifies by increasing temperature. Insulin loading within the H(II) mesophase decreased the order and microviscosity of both the microenvironments and increased their micropolarity. Finally, the EPR analysis also provides information about the unfolding/denaturation of insulin within the channel at high temperatures.

  16. 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.

  17. Frustration between syn- and anticlinicity in mixtures of chiral and non-chiral tilted smectic-C-type liquid crystals.

    PubMed

    Lagerwall, J P F; Heppke, G; Giesselmann, F

    2005-09-01

    We study the effects of mixing ferroelectric and antiferroelectric liquid-crystal compounds (FLCs and AFLCs) when the former are strictly synclinic and the latter strictly anticlinic, i.e. one mixture component exhibits only SmC* and the other only SmC(a)* as tilted phase. Three different paths between syn- and anticlinicity were detected: transition directly between SmC* and SmC(a)*, transition via the SmC(beta)* and SmC(gamma)* subphases, or by "escaping" the clinicity frustration by reducing the tilt to zero, i.e. the SmA* phase is extended downwards in temperature, separating SmC* from SmC(a)* in the phase diagram. The most common path is the one via the subphases, demonstrating that these phases appear as a result of frustration between syn- and anticlinic and, consequently, between syn- and antipolar order. For assessing the role of chirality, we also replaced the FLC with non-chiral synclinics. With one of the AFLCs, the route via supbhases was detected even in this case, suggesting that chirality--although necessary--does not have quite the importance that has previously been attributed to the appearance of the subphases. The path chosen in the mixture study seemed to be determined mainly by the synclinic component, the subphase induction occurring only when the SmA*-SmC* transition was second order.

  18. Revealing Mercury

    NASA Astrophysics Data System (ADS)

    Prockter, L. M.; Solomon, S. C.; Head, J. W.; Watters, T. R.; Murchie, S. L.; Robinson, M. S.; Chapman, C. R.; McNutt, R. L.

    2009-04-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, developed under NASA's Discovery Program, launched in August 2004. En route to insertion into orbit about Mercury in 2011, MESSENGER flies by Mercury three times. The first and second of these encounters were accomplished in January and October of 2008. These flybys viewed portions of Mercury's surface that were not observed by Mariner 10 during its reconnaissance of somewhat less than half of the planet in 1974-1975. All MESSENGER instruments operated during each flyby and returned a wealth of new data. Many of the new observations were focused on the planet's geology, including monochrome imaging at resolutions as high as 100 m/pixel, multispectral imaging in 11 filters at resolutions as high as 500 m/pixel, laser altimetry tracks extending over several thousands of kilometers, and high-resolution spectral measurements of several types of terrain. Here we present an overview of the first inferences on the global geology of Mercury from the MESSENGER observations. Whereas evidence for volcanism was equivocal from Mariner 10 data, the new MESSENGER images and altimetry provide compelling evidence that volcanism was widespread and protracted on Mercury. Color imaging reveals three common spectral units on the surface: a higher-reflectance, relatively red material occurring as a distinct class of smooth plains, typically with distinct embayment relationships interpreted to indicate volcanic emplacement; a lower-reflectance, relatively blue material typically excavated by impact craters and therefore inferred to be more common at depth; and a spectrally intermediate terrain that constitutes much of the uppermost crust. Three more minor spectral units are also seen: fresh crater ejecta, reddish material associated with rimless depressions interpreted to be volcanic centers, and high-reflectance deposits seen in some crater floors. Preliminary measurements of crater size

  19. Ferroelectric liquid-crystalline compounds containing a sulfinyl group as unique source of chirality: Asymmetric synthesis and mesomorphic properties

    SciTech Connect

    Cherkaoui, M.Z.; Nicoud, J.F.; Guillon, D.

    1994-11-01

    The synthesis and mesomorphism of a series of new ferroelectric liquid crystals containing a sulfinyl group as the unique chiral center are described. This chiral center was introduced in the optically active form into the mesogenic molecules via the asymmetric synthesis of sulfinamide, sulfoxide, and sulfinate functional groups, directly connected to the aromatic rigid core. The role of the sulfinyl group nature, of the aromatic rigid core structure, of the chiral center position and of the alkyl chain length on the liquid-crystalline behavior have been investigated systematically. A central rigid core are not in favor of the occurrence of the mesomorphic character. On the contrary, sulfinates at the end of the core give a smectic C phase, stable within a reasonable temperature range. On the other hand, the only change of the sulfinyl group has large effects on the thermal stability of the mesophases, on the transition temperatures and more deeply on the polymorphic nature. This change leads to thermal instability with the sulfoxide compounds and with some sulfinamide ones, whereas the sulfinate mesogens are perfectly stable from both optical and thermal points of view. Thermal smectic C and A phases have been systematically studied as a function of aliphatic chain lengths. The alkyl chain of the sulfinate group plays a predominant role. Smectic A phases are favored when this chain is short, whereas smectic C phases are favored for long chains. The thermal stability of the smectic C mesophase is strongly correlated to the tilt angle of the molecules inside the smectic layers. 25 refs., 23 figs., 14 tabs.

  20. Mesomorphic properties of chiral three-arm liquid crystals containing 1,2,4-butanetriol as core

    NASA Astrophysics Data System (ADS)

    Tian, Mei; Wu, Shuang-jie; Tian, Xiao-Wei; Yao, Dan-Shu; Li, Chong-Liang; Hu, Jian-She; Zhang, Bao-Yan

    2016-03-01

    A series of symmetric and asymmetric three-arm liquid crystals (TALCs) of which the molecular structure with a central core of 1, 2, 4-butanetriol attached by three rod-like mesogenic moieties have successfully been synthesized. The rod-like mesogenic side arms are 4‧-(4-(trifluoromethyl) benzoyloxy) biphenyl-4-carboxylic acid (TFBA) and 4‧-(4-(allyloxy) benzoyloxy) biphenyl-4-carboxylic acid (AOBA), respectively. BTA0 and BTA3 are symmetric TALCs with three TFBA or three AOBA as LC side arms, respectively. BTA1 is an asymmetric TALC with one AOBA and two TFBA as side arms. BTA2 is an asymmetric TALC with two AOBA and one TFBA as side arms. The chemical structures and LC properties of the LC side arms and TALCs were characterised by FTIR, 1H NMR, elemental analysis, DSC, TG, POM and X-ray diffractometer. TFBA displayed smectic B (SmB) phase, AOBA exhibited nematic (N) phase. The TALCs all displayed chiral mesophase properties. BTA0 displayed chiral smectic C (SmC∗) mesophase. BTA1, BTA2 and BTA3 exhibited cholesteric (ch) mesophase. In addition, a chiral smectic A (SmA∗) mesophase was observed for BTA1. The results indicated that the 1, 2, 4-butanetriol is vital in inducing chiral mesophase of the TALCs. The side arms also played an important role in the mesophase type and mesogenic region. The TALCs displayed cholesteric mesophase when nematic LC side arm AOBA was introduced into the chiral core. The mesogenic region of the TALCs increased with the content of the wide-mesophase-region LC side arm AOBA introduced into the TALCs increasing. The melting temperature and the clear temperature of the TALCs were lower than those of the LC side arms (TFBA and AOBA). The mesophase regions of the TALCs were wider than those of the LC side arms.

  1. 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.

  2. 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.

  3. 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.

  4. 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. PMID:26896840

  5. 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.

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

    PubMed

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

    2012-01-01

    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.

  7. 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

  8. How Are Preferences Revealed?

    PubMed

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

    2008-08-01

    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

  9. 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

  10. Interlayer interactions and the dependence of biaxiality of the chiral smectic-C* phase on electric field in the helical unwinding process.

    PubMed

    Song, Jang-Kun; Vij, J K; Kobayashi, Ichiro

    2007-05-01

    We investigate the unwinding process of pure and racemized mixtures of (1-methylheptyloxycarbonyl)phenyl- 4'-carboctyloxy-biphenyl-4-carboxylate (MHPOOCBC) in homeotropic cells by studying (i) the optical texture under crossed polarizers and (ii) the tilted conoscopy as a function of the electric field for different temperatures. The tilted conoscopy yields biaxiality and the tilt angle for values of the latter up to 45 degrees . We find that the unwinding process depends on the optical purity of the sample and the temperature. A cell with pure MHPOOCBC surprisingly exhibits a large positive biaxiality in the initial stages of the unwinding process. The magnitude of the positive biaxiality decreases with a decrease in the enantiomeric excess (EE) of the compound and eventually it becomes negative for a material having a low EE value. The negative biaxiality observed in a mixture with a low EE value is normal and can be explained by a double sine-Gordon equation proposed by Meyer. Microscopic observations show that the special unwinding behavior (positive biaxiality) is related to the helical fractures, that is, to the existence of discretely coiled helical structures. We show that these helical fractures arise from the existence of a narrow energy well in the synclinic position. This implies that the elastic constant near the synclinic position is significantly larger than in other positions. By adopting a semiempirical equation for the interlayer interactions which replaces the conventional equation, we successfully simulate the various unwinding behaviors. We reasonably conclude that the special interlayer interaction is due to the steric interactions between the two adjacent surfaces formed by somewhat tilted terminal parts of the molecules.

  11. [Sweet syndrome revealing leukemia].

    PubMed

    Elleuch, E; Hammami, B; Smaoui, F; Maaloul, I; Turki, H; Elloumi, M; Ben Jemaa, M

    2011-09-01

    Sweet syndrome is a neutrophilic dermatosis that can lead to various inflammatory and neoplastic pathologies. We report a case of Sweet syndrome revealing acute leukemia at a 13-year-old girl, who had no history of illness. The diagnosis was made in spite of atypical skin lesions and was confirmed by the skin biopsy and the bone marrow examination. In spite of corticosteroid therapy and chemotherapy, the patient died. Sweet syndrome's diagnosis requires an exhaustive etiologic survey. If there is no evidence of underlying disease, patients must be regularly monitored.

  12. 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.

  13. 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.

  14. The Climate Revealed

    NASA Astrophysics Data System (ADS)

    Burroughs, William

    1999-10-01

    El Niño, La Niña, global warming--terms that crop up frequently in current media coverage of anomalous weather conditions: a spring thaw in January in New York City...a snowstorm in Bakersfield, California...winterlike temperatures in Miami. Such phenomena as these and reports of devastating droughts, floods, and storms around the world bring home the fact of how deeply climate affects our daily lives--and of our inability to control the consequences of climatic events. Extraordinarily timely, The Climate Revealed explores the human-climate "relationship" in all its fascinating complexity. Packed with 250 beautiful, full-color photographs, the volume travels the globe to provide a detailed portrait of individual climate zones from the polar icecaps to the fiercest deserts. The expert and highly accessible text uncovers the essential elements--earth, air, fire and water--that make up the world's various climates. William Burroughs reveals the dramatic discoveries and techniques of historians and archaeologists in their search to understand climates of the past. In the book's conclusion he considers the future and presents every facet of the current environmental debate. With its detailed coverage of the past, present, and future, this marvelous work is essential reading for all those who want to understand one of the most critical facets of life, climate. William Burroughs is a well known and successful science author who has written four books on the weather including Does the Weather Really Matter? (1997), Weather Cycles: Real or Imaginary (1992), and Watching the World's Weather (1991), all published by Cambridge University Press.

  15. Revealing cosmic rotation

    NASA Astrophysics Data System (ADS)

    Yadav, Amit P. S.; Shimon, Meir; Keating, Brian G.

    2012-10-01

    Cosmological Birefringence, a rotation of the polarization plane of radiation coming to us from distant astrophysical sources, may reveal parity violation in either the electromagnetic or gravitational sectors of the fundamental interactions in nature. Until only recently this phenomenon could be probed with only radio observations or observations at UV wavelengths. Recently, there is a substantial effort to constrain such nonstandard models using observations of the rotation of the polarization plane of cosmic microwave background (CMB) radiation. This can be done via measurements of the B-modes of the CMB or by measuring its TB and EB correlations which vanish in the standard model. In this paper we show that EB correlations-based estimator is the best for upcoming polarization experiments. The EB-based estimator surpasses other estimators because it has the smallest noise and of all the estimators is least affected by systematics. Current polarimeters are optimized for the detection of B-mode polarization from either primordial gravitational waves or by large-scale structures via gravitational lensing. In the paper we also study the optimization of CMB experiments for the detection of cosmological birefringence, in the presence of instrumental systematics, which by themselves are capable of producing EB correlations, potentially mimicking cosmological birefringence.

  16. 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

  17. 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

  18. "Janus" supermolecular liquid crystals--giant molecules with hemispherical architectures.

    PubMed

    Saez, Isabel M; Goodby, John W

    2003-10-17

    Liquid crystals represent a unique class of self-organising systems, which although found in many day-to-day practical material applications, such as displays, are also intimately entwined with living processes. They have the potential, just like living systems, to provide us with a unique vehicle for the development of self-ordering nano- and mesoscopic-engineered materials with specific functional properties. In this article we describe a new concept for the design of self-assembling functional liquid crystals as segmented or "Janus" liquid-crystalline supermolecular materials in the form of structures that contain two different types of mesogenic units, which favour different types of mesophase structure, grafted onto the same star-shaped scaffold to create supermolecules that contain different hemispheres. The materials exhibit chiral nematic and chiral smectic C phases.

  19. Novel ferroelectric liquid crystals consisting glassy liquid crystal as chiral dopants

    NASA Astrophysics Data System (ADS)

    Chen, Huang-Ming Philip; Tsai, Yun-Yen; Lin, Chi-Wen; Shieh, Han-Ping David

    2006-08-01

    A series of ferroelectric liquid crystals consisting new glassy liquid crystals (GLCs) as chiral dopants were prepared and evaluated for their potentials in fast switching ability less than 1 ms. The properties of pure ferroelectric glassy liquid crystals (FGLCs) and mixtures were reported in this paper. In particular, the novel FGLC possessing wide chiral smectic C mesophase over 100 °C is able to suppress smectic A phase of host. The mixture containing 2.0 % GLC-1 performs greater alignment ability and higher contrast ratio than R2301 (Clariant, Japan) in a 2 μm pre-made cell (EHC, Japan). These results indicate that novel FLC mixtures consisting glassy liquid crystals present a promising liquid crystal materials for fast switching field sequential color displays.

  20. Synthesis and Thermotropic Studies of Two Novel Series of Kinked Liquid Crystals: 2-(4′-Alkoxybiphen-4-yl)-6-methylquinolines and 2-(6-Alkoxynaphthalen-2-yl)-6-methylquinolines

    PubMed Central

    Chia, Win-Long; Kuo, Ker-Non; Lin, Shao-Hsun

    2014-01-01

    Two novel homologous series of kinked (Z-shaped) liquid crystalline compounds were synthesized using a short two-step reaction. Yields of 30%–40% and 51%–57% were obtained for 2-(4′-alkoxybiphen-4-yl)-6-methylquinolines (nO-PPQMe, n = 3–8) and 2-(6-alkoxynaphthalen-2-yl)-6-methylquinolines (iO-NpQMe, i = 3–7), respectively. Spectral analyses agreed with the expected structures. The thermotropic behaviors of these compounds were investigated using polarized optical microscopy and differential scanning calorimetry. An enantiotropic nematic phase appeared to be the main mesophase in these two series of kinked liquid crystalline compounds, and an additional enantiotropic smectic C phase appeared when n = 8. PMID:24798752

  1. 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.

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

    PubMed

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

    2007-12-01

    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.

  3. Liquid-Crystalline Mesophases of Plasmid DNA in Bacteria

    NASA Astrophysics Data System (ADS)

    Reich, Ziv; Wachtel, Ellen J.; Minsky, Abraham

    1994-06-01

    Bacterial plasmids may often reach a copy number larger than 1000 per cell, corresponding to a total amount of DNA that may exceed the amount of DNA within the bacterial chromosome. This observation highlights the problem of cellular accommodation of large amounts of closed-circular nucleic acids, whose interwound conformation offers negligible DNA compaction. As determined by x-ray scattering experiments conducted on intact bacteria, supercoiled plasmids segregate within the cells into dense clusters characterized by a long-range order. In vitro studies performed at physiological DNA concentrations indicated that interwound DNA spontaneously forms liquid crystalline phases whose macroscopic structural properties are determined by the features of the molecular supercoiling. Because these features respond to cellular factors, DNA supercoiling may provide a sensitive regulatory link between cellular parameters and the packaging modes of interwound DNA in vivo.

  4. 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

  5. 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.

  6. Electrocardiograph abnormalities revealed during laparoscopy.

    PubMed

    Nijjer, Sukhjinder; Dubrey, Simon William

    2010-01-01

    This brief case presents a well patient in whom an electrocardiograph abnormality consistent with an accessory pathway was found during a routine procedure. We present the electrocardiographs, explain the underlying condition, and consider why the abnormality was revealed in this manner.

  7. X-ray study of mesomorphism of bent-core and chromonic mesogens

    NASA Astrophysics Data System (ADS)

    Joshi, Leela Pradhan

    The discovery of thermotropic biaxial nematic phase in bent-core mesogens, have engendered interest in these systems. Also, it undergoes optical switching about 100 times faster than conventional uniaxial nematic liquid crystal. Azo-substituted bent-core compounds, A131 and A103, were investigated as both offer an opportunity to observe their structures and phase transitions from the uniaxial nematic (Nu) to biaxial nematic (Nb) phase and from Nb to the underlying smectic-C (SmC) phase. Plank-like molecular systems are also expected to form Nb phase. Chromonic liquid crystals formed by aqueous solutions of plank-like dye molecules are interesting for their unique self-assembly and structural evolution. They have applications in optical element, coloring in food and textiles, and etc. Both systems were investigated with synchrotron x-ray scattering, polarizing optical microscopy, and differential scanning calorimetry. Temperature dependence of d-spacing and positional order correlations along the director clearly mark the phase boundaries where Nu-Nb transition was approximately 27° below the clearing point. Positional order correlation length of A131 increased from 1.5 in Nu to 3.3 molecular lengths in Nb phase, before it jumps by a factor of at least 5 in SmC phase. The lack of large discontinuous changes in the structural parameters and the subtle signatures in heat capacity establish the second order nature of Nu-Nb and Nb-SmC phase transitions. The chromonic system investigation results provide quantitative information of structural properties in nematic and columnar mesophases. We studied water solutions of (achiral) sunset yellow dye and (chiral and achiral) dihydrochloride salts of perylenebis-dicarboxydiimide. Positional order correlation lengths measurements, parallel and perpendicular to the aggregate axis, revealed that they increase with concentration and decrease with temperature. Temperature dependence of correlation lengths yielded the scission

  8. Generalized Langevin-Debye model of the field dependence of tilt, birefringence, and polarization current near the de Vries smectic-A* to smectic-C* liquid crystal phase transition.

    PubMed

    Shen, Yongqiang; Wang, Lixing; Shao, Renfan; Gong, Tao; Zhu, Chenhui; Yang, Hong; Maclennan, Joseph E; Walba, David M; Clark, Noel A

    2013-12-01

    In chiral smectic-A (Sm-A) liquid crystals, an applied electric field induces a tilt of the optic axis from the layer normal. When these materials are of the de Vries type, the electroclinic tilt susceptibility is unusually large, with the field-induced director reorientation accompanied by a substantial increase in optical birefringence with essentially no change in the smectic layer spacing. In order to account for the observed electro-optic behavior, we assume that the molecular orientation distribution in the Sm-A has two degrees of freedom: azimuthal orientation and tilt of the molecular long axis from the layer normal, with the tilt confined to a narrow range of angles. We present a generalized Langevin-Debye model of the response of this orientational distribution to applied field that gives a field-induced optic axis tilt, birefringence, and polarization dependence that agrees well with experimental measurements and reproduces the double-peaked polarization current response characteristic of a first-order Sm-A(*)-Sm-C(*) transition. Additionally, we find that the measured field-induced polarization and the Langevin-Debye model predictions can be quantitatively described as pre-transitional behavior near the tricritical point of a recently published generalized 3D XY model of interacting hard rods confined to reorient on a cone in the presence of an applied field.

  9. 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.

  10. 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.

  11. 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.

  12. [Abdominal cystic tumor revealing lymphangioleiomyomatosis].

    PubMed

    Barbier, L; Ebbo, M; Andrac-Meyer, L; Schneilitz, N; Le Treut, Y-P; Reynaud-Gaubert, M; Hardwigsen, J

    2009-02-01

    We report the case of a 39 year-old woman with many years of intermittent abdominal pain who was found to have cystic masses evocative of cystic lymphangioma involving the posterior mediastinal and retroperitoneum. Worsening abdominal pain led to a recommendation for laparoscopic unroofing and decompression of the cysts. During the postoperative period, hemorrhagic shock required reintervention with excision of the tumoral mass. Pathologic examination revealed lymphangioleiomyomatosis (LAM). On the 15th postoperative day, the patient developed a chylopneumothorax which required prolonged chest tube drainage. The presence of multiple polycystic lesions in the pulmonary parenchyma supported the diagnosis of diffuse LAM with primary extrapulmonary presentation. This diagnosis should be considered preoperatively since it modifies the treatment: a complete excision of the cystic lesions seems to be necessary in order to prevent bleeding and lymphatic extravasation.

  13. 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.

  14. 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

  15. 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.

  16. Focus groups reveal consumer ambivalence.

    PubMed

    1983-01-01

    According to qualitative research, Salvadoreans are ambivalent about the use of contraceptives. Since complete responsibility for management of the CSM project was accepted by the Association Demografica Salvadorena (ADS), the agency which operates the contraceptive social marketing project in El Salvador, in November 1980, the need for decisions in such areas as product price increases, introduction of new condom brands, promotion of the vaginal foaming tablet, and assessment of product sales performance had arisen. The ICSMP funded market research, completed during 1983, was intended to provide the data on which such decisions by ADS could be based. The qualitative research involved 8 focus groups, comprised of men and women, aged 18-45, contraceptive users and nonusers, from the middle and lower socioeconomic strata of the city of San Salvador and other suburban areas. In each group a moderator led discussion of family planning and probed respondents for specific attitudes, knowledge, and behavior regarding the use of contraceptives. To assess attitudes at a more emotional level, moderators asked respondents to "draw" their ideas on certain issues. A marked discrepancy was revealed between respondents' intellectual responses to the issues raised in group discussion, as opposed to their feelings expressed in the drawings. Intellectually, participants responded very positively to family planning practice, but when they were asked to draw their perceptions, ambivalent feelings emerged. Drawings of both the user and the nonuser convey primarily negative aspects for either choice. The user is tense and moody toward her children; the nonuser loses her attractiveness and "dies." Figures also show drawings of some of the attitudes of single and married male participants. 1 drawing shows an incomplete and a complete circle, symbolizing a sterilized man (incomplete) and a nonsterilized man (complete). Another picture depicts a chained man who has lost his freedom

  17. [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.

  18. 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.

  19. Revealing advantage in a quantum network

    NASA Astrophysics Data System (ADS)

    Mukherjee, Kaushiki; Paul, Biswajit; Sarkar, Debasis

    2016-07-01

    The assumption of source independence was used to reveal nonlocal (apart from standard Bell-CHSH scenario) nature of correlations generated in entanglement swapping experiments. In this work, we have discussed the various utilities of this assumption to reveal nonlocality (via generation of nonbilocal correlations) and thereby exploiting quantumness under lesser requirements compared to some standard means of doing the same. We have also provided with a set of sufficient criteria, imposed on the states (produced by the sources) under which source independence can reveal nonbilocal nature of correlations in a quantum network.

  20. 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

  1. 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.

  2. Systemic lupus erythematous revealed by cytomegalovirus infection

    PubMed Central

    Amel, Rezgui; Monia, Karmani; Anis, Mzabi; Fatma, Ben Fredj; Chadia, Laouani

    2016-01-01

    Cytomegalovirus (CMV) infection have been described as exacerbing systemic lupus erythematous (SLE). The role of CMV in starting off SLE remains object of debate. We report a severe presentation of SLE revealed by CMV infection with hemophogocytic syndrome. A 22 old women without a history of systemic disease developed a cutaneous eruption with fever and myalgia persistant for 2 weeks. Laboratory studies revealed a CMV serology supporting acute CMV infection, with positive antinuclear antidody, anti ds DNA, elevated liver functions tests, pancytopenia. Further exams revealed an hemophagocytic syndrome and a lupus nephritis. While receiving antiviral and corticosteroid therapy, the patient developed seizures related to a cerebral vasculitis. The outcome was favorable when intravenous immunoglobulins were associated. This observation showed that CMV infection in patients with SLE is often serious and difficult to diagnose and to treat, especially when SLE is not yet recognized. So we suggest all patients with recent SLE have routine testing for CMV immunity. PMID:27800096

  3. 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…

  4. The cattle genome reveals its secrets

    PubMed Central

    Burt, David W

    2009-01-01

    The domesticated cow is the latest farm animal to have its genome sequenced and deciphered. The members of the Bovine Genome Consortium have published a series of papers on the assembly and what the sequence reveals so far about the biology of this ruminant and the consequences of its domestication. PMID:19439025

  5. 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…

  6. 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...

  7. Nucleolar organization as revealed in cell spreads.

    PubMed

    Ghosh, S; Paweletz, N

    1996-07-01

    The nucleolar organization has been studied in spreads of cells either untreated or treated with hypotonic salt solution for different periods. A network corresponding to the nucleolonema becomes evident with progressive hypotonic treatment. The network reveals units comparable to the rDNA transcriptional units in length and is associated with tufts of fibrils and granules. Spread preparations from cycloheximide treated cells reveal a thread-like axis and often 'Christmas tree'-like configurations within these units. Spacers joining the units can also be detected. It is supposed that the transcriptional units move outwards with their transcriptional products where the processing takes place. In loose nucleoli, this network forms the nucleolonema, which remains associated with the granules, the processed transcriptional products. In compact nucleoli the network is obliterated by the granules and they form the major component of the nucleoli. Such organization represents all the events in the transcription and processing of ribosomal RNA.

  8. 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.

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

    PubMed

    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.

  10. What Eye Movements Reveal about Deaf Readers

    PubMed Central

    Bélanger, Nathalie N.; Rayner, Keith

    2014-01-01

    Levels of illiteracy in the deaf populations around the world have been extremely high for decades and much higher than the illiteracy levels found in the general population. Research has mostly focused on deaf readers’ difficulties rather than on their strengths, which can then inform reading education. Deaf readers are a unique population. They process language and the world surrounding them mostly via the visual channel and this greatly affects how they read or might learn to read. The study of eye movements in reading provides highly sophisticated information about how words and sentences are processed and our research with deaf readers reveals the importance of their uniqueness. PMID:26594098

  11. 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

  12. Changes in Pluto's Atmosphere Revealed by Occultations

    NASA Astrophysics Data System (ADS)

    Sicardy, Bruno; Widemann, Thomas; Lellouch, Emmanuel; Veillet, Christian; Colas, Francois; Roques, Francoise; Beisker, Wolfgang; Kretlow, Mike; Cuillandre, Jean-Charles; Hainaut, Olivier

    After the discovery and study of Pluto's tenuous atmosphere in 1985 and 1988 with stellar occultations 14 years were necessary before two other occultations by the planet could be observed on 20 July 2002 and 21 August 2002 from Northern Chile with a portable telescope and from CFHT in Hawaii respectively. These occultations reveal drastric changes in Pluto's nitrogen atmosphere whose pressure increased by a factor two or more since 1988. In spite of an increasing distance to the Sun (and a correlated decrease of solar energy input at Pluto) this increase can be explained by the fact that Pluto's south pole went from permanent darkness to permanent illumination between 1988 and 2002. This might cause the sublimation of the south polar cap and the increase of pressure which could go on till 2015 according to current nitrogen cycle models. Furthermore we detect temperature contrasts between the polar and the equatorial regions probed on Pluto possibly caused by different diurnally averaged insolations at those locations. Finally spikes observed in the light curves reveal a dynamical activity in Pluto's atmosphere.

  13. 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.

  14. Mammalian phylogeny reveals recent diversification rate shifts.

    PubMed

    Stadler, Tanja

    2011-04-12

    Phylogenetic trees of present-day species allow investigation of the rate of evolution that led to the present-day diversity. A recent analysis of the mammalian phylogeny challenged the view of explosive mammalian evolution after the Cretaceous-Tertiary (K/T) boundary (65 Mya). However, due to lack of appropriate methods, the diversification (speciation minus extinction) rates in the more recent past of mammalian evolution could not be determined. In this paper, I provide a method that reveals that the tempo of mammalian evolution did not change until ∼ 33 Mya. This constant period was followed by a peak of diversification rates between 33 and 30 Mya. Thereafter, diversification rates remained high and constant until 8.55 Mya. Diversification rates declined significantly at 8.55 and 3.35 Mya. Investigation of mammalian subgroups (marsupials, placentals, and the six largest placental subgroups) reveals that the diversification rate peak at 33-30 Mya is mainly driven by rodents, cetartiodactyla, and marsupials. The recent diversification rate decrease is significant for all analyzed subgroups but eulipotyphla, cetartiodactyla, and primates. My likelihood approach is not limited to mammalian evolution. It provides a robust framework to infer diversification rate changes and mass extinction events in phylogenies, reconstructed from, e.g., present-day species or virus data. In particular, the method is very robust toward noise and uncertainty in the phylogeny and can account for incomplete taxon sampling. PMID:21444816

  15. The effects of molecular and lattice structures on thermotropic phase behaviour of zinc(II) undecanoate and isomeric zinc(II) undecynoates

    NASA Astrophysics Data System (ADS)

    Nelson, Peter N.; Taylor, Richard A.; Ellis, Henry A.

    2013-02-01

    Molecular structures, hydrocarbon chain packing, in the crystal lattice and their effects on the thermal behaviour of saturated and isomeric zinc(II) undecynoates have been investigated by a variety of physical methods. All the compounds crystallize in a monoclinic crystal system with a being the long axis. The hydrocarbon chains adopt the fully extended all-trans conformation and are arranged as methyl-methyl overlapping bilayers within a lamellar. Furthermore, in order to enhance lattice stability, hydrocarbon chains, from different layers in the lamellar are not in the same plane but are packed in an alternating spatial arrangement and are tilted at ca. 60° to the metal basal plane. In a molecule, four carbonyl groups bind to a zinc atom, in a bridging bidentate mode, to form a three dimensional polymeric network. At elevated temperatures a highly viscous phase, a polymeric ionic mesophase, possibly a smectic C phase, is observed for 10-undecynoate only, whereas two crystal-crystal and crystal-isotropic liquid transitions are observed for the undecanoate and 9-undecynoate, respectively. Though head group coordination is nearly iso-structural, differences in molecular symmetry and lattice packing are evident. These arise from differences in the spatial orientation of the high electron density hydrocarbon chains in the crystal lattice. Indeed, it is the relative balance between head group electrostatic and van der Waals interactions at elevated temperatures that accounts for formation of the mesophase. Surprisingly, all the freshly synthesized compounds are meta-stable, only achieving complete stability over several days. Furthermore, on heating and cooling the compounds, thermotropic behaviour is altered so that on re-heating, subtle changes in phase textures are observed.

  16. [Pneumothorax revealed by postoperative computed tomography].

    PubMed

    Ikeda, Shizuka; Katori, Kiyoshi; Fujimoto, Minoru; Nitahara, Keiichi; Higa, Kazuo

    2005-11-01

    We report a case of pneumothorax revealed by postoperative computed tomography. A 39-year-old obese woman (height 153 cm, weight 70 kg) with fractures of the radius, ulna, clavicle, and femur in a traffic accident, was scheduled for osteosynthesis. Anesthesia was induced with thiopental and maintained with 50% nitrous oxide in oxygen and sevoflurane. The Spo2 decreased from 99% to 94% during the surgery. Bilateral chest sounds were symmetrical. The Spo2 increased to 100% after discontinuation of nitrous oxide. Pneumothorax was not evident on a postoperative chest X-ray, but computed tomography of the chest demonstrated right-sided pneumothorax. An ECG electrode had overlapped the fractured rib on the preoperative chest X-ray.

  17. 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.

  18. Protein Vivisection Reveals Elusive Intermediates in Folding

    SciTech Connect

    Zheng, Zhongzhou; Sosnick, Tobin R.

    2010-05-25

    Although most folding intermediates escape detection, their characterization is crucial to the elucidation of folding mechanisms. Here, we outline a powerful strategy to populate partially unfolded intermediates: A buried aliphatic residue is substituted with a charged residue (e.g., Leu {yields} Glu{sup -}) to destabilize and unfold a specific region of the protein. We applied this strategy to ubiquitin, reversibly trapping a folding intermediate in which the {beta}5-strand is unfolded. The intermediate refolds to a native-like structure upon charge neutralization under mildly acidic conditions. Characterization of the trapped intermediate using NMR and hydrogen exchange methods identifies a second folding intermediate and reveals the order and free energies of the two major folding events on the native side of the rate-limiting step. This general strategy may be combined with other methods and have broad applications in the study of protein folding and other reactions that require trapping of high-energy states.

  19. Protein vivisection reveals elusive intermediates in folding.

    PubMed

    Zheng, Zhongzhou; Sosnick, Tobin R

    2010-04-01

    Although most folding intermediates escape detection, their characterization is crucial to the elucidation of folding mechanisms. Here, we outline a powerful strategy to populate partially unfolded intermediates: A buried aliphatic residue is substituted with a charged residue (e.g., Leu-->Glu(-)) to destabilize and unfold a specific region of the protein. We applied this strategy to ubiquitin, reversibly trapping a folding intermediate in which the beta5-strand is unfolded. The intermediate refolds to a native-like structure upon charge neutralization under mildly acidic conditions. Characterization of the trapped intermediate using NMR and hydrogen exchange methods identifies a second folding intermediate and reveals the order and free energies of the two major folding events on the native side of the rate-limiting step. This general strategy may be combined with other methods and have broad applications in the study of protein folding and other reactions that require trapping of high-energy states.

  20. Can Clustering in Genotype Space Reveal "Niches"?

    PubMed

    D'Andrea, Rafael; Ostling, Annette

    2016-01-01

    Community ecology lacks the success enjoyed by population genetics to quantify the relative roles played by deterministic and stochastic processes. It has been proposed that clustered patterns of abundance in genotype space provide evidence of selection in microbial communities, since no such clustering would arise in the absence of selection. We critique this test for its unrealistic null hypothesis. We show mathematically and with simulations that point mutations alone lead to clustering in genotype space by causing correlations between abundances of similar genotypes. We also show potential deviations from the mutation-only pattern caused by immigration from a source pool. Clustered patterns in genotype space may still be revealing of selection if analyzed quantitatively but only if neutral and selective regimes can be distinguished once mutation and immigration are included in the null model.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Stable ferroelectric liquid crystals derived from salicylaldimine-core.

    PubMed

    Veerabhadraswamy, Bhyranalyar N; Rao, D S Shankar; Yelamaggad, Channabasaveshwar V

    2015-03-26

    Five pairs of enantiomers derived from salicylaldimine-core have been prepared by condensing (R)- or (S)-4-(octan-2-yloxy)anilines with 4-formyl-3-hydroxyphenyl 4-(n-alkoxy)benzoates. They have been designed to probe the correlation between molecular structure and mesomorphism, and especially to provide stable mesogens having potential for applications in ferroelectric liquid crystal devices. Thus, they have been substituted with a chiral tail at one end and by n-alkoxy chains of varying length at the other terminal. A detailed study confirms an indistinguishable behavior of all ten mesogens exhibiting an enantiotropic chiral smectic C (SmC*) phase besides blue phase (BP) and chiral nematic (N*) phase. The SmC* phase occurring over a 50-70 °C thermal width shows ferroelectric switching with spontaneous polarization (Ps) value crossing over 100 nC/cm(2). Circular dichroism spectroscopic study of the mesophases confirms the chromophores of the molecules being in the macroscopic chiral (helical) environment.

  7. 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

  8. Revealing the Hot Side of Epsilon Aurigae

    NASA Astrophysics Data System (ADS)

    Hoard, Donald; Stencel, Robert; Howell, Steve

    2012-12-01

    We request a small investment of 24 minutes of Spitzer time, to obtain four IRAC observations of epsilon Aurigae. A naked eye object located near Capella, epsilon Aurigae is the eclipsing binary star with the longest known orbital period, showing a single long duration (~2 yr) eclipse every 27.1 yr. For much of the last 200 years, the nature of the eclipsing object defied explanation. We recently demonstrated that epsilon Aurigae consists of a high luminosity F0 post-AGB star in orbit with a B5 V star surrounded by a solar system sized (~8 AU diameter) disk of cool, dust-dominated material. The eclipse of epsilon Aurigae is a rare event; moreover, it is a unique astrophysical opportunity, since the backlighting of the disk by the high luminosity eclipsed star reveals details that cannot be detected in similar dusty disks around single stars. The current eclipse started in August 2009 and ended in July 2011; we are now in the post-eclipse phase, when the irradiation-heated side of the disk will begin rotating into view. The goals for these observations include: (1) extend our ongoing IRAC monitoring campaign covering the current eclipse to post-eclipse visits; (2) provide a consistent, well-calibrated space-based set of IR photometry for comparison with ongoing ground-based work; and (3) use the composite results to constrain the thermal profile of the disk. A key expectation of these particular observations is to reveal the irradiation-heated portion of the disk, which will be visible on its trailing side following eclipse. Observations of this side of the disk will be crucial to test and constrain new models of disk structure. As part of our overall monitoring campaign with Spitzer, Hubble, Herschel, and numerous ground-based facilities, these proposed observations will make an important contribution to the understanding of stellar evolution in binary stars, including mass transfer and evolution studies, along with new insights into astrophysical disks and post

  9. Dynamic Environmental Photosynthetic Imaging Reveals Emergent Phenotypes.

    PubMed

    Cruz, Jeffrey A; Savage, Linda J; Zegarac, Robert; Hall, Christopher C; Satoh-Cruz, Mio; Davis, Geoffry A; Kovac, William Kent; Chen, Jin; Kramer, David M

    2016-06-22

    Understanding and improving the productivity and robustness of plant photosynthesis requires high-throughput phenotyping under environmental conditions that are relevant to the field. Here we demonstrate the dynamic environmental photosynthesis imager (DEPI), an experimental platform for integrated, continuous, and high-throughput measurements of photosynthetic parameters during plant growth under reproducible yet dynamic environmental conditions. Using parallel imagers obviates the need to move plants or sensors, reducing artifacts and allowing simultaneous measurement on large numbers of plants. As a result, DEPI can reveal phenotypes that are not evident under standard laboratory conditions but emerge under progressively more dynamic illumination. We show examples in mutants of Arabidopsis of such "emergent phenotypes" that are highly transient and heterogeneous, appearing in different leaves under different conditions and depending in complex ways on both environmental conditions and plant developmental age. These emergent phenotypes appear to be caused by a range of phenomena, suggesting that such previously unseen processes are critical for plant responses to dynamic environments. PMID:27336966

  10. 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.

  11. 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.

  12. 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.

  13. Revealing Invisible Photonic Inscriptions: Images from Strain.

    PubMed

    Ding, Tao; Cao, Guoshuai; Schäfer, Christian G; Zhao, Qibin; Gallei, Markus; Smoukov, Stoyan K; Baumberg, Jeremy J

    2015-06-24

    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

  14. 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. PMID:22261419

  15. 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

  16. 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

  17. Biosignatures as revealed by spectropolarimetry of Earthshine.

    PubMed

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

    2012-03-01

    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. PMID:22382980

  18. Integrative Analysis Reveals Regulatory Programs in Endometriosis.

    PubMed

    Yang, Huan; Kang, Kai; Cheng, Chao; Mamillapalli, Ramanaiah; Taylor, Hugh S

    2015-09-01

    Endometriosis is a common gynecological disease found in approximately 10% of reproductive-age women. Gene expression analysis has been performed to explore alterations in gene expression associated with endometriosis; however, the underlying transcription factors (TFs) governing such expression changes have not been investigated in a systematic way. In this study, we propose a method to integrate gene expression with TF binding data and protein-protein interactions to construct an integrated regulatory network (IRN) for endometriosis. The IRN has shown that the most regulated gene in endometriosis is RUNX1, which is targeted by 14 of 26 TFs also involved in endometriosis. Using 2 published cohorts, GSE7305 (Hover, n = 20) and GSE7307 (Roth, n = 36) from the Gene Expression Omnibus database, we identified a network of TFs, which bind to target genes that are differentially expressed in endometriosis. Enrichment analysis based on the hypergeometric distribution allowed us to predict the TFs involved in endometriosis (n = 40). This included known TFs such as androgen receptor (AR) and critical factors in the pathology of endometriosis, estrogen receptor α, and estrogen receptor β. We also identified several new ones from which we selected FOXA2 and TFAP2C, and their regulation was confirmed by quantitative real-time polymerase chain reaction and immunohistochemistry (IHC). Further, our analysis revealed that the function of AR and p53 in endometriosis is regulated by posttranscriptional changes and not by differential gene expression. Our integrative analysis provides new insights into the regulatory programs involved in endometriosis.

  19. Revealing the quantum regime in tunnelling plasmonics.

    PubMed

    Savage, Kevin J; Hawkeye, Matthew M; Esteban, Rubén; Borisov, Andrei G; Aizpurua, Javier; Baumberg, Jeremy J

    2012-11-22

    When two metal nanostructures are placed nanometres apart, their optically driven free electrons couple electrically across the gap. The resulting plasmons have enhanced optical fields of a specific colour tightly confined inside the gap. Many emerging nanophotonic technologies depend on the careful control of this plasmonic coupling, including optical nanoantennas for high-sensitivity chemical and biological sensors, nanoscale control of active devices, and improved photovoltaic devices. But for subnanometre gaps, coherent quantum tunnelling becomes possible and the system enters a regime of extreme non-locality in which previous classical treatments fail. Electron correlations across the gap that are driven by quantum tunnelling require a new description of non-local transport, which is crucial in nanoscale optoelectronics and single-molecule electronics. Here, by simultaneously measuring both the electrical and optical properties of two gold nanostructures with controllable subnanometre separation, we reveal the quantum regime of tunnelling plasmonics in unprecedented detail. All observed phenomena are in good agreement with recent quantum-based models of plasmonic systems, which eliminate the singularities predicted by classical theories. These findings imply that tunnelling establishes a quantum limit for plasmonic field confinement of about 10(-8)λ(3) for visible light (of wavelength λ). Our work thus prompts new theoretical and experimental investigations into quantum-domain plasmonic systems, and will affect the future of nanoplasmonic device engineering and nanoscale photochemistry.

  20. Anticipatory looks reveal expectations about discourse relations.

    PubMed

    Rohde, Hannah; Horton, William S

    2014-12-01

    Previous research provides evidence for expectation-driven processing within sentences at phonological, lexical, and syntactic levels of linguistic structure. Less well-established is whether comprehenders also anticipate pragmatic relationships between sentences. To address this, we evaluate a unit of discourse structure that comprehenders must infer to hold between sentences in order for a discourse to make sense-the intersentential coherence relation. In a novel eyetracking paradigm, we trained participants to associate particular spatial locations with particular coherence relations. Experiment 1 shows that the subset of listeners who successfully acquired the location∼relation mappings during training subsequently looked to these locations during testing in response to a coherence-signaling intersentential connective. Experiment 2 finds that listeners' looks during sentences containing coherence-biasing verbs reveal expectations about upcoming sentence types. This work extends existing research on prediction beyond sentence-internal structure and provides a new methodology for examining the cues that comprehenders use to establish relationships at the discourse level.

  1. 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. PMID:20875475

  2. 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

  3. 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. PMID:27586942

  4. A Liquid Crystalline Oligomer Exhibiting Nematic and Twist-Bend Nematic Mesophases.

    PubMed

    Mandle, Richard J; Goodby, John W

    2016-04-01

    The twist-bend nematic phase (NTB ) has been described as the structural link between the untilted uniaxial nematic phase (N) and the helical chiral nematic phase (N*). The NTB phase exhibits phenomena of fundamental importance to science, that is, 1) the spontaneous formation of a helical pitch on the nanometer scale in a fluid and 2) the spontaneous breaking of mirror symmetry, leading to the emergence of chiral domains in an achiral system. In this Communication, we present a study on T49 [bis(4-(9-(4-((4-cyanobenzoyl)oxy)phenyl)nonyl)phenyl) 4,4'-(nonane-1,9-diyl)dibenzoate], a liquid-crystalline oligomer exhibiting the twist-bend nematic phase, which has a molecular length that is of comparable dimensions to the sub-10 nm pitch determined for CB9CB, and provide new insights into the differentiation between the nano- and macro-science for self-assembling supermolecular systems.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  6. 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.

  7. 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.

  8. Some aspects of the orientational order distribution of flexible chains in a diblock mesophase

    SciTech Connect

    Lorthioir, Cédric Randriamahefa, Solo

    2013-12-14

    The segmental motions of flexible chains in the lamellar structure of a strongly segregated poly(styrene)-poly(dimethylsiloxane) (PS-PDMS) diblock were investigated over a time scale of a few tens of microseconds. {sup 2}H NMR experiments were performed on the PDMS block, selectively perdeuterated. Transverse relaxation measurements show that the main part of the PDMS repeat units display anisotropic reorientational motions within the diblock lamellae and such a segmental ordering essentially results from interchain steric repulsions. {sup 2}H double quantum-based experiments evidenced a non-uniform local stretching of PDMS chains and enabled the underlying distribution of the orientational order parameter to be determined quantitatively. Besides, a fraction of the PDMS chain segments, about 14%, were found to display isotropic – or nearly isotropic – reorientations, which could be assigned to repeat units located within a thin sublayer (about 1–2 nm) at the lamellae midplane, but also deeper in the lamellae, close to folded parts of the chains. These experimental results were confronted to theoretical descriptions of opposing polymer brushes and, in particular, to the strong-stretching theory (SST) including the entropic contribution of free chain ends.

  9. 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

  10. Interaction of some laser radiations with the lauric acid in mesophase

    NASA Astrophysics Data System (ADS)

    Dumitru, Mihaela A.; Honciuc, Maria; Popescu, Ion M.

    1994-07-01

    In `optoelectronic devices' area, a new domain occurred: organic and biological optoelectronics. Since 1988 our researches axed on this exciting theme and several works materialize the results we obtained. In this paper, we used the lauric acid, a fatty acid, which can be found, for example, under an esterified form, in the cocobutter.

  11. 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

  12. Antioxidant peptidomics reveals novel skin antioxidant system.

    PubMed

    Yang, Hailong; Wang, Xu; Liu, Xiuhong; Wu, Jing; Liu, Cunbao; Gong, Weiming; Zhao, Zhiqiang; Hong, Jing; Lin, Donghai; Wang, Yizheng; Lai, Ren

    2009-03-01

    It is generally agreed that reactive oxygen species (ROS) contribute to skin aging, skin disorders, and skin diseases. Skin possesses an extremely efficient antioxidant system. This antioxidant activity is conferred by two systems: antioxidant enzymes and small molecules that can scavenge ROS by donating electrons. No gene-encoded secreted ROS scavengers have been reported. Amphibian skin is a multifunctional organ acting in defense, respiration, and water regulation, although it seems susceptible. Amphibian skins are easily harmed by biological or non-biological attacks such as microorganism infection or radiation injury. Among vertebrates, skins of amphibian are exposed to more dangers of radiation injury than others. Radiation toxicity occurs by directly attacking the genetic material and/or by generating ROS. In addition, amphibian skin respiration and inflammatory response also induce ROS generation. It is rational to hypothesize that amphibian skins should have potent free radical scavenging and radioprotective ability for their survival. Rana pleuraden is distributed in Southwest of China; it lives in the subtropical plateau (altitude around 2300 m) where there is strong ultraviolet radiation and long duration of sunshine. By peptidomics and genomics approaches, a large amount of antioxidant peptides belonging to 11 different groups with variable structures were isolated from the skin secretions of R. pleuraden. Their free radical scavenging and anti-inflammatory abilities were studied. All of these peptide share highly homologous preproregions, although mature antioxidant peptides have very divergent primary structures, suggesting the possibility of a common ancestor. Some peptides were also found to have multifunctional properties, such as combined antioxidant, anti-inflammatory, and antimicrobial activities. According to our knowledge, no gene-encoded specific antioxidant peptides have been reported except metallothionein. Our work possibly reveals a new

  13. 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.

  14. Distinct cytoskeletal domains revealed in sperm cells

    PubMed Central

    1984-01-01

    Antibodies against different cytoskeletal proteins were used to study the cytoskeletal organization of human spermatozoa. A positive staining with actin antibodies was seen in both the acrosomal cap region and the principal piece region of the tail. However, no staining was obtained with nitrobenzoxadiazol-phallacidin, suggesting that most of the actin was in the nonpolymerized form. Most of the myosin immunoreactivity was confirmed to a narrow band in the neck region of spermatozoa. Tubulin was located to the entire tail, whereas vimentin was only seen in a discrete band-like structure encircling the sperm head, apparently coinciding with the equatorial segment region. Surface staining of the spermatozoa with fluorochrome-coupled Helix pomatia agglutinin revealed a similar band-like structure that co-distributed with the vimentin- specific staining. Instead, other lectin conjugates used labeled either the acrosomal cap region (peanut and soybean agglutinins), both the acrosomal cap and the postacrosomal region of the head (concanavalin A), or the whole sperm cell surface membrane (wheat germ and lens culinaris agglutinins and ricinus communis agglutinin l). In lectin blotting experiments, the Helix pomatia agglutinin-binding was assigned to a 80,000-mol-wt polypeptide which, together with vimentin, also resisted treatment with Triton X-100. Only the acrosomal cap and the principal piece of the tail were decorated with rabbit and hydridoma antibodies against an immunoanalogue of erythrocyte alpha-spectrin (p230). p230 appeared to be the major calmodulin-binding polypeptide in spermatozoa, as shown by a direct overlay assay of electrophoretic blots of spermatozoa with 125I-calmodulin. The results indicate that spermatozoa have a highly specialized cytoskeletal organization and that the distribution of actin, spectrin, and vimentin can be correlated with distinct surface specializations of the sperm cells. This suggest that cytoskeleton may regulate the maintenance

  15. 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.

  16. Private haplotypes can reveal local adaptation

    PubMed Central

    2014-01-01

    Background Genome-wide scans for regions that demonstrate deviating patterns of genetic variation have become common approaches for finding genes targeted by selection. Several genomic patterns have been utilized for this purpose, including deviations in haplotype homozygosity, frequency spectra and genetic differentiation between populations. Results We describe a novel approach based on the Maximum Frequency of Private Haplotypes – MFPH – to search for signals of recent population-specific selection. The MFPH statistic is straightforward to compute for phased SNP- and sequence-data. Using both simulated and empirical data, we show that MFPH can be a powerful statistic to detect recent population-specific selection, that it performs at the same level as other commonly used summary statistics (e.g. FST, iHS and XP-EHH), and that MFPH in some cases capture signals of selection that are missed by other statistics. For instance, in the Maasai, MFPH reveals a strong signal of selection in a region where other investigated statistics fail to pick up a clear signal that contains the genes DOCK3, MAPKAPK3 and CISH. This region has been suggested to affect height in many populations based on phenotype-genotype association studies. It has specifically been suggested to be targeted by selection in Pygmy groups, which are on the opposite end of the human height spectrum compared to the Maasai. Conclusions From the analysis of both simulated and publicly available empirical data, we show that MFPH represents a summary statistic that can provide further insight concerning population-specific adaptation. PMID:24885734

  17. 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

  18. Passive seismology reveals biannual calving periodicity

    NASA Astrophysics Data System (ADS)

    Bartholomaus, T. C.; Larsen, C. F.; West, M. E.; Oneel, S.

    2013-12-01

    Iceberg calving is a large and variable component of the total mass loss from marine-terminating glaciers worldwide. However, the processes that control the size and variability of calving fluxes are poorly understood. Even more basic descriptions of iceberg calving, such as its seasonality, are uncertain. Here, we present nearly two years of automatically-estimated calving fluxes at Yahtse Glacier, a tidewater glacier whose terminus flows at ~7 km/yr towards the Gulf of Alaska. At the terminus, ice losses to calving and submarine melt total approximately 1.5 km^3/yr. In order to identify temporal variability in this mean rate, we develop a statistical model of calving size based on characteristics of calving-generated icequakes. These characteristics include 4 amplitude-based variables and 5 variables related to the shape of the icequake envelope. We build our model by combining automatically-detected icequakes (O'Neel et al., 2007) located at the terminus of Yahtse Glacier (Jones et al., 2013) with a training set of 1400 icequakes produced by visually-observed calving events (Bartholomaus et al., 2012). In each of the models tested (regression trees, multinomial logistic regression and multiple linear regession), icequake duration emerges as the single best predictor of iceberg size, consistent with past studies (Qamar, 1988; O'Neel et al., 2007). Additional predictors, such as the mean icequake amplitude and the kurtosis of the icequake envelope improve the predictive capability of the model and reduce the mean squared error to well-within the error of the in-person classification. Once validated, we apply our model to ~ 400,000 icequakes produced by calving events at Yahtse Glacier between June 2009 and September 2011. These results reveal fluctuations in calving rate at a range of timescales, including twice per year. We suggest that the roughly 50%, biannual variation in calving rate is the result of the trade-off between two competing processes at the

  19. 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

  20. Shocking Detail of Superstar's Activity Revealed

    NASA Astrophysics Data System (ADS)

    1999-10-01

    NASA's Chandra X-ray Observatory has imaged Eta Carinae and revealed a hot inner core around this mysterious superstar. The new X-ray observation shows three distinct structures: an outer, horseshoe shaped ring about two light years in diameter, a hot inner core about 3 light months in diameter, and a hot central source less than a light month in diameter which may contain the superstar. All three structures are thought to represent shock waves produced by matter rushing away from the superstar at supersonic speeds. The temperature of the shock-heated gas ranges from 60 million degrees Celsius in the central regions to 3 million degrees Celsius on the outer structure. An earlier image of Eta Carinae by the Hubble Space Telescope revealed two spectacular bubbles of gas expanding in opposite directions away from a central bright region at speeds in excess of a million miles per hour. The inner region visible in the Chandra image has never been resolved before, and appears to be associated with a central disk of high velocity gas rushing out at much higher speeds perpendicular to the bipolar optical nebula. "It is not what I expected," said Dr. Fred Seward of the Harvard-Smithsonian Center for Astrophysics. "I expected to see a strong point source with a little diffuse emission cloud around it. Instead, we see just the opposite- a bright cloud of diffuse emission, and much less radiation from the center." "The Chandra image contains some puzzles for existing ideas of how a star can produce such hot and intense X-rays," agreed Prof. Kris Davidson of the University of Minnesota. "In the most popular theory, X-rays are made by colliding gas streams from two stars so close together that they'd look like a point source to us. But what happens to gas streams that escape to farther distances? The extended hot stuff in the middle of the new image gives demanding new conditions for any theory to meet." Eta Carinae is one of the most enigmatic and intriguing objects in our

  1. Chandra Data Reveal Rapidly Whirling Black Holes

    NASA Astrophysics Data System (ADS)

    2008-01-01

    A new study using results from NASA's Chandra X-ray Observatory provides one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly. The whirling of these giant black holes drives powerful jets that pump huge amounts of energy into their environment and affects galaxy growth. A team of scientists compared leading theories of jets produced by rotating supermassive black holes with Chandra data. A sampling of nine giant galaxies that exhibit large disturbances in their gaseous atmospheres showed that the central black holes in these galaxies must be spinning at near their maximum rates. People Who Read This Also Read... NASA’s Swift Satellite Catches First Supernova in The Act of Exploding Black Holes Have Simple Feeding Habits Jet Power and Black Hole Assortment Revealed in New Chandra Image Erratic Black Hole Regulates Itself "We think these monster black holes are spinning close to the limit set by Einstein's theory of relativity, which means that they can drag material around them at close to the speed of light," said Rodrigo Nemmen, a visiting graduate student at Penn State University, and lead author of a paper on the new results presented at American Astronomical Society in Austin, Texas. The research reinforces other, less direct methods previously used which have indicated that some stellar and supermassive black holes are spinning rapidly. According to Einstein's theory, a rapidly spinning black hole makes space itself rotate. This effect, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic, high-speed jet. Computer simulations by other authors have suggested that black holes may acquire their rapid spins when galaxies merge, and through the accretion of gas from their surroundings. "Extremely fast spin might be very common for large

  2. 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

  3. 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.

  4. 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

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

    PubMed

    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

  6. Stated and revealed inequality aversion in three subject pools

    PubMed Central

    Beranek, Benjamin; Cubitt, Robin; Gächter, Simon

    2016-01-01

    This paper reports data from three subject pools (n=717 subjects) using techniques based on those of Loewenstein, et al. (1989) and Blanco, et al. (2011) to obtain parameters, respectively, of stated and revealed inequality aversion. We provide a replication opportunity for those papers, with two innovations: (i) a design which allows stated and revealed preferences to be compared at the individual level; (ii) assessment of robustness of findings across subjects from a UK university, a Turkish university and Amazon Mechanical Turk. Our findings on stated aversion to inequality are qualitatively similar to those of Loewenstein, et al. in each of our subject pools, whereas there are notable differences between some of our findings on revealed preference and those of Blanco, et al. We find that revealed advantageous inequality aversion is often stronger than revealed dis-advantageous inequality aversion. In most subject pools, we find some (weak) correlation between corresponding parameters of stated and revealed inequality aversion. PMID:27069847

  7. Bent core liquid crystal elastomers

    SciTech Connect

    Verduzco, R.; DiMasi, E.; Luchette, P.; Ho Hong, S.; Harden, J.; Palffy-Muhoray, P.; Kilbey II, S.M.; Sprunt, S.; Gleeson, G.T. Jakli, A.

    2010-07-28

    Liquid crystal (LC) elastomers with bent-core side-groups incorporate the properties of bent-core liquid crystals in a flexible and self-supporting polymer network. Bent-core liquid crystal elastomers (BCEs) with uniform alignment were prepared by attaching a reactive bent-core LC to poly(hydrogenmethylsiloxane) and crosslinking with a divinyl crosslinker. Phase behavior studies indicate a nematic phase over a wide temperature range that approaches room temperature, and thermoelastic measurements show that these BCEs can reversibly change their length by more than a factor of two upon heating and cooling. Small-angle X-ray scattering studies reveal multiple, broad low-angle peaks consistent with short-range smectic C order of the bent-core side groups. A comparison of these patterns with predictions of a Landau model for short-range smectic C order shows that the length scale for smectic ordering in BCEs is similar to that seen in pure bent-core LCs. The combination of rubber elasticity and smectic ordering of the bent-core side groups suggests that BCEs may be promising materials for sensing, actuating, and other advanced applications.

  8. 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.

  9. 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 1.21 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL GENERAL ENFORCEMENT REGULATIONS General Labeling Requirements § 1.21 Failure to reveal material facts....

  10. 21 CFR 1.21 - Failure to reveal material facts.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Failure to reveal material facts. 1.21 Section 1.21 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL GENERAL ENFORCEMENT REGULATIONS General Labeling Requirements § 1.21 Failure to reveal material facts....

  11. 21 CFR 1.21 - Failure to reveal material facts.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Failure to reveal material facts. 1.21 Section 1.21 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL GENERAL ENFORCEMENT REGULATIONS General Labeling Requirements § 1.21 Failure to reveal material facts....

  12. How Costly is Hospital Quality? A Revealed-Preference Approach*

    PubMed Central

    Romley, John A.; Goldman, Dana P.

    2013-01-01

    We analyze the cost of quality improvement in hospitals, dealing with two challenges. Hospital quality is multidimensional and hard to measure, while unobserved productivity may influence quality supply. We infer the quality of hospitals in Los Angeles from patient choices. We then incorporate ‘revealed quality’ into a cost function, instrumenting with hospital demand. We find that revealed quality differentiates hospitals, but is not strongly correlated with clinical quality. Revealed quality is quite costly, and tends to increase with hospital productivity. Thus, non-clinical aspects of the hospital experience (perhaps including patient amenities) play important roles in hospital demand, competition, and costs. PMID:22299199

  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. [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. PMID:24709317

  15. 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

  16. 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

  17. Genome-Wide Scan Reveals Mutation Associated with Melanoma

    MedlinePlus

    ... 1999 Spotlight on Research 2012 July 2012 (historical) Genome-Wide Scan Reveals Mutation Associated with Melanoma A ... out to see if a technology called whole genome sequencing would help them find other genetic risk ...

  18. 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.

  19. 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.

  20. 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.

  1. External ear nodule revealing a disseminated Kaposi disease.

    PubMed

    Rachadi, Hanane; Zemmez, Youssef; Znati, Kaoutar; Ismaili, Nadia; Hassam, Badreddine

    2016-01-01

    Kaposi disease (KD) is an angiogenetic tumor process, characterized by its various clinical aspects. Its pathogenesis is multifactorial and it was attributed to HHV-8 infection. We report an original case of disseminated KD revealed by solitary lesion of external ear in a patient treated by corticosteroids for bullous pemphigoid. PMID:27617947

  2. 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.

  3. Nilaja Sun's "No Child"...: Revealing Teaching and Learning through Theater

    ERIC Educational Resources Information Center

    Hetland, Lois

    2009-01-01

    This article presents an analysis of Nilaja Sun's one-woman play, "No Child" . . ., that applies the Studio Habits of Mind framework to reveal essential features of great teaching artistry and great teaching. The play conveys much about twenty-first century schools and the policies that control them; about respect, equity, justice, and the lack of…

  4. [Two cases of cryptococcal meningitis revealed by an ischemic stroke].

    PubMed

    Kouame-Assouan, A E; Cowppli-Bony, P; Aka-Anghui Diarra, E; Assi, B; Doumbia, M; Diallo, L; Adjien, K C; Akani, E; Sonan, T; Diagana, M; Boa, Y E; Kouassi, B

    2007-02-01

    The usual clinical expression of neuromeningeal cryptococcosis is a meningoencephalitis. We report two cases of neurocryptococcosis which have been revealed by an unusual clinical aspect: an ischemic stroke with a vasculitis mechanism. The two patients had a positive reaction for the HIV and we discussed the responsibility of the HIV or the Cryptococcus in the occurrence of the cerebral infarct.

  5. 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 ...

  6. 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

  7. 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

  8. 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

  9. Hospital study reveals strategies for improving media relations.

    PubMed

    Fitzgerald, P E; Embrey-Wahl, L

    1987-01-01

    A nationwide study revealed that hospital administrators feel inadequate when dealing with the media, and also think the media does not understand the hospital business. Many strategies are available to counter these problems, including some that emphasize issues related to bed size. PMID:3583722

  10. 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.

  11. 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 Young Children". In all three…

  12. 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

  13. 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…

  14. Carbohydrate active enzymes revealed in Coptotermes formosanus transcriptome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A normalized cDNA library of Coptotermes formosanus was constructed using mixed RNA isolated from workers, soldiers, nymphs and alates of both sexes. Sequencing of this library generated 131,637 EST and 25,939 unigenes were assembled. Carbohydrate active enzymes (CAZymes) revealed in this library we...

  15. TSV reveal height and dimension metrology by the TSOM method

    NASA Astrophysics Data System (ADS)

    Vartanian, Victor; Attota, Ravikiran; Park, Haesung; Orji, George; Allen, Richard A.

    2013-04-01

    This paper reports on an investigation to determine whether through-focus scanning optical microscopy (TSOM) is applicable to micrometer-scale through-silicon via (TSV) reveal metrology. TSOM has shown promise as an alternative inspection and dimensional metrology technique for FinFETs and defects. In this paper TSOM measurements were simulated using 546 nm light and applied to copper TSV reveal pillars with height in the 3 μm to 5 μm range and diameter of 5 μm. Simulation results, combined with white light interferometric profilometry, are used in an attempt to correlate TSOM image features to variations in TSV height, diameter, and sidewall angle (SWA). Simulations illustrate the sensitivity of Differential TSOM Images (DTI's) using the metric of Optical Intensity Range (OIR), for 5 μm diameter and 5 μm height TSV Cu reveal structures, for variation of SWA (Δ = 2°, OIR = 2.35), height (Δ = 20 nm, OIR = 0.28), and diameter (Δ = 40 nm, OIR = 0.57), compared to an OIR noise floor of 0.01. In addition, white light interferometric profilometry reference data is obtained on multiple TSV reveal structures in adjacent die, and averages calculated for each die's SWA, height, and diameter. TSOM images are obtained on individual TSV's within each set, with DTI's obtained by comparing TSV's from adjacent die. The TSOM DTI's are compared to average profilometry data from identical die to determine whether there are correlations between DTI and profilometry data. However, with several significant TSV reveal features not accounted for in the simulation model, it is difficult to draw conclusions comparing profilometry measurements to TSOM DTI's when such features generate strong optical interactions. Thus, even for similar DTI images there are no discernible correlations to SWA, diameter, or height evident in the profilometry data. The use of a more controlled set of test structures may be advantageous in correlating TSOM to optical images.

  16. Systematic toxicological analysis revealing a rare case of captan ingestion.

    PubMed

    Gottzein, Anne K; Musshoff, Frank; Madea, Burkhard

    2013-07-01

    This article presents a case of suicide by intoxication with various pharmaceuticals, particularly anticonvulsants, combined with the fungicide captan. A cause of death could not be ascertained at autopsy. However, systematic toxicological analysis (STA) including a screening via solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) for (semi) volatile organic compounds revealed results suggesting a possible cause of death. The effects of captan on the human organism, its metabolism, and distribution will be discussed. Macroscopically, the cause of death was unascertained. STA revealed clonazepam, citalopram, and its metabolites, lamotrigine, levetiracetam, lacosamide, clonazepam, captan, and its metabolite tetrahydrophthalimide (THPI). For the first time, it was detected in human viscera. A quantification of THPI was performed to obtain distribution in the organs. The significance of a complete STA must be emphasized. The presence of THPI would have been missed without previous detection of captan. Consequently, this fatality would not have been investigated satisfactorily.

  17. 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.

  18. [Deep dorsal penile vein thrombosis revealing Behcet's disease].

    PubMed

    Beddouche, Ali; Ouaziz, Hicham; Zougaghi, Sinane; Alaoui, Abdelilah; Dergamoun, Hamza; El Sayegh, Hachem; Iken, Ali; Benslimane, Lounis; Nouini, Yassine

    2016-01-01

    Deep dorsal penile vein thrombosis (DDPVT)is a rare and little known urologic emergency. It requires an early etiological and symptomatic approach to preserve erectile function and prevent recurrences. This study reports a case of dorsal penile vein thrombosis revealed by spontaneous priapism that didn't resolve adequately and confirmed by penile Doppler ultrasound. After management of priapism and DDPVT, the etiological investigation revealed Behcet's disease whose diagnosis was based on the association of a major criteria, such as oral aphthous ulcers with 3 minor criteria such as: genital aphthous ulcers, ocular involvement, and a positive skin pathergy test within 24h. The patient underwent etiological treatment with good clinical evolution and preservation of erectile function. PMID:27583081

  19. Multisystem Langerhans Cell Histiocytosis in Adults Revealed by Skin Lesions.

    PubMed

    Atarguine, Hanane; Hocar, Ouafa; Oussmane, Samia; Mouafik, Sara Batoul; Hamdaoui, Abderrachid; Hafiane, Hanan; Belbaraka, Rhizlane; Akhdari, Nadia; Amal, Said

    2016-01-01

    A 37-year-old woman with no remarkable medical or family history presented with papules and vesicles on an erythematous background involving the neck, sacrum, and folds (postauricular, axillary, inguinal, and under the breasts) (Figure 1). During the previous year, she was treated with local and systemic antifungals without improvement. Her history included a secondary amenorrhea, polydipsia, and polyuria (6 L/d) that started 2 years prior. Physical examination revealed chronic bilateral purulent otorrhea with thick eardrums. Histologic examination of skin biopsy revealed a highly suggestive appearance of multisystem Langerhans cell histiocytosis (LCH) with immunohistochemistry (anti-PS100 and anti-CD1a), which were positive (Figure 2A and 2B). Pituitary magnetic resonance imaging showed a thickening of the pituitary stalk in relation to a location histiocytic (Figure 3). Bone gaps were objectified on two radiographic tibial diaphyseal. Results from computed tomography (CT) scan showed a magma coelio mesenteric, axillary, and inguinal lymph nodes. PMID:27319965

  20. Stable Chromosome Condensation Revealed by Chromosome Conformation Capture.

    PubMed

    Eagen, Kyle P; Hartl, Tom A; Kornberg, Roger D

    2015-11-01

    Chemical cross-linking and DNA sequencing have revealed regions of intra-chromosomal interaction, referred to as topologically associating domains (TADs), interspersed with regions of little or no interaction, in interphase nuclei. We find that TADs and the regions between them correspond with the bands and interbands of polytene chromosomes of Drosophila. We further establish the conservation of TADs between polytene and diploid cells of Drosophila. From direct measurements on light micrographs of polytene chromosomes, we then deduce the states of chromatin folding in the diploid cell nucleus. Two states of folding, fully extended fibers containing regulatory regions and promoters, and fibers condensed up to 10-fold containing coding regions of active genes, constitute the euchromatin of the nuclear interior. Chromatin fibers condensed up to 30-fold, containing coding regions of inactive genes, represent the heterochromatin of the nuclear periphery. A convergence of molecular analysis with direct observation thus reveals the architecture of interphase chromosomes. PMID:26544940

  1. Ascites and other incidental findings revealing undiagnosed systemic rheumatoid arthritis.

    PubMed

    Szeto, Matthew Chak Hin; Disney, Benjamin; Perkins, Philip; Wood, Gordon

    2015-06-08

    We describe a case of a 43-year-old man presenting to the gastroenterology outpatient department with exudative ascites. Mediastinal lymphadenopathy, pericardial effusion and pleural effusion were detected on further imaging. Further clinical examination revealed subcutaneous nodules on the left arm, which were confirmed to be rheumatoid nodules on histology. Inflammatory markers were elevated with positive serology for rheumatoid factor and anticyclic citrullinated protein antibody. Our investigations excluded tuberculosis, pancreatitis and malignancy in the patient. Following review by a rheumatologist, a diagnosis of systemic rheumatoid arthritis (RA) was made. Pleuritis and pericarditis are well recognised as extra-articular manifestation of RA. Ascites, however, is rarely recognised as a manifestation of RA. Our literature search revealed two other cases of ascites due to RA disease activity, and both patients had long-standing known RA. This case adds to the discussion on whether ascites and peritonitis should be classified as extra-articular manifestations of RA.

  2. 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.

  3. 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.

  4. Benign Cystic Peritoneal Mesothelioma Revealed by Small Bowel Obstruction.

    PubMed

    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.

  5. 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

  6. Intracranial hemorrhage revealing pseudohypoparathyroidism as a cause of fahr syndrome.

    PubMed

    Swami, Abhijit; Kar, Giridhari

    2011-01-01

    Pseudohypoparathyroidism is an infrequently encountered disease. It is one of the causes of Fahr syndrome which also is a rare clinical entity caused by multiple diseases. A 4-year-old man hospitalized for sudden onset left hemiparesis and hypertension was diagnosed to have right thalamic and midbrain hemorrhage on plain CT scan of the head which also revealed co-existent extensive intracranial calcifications involving the basal ganglia and cerebellum bilaterally. General physical examination revealed features of Albright hereditary osteodystrophy, goitre, hypertension, left hemiparesis, and signs of cerebellar dysfunction. Laboratory findings suggested hypocalcemia, hyperphosphatemia along with high TSH, low FT(4), low FT(3), and high anti-TPO antibody. Though bilateral intracranial calcifications are usually encountered as an incidental radiological finding in the CT scan of brain, in this case, the patient admitted for thalamic and midbrain hemorrhage was on investigation for associated intracranial calcification, and goitre was also found to have coexisting pseudohypoparathyroidism and autoimmune hypothyroidism.

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

    PubMed

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

    2014-11-01

    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.

  8. A circadian sleep disorder reveals a complex clock.

    PubMed

    Mignot, Emmanuel; Takahashi, Joseph S

    2007-01-12

    Circadian rhythms are established by transcription of clock genes and autoregulatory transcriptional feedback loops. In this issue, Xu et al. (2007) characterize mice expressing a human Per2 mutation identified in patients with familial advanced sleep phase syndrome. Their results reveal that PER2 phosphorylation, by CK1delta and other kinases, is surprisingly complex and has opposite effects on PER2 levels and period length. PMID:17218251

  9. A shoulder-hand syndrome revealing a lung cancer.

    PubMed

    Akasbi, N; Elidrissi, M; Tahiri, L; Shimi, M; Kadi, N; Elouazzani, F Z; Elmrini, A; Harzy, T

    2013-02-01

    Shoulder-hand syndrome is a reflex sympathetic dystrophy which is usually associated with minor trauma, fracture or surgical procedures on bones, or follows peripheral nerve injury. In the present report, we describe a patient who developed sympathetic dystrophy which revealed a lung cancer. Reflex sympathetic dystrophy, therefore, should be considered an occasional manifestation of a paraneoplastic syndrome warranting a thorough search for underlying malignancy.

  10. 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.

  11. 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.

  12. 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

    2016-02-01

    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.

  13. 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

  14. 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

    2016-01-01

    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

  15. Light scattering from thin smectic liquid crystal films

    SciTech Connect

    Spector, M.S.

    1993-01-01

    Quasi-elastic light scattering experiments have been performed on the tilted phases of thin smectic liquid crystal films. Films of only a few layers in thickness allow for study of phase transitions in a quasi-two-dimensional, substrate-free system. In the bend and splay geometries, it is found the scattering is well described by a simple elastic free energy describing in-plane fluctuations. The coupling of bond-orientation to the molecular tilt allows the investigation of bond-orientation order in the hexatic Smectite-I phase. This thesis discusses the elasticity and dynamics in terms of a defect-mediated theory of two-dimensional melting. In intermediate geometries, the dynamic signal reveals the presence of a previously unreported slow mode in the Smectite-C phase of 4-(2-methylbutyl)-phenyl-4[prime]-(octyloxy)-(1,1[prime])-biphenyl-4-carboxylate (8OSI). The wavevector dependence of the scattered intensity for the new mode is well described by the selection rules for out-of-plane fluctuations of the film. The overdamped dynamics reveal a non-hydrodynamic and extremely slow decay. In the Smectite-I phase of 8OSI, where the director fluctuations are strongly coupled to orientational fluctuations of the hexatic order, it is found textural defects develop in the director fields, destroying the magnetic alignment. Experiments were also performed on mixtures of 8OSI and 4-n-hexyl-phenyl-4-n-(decyloxy)-benzthiolate ([bar 1]4S6) liquid crystals. For mixtures with more than 50% [bar 1]4S6, no hexatic phase and melting proceeded via a first-order Smectic-C to Smectic-J transition. At lower concentrations of [bar 1]4S6, the author was able to change the critical properties of the Smectic-C to Smectic-I phase transition, by increasing the quantity of [bar 1]4S6 in the mixture. In the vicinity of the crystal-hexatic-liquid triple point, the Smectic-C to Smectic-I transition becomes first-order due to the influence of the crystal order-parameter.

  16. Influence of vitamin E acetate and other lipids on the phase behavior of mesophases based on unsaturated monoglycerides.

    PubMed

    Sagalowicz, L; Guillot, S; Acquistapace, S; Schmitt, B; Maurer, M; Yaghmur, A; de Campo, L; Rouvet, M; Leser, M; Glatter, O

    2013-07-01

    The phase behavior of the ternary unsaturated monoglycerides (UMG)-DL-α-tocopheryl acetate-water system has been studied. The effects of lipid composition in both bulk and dispersed lyotropic liquid crystalline phases and microemulsions were investigated. In excess water, progressive addition of DL-α-tocopheryl acetate to a binary UMG mixture results in the following phase sequence: reversed bicontinuous cubic phase, reversed hexagonal (H(II)) phase, and a reversed microemulsion. The action of DL-α-tocopheryl acetate is then compared to that of other lipids such as triolein, limonene, tetradecane, and DL-α-tocopherol. The impact of solubilizing these hydrophobic molecules on the UMG-water phase behavior shows some common features. However, the solubilization of certain molecules, like DL-α-tocopherol, leads to the presence of the reversed micellar cubic phase (space group number 227 and symmetry Fd3m) while the solubilization of others does not. These differences in phase behavior are discussed in terms of physical-chemical characteristics of the added lipid molecule and its interaction with UMG and water. From an applications point of view, phase behavior as a function of the solubilized content of guest molecules (lipid additive in our case) is crucial since macroscopic properties such as molecular release depend strongly on the phase present. The effect of two hydrophilic emulsifiers, used to stabilize the aqueous dispersions of UMG, was studied and compared. Those were Pluronic F127, which is the most commonly used stabilizer for these kinds of inverted type structures, and the partially hydrolyzed emulsifier lecithin (Emultop EP), which is a well accepted food-grade emulsifier. The phase behavior of particles stabilized by the partially hydrolyzed lecithin is similar to that of bulk sample at full hydration, but this emulsifier interacts significantly with the internal structure and affects it much more than F127. PMID:23705681

  17. 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.

  18. 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.

  19. Studies of nanocomposites of carbon nanotubes and a negative dielectric anisotropy liquid crystal.

    PubMed

    Kalakonda, P; Basu, R; Nemitz, I R; Rosenblatt, C; Iannacchione, G S

    2014-03-14

    It has been widely recognized that the combination of carbon nanotube (CNT) and liquid crystals (LCs) not only provides a useful way to align CNTs, but also dramatically enhances the order in the LC phases, which is especially useful in liquid crystal display (LCD) technology. As the measure of this phase behavior, the complex specific heat is presented over a wide temperature range for a negative dielectric anisotropy alkoxyphenylbenzoate liquid crystal (9OO4) and CNT composites as a function of CNT concentration. The calorimetric scans were performed under near-equilibrium conditions between 25 and 95 °C, first cooling and then followed by heating for CNT weight percent ranging from ϕ(w) = 0 to 0.2. All 9OO4/CNT mesophases have transition temperatures ~1 K higher and a crystallization temperature 4 K higher than that of the pure 9OO4. The crystal phase superheats until a strongly first-order specific heat feature is observed, 0.5 K higher than in the pure 9OO4. The transition enthalpy for the nanocomposite mesophases is 10% lower than that observed in the pure 9OO4. The strongly first-order crystallization and melting transition enthalpies are essentially constant over this range of ϕ(w). Complementary electroclinic measurement on a 0.05 wt. % sample, cooling towards the smectic-C phase from the smectic-A, indicates that the SmA-SmC transition remains mean-field-like in the presence of the CNTs. Given the homogeneous and random distribution of CNTs in these nanocomposites, we interpret these results as arising from the LC-CNT surface interaction pinning the orientational order uniformly along the CNT, without pinning the position of the 9OO4 molecule, leading to a net ordering effect for all phases. These effects of incorporating CNTs into LCs are likely due to "anisotropic orientational" coupling between CNT and LC, the change in the elastic properties of composites and thermal anisotropic properties of the CNTs. PMID:24628206

  20. Studies of nanocomposites of carbon nanotubes and a negative dielectric anisotropy liquid crystal

    NASA Astrophysics Data System (ADS)

    Kalakonda, P.; Basu, R.; Nemitz, I. R.; Rosenblatt, C.; Iannacchione, G. S.

    2014-03-01

    It has been widely recognized that the combination of carbon nanotube (CNT) and liquid crystals (LCs) not only provides a useful way to align CNTs, but also dramatically enhances the order in the LC phases, which is especially useful in liquid crystal display (LCD) technology. As the measure of this phase behavior, the complex specific heat is presented over a wide temperature range for a negative dielectric anisotropy alkoxyphenylbenzoate liquid crystal (9OO4) and CNT composites as a function of CNT concentration. The calorimetric scans were performed under near-equilibrium conditions between 25 and 95 °C, first cooling and then followed by heating for CNT weight percent ranging from ϕw = 0 to 0.2. All 9OO4/CNT mesophases have transition temperatures ˜1 K higher and a crystallization temperature 4 K higher than that of the pure 9OO4. The crystal phase superheats until a strongly first-order specific heat feature is observed, 0.5 K higher than in the pure 9OO4. The transition enthalpy for the nanocomposite mesophases is 10% lower than that observed in the pure 9OO4. The strongly first-order crystallization and melting transition enthalpies are essentially constant over this range of ϕw. Complementary electroclinic measurement on a 0.05 wt. % sample, cooling towards the smectic-C phase from the smectic-A, indicates that the SmA-SmC transition remains mean-field-like in the presence of the CNTs. Given the homogeneous and random distribution of CNTs in these nanocomposites, we interpret these results as arising from the LC-CNT surface interaction pinning the orientational order uniformly along the CNT, without pinning the position of the 9OO4 molecule, leading to a net ordering effect for all phases. These effects of incorporating CNTs into LCs are likely due to "anisotropic orientational" coupling between CNT and LC, the change in the elastic properties of composites and thermal anisotropic properties of the CNTs.

  1. 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.

  2. 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.

  3. Nonclassical light revealed by the joint statistics of simultaneous measurements.

    PubMed

    Luis, Alfredo

    2016-04-15

    Nonclassicality cannot be a single-observable property, since the statistics of any quantum observable is compatible with classical physics. We develop a general procedure to reveal nonclassical behavior of light states from the joint statistics arising in the practical measurement of multiple observables. Beside embracing previous approaches, this protocol can disclose nonclassical features for standard examples of classical-like behavior, such as SU(2) and Glauber coherent states. When combined with other criteria, this would imply that every light state is nonclassical.

  4. Indentation Tests Reveal Geometry-Regulated Stiffening of Nanotube Junctions.

    PubMed

    Ozden, Sehmus; Yang, Yang; Tiwary, Chandra Sekhar; Bhowmick, Sanjit; Asif, Syed; Penev, Evgeni S; Yakobson, Boris I; Ajayan, Pulickel M

    2016-01-13

    Here we report a unique method to locally determine the mechanical response of individual covalent junctions between carbon nanotubes (CNTs), in various configurations such as "X", "Y", and "Λ"-like. The setup is based on in situ indentation using a picoindenter integrated within a scanning electron microscope. This allows for precise mapping between junction geometry and mechanical behavior and uncovers geometry-regulated junction stiffening. Molecular dynamics simulations reveal that the dominant contribution to the nanoindentation response is due to the CNT walls stretching at the junction. Targeted synthesis of desired junction geometries can therefore provide a "structural alphabet" for construction of macroscopic CNT networks with tunable mechanical response. PMID:26618517

  5. The molecular architecture of axonemes revealed by cryoelectron tomography.

    PubMed

    Nicastro, Daniela; Schwartz, Cindi; Pierson, Jason; Gaudette, Richard; Porter, Mary E; McIntosh, J Richard

    2006-08-18

    Eukaryotic flagella and cilia are built on a 9 + 2 array of microtubules plus >250 accessory proteins, forming a biological machine called the axoneme. Here we describe the three-dimensional structure of rapidly frozen axonemes from Chlamydomonas and sea urchin sperm, using cryoelectron tomography and image processing to focus on the motor enzyme dynein. Our images suggest a model for the way dynein generates force to slide microtubules. They also reveal two dynein linkers that may provide "hard-wiring" to coordinate motor enzyme action, both circumferentially and along the axoneme. Periodic densities were also observed inside doublet microtubules; these may contribute to doublet stability. PMID:16917055

  6. Electronic properties of nanoentities revealed by electrically driven rotation

    PubMed Central

    Fan, D. L.; Zhu, Frank Q.; Xu, Xiaobin; Cammarata, Robert C.; Chien, C. L.

    2012-01-01

    Direct electric measurement via small contacting pads on individual quasi-one-dimensional nanoentities, such as nanowires and carbon nanotubes, are usually required to access its electronic properties. We show in this work that 1D nanoentities in suspension can be driven to rotation by AC electric fields. The chirality of the resultantrotation unambiguously reveals whether the nanoentities are metal, semiconductor, or insulator due to the dependence of the Clausius–Mossotti factor on the material conductivity and frequency. This contactless method provides rapid and parallel identification of the electrical characteristics of 1D nanoentities. PMID:22645373

  7. A Dilated Cardiomyopathy Revealing a Neuroblastoma: Which Link?

    PubMed

    Duhil de Bénazé, Gwenaelle; Iserin, Franck; Durand, Philippe; Schleiermacher, Gudrun; Orbach, Daniel

    2016-10-01

    Acute cardiac dysfunctions associated to neuroblastoma have rarely been reported. Cases already described are mainly related to high blood pressure, and rarely to an "acute catecholamine cardiomyopathy" more frequently found in adults with pheochromocytoma or secreting paraganglioma. We here report a case of an 8-month-old infant with severe acute cardiac failure with dilated cardiomyopathy and moderate ischemic myocardial signs, revealing a favorable histoprognosis neuroblastoma. After specific treatment, evolution was favorable, and cardiac function completely recovered. The association of reversible ischemic signs with high plasmatic level of catecholamines suggests the existence of a catecholamine-induced acute cardiac dysfunction which imitates a Tako-Tsubo syndrome in neuroblastoma.

  8. Missing piece of first-responder DNA repair machine revealed

    SciTech Connect

    2009-01-01

    Scientists from the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the Scripps Research Institute have revealed the role played by the least-understood part of a first-responder molecule that rushes in to bind and repair breaks in DNA strands, a process that helps people avoid cancer. With this final piece of the puzzle in place, scientists can better understand how the repair mechanism fends off cancer in healthy people, and conversely, how it helps cancer cells resist chemotherapy. This could enable researchers to develop more effective therapies with fewer side effects. http://newscenter.lbl.gov/press-releases/2009/10/01/dna-repair-uncovered/

  9. [Chronic septic granulomatosis in children revealed by invasive pulmonary aspergillosis].

    PubMed

    Zohra, Fitouri; Nadia, Matoussi; Nadia, Aloui; Khedija, Boussetta; Mouna, Chiha; Azza, Hammou; Saida, Ben Becher

    2005-11-01

    Chronic granulomatosis disease (GCD) is a hereditary abnormality of phagocytic cells, frequently revealed by invasive pulmonary Aspergillosis. The authors report the case of 8 year old girl investigates for hypotrophia, reccurent lung disease and hemoptysia. She was treated for pulmonary tuberculosis because of biological inflammatory syndrome, right alveolar opacity and positive tuberculin skin test. The course was marked by the developement of a thoracic wall mass. Anti- aspergillus serology was positive; culture of the thoracic mass puncture and bronchoalveolar lavage isolated fumigatus Aspergillus. GCD was suggested and confirmed by the NBT test.

  10. 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.

  11. Survey reveals nature of corrosion in HF alky units

    SciTech Connect

    Dobis, J.D. ); Clarida, D.R. ); Richert, J.P. )

    1995-03-06

    The results of a National Association of Corrosion Engineers survey of 62 HF alkylation units reveal relatively low incidence of service-related cracking of carbon steel. Hydrogen blistering, however, is prevalent, especially in the main acid circuit and overhead condensers. Based on these and other survey results, several recommendations are made to enable refiners to monitor and reduce corrosion in these special units. The paper discusses the survey results, construction materials, post-weld heat treatments, small-diameter piping, construction inspection, bolting, gaskets, block valves, maintenance practices, cracking, blistering, areas of vulnerability, and recommendations.

  12. Cohesin's role as an active chromatin domain anchorage revealed.

    PubMed

    Feig, Christine; Odom, Duncan T

    2013-12-11

    Cohesin is a conserved protein complex indispensible for proper cell division, because it secures sister-chromatid cohesion following DNA replication until segregation is required at the onset of anaphase. Recent studies have revealed functions beyond this, showing that cohesin binds to interphase chromatin regulating gene expression at select loci via long-range chromosomal interactions. In this issue of The EMBO Journal, Sofueva et al (2013) use a combination of chromatin conformation capture methods, classical FISH imaging, and loss-of-function studies to elegantly demonstrate how cohesin controls the 3D architectural organization of the genome.

  13. Revealing and Characterizing Dark Excitons through Coherent Multidimensional Spectroscopy.

    PubMed

    Tollerud, Jonathan O; Cundiff, Steven T; Davis, Jeffrey A

    2016-08-26

    Dark excitons are of fundamental importance in a broad range of contexts but are difficult to study using conventional optical spectroscopy due to their weak interaction with light. We show how coherent multidimensional spectroscopy can reveal and characterize dark states. Using this approach, we identify parity-forbidden and spatially indirect excitons in InGaAs/GaAs quantum wells and determine details regarding lifetimes, homogeneous and inhomogeneous linewidths, broadening mechanisms, and coupling strengths. The observations of coherent coupling between these states and bright excitons hint at a role for a multistep process by which excitons in the barrier can relax into the quantum wells. PMID:27610881

  14. A Dilated Cardiomyopathy Revealing a Neuroblastoma: Which Link?

    PubMed

    Duhil de Bénazé, Gwenaelle; Iserin, Franck; Durand, Philippe; Schleiermacher, Gudrun; Orbach, Daniel

    2016-10-01

    Acute cardiac dysfunctions associated to neuroblastoma have rarely been reported. Cases already described are mainly related to high blood pressure, and rarely to an "acute catecholamine cardiomyopathy" more frequently found in adults with pheochromocytoma or secreting paraganglioma. We here report a case of an 8-month-old infant with severe acute cardiac failure with dilated cardiomyopathy and moderate ischemic myocardial signs, revealing a favorable histoprognosis neuroblastoma. After specific treatment, evolution was favorable, and cardiac function completely recovered. The association of reversible ischemic signs with high plasmatic level of catecholamines suggests the existence of a catecholamine-induced acute cardiac dysfunction which imitates a Tako-Tsubo syndrome in neuroblastoma. PMID:27571126

  15. Revealing and Characterizing Dark Excitons through Coherent Multidimensional Spectroscopy

    NASA Astrophysics Data System (ADS)

    Tollerud, Jonathan O.; Cundiff, Steven T.; Davis, Jeffrey A.

    2016-08-01

    Dark excitons are of fundamental importance in a broad range of contexts but are difficult to study using conventional optical spectroscopy due to their weak interaction with light. We show how coherent multidimensional spectroscopy can reveal and characterize dark states. Using this approach, we identify parity-forbidden and spatially indirect excitons in InGaAs/GaAs quantum wells and determine details regarding lifetimes, homogeneous and inhomogeneous linewidths, broadening mechanisms, and coupling strengths. The observations of coherent coupling between these states and bright excitons hint at a role for a multistep process by which excitons in the barrier can relax into the quantum wells.

  16. Pneumoretroperitoneum and Pneumomediastinum Revealing a Left Colon Perforation

    PubMed Central

    Montori, Giulia; Di Giovanni, Giacomo; Mzoughi, Zeineb; Angot, Cedric; Al Samman, Sophie; Solaini, Leonardo; Cheynel, Nicolas

    2015-01-01

    Left colon perforation usually occurs in complicated diverticulitis or cancer. The most frequent signs are intraperitoneal abscess or peritonitis. In cases of retroperitoneal colonic perforation, diagnosis may be difficult. A 59-year-old woman presented with left thigh pain and with abdominal discomfort associated with mild dyspnea. Computed tomography scan showed air bubbles and purulent collection in the retroperitoneum, with subcutaneous emphysema extending from the left thigh to the neck. Computed tomography scan also revealed portal vein gas and thrombosis with multiple liver abscesses. An emergency laparotomy revealed a perforation of the proximal left colon. No masses were found. A left colectomy was performed. The retroperitoneum was drained and washed extensively. A negative pressure wound therapy was applied. A second-look laparotomy was performed 48 hours later. The retroperitoneum was drained and an end colostomy was performed. Intensive Care Unit postoperative stay was 9 days, and the patient was discharged on the 32nd postoperative day. Pneumoretroperitoneum and pneumomediastinum are rare signs of colonic retroperitoneal perforation. The diagnosis may be delayed, especially in the absence of peritoneal irritation. Clinical, laboratory, and especially radiologic parameters might be useful. Surgical treatment must be prompt to improve prognosis. PMID:26414818

  17. Parallel lipoplex folding pathways revealed using magnetic tweezers

    PubMed Central

    Sun, Zhiqiang; Tikhonova, Elena B.; Zgurskaya, Helen I.; Rybenkov, Valentin V.

    2012-01-01

    Lipid-coated DNA nanoparticles (lipoplexes) are a powerful gene delivery tool with promising therapeutic applications. The mechanism of lipoplex assembly remains poorly understood. We explored DNA packing by a cationic lipid DSTAP (distearoyl trimethylammonium-propane) using magnetic tweezers. DSTAP-induced DNA condensation occurred as a series of bursts with the mean step size of 60 nm to 80 nm. The pause time preceding the steps could be approximated as a bimodal distribution, which reveals at least two distinct condensation pathways. The rapidly condensed DNA was more resilient to force-induced decondensation. The proportion of the stable, fast-formed complexes decreased at high salt concentrations. A similar trend was observed in bulk experiments. Lipoplexes assembled at low salt concentration more efficiently shielded DNA from fluorescent dyes and DNase even after transfer to the high salt conditions. These data reveal that lipoplex folding occurs via two parallel pathways even at the single molecule level. The progress through the two pathways can be monitored in real time using single DNA manipulations. The relative efficiency of the two pathways can be varied by external conditions. PMID:22988939

  18. Direct visualization reveals kinetics of meiotic chromosome synapsis

    DOE PAGESBeta

    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

  19. 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.

  20. 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. PMID:24043814

  1. Microsporidian genome analysis reveals evolutionary strategies for obligate intracellular growth.

    PubMed

    Cuomo, Christina A; Desjardins, Christopher A; Bakowski, Malina A; Goldberg, Jonathan; Ma, Amy T; Becnel, James J; Didier, Elizabeth S; Fan, Lin; Heiman, David I; Levin, Joshua Z; Young, Sarah; Zeng, Qiandong; Troemel, Emily R

    2012-12-01

    Microsporidia comprise a large phylum of obligate intracellular eukaryotes that are fungal-related parasites responsible for widespread disease, and here we address questions about microsporidia biology and evolution. We sequenced three microsporidian genomes from two species, Nematocida parisii and Nematocida sp1, which are natural pathogens of Caenorhabditis nematodes and provide model systems for studying microsporidian pathogenesis. We performed deep sequencing of transcripts from a time course of N. parisii infection. Examination of pathogen gene expression revealed compact transcripts and a dramatic takeover of host cells by Nematocida. We also performed phylogenomic analyses of Nematocida and other microsporidian genomes to refine microsporidian phylogeny and identify evolutionary events of gene loss, acquisition, and modification. In particular, we found that all microsporidia lost the tumor-suppressor gene retinoblastoma, which we speculate could accelerate the parasite cell cycle and increase the mutation rate. We also found that microsporidia acquired transporters that could import nucleosides to fuel rapid growth. In addition, microsporidian hexokinases gained secretion signal sequences, and in a functional assay these were sufficient to export proteins out of the cell; thus hexokinase may be targeted into the host cell to reprogram it toward biosynthesis. Similar molecular changes appear during formation of cancer cells and may be evolutionary strategies adopted independently by microsporidia to proliferate rapidly within host cells. Finally, analysis of genome polymorphisms revealed evidence for a sexual cycle that may provide genetic diversity to alleviate problems caused by clonal growth. Together these events may explain the emergence and success of these diverse intracellular parasites.

  2. Economic Choices Reveal Probability Distortion in Macaque Monkeys

    PubMed Central

    Lak, Armin; Bossaerts, Peter; Schultz, Wolfram

    2015-01-01

    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. PMID:25698750

  3. NeuCode Proteomics Reveals Bap1 Regulation of Metabolism.

    PubMed

    Baughman, Joshua M; Rose, Christopher M; Kolumam, Ganesh; Webster, Joshua D; Wilkerson, Emily M; Merrill, Anna E; Rhoads, Timothy W; Noubade, Rajkumar; Katavolos, Paula; Lesch, Justin; Stapleton, Donald S; Rabaglia, Mary E; Schueler, Kathy L; Asuncion, Raymond; Domeyer, Melanie; Zavala-Solorio, Jose; Reich, Michael; DeVoss, Jason; Keller, Mark P; Attie, Alan D; Hebert, Alexander S; Westphall, Michael S; Coon, Joshua J; Kirkpatrick, Donald S; Dey, Anwesha

    2016-07-12

    We introduce neutron-encoded (NeuCode) amino acid labeling of mice as a strategy for multiplexed proteomic analysis in vivo. Using NeuCode, we characterize an inducible knockout mouse model of Bap1, a tumor suppressor and deubiquitinase whose in vivo roles outside of cancer are not well established. NeuCode proteomics revealed altered metabolic pathways following Bap1 deletion, including profound elevation of cholesterol biosynthetic machinery coincident with reduced expression of gluconeogenic and lipid homeostasis proteins in liver. Bap1 loss increased pancreatitis biomarkers and reduced expression of mitochondrial proteins. These alterations accompany a metabolic remodeling with hypoglycemia, hypercholesterolemia, hepatic lipid loss, and acinar cell degeneration. Liver-specific Bap1 null mice present with fully penetrant perinatal lethality, severe hypoglycemia, and hepatic lipid deficiency. This work reveals Bap1 as a metabolic regulator in liver and pancreas, and it establishes NeuCode as a reliable proteomic method for deciphering in vivo biology. PMID:27373151

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Piriform Spider Silk Sequences Reveal Unique Repetitive Elements

    PubMed Central

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

    2010-01-01

    Orb-weaving spider silk fibers are assembled from very large, highly repetitive proteins. The repeated segments contain, in turn, short, simple 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 to 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 messenger RNA is larger than 11kb 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 pirifom sequences form an ortholog group. PMID:20954740

  9. Circulating protein synthesis rates reveal skeletal muscle proteome dynamics

    PubMed Central

    Shankaran, Mahalakshmi; King, Chelsea L.; Angel, Thomas E.; Holmes, William E.; Li, Kelvin W.; Colangelo, Marc; Price, John C.; Turner, Scott M.; Bell, Christopher; Hamilton, Karyn L.; Miller, Benjamin F.; Hellerstein, Marc K.

    2015-01-01

    Here, we have described and validated a strategy for monitoring skeletal muscle protein synthesis rates in rodents and humans over days or weeks from blood samples. We based this approach on label incorporation into proteins that are synthesized specifically in skeletal muscle and escape into the circulation. Heavy water labeling combined with sensitive tandem mass spectrometric analysis allowed integrated synthesis rates of proteins in muscle tissue across the proteome to be measured over several weeks. Fractional synthesis rate (FSR) of plasma creatine kinase M-type (CK-M) and carbonic anhydrase 3 (CA-3) in the blood, more than 90% of which is derived from skeletal muscle, correlated closely with FSR of CK-M, CA-3, and other proteins of various ontologies in skeletal muscle tissue in both rodents and humans. Protein synthesis rates across the muscle proteome generally changed in a coordinate manner in response to a sprint interval exercise training regimen in humans and to denervation or clenbuterol treatment in rodents. FSR of plasma CK-M and CA-3 revealed changes and interindividual differences in muscle tissue proteome dynamics. In human subjects, sprint interval training primarily stimulated synthesis of structural and glycolytic proteins. Together, our results indicate that this approach provides a virtual biopsy, sensitively revealing individualized changes in proteome-wide synthesis rates in skeletal muscle without a muscle biopsy. Accordingly, this approach has potential applications for the diagnosis, management, and treatment of muscle disorders. PMID:26657858

  10. Pneumoretroperitoneum and Pneumomediastinum Revealing a Left Colon Perforation.

    PubMed

    Montori, Giulia; Di Giovanni, Giacomo; Mzoughi, Zeineb; Angot, Cedric; Al Samman, Sophie; Solaini, Leonardo; Cheynel, Nicolas

    2015-06-01

    Left colon perforation usually occurs in complicated diverticulitis or cancer. The most frequent signs are intraperitoneal abscess or peritonitis. In cases of retroperitoneal colonic perforation, diagnosis may be difficult. A 59-year-old woman presented with left thigh pain and with abdominal discomfort associated with mild dyspnea. Computed tomography scan showed air bubbles and purulent collection in the retroperitoneum, with subcutaneous emphysema extending from the left thigh to the neck. Computed tomography scan also revealed portal vein gas and thrombosis with multiple liver abscesses. An emergency laparotomy revealed a perforation of the proximal left colon. No masses were found. A left colectomy was performed. The retroperitoneum was drained and washed extensively. A negative pressure wound therapy was applied. A second-look laparotomy was performed 48 hours later. The retroperitoneum was drained and an end colostomy was performed. Intensive Care Unit postoperative stay was 9 days, and the patient was discharged on the 32nd postoperative day. Pneumoretroperitoneum and pneumomediastinum are rare signs of colonic retroperitoneal perforation. The diagnosis may be delayed, especially in the absence of peritoneal irritation. Clinical, laboratory, and especially radiologic parameters might be useful. Surgical treatment must be prompt to improve prognosis.

  11. 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

  12. 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.

  13. Nanoscience of single polymer chains revealed by nanofishing.

    PubMed

    Nakajima, Ken; Nishi, Toshio

    2006-01-01

    The invention of atomic force microscopy (AFM) enabled us to study the statistical properties of single polymer chains by a method called "nanofishing," which stretches a single polymer chain adsorbed on a substrate with its one end by picking it at the other end. A force-extension curve obtained for a single polystyrene chain in a Theta solvent (cyclohexane) shows good agreement with a worm-like chain model and, therefore, gives microscopic information about entropic elasticity. Furthermore, the nanofishing technique can be used for dynamic viscoelastic measurement of single polymer chains. An AFM cantilever is mechanically oscillated at its resonant frequency during the stretching process. This technique enables the estimation of quantitative and simultaneous elongation-dependent changes of stiffness and viscosity of a single chain with the use of a phenomenological model. In this study, the effect of solvent on viscosity in low extension regions reveals that the viscosity is attributed to monomer-solvent friction. Thus, static and dynamic nanofishing techniques are shown to give powerful experimental proofs for several basic questions in polymer physics. The techniques are expected to reveal hidden properties of polymer chains or polymer solutions by any types of macroscopic measurements in the future. PMID:17099889

  14. 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].

  15. Layer-Specific Intracortical Connectivity Revealed with Diffusion MRI

    PubMed Central

    Leuze, Christoph W.U.; Anwander, Alfred; Bazin, Pierre-Louis; Dhital, Bibek; Stüber, Carsten; Reimann, Katja; Geyer, Stefan; Turner, Robert

    2014-01-01

    In this work, we show for the first time that the tangential diffusion component is orientationally coherent at the human cortical surface. Using diffusion magnetic resonance imaging (dMRI), we have succeeded in tracking intracortical fiber pathways running tangentially within the cortex. In contrast with histological methods, which reveal little regarding 3-dimensional organization in the human brain, dMRI delivers additional understanding of the layer dependence of the fiber orientation. A postmortem brain block was measured at very high angular and spatial resolution. The dMRI data had adequate resolution to allow analysis of the fiber orientation within 4 notional cortical laminae. We distinguished a lamina at the cortical surface where diffusion was tangential along the surface, a lamina below the surface where diffusion was mainly radial, an internal lamina covering the Stria of Gennari, where both strong radial and tangential diffusion could be observed, and a deep lamina near the white matter, which also showed mainly radial diffusion with a few tangential compartments. The measurement of the organization of the tangential diffusion component revealed a strong orientational coherence at the cortical surface. PMID:23099298

  16. 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

  17. Are Extreme T Dwarf Color Outliers Revealing Their Ages?

    NASA Astrophysics Data System (ADS)

    Mace, Gregory N.

    2014-01-01

    Brown dwarfs emerge as the low-mass products of the star formation process and then continue to cool. Those with temperatures between 500-1000K correspond to late-type T dwarf (≥ T7) spectral types. Using the Wide-field Infrared Survey Explorer (WISE) we have septupled the number of T dwarfs in this temperature regime, thereby creating a sizable sample with which to study overall trends and to identify outliers. I will present my spectrophotometric studies of this expanded population and compare the WISE discoveries to the samples revealed by 2MASS and UKIDSS. Additionally, I will discuss the newly discovered T8 subdwarf companion to Wolf 1130 and its utility as a high-gravity, low-metallicity benchmark. Late-type T dwarfs with redder J-H and bluer Y-J colors, as well as suppressed K-band flux, are likely revealing their old age. A broad survey of the most extreme late-type T dwarf color outliers can provide useful indicators of physical parameters. These indicators can then be applied to the diverse sample of directly imaged exoplanet and Y dwarf discoveries.

  18. 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

  19. Piriform spider silk sequences reveal unique repetitive elements.

    PubMed

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

    2010-11-01

    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.

  20. Revealing short-period normal modes of the atmosphere

    NASA Astrophysics Data System (ADS)

    Shved, G. M.; Ermolenko, S. I.; Hoffmann, P.

    2015-09-01

    Barometer and seismometer measurements at Collm, Germany (51.3° N, 13.0° E) for all of 2002 are used to search for atmospheric normal modes (ANMs) in the frequency range 50-310 µHz. The measurements are spectrally analyzed using a 5-day window sliding along the 1-year series with a 1-day step. The subsequent analysis follows two procedures: (a) revealing features in the frequency distribution of the number of statistically significant spectral peaks in histograms built on the basis of these spectra and (b) calculating the multiplication spectra for the raw spectra. The two procedures yield the same result for the two instruments, i.e., reveal a periodicity in the clustering of atmospheric modes on the frequency axis with a period of ˜6 µHz. The fact that this period is close to 7 μHz, which is predicted by the crude theory of gravity—inertia ANMs [3] for their frequency distribution, suggests that ANMs are generated down to as small a period as ˜1 h.

  1. Phylogenetic analysis reveals the surprising diversity of an oxygenase class.

    PubMed

    Capyk, Jenna K; Eltis, Lindsay D

    2012-03-01

    As metalloenzymes capable of transforming a broad range of substrates with high stereo- and regio-specificity, the multicomponent Rieske oxygenases (ROs) have been studied in bacterial systems for applications in bioremediation and industrial biocatalysis. These studies include genetic and biochemical investigations, determination of enzyme structure, phylogenetic analysis, and enzyme classification. Although RO terminal oxygenase components (RO-Os) share a conserved domain structure, their sequences are highly divergent and present significant challenges for identification and classification. Herein, we present the first global phylogenetic analysis of a broad range of RO-Os from diverse taxonomic groups. We employed objective, structure-based criteria to significantly reduce the inclusion of erroneously aligned sequences in the analysis. Our findings reveal that RO biochemical studies to date have been largely concentrated in an unexpectedly narrow portion of the RO-O sequence landscape. Additionally, our analysis demonstrates the existence two distinct groups of RO-O sequences. Finally, the sequence diversity recognized in this study necessitates a new RO-O classification scheme. We therefore propose a P450-like naming system. Our results reveal a diversity of sequence and potential catalytic functionality that has been wholly unappreciated in the RO literature. This study also demonstrates that many commonly used bioinformatic tools may not be sufficient to analyze the vast amount of data available in current databases. These findings facilitate the expanded exploration of RO catalytic capabilities in both biological and technological contexts and increase the potential for practical exploitation of their activities.

  2. Comparison of supramolecular hydrogen bonded liquid crystals

    NASA Astrophysics Data System (ADS)

    Pongali Sathya Prabu, N.; Vijayakumar, V. N.; Madhu Mohan, M. L. N.

    2012-01-01

    Supramolecular hydrogen bonded liquid crystals are formed by methoxy hydroquinone (MHQ) and alkyloxy benzoic acids are isolated and characterised. MHQ formed double hydrogen bonds with p-n-alkyloxy benzoic acids. Fourier Transform-Infrared studies confirm the hydrogen bond formation in the complex. Polarising Optical Microscopic (POM) studies revealed the textural information, while the transition and enthalpy values are experimentally deduced from Differential Scanning Calorimetry (DSC) studies. Phase diagram has been constructed from the POM and DSC data, respectively. Experimental data of optical tilt angle in Smectic C phase have been fitted to a power law and it has been observed that the temperature variation of the tilt angle follows Mean Field theory prediction. Present homologous are compared with hydroquinone alkyloxy benzoic acids complexes and the influence of methyl group on the occurrence of phases and its transition temperatures are discussed.

  3. Deciphering CAPTCHAs: what a Turing test reveals about human cognition.

    PubMed

    Hannagan, Thomas; Ktori, Maria; Chanceaux, Myriam; Grainger, Jonathan

    2012-01-01

    Turning Turing's logic on its head, we used widespread letter-based Turing Tests found on the internet (CAPTCHAs) to shed light on human cognition. We examined the basis of the human ability to solve CAPTCHAs, where machines fail. We asked whether this is due to our use of slow-acting inferential processes that would not be available to machines, or whether fast-acting automatic orthographic processing in humans has superior robustness to shape variations. A masked priming lexical decision experiment revealed efficient processing of CAPTCHA words in conditions that rule out the use of slow inferential processing. This shows that the human superiority in solving CAPTCHAs builds on a high degree of invariance to location and continuous transforms, which is achieved during the very early stages of visual word recognition in skilled readers. PMID:22396750

  4. 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. PMID:26523505

  5. 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.

  6. Synthetic protein interactions reveal a functional map of the cell

    PubMed Central

    Berry, Lisa K; Ólafsson, Guðjón; Ledesma-Fernández, Elena; Thorpe, Peter H

    2016-01-01

    To understand the function of eukaryotic cells, it is critical to understand the role of protein-protein interactions and protein localization. Currently, we do not know the importance of global protein localization nor do we understand to what extent the cell is permissive for new protein associations – a key requirement for the evolution of new protein functions. To answer this question, we fused every protein in the yeast Saccharomyces cerevisiae with a partner from each of the major cellular compartments and quantitatively assessed the effects upon growth. This analysis reveals that cells have a remarkable and unanticipated tolerance for forced protein associations, even if these associations lead to a proportion of the protein moving compartments within the cell. Furthermore, the interactions that do perturb growth provide a functional map of spatial protein regulation, identifying key regulatory complexes for the normal homeostasis of eukaryotic cells. DOI: http://dx.doi.org/10.7554/eLife.13053.001 PMID:27098839

  7. Complex kinetics of DNA condensation revealed through DNA twist tracing.

    PubMed

    Li, Wei; Wong, Wei Juan; Lim, Ci Ji; Ju, Hai-Peng; Li, Ming; Yan, Jie; Wang, Peng-Ye

    2015-08-01

    Toroid formation is an important mechanism for DNA condensation in cells. The length change during DNA condensation was investigated in previous single-molecule experiments. However, DNA twist is key to understanding the topological kinetics of DNA condensation. In this study, DNA twist as well as DNA length was traced during the DNA condensation by the freely orbiting magnetic tweezers and the tilted magnetic tweezers combined with Brownian dynamics simulations. The experimental results disclose the complex relationship between DNA extension and backbone rotation. Brownian dynamics simulations show that the toroid formation follows a wiggling pathway which leads to the complex DNA backbone rotation as revealed in our experiments. These findings provide the complete description of multivalent cation-dependent DNA toroid formation under tension.

  8. Phosphoproteome Integration Reveals Patient-Specific Networks in Prostate Cancer.

    PubMed

    Drake, Justin M; Paull, Evan O; Graham, Nicholas A; Lee, John K; Smith, Bryan A; Titz, Bjoern; Stoyanova, Tanya; Faltermeier, Claire M; Uzunangelov, Vladislav; Carlin, Daniel E; Fleming, Daniel Teo; Wong, Christopher K; Newton, Yulia; Sudha, Sud; Vashisht, Ajay A; Huang, Jiaoti; Wohlschlegel, James A; Graeber, Thomas G; Witte, Owen N; Stuart, Joshua M

    2016-08-11

    We used clinical tissue from lethal metastatic castration-resistant prostate cancer (CRPC) patients obtained at rapid autopsy to evaluate diverse genomic, transcriptomic, and phosphoproteomic datasets for pathway analysis. Using Tied Diffusion through Interacting Events (TieDIE), we integrated differentially expressed master transcriptional regulators, functionally mutated genes, and differentially activated kinases in CRPC tissues to synthesize a robust signaling network consisting of druggable kinase pathways. Using MSigDB hallmark gene sets, six major signaling pathways with phosphorylation of several key residues were significantly enriched in CRPC tumors after incorporation of phosphoproteomic data. Individual autopsy profiles developed using these hallmarks revealed clinically relevant pathway information potentially suitable for patient stratification and targeted therapies in late stage prostate cancer. Here, we describe phosphorylation-based cancer hallmarks using integrated personalized signatures (pCHIPS) that shed light on the diversity of activated signaling pathways in metastatic CRPC while providing an integrative, pathway-based reference for drug prioritization in individual patients. PMID:27499020

  9. 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.

  10. Topological structure dynamics revealing collective evolution in active nematics

    PubMed Central

    Shi, Xia-qing; Ma, Yu-qiang

    2013-01-01

    Topological defects frequently emerge in active matter like bacterial colonies, cytoskeleton extracts on substrates, self-propelled granular or colloidal layers and so on, but their dynamical properties and the relations to large-scale organization and fluctuations in these active systems are seldom touched. Here we reveal, through a simple model for active nematics using self-driven hard elliptic rods, that the excitation, annihilation and transportation of topological defects differ markedly from those in non-active media. These dynamical processes exhibit strong irreversibility in active nematics in the absence of detailed balance. Moreover, topological defects are the key factors in organizing large-scale dynamic structures and collective flows, resulting in multi-spatial temporal effects. These findings allow us to control the self-organization of active matter through topological structures. PMID:24346733

  11. 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.

  12. Pupillometry reveals reduced unconscious emotional reactivity in autism.

    PubMed

    Nuske, Heather J; Vivanti, Giacomo; Hudry, Kristelle; Dissanayake, Cheryl

    2014-09-01

    Recent theoretical conceptualisations have suggested that emotion processing impairments in autism stem from disruption to the sub-cortical, rapid emotion-processing system. We argue that a clear way to ascertain whether this system is affected in autism is by measuring unconscious emotional reactivity. Using backwards masking, we presented fearful expressions non-consciously (subliminally) as well as consciously (supraliminally), and measured pupillary responses as an index of emotional reactivity in 19 children with autism and 19 typically developing children, aged 2-5 years. The pupillary responses of the children with autism revealed reduced unconscious emotional reactivity, with no group differences on consciously presented emotion. Together, these results indicate a hyporesponsiveness to non-consciously presented emotion suggesting a fundamental difference in emotion processing in autism, which requires consciousness and more time. PMID:25017502

  13. Geophysical imaging reveals topographic stress control of bedrock weathering.

    PubMed

    St Clair, J; Moon, S; Holbrook, W S; Perron, J T; Riebe, C S; Martel, S J; Carr, B; Harman, C; Singha, K; Richter, D deB

    2015-10-30

    Bedrock fracture systems facilitate weathering, allowing fresh mineral surfaces to interact with corrosive waters and biota from Earth's surface, while simultaneously promoting drainage of chemically equilibrated fluids. We show that topographic perturbations to regional stress fields explain bedrock fracture distributions, as revealed by seismic velocity and electrical resistivity surveys from three landscapes. The base of the fracture-rich zone mirrors surface topography where the ratio of horizontal compressive tectonic stresses to near-surface gravitational stresses is relatively large, and it parallels the surface topography where the ratio is relatively small. Three-dimensional stress calculations predict these results, suggesting that tectonic stresses interact with topography to influence bedrock disaggregation, groundwater flow, chemical weathering, and the depth of the "critical zone" in which many biogeochemical processes occur. PMID:26516279

  14. How actions create--not just reveal--preferences.

    PubMed

    Ariely, Dan; Norton, Michael I

    2008-01-01

    The neo-classical economics view that behavior is driven by - and reflective of - hedonic utility is challenged by psychologists' demonstrations of cases in which actions do not merely reveal preferences but rather create them. In this view, preferences are frequently constructed in the moment and are susceptible to fleeting situational factors; problematically, individuals are insensitive to the impact of such factors on their behavior, misattributing utility caused by these irrelevant factors to stable underlying preferences. Consequently, subsequent behavior might reflect not hedonic utility but rather this erroneously imputed utility that lingers in memory. Here we review the roles of these streams of utility in shaping preferences, and discuss how neuroimaging offers unique possibilities for disentangling their independent contributions to behavior.

  15. Structural characterization of human heparanase reveals insights into substrate recognition

    PubMed Central

    Wu, Liang; Viola, Cristina M.; Brzozowski, Andrzej M.; Davies, Gideon J.

    2016-01-01

    Heparan Sulfate (HS) is a glycosaminoglycan (GAG) which forms a key component of the extracellular matrix (ECM). Breakdown of HS is carried out by heparanase (HPSE), an endo-β-glucuronidase of the glycoside hydrolase (GH)79 family. Overexpression of HPSE is strongly linked to cancer metastases - reflecting breakdown of extracellular HS and release of stored growth factors. Here we present crystal structures of human HPSE at 1.6-1.9 Å resolution reveal how an endo-acting binding cleft is exposed by proteolytic activation of latent proHPSE. Oligosaccharide complexes map the substrate-binding and sulfate recognition motifs. These data shed light on the structure and interactions for a key enzyme involved in ECM maintenance, and provide a starting point for design of HPSE inhibitors as biochemical tools and anti-cancer therapeutics. PMID:26575439

  16. 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.

  17. 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. PMID:26390033

  18. 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

  19. Central tolerance to self revealed by the autoimmune regulator.

    PubMed

    Chan, Alice Y; Anderson, Mark S

    2015-11-01

    The autoimmune regulator (Aire) was initially identified as the gene causing multiorgan system autoimmunity in humans, and deletion of this gene in mice also resulted in organ-specific autoimmunity. Aire regulates the expression of tissue-specific antigens (TSAs) in medullary thymic epithelial cells (mTECs), which play a critical role in the negative selection of autoreactive T cells and the generation of regulatory T cells. More recently, the role of Aire in the development of mTECs has helped elucidate its ability to present the spectrum of TSAs needed to prevent autoimmunity. Molecular characterization of the functional domains of Aire has revealed multiple binding partners that assist Aire's function in altering gene transcription and chromatin remodeling. These recent advances have further highlighted the importance of Aire in central tolerance. PMID:26579596

  20. The genome of Tetranychus urticae reveals herbivorous pest adaptations.

    PubMed

    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

    2011-11-23

    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.

  1. Personal Omics Profiling Reveals Dynamic Molecular and Medical Phenotypes

    PubMed Central

    Chen, Rui; Mias, George I.; Li-Pook-Than, Jennifer; Jiang, Lihua; Lam, Hugo Y. K.; Chen, Rong; Miriami, Elana; Karczewski, Konrad J.; Hariharan, Manoj; Dewey, Frederick E.; Cheng, Yong; Clark, Michael J.; Im, Hogune; Habegger, Lukas; Balasubramanian, Suganthi; O'Huallachain, Maeve; Dudley, Joel T.; Hillenmeyer, Sara; Haraksingh, Rajini; Sharon, Donald; Euskirchen, Ghia; Lacroute, Phil; Bettinger, Keith; Boyle, Alan P.; Kasowski, Maya; Grubert, Fabian; Seki, Scott; Garcia, Marco; Whirl-Carrillo, Michelle; Gallardo, Mercedes; Blasco, Maria A.; Greenberg, Peter L.; Snyder, Phyllis; Klein, Teri E.; Altman, Russ B.; Butte, Atul; Ashley, Euan A.; Nadeau, Kari C.; Gerstein, Mark; Tang, Hua; Snyder, Michael

    2012-01-01

    SUMMARY Personalized medicine is expected to benefit from combining genomic information with regular monitoring of physiological states by multiple high-throughput methods. Here we present an integrative Personal Omics Profile (iPOP), an analysis that combines genomic, transcriptomic, proteomic, metabolomic, and autoantibody profiles from a single individual over a 14-month period. Our iPOP analysis revealed various medical risks, including Type II diabetes. It also uncovered extensive, dynamic changes in diverse molecular components and biological pathways across healthy and diseased conditions. Extremely high coverage genomic and transcriptomic data, which provide the basis of our iPOP, discovered extensive heteroallelic changes during healthy and diseased states and an unexpected RNA editing mechanism. This study demonstrates that longitudinal iPOP can be used to interpret healthy and disease states by connecting genomic information with additional dynamic omics activity. PMID:22424236

  2. 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

  3. Towards revealing the functions of all genes in plants.

    PubMed

    Rhee, Seung Yon; Mutwil, Marek

    2014-04-01

    The great recent progress made in identifying the molecular parts lists of organisms revealed the paucity of our understanding of what most of the parts do. In this review, we introduce computational and statistical approaches and omics data used for inferring gene function in plants, with an emphasis on network-based inference. We also discuss caveats associated with network-based function predictions such as performance assessment, annotation propagation, the guilt-by-association concept, and the meaning of hubs. Finally, we note the current limitations and possible future directions such as the need for gold standard data from several species, unified access to data and tools, quantitative comparison of data and tool quality, and high-throughput experimental validation platforms for systematic gene function elucidation in plants.

  4. 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.

  5. An adaptive perspective on revealed and concealed cues to empathy.

    PubMed

    Ward, Robert; Shingler, Polly

    2016-02-01

    Wu, Sheppard, and Mitchell (Br. J. Psychol., 2016; 107, 1-22) found that observers could accurately identify people with extreme but not more average empathy scores. Here, we further consider this U-shaped discrimination function. We first examine a statistical issue regarding the construction of the average groups, which are less homogenous by definition than the extreme groups. We then consider the kinds of questions arising when these results are considered within the adaptive framework of signal theory. Some interesting questions arise relating to the signal sender, including the costs and benefits to the sender in revealing and concealing true empathy levels, and the effects of adopting behavioural norms to conceal true levels of empathy.

  6. Geophysical imaging reveals topographic stress control of bedrock weathering.

    PubMed

    St Clair, J; Moon, S; Holbrook, W S; Perron, J T; Riebe, C S; Martel, S J; Carr, B; Harman, C; Singha, K; Richter, D deB

    2015-10-30

    Bedrock fracture systems facilitate weathering, allowing fresh mineral surfaces to interact with corrosive waters and biota from Earth's surface, while simultaneously promoting drainage of chemically equilibrated fluids. We show that topographic perturbations to regional stress fields explain bedrock fracture distributions, as revealed by seismic velocity and electrical resistivity surveys from three landscapes. The base of the fracture-rich zone mirrors surface topography where the ratio of horizontal compressive tectonic stresses to near-surface gravitational stresses is relatively large, and it parallels the surface topography where the ratio is relatively small. Three-dimensional stress calculations predict these results, suggesting that tectonic stresses interact with topography to influence bedrock disaggregation, groundwater flow, chemical weathering, and the depth of the "critical zone" in which many biogeochemical processes occur.

  7. 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.

  8. High Frequency Monitoring Reveals Aftershocks in Subcritical Crack Growth

    NASA Astrophysics Data System (ADS)

    Stojanova, M.; Santucci, S.; Vanel, L.; Ramos, O.

    2014-03-01

    By combining direct imaging and acoustic emission measurements, the subcritical propagation of a crack in a heterogeneous material is analyzed. Both methods show that the fracture proceeds through a succession of discrete events. However, the macroscopic opening of the fracture captured by the images results from the accumulation of more-elementary events detected by the acoustics. When the acoustic energy is cumulated over large time scales corresponding to the image acquisition rate, a similar statistics is recovered. High frequency acoustic monitoring reveals aftershocks responsible for a time scale dependent exponent of the power law energy distributions. On the contrary, direct imaging, which is unable to resolve these aftershocks, delivers a misleading exponent value.

  9. Anisotropic MRI contrast reveals enhanced ionic transport in plastic crystals.

    PubMed

    Romanenko, Konstantin; Jin, Liyu; Madsen, Louis A; Pringle, Jennifer M; O'Dell, Luke A; Forsyth, Maria

    2014-11-01

    Organic ionic plastic crystals (OIPCs) are attractive as solid-state electrolytes for electrochemical devices such as lithium-ion batteries and solar and fuel cells. OIPCs offer high ionic conductivity, nonflammability, and versatility of molecular design. Nevertheless, intrinsic ion transport behavior of OIPCs is not fully understood, and their measured properties depend heavily on thermal history. Solid-state magnetic resonance imaging experiments reveal a striking image contrast anisotropy sensitive to the orientation of grain boundaries in polycrystalline OIPCs. Probing triethyl(methyl)phosphonium bis(fluorosulfonyl)imide (P1222FSI) samples with different thermal history demonstrates vast variations in microcrystallite alignment. Upon slow cooling from the melt, microcrystallites exhibit a preferred orientation throughout the entire sample, leading to an order of magnitude increase in conductivity as probed using impedance spectroscopy. This investigation describes both a new conceptual window and a new characterization method for understanding polycrystalline domain structure and transport in plastic crystals and other solid-state conductors. PMID:25312993

  10. 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.

  11. 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. PMID:25504712

  12. Stardust is revealed after a protective canister is removed

    NASA Technical Reports Server (NTRS)

    1999-01-01

    At Launch Pad 17-A, Cape Canaveral Air Station, the Stardust spacecraft is revealed after removal of a protective canister. Stardust is targeted for launch on Feb. 6 aboard a Boeing Delta II rocket. The spacecraft is destined for a close encounter with the comet Wild 2 in January 2004. Using a silicon-based substance called aerogel, Stardust will capture comet particles flying off the nucleus of the comet. The spacecraft also will bring back samples of interstellar dust. These materials consist of ancient pre-solar interstellar grains and other remnants left over from the formation of the solar system. Scientists expect their analysis to provide important insights into the evolution of the sun and planets and possibly into the origin of life itself. The collected samples will return to Earth in a sample return capsule to be jettisoned as Stardust swings by Earth in January 2006.

  13. Structure of mega-hemocyanin reveals protein origami in snails.

    PubMed

    Gatsogiannis, Christos; Hofnagel, Oliver; Markl, Jürgen; Raunser, Stefan

    2015-01-01

    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. PMID:25482543

  14. What does physical rotation reveal about mental rotation?

    PubMed

    Gardony, Aaron L; Taylor, Holly A; Brunyé, Tad T

    2014-02-01

    In a classic psychological science experiment, Shepard and Metzler (1971) discovered that the time participants took to judge whether two rotated abstract block figures were identical increased monotonically with the figures' relative angular disparity. They posited that participants rotate mental images to achieve a match and that mental rotation recruits motor processes. This interpretation has become central in the literature, but until now, surprisingly few researchers have compared mental and physical rotation. We had participants rotate virtual Shepard and Metzler figures mentally and physically; response time, accuracy, and real-time rotation data were collected. Results suggest that mental and physical rotation processes overlap and also reveal novel conclusions about physical rotation that have implications for mental rotation. Notably, participants did not rotate figures to achieve a match, but rather until they reached an off-axis canonical difference, and rotational strategies markedly differed for judgments of whether the figures were the same or different.

  15. Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium

    PubMed Central

    Ma, Li-Jun; van der Does, H. Charlotte; Borkovich, Katherine A.; Coleman, Jeffrey J.; Daboussi, Marie-Josée; Di Pietro, Antonio; Dufresne, Marie; Freitag, Michael; Grabherr, Manfred; Henrissat, Bernard; Houterman, Petra M.; Kang, Seogchan; Shim, Won-Bo; Woloshuk, Charles; Xie, Xiaohui; Xu, Jin-Rong; Antoniw, John; Baker, Scott E.; Bluhm, Burton H.; Breakspear, Andrew; Brown, Daren W.; Butchko, Robert A. E.; Chapman, Sinead; Coulson, Richard; Coutinho, Pedro M.; Danchin, Etienne G. J.; Diener, Andrew; Gale, Liane R.; Gardiner, Donald M.; Goff, Stephen; Hammond-Kosack, Kim E.; Hilburn, Karen; Hua-Van, Aurélie; 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. Carmen; Sain, Divya; Sakthikumar, Sharadha; Sykes, Sean; Schwartz, David C.; Turgeon, B. Gillian; Wapinski, Ilan; Yoder, Olen; Young, Sarah; Zeng, Qiandong; Zhou, Shiguo; Galagan, James; Cuomo, Christina A.; Kistler, H. Corby; Rep, Martijn

    2011-01-01

    Fusarium species are among the most important phytopathogenic and toxigenic fungi. To understand the molecular underpinnings of pathogenicity in the genus Fusarium, we compared the genomes of three phenotypically diverse species: Fusarium graminearum, Fusarium verticillioides and Fusarium oxysporum f. sp. lycopersici. Our analysis revealed lineage-specific (LS) genomic regions in F. oxysporum that include four entire chromosomes and account for more than one-quarter of the genome. LS regions are rich in transposons and genes with distinct evolutionary profiles but related to pathogenicity, indicative of horizontal acquisition. Experimentally, we demonstrate the transfer of two LS chromosomes between strains of F. oxysporum, converting 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 F. oxysporum. These findings put the evolution of fungal pathogenicity into a new perspective. PMID:20237561

  16. 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.

  17. 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.

  18. Graph analysis of cortical networks reveals complex anatomical communication substrate

    NASA Astrophysics Data System (ADS)

    Zamora-López, Gorka; Zhou, Changsong; Kurths, Jürgen

    2009-03-01

    Sensory information entering the nervous system follows independent paths of processing such that specific features are individually detected. However, sensory perception, awareness, and cognition emerge from the combination of information. Here we have analyzed the corticocortical network of the cat, looking for the anatomical substrate which permits the simultaneous segregation and integration of information in the brain. We find that cortical communications are mainly governed by three topological factors of the underlying network: (i) a large density of connections, (ii) segregation of cortical areas into clusters, and (iii) the presence of highly connected hubs aiding the multisensory processing and integration. Statistical analysis of the shortest paths reveals that, while information is highly accessible to all cortical areas, the complexity of cortical information processing may arise from the rich and intricate alternative paths in which areas can influence each other.

  19. 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

  20. 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.

  1. 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

    2015-11-01

    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.

  2. Proteomic profiling reveals insights into Triticeae stigma development and function.

    PubMed

    Nazemof, Nazila; Couroux, Philippe; Rampitsch, Christof; Xing, Tim; Robert, Laurian S

    2014-11-01

    To our knowledge, this study represents the first high-throughput characterization of a stigma proteome in the Triticeae. A total of 2184 triticale mature stigma proteins were identified using three different gel-based approaches combined with mass spectrometry. The great majority of these proteins are described in a Triticeae stigma for the first time. These results revealed many proteins likely to play important roles in stigma development and pollen-stigma interactions, as well as protection against biotic and abiotic stresses. Quantitative comparison of the triticale stigma transcriptome and proteome showed poor correlation, highlighting the importance of having both types of analysis. This work makes a significant contribution towards the elucidation of the Triticeae stigma proteome and provides novel insights into its role in stigma development and function. PMID:25170101

  3. 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. PMID:26510689

  4. Deciphering CAPTCHAs: what a Turing test reveals about human cognition.

    PubMed

    Hannagan, Thomas; Ktori, Maria; Chanceaux, Myriam; Grainger, Jonathan

    2012-01-01

    Turning Turing's logic on its head, we used widespread letter-based Turing Tests found on the internet (CAPTCHAs) to shed light on human cognition. We examined the basis of the human ability to solve CAPTCHAs, where machines fail. We asked whether this is due to our use of slow-acting inferential processes that would not be available to machines, or whether fast-acting automatic orthographic processing in humans has superior robustness to shape variations. A masked priming lexical decision experiment revealed efficient processing of CAPTCHA words in conditions that rule out the use of slow inferential processing. This shows that the human superiority in solving CAPTCHAs builds on a high degree of invariance to location and continuous transforms, which is achieved during the very early stages of visual word recognition in skilled readers.

  5. Dramatic changes in electronic structure revealed by fractionally charged nuclei

    SciTech Connect

    Cohen, Aron J.; Mori-Sánchez, Paula

    2014-01-28

    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.

  6. Revealing the superior perceptibility of words in Arabic.

    PubMed

    Jordan, Timothy R; Paterson, Kevin B; Almabruk, Abubaker A A

    2010-01-01

    When alphabetic stimuli are presented very briefly, people perceive real words better than nonwords. It is generally accepted that this word superiority effect reflects the efficiency of visual word perception. However, much of what is known about this effect comes from research conducted in languages using the Latin alphabet (eg English, French, Italian), and little is known about whether alphabetic languages with visual properties fundamentally different from Latinate languages also produce word superiority effects. We report an experiment in which stimuli (words, illegal nonwords, and pseudowords) were presented in Arabic, which is a cursive script, read from right to left. The findings revealed advantages for words over pseudowords and illegal nonwords, and for pseudowords over illegal nonwords, indicating that the superiority effects reported for Latinate languages are also observed in Arabic. Implications of these findings for understanding the processes involved in word recognition are discussed. PMID:20465177

  7. Freshwater foraminiferans revealed by analysis of environmental DNA samples.

    PubMed

    Holzmann, Maria; Habura, Andrea; Giles, Hannah; Bowser, Samuel S; Pawlowski, Jan

    2003-01-01

    Sediment-dwelling protists are among the most abundant meiobenthic organisms, ubiquitous in all types of aquatic ecosystems. Yet, because their isolation and identification are difficult, their diversity remains largely unknown. In the present work, we applied molecular methods to examine the diversity of freshwater Foraminifera, a group of granuloreticulosan protists largely neglected until now. By using specific PCR primers, we detected the presence of Foraminifera in all sediment samples examined. Phylogenetic analysis of amplified SSU rDNA sequences revealed two distinct groups of freshwater foraminiferans. All obtained sequences branched within monothalamous (single-chambered), marine Foraminifera, suggesting a repeated colonization of freshwater environments. The results of our study challenge the traditional view of Foraminifera as essentially marine organisms, and provide a conceptual framework for charting the molecular diversity of freshwater granuloreticulosan protists.

  8. 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

  9. Collagenous gastritis revealed by severe anemia in a child.

    PubMed

    Côté, J F; Hankard, G F; Faure, C; Mougenot, J F; Holvoet, L; Cézard, J P; Navarro, J; Peuchmaur, M

    1998-08-01

    Collagenous gastritis is a rare histopathological disorder of unknown origin, characterized by a subepithelial collagen deposit greater than 10 microm thick, associated with an inflammatory infiltrate of the gastric mucosa. This report describes a second pediatric case of collagenous gastritis, revealed by severe anemia caused by gastric bleeding, as was the first case. Unlike the adult cases of collagenous gastritis, lesions were limited to the stomach, and remained unchanged on six series of biopsies taken during a 30 month follow-up, despite treatment with omeprazole, sucralfate and corticosteroids. An immunohistochemical study showed signs of local immune activation on all biopsy specimens, including overexpression of HLA-DR by epithelial cells, increased numbers of CD3+ intraepithelial lymphocytes, and CD25+ cells in the lamina propria. Although the cause of the disease remains unclear, our findings suggest that the histopathological lesions of collagenous gastritis may result from a local immune process. PMID:9712433

  10. Ternary structure reveals mechanism of a membrane diacylglycerol kinase.

    PubMed

    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. The active site architecture shows clear evidence of having arisen by convergent evolution.

  11. 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.

  12. 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

    2015-11-01

    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. PMID:26542579

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. Coupled nucleotide covariations reveal dynamic RNA interaction patterns.

    PubMed Central

    Gultyaev, A P; Franch, T; Gerdes, K

    2000-01-01

    Evolutionarily conserved structures in related RNA molecules contain coordinated variations (covariations) of paired nucleotides. Analysis of covariations is a very powerful approach to deduce phylogenetically conserved (i.e., functional) conformations, including tertiary interactions. Here we discuss conserved RNA folding pathways that are revealed by covariation patterns. In such pathways, structural requirements for alternative pairings cause some nucleotides to covary with two different partners. Such "coupled" covariations between three or more nucleotides were found in various types of RNAs. The analysis of coupled covariations can unravel important features of RNA folding dynamics and improve phylogeny reconstruction in some cases. Importantly, it is necessary to distinguish between multiple covariations determined by mutually exclusive structures and those determined by tertiary contacts. PMID:11105748

  18. Ternary structure reveals mechanism of a membrane diacylglycerol kinase.

    PubMed

    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

  19. An alternative RNA polymerase I structure reveals a dimer hinge.

    PubMed

    Kostrewa, Dirk; Kuhn, Claus-D; Engel, Christoph; Cramer, Patrick

    2015-09-01

    RNA polymerase I (Pol I) is the central, 14-subunit enzyme that synthesizes the ribosomal RNA (rRNA) precursor in eukaryotic cells. The recent crystal structure of Pol I at 2.8 Å resolution revealed two novel elements: the `expander' in the active-centre cleft and the `connector' that mediates Pol I dimerization [Engel et al. (2013), Nature (London), 502, 650-655]. Here, a Pol I structure in an alternative crystal form that was solved by molecular replacement using the original atomic Pol I structure is reported. The resulting alternative structure lacks the expander but still shows an expanded active-centre cleft. The neighbouring Pol I monomers form a homodimer with a relative orientation distinct from that observed previously, establishing the connector as a hinge between Pol I monomers.

  20. 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

  1. Four not six: Revealing culturally common facial expressions of emotion.

    PubMed

    Jack, Rachael E; Sun, Wei; Delis, Ioannis; Garrod, Oliver G B; Schyns, Philippe G

    2016-06-01

    As a highly social species, humans generate complex facial expressions to communicate a diverse range of emotions. Since Darwin's work, identifying among these complex patterns which are common across cultures and which are culture-specific has remained a central question in psychology, anthropology, philosophy, and more recently machine vision and social robotics. Classic approaches to addressing this question typically tested the cross-cultural recognition of theoretically motivated facial expressions representing 6 emotions, and reported universality. Yet, variable recognition accuracy across cultures suggests a narrower cross-cultural communication supported by sets of simpler expressive patterns embedded in more complex facial expressions. We explore this hypothesis by modeling the facial expressions of over 60 emotions across 2 cultures, and segregating out the latent expressive patterns. Using a multidisciplinary approach, we first map the conceptual organization of a broad spectrum of emotion words by building semantic networks in 2 cultures. For each emotion word in each culture, we then model and validate its corresponding dynamic facial expression, producing over 60 culturally valid facial expression models. We then apply to the pooled models a multivariate data reduction technique, revealing 4 latent and culturally common facial expression patterns that each communicates specific combinations of valence, arousal, and dominance. We then reveal the face movements that accentuate each latent expressive pattern to create complex facial expressions. Our data questions the widely held view that 6 facial expression patterns are universal, instead suggesting 4 latent expressive patterns with direct implications for emotion communication, social psychology, cognitive neuroscience, and social robotics. (PsycINFO Database Record PMID:27077757

  2. 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

  3. Four not six: Revealing culturally common facial expressions of emotion.

    PubMed

    Jack, Rachael E; Sun, Wei; Delis, Ioannis; Garrod, Oliver G B; Schyns, Philippe G

    2016-06-01

    As a highly social species, humans generate complex facial expressions to communicate a diverse range of emotions. Since Darwin's work, identifying among these complex patterns which are common across cultures and which are culture-specific has remained a central question in psychology, anthropology, philosophy, and more recently machine vision and social robotics. Classic approaches to addressing this question typically tested the cross-cultural recognition of theoretically motivated facial expressions representing 6 emotions, and reported universality. Yet, variable recognition accuracy across cultures suggests a narrower cross-cultural communication supported by sets of simpler expressive patterns embedded in more complex facial expressions. We explore this hypothesis by modeling the facial expressions of over 60 emotions across 2 cultures, and segregating out the latent expressive patterns. Using a multidisciplinary approach, we first map the conceptual organization of a broad spectrum of emotion words by building semantic networks in 2 cultures. For each emotion word in each culture, we then model and validate its corresponding dynamic facial expression, producing over 60 culturally valid facial expression models. We then apply to the pooled models a multivariate data reduction technique, revealing 4 latent and culturally common facial expression patterns that each communicates specific combinations of valence, arousal, and dominance. We then reveal the face movements that accentuate each latent expressive pattern to create complex facial expressions. Our data questions the widely held view that 6 facial expression patterns are universal, instead suggesting 4 latent expressive patterns with direct implications for emotion communication, social psychology, cognitive neuroscience, and social robotics. (PsycINFO Database Record

  4. 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

  5. Running over rough terrain reveals limb control for intrinsic stability

    PubMed Central

    Daley, Monica A.; Biewener, Andrew A.

    2006-01-01

    Legged animals routinely negotiate rough, unpredictable terrain with agility and stability that outmatches any human-built machine. Yet, we know surprisingly little about how animals accomplish this. Current knowledge is largely limited to studies of steady movement. These studies have revealed fundamental mechanisms used by terrestrial animals for steady locomotion. However, it is unclear whether these models provide an appropriate framework for the neuromuscular and mechanical strategies used to achieve dynamic stability over rough terrain. Perturbation experiments shed light on this issue, revealing the interplay between mechanics and neuromuscular control. We measured limb mechanics of helmeted guinea fowl (Numida meleagris) running over an unexpected drop in terrain, comparing their response to predictions of the mass–spring running model. Adjustment of limb contact angle explains 80% of the variation in stance-phase limb loading following the perturbation. Surprisingly, although limb stiffness varies dramatically, it does not influence the response. This result agrees with a mass–spring model, although it differs from previous findings on humans running over surfaces of varying compliance. However, guinea fowl sometimes deviate from mass–spring dynamics through posture-dependent work performance of the limb, leading to substantial energy absorption following the perturbation. This posture-dependent actuation allows the animal to absorb energy and maintain desired velocity on a sudden substrate drop. Thus, posture-dependent work performance of the limb provides inherent velocity control over rough terrain. These findings highlight how simple mechanical models extend to unsteady conditions, providing fundamental insights into neuromuscular control of movement and the design of dynamically stable legged robots and prosthetic devices. PMID:17032779

  6. 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.

  7. Ethiopian Population Dermatoglyphic Study Reveals Linguistic Stratification of Diversity

    PubMed Central

    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

  8. 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

  9. Compartmentation of glycogen metabolism revealed from 13C isotopologue distributions

    PubMed Central

    2011-01-01

    Background Stable isotope tracers are used to assess metabolic flux profiles in living cells. The existing methods of measurement average out the isotopic isomer distribution in metabolites throughout the cell, whereas the knowledge of compartmental organization of analyzed pathways is crucial for the evaluation of true fluxes. That is why we accepted a challenge to create a software tool that allows deciphering the compartmentation of metabolites based on the analysis of average isotopic isomer distribution. Results The software Isodyn, which simulates the dynamics of isotopic isomer distribution in central metabolic pathways, was supplemented by algorithms facilitating the transition between various analyzed metabolic schemes, and by the tools for model discrimination. It simulated 13C isotope distributions in glucose, lactate, glutamate and glycogen, measured by mass spectrometry after incubation of hepatocytes in the presence of only labeled glucose or glucose and lactate together (with label either in glucose or lactate). The simulations assumed either a single intracellular hexose phosphate pool, or also channeling of hexose phosphates resulting in a different isotopic composition of glycogen. Model discrimination test was applied to check the consistency of both models with experimental data. Metabolic flux profiles, evaluated with the accepted model that assumes channeling, revealed the range of changes in metabolic fluxes in liver cells. Conclusions The analysis of compartmentation of metabolic networks based on the measured 13C distribution was included in Isodyn as a routine procedure. The advantage of this implementation is that, being a part of evaluation of metabolic fluxes, it does not require additional experiments to study metabolic compartmentation. The analysis of experimental data revealed that the distribution of measured 13C-labeled glucose metabolites is inconsistent with the idea of perfect mixing of hexose phosphates in cytosol. In contrast

  10. Mineralization of developing mouse calvaria as revealed by Raman microspectroscopy.

    PubMed

    Tarnowski, Catherine P; Ignelzi, Michael A; Morris, Michael D

    2002-06-01

    Raman microspectroscopy is a nondestructive vibrational spectroscopic technique that permits the study of organic and mineral species at micron resolution, offers the ability to work with hydrated and dehydrated specimens in vivo or in vitro, and requires minimal specimen preparation. We used Raman microspectroscopy to determine the composition of the mineral environments present in mouse calvaria, the flat bones that comprise the top of the skull. We have acquired Raman transects (lines of point spectra) from mouse calvaria during a developmental time course ranging from embryonic day 13.5 (E13.5; 6 days before birth) to 6 months of age. Exploratory factor analysis (FA) reveals the presence of a variety of apatitic mineral environments throughout the tissue series. The earliest mineral is observed in the fetal day 15.5 (F15.5) mice and is identified as a carbonated apatite. The presence of a heterogeneous mineralized tissue in the postnatal specimens suggests that ionic incorporation and crystal perfection in the lattice yary as the mouse develops. This variation is indicative of the presence of both recently deposited mineral and more matured remodeled mineral. Band area ratios reveal that the mineral/matrix ratio initially increases, reaches a plateau, and then increases again. The carbonate/phosphate band area ratio remains constant from F18.5 to postnatal day 3 (PN3) and then increases with age. Insights into the chemical species, the degree of mineralization, and the multiple mineral environments that are present in normal calvarial tissue will enable us to better understand both normal and abnormal mineralization processes.

  11. Antibody protection reveals extended epitopes on the human TSH receptor.

    PubMed

    Latif, Rauf; Teixeira, Avelino; Michalek, Krzysztof; Ali, M Rejwan; Schlesinger, Max; Baliram, Ramkumarie; Morshed, Syed A; Davies, Terry F

    2012-01-01

    Stimulating, and some blocking, antibodies to the TSH receptor (TSHR) have conformation-dependent epitopes reported to involve primarily the leucine rich repeat region of the ectodomain (LRD). However, successful crystallization of TSHR residues 22-260 has omitted important extracellular non-LRD residues including the hinge region which connects the TSHR ectodomain to the transmembrane domain and which is involved in ligand induced signal transduction. The aim of the present study, therefore, was to determine if TSHR antibodies (TSHR-Abs) have non-LRD binding sites outside the LRD. To obtain this information we employed the method of epitope protection in which we first protected TSHR residues 1-412 with intact TSHR antibodies and then enzymatically digested the unprotected residues. Those peptides remaining were subsequently delineated by mass spectrometry. Fourteen out of 23 of the reported stimulating monoclonal TSHR-Ab crystal contact residues were protected by this technique which may reflect the higher binding energies of certain residues detected in this approach. Comparing the protected epitopes of two stimulating TSHR-Abs we found both similarities and differences but both antibodies also contacted the hinge region and the amino terminus of the TSHR following the signal peptide and encompassing cysteine box 1 which has previously been shown to be important for TSH binding and activation. A monoclonal blocking TSHR antibody revealed a similar pattern of binding regions but the residues that it contacted on the LRD were again distinct. These data demonstrated that conformationally dependent TSHR-Abs had epitopes not confined to the LRDs but also incorporated epitopes not revealed in the available crystal structure. Furthermore, the data also indicated that in addition to overlapping contact regions within the LRD, there are unique epitope patterns for each of the antibodies which may contribute to their functional heterogeneity. PMID:22957097

  12. Astronomers Reveal Extinct Extra-Terrestrial Fusion Reactor

    NASA Astrophysics Data System (ADS)

    2004-06-01

    An international team of astronomers, studying the left-over remnants of stars like our own Sun, have found a remarkable object where the nuclear reactor that once powered it has only just shut down. This star, the hottest known white dwarf, H1504+65, seems to have been stripped of its entire outer regions during its death throes leaving behind the core that formed its power plant. Scientists from the United Kingdom, Germany and the USA focused two of NASA's space telescopes, the Chandra X-ray Observatory and the Far Ultraviolet Spectroscopic Explorer (FUSE), onto H1504+65 to probe its composition and measure its temperature. The data revealed that the stellar surface is extremely hot, 200,000 degrees, and is virtually free of hydrogen and helium, something never before observed in any star. Instead, the surface is composed mainly of carbon and oxygen, the 'ashes' of the fusion of helium in a nuclear reactor. An important question we must answer is why has this unique star lost the hydrogen and helium, which usually hide the stellar interior from our view? Professor Martin Barstow (University of Leicester) said. 'Studying the nature of the ashes of dead stars give us important clues as to how stars like the Sun live their lives and eventually die. The nuclear waste of carbon and oxygen produced in the process are essential elements for life and are eventually recycled into interstellar space to form new stars, planets and, possibly, living beings.' Professor Klaus Werner (University of Tübingen) said. 'We realized that this star has, on astronomical time scales, only very recently shut down nuclear fusion (about a hundred years ago). We clearly see the bare, now extinct reactor that once powered a bright giant star.' Dr Jeffrey Kruk (Johns Hopkins University) said: 'Astronomers have long predicted that many stars would have carbon-oxygen cores near the end of their lives, but I never expected we would actually be able to see one. This is a wonderful opportunity to

  13. 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

    2014-01-01

    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

  14. 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

  15. 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

    2014-01-01

    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

  16. Diagnostic phylogenetics reveals a new Porcine circovirus 2 cluster.

    PubMed

    Davies, Brendan; Wang, Xiong; Dvorak, Cheryl M T; Marthaler, Douglas; Murtaugh, Michael P

    2016-06-01

    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. PMID:26948261

  17. 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.

  18. 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

  19. Perceptual rivalry: reflexes reveal the gradual nature of visual awareness.

    PubMed

    Naber, Marnix; Frässle, Stefan; Einhäuser, Wolfgang

    2011-01-01

    Rivalry is a common tool to probe visual awareness: a constant physical stimulus evokes multiple, distinct perceptual interpretations ("percepts") that alternate over time. Percepts are typically described as mutually exclusive, suggesting that a discrete (all-or-none) process underlies changes in visual awareness. Here we follow two strategies to address whether rivalry is an all-or-none process: first, we introduce two reflexes as objective measures of rivalry, pupil dilation and optokinetic nystagmus (OKN); second, we use a continuous input device (analog joystick) to allow observers a gradual subjective report. We find that the "reflexes" reflect the percept rather than the physical stimulus. Both reflexes show a gradual dependence on the time relative to perceptual transitions. Similarly, observers' joystick deflections, which are highly correlated with the reflex measures, indicate gradual transitions. Physically simulating wave-like transitions between percepts suggest piece-meal rivalry (i.e., different regions of space belonging to distinct percepts) as one possible explanation for the gradual transitions. Furthermore, the reflexes show that dominance durations depend on whether or not the percept is actively reported. In addition, reflexes respond to transitions with shorter latencies than the subjective report and show an abundance of short dominance durations. This failure to report fast changes in dominance may result from limited access of introspection to rivalry dynamics. In sum, reflexes reveal that rivalry is a gradual process, rivalry's dynamics is modulated by the required action (response mode), and that rapid transitions in perceptual dominance can slip away from awareness. PMID:21677786

  20. Candida milleri species reveals intraspecific genetic and metabolic polymorphisms.

    PubMed

    Vigentini, Ileana; Antoniani, Davide; Roscini, Luca; Comasio, Andrea; Galafassi, Silvia; Picozzi, Claudia; Corte, Laura; Compagno, Concetta; Dal Bello, Fabio; Cardinali, Gianluigi; Foschino, Roberto

    2014-09-01

    Candida milleri, together with Candida humilis, is the most representative yeast species found in type I sourdough ecosystems. In this work, comparison of the ITS region and the D1/D2 domain of 26S rDNA gene partial sequences, karyotyping, mtDNA-RFLP analysis, Intron Splice Site dispersion (ISS-PCR) and (GTG)5 microsatellite analyses, assimilation test of different carbohydrates, and metabolome assessment by FT-IR analysis, were investigated in seventeen strains isolated from four different companies as well as in type strains CBS6897(T) and CBS5658(T). Most isolates were ascribed to C. milleri, even if a strong relatedness was confirmed with C. humilis as well, particularly for three strains. Genetic characterization showed a high degree of intraspecific polymorphism since 12 different genotypes were discriminated. The number of chromosomes varied from 9 to 13 and their size ranged from less than 0.3 to over 2 Mbp. Phenotypic traits let to recognize 9 different profiles of carbon sources assimilation. FT-IR spectra from yeast cells cultivated in different media and collected at different growth phases revealed a diversity of behaviour among strains in accordance with the results of PCR-based fingerprinting. A clear evidence of the polymorphic status of C. milleri species is provided thus representing an important feature for the development of technological applications in bakery industries.

  1. Sparse expression bases in cancer reveal tumor drivers.

    PubMed

    Logsdon, Benjamin A; Gentles, Andrew J; Miller, Chris P; Blau, C Anthony; Becker, Pamela S; Lee, Su-In

    2015-02-18

    We define a new category of candidate tumor drivers in cancer genome evolution: 'selected expression regulators' (SERs)-genes driving dysregulated transcriptional programs in cancer evolution. The SERs are identified from genome-wide tumor expression data with a novel method, namely SPARROW ( SPAR: se selected exp R: essi O: n regulators identified W: ith penalized regression). SPARROW uncovers a previously unknown connection between cancer expression variation and driver events, by using a novel sparse regression technique. Our results indicate that SPARROW is a powerful complementary approach to identify candidate genes containing driver events that are hard to detect from sequence data, due to a large number of passenger mutations and lack of comprehensive sequence information from a sufficiently large number of samples. SERs identified by SPARROW reveal known driver mutations in multiple human cancers, along with known cancer-associated processes and survival-associated genes, better than popular methods for inferring gene expression networks. We demonstrate that when applied to acute myeloid leukemia expression data, SPARROW identifies an apoptotic biomarker (PYCARD) for an investigational drug obatoclax. The PYCARD and obatoclax association is validated in 30 AML patient samples.

  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. Early Neolithic water wells reveal the world's oldest wood architecture.

    PubMed

    Tegel, Willy; Elburg, Rengert; Hakelberg, Dietrich; Stäuble, Harald; Büntgen, Ulf

    2012-01-01

    The European Neolithization ~6000-4000 BC represents a pivotal change in human history when farming spread and the mobile style of life of the hunter-foragers was superseded by the agrarian culture. Permanent settlement structures and agricultural production systems required fundamental innovations in technology, subsistence, and resource utilization. Motivation, course, and timing of this transformation, however, remain debatable. Here we present annually resolved and absolutely dated dendroarchaeological information from four wooden water wells of the early Neolithic period that were excavated in Eastern Germany. A total of 151 oak timbers preserved in a waterlogged environment were dated between 5469 and 5098 BC and reveal unexpectedly refined carpentry skills. The recently discovered water wells enable for the first time a detailed insight into the earliest wood architecture and display the technological capabilities of humans ~7000 years ago. The timbered well constructions made of old oak trees feature an unopened tree-ring archive from which annually resolved and absolutely dated environmental data can be culled. Our results question the principle of continuous evolutionary development in prehistoric technology, and contradict the common belief that metal was necessary for complex timber constructions. Early Neolithic craftsmanship now suggests that the first farmers were also the first carpenters. PMID:23284685

  4. Integrative network analysis reveals molecular mechanisms of blood pressure regulation.

    PubMed

    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.

  5. Integrative network analysis reveals molecular mechanisms of blood pressure regulation.

    PubMed

    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

    2015-04-01

    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.

  6. Transcriptome profiling reveals mosaic genomic origins of modern cultivated barley.

    PubMed

    Dai, Fei; Chen, Zhong-Hua; Wang, Xiaolei; Li, Zefeng; Jin, Gulei; Wu, Dezhi; Cai, Shengguan; Wang, Ning; Wu, Feibo; Nevo, Eviatar; Zhang, Guoping

    2014-09-16

    The domestication of cultivated barley has been used as a model system for studying the origins and early spread of agrarian culture. Our previous results indicated that the Tibetan Plateau and its vicinity is one of the centers of domestication of cultivated barley. Here we reveal multiple origins of domesticated barley using transcriptome profiling of cultivated and wild-barley genotypes. Approximately 48-Gb of clean transcript sequences in 12 Hordeum spontaneum and 9 Hordeum vulgare accessions were generated. We reported 12,530 de novo assembled transcripts in all of the 21 samples. Population structure analysis showed that Tibetan hulless barley (qingke) might have existed in the early stage of domestication. Based on the large number of unique genomic regions showing the similarity between cultivated and wild-barley groups, we propose that the genomic origin of modern cultivated barley is derived from wild-barley genotypes in the Fertile Crescent (mainly in chromosomes 1H, 2H, and 3H) and Tibet (mainly in chromosomes 4H, 5H, 6H, and 7H). This study indicates that the domestication of barley may have occurred over time in geographically distinct regions. PMID:25197090

  7. Jamming Criticality Revealed by Removing Localized Buckling Excitations

    NASA Astrophysics Data System (ADS)

    Charbonneau, Patrick; Corwin, Eric I.; Parisi, Giorgio; Zamponi, Francesco

    2015-03-01

    Recent theoretical advances offer an exact, first-principles theory of jamming criticality in infinite dimension as well as universal scaling relations between critical exponents in all dimensions. For packings of frictionless spheres near the jamming transition, these advances predict that nontrivial power-law exponents characterize the critical distribution of (i) small interparticle gaps and (ii) weak contact forces, both of which are crucial for mechanical stability. The scaling of the interparticle gaps is known to be constant in all spatial dimensions d —including the physically relevant d =2 and 3, but the value of the weak force exponent remains the object of debate and confusion. Here, we resolve this ambiguity by numerical simulations. We construct isostatic jammed packings with extremely high accuracy, and introduce a simple criterion to separate the contribution of particles that give rise to localized buckling excitations, i.e., bucklers, from the others. This analysis reveals the remarkable dimensional robustness of mean-field marginality and its associated criticality.

  8. 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

  9. Beyond Contagion: Reality Mining Reveals Complex Patterns of Social Influence

    PubMed Central

    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. PMID:26313449

  10. Structure of the Angiotensin receptor revealed by serial femtosecond crystallography.

    PubMed

    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

    2015-05-01

    Angiotensin II type 1 receptor (AT(1)R) 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 AT(1)R blockers (ARBs), the structural basis for AT(1)R 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 AT(1)R in complex with its selective antagonist ZD7155 at 2.9-Å resolution. The AT(1)R-ZD7155 complex structure revealed key structural features of AT(1)R and critical interactions for ZD7155 binding. Docking simulations of the clinically used ARBs into the AT(1)R structure further elucidated both the common and distinct binding modes for these anti-hypertensive drugs. Our results thereby provide fundamental insights into AT(1)R structure-function relationship and structure-based drug design.

  11. Quantification of the stapedial reflex reveals delayed responses in autism.

    PubMed

    Lukose, Richard; Brown, Kevin; Barber, Carol M; Kulesza, Randy Joseph

    2013-10-01

    Autism is a developmental disorder characterized, in part, by sensory abnormalities. It is well established that most if not all patients with autism have problems with auditory processing, ranging from deafness to hyperacusis, and physiological testing of auditory function (i.e. auditory brain stem responses) implicates brain stem dysfunction in autism. Additionally, previous research from this lab has revealed significantly fewer auditory brain stem neurons in autistic subjects as young as 2 years of age. These observations have led us to hypothesize that objective, noninvasive measures of auditory function can be used as an early screening tool to identify neonates with an elevated risk of carrying a diagnosis of autism. Here, we provide a detailed quantitative investigation of the acoustic stapedial reflex (ASR), a three- or four-neuron brain stem circuit, in young autistic subjects and normal developing controls. Indeed, we find significantly lower thresholds, responses occurring at significantly longer latency and right-left asymmetry in autistic subjects. The results from this investigation support deficits in auditory function as a cardinal feature of autism and suggest that individuals with autism can be identified by their ASR responses. PMID:23825093

  12. Temperature-cycle microscopy reveals single-molecule conformational heterogeneity.

    PubMed

    Yuan, Haifeng; Gaiduk, Alexander; Siekierzycka, Joanna R; Fujiyoshi, Satoru; Matsushita, Michio; Nettels, Daniel; Schuler, Benjamin; Seidel, Claus A M; Orrit, Michel

    2015-03-01

    Our previous temperature-cycle study reported FRET transitions between different states on FRET-labeled polyprolines [Yuan et al., PCCP, 2011, 13, 1762]. The conformational origin of such transitions, however, was left open. In this work, we apply temperature-cycle microscopy of single FRET-labeled polyproline and dsDNA molecules and compare their responses to resolve the conformational origin of different FRET states. We observe different steady-state FRET distributions and different temperature-cycle responses in the two samples. Our temperature-cycle results on single molecules resemble the results in steady-state measurements but reveal a dark state which could not be observed otherwise. By comparing the timescales and probabilities of different FRET states in temperature-cycle traces, we assign the conformational heterogeneity reflected by different FRET states to linker dynamics, dye-chain and dye-dye interactions. The dark state and low-FRET state are likely due to dye-dye interactions at short separations.

  13. 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.

  14. 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.

  15. Global isotope metabolomics reveals adaptive strategies for nitrogen assimilation

    DOE PAGESBeta

    Kurczy, Michael E.; Forsberg, Erica M.; Thorgersen, Michael P.; Poole, Farris L.; Benton, H. Paul; Ivanisevic, Julijana; Tran, Minerva L.; Wall, Judy D.; Elias, Dwayne A.; Adams, Michael W. W.; et al

    2016-04-05

    Nitrogen cycling is a microbial metabolic process essential for global ecological/agricultural balance. To investigate the link between the well-established ammonium and the alternative nitrate assimilation metabolic pathways, global isotope metabolomics was employed to examine three nitrate reducing bacteria using 15NO3 as a nitrogen source. In contrast to a control (Pseudomonas stutzeri RCH2), the results show that two of the isolates from Oak Ridge, Tennessee (Pseudomonas N2A2 and N2E2) utilize nitrate and ammonia for assimilation concurrently with differential labeling observed across multiple classes of metabolites including amino acids and nucleotides. The data reveal that the N2A2 and N2E2 strains conserve nitrogen-containingmore » metabolites, indicating that the nitrate assimilation pathway is a conservation mechanism for the assimilation of nitrogen. Co-utilization of nitrate and ammonia is likely an adaption to manage higher levels of nitrite since the denitrification pathways utilized by the N2A2 and N2E2 strains from the Oak Ridge site are predisposed to the accumulation of the toxic nitrite. In conclusion, the use of global isotope metabolomics allowed for this adaptive strategy to be investigated, which would otherwise not have been possible to decipher.« less

  16. Identification of disulfide bond isomerase substrates reveals bacterial virulence factors

    PubMed Central

    Ren, Guoping; Champion, Matthew M.; Huntley, Jason F.

    2014-01-01

    Summary Bacterial pathogens are exposed to toxic molecules inside the host and require efficient systems to form and maintain correct disulfide bonds for protein stability and function. The intracellular pathogen Francisella tularensis encodes a disulfide bond formation protein ortholog, DsbA, which previously was reported to be required for infection of macrophages and mice. However, the molecular mechanisms by which F. tularensis DsbA contributes to virulence are unknown. Here, we demonstrate that F. tularensis DsbA is a bifunctional protein that oxidizes and, more importantly, isomerizes complex disulfide connectivity in substrates. A single amino acid in the conserved cis-proline loop of the DsbA thioredoxin domain was shown to modulate both isomerase activity and F. tularensis virulence. Trapping experiments in F. tularensis identified over 50 F. tularensis DsbA substrates, including outer membrane proteins, virulence factors, and many hypothetical proteins. Six of these hypothetical proteins were randomly selected and deleted, revealing two novel proteins, FTL_1548 and FTL_1709, which are required for F. tularensis virulence. We propose that the extreme virulence of F. tularensis is partially due to the bifunctional nature of DsbA, that many of the newly-identified substrates are required for virulence, and that the development of future DsbA inhibitors could have broad anti-bacterial implications. PMID:25257164

  17. Next generation sequencing in synovial sarcoma reveals novel gene mutations

    PubMed Central

    Vlenterie, Myrella; Hillebrandt-Roeffen, Melissa H.S.; Flucke, Uta E.; Groenen, Patricia J.T.A.; Tops, Bastiaan B.J.; Kamping, Eveline J.; Pfundt, Rolph; de Bruijn, Diederik R.H.; van Kessel, Ad H.M. Geurts; van Krieken, Han J.H.J.M.; van der Graaf, Winette T.A.; Versleijen-Jonkers, Yvonne M.H.

    2015-01-01

    Over 95% of all synovial sarcomas (SS) share a unique translocation, t(X;18), however, they show heterogeneous clinical behavior. We analyzed multiple SS to reveal additional genetic alterations besides the translocation. Twenty-six SS from 22 patients were sequenced for 409 cancer-related genes using the Comprehensive Cancer Panel (Life Technologies, USA) on an Ion Torrent platform. The detected variants were verified by Sanger sequencing and compared to matched normal DNAs. Copy number variation was assessed in six tumors using the Oncoscan array (Affymetrix, USA). In total, eight somatic mutations were detected in eight samples. These mutations have not been reported previously in SS. Two of these, in KRAS and CCND1, represent known oncogenic mutations in other malignancies. Additional mutations were detected in RNF213, SEPT9, KDR, CSMD3, MLH1 and ERBB4. DNA alterations occurred more often in adult tumors. A distinctive loss of 6q was found in a metastatic lesion progressing under pazopanib, but not in the responding lesion. Our results emphasize t(X;18) as a single initiating event in SS and as the main oncogenic driver. Our results also show the occurrence of additional genetic events, mutations or chromosomal aberrations, occurring more frequently in SS with an onset in adults. PMID:26415226

  18. 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.

  19. 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.

  20. 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. PMID:25210972

  1. Sparse expression bases in cancer reveal tumor drivers

    PubMed Central

    Logsdon, Benjamin A.; Gentles, Andrew J.; Miller, Chris P.; Blau, C. Anthony; Becker, Pamela S.; Lee, Su-In

    2015-01-01

    We define a new category of candidate tumor drivers in cancer genome evolution: ‘selected expression regulators’ (SERs)—genes driving dysregulated transcriptional programs in cancer evolution. The SERs are identified from genome-wide tumor expression data with a novel method, namely SPARROW (SPARse selected expRessiOn regulators identified With penalized regression). SPARROW uncovers a previously unknown connection between cancer expression variation and driver events, by using a novel sparse regression technique. Our results indicate that SPARROW is a powerful complementary approach to identify candidate genes containing driver events that are hard to detect from sequence data, due to a large number of passenger mutations and lack of comprehensive sequence information from a sufficiently large number of samples. SERs identified by SPARROW reveal known driver mutations in multiple human cancers, along with known cancer-associated processes and survival-associated genes, better than popular methods for inferring gene expression networks. We demonstrate that when applied to acute myeloid leukemia expression data, SPARROW identifies an apoptotic biomarker (PYCARD) for an investigational drug obatoclax. The PYCARD and obatoclax association is validated in 30 AML patient samples. PMID:25583238

  2. Pyrosequencing Reveals Fungal Communities in the Rhizosphere of Xinjiang Jujube

    PubMed Central

    Wang, Xiao-Hui; Li, Jian-Gui; Qin, Wei; Xiao, Cheng-Ze; Zhao, Xu; Jiang, Hong-Xia; Sui, Jun-Kang; Sa, Rong-Bo; Wang, Wei-Yan; Liu, Xun-Li

    2015-01-01

    Fungi are important soil components as both decomposers and plant symbionts and play a major role in ecological and biogeochemical processes. However, little is known about the richness and structure of fungal communities. DNA sequencing technologies allow for the direct estimation of microbial community diversity, avoiding culture-based biases. We therefore used 454 pyrosequencing to investigate the fungal communities in the rhizosphere of Xinjiang jujube. We obtained no less than 40,488 internal transcribed spacer (ITS) rDNA reads, the number of each sample was 6943, 6647, 6584, 6550, 6860, and 6904, and we used bioinformatics and multivariate statistics to analyze the results. The index of diversity showed greater richness in the rhizosphere fungal community of a 3-year-old jujube than in that of an 8-year-old jujube. Most operational taxonomic units belonged to Ascomycota, and taxonomic analyses identified Hypocreales as the dominant fungal order. Our results demonstrated that the fungal orders are present in different proportions in different sampling areas. Redundancy analysis (RDA) revealed a significant correlation between soil properties and the abundance of fungal phyla. Our results indicated lower fungal diversity in the rhizosphere of Xinjiang jujube than that reported in other studies, and we hope our findings provide a reference for future research. PMID:25685820

  3. Network deconstruction reveals network structure in responsive microgels.

    PubMed

    Smith, Michael H; Herman, Emily S; Lyon, L Andrew

    2011-04-14

    Detailed characterization of hydrogel particle erosion revealed critical physicochemical differences between spheres, where network decomposition was informative of network structure. Real-time, in situ monitoring of the triggered erosion of colloidal hydrogels (microgels) was performed via multiangle light scattering. The solution-average molar mass and root-mean-square radii of eroding particles were measured as a function of time for microgels prepared from N-isopropylacrylamide (NIPAm) or N-isopropylmethacrylamide (NIPMAm), copolymerized with a chemically labile cross-linker (1,2-dihydroxylethylene)bisacrylamide (DHEA). Precipitation polymerization was employed to yield particles of comparable dimensions but with distinct topological features. Heterogeneous cross-linker incorporation resulted in a heterogeneous network structure for pNIPAm microgels. During the erosion reaction, mass loss proceeded from the exterior toward the interior of the polymer. In contrast, pNIPMAm microgels had a more homogeneous network structure, which resulted in a more uniform mass loss throughout the particle during erosion. Although both particle types degraded into low molar mass products, pNIPAm microgels were incapable of complete dissolution due to the presence of nondegradable cross-links arising from chain transfer and branching during particle synthesis. The observations described herein provide insight into key design parameters associated with the synthesis of degradable hydrogel particles, which may be of use in various biotechnological applications. PMID:21425815

  4. 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.

  5. 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

  6. Revealing different aggregation pathways of amyloidogenic proteins by ultrasound velocimetry.

    PubMed

    Smirnovas, Vytautas; Winter, Roland

    2008-04-15

    In this work, we performed a detailed thermodynamic study, including ultrasound velocimetry, densimetry, calorimetry, and FTIR spectroscopy, of an aggregation-prone protein (insulin) under different salt-screening conditions to gain a deeper insight into the scenario of physicochemical events during its temperature-induced unfolding and aggregation reactions. Differences in aggregation and fibrillization pathways are reflected in changes of the partial molar volume, the coefficients of thermal expansion and compressibility, and the infrared spectral properties of the protein. Combining all experimental data allows setting up a scheme for the temperature-dependent insulin aggregation reaction in the presence and absence of NaCl. As revealed by complementary atomic force microscopy studies, under charge-screening conditions, a process involving structural reorganization, ripening, and formation of more compact nuclei from amorphous oligomers is involved in the formation of mature fibrillar morphologies. In this work, our focus was to put forward a comprehensive discussion of the use of ultrasound velocimetry in disentangling different aggregation pathways. In fact, ultrasound velocimetry proved to be very sensitive to changes in aggregation pathway, highlighting the importance of density and compressibility changes in the different aggregation and fibrillization reactions of the protein.

  7. Individual olfactory perception reveals meaningful nonolfactory genetic information.

    PubMed

    Secundo, Lavi; Snitz, Kobi; Weissler, Kineret; Pinchover, Liron; Shoenfeld, Yehuda; Loewenthal, Ron; Agmon-Levin, Nancy; Frumin, Idan; Bar-Zvi, Dana; Shushan, Sagit; Sobel, Noam

    2015-07-14

    Each person expresses a potentially unique subset of ∼ 400 different olfactory receptor subtypes. Given that the receptors we express partially determine the odors we smell, it follows that each person may have a unique nose; to capture this, we devised a sensitive test of olfactory perception we termed the "olfactory fingerprint." Olfactory fingerprints relied on matrices of perceived odorant similarity derived from descriptors applied to the odorants. We initially fingerprinted 89 individuals using 28 odors and 54 descriptors. We found that each person had a unique olfactory fingerprint (P < 10(-10)), which was odor specific but descriptor independent. We could identify individuals from this pool using randomly selected sets of 7 odors and 11 descriptors alone. Extrapolating from this data, we determined that using 34 odors and 35 descriptors we could individually identify each of the 7 billion people on earth. Olfactory perception, however, fluctuates over time, calling into question our proposed perceptual readout of presumably stable genetic makeup. To test whether fingerprints remain informative despite this temporal fluctuation, building on the linkage between olfactory receptors and HLA, we hypothesized that olfactory perception may relate to HLA. We obtained olfactory fingerprints and HLA typing for 130 individuals, and found that olfactory fingerprint matching using only four odorants was significantly related to HLA matching (P < 10(-4)), such that olfactory fingerprints can save 32% of HLA tests in a population screen (P < 10(-6)). In conclusion, a precise measure of olfactory perception reveals meaningful nonolfactory genetic information.

  8. Laser microsurgery reveals conserved viscoelastic behavior of the kinetochore.

    PubMed

    Cojoc, Gheorghe; Roscioli, Emanuele; Zhang, Lijuan; García-Ulloa, Alfonso; Shah, Jagesh V; Berns, Michael W; Pavin, Nenad; Cimini, Daniela; Tolić, Iva M; Gregan, Juraj

    2016-03-28

    Accurate chromosome segregation depends on proper kinetochore-microtubule attachment. Upon microtubule interaction, kinetochores are subjected to forces generated by the microtubules. In this work, we used laser ablation to sever microtubules attached to a merotelic kinetochore, which is laterally stretched by opposing pulling forces exerted by microtubules, and inferred the mechanical response of the kinetochore from its length change. In both mammalian PtK1 cells and in the fission yeast Schizosaccharomyces pombe, kinetochores shortened after microtubule severing. Interestingly, the inner kinetochore-centromere relaxed faster than the outer kinetochore. Whereas in fission yeast all kinetochores relaxed to a similar length, in PtK1 cells the more stretched kinetochores remained more stretched. Simple models suggest that these differences arise because the mechanical structure of the mammalian kinetochore is more complex. Our study establishes merotelic kinetochores as an experimental model for studying the mechanical response of the kinetochore in live cells and reveals a viscoelastic behavior of the kinetochore that is conserved in yeast and mammalian cells. PMID:27002163

  9. Angiosperm genome comparisons reveal early polyploidy in the monocot lineage

    PubMed Central

    Tang, Haibao; Bowers, John E.; Wang, Xiyin; Paterson, Andrew H.

    2009-01-01

    Although the timing and extent of a whole-genome duplication occurring in the common lineage of most modern cereals are clear, the existence or extent of more ancient genome duplications in cereals and perhaps other monocots has been hinted at, but remain unclear. We present evidence of additional duplication blocks of deeper hierarchy than the pancereal rho (ρ) duplication, covering at least 20% of the cereal transcriptome. These more ancient duplicated regions, herein called σ, are evident in both intragenomic and intergenomic analyses of rice and sorghum. Resolution of such ancient duplication events improves the understanding of the early evolutionary history of monocots and the origins and expansions of gene families. Comparisons of syntenic blocks reveal clear structural similarities in putatively homologous regions of monocots (rice) and eudicots (grapevine). Although the exact timing of the σ-duplication(s) is unclear because of uncertainties of the molecular clock assumption, our data suggest that it occurred early in the monocot lineage after its divergence from the eudicot clade. PMID:19966307

  10. A novel assay reveals hygrotactic behavior in Drosophila.

    PubMed

    Ji, Feiteng; Zhu, Yan

    2015-01-01

    Humidity is one of the most important factors that determines the geographical distribution and survival of terrestrial animals. The ability to detect variation in humidity is conserved across many species. Here, we established a novel behavioral assay that revealed the thirsty Drosophila exhibits strong hygrotactic behavior, and it can locate water by detecting humidity gradient. In addition, exposure to high levels of moisture was sufficient to elicit proboscis extension reflex behavior in thirsty flies. Furthermore, we found that the third antennal segment was necessary for hygrotactic behavior in thirsty flies, while arista was required for the avoidance of moist air in hydrated flies. These results indicated that two types of hygroreceptor cells exist in Drosophila: one located in the third antennal segment that mediates hygrotactic behavior in thirst status, and the other located in arista which is responsible for the aversive behavior toward moist air in hydration status. Using a neural silencing screen, we demonstrated that synaptic output from the mushroom body α/β surface and posterior neurons was required for both hygrotactic behavior and moisture-aversive behavior.

  11. Mitochondrial Genome Sequences Effectively Reveal the Phylogeny of Hylobates Gibbons

    PubMed Central

    Chan, Yi-Chiao; Roos, Christian; Inoue-Murayama, Miho; Inoue, Eiji; Shih, Chih-Chin; Pei, Kurtis Jai-Chyi; Vigilant, Linda

    2010-01-01

    Background Uniquely among hominoids, gibbons exist as multiple geographically contiguous taxa exhibiting distinctive behavioral, morphological, and karyotypic characteristics. However, our understanding of the evolutionary relationships of the various gibbons, especially among Hylobates species, is still limited because previous studies used limited taxon sampling or short mitochondrial DNA (mtDNA) sequences. Here we use mtDNA genome sequences to reconstruct gibbon phylogenetic relationships and reveal the pattern and timing of divergence events in gibbon evolutionary history. Methodology/Principal Findings We sequenced the mitochondrial genomes of 51 individuals representing 11 species belonging to three genera (Hylobates, Nomascus and Symphalangus) using the high-throughput 454 sequencing system with the parallel tagged sequencing approach. Three phylogenetic analyses (maximum likelihood, Bayesian analysis and neighbor-joining) depicted the gibbon phylogenetic relationships congruently and with strong support values. Most notably, we recover a well-supported phylogeny of the Hylobates gibbons. The estimation of divergence times using Bayesian analysis with relaxed clock model suggests a much more rapid speciation process in Hylobates than in Nomascus. Conclusions/Significance Use of more than 15 kb sequences of the mitochondrial genome provided more informative and robust data than previous studies of short mitochondrial segments (e.g., control region or cytochrome b) as shown by the reliable reconstruction of divergence patterns among Hylobates gibbons. Moreover, molecular dating of the mitogenomic divergence times implied that biogeographic change during the last five million years may be a factor promoting the speciation of Sundaland animals, including Hylobates species. PMID:21203450

  12. Knock-out models reveal new aquaporin functions.

    PubMed

    Verkman, Alan S

    2009-01-01

    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. Trends in the global tropopause thickness revealed by radiosondes

    NASA Astrophysics Data System (ADS)

    Feng, Sha; Fu, Yunfei; Xiao, Qingnong

    2012-10-01

    The first global trends in the thickness of the tropopause layer (TL) are analyzed based on radiosonde data in the Integrated Global Radiosonde Archive (IGRA) for the period of 1965-2004. It reveals that TL has been thickening for the entire globe with positive trends of 0.16 ± 0.12 km/decade during this period. Statistically significant thickening is observed in the tropics, North Hemisphere (NH) extratropics, and NH poles. Accompanied by overall cooling of -0.58 ± 0.40 K/decade in TL's top, remarkable rising trends of 0.35 ± 0.29 km/decade are observed in the correspoding height. However, the anti-correlation of the trends in the tropopause temperature and the corresponding height is not observed in its lower boundary, namely the first lapse rate tropopause (LRT), for all the latitude bands as suggested by the previous studies. The results imply that the temperature of the TL is primarily couple with the height of its upper boundary as the thickness of the TL is more correlated with the temperature of the lower stratosphere than with the tempeature of the upper troposphere. Long-term changes in TL may in turn carry more information how tropopause change in response to climate change than in the sharp “tropopause surface” only.

  14. Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs

    SciTech Connect

    Curtis, Bruce A.; Tanifuji, Goro; Burki, Fabien; Gruber, Ansgar; Irimia, Manuuel; Maruyama, Shinichiro; Arias, Maria C.; Ball, Steven G.; Gile, Gillian H.; Hirakawa, Yoshihisa; Hopkins, Julia F.; Kuo, Alan; Rensing, Stefan A.; Schmutz, Jeremy; Symeonidi, Aikaterini; Elias, Marek; Eveleigh, Robert J. M.; Herman, Emily K.; Klute, Mary J.; Nakayama, Takuro; Obornik, Miroslav; Reyes-Prieto, Adrian; Armbrust, E. Virginia; Aves, Stephen J.; Beiko, Robert G.; Coutinho, Pedro; Dacks, Joel B.; Durnford, Dion G.; Fast, Naomi M.; Green, Beverley R.; Grisdale, Cameron J.; Hempel, Franziska; Henrissat, Bernard; Hoppner, Marc P.; Ishida, Ken-Ichiro; Kim, Eunsoo; Koreny, Ludek; Kroth, Peter G.; Liu, Yuan; Malik, Shehre-Banoo; Maier, Uwe G.; McRose, Darcy; Mock, Thomas; Neilson, Jonathan A. D.; Onodera, Naoko T.; Poole, Anthony M.; Pritham, Ellen J.; Richards, Thomas A.; Rocap, Gabrielle; Roy, Scott W.; Sarai, Chihiro; Schaack, Sarah; Shirato, Shu; Slamovits, Claudio H.; Spencer, Davie F.; Suzuki, Shigekatsu; Worden, Alexandra Z.; Zauner, Stefan; Barry, Kerrie; Bell, Callum; Bharti, Arvind K.; Crow, John A.; Grimwood, Jane; Kramer, Robin; Lindquist, Erika; Lucas, Susan; Salamov, Asaf; McFadden, Geoffrey I.; Lane, Christopher E.; Keeling, Patrick J.; Gray, Michael W.; Grigoriev, Igor V.; Archibald, John M.

    2012-08-10

    Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have 21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host- and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.

  15. Fine-scaled human genetic structure revealed by SNP microarrays.

    PubMed

    Xing, Jinchuan; Watkins, W Scott; Witherspoon, David J; Zhang, Yuhua; Guthery, Stephen L; Thara, Rangaswamy; Mowry, Bryan J; Bulayeva, Kazima; Weiss, Robert B; Jorde, Lynn B

    2009-05-01

    We report an analysis of more than 240,000 loci genotyped using the Affymetrix SNP microarray in 554 individuals from 27 worldwide populations in Africa, Asia, and Europe. To provide a more extensive and complete sampling of human genetic variation, we have included caste and tribal samples from two states in South India, Daghestanis from eastern Europe, and the Iban from Malaysia. Consistent with observations made by Charles Darwin, our results highlight shared variation among human populations and demonstrate that much genetic variation is geographically continuous. At the same time, principal components analyses reveal discernible genetic differentiation among almost all identified populations in our sample, and in most cases, individuals can be clearly assigned to defined populations on the basis of SNP genotypes. All individuals are accurately classified into continental groups using a model-based clustering algorithm, but between closely related populations, genetic and self-classifications conflict for some individuals. The 250K data permitted high-level resolution of genetic variation among Indian caste and tribal populations and between highland and lowland Daghestani populations. In particular, upper-caste individuals from Tamil Nadu and Andhra Pradesh form one defined group, lower-caste individuals from these two states form another, and the tribal Irula samples form a third. Our results emphasize the correlation of genetic and geographic distances and highlight other elements, including social factors that have contributed to population structure. PMID:19411602

  16. Revealing the intricate effect of collaboration on innovation.

    PubMed

    Inoue, Hiroyasu; Liu, Yang-Yu

    2015-01-01

    We studied the Japan and U.S. patent records of several decades to demonstrate the effect of collaboration on innovation. We found that statistically inventor teams slightly outperform solo inventors while company teams perform equally well as solo companies. By tracking the performance record of individual teams, we found that inventor teams' performance generally degrades with more repeat collaborations. Though company teams' performance displays strongly bursty behavior, long-term collaboration does not significantly help innovation. To systematically study the effect of repeat collaboration, we defined the repeat collaboration number of a team as the average number of collaborations over all the teammate pairs. We found that mild repeat collaboration improves the performance of Japanese inventor teams and U.S. company teams. Yet, excessive repeat collaboration does not significantly help innovation at both the inventor and company levels in both countries. To control for unobserved heterogeneity, we performed a detailed regression analysis and the results were consistent with our simple observations. The presented results revealed the intricate effect of collaboration on innovation, which may also be observed in other creative projects. PMID:25799138

  17. 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.

  18. Tremor patches in Cascadia revealed by seismic array analysis

    NASA Astrophysics Data System (ADS)

    Ghosh, Abhijit; Vidale, John E.; Sweet, Justin R.; Creager, Kenneth C.; Wech, Aaron G.

    2009-09-01

    Episodic tremor and slip (ETS) events in Cascadia have recently been observed, illuminating the general area that radiates seismic energy in the form of non-volcanic tremor (NVT). However, the picture of the ETS zone remains fuzzy because of difficulties in tremor detection and location. To observe the intimate details of tremor, we deployed a dense 84-element small-aperture seismic array on the Olympic Peninsula, Washington, above the tremor migration path. It recorded the main ETS event in May 2008, as well as a weaker tremor episode two months earlier. Using a beamforming technique, we are able to capture and track tremor activity with an unprecedented resolution from southern Puget Sound to the Strait of Juan de Fuca. The array technique reveals up to four times more duration of tremor compared to the conventional envelope cross-correlation method. Our findings suggest that NVT is not uniformly distributed on the subduction interface, and unveils several distinct patches that release much of the tremor moment. The patches appear to be devoid of ordinary earthquakes, and may indicate the heterogeneity in fault strength that affects the modes of stress release within the ETS zone.

  19. Revealing amphiphilic nanodomains of anti-biofouling polymer coatings.

    PubMed

    Amadei, Carlo A; Yang, Rong; Chiesa, Matteo; Gleason, Karen K; Santos, Sergio

    2014-04-01

    Undesired bacterial adhesion and biofilm formation on wetted surfaces leads to significant economic and environmental costs in various industries. Amphiphilic coatings with molecular hydrophilic and hydrophobic patches can mitigate such biofouling effectively in an environmentally friendly manner. The coatings are synthesized by copolymerizing (Hydroxyethyl)methacrylate and perfluorodecylacrylate via initiated chemical vapor deposition (iCVD). In previous studies, the size of the patches was estimated to be ∼1.4-1.75 nm by fitting protein adsorption data to a theoretical model. However, no direct observations of the molecular heterogeneity exist and therefore the origin of the fouling resistance of amphiphilic coatings remains unclear. Here, the amphiphilic nature is investigated by amplitude modulation atomic force microscopy (AM-AFM). High-resolution images obtained by penetrating and oscillating the AFM tip under the naturally present water layer with sub-nanometer amplitudes reveal, for the first time, the existence of amphiphilic nanodomains (1-2 nm(2)). Compositional heterogeneity at the nanoscale is further corroborated by a statistical analysis on the data obtained with dynamic AM-AFM force spectroscopy. Variations in the long range attractive forces, responsible for water affinity, are also identified. These nanoscopic results on the polymers wettability are also confirmed by contact angle measurements (i.e., static and dynamic). The unprecedented ability to visualize the amphiphilic nanodomains as well as sub-nanometer crystalline structures provides strong evidence for the existence of previously postulated nanostructures, and sheds light on the underlying antifouling mechanism of amphiphilic chemistry. PMID:24617757

  20. Single molecule studies reveal new mechanisms for microtubule severing

    NASA Astrophysics Data System (ADS)

    Ross, Jennifer; Diaz-Valencia, Juan Daniel; Morelli, Margaret; Zhang, Dong; Sharp, David

    2011-03-01

    Microtubule-severing enzymes are hexameric complexes made from monomeric enzyme subunits that remove tubulin dimers from the microtubule lattice. Severing proteins are known to remodel the cytoskeleton during interphase and mitosis, and are required in proper axon morphology and mammalian bone and cartilage development. We have performed the first single molecule imaging to determine where and how severing enzymes act to cut microtubules. We have focused on the original member of the group, katanin, and the newest member, fidgetin to compare their biophysical activities in vitro. We find that, as expected, severing proteins localize to areas of activity. Interestingly, the association is very brief: they do not stay bound nor do they bind cooperatively at active sites. The association duration changes with the nucleotide content, implying that the state in the catalytic cycle dictates binding affinity with the microtubule. We also discovered that, at lower concentrations, both katanin and fidgetin can depolymerize taxol-stabilized microtubules by removing terminal dimers. These studies reveal the physical regulation schemes to control severing activity in cells, and ultimately regulate cytoskeletal architecture. This work is supported by the March of Dimes Grant #5-FY09-46.

  1. Statistical universals reveal the structures and functions of human music

    PubMed Central

    Savage, Patrick E.; Brown, Steven; Sakai, Emi; Currie, Thomas E.

    2015-01-01

    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. PMID:26124105

  2. Revealing accretion onto black holes through X-ray reflection

    NASA Astrophysics Data System (ADS)

    Plant, D.; Fender, R.; Ponti, G.; Munoz-Darias, T.; Coriat, M.

    2014-07-01

    Understanding the dynamics behind black hole state transitions and the changes they reflect in outbursts has become long-standing problem. The X-ray reflection spectrum describes the interaction between the hard X-ray source (the power-law continuum) and the cool accretion disc it illuminates, and thus permits an indirect view of how the two evolve. We present a systematic analysis of the reflection spectrum throughout three outbursts (500+ RXTE observations) of the black hole binary GX 339-4, representing the largest study applying a self-consistent treatment of reflection to date. Particular attention is payed to the coincident evolution of the power-law and reflection, which can be used to determine the accretion geometry. The hard state is found to be distinctly reflection weak, however the ratio of reflection to power-law gradually increases as the source luminosity rises. In contrast the reflection is found dominate the power-law throughout most of the soft state, with increasing supremacy as the source decays. Using results from archival and AO-12 observations of GX 339-4 with XMM-Newton we reveal the dynamics driving this evolution and the nature of accretion onto black holes in outburst.

  3. [Meningococcal Septicemia Revealing Multiple Myeloma: A Case Report].

    PubMed

    Arakawa, Risturo; Mori, Nobuaki; Kagawa, Narito; Higuchi, Akiko; Tanaka, Masashi; Aoki, Yasuko; Seki, Shiko; Suzuki, Ryo

    2016-05-01

    Meningococcal infection is among the most devastating diseases. It is rarely seen in Japan. However, several environmental and host factors have been associated with increased risks of Neisseria meningitidis infection. We present a case of invasive N. meningitidis infection that revealed the presence of multiple myeloma. A 55-year-old Japanese man was admitted with fever and altered consciousness. He was sent to the intensive care unit for septic shock and disseminated intravascular coagulation. In addition to standard septic shock and multiple organ failure treatment, polymyxin-B immobilized column direct hemoperfusion was performed. His blood culture was positive for N. meningitidis. The patient gradually improved and was discharged on day 35. We evaluated the risk factors for the development of meningococcal infection. A laboratory examination showed that the patient was negative for human immunodeficiency virus antibody and had a normal total complement function. However, his serum immunoglobulin G level was high, and serum and urine protein electrophoresis detected a monoclonal gammopathy. A bone marrow examination led to the diagnosis of multiple myeloma. Because N. meningitidis bacteria spreads between individuals in close contact through the exchange of oral secretions, droplet precautions and antimicrobial chemoprophylaxis (ciprofloxacin, 500 mg) were implemented to prevent the spread of the meningococcal infection. Sporadic meningococcal infection warrants an evaluation for immunodeficiency and the prevention of secondary infection. PMID:27529971

  4. 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

    2015-06-01

    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.

  5. Spatial Congruity Effects Reveal Metaphorical Thinking, not Polarity Correspondence.

    PubMed

    Dolscheid, Sarah; Casasanto, Daniel

    2015-01-01

    Spatial congruity effects have often been interpreted as evidence for metaphorical thinking, but an alternative account based on polarity correspondence (a.k.a. markedness) has challenged this view. Here we compared metaphor- and polarity-correspondence-based explanations for spatial congruity effects, using musical pitch as a testbed. In one experiment, English speakers classified high- and low-frequency pitches as "high" and "low," or as "front" and "back," to determine whether space-pitch congruity effects could be elicited by any marked spatial continuum. Although both pairs of terms describe bipolar spatial continuums, we found congruity effects only for high/low judgments, indicating that markedness is not sufficient to produce space-pitch congruity effects. A second experiment confirmed that there were no space-pitch congruity effects for another pair of terms that have clear markedness (big/small), but which do not denote spatial height. By contrast, this experiment showed congruity effects for words that cued an appropriate vertical spatial schema (tall/short), even though these words are not used conventionally in English to describe pitches, ruling out explanations for the observed pattern of results based on verbal polysemy. Together, results suggest that space-pitch congruity effects reveal metaphorical uses of spatial schemas, not polarity correspondence effects. PMID:26635713

  6. 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

    2007-10-01

    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+. PMID:17914902

  7. Single-cell chromatin accessibility reveals principles of regulatory variation

    PubMed Central

    Buenrostro, Jason D.; Wu, Beijing; Litzenburger, Ulrike M.; Ruff, Dave; Gonzales, Michael L.; Snyder, Michael P.; Chang, Howard Y.; Greenleaf, William J.

    2015-01-01

    Cell-to-cell variation is a universal feature of life that impacts a wide range of biological phenomena, from developmental plasticity1,2 to tumor heterogeneity3. While recent advances have improved our ability to document cellular phenotypic variation4–8 the fundamental mechanisms that generate variability from identical DNA sequences remain elusive. Here we reveal the landscape and principles of cellular DNA regulatory variation by developing a robust method for mapping the accessible genome of individual cells via assay for transposase-accessible chromatin using sequencing (ATAC-seq). Single-cell ATAC-seq (scATAC-seq) maps from hundreds of single-cells in aggregate closely resemble accessibility profiles from tens of millions of cells and provides insights into cell-to-cell variation. Accessibility variance is systematically associated with specific trans-factors and cis-elements, and we discover combinations of trans-factors associated with either induction or suppression of cell-to-cell variability. We further identify sets of trans-factors associated with cell-type specific accessibility variance across 8 cell types. Targeted perturbations of cell cycle or transcription factor signaling evoke stimulus-specific changes in this observed variability. The pattern of accessibility variation in cis across the genome recapitulates chromosome topological domains9 de novo, linking single-cell accessibility variation to three-dimensional genome organization. All together, single-cell analysis of DNA accessibility provides new insight into cellular variation of the “regulome.” PMID:26083756

  8. Crystallographic and spectroscopic snapshots reveal a dehydrogenase in action

    DOE PAGESBeta

    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 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. 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. 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

  11. 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.

  12. Modeling malaria genomics reveals transmission decline and rebound in Senegal

    PubMed Central

    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.

    2015-01-01

    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. PMID:25941365

  13. Revealing water’s secrets: deuterium depleted water

    PubMed Central

    2013-01-01

    Background The anomalous properties of water have been of great interest for generations of scientists. However the impact of small amount of deuterium content which is always present in water has never been explored before. For the first time the fundamental properties of deuterium depleted (light) water at 4°C and 20°C are here presented. Results The obtained results show the important role of the deuterium in the properties of bulk water. At 4°C the lowest value of the kinematic viscosity (1.46 mm2/s) has been found for 96.5 ppm D/H ratio. The significant deviation in surface tension values has been observed in deuterium depleted water samples at the both temperature regimes. The experimental data provides direct evidence that density, surface tension and viscosity anomalies of water are caused by the presence of variable concentration of deuterium which leads to the formation of water clusters of different size and quantity. Conclusions The investigated properties of light water reveal the origin of the water anomalies. The new theoretical model of cluster formation with account of isotope effect is proposed. PMID:23773696

  14. Multiple etiologies for Alzheimer disease are revealed by segregation analysis

    SciTech Connect

    Rao, V.S.; Connor-Lacke, L.; Cupplies, L.A.; Growdon, J.H.; Farrer, L.A.; Duijn, C.M. van

    1994-11-01

    We have evaluated several transmission models for Alzheimer disease (AD), using the logistic regressive approach in 401 nuclear families of consecutively ascertained and rigorously diagnosed probands. Models postulating no major gene effect, random environmental transmission, recessive inheritance, and sporadic occurrence were rejected under varied assumptions regarding the associations among sex, age, and major gene susceptibility. Transmission of the disorder was not fully explained by a single Mendelian model for all families. Stratification of families as early- and late-onset by using the median of family mean onset ages showed that, regardless of the model studied, two groups of families fit better than a single group. AD in early-onset families is transmitted as an autosomal dominant trait with full penetrance in both sexes and has a gene frequency of 1.5%. Dominant inheritance also gave the best fit of the data in late-onset families, but this hypothesis was rejected, suggesting the presence of heterogeneity within this subset. Our study also revealed that genetically nonsusceptible males and females develop AD, indicating the presence of phenocopies within early-onset and late-onset groups. Moreover, our results suggest that the higher risk to females is not solely due to their increased longevity. 50 refs., 5 tabs.

  15. [Information processing in the human brain revealed by eyeblink].

    PubMed

    Nakano, Tamami

    2014-01-01

    People spontaneously generate an eyeblink every few seconds. It is generally accepted that eyeblinks are necessary for ocular lubrication, but spontaneous eyeblinks actually occur several times more frequently than necessary for lubrication. Thus, the functional role of most spontaneous eyeblinks has remained unclear. We found that peoples blinked in synchrony while viewing the same video stories. This blink synchronization specifically occured at the implicit breakpoints of the video stories. Moreover, in face-to-face communication, the listeners blinked with a delay of 0.25-0.5 s after the speaker blinked at the end and during pauses in speech. In contrast, the individuals with autism spectrum disorders, which are characterized by impaired social communication, did not show any eyeblink synchronization with the speaker. These facts demonstrate that spontaneous eyeblink is involved in the contextual segmentation of information, and that eyeblinks have a social function to share the contextual segmentation with others. Futhermore, our neuroimaging study revealed that, while viewing videos, cortical activity momentarily decreases in the dorsal attention network after blink onset but increases in the default-mode network. These results suggest that the spontaneous eyeblink is involved in the disengagement of attention at an implicit contextual breakpoint by controlling the balance between the two competing networks. PMID:24371126

  16. 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.

  17. 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

  18. 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.

  19. Recombination patterns reveal information about centromere location on linkage maps.

    PubMed

    Limborg, Morten T; McKinney, Garrett J; Seeb, Lisa W; Seeb, James E

    2016-05-01

    Linkage mapping is often used to identify genes associated with phenotypic traits and for aiding genome assemblies. Still, many emerging maps do not locate centromeres - an essential component of the genomic landscape. Here, we demonstrate that for genomes with strong chiasma interference, approximate centromere placement is possible by phasing the same data used to generate linkage maps. Assuming one obligate crossover per chromosome arm, information about centromere location can be revealed by tracking the accumulated recombination frequency along linkage groups, similar to half-tetrad analyses. We validate the method on a linkage map for sockeye salmon (Oncorhynchus nerka) with known centromeric regions. Further tests suggest that the method will work well in other salmonids and other eukaryotes. However, the method performed weakly when applied to a male linkage map (rainbow trout; O. mykiss) characterized by low and unevenly distributed recombination - a general feature of male meiosis in many species. Further, a high frequency of double crossovers along chromosome arms in barley reduced resolution for locating centromeric regions on most linkage groups. Despite these limitations, our method should work well for high-density maps in species with strong recombination interference and will enrich many existing and future mapping resources. PMID:26561199

  20. Network Clustering Revealed the Systemic Alterations of Mitochondrial Protein Expression

    PubMed Central

    Koo, Hyun-Jung; Park, Wook-Ha; Yang, Jae-Seong; Yu, Myeong-Hee; Kim, Sanguk; Pak, Youngmi Kim

    2011-01-01

    The mitochondrial protein repertoire varies depending on the cellular state. Protein component modifications caused by mitochondrial DNA (mtDNA) depletion are related to a wide range of human diseases; however, little is known about how nuclear-encoded mitochondrial proteins (mt proteome) changes under such dysfunctional states. In this study, we investigated the systemic alterations of mtDNA-depleted (ρ0) mitochondria by using network analysis of gene expression data. By modularizing the quantified proteomics data into protein functional networks, systemic properties of mitochondrial dysfunction were analyzed. We discovered that up-regulated and down-regulated proteins were organized into two predominant subnetworks that exhibited distinct biological processes. The down-regulated network modules are involved in typical mitochondrial functions, while up-regulated proteins are responsible for mtDNA repair and regulation of mt protein expression and transport. Furthermore, comparisons of proteome and transcriptome data revealed that ρ0 cells attempted to compensate for mtDNA depletion by modulating the coordinated expression/transport of mt proteins. Our results demonstrate that mt protein composition changed to remodel the functional organization of mitochondrial protein networks in response to dysfunctional cellular states. Human mt protein functional networks provide a framework for understanding how cells respond to mitochondrial dysfunctions. PMID:21738461