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Sample records for complex mg-ni-la-co-h phases

  1. Griffiths Phases on Complex Networks

    NASA Astrophysics Data System (ADS)

    Muñoz, Miguel A.; Juhász, Róbert; Castellano, Claudio; Ódor, Géza

    2010-09-01

    Quenched disorder is known to play a relevant role in dynamical processes and phase transitions. Its effects on the dynamics of complex networks have hardly been studied. Aimed at filling this gap, we analyze the contact process, i.e., the simplest propagation model, with quenched disorder on complex networks. We find Griffiths phases and other rare-region effects, leading rather generically to anomalously slow (algebraic, logarithmic, …) relaxation, on Erdős-Rényi networks. Similar effects are predicted to exist for other topologies with a finite percolation threshold. More surprisingly, we find that Griffiths phases can also emerge in the absence of quenched disorder, as a consequence of topological heterogeneity in networks with finite topological dimension. These results have a broad spectrum of implications for propagation phenomena and other dynamical processes on networks.

  2. Phase distribution in complex geometry conduits

    SciTech Connect

    Lahey, R.T. Jr.; Lopez de Bertodano, M.; Jones, O.C. Jr.

    1992-12-31

    Some of the most important and challenging problems in two-phase flow today have to do with the understanding and prediction of multidimensional phenomena, in particular, lateral phase distribution in both simple and complex geometry conduits. A prior review paper summarized the state-of-the-art in the understanding of phase distribution phenomena, and the ability to perform mechanistic multidimensional predictions. The purpose of this paper is to update that review, with particular emphasis on complex geometry conduit predictive capabilities.

  3. Simulating Complex Modulated Phases Through Spin Models

    NASA Astrophysics Data System (ADS)

    Selinger, Jonathan V.; Lopatina, Lena M.; Geng, Jun; Selinger, Robin L. B.

    2009-03-01

    We extend the computational approach for studying striped phases on curved surfaces, presented in the previous talk, to two new problems involving complex modulated phases. First, we simulate a smectic liquid crystal on an arbitrary mesh by mapping the director field onto a vector spin and the density wave onto an Ising spin. We can thereby determine how the smectic phase responds to any geometrical constraints, including hybrid boundary conditions, patterned substrates, and disordered substrates. This method may provide a useful tool for designing ferroelectric liquid crystal cells. Second, we explore a model of vector spins on a flat two-dimensional (2D) lattice with long-range antiferromagnetic interactions. This model generates modulated phases with surprisingly complex structures, including 1D stripes and 2D periodic cells, which are independent of the underlying lattice. We speculate on the physical significance of these structures.

  4. Solid-phase preparation of protein complexes.

    PubMed

    Pengo, Paolo; Veggiani, Gianluca; Rattanamanee, Kwanchai; Gallotta, Andrea; Beneduce, Luca; Fassina, Giorgio

    2010-01-01

    Protein-protein conjugation is usually achieved by solution phase methods requiring concentrated protein solution and post-synthetic purification steps. In this report we describe a novel continuous-flow solid-phase approach enabling the assembly of protein complexes minimizing the amount of material needed and allowing the repeated use of the same solid phase. The method exploits an immunoaffinity matrix as solid support; the matrix reversibly binds the first of the complex components while the other components are sequentially introduced, thus allowing the complex to grow while immobilized. The tethering technique employed relies on the use of the very mild synthetic conditions and fast association rates allowed by the avidin-biotin system. At the end of the assembly, the immobilized complexes can be removed from the solid support and recovered by lowering the pH of the medium. Under the conditions used for the sequential complexation and recovery, the solid phase was not damaged or irreversibly modified and could be reused without loss of binding capacity. The method was specifically designed to prepare protein complexes to be used in immunometric methods of analysis, where the immunoreactivity of each component needs to be preserved. The approach was successfully exploited for the preparation of two different immunoaffinity reagents with immunoreactivity mimicking native squamous cell carcinoma antigen-immunoglobulin M (SCCA-IgM) and alphafetoprotein-immunoglobulin M (AFP-IgM) immune complexes, which were characterized by dedicated sandwich enzyme-linked immunosorbent assay (ELISA) and immunoblot. Besides the specific application described in the paper, the method is sufficiently general to be used for the preparation of a broad range of protein assemblies. PMID:21038355

  5. Phase equilibria for complex fluid mixtures

    SciTech Connect

    Prausnitz, J.M.

    1983-04-01

    After defining complex mixtures, attention is given to the canonical procedure used for the thermodynamics of fluid mixtures: first, we establish a suitable, idealized reference system and then we establish a perturbation (or excess function) which corrects the idealized system for real behavior. For complex mixtures containing identified components (e.g. alcohols, ketones, water) discussion is directed at possible techniques for extending to complex mixtures our conventional experience with reference systems and perturbations for simple mixtures. Possible extensions include generalization of the quasi-chemical approximation (local compositions) and superposition of chemical equilibria (association and solvation) on a physical equation of state. For complex mixtures containing unidentified components (e.g. coal-derived fluids), a possible experimental method is suggested for characterization; conventional procedures can then be used to calculate phase equilibria using the concept of pseudocomponents whose properties are given by the characterization data. Finally, as an alternative to the pseudocomponent method, a brief introduction is given to phase-equilibrium calculations using continuous thermodynamics.

  6. Thermoelectric Properties of Complex Zintl Phases

    NASA Astrophysics Data System (ADS)

    Snyder, G. Jeffrey

    2008-03-01

    Complex Zintl phases make ideal thermoelectric materials because they can exhibit the necessary ``electron-crystal, phonon-glass'' properties required for high thermoelectric efficiency. Complex crystal structures can lead to high thermoelectric figure of merit (zT) by having extraordinarily low lattice thermal conductivity. A recent example is the discovery that Yb14MnSb11, a complex Zintl compound, has twice the zT as the SiGe based material currently in use at NASA. The high temperature (300K - 1300K) electronic properties of Yb14MnSb11 can be understood using models for heavily doped semiconductors. The free hole concentration, confirmed by Hall effect measurements, is set by the electron counting rules of Zintl and the valence of the transition metal (Mn^+2). Substitution of nonmagnetic Zn^+2 for the magnetic Mn^+2 reduces the spin-disorder scattering and leads to increased zT (10%). The reduction of spin-disorder scattering is consistent with the picture of Yb14MnSb11 as an underscreened Kondo lattice as derived from low temperature measurements. The hole concentration can be reduced by the substitution of Al^+3 for Mn^+2, which leads to an increase in the Seebeck coefficient and electrical resistivity consistent with models for degenerate semiconductors. This leads to further improvements (about 25%) in zT and a reduction in the temperature where the zT peaks. The peak in zT is due to the onset of minority carrier conduction and can be correlated with reduction in Seebeck coefficient, increase in electrical conductivity and increase in thermal conductivity due to bipolar thermal conduction.

  7. Phase Behavior of Complex Superprotonic Solid Acids

    NASA Astrophysics Data System (ADS)

    Panithipongwut, Chatr

    Superprotonic phase transitions and thermal behaviors of three complex solid acid systems are presented, namely Rb3H(SO4) 2-RbHSO4 system, Rb3H(SeO4)2-Cs 3H(SeO4)2 solid solution system, and Cs6 (H2SO4)3(H1.5PO4) 4. These material systems present a rich set of phase transition characteristics that set them apart from other, simpler solid acids. A.C. impedance spectroscopy, high-temperature X-ray powder diffraction, and thermal analysis, as well as other characterization techniques, were employed to investigate the phase behavior of these systems. Rb3H(SO4)2 is an atypical member of the M3H(XO4)2 class of compounds (M = alkali metal or NH4+ and X = S or Se) in that a transition to a high-conductivity state involves disproportionation into two phases rather than a simple polymorphic transition [1]. In the present work, investigations of the Rb3H(SO4)2-RbHSO4 system have revealed the disproportionation products to be Rb2SO 4 and the previously unknown compound Rb5H3(SO 4)4. The new compound becomes stable at a temperature between 25 and 140 °C and is isostructural to a recently reported trigonal phase with space group P3m of Cs5H 3(SO4)4 [2]. At 185 °C the compound undergoes an apparently polymorphic transformation with a heat of transition of 23.8 kJ/mol and a slight additional increase in conductivity. The compounds Rb3H(SeO4)2 and Cs 3H(SeO4)2, though not isomorphous at ambient temperatures, are quintessential examples of superprotonic materials. Both adopt monoclinic structures at ambient temperatures and ultimately transform to a trigonal (R3m) superprotonic structure at slightly elevated temperatures, 178 and 183 °C, respectively. The compounds are completely miscible above the superprotonic transition and show extensive solubility below it. Beyond a careful determination of the phase boundaries, we find a remarkable 40-fold increase in the superprotonic conductivity in intermediate compositions rich in Rb as compared to either end-member. The compound Cs6(H2

  8. Complex phase behavior induced by repulsive interactions

    PubMed

    Velasco; Mederos; Navascues; Hemmer; Stell

    2000-07-01

    For a solid in which the interactions have a hard core plus a simple soft repulsive tail we show, using a perturbation theory, that the possible stable crystalline structures give rise to a rich phase behavior. We find two concomitant critical points each corresponding to phase transitions separating bcc and fcc structures, respectively, and the occurrence of a transition between fcc and bcc phases without change in density. This novel phenomenology may be relevant to the behavior of some metallic systems, colloids, and to water. PMID:10991174

  9. Complexities of One-Component Phase Diagrams

    ERIC Educational Resources Information Center

    Ciccioli, Andrea; Glasser, Leslie

    2011-01-01

    For most materials, the solid at and near the triple-point temperature is denser than the liquid with which it is in equilibrium. However, for water and certain other materials, the densities of the phases are reversed, with the solid being less dense. The profound consequences for the appearance of the "pVT" diagram of one-component materials…

  10. Dual-phase evolution in complex adaptive systems

    PubMed Central

    Paperin, Greg; Green, David G.; Sadedin, Suzanne

    2011-01-01

    Understanding the origins of complexity is a key challenge in many sciences. Although networks are known to underlie most systems, showing how they contribute to well-known phenomena remains an issue. Here, we show that recurrent phase transitions in network connectivity underlie emergent phenomena in many systems. We identify properties that are typical of systems in different connectivity phases, as well as characteristics commonly associated with the phase transitions. We synthesize these common features into a common framework, which we term dual-phase evolution (DPE). Using this framework, we review the literature from several disciplines to show that recurrent connectivity phase transitions underlie the complex properties of many biological, physical and human systems. We argue that the DPE framework helps to explain many complex phenomena, including perpetual novelty, modularity, scale-free networks and criticality. Our review concludes with a discussion of the way DPE relates to other frameworks, in particular, self-organized criticality and the adaptive cycle. PMID:21247947

  11. Chirality-selected phase behaviour in ionic polypeptide complexes

    SciTech Connect

    Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; Kade, Matthew J.; Priftis, Dimitrios; Black, Katie A.; Wong, Derek; Klein, Ryan A.; Pierce, III, Charles F.; Margossian, Khatcher O.; Whitmer, Jonathan K.; Qin, Jian; de Pablo, Juan J.; Tirrell, Matthew

    2015-01-14

    In this study, polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with a β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation.

  12. Chirality-selected phase behaviour in ionic polypeptide complexes

    DOE PAGESBeta

    Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; Kade, Matthew J.; Priftis, Dimitrios; Black, Katie A.; Wong, Derek; Klein, Ryan A.; Pierce, III, Charles F.; Margossian, Khatcher O.; et al

    2015-01-14

    In this study, polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with amore » β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation.« less

  13. Chirality-selected phase behaviour in ionic polypeptide complexes

    PubMed Central

    Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; Kade, Matthew J.; Priftis, Dimitrios; Black, Katie A.; Wong, Derek; Klein, Ryan A.; Pierce, Charles F.; Margossian, Khatcher O.; Whitmer, Jonathan K.; Qin, Jian; de Pablo, Juan J.; Tirrell, Matthew

    2015-01-01

    Polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with a β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation. PMID:25586861

  14. Chirality-selected phase behaviour in ionic polypeptide complexes

    NASA Astrophysics Data System (ADS)

    Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; Kade, Matthew J.; Priftis, Dimitrios; Black, Katie A.; Wong, Derek; Klein, Ryan A.; Pierce, Charles F.; Margossian, Khatcher O.; Whitmer, Jonathan K.; Qin, Jian; de Pablo, Juan J.; Tirrell, Matthew

    2015-01-01

    Polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with a β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation.

  15. Phase sensitivity of complex cells in primary visual cortex.

    PubMed

    Hietanen, M A; Cloherty, S L; van Kleef, J P; Wang, C; Dreher, B; Ibbotson, M R

    2013-05-01

    Neurons in the primary visual cortex are often classified as either simple or complex based on the linearity (or otherwise) of their response to spatial luminance contrast. In practice, classification is typically based on Fourier analysis of a cell's response to an optimal drifting sine-wave grating. Simple cells are generally considered to be linear and produce responses modulated at the fundamental frequency of the stimulus grating. In contrast, complex cells exhibit significant nonlinearities that reduce the response at the fundamental frequency. Cells can therefore be easily and objectively classified based on the relative modulation of their responses - the ratio of the phase-sensitive response at the fundamental frequency of the stimulus (F₁) to the phase-invariant sustained response (F₀). Cells are classified as simple if F₁/F₀>1 and complex if F₁/F₀<1. This classification is broadly consistent with criteria based on the spatial organisation of cells' receptive fields and is accordingly presumed to reflect disparate functional roles of simple and complex cells in coding visual information. However, Fourier analysis of spiking responses is sensitive to the number of spikes available - F₁/F₀ increases as the number of spikes is reduced, even for phase-invariant complex cells. Moreover, many complex cells encountered in the laboratory exhibit some phase sensitivity, evident as modulation of their responses at the fundamental frequency. There currently exists no objective quantitative means of assessing the significance or otherwise of these modulations. Here we derive a statistical basis for objectively assessing whether the modulation of neuronal responses is reliable, thereby adding a level of statistical certainty to measures of phase sensitivity. We apply our statistical analysis to neuronal responses to moving sine-wave gratings recorded from 367 cells in cat primary visual cortex. We find that approximately 60% of complex cells exhibit

  16. Molecular Complexation and Phase Diagrams of Urea/PEG Mixtures

    NASA Astrophysics Data System (ADS)

    Fu, Guoepeng; Kyu, Thein

    2014-03-01

    Polyethylene glycol (PEG) and urea complexation has been known to form a stable crystal due to molecular complexation. The effect of molecular weight of PEG on the phase diagrams of its blends with urea has been explored. In the case of high molecular weight PEG8k/urea, the observed phase diagram is azeotrope, accompanied by eutectoid reactions in the submerged phases such as induced stable ``alpha'' phase crystals and metastable ``beta'' phase crystals. The metastable crystal can transform to stable crystal under a certain thermal annealing condition. However, the phase diagram of PEG1k/urea is of coexistence loop, whereas PEG400/urea exhibits eutectic character. Subsequently, the change of azeotrope to eutectic behavior with PEG molecular weight is analyzed in the context of the combined Flory-Huggins theory of liquid-liquid demixing and phase field theory of crystal solidification. Of particular interest is that only a very small urea amount (2 wt%) is needed to form a stable inclusion crystal via complexation with PEG. Potential application in lithium battery is discussed based on AC impedance spectroscopy and cyclic voltammetry. Supported by NSF-DMR 1161070.

  17. Phase Transitions in Nanostructured Polyelectrolyte-Surfactant Complexes

    NASA Astrophysics Data System (ADS)

    Leonard, Michael; Strey, Helmut

    2001-03-01

    When a water-soluble polyelectrolyte is combined with an oppositely-charged surfactant solution at a stoichiometric charge ratio, self-assembly into highly-ordered, water-insoluble structures occurs. We have prepared such complexes with poly(sodium acrylate)-co-acrylamide, alginic acid, and chitosan, combined with cationic and anionic surfactants. The phases exhibited by these complexes in aqueous solution are highly sensitive to such factors as osmotic pressure, salt type, ionic strength, and polyelectrolyte charge density. In this study, we have used small angle X-ray scattering to examine osmotic stress-induced structural phase transitions in these complexes under these various environmental conditions. The morphological consequences of combining polyelectrolytes with swollen, emulsion-bound surfactant micelles were also investigated. Results of this work, as well as the potential to use these complexes as nanoporous, biocompatible materials, will be discussed.

  18. Phase-retrieval ghost imaging of complex-valued objects

    SciTech Connect

    Gong Wenlin; Han Shensheng

    2010-08-15

    An imaging approach, based on ghost imaging, is reported to recover a pure-phase object or a complex-valued object. Our analytical results, which are backed up by numerical simulations, demonstrate that both the complex-valued object and its amplitude-dependent part can be separately and nonlocally reconstructed using this approach. Both effects influencing the quality of reconstructed images and methods to further improve the imaging quality are also discussed.

  19. Complexes of in-phase two-dimensional laser solitons

    SciTech Connect

    Rosanov, N N; Fedorov, S V; Shatsev, A N

    2008-01-31

    The structure and motion of complexes of in-phase weakly coupled fundamental solitons in a wide-aperture class A laser with saturable absorption are analysed. The symmetry of the field distribution and its relation to the motion of the complex are studied. Due to the absence of wavefront dislocations in such complexes, the transverse radiation intensity and phase distributions are the symmetry objects, which simplifies analysis compared to the case when wavefront dislocations are present. Four types of the motion of soliton complexes are demonstrated: a motionless complex in the presence of two mirror symmetry axes; linear motion of the complex when only one mirror symmetry axis exists; rotation around a motionless centre of inertia in the absence of the mirror symmetry axis and in the presence of symmetry with respect to rotation through the angle 2{pi}/M (M is an integer); and curvilinear (circular) motion of the centre of inertia and simultaneous rotation of the complex around the instantaneous position of the centre of inertia in the absence of symmetry elements. (nonlinear optical phenomena)

  20. Chirality-selected phase behavior in ionic polypeptide complexes

    NASA Astrophysics Data System (ADS)

    Tirrell, Matthew

    2015-03-01

    We demonstrate that chirality determines the phase state of polyelectrolyte complexes formed from mixing dilute solutions of oppositely charged polypeptides. In these systems, the physical state of the resultant complex is determined by the combination of electrostatic and hydrogen bonding interactions. The formation of fluid complexes occurs when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with a β-sheet structure on mixing. Analogous behavior occurs in micellar cores formed from polypeptide block copolymers with polyethylene oxide, where microphase separation into discrete, self-assembled aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in systems based on polyelectrolyte complexation. Its role in these systems gives insight into polyelectrolyte complex phase behavior more broadly. This work was supported by the U.S. Department of Energy Office of Science Program in Basic Energy Sciences, Materials Sciences and Engineering Division.

  1. Phase effects in masking by harmonic complexes: Speech recognition

    PubMed Central

    Deroche, Mickael L. D.; Culling, John F.; Chatterjee, Monita

    2013-01-01

    Harmonic complexes that generate highly modulated temporal envelopes on the basilar membrane (BM) mask a tone less effectively than complexes that generate relatively flat temporal envelopes, because the non-linear active gain of the BM selectively amplifies a low-level tone in the dips of a modulated masker envelope. The present study examines a similar effect in speech recognition. Speech reception thresholds (SRTs) were measured for a voice masked by harmonic complexes with partials in sine phase (SP) or in random phase (RP). The masker’s fundamental frequency (F0) was 50, 100 or 200 Hz. SRTs were considerably lower for SP than for RP maskers at 50-Hz F0, but the two converged at 100-Hz F0, while at 200-Hz F0, SRTs were a little higher for SP than RP maskers. The results were similar whether the target voice was male or female and whether the masker’s spectral profile was flat or speech-shaped. Although listening in the masker dips has been shown to play a large role for artificial stimuli such as Schroeder-phase complexes at high levels, it contributes weakly to speech recognition in the presence of harmonic maskers with different crest factors at more moderate sound levels (65 dB SPL). PMID:24076425

  2. Using Neural Networks to Describe Complex Phase Transformation Behavior

    SciTech Connect

    Vitek, J.M.; David, S.A.

    1999-05-24

    Final microstructures can often be the end result of a complex sequence of phase transformations. Fundamental analyses may be used to model various stages of the overall behavior but they are often impractical or cumbersome when considering multicomponent systems covering a wide range of compositions. Neural network analysis may be a useful alternative method of identifying and describing phase transformation beavior. A neural network model for ferrite prediction in stainless steel welds is described. It is shown that the neural network analysis provides valuable information that accounts for alloying element interactions. It is suggested that neural network analysis may be extremely useful for analysis when more fundamental approaches are unavailable or overly burdensome.

  3. Complex PTSD and phased treatment in refugees: a debate piece

    PubMed Central

    ter Heide, F. Jackie June; Mooren, Trudy M.; Kleber, Rolf J.

    2016-01-01

    Background Asylum seekers and refugees have been claimed to be at increased risk of developing complex posttraumatic stress disorder (complex PTSD). Consequently, it has been recommended that refugees be treated with present-centred or phased treatment rather than stand-alone trauma-focused treatment. This recommendation has contributed to a clinical practice of delaying or waiving trauma-focused treatment in refugees with PTSD. Objective The aim of this debate piece is to defend two theses: (1) that complex trauma leads to complex PTSD in a minority of refugees only and (2) that trauma-focused treatment should be offered to all refugees who seek treatment for PTSD. Methods The first thesis is defended by comparing data on the prevalence of complex PTSD in refugees to those in other trauma-exposed populations, using studies derived from a systematic review. The second thesis is defended using conclusions of systematic reviews and a meta-analysis of the efficacy of psychotherapeutic treatment in refugees. Results Research shows that refugees are more likely to meet a regular PTSD diagnosis or no diagnosis than a complex PTSD diagnosis and that prevalence of complex PTSD in refugees is relatively low compared to that in survivors of childhood trauma. Effect sizes for trauma-focused treatment in refugees, especially narrative exposure therapy (NET) and culturally adapted cognitive-behaviour therapy (CA-CBT), have consistently been found to be high. Conclusions Complex PTSD in refugees should not be assumed to be present on the basis of complex traumatic experiences but should be carefully diagnosed using a validated interview. In line with treatment guidelines for PTSD, a course of trauma-focused treatment should be offered to all refugees seeking treatment for PTSD, including asylum seekers. PMID:26886486

  4. Luttinger liquid with complex forward scattering: Robustness and Berry phase

    NASA Astrophysics Data System (ADS)

    Dóra, Balázs; Moessner, Roderich

    2016-02-01

    Luttinger liquids (LLs) are one-dimensional systems with well-understood instabilities due to Umklapp or backscattering. We study a generalization of the Luttinger model, which incorporates a time reversal symmetry breaking interaction producing a complex forward scattering amplitude (g2 process). The resulting low energy state is still a LL and belongs to the family of interacting Schulz-Shastry models. Remarkably, it becomes increasingly robust against additional perturbations—for purely imaginary g2, both Umklapp and local backscattering are always irrelevant. Changing the phase of the interaction generates a nontrivial Berry phase, with a universal geometric phase difference between ground and a one boson excited state depending only on the LL parameter.

  5. Enlightening intracellular complexity of living cells with quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Martinez Torres, C.; Laperrousaz, B.; Berguiga, L.; Boyer Provera, E.; Elezgaray, J.; Nicolini, F. E.; Maguer-Satta, V.; Arneodo, A.; Argoul, F.

    2016-03-01

    The internal distribution of refractive indices (RIs) of a living cell is much more complex than usually admitted in multi-shell models. The reconstruction of RI maps from single phase images has rarely been achieved for several reasons: (i) we still have very little knowledge of the impact of internal macromolecular complexes on the local RI and (ii) phase changes produced by light propagation through the sample are mixed with diffraction effects by internal cell bodies. We propose the implementation a 2D wavelet-based contour chain detection method to distinguish internal boundaries thanks to their greatest optical path difference gradients. These contour chains correspond to the highest image phase contrast and follow the local RI inhomogeneities linked to the intracellular structural intricacy. Their statistics and spatial distribution are morphological indicators for distinguishing cells of different origins and to follow their transformation in pathologic situations. We use this method to compare non adherent blood cells from primary and laboratory culture origins, in healthy and pathological situations (chronic myelogenous leukaemia). In a second part of this presentation, we concentrate on the temporal dynamics of the phase contour chains and we discuss the spectral decomposition of their dynamics in both health and disease.

  6. Electrical switching to probe complex phases in a frustrated manganite

    NASA Astrophysics Data System (ADS)

    Asthana, Saket; Fujiwara, Kohei; Tanaka, Hidekazu

    2014-06-01

    Electrical switching was used to investigate complex phases induced by Cr-substitution in (Pr1/3Sm2/3)2/3Sr1/3MnO3. This system was expected to transform from a Type I (Mn4+/Mn3+≈3/7) to Type II (Mn4+/Mn3+≈1) manganite at critical Cr content, satisfying a virtual Mn4+/Mn3+ ratio close to unity. The phase diagram of (Pr1/3Sm2/3)2/3Sr1/3Mn0.8Cr0.2O3 including charge/spin ordered/disordered phases was probed by electrical switching. The ferromagnetic insulating phase at <~100 K, located next to the charge-ordered antiferromagnetic phase, exhibited a sudden rise in conductivity upon electric-field biasing. This resulted from the melting of charge ordering, and demonstrated the presence of a crossover regime of two coexisting magnetic orderings.

  7. Nucleic Acid-Peptide Complex Phase Controlled by DNA Hybridization

    NASA Astrophysics Data System (ADS)

    Vieregg, Jeffrey; Lueckheide, Michael; Leon, Lorraine; Marciel, Amanda; Tirrell, Matthew

    When polyanions and polycations are mixed, counterion release drives formation of polymer-rich complexes that can either be solid (precipitates) or liquid (coacervates) depending on the properties of the polyelectrolytes. These complexes are important in many fields, from encapsulation of industrial polymers to membrane-free segregation of biomolecules such as nucleic acids and proteins. Condensation of long double-stranded DNA has been studied for several decades, but comparatively little attention has been paid to the polyelectrolyte behavior of oligonucleotides. We report here studies of DNA oligonucleotides (10 - 88 nt) complexed with polylysine (10 - 100 aa). Unexpectedly, we find that the phase of the resulting complexes is controlled by the hybridization state of the nucleic acid, with double-stranded DNA forming precipitates and single-stranded DNA forming coacervates. Stability increases with polyelectrolyte length and decreases with solution salt concentration, with complexes of the longer double-stranded polymers undergoing precipitate/coacervate/soluble transitions as ionic strength is increased. Mixing coacervates formed by complementary single-stranded oligonucleotides results in precipitate formation, raising the possibility of stimulus-responsive material design.

  8. Complex quantum network geometries: Evolution and phase transitions

    NASA Astrophysics Data System (ADS)

    Bianconi, Ginestra; Rahmede, Christoph; Wu, Zhihao

    2015-08-01

    Networks are topological and geometric structures used to describe systems as different as the Internet, the brain, or the quantum structure of space-time. Here we define complex quantum network geometries, describing the underlying structure of growing simplicial 2-complexes, i.e., simplicial complexes formed by triangles. These networks are geometric networks with energies of the links that grow according to a nonequilibrium dynamics. The evolution in time of the geometric networks is a classical evolution describing a given path of a path integral defining the evolution of quantum network states. The quantum network states are characterized by quantum occupation numbers that can be mapped, respectively, to the nodes, links, and triangles incident to each link of the network. We call the geometric networks describing the evolution of quantum network states the quantum geometric networks. The quantum geometric networks have many properties common to complex networks, including small-world property, high clustering coefficient, high modularity, and scale-free degree distribution. Moreover, they can be distinguished between the Fermi-Dirac network and the Bose-Einstein network obeying, respectively, the Fermi-Dirac and Bose-Einstein statistics. We show that these networks can undergo structural phase transitions where the geometrical properties of the networks change drastically. Finally, we comment on the relation between quantum complex network geometries, spin networks, and triangulations.

  9. Generalizing the Boltzmann equation in complex phase space.

    PubMed

    Zadehgol, Abed

    2016-08-01

    In this work, a generalized form of the BGK-Boltzmann equation is proposed, where the velocity, position, and time can be represented by real or complex variables. The real representation leads to the conventional BGK-Boltzmann equation, which can recover the continuity and Navier-Stokes equations. We show that the complex representation yields a different set of equations, and it can also recover the conservation and Navier-Stokes equations, at low Mach numbers, provided that the imaginary component of the macroscopic mass can be neglected. We briefly review the Constant Speed Kinetic Model (CSKM), which was introduced in Zadehgol and Ashrafizaadeh [J. Comp. Phys. 274, 803 (2014)JCTPAH0021-999110.1016/j.jcp.2014.06.053] and Zadehgol [Phys. Rev. E 91, 063311 (2015)PLEEE81539-375510.1103/PhysRevE.91.063311]. The CSKM is then used as a basis to show that the complex-valued equilibrium distribution function of the present model can be identified with a simple singularity in the complex phase space. The virtual particles, in the present work, are concentrated on virtual "branes" which surround the computational nodes. Employing the Cauchy integral formula, it is shown that certain variations of the "branes," in the complex phase space, do not affect the local kinetic states. This property of the new model, which is referred to as the "apparent jumps" in the present work, is used to construct new models. The theoretical findings have been tested by simulating three benchmark flows. The results of the present simulations are in excellent agreement with the previous results reported by others. PMID:27627421

  10. Phase-separation models for swimming enhancement in complex fluids

    NASA Astrophysics Data System (ADS)

    Man, Yi; Lauga, Eric

    2015-08-01

    Swimming cells often have to self-propel through fluids displaying non-Newtonian rheology. While past theoretical work seems to indicate that stresses arising from complex fluids should systematically hinder low-Reynolds number locomotion, experimental observations suggest that locomotion enhancement is possible. In this paper we propose a physical mechanism for locomotion enhancement of microscopic swimmers in a complex fluid. It is based on the fact that microstructured fluids will generically phase-separate near surfaces, leading to the presence of low-viscosity layers, which promote slip and decrease viscous friction near the surface of the swimmer. We use two models to address the consequence of this phase separation: a nonzero apparent slip length for the fluid and then an explicit modeling of the change of viscosity in a thin layer near the swimmer. Considering two canonical setups for low-Reynolds number locomotion, namely the waving locomotion of a two-dimensional sheet and that of a three-dimensional filament, we show that phase-separation systematically increases the locomotion speeds, possibly by orders of magnitude. We close by confronting our predictions with recent experimental results.

  11. Phase-separation models for swimming enhancement in complex fluids.

    PubMed

    Man, Yi; Lauga, Eric

    2015-08-01

    Swimming cells often have to self-propel through fluids displaying non-Newtonian rheology. While past theoretical work seems to indicate that stresses arising from complex fluids should systematically hinder low-Reynolds number locomotion, experimental observations suggest that locomotion enhancement is possible. In this paper we propose a physical mechanism for locomotion enhancement of microscopic swimmers in a complex fluid. It is based on the fact that microstructured fluids will generically phase-separate near surfaces, leading to the presence of low-viscosity layers, which promote slip and decrease viscous friction near the surface of the swimmer. We use two models to address the consequence of this phase separation: a nonzero apparent slip length for the fluid and then an explicit modeling of the change of viscosity in a thin layer near the swimmer. Considering two canonical setups for low-Reynolds number locomotion, namely the waving locomotion of a two-dimensional sheet and that of a three-dimensional filament, we show that phase-separation systematically increases the locomotion speeds, possibly by orders of magnitude. We close by confronting our predictions with recent experimental results. PMID:26382500

  12. Quantum trajectories in complex phase space: multidimensional barrier transmission.

    PubMed

    Wyatt, Robert E; Rowland, Brad A

    2007-07-28

    The quantum Hamilton-Jacobi equation for the action function is approximately solved by propagating individual Lagrangian quantum trajectories in complex-valued phase space. Equations of motion for these trajectories are derived through use of the derivative propagation method (DPM), which leads to a hierarchy of coupled differential equations for the action function and its spatial derivatives along each trajectory. In this study, complex-valued classical trajectories (second order DPM), along which is transported quantum phase information, are used to study low energy barrier transmission for a model two-dimensional system involving either an Eckart or Gaussian barrier along the reaction coordinate coupled to a harmonic oscillator. The arrival time for trajectories to reach the transmitted (product) region is studied. Trajectories launched from an "equal arrival time surface," defined as an isochrone, all reach the real-valued subspace in the transmitted region at the same time. The Rutherford-type diffraction of trajectories around poles in the complex extended Eckart potential energy surface is described. For thin barriers, these poles are close to the real axis and present problems for computing the transmitted density. In contrast, for the Gaussian barrier or the thick Eckart barrier where the poles are further from the real axis, smooth transmitted densities are obtained. Results obtained using higher-order quantum trajectories (third order DPM) are described for both thick and thin barriers, and some issues that arise for thin barriers are examined. PMID:17672677

  13. Phase shifting and the beating of complex waves

    NASA Astrophysics Data System (ADS)

    Keeports, David

    2011-03-01

    At the introductory level, the demonstration and analysis of sound beating is usually limited to the superposition of two purely sinusoidal waves with equal amplitudes and very similar frequencies. Under such conditions, an observer hears the periodic variation of the loudness of a sound with an unchanging timbre. On the other hand, when complex waves with very similar frequencies are superimposed, each harmonic beats with a frequency proportional to the frequency of the harmonic. Consequently, the resulting sound exhibits a subtle variation of timbre with time. This article extends the normal introductory discussion of beating and explains why electronic phase shifters, devices familiar to many musicians, can produce the sound of beating complex waves.

  14. Nonlinearity compensation and complex-to-phase conversion of complex incoherent digital holograms for optical reconstruction.

    PubMed

    Liu, Jung-Ping; Wang, Sheng-Yen; Tsang, P W M; Poon, Ting-Chung

    2016-06-27

    Incoherent digital holography (IDH) can be realized by optical scanning holography or self-interference incoherent holography. Although IDH can exhibit high quality reconstruction due to its inherently speckle-free property, direct display of an incoherent hologram is a challenge because of its amplitude nonlinearity and the demand of complex modulation. In this paper we propose to compensate the amplitude nonlinearity at the object plane, and use bidirectional error-diffusion method to convert the complex-type incoherent Fresnel hologram to a phase-only Fresnel hologram for display. A spatial light modulator is used to reconstruct the phase-only hologram optically to demonstrate the validity of our proposed method. PMID:27410610

  15. Modelling of phase diagrams of nanoalloys with complex metallic phases: application to Ni-Sn.

    PubMed

    Kroupa, A; Káňa, T; Buršík, J; Zemanová, A; Šob, M

    2015-11-14

    A method for modelling of size-dependent phase diagrams was developed by combining the semiempirical CALPHAD method and ab initio calculations of surface stresses for intermetallic phases. A novel approach was devised for the calculation of surface energy, free of systematic errors from the selection of different parameters of the software (e.g. number of the k-points) and for handling layered structures and off-stoichiometric slabs. Our approach allows the determination of complex size-dependent phase diagrams of systems with intermetallic phases, which was not possible up to now. The method was verified for the modelling of the phase diagram of the Ni-Sn system and basic comparison with rare experimental results was shown. There is reasonable agreement between the calculated and experimental results. The modelling of size-dependent phase diagrams of real systems allows the prediction of phase equilibria existing in nanosystems and possible changes in material properties. There is a need for such knowledge and the existence of reliable data for simpler systems is crucial for further application of this approach. This should motivate future experimental work. PMID:25824490

  16. Complex network analysis of phase dynamics underlying oil-water two-phase flows.

    PubMed

    Gao, Zhong-Ke; Zhang, Shan-Shan; Cai, Qing; Yang, Yu-Xuan; Jin, Ning-De

    2016-01-01

    Characterizing the complicated flow behaviors arising from high water cut and low velocity oil-water flows is an important problem of significant challenge. We design a high-speed cycle motivation conductance sensor and carry out experiments for measuring the local flow information from different oil-in-water flow patterns. We first use multivariate time-frequency analysis to probe the typical features of three flow patterns from the perspective of energy and frequency. Then we infer complex networks from multi-channel measurements in terms of phase lag index, aiming to uncovering the phase dynamics governing the transition and evolution of different oil-in-water flow patterns. In particular, we employ spectral radius and weighted clustering coefficient entropy to characterize the derived unweighted and weighted networks and the results indicate that our approach yields quantitative insights into the phase dynamics underlying the high water cut and low velocity oil-water flows. PMID:27306101

  17. Complex network analysis of phase dynamics underlying oil-water two-phase flows

    NASA Astrophysics Data System (ADS)

    Gao, Zhong-Ke; Zhang, Shan-Shan; Cai, Qing; Yang, Yu-Xuan; Jin, Ning-De

    2016-06-01

    Characterizing the complicated flow behaviors arising from high water cut and low velocity oil-water flows is an important problem of significant challenge. We design a high-speed cycle motivation conductance sensor and carry out experiments for measuring the local flow information from different oil-in-water flow patterns. We first use multivariate time-frequency analysis to probe the typical features of three flow patterns from the perspective of energy and frequency. Then we infer complex networks from multi-channel measurements in terms of phase lag index, aiming to uncovering the phase dynamics governing the transition and evolution of different oil-in-water flow patterns. In particular, we employ spectral radius and weighted clustering coefficient entropy to characterize the derived unweighted and weighted networks and the results indicate that our approach yields quantitative insights into the phase dynamics underlying the high water cut and low velocity oil-water flows.

  18. Complex network analysis of phase dynamics underlying oil-water two-phase flows

    PubMed Central

    Gao, Zhong-Ke; Zhang, Shan-Shan; Cai, Qing; Yang, Yu-Xuan; Jin, Ning-De

    2016-01-01

    Characterizing the complicated flow behaviors arising from high water cut and low velocity oil-water flows is an important problem of significant challenge. We design a high-speed cycle motivation conductance sensor and carry out experiments for measuring the local flow information from different oil-in-water flow patterns. We first use multivariate time-frequency analysis to probe the typical features of three flow patterns from the perspective of energy and frequency. Then we infer complex networks from multi-channel measurements in terms of phase lag index, aiming to uncovering the phase dynamics governing the transition and evolution of different oil-in-water flow patterns. In particular, we employ spectral radius and weighted clustering coefficient entropy to characterize the derived unweighted and weighted networks and the results indicate that our approach yields quantitative insights into the phase dynamics underlying the high water cut and low velocity oil-water flows. PMID:27306101

  19. Strain rate behaviour of multi-phase and complex-phase steels for automotive applications

    NASA Astrophysics Data System (ADS)

    Cadoni, E.; Singh, N. K.; Singha, M. K.; Gupta, N. K.

    2012-08-01

    A combined study on the mechanical behaviour of multi-phase 800 high yield strength steel (MP800HY) and complex-phase 800 steel (CP800) is carried out under tensile loads in the strain rate range from 0.001s-1 to 750s-1. Quasi-static (0.001s-1) tests are performed on electromechanical machine, whereas, medium (5s-1 and 25s-1) and high strain rate (250s-1, 500s-1 and 750s-1) experiments are conducted on hydro-pneumatic machine (HPM) and modified Hopkinson bar (MHB) setup respectively. The thermal softening behaviors of the materials are investigated at quasi-static condition and the materials' m-parameters of the existing Johnson-Cook model are imposed in authors' previous work. Thereafter, the predicted flow stress by Johnson-Cook model has been compared with the experimental results.

  20. A phased approach to enable hybrid simulation of complex structures

    NASA Astrophysics Data System (ADS)

    Spencer, Billie F.; Chang, Chia-Ming; Frankie, Thomas M.; Kuchma, Daniel A.; Silva, Pedro F.; Abdelnaby, Adel E.

    2014-08-01

    Hybrid simulation has been shown to be a cost-effective approach for assessing the seismic performance of structures. In hybrid simulation, critical parts of a structure are physically tested, while the remaining portions of the system are concurrently simulated computationally, typically using a finite element model. This combination is realized through a numerical time-integration scheme, which allows for investigation of full system-level responses of a structure in a cost-effective manner. However, conducting hybrid simulation of complex structures within large-scale testing facilities presents significant challenges. For example, the chosen modeling scheme may create numerical inaccuracies or even result in unstable simulations; the displacement and force capacity of the experimental system can be exceeded; and a hybrid test may be terminated due to poor communication between modules (e.g., loading controllers, data acquisition systems, simulation coordinator). These problems can cause the simulation to stop suddenly, and in some cases can even result in damage to the experimental specimens; the end result can be failure of the entire experiment. This study proposes a phased approach to hybrid simulation that can validate all of the hybrid simulation components and ensure the integrity large-scale hybrid simulation. In this approach, a series of hybrid simulations employing numerical components and small-scale experimental components are examined to establish this preparedness for the large-scale experiment. This validation program is incorporated into an existing, mature hybrid simulation framework, which is currently utilized in the Multi-Axial Full-Scale Sub-Structuring Testing and Simulation (MUST-SIM) facility of the George E. Brown Network for Earthquake Engineering Simulation (NEES) equipment site at the University of Illinois at Urbana-Champaign. A hybrid simulation of a four-span curved bridge is presented as an example, in which three piers are

  1. Phase Transitions in the Quadratic Contact Process on Complex Networks

    NASA Astrophysics Data System (ADS)

    Varghese, Chris; Durrett, Rick

    2013-03-01

    The quadratic contact process (QCP) is a natural extension of the well studied linear contact process where a single infected (1) individual can infect a susceptible (0) neighbor and infected individuals are allowed to recover (1 --> 0). In the QCP, a combination of two 1's is required to effect a 0 --> 1 change. We extend the study of the QCP, which so far has been limited to lattices, to complex networks as a model for the change in a population via sexual reproduction and death. We define two versions of the QCP - vertex centered (VQCP) and edge centered (EQCP) with birth events 1 - 0 - 1 --> 1 - 1 - 1 and 1 - 1 - 0 --> 1 - 1 - 1 respectively, where ` -' represents an edge. We investigate the effects of network topology by considering the QCP on regular, Erdős-Rényi and power law random graphs. We perform mean field calculations as well as simulations to find the steady state fraction of occupied vertices as a function of the birth rate. We find that on the homogeneous graphs (regular and Erdős-Rényi) there is a discontinuous phase transition with a region of bistability, whereas on the heavy tailed power law graph, the transition is continuous. The critical birth rate is found to be positive in the former but zero in the latter.

  2. Complex interfaces in "phase-change" contrast agents.

    PubMed

    Capece, Sabrina; Domenici, Fabio; Brasili, Francesco; Oddo, Letizia; Cerroni, Barbara; Bedini, Angelico; Bordi, Federico; Chiessi, Ester; Paradossi, Gaio

    2016-03-28

    In this paper we report on the study of the interface of hybrid shell droplets encapsulating decafluoropentane (DFP), which exhibit interesting potentialities for ultrasound (US) imaging. The fabrication of the droplets is based on the deposition of a dextran methacrylate layer onto the surface of surfactants. The droplets have been stabilized against coalescence by UV curing, introducing crosslinks in the polymer layer and transforming the shell into an elastomeric membrane with a thickness of about 300 nm with viscoelastic behaviour. US irradiation induces the evaporation of the DFP core of the droplets transforming the particles into microbubbles (MBs). The presence of a robust crosslinked polymer shell introduces an unusual stability of the droplets also during the core phase transition and allows the recovery of the initial droplet state after a few minutes from switching off US. The interfacial tension of the droplets has been investigated by two approaches, the pendant drop method and an indirect method, based on the determination of the liquid ↔ gas transition point of DFP confined in the droplet core. The re-condensation process has been followed by capturing images of single MBs by confocal microscopy. The time evolution of MB relaxation to droplets was analysed in terms of a modified Church model to account for the structural complexity of the MB shell, i.e. a crosslinked polymer layer over a layer of surfactants. In this way the microrheology parameters of the shell were determined. In a previous paper (Chem. Commun., 2013, 49, 5763-5765) we showed that these systems could be used as ultrasound contrast agents (UCAs). In this work we substantiate this view assessing some key features offered by the viscoelastic nature of the droplet shell. PMID:26931337

  3. Carbonate Complexation of Mn2+ in Aqueous Phase

    PubMed Central

    Dasgupta, Jyotishman; Tyryshkin, Alexei M.; Kozlov, Yuri N.; Klimov, Vyacheslav V.; Dismukes, G. Charles

    2008-01-01

    The chemical speciation of Mn2+ within cells is critical for its transport, availability and redox properties. Herein we investigate the redox behavior and complexation equilibria of Mn2+ in aqueous solutions of bicarbonate by voltametry and electron paramagnetic resonance (EPR) spectroscopy, and discuss the implications for the uptake of Mn2+ by mangano-cluster enzymes like photosystem II (PSII). Both the electrochemical reduction of Mn2+ to Mn0 at an Hg electrode and EPR (in the absence of a polarizing electrode), revealed formation of 1:1 and 1:2 Mn-(bi)carbonate complexes as a function of Mn2+ and bicarbonate concentrations. Pulsed EPR spectroscopy, including ENDOR, ESEEM and 2D-HYSCORE, were used to probe the hyperfine couplings to 1H and 13C nuclei of the ligand(s) bound to Mn2+. For the 1:2 complex the complete 13C hyperfine tensor for one of the (bi)carbonate ligands was determined and it was established that this ligand coordinates to Mn2+ in bidentate mode with 13C-Mn distance of 2.85 ± 0.1 Å. The second (bi)carbonate ligand in the 1:2 complex coordinates possibly in monodentate mode, which is structurally less defined, and its 13C signal is broad and unobservable. 1H ENDOR reveals that 1-2 water ligands are lost upon binding of one bicarbonate ion in the 1:1 complex while 3-4 water ligands are lost upon forming the 1:2 complex. Thus, we deduce that the dominant species above 0.1 M bicarbonate concentration is the 1:2 complex, [Mn(CO3)(HCO3)(OH2)3]-. PMID:16526753

  4. Aqueous Gemini Surfactant Self-Assembly into Complex Lyotropic Phases

    NASA Astrophysics Data System (ADS)

    Mahanthappa, Mahesh; Sorenson, Gregory

    2012-02-01

    In spite of the potentially wide-ranging applications of aqueous bicontinuous lyotropic liquid crystals (LLCs), the discovery of amphiphiles that reliably form these non-constant mean curvature morphologies over large phase windows remains largely serendipitous. Recent work has established that cationic gemini surfactants exhibit a pronounced tendency to form bicontinuous cubic (e.g. gyroid) phases as compared to their parent single-tail amphiphiles. The universality of this phenomenon in other surfactant systems remains untested. In this paper, we will report the aqueous LLC phase behavior of a new class of anionic gemini surfactants derived from long chain carboxylic acids. Our studies show that these new surfactants favor the formation of non-constant mean curvature gyroid and primitive (``Plumber's Nightmare'') structures over amphiphile concentration windows up to 20 wt% wide. Based on these observations, we will discuss insights gained into the delicate force balance governing the self-assembly of these surfactants into aqueous bicontinuous LLCs.

  5. Accurate thermodynamic properties of gas phase hydrogen bonded complexes.

    PubMed

    Hansen, Anne S; Maroun, Zeina; Mackeprang, Kasper; Frandsen, Benjamin N; Kjaergaard, Henrik G

    2016-08-24

    We have measured the infrared spectra of ethanol·dimethylamine and methanol·dimethylamine complexes in the 299-374 K temperature range, and have determined the enthalpy of complex formation (ΔH) to be -31.1 ± 2 and -29.5 ± 2 kJ mol(-1), respectively. The corresponding values of the Gibbs free energy (ΔG) are determined from the experimental integrated absorbance and a calculated oscillator strength of the OH-stretching vibrational transition to be 4.1 ± 0.3 and 3.9 ± 0.3 kJ mol(-1) at 302 and 300 K, respectively. The entropy, ΔS is determined from the values of ΔH and ΔG to be -117 ± 7 and -111 ± 10 J (mol K)(-1) for the ethanol·dimethylamine and methanol·dimethylamine complexes, respectively. The determined ΔH, ΔG and ΔS values of the two complexes are similar, as expected by the similarity to their donor molecules ethanol and methanol. Values of ΔH, ΔG and ΔS in chemical reactions are often obtained from quantum chemical calculations. However, these calculated values have limited accuracy and large variations are found using different methods. The accuracy of the present ΔH, ΔG and ΔS values is such that the benchmarking of theoretical methods is possible. PMID:27523902

  6. Removal of complex-conjugate ambiguity in SDOCT by using phase shiftings

    NASA Astrophysics Data System (ADS)

    Cai, Wenyuan; Jiang, Zhuqing; Huang, Haochong

    2012-12-01

    The three-step or many steps phase shifting method is usually employed to resolve the complex-conjugate ambiguity in Spectral-domain optical coherence tomography (SD-OCT). However it reduces the image quality and also the imaging speed is slow. In this paper two steps phase-shifting is used in digital image processing to resolve the complex-conjugate ambiguity and improves the quality of reconstructed image in SD-OCT. In the two-step phase shifting method the phase shifting operation is used only once which simplified the experiment and also the effect of relative error in SD-OCT on image quality is eliminated.

  7. Statistical energy analysis of complex structures, phase 2

    NASA Technical Reports Server (NTRS)

    Trudell, R. W.; Yano, L. I.

    1980-01-01

    A method for estimating the structural vibration properties of complex systems in high frequency environments was investigated. The structure analyzed was the Materials Experiment Assembly, (MEA), which is a portion of the OST-2A payload for the space transportation system. Statistical energy analysis (SEA) techniques were used to model the structure and predict the structural element response to acoustic excitation. A comparison of the intial response predictions and measured acoustic test data is presented. The conclusions indicate that: the SEA predicted the response of primary structure to acoustic excitation over a wide range of frequencies; and the contribution of mechanically induced random vibration to the total MEA is not significant.

  8. MOLECULAR SIMULATION OF PHASE EQUILIBRIA FOR COMPLEX FLUIDS

    SciTech Connect

    Athanassios Z. Panagiotopoulos

    2009-09-09

    The general area of this project was the development and application of novel molecular simulation methods for prediction of thermodynamic and structural properties of complex polymeric, surfactant and ionic fluids. Over this project period, we have made considerable progress in developing novel algorithms to meet the computational challenges presented by the strong or long-range interactions in these systems and have generated data for well-defined mod-els that can be used to test theories and compare to experimental data. Overall, 42 archival papers and many invited and contributed presentations and lectures have been based on work supported by this project. 6 PhD, 1 M.S. and 2 postdoctoral students have been associated with this work, as listed in the body of the report.

  9. Acute phase proteins in cattle after exposure to complex stress.

    PubMed

    Lomborg, S R; Nielsen, L R; Heegaard, P M H; Jacobsen, S

    2008-10-01

    Stressors such as weaning, mixing and transportation have been shown to lead to increased blood concentrations of acute phase proteins (APP), including serum amyloid A (SAA) and haptoglobin, in calves. This study was therefore undertaken to assess whether SAA and haptoglobin levels in blood mirror stress in adult cattle. Six clinically healthy Holstein cows and two Holstein heifers were transported for four to six hours to a research facility, where each animal was housed in solitary tie stalls. Blood samples for evaluation of leukocyte counts and serum SAA and haptoglobin concentrations were obtained before (0-sample) and at 8, 24 and 48 hours after the start of transportation. Upon arrival the animals gave the impression of being anxious, and they appeared to have difficulty coping with isolation and with being tied on the slippery floors of the research stable. Serum concentrations of SAA and haptoglobin increased significantly in response to the stressors (P < 0.01 and 0.05 at 48 hours, respectively). Additionally, the animals had transient neutrophilia at 8 and 24 hours (P < 0.05). In conclusion, the results of the study suggest that SAA and haptoglobin may serve as markers of stress in adult cattle. PMID:18461465

  10. Topological feature and phase structure of QCD at complex chemical potential

    NASA Astrophysics Data System (ADS)

    Kashiwa, Kouji; Ohnishi, Akira

    2015-11-01

    The pseudo-critical temperature of the confinement-deconfinement transition and the phase transition surface are investigated by using the complex chemical potential. We can interpret the imaginary chemical potential as the Aharonov-Bohm phase, then the analogy of the topological order suggests that the Roberge-Weiss endpoint would define the pseudo-critical temperature. The behavior of the Roberge-Weiss endpoint at small real quark chemical potential is investigated with the perturbative expansion. The expected QCD phase diagram at complex chemical potential is presented.

  11. Acoustic radiation force expressed using complex phase shifts and momentum-transfer cross sections.

    PubMed

    Zhang, Likun; Marston, Philip L

    2016-08-01

    Acoustic radiation force is expressed using complex phase shifts of partial wave scattering functions and the momentum-transfer cross section, herein incorporated into acoustics from quantum mechanisms. Imaginary parts of the phase shifts represent dissipation in the object and/or in the boundary layer adjacent to the object. The formula simplifies the force as summation of functions of complex phase shifts of adjacent partial waves involving differences of real parts and sums of imaginary parts, providing an efficient way of exploring the force parameter-space. The formula for the force is proportional to a generalized momentum-transfer cross section for plane waves and no dissipation. PMID:27586777

  12. Topological phase transition of a fractal spin system: The relevance of the network complexity

    NASA Astrophysics Data System (ADS)

    Torres, Felipe; Rogan, José; Kiwi, Miguel; Valdivia, Juan Alejandro

    2016-05-01

    A new type of collective excitations, due to the topology of a complex random network that can be characterized by a fractal dimension DF, is investigated. We show analytically that these excitations generate phase transitions due to the non-periodic topology of the DF > 1 complex network. An Ising system, with long range interactions, is studied in detail to support the claim. The analytic treatment is possible because the evaluation of the partition function can be decomposed into closed factor loops, in spite of the architectural complexity. The removal of the infrared divergences leads to an unconventional phase transition, with spin correlations that are robust against thermal fluctuations.

  13. The phase delay and its complex time: From stationary states up to wave packets

    SciTech Connect

    Grossel, Ph.

    2013-03-15

    Complex time is often invoked about tunneling effect where the classical phase delay is completed with a crucial filter effect. Usually the complex times are obtained by considering the flux-flux correlation function, but this can be obtained by a very simple approach using the search of the maximum of the generalized complex phase function, including the amplitude of the wave function. Various aspects of the phase delay are presented in the case of wave packets impinging on simple or resonant quantum barriers. Formal links with the classical mechanics give birth to quasi-trajectories of the quantum particle, totally compatible with the quantum mechanics. - Highlights: Black-Right-Pointing-Pointer The stationary phase method is extended in including the variations of the spectra. Black-Right-Pointing-Pointer The complex phase delay leads to a complex trajectory inside and out-side the barrier. Black-Right-Pointing-Pointer Examples of quasi-trajectories are given in case of different quantum barriers. Black-Right-Pointing-Pointer Phase delays are specified for resonant tunneling or above-barrier wave-packets. Black-Right-Pointing-Pointer The coherence between the quasi-trajectories and quantum mechanics is shown.

  14. Induction of phase 3 of the migrating motor complex in human small intestine by trimebutine.

    PubMed

    Chaussade, S; Grandjouan, S; Couturier, D; Thierman-Duffaud, D; Henry, J F

    1987-01-01

    The effects of trimebutine, a drug used in the treatment of various gastrointestinal motility disorders, have been investigated fed and fasted healthy subjects. Duodenojejunal motility was recorded manometrically with a 4-lumen probe. Trimebutine 50 or 100 mg was injected i.v. 3 or 25 min after observing a spontaneous Phase 3 complex in the fasted state. Other experiments were done in the postprandial state and after intravenous naloxone 0.8 mg. In the fasted state, trimebutine 100 mg, injected 25 min after a spontaneous Phase 3 complex consistently induced a premature Phase 3 complex. The mean duration of the migrating motor complex cycle decreased from 86.4 +/- 10.8 min to 32.5 +/- 1.0 min. Trimebutine 50 mg injected 3 and 25 min after a spontaneous Phase 3 complex did not significantly modify the periodicity of the migrating motor complex. Trimebutine 100 mg initiated Phase 3-like activity in the post-prandial state. Previous intravenous administration of naloxone 0.8 mg (Narcan) suppressed the stimulatory action of TMB. Thus, trimebutine is able to modify the motility pattern in the small intestine of man, possibly by acting at opioid receptors. PMID:2820749

  15. Supramolecular reactivity in the gas phase: investigating the intrinsic properties of non-covalent complexes.

    PubMed

    Cera, Luca; Schalley, Christoph A

    2014-03-21

    The high vacuum inside a mass spectrometer offers unique conditions to broaden our view on the reactivity of supramolecules. Because dynamic exchange processes between complexes are efficiently suppressed, the intrinsic and intramolecular reactivity of the complexes of interest is observed. Besides this, the significantly higher strength of non-covalent interactions in the absence of competing solvent allows processes to occur that are unable to compete in solution. The present review highlights a series of examples illustrating different aspects of supramolecular gas-phase reactivity ranging from the dissociation and formation of covalent bonds in non-covalent complexes through the reactivity in the restricted inner phase of container molecules and step-by-step mechanistic studies of organocatalytic reaction cycles to cage contraction reactions, processes induced by electron capture, and finally dynamic molecular motion within non-covalent complexes as unravelled by hydrogen-deuterium exchange processes performed in the gas phase. PMID:24435245

  16. Dynamic equilibrium dissolution of complex nonaqueous phase liquid mixtures into the aqueous phase.

    PubMed

    Schluep, Mathias; Gälli, René; Imboden, Dieter M; Zeyer, Josef

    2002-07-01

    Human health risks posed by hazardous substances seeping from a pool of nonaqueous phase liquids (NAPLs) into groundwater change over time because the more soluble compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) dissolve faster into the aqueous phase than less soluble compounds such as polycyclic aromatic hydrocarbons (PAH). Long-term dissolution from diesel fuel into the aqueous phase was determined experimentally in a continuous flow-through system using the slow-stirring method. The data obtained are interpreted using a dynamic equilibrium dissolution model based on Raoult's law. The predicted temporal development of aqueous concentrations are in good agreement with the experimental results. When a compound in the NAPL approaches complete depletion, a tailing behavior is observed, which is assigned to nonequilibrium effects, such as mass transfer limitations in the NAPL phase. The model predicted an increase of the mean molar mass of the diesel fuel of 1.5% over the entire experimental period. It should be noted that, if the dissolution process were to proceed further, the change in the mean molar mass could become significant and render the simple model inaccurate. Yet the simple model supports the assessment of initial action after a contamination event as well as the planning of long-term remedial strategies. PMID:12109733

  17. A REVIEW OF THE EARLY DEVELOPMENT OF THE THERMODYNAMICS OF THE COMPLEX COACERVATION PHASE SEPARATION

    PubMed Central

    Veis, Arthur

    2011-01-01

    Coacervation was defined as the phenomenon in which a colloidal dispersion separated into colloid-rich (the coacervate), and colloid-poor phases, both with the same solvent. Complex coacervation covered the situation in which a mixture of two polymeric polyions with opposite charge separated into liquid dilute and concentrated phases, in the same solvent, with both phases, at equilibrium, containing both polyions. Voorn and Overbeek provided the first theoretical analysis of complex coacervation by applying Flory-Huggins polymer statistics to model the random mixing of the polyions and their counter ions in solution, assuming completely random mixing of the polyions in each phase, with the electrostatic free energy, ΔGelect, providing the driving force. However, experimentally complete randomness does not apply: polyion size, heterogeneity, chain stiffness and charge density (σ) all affect the equilibrium phase separation and phase concentrations. Moreover, in pauci-disperse systems multiple phases are often observed. As an alternative, Veis and Aranyi proposed the formation of charge paired Symmetrical Aggregates (SA) as an initial step, followed by phase separation driven by the interaction parameter, χ23, combining both entropy and enthalpy factors other than the ΔGelect electrostatic term. This two stage path to equilibrium phase separation allows for understanding and quantifying and modeling the diverse aggregates produced by interactions between polyampholyte molecules of different charge density, σ, and intrinsic polyion structure. PMID:21377640

  18. Single Sublattice Endotaxial Phase Separation Driven by Charge Frustration in a Complex Oxide

    PubMed Central

    2013-01-01

    Complex transition-metal oxides are important functional materials in areas such as energy and information storage. The cubic ABO3 perovskite is an archetypal example of this class, formed by the occupation of small octahedral B-sites within an AO3 network defined by larger A cations. We show that introduction of chemically mismatched octahedral cations into a cubic perovskite oxide parent phase modifies structure and composition beyond the unit cell length scale on the B sublattice alone. This affords an endotaxial nanocomposite of two cubic perovskite phases with distinct properties. These locally B-site cation-ordered and -disordered phases share a single AO3 network and have enhanced stability against the formation of a competing hexagonal structure over the single-phase parent. Synergic integration of the distinct properties of these phases by the coherent interfaces of the composite produces solid oxide fuel cell cathode performance superior to that expected from the component phases in isolation. PMID:23750709

  19. Defect-mediated spatial complexity and chaos in a phase-conjugate resonator

    NASA Technical Reports Server (NTRS)

    Indebetouw, Guy; Liu, Siuying R.

    1992-01-01

    We have studied the spatiotemporal dynamics of a phase-conjugate resonator. The cavity Fresnel number is used to vary the degree of transverse confinement of the system. The generation and subsequent motion of the phase defects in the wave front are seen to mediate the system's dynamics. The number of defects and the complexity of their motion increases as the confinement is relaxed, leading the system through a sequence of bifurcations and eventually to chaos.

  20. Phase transformations of hydrocarbon accumulations in the Upper Cretaceous complex of the Northeast Caucasus

    SciTech Connect

    Reznikov, A.N.; Yaroshenko, A.A.

    1982-10-01

    The geologic structure and development of the Northeast Caucasus has produced a complex distribution of hydrocarbons in different phases throughout Upper Cretaceous deposits. A comprehensive study of the thermobaric conditions in the region are presented so that the patterns of hydrocarbon phase transformations can be identified. In addition the maturation of the geologic formations in the area that led to the oil formation is discussed. (JMT)

  1. Complex phase diagram of Ba1 -xNaxFe2As2 : A multitude of phases striving for the electronic entropy

    NASA Astrophysics Data System (ADS)

    Wang, L.; Hardy, F.; Böhmer, A. E.; Wolf, T.; Schweiss, P.; Meingast, C.

    2016-01-01

    The low-temperature electronic phase diagram of Ba1 -xNaxFe2As2 , obtained using high-resolution thermal-expansion and specific-heat measurements, is shown to be considerably more complex than previously reported, containing nine different phases. Besides the magnetic C2 and reentrant C4 phases, we find evidence for an additional, presumably magnetic, phase below the usual spin-density-wave transition, as well as a possible incommensurate magnetic phase. All these phases coexist and compete with superconductivity, which is particularly strongly suppressed by the C4-magnetic phase due to a strong reduction of the electronic entropy available for pairing in this phase.

  2. Complex phase diagram of Ba1-xNaxFe2As2: a multitude of phases striving for the electronic entropy

    NASA Astrophysics Data System (ADS)

    Meingast, Christoph; Wang, Liran; Hardy, Frederic; Boehmer, Anna; Schweiss, Peter; Wolf, Thomas

    The low-temperature electronic phase diagram of Ba1-NaxFe2As2, obtained using high-resolution thermal-expansion and specific-heat measurements, is shown to be considerably more complex than previously reported, containing nine different phases. Besides the magnetic C2 and reentrant C4 phases, we find evidence for an additional, presumably magnetic, phase below the usual SDW transition, as well as a possible incommensurate magnetic phase. All these phases coexist and compete with superconductivity, which is particularly strongly suppressed by the C4-magnetic phase due to a strong reduction of the electronic entropy available for pairing in this phase.

  3. Temperature evolution of nickel sulphide phases from thiourea complex and their exchange bias effect

    SciTech Connect

    Kumar, Nitesh; Raman, N.; Sundaresan, A.

    2013-12-15

    Considering the very complex phase diagram of nickel sulphide, it is quite challenging to stabilize pure phases from a single precursor. Here, we obtain nanoparticles of various phases of nickel sulphide by decomposing nickel–thiourea complex at different temperatures. The first phase in the evolution is the one with the maximum sulphur content, namely, NiS{sub 2} nanoparticles obtained at 400 °C. As the temperature is increased, nanoparticles of phases with lesser sulphur content, NiS (600 °C) and Ni{sub 3}S{sub 2} (800 °C) are formed. NiS{sub 2} nanoparticles exhibit weak ferromagnetic transition at 30 K and show a large exchange bias at 2 K. NiS nanoparticles are antiferromagnetic and show relatively smaller exchange bias effect. On the other hand, Ni{sub 3}S{sub 2} nanoparticles exhibit very weak temperature dependent magnetization. Electrical measurements show that both NiS{sub 2} and NiS are semiconductors whereas Ni{sub 3}S{sub 2} is a metal. - Graphical abstract: Pure phases of NiS{sub 2}, NiS and Ni{sub 3}S{sub 2} have been obtained by thermal decomposition of nickel–thiourea complex wherein, NiS{sub 2} nanoparticles exhibit remarkable exchange bias effect at 2 K. - Highlights: • NiS{sub 2}, NiS and Ni{sub 3}S{sub 2} nanoparticles are obtained by thermal decomposition of nickel–thiourea complex at different temperatures. • As the temperature is increased, nickel sulphide phase with lesser sulphur content is obtained. • NiS{sub 2} nanoparticles show good exchange bias property which can be explained by antiferromagnetic core and ferromagnetic shell model. • NiS{sub 2} and NiS are semiconducting while Ni{sub 3}S{sub 2} shows metallic behavior.

  4. On the phase diagram of reentrant condensation in polyelectrolyte-liposome complexation

    NASA Astrophysics Data System (ADS)

    Sennato, S.; Bordi, F.; Cametti, C.

    2004-09-01

    Complexation of polyions with oppositely charged spherical liposomes has been investigated by means of dynamic light scattering measurements and a well-defined reentrant condensation has been observed. The phase diagram of charge inversion, recently derived [T. T. Nguyen and B. I. Shklovskii, J. Chem. Phys. 115, 7298 (2001)] for the complexation of DNA with charged spherical macroions, has been employed in order to define the boundaries of the region where polyion-liposome complexes begin to condense, forming larger aggregates, and where aggregates dissolve again, towards isolated polyion-coated-liposome complexes. A reasonable good agreement is observed in the case of complexes formed by negatively charged polyacrylate sodium salt polyions and liposomes built up by cationic lipids (dioleoyltrimethylammoniumpropane), in an extended liposome concentration range.

  5. Phase Transitions in Development of Writing Fluency from a Complex Dynamic Systems Perspective

    ERIC Educational Resources Information Center

    Baba, Kyoko; Nitta, Ryo

    2014-01-01

    This study explored patterns in L2 writing development by focusing on one of the linguistic features of texts (fluency) from a complex dynamic systems perspective. It investigated whether two English-as-a-foreign-language university students would experience discontinuous change (phase transition) in their writing fluency through repetition of a…

  6. Complex dark-field contrast in grating-based x-ray phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Tang, Xiangyang

    2015-03-01

    Without assuming that the sub-pixel microstructures of an object to be imaged distribute in space randomly, we investigate the influence of the object's microstructures on grating-based x-ray phase contrast imaging. Our theoretical analysis and 3D computer simulation study based on the paraxial Fresnel-Kirchhoff theory show that the existing dark-field contrast can be generalized into a complex dark-field contrast in a way such that its imaginary part quantifies the effect of the object's sub-pixel microstructures on the phase of intensity oscillations. A method based on the phase-attenuation duality that holds for soft tissues to be imaged at high x-ray energies is proposed to retrieve the imaginary part of the complex dark-field contrast for imaging. In comparison to the existing dark-field contrast, the imaginary part of complex dark-field contrast exhibits significantly stronger selectivity on the shape of the object's sub-pixel microstructures. Thus the x-ray imaging corresponding to the imaginary part of complex dark-field contrast can provide additional and complementary information to that corresponding to the attenuation contrast, phase contrast and the existing dark-field contrast.

  7. Negative results in phase III trials of complex interventions: cause for concern or just good science?

    PubMed

    Crawford, Mike J; Barnicot, Kirsten; Patterson, Sue; Gold, Christian

    2016-07-01

    Not all interventions that show promise in exploratory trials will be supported in phase III studies. But the high failure rate in recent trials of complex mental health interventions is a concern. Proper consideration of trial processes and greater use of adaptive trial designs could ensure better use of available resources. PMID:27369475

  8. Structural infection and anomalous phase sequences in complex oxides prepared from nanodispersed components

    SciTech Connect

    Shmytko, I. M. Strukova, G. K.; Kudrenko, E. A.

    2006-12-15

    The complex oxides prepared by solid-phase synthesis from nanoscopic components are studied using X-ray diffraction. It is demonstrated that the use of nanoscopic components in the solid-phase synthesis of lutetium borate LuBO{sub 3} and europium molybdate Eu{sub 2}(MoO{sub 4}){sub 3} leads to anomalous sequences of phase transformations in these compounds: the vaterite {sup {yields}} calcite {r_reversible} vaterite sequence for LuBO{sub 3} and the {beta} {sup {yields}} {alpha} {r_reversible} {beta} sequence for Eu{sub 2}(MoO{sub 4}){sub 3} are observed instead of the previously known sequences, namely, the calcite {r_reversible} vaterite sequence for LuBO{sub 3} and the {alpha} {r_reversible} {beta} sequence for Eu{sub 2}(MoO{sub 4}){sub 3}. The revealed anomalous sequences do not depend on the procedure used for preparing reactants and are determined by the nanoscopic sizes of the initial components. It is found that microscopic additions of a number of simple oxides can suppress the kinetics of solid-phase synthesis of particular complex oxides and initiate the formation of new phases in the synthesis of other complex oxides (the so-called structural infection effect)

  9. Full range complex spectral domain optical coherence tomography without additional phase shifters.

    PubMed

    Baumann, Bernhard; Pircher, Michael; Götzinger, Erich; Hitzenberger, Christoph K

    2007-10-01

    We demonstrate a new full range complex spectral domain optical coherence tomography (FRC SD-OCT) method. Other than FRC SD-OCT systems reported in literature, which employed devices such as electro-/acousto optic modulators or piezo-driven mirrors providing the phase modulations necessary for retrieval of the complex-valued signal, the system presented works without any additional phase shifting device. The required phase shift is introduced by the galvanometer scanner used for transversally scanning the sample beam. By means of a slight displacement of the probe beam with respect to the scanning mirror's pivot axis, the sample arm length and thus the phase is continuously modulated as the beam is scanned in lateral direction. From such modulated spectral data, the complex-valued data yielding a twofold increase of accessible depth range can be calculated using an algorithm based on the Hilbert transform. To demonstrate the performance of our method quantitative measurements of the suppression of mirror images as a function of induced phase shift were performed. In order to validate the FRC SD-OCT technique for high-speed imaging of biological tissue, we present full-range images of the human anterior chamber in vivo. PMID:19550607

  10. Reverse-phase HPLC of benzylpropionitrile dithiocarbamate complexes for the determination of priority pollutant metals

    SciTech Connect

    Park, Y.J.

    1990-01-01

    A new dithiocarbamate, benzylpropionitrile dithiocarbamate (BPDTC), has been synthesized for use in metal analysis. The HPLC behavior of metal chelates of BPDTC has been investigated for the simultaneous determination of antimony, cadmium, chromium, copper, mercury, nickel, lead, selenium, thallium, and zinc, all of which are on the Environmental Protection Agency's list of priority pollutant metals. Metals are extracted into dichloromethane as BPDTC chelates, and then separated on a C-18 column. Cobalt is added as an internal standard. The effects of pH and of three organic modifiers (methanol, acetonitrile, tetrahydrofuran) of the mobile phase on retention time have been investigated. Addition of dichloromethane to the mobile phase increases solubility and chelate stability, and improves the separation of metal BPDTC complexes. BPDTC is added to the aqueous mobile phase to reduce on-column dissociation of the complexes. Detection limits at 260 nm are in the range of 0.1 to 3 ppb using a 1 liter sample.

  11. Low-noise multiple watermarks technology based on complex double random phase encoding method

    NASA Astrophysics Data System (ADS)

    Zheng, Jihong; Lu, Rongwen; Sun, Liujie; Zhuang, Songlin

    2010-11-01

    Based on double random phase encoding method (DRPE), watermarking technology may provide a stable and robust method to protect the copyright of the printing. However, due to its linear character, DRPE exist the serious safety risk when it is attacked. In this paper, a complex coding method, which means adding the chaotic encryption based on logistic mapping before the DRPE coding, is provided and simulated. The results testify the complex method will provide better security protection for the watermarking. Furthermore, a low-noise multiple watermarking is studied, which means embedding multiple watermarks into one host printing and decrypt them with corresponding phase keys individually. The Digital simulation and mathematic analysis show that with the same total embedding weight factor, multiply watermarking will improve signal noise ratio (SNR) of the output printing image significantly. The complex multiply watermark method may provide a robust, stability, reliability copyright protection with higher quality printing image.

  12. Three-phase hollow fiber liquid-phase microextraction of organophosphorous nerve agent degradation products from complex samples.

    PubMed

    Desoubries, Charlotte; Chapuis-Hugon, Florence; Bossée, Anne; Pichon, Valérie

    2012-07-01

    Degradation products of chemical warfare agents are considered as important environmental and biological markers of chemical attacks. Alkyl methylphosphonic acids (AMPAs), resulting from the fast hydrolysis of nerve agents, such as sarin and soman, and the methylphosphonic acid (MPA), final degradation product of AMPAs, were determined from complex matrices by using an emergent and miniaturized extraction technique, the hollow fiber liquid-phase microextraction (HF-LPME), before their analysis by liquid chromatography coupled to mass spectrometry (LC-MS). After studying different conditions of separation in the reversed phase LC-MS analysis, the sample treatment method was set up. The three-phase HF-LPME was carried out by using a porous polypropylene (PP) hollow fiber impregnated with 1-octanol that separates the donor and acceptor aqueous media. Various extraction parameters were evaluated such as the volume of the sample, the effect of the pH and the salt addition to the sample, the pH of the acceptor phase, the extraction temperature, the stirring speed of the sample, the immersion time in the organic solvent and the time of extraction. The optimum conditions were applied to the determination of MPA and five AMPAs in real samples, such as surface waters and urine. Compounds were extracted from a 3 mL acidified sample into only 6 μL of alkaline water without any other pretreatment of the complex matrices. Enrichment factors (EFs) higher than 170 were obtained for three less polar AMPAs. Limits of quantification (LOQs) in the 0.013-5.3 ng mL(-1) range were obtained after microextraction of AMPAs from river water and in the range of 0.056-4.8 ng mL(-1) from urine samples with RSD values between 1 and 9%. PMID:22705170

  13. Endosomal Sorting Complex Required for Transport (ESCRT) Complexes Induce Phase-separated Microdomains in Supported Lipid Bilayers*

    PubMed Central

    Boura, Evzen; Ivanov, Vassili; Carlson, Lars-Anders; Mizuuchi, Kiyoshi; Hurley, James H.

    2012-01-01

    The endosomal sorting complex required for transport (ESCRT) system traffics ubiquitinated cargo to lysosomes via an unusual membrane budding reaction that is directed away from the cytosol. Here, we show that human ESCRT-II self-assembles into clusters of 10–100 molecules on supported lipid bilayers. The ESCRT-II clusters are functional in that they bind to ubiquitin and the ESCRT-III subunit VPS20 at nanomolar concentrations on membranes with the same stoichiometries observed in solution and in crystals. The clusters only form when cholesterol is included in the lipid mixture at >10 mol %. The clusters induce the formation of ordered membrane domains that exclude the dye 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindodicarbo-cyanine perchlorate. These results show that ESCRT complexes are capable of inducing lateral lipid phase separation under conditions where the lipids themselves do not spontaneously phase-separate. This property could facilitate ESCRT-mediated membrane budding. PMID:22718754

  14. High-speed spectral calibration by complex FIR filter in phase-sensitive optical coherence tomography

    PubMed Central

    Kim, Sangmin; Raphael, Patrick D.; Oghalai, John S.; Applegate, Brian E.

    2016-01-01

    Swept-laser sources offer a number of advantages for Phase-sensitive Optical Coherence Tomography (PhOCT). However, inter- and intra-sweep variability leads to calibration errors that adversely affect phase sensitivity. While there are several approaches to overcoming this problem, our preferred method is to simply calibrate every sweep of the laser. This approach offers high accuracy and phase stability at the expense of a substantial processing burden. In this approach, the Hilbert phase of the interferogram from a reference interferometer provides the instantaneous wavenumber of the laser, but is computationally expensive. Fortunately, the Hilbert transform may be approximated by a Finite Impulse-Response (FIR) filter. Here we explore the use of several FIR filter based Hilbert transforms for calibration, explicitly considering the impact of filter choice on phase sensitivity and OCT image quality. Our results indicate that the complex FIR filter approach is the most robust and accurate among those considered. It provides similar image quality and slightly better phase sensitivity than the traditional FFT-IFFT based Hilbert transform while consuming fewer resources in an FPGA implementation. We also explored utilizing the Hilbert magnitude of the reference interferogram to calculate an ideal window function for spectral amplitude calibration. The ideal window function is designed to carefully control sidelobes on the axial point spread function. We found that after a simple chromatic correction, calculating the window function using the complex FIR filter and the reference interferometer gave similar results to window functions calculated using a mirror sample and the FFT-IFFT Hilbert transform. Hence, the complex FIR filter can enable accurate and high-speed calibration of the magnitude and phase of spectral interferograms. PMID:27446666

  15. High-speed spectral calibration by complex FIR filter in phase-sensitive optical coherence tomography.

    PubMed

    Kim, Sangmin; Raphael, Patrick D; Oghalai, John S; Applegate, Brian E

    2016-04-01

    Swept-laser sources offer a number of advantages for Phase-sensitive Optical Coherence Tomography (PhOCT). However, inter- and intra-sweep variability leads to calibration errors that adversely affect phase sensitivity. While there are several approaches to overcoming this problem, our preferred method is to simply calibrate every sweep of the laser. This approach offers high accuracy and phase stability at the expense of a substantial processing burden. In this approach, the Hilbert phase of the interferogram from a reference interferometer provides the instantaneous wavenumber of the laser, but is computationally expensive. Fortunately, the Hilbert transform may be approximated by a Finite Impulse-Response (FIR) filter. Here we explore the use of several FIR filter based Hilbert transforms for calibration, explicitly considering the impact of filter choice on phase sensitivity and OCT image quality. Our results indicate that the complex FIR filter approach is the most robust and accurate among those considered. It provides similar image quality and slightly better phase sensitivity than the traditional FFT-IFFT based Hilbert transform while consuming fewer resources in an FPGA implementation. We also explored utilizing the Hilbert magnitude of the reference interferogram to calculate an ideal window function for spectral amplitude calibration. The ideal window function is designed to carefully control sidelobes on the axial point spread function. We found that after a simple chromatic correction, calculating the window function using the complex FIR filter and the reference interferometer gave similar results to window functions calculated using a mirror sample and the FFT-IFFT Hilbert transform. Hence, the complex FIR filter can enable accurate and high-speed calibration of the magnitude and phase of spectral interferograms. PMID:27446666

  16. Nonlinear light behaviors near phase transition in non-parity-time-symmetric complex waveguides.

    PubMed

    Nixon, Sean; Yang, Jianke

    2016-06-15

    Many classes of non-parity-time (PT)-symmetric waveguides with arbitrary gain and loss distributions still possess all-real linear spectrum or exhibit phase transition. In this Letter, nonlinear light behaviors in these complex waveguides are probed analytically near a phase transition. Using multi-scale perturbation methods, a nonlinear ordinary differential equation (ODE) is derived for the light's amplitude evolution. This ODE predicts that a single class of these non-PT-symmetric waveguides supports soliton families and amplitude-oscillating solutions both above and below linear phase transition, in close analogy with PT-symmetric systems. For the other classes of waveguides, the light's intensity always amplifies under the effect of nonlinearity, even if the waveguide is below the linear phase transition. These analytical predictions are confirmed by direct computations of the full system. PMID:27304279

  17. Nonlinear light behaviors near phase transition in non-parity-time-symmetric complex waveguides

    NASA Astrophysics Data System (ADS)

    Nixon, Sean; Yang, Jianke

    2016-06-01

    Many classes of non-parity-time (PT) symmetric waveguides with arbitrary gain and loss distributions still possess all-real linear spectrum or exhibit phase transition. In this article, nonlinear light behaviors in these complex waveguides are probed analytically near a phase transition. Using multi-scale perturbation methods, a nonlinear ordinary differential equation (ODE) is derived for the light's amplitude evolution. This ODE predicts that the first class of these non-PT-symmetric waveguides support continuous families of solitons and robust amplitude-oscillating solutions both above and below phase transition, in close analogy with PT-symmetric systems. For the other classes of waveguides, the light's intensity always amplifies under the effect of nonlinearity even if the waveguide is below phase transition. These analytical predictions are confirmed by direct computations of the full system.

  18. Temperature-dependent phase transitions of a complex biological membrane in zeptoliter volumes

    SciTech Connect

    Nikiforov, Maxim; Hohlbauch, Sophia; King, William P; Voitchovsky, K; Contera, S Antoranz; Jesse, Stephen; Kalinin, Sergei V; Proksch, Roger

    2011-01-01

    Phase transitions in purple membrane have been a topic of debate for the past two decades. In this work we present studies of a reversible transition of purple membrane in the 50 60 C range in zeptoliter volumes under different heating regimes (global heating and local heating). The temperature of the reversible phase transition is 52 5 C for both local and global heating, supporting the hypothesis that this transition is mainly due to a structural rearrangement of bR molecules and trimers. To achieve high resolution measurements of temperature-dependent phase transitions, a new scanning probe microscopy-based method was developed. We believe that our new technique can be extended to other biological systems and can contribute to the understanding of inhomogeneous phase transitions in complex systems.

  19. High pressure-low temperature phase diagram of barium: Simplicity versus complexity

    NASA Astrophysics Data System (ADS)

    Desgreniers, Serge; Tse, John S.; Matsuoka, Takahiro; Ohishi, Yasuo; Li, Quan; Ma, Yanming

    2015-11-01

    Barium holds a distinctive position among all elements studied upon densification. Indeed, it was the first example shown to violate the long-standing notion that high compression of simple metals should preserve or yield close-packed structures. From modest pressure conditions at room temperature, barium transforms at higher pressures from its simple structures to the extraordinarily complex atomic arrangements of the incommensurate and self-hosting Ba-IV phases. By a detailed mapping of the pressure/temperature structures of barium, we demonstrate the existence of another crystalline arrangement of barium, Ba-VI, at low temperature and high pressure. The simple structure of Ba-VI is unlike that of complex Ba-IV, the phase encountered in a similar pressure range at room temperature. First-principles calculations predict Ba-VI to be stable at high pressure and superconductive. The results illustrate the complexity of the low temperature-high pressure phase diagram of barium and the significant effect of temperature on structural phase transformations.

  20. High pressure–low temperature phase diagram of barium: Simplicity versus complexity

    SciTech Connect

    Desgreniers, Serge; Tse, John S.; Matsuoka, Takahiro; Ohishi, Yasuo

    2015-11-30

    Barium holds a distinctive position among all elements studied upon densification. Indeed, it was the first example shown to violate the long-standing notion that high compression of simple metals should preserve or yield close-packed structures. From modest pressure conditions at room temperature, barium transforms at higher pressures from its simple structures to the extraordinarily complex atomic arrangements of the incommensurate and self-hosting Ba-IV phases. By a detailed mapping of the pressure/temperature structures of barium, we demonstrate the existence of another crystalline arrangement of barium, Ba-VI, at low temperature and high pressure. The simple structure of Ba-VI is unlike that of complex Ba-IV, the phase encountered in a similar pressure range at room temperature. First-principles calculations predict Ba-VI to be stable at high pressure and superconductive. The results illustrate the complexity of the low temperature-high pressure phase diagram of barium and the significant effect of temperature on structural phase transformations.

  1. Gas-Phase Photoluminescence Characterization of Stoichiometrically Pure Nonanuclear Lanthanoid Hydroxo Complexes Comprising Europium or Gadolinium.

    PubMed

    Greisch, Jean-François; Chmela, Jiří; Harding, Michael E; Klopper, Wim; Kappes, Manfred M; Schooss, Detlef

    2016-04-01

    Gas-phase photoluminescence measurements involving mass-spectrometric techniques enable determination of the properties of selected molecular systems with knowledge of their exact composition and unaffected by matrix effects such as solvent interactions or crystal packing. The resulting reduced complexity facilitates a comparison with theory. Herein, we provide a detailed report of the intrinsic luminescence properties of nonanuclear europium(III) and gadolinium(III) 9-hydroxyphenalen-1-one (HPLN) hydroxo complexes. Luminescence spectra of [Eu9(PLN)16(OH)10](+) ions reveal an europium-centered emission dominated by a 4-fold split Eu(III) hypersensitive transition, while photoluminescence lifetime measurements for both complexes support an efficient europium sensitization via a PLN-centered triplet-state manifold. The combination of gas-phase measurements with density functional theory computations and ligand-field theory is used to discuss the antiprismatic core structure of the complexes and to shed light on the energy-transfer mechanism. This methodology is also employed to fit a new set of parameters, which improves the accuracy of ligand-field computations of Eu(III) electronic transitions for gas-phase species. PMID:26974169

  2. Characterization of fish gelatin-gum arabic complex coacervates as influenced by phase separation temperature.

    PubMed

    Anvari, Mohammad; Pan, Cheol-Ho; Yoon, Won-Byong; Chung, Donghwa

    2015-08-01

    The rheological and structural characteristics of fish gelatin (FG)-gum arabic (GA) complex coacervate phase, separated from an aqueous mixture of 1% FG and 1% GA at pH 3.5, were investigated as influenced by phase separation temperature. Decreasing the phase separation temperature from 40 to 10 °C lead to: (1) the formation of a coacervate phase with a larger volume fraction and higher biopolymer concentrations, which is more viscous, more structural resistant at low shear rates, more shear-thinning at high shear rates, and more condensed in microstructure, (2) a solid-like elastic behavior of the phase separated at 10 °C at a high oscillatory frequency, (3) the increase in gelling and melting temperatures of the coacervate phase (3.7-3.9 °C and 6.2-6.9 °C, respectively), (4) the formation of a more rigid and thermo-stable coacervate gel. The coacervate phase is regarded as a homogeneously networked biopolymer matrix dispersed with water vacuoles and its gel as a weak physical gel reinforced by FG-GA attractive electrostatic interactions. PMID:26054661

  3. Mapping the Complex Phase Behaviors of Aqueous Mixtures of κ-Carrageenan and Type B Gelatin.

    PubMed

    Cao, Yiping; Wang, Lu; Zhang, Ke; Fang, Yapeng; Nishinari, Katsuyoshi; Phillips, Glyn O

    2015-07-30

    We report a detailed and complete phase diagram for an aqueous mixture of oppositely charged gelling biopolymers, type B gelatin and κ-carrageenan (KC) at pH 7.0. The phase diagram is studied in the ionic strength-temperature coordinate by means of turbidity, rheological and differential scanning calorimetric measurements, and macroscopic phase compositional analysis. Seven phase regions are identified, including (I) compatible region, (II) electrostatically induced associative phase separation (EIAPS) region, (III) hydrogen bonding induced associative phase separation (HBIAPS) region, (IV) coexistence of EIAPS and HBIAPS, (V) segregative phase separation (SPS) region, (VI) coexistence of HBIAPS and SPS, and (VII) SPS trapped by gelation. The HBIAPS reported for the first time here is attributed to the extensive hydrogen bonding formation between gelatin and KC above their conformational transition temperatures, as probed by addition of urea and methylene blue as well as by 2D (1)H-(1)H NOESY NMR. NaCl is found to have dual effects on HBIAPS. The electrostatic complexation at lower ionic strength facilitates the formation of hydrogen bonds between gelatin and KC and hence the HBIAPS. It is believed that the local structural arrangement of gelatin molecules or the change in local solvent environment prior to triple helix formation during cooling enables the formation of hydrogen bonds with KC. PMID:26147592

  4. Temperature evolution of nickel sulphide phases from thiourea complex and their exchange bias effect

    NASA Astrophysics Data System (ADS)

    Kumar, Nitesh; Raman, N.; Sundaresan, A.

    2013-12-01

    Considering the very complex phase diagram of nickel sulphide, it is quite challenging to stabilize pure phases from a single precursor. Here, we obtain nanoparticles of various phases of nickel sulphide by decomposing nickel-thiourea complex at different temperatures. The first phase in the evolution is the one with the maximum sulphur content, namely, NiS2 nanoparticles obtained at 400 °C. As the temperature is increased, nanoparticles of phases with lesser sulphur content, NiS (600 °C) and Ni3S2 (800 °C) are formed. NiS2 nanoparticles exhibit weak ferromagnetic transition at 30 K and show a large exchange bias at 2 K. NiS nanoparticles are antiferromagnetic and show relatively smaller exchange bias effect. On the other hand, Ni3S2 nanoparticles exhibit very weak temperature dependent magnetization. Electrical measurements show that both NiS2 and NiS are semiconductors whereas Ni3S2 is a metal.

  5. Influence of Ionic Complexes on Phase Behavior of Polystyrene-b-poly(methyl methacrylate) Copolymers

    SciTech Connect

    Wang,J.; Chen, W.; Roy, C.; Sievert, J.; Russell, T.

    2008-01-01

    The influence of ionic complexes on phase behavior of PS-b-PMMA copolymers over a wide range of molecular weights and PS volume fractions was investigated by small-angle X-ray scattering (SAXS), grazing incidence small-angle X-ray scattering (GISAXS), transmission electron microscopy (TEM), and neutron reflectivity (NR). The disorder-to-order transition (DOT) in both symmetric and asymmetric copolymers indicates that the overall Flory-Huggins segmental interaction parameter, eff, between polystyrene (PS) and poly(methyl methacrylate) (PMMA) blocks with lithium-PMMA complexes is increased compared to that of the neat copolymers. This enhanced eff further results in an order-to-order transition (OOT), from spheres to cylinders, and an increase in the ordering and spacing of microdomains. Moreover, transitional metal ionic complexes, such as copper-PMMA complexes, are found to have the similar influence on phase behavior of PS-b-PMMA copolymers. The formation of ionic complexes in the copolymers not only offers a parameter to tune the degree of microphase separation of PS-b-PMMA copolymers but also provides a way to fabricate multifunctional materials.

  6. Incorporation of radionuclides into mineral phases via a thermally unstable complexant ligand

    SciTech Connect

    Apblett, A.W.; Georgieva, G.D.; Mague, J.T.

    1993-12-31

    The complexation and thermal behavior of pyruvic acid oxime (PAO) with representative cations associated with nuclear reprocessing waste has been investigated. This ligand has the dual advantage that it precipitates most of the cations from solution and these complexes decompose at ca. 150{degrees}C to CO{sub 2}, acetonitrile, and, initially, the metal hydroxide. Introduction of the appropriate elements required for Synroc phases to a simulated waste stream followed by NaPAO and disodium fumarate leads to precipitation of a metalorganic Synroc precursor in which the components have been intimately mixed at the molecular level. This approach circumvents incorporation of alkali metals in the final ceramic.

  7. Description and control of dissociation channels in gas-phase protein complexes

    NASA Astrophysics Data System (ADS)

    Thachuk, Mark; Fegan, Sarah K.; Raheem, Nigare

    2016-08-01

    Using molecular dynamics simulations of a coarse-grained model of the charged apo-hemoglobin protein complex, this work expands upon our initial report [S. K. Fegan and M. Thachuk, J. Am. Soc. Mass Spectrom. 25, 722-728 (2014)] about control of dissociation channels in the gas phase using specially designed charge tags. Employing a charge hopping algorithm and a range of temperatures, a variety of dissociation channels are found for activated gas-phase protein complexes. At low temperatures, a single monomer unfolds and becomes charge enriched. At higher temperatures, two additional channels open: (i) two monomers unfold and charge enrich and (ii) two monomers compete for unfolding with one eventually dominating and the other reattaching to the complex. At even higher temperatures, other more complex dissociation channels open with three or more monomers competing for unfolding. A model charge tag with five sites is specially designed to either attract or exclude charges. By attaching this tag to the N-terminus of specific monomers, the unfolding of those monomers can be decidedly enhanced or suppressed. In other words, using charge tags to direct the motion of charges in a protein complex provides a mechanism for controlling dissociation. This technique could be used in mass spectrometry experiments to direct forces at specific attachment points in a protein complex, and hence increase the diversity of product channels available for quantitative analysis. In turn, this could provide insight into the function of the protein complex in its native biological environment. From a dynamics perspective, this system provides an interesting example of cooperative behaviour involving motions with differing time scales.

  8. Activation of gas-phase uranyl: from an oxo to a nitrido complex.

    PubMed

    Gong, Yu; Vallet, Valérie; Michelini, Maria del Carmen; Rios, Daniel; Gibson, John K

    2014-01-01

    The uranyl moiety, UO2(2+), is ubiquitous in the chemistry of uranium, the most prevalent actinide. Replacing the strong uranium-oxygen bonds in uranyl with other ligands is very challenging, having met with only limited success. We report here uranyl oxo bond activation in the gas phase to form a terminal nitrido complex, a previously elusive transformation. Collision induced dissociation of gas-phase UO2(NCO)Cl2(-) in an ion trap produced the nitrido oxo complex, NUOCl2(-), and CO2. NUOCl2(-) was computed by DFT to have Cs symmetry and a singlet ground state. The computed bond length and order indicate a triple U-N bond. Endothermic activation of UO2(NCO)Cl2(-) to produce NUOCl2(-) and neutral CO2 was computed to be thermodynamically more favorable than NCO ligand loss. Complete reaction pathways for the CO2 elimination process were computed at the DFT level. PMID:24354492

  9. Violation of Lee-Yang circle theorem for Ising phase transitions on complex networks

    NASA Astrophysics Data System (ADS)

    Krasnytska, M.; Berche, B.; Holovatch, Yu.; Kenna, R.

    2015-09-01

    The Ising model on annealed complex networks with degree distribution decaying algebraically as p(K)∼ K-λ has a second-order phase transition at finite temperature if λ>3 . In the absence of space dimensionality, λ controls the transition strength; classical mean-field exponents apply for λ >5 but critical exponents are λ-dependent if λ < 5 . Here we show that, as for regular lattices, the celebrated Lee-Yang circle theorem is obeyed for the former case. However, unlike on regular lattices where it is independent of dimensionality, the circle theorem fails on complex networks when λ < 5 . We discuss the importance of this result for both theory and experiments on phase transitions and critical phenomena. We also investigate the finite-size scaling of Lee-Yang zeros in both regimes as well as the multiplicative logarithmic corrections which occur at λ=5 .

  10. Phase locking route behind complex periodic windows in a forced oscillator

    NASA Astrophysics Data System (ADS)

    Jan, Hengtai; Tsai, Kuo-Ting; Kuo, Li-wei

    2013-09-01

    Chaotic systems have complex reactions against an external driving force; even in cases with low-dimension oscillators, the routes to synchronization are diverse. We proposed a stroboscope-based method for analyzing driven chaotic systems in their phase space. According to two statistic quantities generated from time series, we could realize the system state and the driving behavior simultaneously. We demonstrated our method in a driven bi-stable system, which showed complex period windows under a proper driving force. With increasing periodic driving force, a route from interior periodic oscillation to phase synchronization through the chaos state could be found. Periodic windows could also be identified and the circumstances under which they occurred distinguished. Statistical results were supported by conditional Lyapunov exponent analysis to show the power in analyzing the unknown time series.

  11. Phase transitions via selective elemental vacancy engineering in complex oxide thin films

    NASA Astrophysics Data System (ADS)

    Lee, Sang A.; Jeong, Hoidong; Woo, Sungmin; Hwang, Jae-Yeol; Choi, Si-Young; Kim, Sung-Dae; Choi, Minseok; Roh, Seulki; Yu, Hosung; Hwang, Jungseek; Kim, Sung Wng; Choi, Woo Seok

    2016-04-01

    Defect engineering has brought about a unique level of control for Si-based semiconductors, leading to the optimization of various opto-electronic properties and devices. With regard to perovskite transition metal oxides, O vacancies have been a key ingredient in defect engineering, as they play a central role in determining the crystal field and consequent electronic structure, leading to important electronic and magnetic phase transitions. Therefore, experimental approaches toward understanding the role of defects in complex oxides have been largely limited to controlling O vacancies. In this study, we report on the selective formation of different types of elemental vacancies and their individual roles in determining the atomic and electronic structures of perovskite SrTiO3 (STO) homoepitaxial thin films fabricated by pulsed laser epitaxy. Structural and electronic transitions have been achieved via selective control of the Sr and O vacancy concentrations, respectively, indicating a decoupling between the two phase transitions. In particular, O vacancies were responsible for metal-insulator transitions, but did not influence the Sr vacancy induced cubic-to-tetragonal structural transition in epitaxial STO thin film. The independent control of multiple phase transitions in complex oxides by exploiting selective vacancy engineering opens up an unprecedented opportunity toward understanding and customizing complex oxide thin films.

  12. Phase transitions via selective elemental vacancy engineering in complex oxide thin films

    PubMed Central

    Lee, Sang A.; Jeong, Hoidong; Woo, Sungmin; Hwang, Jae-Yeol; Choi, Si-Young; Kim, Sung-Dae; Choi, Minseok; Roh, Seulki; Yu, Hosung; Hwang, Jungseek; Kim, Sung Wng; Choi, Woo Seok

    2016-01-01

    Defect engineering has brought about a unique level of control for Si-based semiconductors, leading to the optimization of various opto-electronic properties and devices. With regard to perovskite transition metal oxides, O vacancies have been a key ingredient in defect engineering, as they play a central role in determining the crystal field and consequent electronic structure, leading to important electronic and magnetic phase transitions. Therefore, experimental approaches toward understanding the role of defects in complex oxides have been largely limited to controlling O vacancies. In this study, we report on the selective formation of different types of elemental vacancies and their individual roles in determining the atomic and electronic structures of perovskite SrTiO3 (STO) homoepitaxial thin films fabricated by pulsed laser epitaxy. Structural and electronic transitions have been achieved via selective control of the Sr and O vacancy concentrations, respectively, indicating a decoupling between the two phase transitions. In particular, O vacancies were responsible for metal-insulator transitions, but did not influence the Sr vacancy induced cubic-to-tetragonal structural transition in epitaxial STO thin film. The independent control of multiple phase transitions in complex oxides by exploiting selective vacancy engineering opens up an unprecedented opportunity toward understanding and customizing complex oxide thin films. PMID:27033718

  13. Phase transitions via selective elemental vacancy engineering in complex oxide thin films.

    PubMed

    Lee, Sang A; Jeong, Hoidong; Woo, Sungmin; Hwang, Jae-Yeol; Choi, Si-Young; Kim, Sung-Dae; Choi, Minseok; Roh, Seulki; Yu, Hosung; Hwang, Jungseek; Kim, Sung Wng; Choi, Woo Seok

    2016-01-01

    Defect engineering has brought about a unique level of control for Si-based semiconductors, leading to the optimization of various opto-electronic properties and devices. With regard to perovskite transition metal oxides, O vacancies have been a key ingredient in defect engineering, as they play a central role in determining the crystal field and consequent electronic structure, leading to important electronic and magnetic phase transitions. Therefore, experimental approaches toward understanding the role of defects in complex oxides have been largely limited to controlling O vacancies. In this study, we report on the selective formation of different types of elemental vacancies and their individual roles in determining the atomic and electronic structures of perovskite SrTiO3 (STO) homoepitaxial thin films fabricated by pulsed laser epitaxy. Structural and electronic transitions have been achieved via selective control of the Sr and O vacancy concentrations, respectively, indicating a decoupling between the two phase transitions. In particular, O vacancies were responsible for metal-insulator transitions, but did not influence the Sr vacancy induced cubic-to-tetragonal structural transition in epitaxial STO thin film. The independent control of multiple phase transitions in complex oxides by exploiting selective vacancy engineering opens up an unprecedented opportunity toward understanding and customizing complex oxide thin films. PMID:27033718

  14. Organometallic complexes with biological molecules. XVIII. Alkyltin(IV) cephalexinate complexes: synthesis, solid state and solution phase investigations.

    PubMed

    Di Stefano, R; Scopelliti, M; Pellerito, C; Casella, G; Fiore, T; Stocco, G C; Vitturi, R; Colomba, M; Ronconi, L; Sciacca, I D; Pellerito, L

    2004-03-01

    Dialkyltin(IV) and trialkyltin(IV) complexes of the deacetoxycephalo-sporin-antibiotic cephalexin [7-(d-2-amino-2-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid] (Hceph) have been synthesized and investigated both in solid and solution phase. Analytical and thermogravimetric data supported the general formula Alk(2)SnOHceph(.)H(2)O and Alk(3)Snceph(.)H(2)O (Alk=Me, n-Bu), while structural information has been gained by FT-IR, (119)Sn Mössbauer and (1)H, (13)C, (119)Sn NMR data. In particular, IR results suggested polymeric structures both for Alk(2)SnOHceph(.)H(2)O and Alk(3)Snceph(.)H(2)O. Moreover, cephalexin appears to behave as monoanionic tridentate ligand coordinating the tin(IV) atom through ester-type carboxylate, as well as through beta-lactam carbonyl oxygen atoms and the amino nitrogen donor atoms in Alk(2)SnOHceph(.)H(2)O complexes. On the basis of (119)Sn Mössbauer spectroscopy it could be inferred that tin(IV) was hexacoordinated in such complexes in the solid state, showing skew trapezoidal configuration. As far as Alk(3)Sn(IV)ceph(.)H(2)O derivatives are concerned, cephalexin coordinated the Alk(3)Sn moiety through the carboxylate acting as a bridging bidentate monoanionic group. Again, (119)Sn Mössbauer spectroscopy led us to propose a trigonal configuration around the tin(IV) atom, with R(3)Sn equatorial disposition and bridging carboxylate oxygen atoms in the axial positions. The nature of the complexes in solution state was investigated by using (1)H, (13)C and (119)Sn NMR spectroscopy. Finally, the cytotoxic activity of organotin(IV) cephalexinate derivatives has been tested using two different chromosome-staining techniques Giemsa and CMA(3), towards spermatocyte chromosomes of the mussel Brachidontes pharaonis (Mollusca: Bivalvia). Colchicinized-like mitoses (c-mitoses) on slides obtained from animals exposed to organotin(IV) cephalexinate compounds, demonstrated the high mitotic spindle-inhibiting potentiality of these chemicals

  15. Influence of salt bridge interactions on the gas-phase stability of DNA/peptide complexes

    NASA Astrophysics Data System (ADS)

    Alves, Sandra; Woods, Amina; Delvolvé, Alice; Tabet, Jean Claude

    2008-12-01

    Negative ion mode electrospray ionization mass spectrometry was used to study DNA duplexes-peptide interaction. In the present study, we show that peptides that contain two adjacent basic residues interact noncovalently with DNA single strand or duplex. Fragmentation of the complexes between peptides containing basic residues and DNA were studied under collisions and showed unexpected dissociation pathways, as previously reported for peptide-peptide interactions. The binary complexes are dissociated either along fragmentation of the covalent bonds of the peptide backbone and/or along the single DNA strand backbone cleavage without disruption of noncovalent interaction, which demonstrates the strong binding of peptide to the DNA strand. Sequential MS/MS and MSn were further performed on ternary complexes formed between duplexes and peptides to investigate the nature of interaction. The CID spectra showed as major pathway the disruption of the noncovalent interactions and the formation of binary complexes and single-strand ions, directed by the nucleic acid gas-phase acidity. Indeed, a preferential formation of complexes with thymidine containing single strands is observed. An alternative pathway is also detected, in which complexes are dissociated along the covalent bond of the peptide and/or DNA according to the basicity. Our experimental data suggest the presence of strong salt bridge interactions between DNA and peptides containing basic residues.

  16. Phase effects in masking by harmonic complexes: detection of bands of speech-shaped noise.

    PubMed

    Deroche, Mickael L D; Culling, John F; Chatterjee, Monita

    2014-11-01

    When phase relationships between partials of a complex masker produce highly modulated temporal envelopes on the basilar membrane, listeners may detect speech information from temporal dips in the within-channel masker envelopes. This source of masking release (MR) is however located in regions of unresolved masker partials and it is unclear how much of the speech information in these regions is really needed for intelligibility. Also, other sources of MR such as glimpsing in between resolved masker partials may provide sufficient information from regions that disregard phase relationships. This study simplified the problem of speech recognition to a masked detection task. Target bands of speech-shaped noise were restricted to frequency regions containing either only resolved or only unresolved masker partials, as a function of masker phase relationships (sine or random), masker fundamental frequency (F0) (50, 100, or 200 Hz), and masker spectral profile (flat-spectrum or speech-shaped). Although masker phase effects could be observed in unresolved regions at F0s of 50 and 100 Hz, it was only at 50-Hz F0 that detection thresholds were ever lower in unresolved than in resolved regions, suggesting little role of envelope modulations for harmonic complexes with F0s in the human voice range and at moderate level. PMID:25373972

  17. Laser Spectroscopic Study of Cold Gas-Phase Host-Guest Complexes of Crown Ethers.

    PubMed

    Ebata, Takayuki; Inokuchi, Yoshiya

    2016-06-01

    The structure, molecular recognition, and inclusion effect on the photophysics of guest species are investigated for neutral and ionic cold host-guest complexes of crown ethers (CEs) in the gas phase. Here, the cold neutral host-guest complexes are produced by a supersonic expansion technique and the cold ionic complexes are generated by the combination of electrospray ionization (ESI) and a cryogenically cooled ion trap. The host species are 3n-crown-n (3nCn; n = 4, 5, 6, 8) and (di)benzo-3n-crown-n ((D)B3nCn; n = 4, 5, 6, 8). For neutral guests, we have chosen water and aromatic molecules, such as phenol and benzenediols, and as ionic species we have chosen alkali-metal ions (M(+) ). The electronic spectra and isomer-specific vibrational spectra for the complexes are observed with various laser spectroscopic methods: laser-induced fluorescence (LIF); ultraviolet-ultraviolet hole-burning (UV-UV HB); and IR-UV double resonance (IR-UV DR) spectroscopy. The obtained spectra are analyzed with the aid of quantum chemical calculations. We will discuss how the host and guest species change their flexible structures for forming best-fit stable complexes (induced fitting) and what kinds of interactions are operating for the stabilization of the complexes. For the alkali metal ion•CE complexes, we investigate the solvation effect by attaching water molecules. In addition to the ground-state stabilization problem, we will show that the complexation leads to a drastic effect on the excited-state electronic structure and dynamics of the guest species, which we call a "cage-like effect". PMID:27006080

  18. Cooperativity or phase transition? Unfolding transition of DNA cationic surfactant complex

    NASA Astrophysics Data System (ADS)

    Mel'nikov, Sergey M.; Sergeyev, Vladimir G.; Yoshikawa, Kenichi; Takahashi, Hiroshi; Hatta, Ichiro

    1997-11-01

    We recently reported that single duplex DNA, with the size above the order of several tens kilobase pairs, undergoes a large discrete transition from an elongated coil into a collapsed globule with the addition of a cationic surfactant. In the present article, we describe the manner of the unfolding transition of compact long DNA, or globule DNA, complexed with cationic surfactants, cetyltrimethylammonium bromide (CTAB) and distearyldimethylammonium bromide (D18DAB), as is induced by the addition of sodium bromide. The conformational dynamics of individual single duplex T4DNA molecules was directly observed with the use of fluorescence microscopy. We found that on the level of individual DNAs, the salt-induced unfolding transition of the globules is largely discrete, or first-order phase transition for the both complexes with CTAB and D18DAB. On the other hand, for the ensemble average of the DNAs, the transition is discrete with CTAB but is continuous (sigmoidal) with D18DAB. The discreteness for the coil-globule transition in the ensemble of DNAs complexed with CTAB is attributed to the existence of the phase transition in whole over the bulk solution: the sphere-rod transition in surfactant micelles. On the other hand, for D18DAB such phase transition on the micelle structure in the bulk solution seems to be absent. In correspondence to such a large difference on the manner of the transition, x-ray diffraction analysis indicates marked difference on the structure of DNA complexes with CTAB and with D18DAB.

  19. Phase behavior of electrostatically complexed polyelectrolyte gels using an embedded fluctuation model.

    PubMed

    Audus, Debra J; Gopez, Jeffrey D; Krogstad, Daniel V; Lynd, Nathaniel A; Kramer, Edward J; Hawker, Craig J; Fredrickson, Glenn H

    2015-02-14

    Nanostructured, responsive hydrogels formed due to electrostatic interactions have promise for applications such as drug delivery and tissue mimics. These physically cross-linked hydrogels are composed of an aqueous solution of oppositely charged triblocks with charged end-blocks and neutral, hydrophilic mid-blocks. Due to their electrostatic interactions, the end-blocks microphase separate and form physical cross-links that are bridged by the mid-blocks. The structure of this system was determined using a new, efficient embedded fluctuation (EF) model in conjunction with self-consistent field theory. The calculations using the EF model were validated against unapproximated field-theoretic simulations with complex Langevin sampling and were found consistent with small angle X-ray scattering (SAXS) measurements on an experimental system. Using both the EF model and SAXS, phase diagrams were generated as a function of end-block fraction and polymer concentration. Several structures were observed including a body-centered cubic sphere phase, a hexagonally packed cylinder phase, and a lamellar phase. Finally, the EF model was used to explore how parameters that directly relate to polymer chemistry can be tuned to modify the resulting phase diagram, which is of practical interest for the development of new hydrogels. PMID:25567551

  20. Formation of complex organic molecules in cold objects: the role of gas-phase reactions

    NASA Astrophysics Data System (ADS)

    Balucani, Nadia; Ceccarelli, Cecilia; Taquet, Vianney

    2015-04-01

    While astrochemical models are successful in reproducing many of the observed interstellar species, they have been struggling to explain the observed abundances of complex organic molecules. Current models tend to privilege grain surface over gas-phase chemistry in their formation. One key assumption of those models is that radicals trapped in the grain mantles gain mobility and react on lukewarm ( ≳ 30 K) dust grains. Thus, the recent detections of methyl formate (MF) and dimethyl ether (DME) in cold objects represent a challenge and may clarify the respective role of grain-surface and gas-phase chemistry. We propose here a new model to form DME and MF with gas-phase reactions in cold environments, where DME is the precursor of MF via an efficient reaction overlooked by previous models. Furthermore, methoxy, a precursor of DME, is also synthesized in the gas phase from methanol, which is desorbed by a non-thermal process from the ices. Our new model reproduces fairly well the observations towards L1544. It also explains, in a natural way, the observed correlation between DME and MF. We conclude that gas-phase reactions are major actors in the formation of MF, DME and methoxy in cold gas. This challenges the exclusive role of grain-surface chemistry and favours a combined grain-gas chemistry.

  1. Design of phase-only, binary phase-only, and complex ternary matched filters with increased signal-to-noise ratios for colored noise

    NASA Technical Reports Server (NTRS)

    Kumar, B. V. K. V.; Juday, Richard D.

    1991-01-01

    An algorithm is provided for treating nonwhite additive noise in determining regions of support for phase-only filters, binary phase-only filters, and complex ternary matched filters. It is analytically shown to be optimal in the signal-to-noise ratio sense. It extends earlier research that assumed white noise.

  2. Significance of chamber pressure to complex multi-phase physics in jet engine fuel injection processes

    NASA Astrophysics Data System (ADS)

    Dahms, Rainer; Oefelein, Joseph

    2014-11-01

    Injection processes in jet engines at chamber pressures in excess of the thermodynamic critical pressure of the liquid fuel are not well understood. Under some conditions, a distinct two-phase interface may not exist anymore which eliminates the presence of classical spray atomization phenomena. A comprehensive model for jet engine fuel injections is derived to quantify the conditions under which the interfacial dynamics transition to diffusion-dominated mixing processes without surface tension. At certain conditions, the model shows two-phase interfaces with substantially increased thicknesses and distinctively reduced mean free paths in comparison to ambient pressure conditions. Then, the underlying assumptions of a distinct two-phase interface do not apply anymore and the interface along with its surface tension is shown to deteriorate as it broadens substantially. As a consequence of this physical complexity, the conceptual view of spray atomization and evaporation as an appropriate model for jet engine injection processes is, contrary to conventional wisdom, questionable at certain operating conditions. Instead, a Large Eddy Simulation using a dense-fluid approximation is applied which takes the complex thermo-physics of real-fluid behavior into account.

  3. Phase Transition in Postsynaptic Densities Underlies Formation of Synaptic Complexes and Synaptic Plasticity.

    PubMed

    Zeng, Menglong; Shang, Yuan; Araki, Yoichi; Guo, Tingfeng; Huganir, Richard L; Zhang, Mingjie

    2016-08-25

    Postsynaptic densities (PSDs) are membrane semi-enclosed, submicron protein-enriched cellular compartments beneath postsynaptic membranes, which constantly exchange their components with bulk aqueous cytoplasm in synaptic spines. Formation and activity-dependent modulation of PSDs is considered as one of the most basic molecular events governing synaptic plasticity in the nervous system. In this study, we discover that SynGAP, one of the most abundant PSD proteins and a Ras/Rap GTPase activator, forms a homo-trimer and binds to multiple copies of PSD-95. Binding of SynGAP to PSD-95 induces phase separation of the complex, forming highly concentrated liquid-like droplets reminiscent of the PSD. The multivalent nature of the SynGAP/PSD-95 complex is critical for the phase separation to occur and for proper activity-dependent SynGAP dispersions from the PSD. In addition to revealing a dynamic anchoring mechanism of SynGAP at the PSD, our results also suggest a model for phase-transition-mediated formation of PSD. PMID:27565345

  4. Prestack depth migration for complex 2D structure using phase-screen propagators

    SciTech Connect

    Roberts, P.; Huang, Lian-Jie; Burch, C.; Fehler, M.; Hildebrand, S.

    1997-11-01

    We present results for the phase-screen propagator method applied to prestack depth migration of the Marmousi synthetic data set. The data were migrated as individual common-shot records and the resulting partial images were superposed to obtain the final complete Image. Tests were performed to determine the minimum number of frequency components required to achieve the best quality image and this in turn provided estimates of the minimum computing time. Running on a single processor SUN SPARC Ultra I, high quality images were obtained in as little as 8.7 CPU hours and adequate images were obtained in as little as 4.4 CPU hours. Different methods were tested for choosing the reference velocity used for the background phase-shift operation and for defining the slowness perturbation screens. Although the depths of some of the steeply dipping, high-contrast features were shifted slightly the overall image quality was fairly insensitive to the choice of the reference velocity. Our jests show the phase-screen method to be a reliable and fast algorithm for imaging complex geologic structures, at least for complex 2D synthetic data where the velocity model is known.

  5. Novel complex MAD phasing and RNase H structural insights using selenium oligonucleotides

    SciTech Connect

    Abdur, Rob; Gerlits, Oksana O.; Gan, Jianhua; Jiang, Jiansheng; Salon, Jozef; Kovalevsky, Andrey Y.; Chumanevich, Alexander A.; Weber, Irene T.; Huang, Zhen

    2014-02-01

    Selenium-derivatized oligonucleotides may facilitate phase determination and high-resolution structure determination for protein–nucleic acid crystallography. The Se atom-specific mutagenesis (SAM) strategy may also enhance the study of nuclease catalysis. The crystal structures of protein–nucleic acid complexes are commonly determined using selenium-derivatized proteins via MAD or SAD phasing. Here, the first protein–nucleic acid complex structure determined using selenium-derivatized nucleic acids is reported. The RNase H–RNA/DNA complex is used as an example to demonstrate the proof of principle. The high-resolution crystal structure indicates that this selenium replacement results in a local subtle unwinding of the RNA/DNA substrate duplex, thereby shifting the RNA scissile phosphate closer to the transition state of the enzyme-catalyzed reaction. It was also observed that the scissile phosphate forms a hydrogen bond to the water nucleophile and helps to position the water molecule in the structure. Consistently, it was discovered that the substitution of a single O atom by a Se atom in a guide DNA sequence can largely accelerate RNase H catalysis. These structural and catalytic studies shed new light on the guide-dependent RNA cleavage.

  6. The steady-state phase distribution of the motor switch complex model of Halobacterium salinarum.

    PubMed

    del Rosario, Ricardo C H; Diener, Francine; Diener, Marc; Oesterhelt, Dieter

    2009-12-01

    Steady-state analysis is performed on the kinetic model for the switch complex of the flagellar motor of Halobacterium salinarum (Nutsch et al.). The existence and uniqueness of a positive steady-state of the system is established and it is demonstrated why the steady-state is centered around the competent phase, a state of the motor in which it is able to respond to light stimuli. It is also demonstrated why the steady-state shifts to the refractory phase when the steady-state value of the response regulator CheYP increases. This work is one aspect of modeling in systems biology wherein the mathematical properties of a model are established. PMID:19857501

  7. Exact calculations of phase and membrane equilibria for complex fluids by Monte Carlo simulation

    SciTech Connect

    Panagiotopoulos, A.Z.

    1990-08-28

    The general objective of this project is the investigation of phase equilibria for complex fluids using a novel methodology, Monte Carlo simulation in the Gibbs ensemble. The methodology enables the direct determination of the properties of two coexisting fluid phases (e.g. a liquid at equilibrium with its vapor) from a single computer experiment, and is applicable to multicomponent systems with arbitrary equilibrium constraints imposed. The specific goals of this work are to adapt the Gibbs technique to (a) highly asymmetric mixtures with large differences in size and potential energies of interaction (b) chain molecules and (c) ionic systems. Significant progress has been made in all three areas. In this paper, we will briefly describe the progress made in each area, using the same numbering scheme for the tasks as in the original proposal.

  8. Wound-up phase turbulence in the complex Ginzburg-Landau equation

    NASA Astrophysics Data System (ADS)

    Montagne, R.; Hernández-García, E.; Amengual, A.; San Miguel, M.

    1997-07-01

    We consider phase turbulent regimes with nonzero winding number in the one-dimensional complex Ginzburg-Landau equation. We find that phase turbulent states with winding number larger than a critical one are only transients and decay to states within a range of allowed winding numbers. The analogy with the Eckhaus instability for nonturbulent waves is stressed. The transition from phase to defect turbulence is interpreted as an ergodicity breaking transition that occurs when the range of allowed winding numbers vanishes. We explain the states reached at long times in terms of three basic states, namely, quasiperiodic states, frozen turbulence states, and riding turbulence states. Justification and some insight into them are obtained from an analysis of a phase equation for nonzero winding number: Rigidly moving solutions of this equation, which correspond to quasiperiodic and frozen turbulence states, are understood in terms of periodic and chaotic solutions of an associated system of ordinary differential equations. A short report of some of our results has already been published [R. Montagne et al., Phys. Rev. Lett. 77, 267 (1996)].

  9. Deciphering the internal complexity of living cells with quantitative phase microscopy: a multiscale approach

    NASA Astrophysics Data System (ADS)

    Martinez-Torres, Cristina; Laperrousaz, Bastien; Berguiga, Lotfi; Boyer-Provera, Elise; Elezgaray, Juan; Nicolini, Franck E.; Maguer-Satta, Veronique; Arneodo, Alain; Argoul, Françoise

    2015-09-01

    The distribution of refractive indices (RIs) of a living cell contributes in a nonintuitive manner to its optical phase image and quite rarely can be inverted to recover its internal structure. The interpretation of the quantitative phase images of living cells remains a difficult task because (1) we still have very little knowledge on the impact of its internal macromolecular complexes on the local RI and (2) phase changes produced by light propagation through the sample are mixed with diffraction effects by the internal cell bodies. We propose to implement a two-dimensional wavelet-based contour chain detection method to distinguish internal boundaries based on their greatest optical path difference gradients. These contour chains correspond to the highest image phase contrast and follow the local RI inhomogeneities linked to the intracellular structural intricacy. Their statistics and spatial distribution are the morphological indicators suited for comparing cells of different origins and/or to follow their transformation in pathologic situations. We use this method to compare nonadherent blood cells from primary and laboratory culture origins and to assess the internal transformation of hematopoietic stem cells by the transduction of the BCR-ABL oncogene responsible for the chronic myelogenous leukemia.

  10. Colloidal TiO2 nanocrystals prepared from peroxotitanium complex solutions: phase evolution from different precursors.

    PubMed

    Seok, Sang Il; Vithal, Muga; Chang, Jeong Ah

    2010-06-01

    We report the preparation of nanocrystalline anatase and rutile TiO(2) from aqueous peroxotitanium complex (PTC) solutions and their characterization by powder X-ray diffraction (XRD), infrared spectroscopy, and Raman spectroscopy. The phase evolution of TiO(2) prepared using PTC derived from different precursors, i.e., TiCl(4) and titanium tetraisopropoxide (TTIP), is related to the nature of the intermediate steps. Phase-pure nanoanatase was formed in PTC solution derived from TiCl(4), while a mixture of minor anatase and dominant rutile were prepared from PTC when TTIP was used as precursor. On the other hand, in the case of calcining PTC powders in air, a pure anatase phase of TiO(2) was obtained, regardless of the precursor used. Thus, the formation and attachment of hydrated TiO(6) units or TiO(2)·xH(2)O under a different environment, especially pH, plays a critical role in determining the phase during the crystallization of TiO(2). PMID:20227087

  11. Detecting critical state before phase transition of complex systems by hidden Markov model

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Chen, Pei; Li, Yongjun; Chen, Luonan

    Identifying the critical state or pre-transition state just before the occurrence of a phase transition is a challenging task, because the state of the system may show little apparent change before this critical transition during the gradual parameter variations. Such dynamics of phase transition is generally composed of three stages, i.e., before-transition state, pre-transition state, and after-transition state, which can be considered as three different Markov processes. Thus, based on this dynamical feature, we present a novel computational method, i.e., hidden Markov model (HMM), to detect the switching point of the two Markov processes from the before-transition state (a stationary Markov process) to the pre-transition state (a time-varying Markov process), thereby identifying the pre-transition state or early-warning signals of the phase transition. To validate the effectiveness, we apply this method to detect the signals of the imminent phase transitions of complex systems based on the simulated datasets, and further identify the pre-transition states as well as their critical modules for three real datasets, i.e., the acute lung injury triggered by phosgene inhalation, MCF-7 human breast cancer caused by heregulin, and HCV-induced dysplasia and hepatocellular carcinoma.

  12. Evolution of pattern complexity in the Cahn-Hilliard theory of phase separation

    SciTech Connect

    Gameiro, Marcio; Mischaikow, Konstantin; Wanner, Thomas . E-mail: wanner@math.gmu.edu

    2005-02-01

    Phase separation processes in compound materials can produce intriguing and complicated patterns. Yet, characterizing the geometry of these patterns quantitatively can be quite challenging. In this paper we propose the use of computational algebraic topology to obtain such a characterization. Our method is illustrated for the complex microstructures observed during spinodal decomposition and early coarsening in both the deterministic Cahn-Hilliard theory, as well as in the stochastic Cahn-Hilliard-Cook model. While both models produce microstructures that are qualitatively similar to the ones observed experimentally, our topological characterization points to significant differences. One particular aspect of our method is its ability to quantify boundary effects in finite size systems.

  13. Chemical Frustration. A Design Principle for the Discovery of New Complex Alloy and Intermetallic Phases, Final Report

    SciTech Connect

    Fredrickson, Daniel C

    2015-06-23

    Final technical report for "Chemical Frustration: A Design Principle for the Discovery of New Complex Alloy and Intermetallic Phases" funded by the Office of Science through the Materials Chemistry Program of the Office of Basic Energy Sciences.

  14. Crystallization of and selenomethionine phasing strategy for a SETMAR-DNA complex.

    PubMed

    Chen, Qiujia; Georgiadis, Millie

    2016-09-01

    Transposable elements have played a critical role in the creation of new genes in all higher eukaryotes, including humans. Although the chimeric fusion protein SETMAR is no longer active as a transposase, it contains both the DNA-binding domain (DBD) and catalytic domain of the Hsmar1 transposase. The amino-acid sequence of the DBD has been virtually unchanged in 50 million years and, as a consequence, SETMAR retains its sequence-specific binding to the ancestral Hsmar1 terminal inverted repeat (TIR) sequence. Thus, the DNA-binding activity of SETMAR is likely to have an important biological function. To determine the structural basis for the recognition of TIR DNA by SETMAR, the design of TIR-containing oligonucleotides and SETMAR DBD variants, crystallization of DBD-DNA complexes, phasing strategies and initial phasing experiments are reported here. An unexpected finding was that oligonucleotides containing two BrdUs in place of thymidines produced better quality crystals in complex with SETMAR than their natural counterparts. PMID:27599863

  15. Evolution of phase and morphology of titanium dioxide induced from peroxo titanate complex aqueous solution.

    PubMed

    Chang, Jeong Ah; Vithal, Muga; Baek, In Chan; Seok, Sang Il

    2010-01-01

    We demonstrate the growth of anatase TiO2 in nanospheres and rutile TiO2 in nanorods, by the hydrolysis of titanium tetraisopropoxide (TTIP) in the presence of hydrogen peroxide at 100 degrees C using sol-gel method. X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and surface area measurement techniques are used to characterize the phase and shape developments of TiO2 obtained from peroxo titanate complex in an aqueous solution at 100 degrees C. Peroxo titanate complexes were prepared by a reaction of titanium hydroxide, formed by hydrolysis of titanium tetraisopropoxide (TTIP), and different amounts of hydrogen peroxide (H2O2). TEM and XRD investigations reveal that the size of spheres (anatase) and rods (rutile) are about 8 nm (diameter) and about 13 x 29 nm approximately 20 x 75 nm (width x length) respectively. The influence of molar ratio of H2O2/TTIP on the phase and morphology of TiO2 is presented. A mixture of anatase spheres and short rutile rods are formed at low H2O2/TTIP ratio while predominantly rutile a quit long rods are formed at higher H2O2/TTIP ratio. PMID:20352827

  16. Deciphering complex, functional structures with synchrotron-based absorption and phase contrast tomographic microscopy

    NASA Astrophysics Data System (ADS)

    Stampanoni, M.; Reichold, J.; Weber, B.; Haberthür, D.; Schittny, J.; Eller, J.; Büchi, F. N.; Marone, F.

    2010-09-01

    Nowadays, thanks to the high brilliance available at modern, third generation synchrotron facilities and recent developments in detector technology, it is possible to record volumetric information at the micrometer scale within few minutes. High signal-to-noise ratio, quantitative information on very complex structures like the brain micro vessel architecture, lung airways or fuel cells can be obtained thanks to the combination of dedicated sample preparation protocols, in-situ acquisition schemes and cutting-edge imaging analysis instruments. In this work we report on recent experiments carried out at the TOMCAT beamline of the Swiss Light Source [1] where synchrotron-based tomographic microscopy has been successfully used to obtain fundamental information on preliminary models for cerebral fluid flow [2], to provide an accurate mesh for 3D finite-element simulation of the alveolar structure of the pulmonary acinus [3] and to investigate the complex functional mechanism of fuel cells [4]. Further, we introduce preliminary results on the combination of absorption and phase contrast microscopy for the visualization of high-Z nanoparticles in soft tissues, a fundamental information when designing modern drug delivery systems [5]. As an outlook we briefly discuss the new possibilities offered by high sensitivity, high resolution grating interferomtery as well as Zernike Phase contrast nanotomography [6].

  17. Vibrational Spectroscopy of Mass Selected [UO2(ligand)n]2+ Complexes in the Gas Phase

    SciTech Connect

    Gary S. Groenewold; Anita Gianotto; Michael Vanstipdonk; Kevin C. Cossel; David T. Moore,; Nick Polfer; Jos Oomens

    2006-03-01

    The gas-phase infrared spectra of discrete uranyl ([UO2]2+) complexes ligated with acetone and/or acetonitrile were used to evaluate systematic trends of ligation on the position of the O=U=O stretch, and to enable rigorous comparison with the results of computational studies. Ionic uranyl complexes isolated in a Fourier transform ion cyclotron resonance mass spectrometer were fragmented via infrared multiphoton dissociation using a free electron laser scanned over the mid-IR wavelengths. The asymmetric O=U=O stretching frequency was measured at 1017 cm-1 for [UO2(CH3COCH3)2]2+, and was systematically red shifted to 1000 and 988 cm-1 by the addition of a third and fourth acetone ligands, respectively, which was consistent with more donation of electron density to the uranium center in complexes with higher coordination number. The experimental measurements were in good agreement with values generated computationally using LDA, B3LYP, and ZORA-PW91 approaches. In contrast to the uranyl frequency shifts, the carbonyl frequencies of the acetone ligands were progressively blue shifted as the number of ligands increased from 2 to 4, and approached that of free acetone. This observation was consistent with the formation of weaker noncovalent bonds between uranium and the carbonyl oxygen as the extent of ligation increases. Similar trends were observed for [UO2(CH3CN)n]2+ complexes although the magnitude of the red shift in the uranyl frequency upon addition more acetonitrile ligands was smaller than for acetone, consistent with the more modest nucleophilic nature of acetonitrile. This conclusion was amplified by the uranyl stretching frequencies measured for mixed acetone/acetonitrile complexes, which showed that substitution of one acetone for one acetonitrile produced a modest red shift of 3 to 6 cm-1.

  18. Determination of complex formation constants by phase sensitive alternating current polarography: Cadmium-polymethacrylic acid and cadmium-polygalacturonic acid.

    PubMed

    Garrigosa, Anna Maria; Gusmão, Rui; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

    2007-10-15

    The use of phase sensitive alternating current polarography (ACP) for the evaluation of complex formation constants of systems where electrodic adsorption is present has been proposed. The applicability of the technique implies the previous selection of the phase angle where contribution of capacitive current is minimized. This is made using Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) in the analysis of ACP measurements at different phase angles. The method is checked by the study of the complexation of Cd by polymethacrylic (PMA) and polygalacturonic (PGA) acids, and the optimal phase angles have been ca. -10 degrees for Cd-PMA and ca. -15 degrees for Cd-PGA systems. The goodness of phase sensitive ACP has been demonstrated comparing the determined complex formation constants with those obtained by reverse pulse polarography, a technique that minimizes the electrode adsorption effects on the measured currents. PMID:19073101

  19. Complexity measure and quantum shape-phase transitions in the two-dimensional limit of the vibron model.

    PubMed

    Romera, Elvira; Calixto, Manuel; Nagy, Ágnes

    2014-07-01

    We obtain a characterization of quantum shape-phase transitions in the terms of complexity measures in the two-dimensional limit of the vibron model based on the spectrum generating algebra U(3). Complexity measures (in terms of the Rényi entropies) have been calculated for different values of the control parameter for the ground state of this model giving sharp signatures of the quantum shape-phase transition from linear to bent molecules. PMID:24948526

  20. Realist complex intervention science: Applying realist principles across all phases of the Medical Research Council framework for developing and evaluating complex interventions

    PubMed Central

    Fletcher, Adam; Jamal, Farah; Moore, Graham; Evans, Rhiannon E.; Murphy, Simon; Bonell, Chris

    2016-01-01

    The integration of realist evaluation principles within randomised controlled trials (‘realist RCTs’) enables evaluations of complex interventions to answer questions about what works, for whom and under what circumstances. This allows evaluators to better develop and refine mid-level programme theories. However, this is only one phase in the process of developing and evaluating complex interventions. We describe and exemplify how social scientists can integrate realist principles across all phases of the Medical Research Council framework. Intervention development, modelling, and feasibility and pilot studies need to theorise the contextual conditions necessary for intervention mechanisms to be activated. Where interventions are scaled up and translated into routine practice, realist principles also have much to offer in facilitating knowledge about longer-term sustainability, benefits and harms. Integrating a realist approach across all phases of complex intervention science is vital for considering the feasibility and likely effects of interventions for different localities and population subgroups. PMID:27478401

  1. DNA-Encoded Solid-Phase Synthesis: Encoding Language Design and Complex Oligomer Library Synthesis

    PubMed Central

    2015-01-01

    The promise of exploiting combinatorial synthesis for small molecule discovery remains unfulfilled due primarily to the “structure elucidation problem”: the back-end mass spectrometric analysis that significantly restricts one-bead-one-compound (OBOC) library complexity. The very molecular features that confer binding potency and specificity, such as stereochemistry, regiochemistry, and scaffold rigidity, are conspicuously absent from most libraries because isomerism introduces mass redundancy and diverse scaffolds yield uninterpretable MS fragmentation. Here we present DNA-encoded solid-phase synthesis (DESPS), comprising parallel compound synthesis in organic solvent and aqueous enzymatic ligation of unprotected encoding dsDNA oligonucleotides. Computational encoding language design yielded 148 thermodynamically optimized sequences with Hamming string distance ≥ 3 and total read length <100 bases for facile sequencing. Ligation is efficient (70% yield), specific, and directional over 6 encoding positions. A series of isomers served as a testbed for DESPS’s utility in split-and-pool diversification. Single-bead quantitative PCR detected 9 × 104 molecules/bead and sequencing allowed for elucidation of each compound’s synthetic history. We applied DESPS to the combinatorial synthesis of a 75 645-member OBOC library containing scaffold, stereochemical and regiochemical diversity using mixed-scale resin (160-μm quality control beads and 10-μm screening beads). Tandem DNA sequencing/MALDI-TOF MS analysis of 19 quality control beads showed excellent agreement (<1 ppt) between DNA sequence-predicted mass and the observed mass. DESPS synergistically unites the advantages of solid-phase synthesis and DNA encoding, enabling single-bead structural elucidation of complex compounds and synthesis using reactions normally considered incompatible with unprotected DNA. The widespread availability of inexpensive oligonucleotide synthesis, enzymes, DNA sequencing, and

  2. Low temperature pathways to Chevrel phases via reduced molybdenum sulfide cluster complexes

    NASA Astrophysics Data System (ADS)

    Shane, H.

    1993-03-01

    The initial cluster compound, Na(2y)Mo(6)S(8+y) py(sub x), was discovered by reacting Mo(6)Cl(12) with higher stoichiometries of sodium hydrosulfide and sodium butoxide in butanol/pyridine. This compound can subsequently undergo ligand exchange reactions to form a variety of cluster complexes. Single-crystal structure determinations are reported for the pyridine (py), piperidine (pip), and pyrrolidine (pyrr) complexes: triclinic Mo(6)S(8)(PY)(6) (center dot) 1.65py, cubic Mo(6)S(8)(py)(6) (center dot) 2py, Mo(6)S(8)(pip)(6) (center dot) 7pip, and Mo(6)S(8) (pyrr)(6) (center dot) 1pyrr. Delegation of the cluster complexes was explored. Direct heating under dynamic vacuum led to incomplete delegation. Reactions with tin and lead resulted in formation of corresponding Chevrel phase compounds along with MoS(2). Thermolysis reactions in the presence of flowing ammonia gas resulted in further delegation than was evidenced for reactions explored in vacuo. Solution reactions with strong acids were studied in an attempt to protonate the ligands and thus make them better leaving groups only limited success was achieved. A new preparative route was developed for ternary molybdenum sulfides. Cation exchange reactions with Na(2y)Mo(6)S(8+y)(MeOH)(x) were used to form the cobalt, tin, lead, and holmium compounds. Preliminary hydrodesulfurization studies on the sodium and cobalt compounds showed that they possess larger surface areas and thiophene conversion percentages than Chevrel phases, but a lower HDS rate.

  3. Applications of Wang-Landau sampling to determine phase equilibria in complex fluids

    NASA Astrophysics Data System (ADS)

    Ganzenmüller, Georg; Camp, Philip J.

    2007-10-01

    Applications of the Wang-Landau algorithm for simulating phase coexistence at fixed temperature are presented. The number density is sampled using either volume scaling or particle insertion/deletion. The resulting algorithms, while being conceptually easy, are of comparable efficiency to existing multicanonical methods but with the advantage that neither the chemical potential nor the pressure at phase coexistence has to be estimated in advance of the simulation. First, we benchmark the algorithm against literature results for the vapor-liquid transition in the Lennard-Jones fluid. We then demonstrate the general applicability of the algorithm by studying vapor-liquid coexistence in two examples of complex fluids: charged soft spheres, which exhibit a transition similar to that in the restricted primitive model of ionic fluids, being characterized by strong ion pairing in the vapor phase; and Stockmayer fluids with high dipole strengths, in which the constituent particles aggregate to form chains, and for which the very existence of a transition has been widely debated. Finally, we show that the algorithm can be used to locate a weak isotropic-nematic transition in a fluid of Gay-Berne mesogens.

  4. Applications of Wang-Landau sampling to determine phase equilibria in complex fluids.

    PubMed

    Ganzenmüller, Georg; Camp, Philip J

    2007-10-21

    Applications of the Wang-Landau algorithm for simulating phase coexistence at fixed temperature are presented. The number density is sampled using either volume scaling or particle insertion/deletion. The resulting algorithms, while being conceptually easy, are of comparable efficiency to existing multicanonical methods but with the advantage that neither the chemical potential nor the pressure at phase coexistence has to be estimated in advance of the simulation. First, we benchmark the algorithm against literature results for the vapor-liquid transition in the Lennard-Jones fluid. We then demonstrate the general applicability of the algorithm by studying vapor-liquid coexistence in two examples of complex fluids: charged soft spheres, which exhibit a transition similar to that in the restricted primitive model of ionic fluids, being characterized by strong ion pairing in the vapor phase; and Stockmayer fluids with high dipole strengths, in which the constituent particles aggregate to form chains, and for which the very existence of a transition has been widely debated. Finally, we show that the algorithm can be used to locate a weak isotropic-nematic transition in a fluid of Gay-Berne mesogens. PMID:17949170

  5. Structural evolution of polyelectrolyte-complex-core micelles and ordered-phase bulk materials

    NASA Astrophysics Data System (ADS)

    Tirrell, Matthew; Krogstad, Daniel; Kramer, Edward

    2015-03-01

    The kinetics of formation and structural evolution of novel polyelectrolyte complex materials formed by the assembly of water-soluble di- and tri-block copolymers, with one neutral block and one block either cationic or anionic, have been investigated. The mechanism and speed of the assembly process, and the organization of these domains, were probed using dynamic mechanical spectroscopy and small angle X-ray scattering (SAXS). SAXS revealed that the equilibrium morphologies of both the di-block copolymer and the tri-block copolymer materials were generally qualitatively the same with some apparent quantitative differences in phase boundaries, possibly attributable to lack of full equilibration. Slow kinetics and difficulties in reaching equilibrium phase structures, especially in tri-block materials, is a principal message of this article. Detailed analysis of the SAXS data revealed that the tri-block copolymer materials formed ordered phases via a nucleation and growth pathway and that the addition of small amounts (~20%) of corresponding di-block copolymers increased the rate of structure formation and enhanced several key physical properties. This work was supported by the U.S. Department of Energy Office of Science Program in Basic Energy Sciences, Materials Sciences and Engineering Division.

  6. Gas Phase Uranyl Activation: Formation of a Uranium Nitrosyl Complex from Uranyl Azide

    SciTech Connect

    Gong, Yu; De Jong, Wibe A.; Gibson, John K.

    2015-05-13

    Activation of the oxo bond of uranyl, UO22+, was achieved by collision induced dissociation (CID) of UO2(N3)Cl2– in a quadrupole ion trap mass spectrometer. The gas phase complex UO2(N3)Cl2– was produced by electrospray ionization of solutions of UO2Cl2 and NaN3. CID of UO2(N3)Cl2– resulted in the loss of N2 to form UO(NO)Cl2–, in which the “inert” uranyl oxo bond has been activated. Formation of UO2Cl2– via N3 loss was also observed. Density functional theory computations predict that the UO(NO)Cl2– complex has nonplanar Cs symmetry and a singlet ground state. Analysis of the bonding of the UO(NO)Cl2– complex shows that the side-on bonded NO moiety can be considered as NO3–, suggesting a formal oxidation state of U(VI). Activation of the uranyl oxo bond in UO2(N3)Cl2– to form UO(NO)Cl2– and N2 was computed to be endothermic by 169 kJ/mol, which is energetically more favorable than formation of NUOCl2– and UO2Cl2–. The observation of UO2Cl2– during CID is most likely due to the absence of an energy barrier for neutral ligand loss.

  7. Novel complex MAD phasing and RNase H structural insights using selenium oligonucleotides

    PubMed Central

    Abdur, Rob; Gerlits, Oksana O.; Gan, Jianhua; Jiang, Jiansheng; Salon, Jozef; Kovalevsky, Andrey Y.; Chumanevich, Alexander A.; Weber, Irene T.; Huang, Zhen

    2014-01-01

    The crystal structures of protein–nucleic acid complexes are commonly determined using selenium-derivatized proteins via MAD or SAD phasing. Here, the first protein–nucleic acid complex structure determined using selenium-derivatized nucleic acids is reported. The RNase H–RNA/DNA complex is used as an example to demonstrate the proof of principle. The high-resolution crystal structure indicates that this selenium replacement results in a local subtle unwinding of the RNA/DNA substrate duplex, thereby shifting the RNA scissile phosphate closer to the transition state of the enzyme-catalyzed reaction. It was also observed that the scissile phosphate forms a hydrogen bond to the water nucleophile and helps to position the water molecule in the structure. Consistently, it was discovered that the substitution of a single O atom by a Se atom in a guide DNA sequence can largely accelerate RNase H catalysis. These structural and catalytic studies shed new light on the guide-dependent RNA cleavage. PMID:24531469

  8. Gas phase uranyl activation: formation of a uranium nitrosyl complex from uranyl azide.

    PubMed

    Gong, Yu; de Jong, Wibe A; Gibson, John K

    2015-05-13

    Activation of the oxo bond of uranyl, UO2(2+), was achieved by collision induced dissociation (CID) of UO2(N3)Cl2(-) in a quadrupole ion trap mass spectrometer. The gas phase complex UO2(N3)Cl2(-) was produced by electrospray ionization of solutions of UO2Cl2 and NaN3. CID of UO2(N3)Cl2(-) resulted in the loss of N2 to form UO(NO)Cl2(-), in which the "inert" uranyl oxo bond has been activated. Formation of UO2Cl2(-) via N3 loss was also observed. Density functional theory computations predict that the UO(NO)Cl2(-) complex has nonplanar Cs symmetry and a singlet ground state. Analysis of the bonding of the UO(NO)Cl2(-) complex shows that the side-on bonded NO moiety can be considered as NO(3-), suggesting a formal oxidation state of U(VI). Activation of the uranyl oxo bond in UO2(N3)Cl2(-) to form UO(NO)Cl2(-) and N2 was computed to be endothermic by 169 kJ/mol, which is energetically more favorable than formation of NUOCl2(-) and UO2Cl2(-). The observation of UO2Cl2(-) during CID is most likely due to the absence of an energy barrier for neutral ligand loss. PMID:25906363

  9. Gas-liquid two-phase flow structure in the multi-scale weighted complexity entropy causality plane

    NASA Astrophysics Data System (ADS)

    Tang, Yi; Zhao, An; Ren, Ying-yu; Dou, Fu-Xiang; Jin, Ning-De

    2016-05-01

    The multi-scale weighted complexity entropy causality plane (MS-WCECP) is proposed for characterizing the physical structure of complex system. Firstly we use the method to investigate typical nonlinear time series. Compared with the multi-scale complexity entropy causality plane (MS-CECP), the MS-WCECP can not only uncover the dynamic information loss of complex system with the increase of scale, but also can characterize the complexity of nonlinear dynamic system. In particular, the algorithm of MS-WCECP performs strong anti-noise ability. Then we calculate the MS-WCECP for the conductance fluctuating signals measured from vertical upward gas-liquid two-phase flow experiments in a small diameter pipe, the results demonstrate that the MS-WCECP is a useful approach for exploring the stability and complexity in gas-liquid two-phase flows.

  10. Photoreactions in the gas-phase complexes of Mg(*+)-dioxanes.

    PubMed

    Liu, Haichuan; Hu, Yihua; Yang, Shihe; Guo, Wenyue; Fu, Qingtao; Wang, Ling

    2006-04-01

    Photoreactions in the gas-phase complexes Mg(*+)(1,4-dioxane) (1) and Mg(*+)(1,3-dioxane) (1M) have been examined in the wavelength region of 230-440 nm. Photoproduct assignments are facilitated with the help of deuterium substitution experiments. The main energy relaxation channel for both photoexcited complexes is the evaporation of Mg(*+). Also observed from 1 are rich photoproducts with m/z 28, 41, 54-58, 67, 69, and 88; the most abundant one at m/z 54 is designated to Mg(*+)(O=CH(2)). In marked contrast, the photolysis of 1M yields only Mg(*+)(O=CH(2)) other than Mg(*+). Density functional calculations are performed to obtain optimized geometries and potential energy surfaces of 1 and 1M. Although Mg(*+)(chair-1,4-C(4)H(8)O(2)) (1a) and Mg(*+)(boat-1,4-C(4)H(8)O(2)) (1b) are comparable in energy, the much better agreement of the experimental action spectrum of Mg(*+)(1,4-C(4)H(8)O(2)) with the calculated absorption spectrum of 1a than with that of 1b indicates the predominance of 1a in the source due to the stability of the chair-1,4-dioxane. For photoreactions, the C-O bond is found to be much more prone to rupture than the C-C bond due to the coordination of O to Mg(+) in the parent complexes. Photoreaction mechanisms are discussed in terms of two key insertion complexes, which rationalize all of the observed photoproducts. PMID:16571042

  11. In vivoimaging of human vasculature in the chorioretinal complex using phase-variance contrast method with phase-stabilized 1 - μ m swept-source optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Poddar, Raju; Kim, Dae Yu; Werner, John S.; Zawadzki, Robert J.

    2014-12-01

    We present a noninvasive phase-variance (pv)-based motion contrast method for depth-resolved imaging of the human chorioretinal complex microcirculation with a newly developed phase-stabilized high speed (100-kHz A-scans/s) 1-μm swept-source optical coherence tomography (SSOCT) system. Compared to our previous spectral-domain (spectrometer based) pv-spectral domain OCT (SDOCT) system, this system has the advantages of higher sensitivity, reduced fringe wash-out for high blood flow speeds and deeper penetration in choroid. High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. This process does not require additional calibration hardware and complex numerical procedures. Our phase stabilization method is simple and can be employed in a variety of SSOCT systems. Examples of vasculature in the chorioretinal complex imaged by pv-SSOCT from normal as well as diseased eyes are presented and compared to retinal images of the same subjects acquired with fluorescein angiography and indocyanine green angiography. Observations of morphology of vascular perfusion in chorioretinal complex visualized by our method are listed.

  12. An HPLC chromatographic framework to analyze the β-cyclodextrin/solute complexation mechanism using a carbon nanotube stationary phase.

    PubMed

    Aljhni, Rania; Andre, Claire; Lethier, Lydie; Guillaume, Yves Claude

    2015-11-01

    A carbon nanotube (CNT) stationary phase was used for the first time to study the β-cyclodextrin (β-CD) solute complexation mechanism using high performance liquid chromatography (HPLC). For this, the β-CD was added at various concentrations in the mobile phase and the effect of column temperature was studied on both the retention of a series of aniline and benzoic acid derivatives with the CNT stationary phase and their complexation mechanism with β-CD. A decrease in the solute retention factor was observed for all the studied molecules without change in the retention order. The apparent formation constant KF of the inclusion complex β-CD/solute was determined at various temperatures. Our results showed that the interaction of β-CD with both the mobile phase and the stationary phase interfered in the complex formation. The enthalpy and entropy of the complex formation (ΔHF and ΔSF) between the solute molecule and CD were determined using a thermodynamic approach. Negative enthalpies and entropies indicated that the inclusion process of the studied molecule in the CD cavity was enthalpically driven and that the hydrogen bonds between carboxylic or aniline groups and the functional groups on the β-CD rim play an important role in the complex formation. PMID:26452814

  13. Complex phase error and motion estimation in synthetic aperture radar imaging

    NASA Astrophysics Data System (ADS)

    Soumekh, M.; Yang, H.

    1991-06-01

    Attention is given to a SAR wave equation-based system model that accurately represents the interaction of the impinging radar signal with the target to be imaged. The model is used to estimate the complex phase error across the synthesized aperture from the measured corrupted SAR data by combining the two wave equation models governing the collected SAR data at two temporal frequencies of the radar signal. The SAR system model shows that the motion of an object in a static scene results in coupled Doppler shifts in both the temporal frequency domain and the spatial frequency domain of the synthetic aperture. The velocity of the moving object is estimated through these two Doppler shifts. It is shown that once the dynamic target's velocity is known, its reconstruction can be formulated via a squint-mode SAR geometry with parameters that depend upon the dynamic target's velocity.

  14. The little elongation complex functions at initiation and elongation phases of snRNA gene transcription.

    PubMed

    Hu, Deqing; Smith, Edwin R; Garruss, Alexander S; Mohaghegh, Nima; Varberg, Joseph M; Lin, Chengqi; Jackson, Jessica; Gao, Xin; Saraf, Anita; Florens, Laurence; Washburn, Michael P; Eissenberg, Joel C; Shilatifard, Ali

    2013-08-22

    The small nuclear RNA (snRNA) genes have been widely used as a model system for understanding transcriptional regulation due to the unique aspects of their promoter structure, selectivity for either RNA polymerase (Pol) II or III, and because of their unique mechanism of termination that is tightly linked with the promoter. Recently, we identified the little elongation complex (LEC) in Drosophila that is required for the expression of Pol II-transcribed snRNA genes. Here, using Drosophila and mammalian systems, we provide genetic and molecular evidence that LEC functions in at least two phases of snRNA transcription: an initiation step requiring the ICE1 subunit, and an elongation step requiring ELL. PMID:23932780

  15. The Little Elongation Complex functions at initiation and elongation phases of snRNA gene transcription

    PubMed Central

    Hu, Deqing; Smith, Edwin R.; Garruss, Alexander S.; Mohaghegh, Nima; Varberg, Joseph M.; Lin, Chengqi; Jackson, Jessica; Gao, Xin; Saraf, Anita; Florens, Laurence; Washburn, Michael P.; Eissenberg, Joel C.; Shilatifard, Ali

    2014-01-01

    SUMMARY The small nuclear RNA (snRNA) genes have been widely used as a model system for understanding transcriptional regulation due to the unique aspects of their promoter structure, selectivity for either RNA Polymerase (Pol) II or III, and because of their unique mechanism of termination that is tightly linked with the promoter. Recently, we identified the Little Elongation Complex (LEC) in Drosophila that is required for the expression of Pol II-transcribed snRNA genes. Here, using Drosophila and mammalian systems, we provide genetic and molecular evidence that LEC functions in at least two phases of snRNA transcription: an initiation step requiring the ICE1 subunit, and an elongation step requiring ELL. PMID:23932780

  16. Automated pathologies detection in retina digital images based on complex continuous wavelet transform phase angles.

    PubMed

    Lahmiri, Salim; Gargour, Christian S; Gabrea, Marcel

    2014-10-01

    An automated diagnosis system that uses complex continuous wavelet transform (CWT) to process retina digital images and support vector machines (SVMs) for classification purposes is presented. In particular, each retina image is transformed into two one-dimensional signals by concatenating image rows and columns separately. The mathematical norm of phase angles found in each one-dimensional signal at each level of CWT decomposition are relied on to characterise the texture of normal images against abnormal images affected by exudates, drusen and microaneurysms. The leave-one-out cross-validation method was adopted to conduct experiments and the results from the SVM show that the proposed approach gives better results than those obtained by other methods based on the correct classification rate, sensitivity and specificity. PMID:26609393

  17. Monitoring the formation of carbide crystal phases during the thermal decomposition of 3d transition metal dicarboxylate complexes

    SciTech Connect

    Huba, ZJ; Carpenter, EE

    2014-06-06

    Single molecule precursors can help to simplify the synthesis of complex alloys by minimizing the amount of necessary starting reagents. However, single molecule precursors are time consuming to prepare with very few being commercially available. In this study, a simple precipitation method is used to prepare Fe, Co, and Ni fumarate and succinate complexes. These complexes were then thermally decomposed in an inert atmosphere to test their efficiency as single molecule precursors for the formation of metal carbide phases. Elevated temperature X-ray diffraction was used to identify the crystal phases produced upon decomposition of the metal dicarboxylate complexes. Thermogravimetric analysis coupled with an infrared detector was used to identify the developed gaseous decomposition products. All complexes tested showed a reduction from the starting M2+ oxidation state to the M oxidation state, upon decomposition. Also, each complex tested showed CO2 and H2O as gaseous decomposition products. Nickel succinate, iron succinate, and iron fumarate complexes were found to form carbide phases upon decomposition. This proves that transition metal dicarboxylate salts can be employed as efficient single molecule precursors for the formation of metal carbide crystal phases.

  18. Gas Phase Chemistry and Molecular Complexity: How Far Do They Go?

    NASA Astrophysics Data System (ADS)

    Balucani, Nadia

    2016-07-01

    The accumulation of organic molecules of increasing complexity is believed to be an important step toward the emergence of life. But how massive organic synthesis could occur in primitive Earth, i.e. a water-dominated environment, is a matter of debate. Two alternative theories have been suggested so far: endogenous and exogenous synthesis. In the first theory, the synthesis of simple organic molecules having a strong prebiotic potential (simple prebiotic molecules SPMs, such as H2CO, HCN, HC3N, NH2CHO) occurred directly on our planet starting from simple parent molecules of the atmosphere, liquid water and various energy sources. Miller's experiment was a milestone in this theory, but it was later recognized that the complexity of a planet cannot be reproduced in a single laboratory experiment. Some SPMs have been identified in the N2-dominated atmosphere of Titan (a massive moon of Saturn), which is believed to be reminiscent of the primitive terrestrial atmosphere. As such, the atmosphere of Titan represents a planetary scale laboratory for the comprehension of SPM formation in an environment close enough to primitive Earth and is the current frontier in the endogenous theory exploration. In the exogenous theory, SPMs came from space, the carriers being comets, asteroids and meteorites. The rationale behind this suggestion is that plenty of SPMs have been observed in interstellar clouds (ISCs), including star-forming regions, and in small bodies like comets, asteroids and meteorites. Therefore, the basic idea is that SPMs were formed in the solar nebula, preserved during the early phases of the Solar System formation in the body of comets/asteroids/meteorites and finally delivered to Earth by cometary and meteoritic falls. In this contribution, the status of our knowledge on how SPMs can be formed in the gas phase, either in the primitive terrestrial atmosphere or in the cold nebula from which the Solar System originated, will be presented. Particular attention

  19. Phase behavior of polyion-surfactant ion complex salts: effects of surfactant chain length and polyion length.

    PubMed

    Svensson, Anna; Norrman, Jens; Piculell, Lennart

    2006-06-01

    The aqueous phase behavior of a series of complex salts, containing cationic surfactants with polymeric counterions, has been investigated by visual inspection and small-angle X-ray scattering (SAXS). The salts were alkyltrimethylammonium polyacrylates, CxTAPAy, based on all combinations of five surfactant chain lengths (C6, C8, C10, C12, and C16) and two lengths of the polyacrylate chain (30 and 6 000 repeating units). At low water contents, all complex salts except C6TAPA6000 formed hexagonal and/or cubic Pm3n phases, with the hexagonal phase being favored by lower water contents. The aggregate dimensions in the liquid crystalline phases changed with the surfactant chain length. The determined micellar aggregation numbers of the cubic phases indicated that the micelles were only slightly aspherical. At high water contents, the C6TAPAy salts were miscible with water, whereas the other complex salts featured wide miscibility gaps with a concentrated phase in equilibrium with a (sometimes very) dilute aqueous solution. Thus, the attraction between oppositely charged surfactant aggregates and polyions decreases with decreasing surfactant chain length, and with decreasing polyion length, resulting in an increased miscibility with water. The complex salt with the longest surfactant chains and polyions gave the widest miscibility gap, with a concentrated hexagonal phase in equilibrium with almost pure water. A decrease in the attraction led to cubic-micellar and micellar-micellar coexistence in the miscibility gap and to an increasing concentration of the complex salt in the dilute phase. For each polyion length, the mixtures for the various surfactant chain lengths were found to conform to a global phase diagram, where the surfactant chain length played the role of an interaction parameter. PMID:16722736

  20. Natural history of chronic hepatitis B: Phases in a complex relationship

    PubMed Central

    Croagh, Catherine MN; Lubel, John S

    2014-01-01

    Chronic hepatitis B (CHB) is a condition of global prevalence and its sequelae include cirrhosis and hepatocellular carcinoma. The natural history of CHB is a complex interplay of virological, environmental and host factors. The dynamic relationship between the virus and host evolves over the duration of the infection and different phases of the disease have been observed and described. These have been conceptualized in terms of the state of balance between the host immune system and the hepatitis B virus and have been given the labels immune tolerant, immune clearance, immune control and immune escape although other nomenclature is also used. Host factors, such as age at infection, determine progression to chronicity. Virological factors including hepatitis B viral load, mutations and genotype also have an impact on the adverse outcomes of the infection, as do hepatotoxic cofactors such as alcohol. Our understanding of the natural history of CHB has evolved significantly over the past few decades and characterizing the phase of disease of CHB remains an integral part of managing this virus in the clinic. PMID:25132755

  1. One-Step Liquid-Phase Synthesis of Carbon Nanotubes with Catalyst Precursors of Organometallic Complexes

    NASA Astrophysics Data System (ADS)

    Yamagiwa, Kiyofumi; Kikitsu, Tomoka; Yamashita, Shunsuke; Kuwano, Jun

    2011-01-01

    This paper describes a simple, low cost one-step liquid-phase process for the synthesis of highly aligned carbon nanotube (CNT) arrays (HACNTAs). Highly pure HACNTAs were grown on a stainless steel substrate by resistance-heating in methanol solution containing one of the organometallic complex catalyst precursors, ferrocene Fe(C5H5)2 and iron pentacarbonyl Fe(CO)5. Effects of the catalyst precursors on the formation and morphologies of HACNTAs were examined. A small amount of non-aligned multi-walled CNTs (MWCNTs) were grown from 1 mM Fe(C5H5)2 methanol solution. Highly pure HACNTAs composed of MWCNTs were readily grown from 10 and 40 mM Fe(C5H5)2 methanol solutions by this one-step liquid-phase process. From the Fe(CO)5 methanol solution, HACNTAs were prepared even at a very low Fe(CO)5 concentration of 0.01 mM, which was about 1/1000 lower than that of Fe(C5H5)2. The optimal low concentration is attributed to the low decomposition temperature of Fe(CO)5.

  2. Design of off-axis mirrors for the phase-induced amplitude apodization complex mask coronagraph

    NASA Astrophysics Data System (ADS)

    Pluzhnik, Eugene; Guyon, Olivier; Belikov, Ruslan; Bendek, Eduardo

    2016-01-01

    The phase-induced amplitude apodization complex mask coronagraph (PIAACMC) provides an efficient way to control diffraction propagation effects caused by the central obstruction/segmented mirrors of the telescope. PIAACMC can be optimized in a way that takes into account both chromatic diffraction effects caused by the telescope obstructed aperture and the tip-tilt sensitivity of the coronagraph. As a result, unlike classic phase-induced amplitude apodization (PIAA), the PIAACMC mirror shapes are often slightly asymmetric even for an on-axis configuration and require more care in calculating off-axis shapes when an off-axis configuration is preferred. A method to design off-axis PIAA mirror shapes given an on-axis mirror design is presented. The algorithm is based on geometrical ray tracing and is able to calculate off-axis PIAA mirror shapes for an arbitrary geometry of the input and output beams. The method is demonstrated using the third generation PIAACMC design for WFIRST-AFTA telescope. Geometrical optics design issues related to the off-axis diffraction propagation effects are also discussed.

  3. Complex magnetic phases in non-centrosymmetric heavy fermion CeCoGe3

    NASA Astrophysics Data System (ADS)

    Wu, Shan; Stock, Chris; Petrovic, Cedomir; Rodriguez-Rivera, J. A.; Broholm, Collin

    The non-centrosymmetric nature of the tetragonal heavy fermion system CeCoGe3 has attracted much interest in the high pressure superconducting state of the material. We have explored the related ambient pressure magnetism using neutron scattering. There are three successive phase transitions at TN 1 ~ 21 K , TN 2 ~ 12 K and TN 3 ~ 8 K. The upper transition greatly enhances the susceptibility and there are meta-magnetic transitions in the lower T phases. We confirmed the previously determined AFM spin structure for TN 2 < T complex commensurate structure that can be described as intertwined antiferromagnetic segments. We also report inelastic magnetic neutron scattering, which is dominated by the periodicity of the chemical cell rather than the magnetic unit cell. The work at IQM was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Material Sciences and Engineering, under Grant No. DEFG02-08ER46544.

  4. Discontinuous phase transition in a core contact process on complex networks

    NASA Astrophysics Data System (ADS)

    Chae, Huiseung; Yook, Soon-Hyung; Kim, Yup

    2015-02-01

    To understand the effect of generalized infection processes, we suggest and study the core contact process (CCP) on complex networks. In CCP an uninfected node is infected when at least k different infected neighbors of the node select the node for the infection. The healing process is the same as that of the normal CP. It is analytically and numerically shown that discontinuous transitions occur in CCP on random networks and scale-free networks depending on infection rate and initial density of infected nodes. The discontinuous transitions include hybrid transitions with β = 1/2 and β = 1. The asymptotic behavior of the phase boundary related to the initial density is found analytically and numerically. The mapping between CCP with k and static (k+1)-core percolation is supposed from the (k+1)-core structure in the active phase and the hybrid transition with β = 1/2. From these properties of CCP one can see that CCP is one of the dynamical processes for the k-core structure on real networks.

  5. A Screening Approach for the Discovery of Mechanochromic Gold(I) Isocyanide Complexes with Crystal-to-Crystal Phase Transitions.

    PubMed

    Seki, Tomohiro; Takamatsu, Yuki; Ito, Hajime

    2016-05-18

    Mechanoinduced phase transitions of emissive organic crystalline materials have received much attention. Although a variety of such luminescent mechanochromic compounds have been reported, it is challenging to develop mechanochromic compounds with crystal-to-crystal phase transitions in which precise structural information about molecular arrangements can be obtained. Here, we report a screening approach to explore mechanochromic compounds exhibiting a crystal-to-crystal phase transition. We prepared 48 para-substituted (R(1)) phenyl[para-substituted (R(2)) phenyl isocyanide]gold(I) complexes designated R(1)-R(2) (six R(1) and eight R(2) substituents) and then performed three-step screening experiments. The first screening step was selection of emissive complexes under UV light, which gave 37 emissive R(1)-R(2) complexes. The second screening step involved evaluation of the mechanochromic properties by emission spectroscopy. Twenty-eight complexes were found to be mechanochromic. The third screening step involved preparation of single crystals, reprecipitated powders, and ground powders of the 28 mechanochromic R(1)-R(2) complexes. The changes in the powder diffraction patterns of these complexes induced by mechanical stimulation were investigated. Two compounds exhibited a crystal-to-crystal phase transition upon mechanical stimulation, including the previously reported H-H complex. Single crystals of the as-prepared and ground forms of the newly discovered CF3-CN complex were obtained. Density functional theory calculations indicated that the mechanoinduced red-shifted emission of CF3-CN is caused by formation of aurophilic interactions. Comparison of the crystal structures of CF3-CN with those of the other complexes suggests that the weaker intermolecular interactions in the as-prepared form are an important structural factor for the observed mechanoinduced crystal-to-crystal phase transition. PMID:27070308

  6. Molecular recognition using corona phase complexes made of synthetic polymers adsorbed on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhang, Jingqing; Landry, Markita P.; Barone, Paul W.; Kim, Jong-Ho; Lin, Shangchao; Ulissi, Zachary W.; Lin, Dahua; Mu, Bin; Boghossian, Ardemis A.; Hilmer, Andrew J.; Rwei, Alina; Hinckley, Allison C.; Kruss, Sebastian; Shandell, Mia A.; Nair, Nitish; Blake, Steven; Şen, Fatih; Şen, Selda; Croy, Robert G.; Li, Deyu; Yum, Kyungsuk; Ahn, Jin-Ho; Jin, Hong; Heller, Daniel A.; Essigmann, John M.; Blankschtein, Daniel; Strano, Michael S.

    2013-12-01

    Understanding molecular recognition is of fundamental importance in applications such as therapeutics, chemical catalysis and sensor design. The most common recognition motifs involve biological macromolecules such as antibodies and aptamers. The key to biorecognition consists of a unique three-dimensional structure formed by a folded and constrained bioheteropolymer that creates a binding pocket, or an interface, able to recognize a specific molecule. Here, we show that synthetic heteropolymers, once constrained onto a single-walled carbon nanotube by chemical adsorption, also form a new corona phase that exhibits highly selective recognition for specific molecules. To prove the generality of this phenomenon, we report three examples of heteropolymer-nanotube recognition complexes for riboflavin, L-thyroxine and oestradiol. In each case, the recognition was predicted using a two-dimensional thermodynamic model of surface interactions in which the dissociation constants can be tuned by perturbing the chemical structure of the heteropolymer. Moreover, these complexes can be used as new types of spatiotemporal sensors based on modulation of the carbon nanotube photoemission in the near-infrared, as we show by tracking riboflavin diffusion in murine macrophages.

  7. Variational regularization of complex deautoconvolution and phase retrieval in ultrashort laser pulse characterization

    NASA Astrophysics Data System (ADS)

    Anzengruber, Stephan W.; Bürger, Steven; Hofmann, Bernd; Steinmeyer, Günter

    2016-03-01

    The SD-SPIDER method for the characterization of ultrashort laser pulses requires the solution of a nonlinear integral equation of autoconvolution type with a device-based kernel function. Taking into account the analytical background of a variational regularization approach for solving the corresponding ill-posed operator equation formulated in complex-valued L 2-spaces over finite real intervals, we suggest and evaluate numerical procedures using NURBS and the TIGRA method for calculating the regularized solutions in a stable manner. In this context, besides the complex deautoconvolution problem with noisy but full data, a phase retrieval problem is introduced which adapts to the experimental state of the art in laser optics. For the treatment of this problem facet, which is formulated as a tensor product operator equation, we derive the well-posedness of variational regularization methods. Case studies with synthetic and real optical data show the capability of the implemented approach as well as its limitations due to measurement deficits.

  8. EXAFS Phase Retrieval Solution Tracking for Complex Multi-Component System: Synthesized Topological Inverse Computation

    NASA Astrophysics Data System (ADS)

    Lee, Jay Min; Yang, Dong-Seok; Bunker, Grant B.

    2013-04-01

    Using the FEFF kernel A(k,r), we describe the inverse computation from χ(k)-data to g(r)-solution in terms of a singularity regularization method based on complete Bayesian statistics process. In this work, we topologically decompose the system-matched invariant projection operators into two distinct types, (A+AA+A) and (AA+AA+), and achieved Synthesized Topological Inversion Computation (STIC), by employing a 12-operator-closed-loop emulator of the symplectic transformation. This leads to a numerically self-consistent solution as the optimal near-singular regularization parameters are sought, dramatically suppressing instability problems connected with finite precision arithmetic in ill-posed systems. By statistically correlating a pair of measured data, it was feasible to compute an optimal EXAFS phase retrieval solution expressed in terms of the complex-valued χ(k), and this approach was successfully used to determine the optimal g(r) for a complex multi-component system.

  9. Sampling strategies for accurate computational inferences of gametic phase across highly polymorphic major histocompatibility complex loci

    PubMed Central

    2011-01-01

    Background Genes of the Major Histocompatibility Complex (MHC) are very popular genetic markers among evolutionary biologists because of their potential role in pathogen confrontation and sexual selection. However, MHC genotyping still remains challenging and time-consuming in spite of substantial methodological advances. Although computational haplotype inference has brought into focus interesting alternatives, high heterozygosity, extensive genetic variation and population admixture are known to cause inaccuracies. We have investigated the role of sample size, genetic polymorphism and genetic structuring on the performance of the popular Bayesian PHASE algorithm. To cover this aim, we took advantage of a large database of known genotypes (using traditional laboratory-based techniques) at single MHC class I (N = 56 individuals and 50 alleles) and MHC class II B (N = 103 individuals and 62 alleles) loci in the lesser kestrel Falco naumanni. Findings Analyses carried out over real MHC genotypes showed that the accuracy of gametic phase reconstruction improved with sample size as a result of the reduction in the allele to individual ratio. We then simulated different data sets introducing variations in this parameter to define an optimal ratio. Conclusions Our results demonstrate a critical influence of the allele to individual ratio on PHASE performance. We found that a minimum allele to individual ratio (1:2) yielded 100% accuracy for both MHC loci. Sampling effort is therefore a crucial step to obtain reliable MHC haplotype reconstructions and must be accomplished accordingly to the degree of MHC polymorphism. We expect our findings provide a foothold into the design of straightforward and cost-effective genotyping strategies of those MHC loci from which locus-specific primers are available. PMID:21615903

  10. The gas phase origin of complex organic molecules precursors in prestellar cores

    NASA Astrophysics Data System (ADS)

    Bacmann, A.; Faure, A.

    2016-05-01

    Complex organic molecules (COMs) have long been observed in the warm regions surrounding nascent protostars. The recent discovery of oxygen-bearing COMs like methyl formate or dimethyl ether in prestellar cores (Bacmann et al. [2]), where gas and dust temperatures rarely exceed 10-15 K, has challenged the previously accepted models according to which COM formation relied on the diffusion of heavy radicals on warm (˜30 K) grains. Following these detections, new questions have arisen: do non-thermal processes play a role in increasing radical mobility or should new gas-phase routes be explored? The radicals involved in the formation of the aforementioned COMs, HCO and CH3O represent intermediate species in the grain-surface synthesis of methanol which proceeds via successive hydrogenations of CO molecules in the ice. We present here observations of methanol and its grain-surface precursors HCO, H2CO, CH3O in a sample of prestellar cores and derive their relative abundances. We find that the relative abundances HCO:H2CO:CH3O:CH3OH are constant across the core sample, close to 10:100:1:100. Our results also show that the amounts of HCO and CH3O are consistent with a gas-phase synthesis of these species from H2CO and CH3OH via radical-neutral or ion-molecule reactions followed by dissociative recombinations. Thus, while grain chemistry is necessary to explain the abundances of the parent volatile CH3OH, and possibly H2CO, the reactive species HCO and CH3O might be daughter molecules directly produced in the gas-phase.

  11. Properties of hydrogen and hydrogen-vacancy complexes in the rutile phase of titanium dioxide

    NASA Astrophysics Data System (ADS)

    Filippone, F.; Mattioli, G.; Alippi, P.; Amore Bonapasta, A.

    2009-12-01

    The interaction of atomic H with host atoms and oxygen vacancies (VO) in the rutile phase of the TiO2 metal oxide has been investigated by using density-functional theory-local spin density (DFT-LSD) and DFT-LSD+U theoretical methods. The achieved results show that H in rutile presents quite different and peculiar properties with respect to other semiconductors and metal oxides. It behaves indeed neither as an amphoteric impurity, as it does in Si and GaAs, nor as a shallow donor, as it has been proposed in ZnO. Moreover, H in rutile represents a failure of a theoretical model proposing a universal alignment of the H-induced electronic level in the energy gaps of semiconductors, which predicts a shallow donor behavior of H in ZnO and TiO2 . Present results show indeed that H behaves as a deep donor in rutile and always forms an OH+ complex, independent of the position of the Fermi energy. This very unusual behavior of H can be accounted for by a peculiar property of TiO2 regarding its capability of localizing extra electrons at Ti+3 sites. The electron lost by H can be accommodated indeed by a Ti+4 atom which evolves in a Ti+3 defect. This accounts for the deep behavior of H and implies that the electronic level it induces in the TiO2 energy gap has, actually, a Ti+3 character quite similar to that characterizing an O vacancy (VO) , thus distinguishing H in rutile from H in other semiconductors. Finally, H can form stable H-VO complexes where it takes the place of the missing O atom by forming a bond with a prevailing ionic character, at variance with a multicenter bond model proposed for the same complexes in ZnO.

  12. Physico-Chemical Properties and Phase Behavior of the Ionic Liquid-β-Cyclodextrin Complexes

    PubMed Central

    Rogalski, Marek; Modaressi, Ali; Magri, Pierre; Mutelet, Fabrice; Grydziuszko, Aleksandra; Wlazło, Michał; Domańska, Urszula

    2013-01-01

    The solubility of β-cyclodextrin (β-CD) in ionic liquids (ILs) and the activity coefficients at infinite dilution ( γ13∞) of more than 20 solutes (alkanes, aromatic hydrocarbons, alcohols) were measured in four chosen ionic liquids, their mixtures with β-CD, and in the β-CD at high temperatures from 338 to 398 K using the inverse gas chromatography. The intermolecular interactions, inclusion complexes and the possible increasing of the solubility of β-CD in water using the IL are presented. The solubility of β-CD in ten chosen hydrophobic ILs at the temperature T = 423 K was detected. The solid-liquid phase diagrams (SLE) of {IL (1) + β-CD (2)} binary systems at the high mole fraction of the IL were measured for three systems (1-ethyl-3-methylimidazolium chloride, [EMIM][Cl], 1-ethyl-3-methylimidazolium bromide, [EMIM][Br]; and for 1-butyl-3-methylimidazolium chloride, [BMIM][Cl]). The eutectic points were determined at the high IL concentration for all binary systems. The intermolecular interaction and the possibility of inclusion complexes of the IL and/or solvents with β-CD were discussed. The infrared spectroscopy, IR was used for the description of the intermolecular interactions in the (β-CD + IL) systems. It was shown via the activity coefficients at infinite dilution results that the inclusion complexes are dependent on the temperature. The addition of β-CD to the IL does not improve the selectivity of the separation of the aliphatics from aromatics. PMID:23945559

  13. Spatial cross modulation method using a random diffuser and phase-only spatial light modulator for constructing arbitrary complex fields.

    PubMed

    Shibukawa, Atsushi; Okamoto, Atsushi; Takabayashi, Masanori; Tomita, Akihisa

    2014-02-24

    We propose a spatial cross modulation method using a random diffuser and a phase-only spatial light modulator (SLM), by which arbitrary complex-amplitude fields can be generated with higher spatial resolution and diffraction efficiency than off-axis and double-phase computer-generated holograms. Our method encodes the original complex object as a phase-only diffusion image by scattering the complex object using a random diffuser. In addition, all incoming light to the SLM is consumed for a single diffraction order, making a diffraction efficiency of more than 90% possible. This method can be applied for holographic data storage, three-dimensional displays, and other such applications. PMID:24663718

  14. Bond Activation by Metal-Carbene Complexes in the Gas Phase.

    PubMed

    Zhou, Shaodong; Li, Jilai; Schlangen, Maria; Schwarz, Helmut

    2016-03-15

    "Bare" metal-carbene complexes, when generated in the gas phase and exposed to thermal reactions under (near) single-collision conditions, exhibit rather unique reactivities in addition to the well-known metathesis and cyclopropanation processes. For example, at room temperature the unligated [AuCH2](+) complex brings about efficient C-C coupling with methane to produce C2Hx (x = 4, 6), and the couple [TaCH2](+)/CO2 gives rise to the generation of the acetic acid equivalent CH2═C═O. Entirely unprecedented is the thermal extrusion of a carbon atom from halobenzenes (X = F, Cl, Br, I) by [MCH2](+) (M = La, Hf, Ta, W, Re, Os) and its coupling with the methylene ligand to deliver C2H2 and [M(X)(C5H5)](+). Among the many noteworthy C-N bond-forming processes, the formation of CH3NH2 from [RhCH2](+)/NH3, the generation of CH2═NH2(+) from [MCH2](+)/NH3 (M = Pt, Au), and the production of [PtCH═NH2](+) from [PtCH2](+)/NH3 are of particular interest. The latter species are likely to be involved as intermediates in the platinum-mediated large-scale production of HCN from CH4/NH3 (the DEGUSSA process). In this context, a few examples are presented that point to the operation of co-operative effects even at a molecular level. For instance, in the coupling of CH4 with NH3 by the heteronuclear clusters [MPt](+) (M = coinage metal), platinum is crucial for the activation of methane, while the coinage metal M controls the branching ratio between the C-N bond-forming step and unwanted soot formation. For most of the gas-phase reactions described in this Account, detailed mechanistic insight has been derived from extensive computational work in conjunction with time-honored labeling and advanced mass-spectrometry-based experiments, and often a coherent description of the experimental findings has been achieved. As for some transition metals, in particular those from the third row, the metal-carbene complexes can be formed directly from methane, coupling of the so

  15. Phase-equilibrium modelling of blueschists from the Vestgötabreen Complex (SW Svalbard)

    NASA Astrophysics Data System (ADS)

    Kośmińska, Karolina; Majka, Jarosław; Manecki, Maciej; Lorenz, Henning; Kozub, Gabriela

    2014-05-01

    In Svalbard Archipelago, blueschists are known from Motalafjella area (Oscar II Land). They belong to the Vestgötabreen Complex, which is divided into a Lower (LU) and Upper Unit (UU). The former is composed of high pressure-low temperature (HP-LT) metasediments. The latter consists mainly of blueschists and eclogites. Various radiometric dating yielded an age of c. 470 Ma for the HP-LT metamorphism in the Motalafjella area. The pressure-temperature (P-T) conditions for carpholite-bearing schists from LU have been estimated to c. 16 kbar and 330-450°C (Agard et al., 2005), whereas eclogites from UU indicate peak conditions of 18-24 kbar and 580-640°C (Hirajima et al., 1988). During the fieldwork in 2011, blueschists were also discovered at the western coast of Nordenskiöld Land. They form isolated bodies enclosed within metasedimentary units, but their tectonic position is still under debate. Preliminary P-T estimates indicate peak pressure conditions of c. 17 kbar and 480°C (Kośmińska et al., in revision). The age of metamorphism is unknown, however P-T conditions as well as metamorphic assemblage suggest that the blueschists from Nordenskiöld Land may be an equivalent of these in the Vestgötabreen Complex. Samples of blueschists from UU have been collected on Skipperryggen. They consist mainly of glaucophane, garnet, white micas (phengite and paragonite), rutile, lawsonite and chlorite. The garnet typically forms euhedral to subhedral porphyroblasts which contain voluminous inclusions. Its composition varies from Alm63Prp13Grs22Sps2 in the cores to Alm60Prp19Grs20Sps1 in the rims. The change in chemical zoning is rather gradual. The garnet shows bowl-shaped pyrope profiles and opposite almandine trends. The P-T conditions were estimated using phase equilibrium modeling. Preliminary modeling in the NCKFMMnASHTO system yields peak pressure conditions at c. 20 kbar and 520°C. The estimated P-T conditions for the blueschists from Skipperryggen are in

  16. Solid Phase Biosensors for Arsenic or Cadmium Composed of A trans Factor and cis Element Complex

    PubMed Central

    Siddiki, Mohammad Shohel Rana; Kawakami, Yasunari; Ueda, Shunsaku; Maeda, Isamu

    2011-01-01

    The presence of toxic metals in drinking water has hazardous effects on human health. This study was conducted to develop GFP-based-metal-binding biosensors for on-site assay of toxic metal ions. GFP-tagged ArsR and CadC proteins bound to a cis element, and lost the capability of binding to it in their As- and Cd-binding conformational states, respectively. Water samples containing toxic metals were incubated on a complex of GFP-tagged ArsR or CadC and cis element which was immobilized on a solid surface. Metal concentrations were quantified with fluorescence intensity of the metal-binding states released from the cis element. Fluorescence intensity obtained with the assay significantly increased with increasing concentrations of toxic metals. Detection limits of 1 μg/L for Cd(II) and 5 μg/L for As(III) in purified water and 10 µg/L for Cd(II) and As(III) in tap water and bottled mineral water were achieved by measurement with a battery-powered portable fluorometer after 15-min and 30-min incubation, respectively. A complex of freeze dried GFP-tagged ArsR or CadC binding to cis element was stable at 4 °C and responded to 5 μg/L As(III) or Cd(II). The solid phase biosensors are sensitive, less time-consuming, portable, and could offer a protocol for on-site evaluation of the toxic metals in drinking water. PMID:22346629

  17. Solid phase biosensors for arsenic or cadmium composed of A trans factor and cis element complex.

    PubMed

    Siddiki, Mohammad Shohel Rana; Kawakami, Yasunari; Ueda, Shunsaku; Maeda, Isamu

    2011-01-01

    The presence of toxic metals in drinking water has hazardous effects on human health. This study was conducted to develop GFP-based-metal-binding biosensors for on-site assay of toxic metal ions. GFP-tagged ArsR and CadC proteins bound to a cis element, and lost the capability of binding to it in their As- and Cd-binding conformational states, respectively. Water samples containing toxic metals were incubated on a complex of GFP-tagged ArsR or CadC and cis element which was immobilized on a solid surface. Metal concentrations were quantified with fluorescence intensity of the metal-binding states released from the cis element. Fluorescence intensity obtained with the assay significantly increased with increasing concentrations of toxic metals. Detection limits of 1 μg/L for Cd(II) and 5 μg/L for As(III) in purified water and 10 µg/L for Cd(II) and As(III) in tap water and bottled mineral water were achieved by measurement with a battery-powered portable fluorometer after 15-min and 30-min incubation, respectively. A complex of freeze dried GFP-tagged ArsR or CadC binding to cis element was stable at 4 °C and responded to 5 μg/L As(III) or Cd(II). The solid phase biosensors are sensitive, less time-consuming, portable, and could offer a protocol for on-site evaluation of the toxic metals in drinking water. PMID:22346629

  18. Metal-ligand redox reactions in gas-phase quaternary peptide-metal complexes by electrospray ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Vaisar, T.; Gatlin, C. L.; Turecek, F.

    1997-03-01

    The dipeptides Phe-Leu, Leu-Phe, Leu-Ala, and Ala-Leu form quaternary complexes of the type [Cu(II)(peptide - 2H+M)bpy]+ in the gas phase when electrosprayed in the presence of Cu(II) salts, 2.2'-bipyridyl (bpy), and an alkali hydroxide (MOH). The gas-phase complexes decarboxylate on collisional activation at low ion kinetic energies. The resulting ions undergo unusual eliminations of neutral Na, K, and Rb, which depend on the peptide structure. The ionization energy of the decarboxylated Phe-Leu-Cu-bpy complex was bracketed at 4.2 eV. Other collision-induced dissociations also depend on the alkali metal ion and the peptide structure. Ab initio calculations on a model system are reported and used to discuss the electronic properties of the peptide complexes.

  19. Multivariate multiscale complex network analysis of vertical upward oil-water two-phase flow in a small diameter pipe

    NASA Astrophysics Data System (ADS)

    Gao, Zhong-Ke; Yang, Yu-Xuan; Zhai, Lu-Sheng; Dang, Wei-Dong; Yu, Jia-Liang; Jin, Ning-De

    2016-02-01

    High water cut and low velocity vertical upward oil-water two-phase flow is a typical complex system with the features of multiscale, unstable and non-homogenous. We first measure local flow information by using distributed conductance sensor and then develop a multivariate multiscale complex network (MMCN) to reveal the dispersed oil-in-water local flow behavior. Specifically, we infer complex networks at different scales from multi-channel measurements for three typical vertical oil-in-water flow patterns. Then we characterize the generated multiscale complex networks in terms of network clustering measure. The results suggest that the clustering coefficient entropy from the MMCN not only allows indicating the oil-in-water flow pattern transition but also enables to probe the dynamical flow behavior governing the transitions of vertical oil-water two-phase flow.

  20. Multivariate multiscale complex network analysis of vertical upward oil-water two-phase flow in a small diameter pipe

    PubMed Central

    Gao, Zhong-Ke; Yang, Yu-Xuan; Zhai, Lu-Sheng; Dang, Wei-Dong; Yu, Jia-Liang; Jin, Ning-De

    2016-01-01

    High water cut and low velocity vertical upward oil-water two-phase flow is a typical complex system with the features of multiscale, unstable and non-homogenous. We first measure local flow information by using distributed conductance sensor and then develop a multivariate multiscale complex network (MMCN) to reveal the dispersed oil-in-water local flow behavior. Specifically, we infer complex networks at different scales from multi-channel measurements for three typical vertical oil-in-water flow patterns. Then we characterize the generated multiscale complex networks in terms of network clustering measure. The results suggest that the clustering coefficient entropy from the MMCN not only allows indicating the oil-in-water flow pattern transition but also enables to probe the dynamical flow behavior governing the transitions of vertical oil-water two-phase flow. PMID:26833427

  1. Multivariate multiscale complex network analysis of vertical upward oil-water two-phase flow in a small diameter pipe.

    PubMed

    Gao, Zhong-Ke; Yang, Yu-Xuan; Zhai, Lu-Sheng; Dang, Wei-Dong; Yu, Jia-Liang; Jin, Ning-De

    2016-01-01

    High water cut and low velocity vertical upward oil-water two-phase flow is a typical complex system with the features of multiscale, unstable and non-homogenous. We first measure local flow information by using distributed conductance sensor and then develop a multivariate multiscale complex network (MMCN) to reveal the dispersed oil-in-water local flow behavior. Specifically, we infer complex networks at different scales from multi-channel measurements for three typical vertical oil-in-water flow patterns. Then we characterize the generated multiscale complex networks in terms of network clustering measure. The results suggest that the clustering coefficient entropy from the MMCN not only allows indicating the oil-in-water flow pattern transition but also enables to probe the dynamical flow behavior governing the transitions of vertical oil-water two-phase flow. PMID:26833427

  2. Characterization of Horizontal Gas-Liquid Two-Phase Flow Using Markov Model-Based Complex Network

    NASA Astrophysics Data System (ADS)

    Hu, Li-Dan; Jin, Ning-De; Gao, Zhong-Ke

    2013-05-01

    Horizontal gas-liquid two-phase flow widely exists in many physical systems and chemical engineering processes. Compared with vertical upward gas-liquid two-phase flow, investigations on dynamic behavior underlying horizontal gas-liquid flows are quite limited. Complex network provides a powerful framework for time series analysis of complex dynamical systems. We use a network generation method based on Markov transition probability to infer directed weighted complex networks from signals measured from horizontal gas-liquid two-phase flow experiment and find that the networks corresponding to different flow patterns exhibit different network structure. To investigate the dynamic characteristics of horizontal gas-liquid flows, we construct a number of complex networks under different flow conditions, and explore the network indices for each constructed network. In addition, we investigate the sample entropy of different flow patterns. Our results suggest that the network statistic can well represent the complexity in the transition among different flow patterns and further allows characterizing the interface fluctuation behavior in horizontal gas-liquid two-phase flow.

  3. Identification of Guest-Host Inclusion Complexes in the Gas Phase by Electrospray Ionization-Mass Spectrometry

    ERIC Educational Resources Information Center

    Mendes, De´bora C.; Ramamurthy, Vaidhyanathan; Da Silva, Jose´ P.

    2015-01-01

    In this laboratory experiment, students follow a step-by-step procedure to prepare and study guest-host complexes in the gas phase using electrospray ionization-mass spectrometry (ESI-MS). Model systems are the complexes of hosts cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) with the guest 4-styrylpyridine (SP). Aqueous solutions of CB7 or CB8…

  4. Complex defect in pyrite and its structure model derived from geometric phase analysis.

    PubMed

    Németh, Péter; Dódony, István; Pósfai, Mihály; Buseck, Peter R

    2013-10-01

    New methods for defect analysis can lead to improved interpretation of experimental data and thus better understanding of material properties. Although transmission electronmicroscopy (TEM) has been used to study defects for many decades, interpretive ambiguities can arise for cases that seem simple or even trivial.Using geometric phase analysis (GPA), an image processing procedure, we show that an apparent simple line defect in pyrite has an entirely different character. It appears to be a b = ½[100] edge dislocation as viewed in a [001] high-resolution TEM (HRTEM) image, but the measured u(x) and u(y) displacements are asymmetric, which is inconsistent with a simple line dislocation. Instead, the defect is best understood as a terminating {101} marcasite slab in pyrite. The simulated HRTEM image based on this model reproduces the defect contrast and illustrates the power of GPA analysis for (1) avoiding potential pitfalls of misinterpreting apparently simple defects in HRTEM images, (2) detecting differences in elastic properties at the atomic scale, and (3) providing data for the positions of atom columns, thereby facilitating the construction of structure models for complex defects. PMID:23773546

  5. Supersaturation-limited and Unlimited Phase Transitions Compete to Produce the Pathway Complexity in Amyloid Fibrillation.

    PubMed

    Adachi, Masayuki; So, Masatomo; Sakurai, Kazumasa; Kardos, József; Goto, Yuji

    2015-07-17

    Although amyloid fibrils and amorphous aggregates are two types of aggregates formed by denatured proteins, their relationship currently remains unclear. We used β2-microglobulin (β2m), a protein responsible for dialysis-related amyloidosis, to clarify the mechanism by which proteins form either amyloid fibrils or amorphous aggregates. When ultrasonication was used to accelerate the spontaneous fibrillation of β2m at pH 2.0, the effects observed depended on ultrasonic power; although stronger ultrasonic power effectively accelerated fibrillation, excessively strong ultrasonic power decreased the amount of fibrils formed, as monitored by thioflavin T fluorescence. An analysis of the products formed indicated that excessively strong ultrasonic power generated fibrillar aggregates that retained β-structures but without high efficiency as seeds. On the other hand, when the spontaneous fibrillation of β2m was induced at higher concentrations of NaCl at pH 2.0 with stirring, amorphous aggregates became more dominant than amyloid fibrils. These apparent complexities in fibrillation were explained comprehensively by a competitive mechanism in which supersaturation-limited reactions competed with supersaturation-unlimited reactions. We link the kinetics of protein aggregation and a conformational phase diagram, in which supersaturation played important roles. PMID:26063798

  6. POD evaluation using simulation: A phased array UT case on a complex geometry part

    NASA Astrophysics Data System (ADS)

    Dominguez, Nicolas; Reverdy, Frederic; Jenson, Frederic

    2014-02-01

    The use of Probability of Detection (POD) for NDT performances demonstration is a key link in products lifecycle management. The POD approach is to apply the given NDT procedure on a series of known flaws to estimate the probability to detect with respect to the flaw size. A POD is relevant if and only if NDT operations are carried out within the range of variability authorized by the procedure. Such experimental campaigns require collection of large enough datasets to cover the range of variability with sufficient occurrences to build a reliable POD statistics, leading to expensive costs to get POD curves. In the last decade research activities have been led in the USA with the MAPOD group and later in Europe with the SISTAE and PICASSO projects based on the idea to use models and simulation tools to feed POD estimations. This paper proposes an example of application of POD using simulation on the inspection procedure of a complex -full 3D- geometry part using phased arrays ultrasonic testing. It illustrates the methodology and the associated tools developed in the CIVA software. The paper finally provides elements of further progress in the domain.

  7. Investigation of the kinetic process of solid phase microextraction in complex sample.

    PubMed

    Jiang, Ruifen; Xu, Jianqiao; Lin, Wei; Wen, Sijia; Zhu, Fang; Luan, Tiangang; Ouyang, Gangfeng

    2015-11-01

    The presence of complex matrix in the aquatic system affects the environmental behavior of hydrophobic organic compounds (HOCs). In the current study, an automated solid-phase microextraction (SPME) desorption method was employed to study the effect of 2-hydroxypropyl-β-cyclodextrin (β-HPCD) on the kinetic process of 5 selected polyaromatic hydrocarbons (PAHs) desorbing from the fiber in aqueous sample. The results showed that the added β-HPCD facilitated the desorption rates of PAHs from SPME fiber coating, and the enhancement effect can be predicted by a proposed theoretical model. Based on this model, the kinetic parameters of organic compounds desorbing from the SPME fiber can be determined, and the calculated results showed good agreement with the experimental data. In addition, the effect of temperature on the desorption kinetic was investigated. The results found that the SPME desorption time constant increased as the sampling temperature elevated, and followed the Arrhenius equation. Also, the temperature facilitated the desorption of HOCs from the bound matrix so that increased the lability degrees of the bound compounds. Finally, a calibration method based on the proposed theoretical model was developed and applied for the analysis of unknown sample. PMID:26572846

  8. Hydration of gas-phase ytterbium ion complexes studied by experiment and theory

    SciTech Connect

    Rutkowski, Philip X; Michelini, Maria C.; Bray, Travis H.; Russo, Nino; Marcalo, Joaquim; Gibson, John K.

    2011-02-11

    Hydration of ytterbium (III) halide/hydroxide ions produced by electrospray ionization was studied in a quadrupole ion trap mass spectrometer and by density functional theory (DFT). Gas-phase YbX{sub 2}{sup +} and YbX(OH){sup +} (X = OH, Cl, Br, or I) were found to coordinate from one to four water molecules, depending on the ion residence time in the trap. From the time dependence of the hydration steps, relative reaction rates were obtained. It was determined that the second hydration was faster than both the first and third hydrations, and the fourth hydration was the slowest; this ordering reflects a combination of insufficient degrees of freedom for cooling the hot monohydrate ion and decreasing binding energies with increasing hydration number. Hydration energetics and hydrate structures were computed using two approaches of DFT. The relativistic scalar ZORA approach was used with the PBE functional and all-electron TZ2P basis sets; the B3LYP functional was used with the Stuttgart relativistic small-core ANO/ECP basis sets. The parallel experimental and computational results illuminate fundamental aspects of hydration of f-element ion complexes. The experimental observations - kinetics and extent of hydration - are discussed in relationship to the computed structures and energetics of the hydrates. The absence of pentahydrates is in accord with the DFT results, which indicate that the lowest energy structures have the fifth water molecule in the second shell.

  9. Hydrogen-bonded glycine-HCN complexes in gas phase: structure, energetics, electric properties and cooperativity

    NASA Astrophysics Data System (ADS)

    Machado da Silva, Arnaldo; Chakrabarty, Sumana; Chaudhuri, Puspitapallab

    2015-03-01

    Twelve hydrogen-bonded complexes of glycine and hydrogen cyanide have been studied using high-level quantum-chemical calculations in gas phase. In particular, six 1:1 glycine-HCN dimers and six 1:2 glycine-HCN trimers have been considered. Besides the characteristics of the hydrogen bonds and their effect on molecular structure and energetics, several molecular electric properties have been calculated utilising two different models: MP2/6-31++G(d,p) and DFT-B3LYP/6-31++G(d,p). Although the structural parameters calculated by the two models are similar, equilibrium electronic energies of the clusters show model dependence. The lowest energy dimer is same in both the models which is ca. 3.0 kcal/mol more stable than the highest energy dimer. However, the lowest energy trimer is different in two methods. The energetic difference of stability between the highest and lowest trimer is 4.2 kcal/mol (4.4 kcal/mol) at an MP2 (B3LYP) level of calculation. The bond angles of glycine, in particular, are quite sensitive to the hydrogen-bond formation. Four out of six trimers are found to be strongly cooperative in both the models. Significant changes of dipole moments and polarisabilities of isolated glycine and hydrogen cyanide are observed due to the formation of hydrogen bonding. The Rayleigh scattering intensities of all clusters are much larger than those of their constituent monomers.

  10. Implementation of a complex multi-phase equation of state for cerium and its correlation with experiment

    SciTech Connect

    Cherne, Frank J; Jensen, Brian J; Elkin, Vyacheslav M

    2009-01-01

    The complexity of cerium combined with its interesting material properties makes it a desirable material to examine dynamically. Characteristics such as the softening of the material before the phase change, low pressure solid-solid phase change, predicted low pressure melt boundary, and the solid-solid critical point add complexity to the construction of its equation of state. Currently, we are incorporating a feedback loop between a theoretical understanding of the material and an experimental understanding. Using a model equation of state for cerium we compare calculated wave profiles with experimental wave profiles for a number of front surface impact (cerium impacting a plated window) experiments. Using the calculated release isentrope we predict the temperature of the observed rarefaction shock. These experiments showed that the release state occurs at different magnitudes, thus allowing us to infer where dynamic {gamma} - {alpha} phase boundary is.

  11. The relationship between microstructure and damage evolution in hot-rolled complex-phase steel sheet

    NASA Astrophysics Data System (ADS)

    Bell, Grant A. S.

    Complex-phase (CP) steels are employed in applications that require high-strength and good edge formability. These steels derive their strength from a fine-grained bainite-ferrite microstructure, and alloying to provide solid-solution and precipitation strengthening. CP steels are produced industrially through a process of controlled rolling and cooling to produce desirable microstructures. Hole-expansion tests are typically used as a measure of edge formability for applications such as stretch-flanges. It has been shown that CP microstructures are susceptible to large fluctuations in hole-expansion performance with little change in processing or resulting tensile properties. The steel's characteristics of damage evolution are critical to the hole-expansion performance. This study investigates the role of microstructure in the development of damage in CP microstructural variants. Two variant pairs of different thicknesses were produced from the leading and trailing edge of industrially produced hot-rolled sheet. Each pair consisted of a variant with poor hole-expansion performance, and a variant with good hole-expansion performance. Each variant was tested via interrupted double-notched uniaxial tension testing to induce damage. Damage evolution in each variant was quantified by X-ray micro-computed tomography (XmicroCT), and supplementary optical micrography. The damage results were correlated with microstructural characteristics. It was shown that poor hole-expansion variants failed by intergranular fracture. In these variants, void damage induced by hard martensite and retained austenite was not critical in producing failure. Purely void-damaged microstructures failed by ductile fracture, whereas cracked microstructures failed in a mixed brittle-ductile failure initiated by planar cracks. Microstructural banding of large elongated ferrite grains correlated with the existence of intergranular planar fractures.

  12. Pseudotachylyte in the Tananao Metamorphic Complex, Taiwan: Occurrence and dynamic phase changes of fossil earthquakes

    NASA Astrophysics Data System (ADS)

    Chu, Hao-Tsu; Hwang, Shyh-Lung; Shen, Pouyan; Yui, Tzen-Fu

    2012-12-01

    Pseudotachylyte veins and cataclasites were studied in the mylonitized granitic gneiss of the Tananao Metamorphic Complex at Hoping, Eastern Taiwan. The aphanitic pseudotachylyte veins vary in thickness, ranging from millimeters to about 1 cm. Field and optical microscopic observations show that such pseudotachylyte veins cut across cataclasites, which, in turn, transect the mylonitized granitic gneiss. Scanning electron microscopic images also show that both the pseudotachylyte veins and the cataclasites have been metasomatized by a K-rich fluid, resulting in the replacement of Na-plagioclase by K-feldspar (veins). Analytical electron microscopic observations reveal further details of physical and chemical changes (mainly fragmentation, dislocations, cleaving-healing with inclusions and relic voids, and retention of high-temperature albite) of quartz and feldspar in crushed grains. Pseudotachylytes occur as dark veins having a higher content of chlorite-biotite, clinozoisite-epidote and titanite fragments than cataclasites. These veins, coupled with hematite/jarosite-Fe-rich amorphous shell/carbonaceous material, indicate that crushing, healing/sintering, and inhomogeneous melt/fluid infiltration involving incipient and intermediate/high temperature melt patches, before and/or contemporaneous with the metasomatic K-rich fluid, prevailed in a coupled or sequential manner in the faulting event to form nonequilibrium phase assemblage. The chlorite-biotite, carbonaceous material and other nanoscale minerals could be vulnerable in future earthquakes under the influence of water. The timing of the formation of these pseudotachylyte veins should be later than the area's age of mylonitization of granitic gneiss of approximately 4.1-3.0 Ma (Wang et al., 1998). The formation of pseudotachylytes registers the fossil earthquakes during early stages in the exhumation history of the uplifting Taiwan Mountain belt since the Plio-Pleistocene Arc-Continent collision.

  13. Symptom Complexes at the Earliest Phases of Rheumatoid Arthritis: A Synthesis of the Qualitative Literature

    PubMed Central

    Stack, Rebecca J; Sahni, Melanie; Mallen, Christian D; Raza, Karim

    2013-01-01

    Objective Understanding the features and patterns of symptoms that characterize the earliest stages of rheumatoid arthritis (RA) is of considerable importance if patients are to be identified and started on treatment early. However, little is known about the characteristics of symptoms at the onset of a disease that eventually progresses to RA. Methods A systematic review of qualitative peer-reviewed publications was conducted to identify the earliest symptoms associated with the onset of RA. A total of 1,736 abstracts were searched to identify relevant publications. Twenty-six publications were identified, assessed for quality, and subjected to analysis informed by thematic and grounded theory frameworks. Results Several interacting themes describing the early symptoms of RA were identified, including swelling, pain and tenderness, stiffness, fatigue and weakness, and the emotional impact of symptoms. For each symptom, different and evolving intensities were described; in some cases, patterns of symptom onset and symptom complexes at the onset of RA were highlighted. Importantly, this review has emphasized major deficiencies in the literature. None of the studies reviewed originally aimed to explore symptoms at RA onset (often discussions about symptom onset were secondary to the study's primary aim). Also, many of the articles identified sampled people diagnosed with RA many years previously, making their recollection of symptoms at onset less reliable. Conclusion In order for clinicians to fully understand the earliest phases of disease, the nature of symptoms at onset needs to be understood. The current work represents a useful starting point, but this area needs further qualitative investigation, followed by quantitative explorations of symptom clusters and their associated features. PMID:23926091

  14. Duality in Phase Space and Complex Dynamics of an Integrated Pest Management Network Model

    NASA Astrophysics Data System (ADS)

    Yuan, Baoyin; Tang, Sanyi; Cheke, Robert A.

    Fragmented habitat patches between which plants and animals can disperse can be modeled as networks with varying degrees of connectivity. A predator-prey model with network structures is proposed for integrated pest management (IPM) with impulsive control actions. The model was analyzed using numerical methods to investigate how factors such as the impulsive period, the releasing constant of natural enemies and the mode of connections between the patches affect pest outbreak patterns and the success or failure of pest control. The concept of the cluster as defined by Holland and Hastings is used to describe variations in results ranging from global synchrony when all patches have identical fluctuations to n-cluster solutions with all patches having different dynamics. Heterogeneity in the initial densities of either pest or natural enemy generally resulted in a variety of cluster oscillations. Surprisingly, if n > 1, the clusters fall into two groups one with low amplitude fluctuations and the other with high amplitude fluctuations (i.e. duality in phase space), implying that control actions radically alter the system's characteristics by inducing duality and more complex dynamics. When the impulsive period is small enough, i.e. the control strategy is undertaken frequently, the pest can be eradicated. As the period increases, the pest's dynamics shift from a steady state to become chaotic with periodic windows and more multicluster oscillations arise for heterogenous initial density distributions. Period-doubling bifurcation and periodic halving cascades occur as the releasing constant of the natural enemy increases. For the same ecological system with five differently connected networks, as the randomness of the connectedness increases, the transient duration becomes smaller and the probability of multicluster oscillations appearing becomes higher.

  15. Poly-phase Deformation Recorded in the Core of the Coast Plutonic Complex, Western British Columbia

    NASA Astrophysics Data System (ADS)

    Hamblock, J. M.; Andronicos, C. L.; Hurtado, J. M.

    2006-05-01

    of orthogneiss was concurrent with S2 deformation of the amphibolite gneiss. Tectonic strains calculated by the Rf-φ method using mafic enclaves in the orthogneiss vary from 4 to 10 within an area <1 km2, suggesting strong strain gradients during D2. S3 foliations strike WNW-ESE to E-W and dip shallowly to the south, suggesting NNE-SSW to N-S shortening. L3 lineations plunge shallowly to the SW and SE, and are associated low-angle shear bands with greenschist facies mineral assemblages which overprint higher temperature assemblages. Deformation phase D4 is characterized by low temperature, brittle deformation as shown by discrete fault surfaces with abundant chlorite. The following tectonic history can be determined based on structural observations. Amphibolite and immature sedimentary material formed from supracrustal (e.g. basalt flows?) and intrusive protoliths. These units were then intruded by the gabbro- diorite, which was deformed by right and left lateral shear zones sometime after crystallization. Both the amphibolite and gabbro-diorite were intruded by the orthogneiss, which was emplaced as sills during right and left lateral shearing and F2 folding. This geologic history is similar to that preserved in other parts of the Coast Plutonic Complex where dextral transpression and sinistral transtension are documented. The localization of low angle normal shear zones with greenschist facies mineral assemblages suggests extension occurred during cooling of the arc.

  16. Insoluble Fe-humic acid complex as a solid-phase electron mediator for microbial reductive dechlorination.

    PubMed

    Zhang, Chunfang; Zhang, Dongdong; Li, Zhiling; Akatsuka, Tetsuji; Yang, Suyin; Suzuki, Daisuke; Katayama, Arata

    2014-06-01

    We report that the insoluble Fe-HA complex, which was synthesized with both commercial Aldrich humic acid (HA) and natural HA, functions as a solid-phase electron mediator (EM) for the anaerobic microbial dechlorination of pentachlorophenol. Spectroscopic characterizations and sequential Fe extraction demonstrated that the Fe-HA complex was predominated with Na4P2O7-labile Fe (represented as the organically bound Fe fraction) and poorly ordered Fe fraction (the fraction left in the residue after the sequential extraction), which were associated with different possible binding processes with carboxylate and phenolic groups. The change in the electron-mediating activity caused by Fe extraction indicated that the electron-mediating function of the Fe-HA complex is attributable to the Na4P2O7-labile Fe fraction. The Fe-HA complex also accelerated the microbial reduction of Fe(III) oxide, which suggested the presence of multiple electron-mediating functions in the complex. The electron shuttle assay showed that the Fe-HA complex had an electron-accepting capacity of 0.82 mequiv g(-1) dry Fe-HA complex. The presence of redox-active moieties in the Fe-HA complex was verified by cyclic voltammetry analysis of the sample after electrical reduction, with a redox potential estimated at 0.02 V (vs a standard hydrogen electrode). PMID:24758743

  17. Low-complexity optical phase noise suppression in CO-OFDM system using recursive principal components elimination.

    PubMed

    Hong, Xiaojian; Hong, Xuezhi; He, Sailing

    2015-09-01

    A low-complexity optical phase noise suppression approach based on recursive principal components elimination, R-PCE, is proposed and theoretically derived for CO-OFDM systems. Through frequency domain principal components estimation and elimination, signal distortion caused by optical phase noise is mitigated by R-PCE. Since matrix inversion and domain transformation are completely avoided, compared with the case of the orthogonal basis expansion algorithm (L = 3) that offers a similar laser linewidth tolerance, the computational complexities of multiple principal components estimation are drastically reduced in the R-PCE by factors of about 7 and 5 for q = 3 and 4, respectively. The feasibility of optical phase noise suppression with the R-PCE and its decision-aided version (DA-R-PCE) in the QPSK/16QAM CO-OFDM system are demonstrated by Monte-Carlo simulations, which verify that R-PCE with only a few number of principal components q ( = 3) provides a significantly larger laser linewidth tolerance than conventional algorithms, including the common phase error compensation algorithm and linear interpolation algorithm. Numerical results show that the optimal performance of R-PCE and DA-R-PCE can be achieved with a moderate q, which is beneficial for low-complexity hardware implementation. PMID:26368499

  18. High-Resolution Solid-State NMR Investigation of the Phase Transition in Decamethylferrocene-Acenaphthenequinone Charge-Transfer Complex

    NASA Astrophysics Data System (ADS)

    Nakamura, Hideaki; Kuwahara, Daisuke; Mochida, Tomoyuki

    2009-10-01

    A charge-transfer complex composed of decamethylferrocene (D) and acenaphthenequinone (A) was prepared. The material was a 1:1 neutral complex with a mixed-stack structure and exhibited a phase transition at -16 °C. High-resolution 13C and 1H NMR spectroscopy revealed that an inclination of A with respect to D occurs below the phase-transition temperature. The 1H spin-diffusion rates of the complex undergoing high-speed magic-angle spinning (MAS) were measured to determine the shortest 1H-1H distance r between D and A. To analyze the experimental results, we derived the analytical expression of the spin-diffusion rate Wz for a homonuclear multispin system undergoing MAS. It was found that Wz for the complex is proportional only to 1/r6 under high-speed MAS conditions. On the basis of this relationship and the crystal structure at 20 °C, it was determined that the shortest 1H-1H distance r at -27.7 °C (below the phase transition temperature) is 0.4 Å shorter than that at 20 °C. Given this information, a plausible model of the low-temperature structure is discussed.

  19. Controlling the phase structures of polymer/surfactant complexes by changing macromolecular architecture and adding n-alcohols.

    PubMed

    Percebom, Ana Maria; Loh, Watson

    2016-03-15

    Phase behavior of complex salts formed by a cationic surfactant and different ethoxylated polyions was investigated in water and with addition of two n-alcohols of different chain lengths: n-butanol and n-decanol. The polyion possesses a main chain of methacrylic acid randomly grafted with oligo(ethylene oxide) chains. Strong electrostatic interaction between the anionic main chain and the cationic surfactant hexadecyltrimethylammonium (C16TA) leads to the formation of C16TAP(MA-MAEO(n)) x:y complex salts. Modifications in polyion structure, such as changes in the proportion of grafted comonomers and in the side chain length caused differences in the overall balance of interactions with water and n-alcohols, altering the complex salt solubility and, consequently, the formed liquid-crystalline structures. The role of n-decanol as a cosurfactant was verified, but the hydrophilic side chains expanded the capacity of the formed liquid crystalline phases to incorporate water. Additionally, a novel structure, probably cubic bicontinuous (Pn3m), was observed coexisting with lamellar phases at low water concentration. Because n-butanol is known for being a good solvent for poly(ethylene oxide), these side chains intensified the role of this short chain n-alcohol as cosolvent for C16TAP(MA-MAEO(n)) x:y complex salts, favoring the formation of disordered solutions, including a bicontinuous microemulsion. PMID:26752433

  20. A 4-D dataset for validation of crystal growth in a complex three-phase material, ice cream

    NASA Astrophysics Data System (ADS)

    Rockett, P.; Karagadde, S.; Guo, E.; Bent, J.; Hazekamp, J.; Kingsley, M.; Vila-Comamala, J.; Lee, P. D.

    2015-06-01

    Four dimensional (4D, or 3D plus time) X-ray tomographic imaging of phase changes in materials is quickly becoming an accepted tool for quantifying the development of microstructures to both inform and validate models. However, most of the systems studied have been relatively simple binary compositions with only two phases. In this study we present a quantitative dataset of the phase evolution in a complex three-phase material, ice cream. The microstructure of ice cream is an important parameter in terms of sensorial perception, and therefore quantification and modelling of the evolution of the microstructure with time and temperature is key to understanding its fabrication and storage. The microstructure consists of three phases, air cells, ice crystals, and unfrozen matrix. We perform in situ synchrotron X-ray imaging of ice cream samples using in-line phase contrast tomography, housed within a purpose built cold-stage (-40 to +20oC) with finely controlled variation in specimen temperature. The size and distribution of ice crystals and air cells during programmed temperature cycling are determined using 3D quantification. The microstructural evolution of three-phase materials has many other important applications ranging from biological to structural and functional material, hence this dataset can act as a validation case for numerical investigations on faceted and non-faceted crystal growth in a range of materials.

  1. Oxidation of 2-propanol ligands during collision-induced dissociation of a gas-phase uranyl complex

    NASA Astrophysics Data System (ADS)

    van Stipdonk, Michael J.; Chien, Winnie; Anbalagan, Victor; Gresham, Garold L.; Groenewold, Gary S.

    2004-10-01

    We demonstrate, by way of multi-stage tandem mass spectrometry and extensive deuterium labeling, that 2-propanol is converted to acetone, and 2-propoxide to acetaldehyde, when monopositive 2-propanol-coordinated uranyl-ligand cations are subjected to collision-induced dissociation in the gas-phase environment of an ion trap mass spectrometer. A species with formula [(UO2OCH(CH3)2)(HOCH(CH3)2)]+, derived from dissociation of the gas-phase precursor [(UO2NO3)(HOCH(CH3)2)3]+ eliminates two H atoms and CH3 in consecutive stages to generate a monopositive complex composed of the U(V) species UO2+ coordinated by acetone and acetaldehyde, i.e. [UO2+(OC(CH3)2)(OC(H)CH3)]. Dissociation of this latter ion resulted in elimination of the two coordinating carbonyl ligands in two consecutive dissociation stages to leave UO2+. Analogous reactions were not observed for uranyl complexes containing 1-propanol or 2-methyl-2-propanol, or for cationic complexes with divalent metals such as Ni2+, Co2+, Pb2+ and Ca2+. One explanation for these reactions is bond insertion by the metal center in the bis-ligated uranyl complex, which would be expected to have an LUMO consisting of unoccupied 6d-orbitals that would confer transition metal-like behavior on the complex.

  2. Gas-phase coordination complexes of dipositive plutonyl, PuO2(2+): chemical diversity across the actinyl series.

    PubMed

    Rios, Daniel; Rutkowski, Philip X; Van Stipdonk, Michael J; Gibson, John K

    2011-06-01

    We report the first transmission of solvent-coordinated dipositive plutonyl ion, Pu(VI)O(2)(2+), from solution to the gas phase by electrospray ionization (ESI) of plutonyl solutions in water/acetone and water/acetonitrile. ESI of plutonyl and uranyl solutions produced the isolable gas-phase complexes, [An(VI)O(2)(CH(3)COCH(3))(4,5,6)](2+), [An(VI)O(2)(CH(3)COCH(3))(3)(H(2)O)](2+), and [An(VI)O(2)(CH(3)CN)(4)](2+); additional complex compositions were observed for uranyl. In accord with relative actinyl stabilities, U(VI)O(2)(2+) > Pu(VI)O(2)(2+) > Np(VI)O(2)(2+), the yields of plutonyl complexes were about an order of magnitude less than those of uranyl, and dipositive neptunyl complexes were not observed. Collision-induced dissociation (CID) of the dipositive coordination complexes in a quadrupole ion trap produced doubly- and singly-charged fragment ions; the fragmentation products reveal differences in underlying chemistries of plutonyl and uranyl, including the lower stability of Pu(VI) as compared with U(VI). Particularly notable was the distinctive CID fragment ion, [Pu(IV)(OH)(3)](+) from [Pu(VI)O(2)(CH(3)COCH(3))(6)](2+), where the plutonyl structure has been disrupted and the tetravalent plutonium hydroxide produced; this process was not observed for uranyl. PMID:21517017

  3. Divalent and trivalent gas-phase coordination complexes of californium: evaluating the stability of Cf(ii).

    PubMed

    Dau, Phuong D; Shuh, David K; Sturzbecher-Hoehne, Manuel; Abergel, Rebecca J; Gibson, John K

    2016-08-01

    The divalent oxidation state is increasingly stable relative to the trivalent state for the later actinide elements, with californium the first actinide to exhibit divalent chemistry under moderate conditions. Although there is evidence for divalent Cf in solution and solid compounds, there are no reports of discrete complexes in which Cf(II) is coordinated by anionic ligands. Described here is the divalent Cf methanesulfinate coordination complex, Cf(II)(CH3SO2)3(-), prepared in the gas phase by reductive elimination of CH3SO2 from Cf(III)(CH3SO2)4(-). Comparison with synthesis of the corresponding Sm and Cm complexes reveals reduction of Cf(III) and Sm(III), and no evidence for reduction of Cm(III). This reflects the comparative 3+/2+ reduction potentials: Cf(3+) (-1.60 V) ≈ Sm(3+) (-1.55 V) ≫ Cm(3+) (-3.7 V). Association of O2 to the divalent complexes is attributed to formation of superoxides, with recovery of the trivalent oxidation state. The new gas-phase chemistry of californium, now the heaviest element to have been studied in this manner, provides evidence for Cf(II) coordination complexes and similar chemistry of Cf and Sm. PMID:27424652

  4. Phase behavior and structure of stable complexes between a long polyanion and a branched polycation

    NASA Astrophysics Data System (ADS)

    Mengarelli, Valentina; Zeghal, Mehdi; Auvray, Loïc; Clemens, Daniel

    2011-08-01

    The association between oppositely charged branched polyethylenimine (BPEI) and polymethacrylic acid (PMA) in the dilute regime is investigated using turbidimetric titration and electrophoretic mobility measurements. The complexation is controlled by tuning continuously the pH-sensitive charge of the polyacid in acidic solution. The formation of soluble and stable positively charged complexes is a cooperative process characterized by the existence of two regimes of weak and strong complexation. In the regime of weak complexation, a long PMA chain overcharged by several BPEI molecules forms a binary complex. As the charge of the polyacid increases, these binary complexes condense at a well defined charge ratio of the mixture to form large positively charged aggregates. The overcharging and the existence of two regimes of complexation are analyzed in the light of recent theories. The structure of the polyelectrolytes is investigated at higher polymer concentration by small angle neutron scattering. Binary complexes of finite size present an open structure where the polyacid chains connecting a small number of BPEI molecules have shrunk slightly. In the condensed complexes, BPEI molecules, wrapped by polyacid chains, form networks of stretched necklaces.

  5. Passage of TBP-uranyl complexes from aqueous-organic interface to the organic phase: insights from molecular dynamics simulation.

    PubMed

    Sahu, Pooja; Ali, Sk Musharaf; Shenoy, Kalasanka Trivikram

    2016-08-24

    The present study reports molecular dynamics simulations for biphasic systems comprising tributyl phosphate (TBP) in dodecane and uranyl nitrate in the aqueous phase, which are key chemical species in the well-known Pu-U extraction (PUREX) process. An attempt has been made to understand the nature of interface and mechanism of 'TBP associated uranyl' crossing under neutral and acidic conditions. Results show that the solvent density undergoes large fluctuation near the interface depending on the nature of the aqueous-organic phase. The study provides compelling evidence of experimentally observed reorganization of interfacial complexes at the interface and their structural reformation during extraction. It has been observed that the surface active nature of TBP and their interfacial coverage is modulated by the nature of incorporated solute species and their location with respect to the interface. Also, the TBP structuring near the interface is destroyed when an acidic interface is considered rather than a neutral one which favors the uranyl extraction. With an acidic interface, the water humidity of organic phase was observed to be increased in the experiments. Furthermore, the acid/water solubility in the organic phase was observed to be influenced by selection of acid models and their concentration. Simulations with high acid concentration show water pocket formation in the organic phase. However, in the case of dissociated ions or a mixture of both, no such water pool is observed and the extracted water remains dispersed in the organic phase, having the tendency to be replaced by HNO3 because of preferred TBP·HNO3 complexation over TBP·H2O. Most remarkably, the present study makes evident the TBP-induced charge redistribution of uranyl complexes during migration from the interface to the bulk organic phase, which contributes to drive uranyl complexes such as UO2·NO3·4TBP, UO2·5TBP and UO2·NO3·3TBP·HNO3 in the organic phase, and this was reestablished by

  6. New chelating reagents for preconcentration, separation, determination of metal complexes by high performance liquid chromatography and solid phase extraction

    SciTech Connect

    Qian, Yan wen.

    1991-12-03

    A general scheme is outlined for rapid determination of metal cations by complexation and subsequent HPLC separation. The synthesis and general properties are described for several new thiohydrazone chelating reagents. Solubility considerations suggest that the metal complexes have a positive charge. Excellent chromatographic separations are obtained for mixtures of up to seven metal complexes. Addition of a positively charged additive to the eluent is shown to have a significant effect on both the retention times and sharpness of the chromatographic peaks. Separation of the metal complexes on resins with a permanent charge is also shown to be feasible. Two new hydrazone reagents have been synthesized and characterized. Trace metal ions in aqueous solution are complexed by one of the hydrazones and the resulting metal complexes are solid phase extracted onto a mini cation-exchange or polymeric column. The uptake of metal complexes is complete and the elution step is fast and complete. The quantitative recoveries of metal ions determined by both spectrophotometric method and ICP-MS are very satisfactory and agree with each other.

  7. Spectroscopic Characterization and Reactivity of Triplet and Quintet Iron(IV) Oxo Complexes in the Gas Phase

    PubMed Central

    Andris, Erik; Jašík, Juraj; Gómez, Laura

    2016-01-01

    Abstract Closely structurally related triplet and quintet iron(IV) oxo complexes with a tetradentate aminopyridine ligand were generated in the gas phase, spectroscopically characterized, and their reactivities in hydrogen‐transfer and oxygen‐transfer reactions were compared. The spin states were unambiguously assigned based on helium tagging infrared photodissociation (IRPD) spectra of the mass‐selected iron complexes. It is shown that the stretching vibrations of the nitrate counterion can be used as a spectral marker of the central iron spin state. PMID:26878833

  8. The Nonlinear Phase Response Curve of the Human Circadian Pacemaker and How Complex Behaviors Might Arise in Nature

    NASA Astrophysics Data System (ADS)

    Leder, Ron S.

    2002-08-01

    Our example from nature is two groups of about 10,000 cells in the brain called Suprachiasmatic Nuclei (SCN) and how light can entrain free running endogenous periodic behavior via the retina's connection to the SCN. Our major question is how a complex behavior like this can arise in nature. Finally presented is a mathematical model and simulation showing how simple periodic signals can be coupled to produce spatio-temporal chaotic behavior and how two complex signals can combine to produce simple coherent behavior with a hypothetical analogy to phase resetting in biological circadian pacemakers.

  9. Rotational Analysis of Phase Plane Curves: Complex and Pure Imaginary Eigenvalues

    ERIC Educational Resources Information Center

    Murray, Russell H.

    2005-01-01

    Although the phase plane can be plotted and analyzed using an appropriate software package, the author found it worthwhile to engage the students with the theorem and the two proofs. The theorem is a powerful tool that provides insight into the rotational behavior of the phase plane diagram in a simple way: just check the signs of c and [alpha].…

  10. Time-domain Vander-Lugt filters for in-fiber complex (amplitude and phase) optical pulse shaping.

    PubMed

    Fernández-Ruiz, María R; Huh, Jeonghyun; Azaña, José

    2016-05-01

    The time-domain counterpart of spatial Vander-Lugt filters is proposed for the first time, to the best of our knowledge. The concept enables reshaping an ultrashort optical pulse into a desired complex (amplitude and phase) arbitrary temporal pulse waveform using a setup configuration similar to that of previously demonstrated fiber-optic time-domain pulse-intensity shapers, i.e., using a single temporal amplitude modulator between two opposite-dispersive all-fiber media. The proposal is experimentally validated through reconfigurable generation of two complex-valued pulse shapes, namely, a 60 ps asymmetrical triangular pulse with controlled parabolic phase and a 4-symbol 16-QAM picosecond pulse code sequence. PMID:27128089

  11. Compression of ultra-long microwave pulses using programmable microwave photonic phase filtering with > 100 complex-coefficient taps.

    PubMed

    Song, Minhyup; Torres-Company, Victor; Wu, Rui; Metcalf, Andrew J; Weiner, Andrew M

    2014-03-24

    Microwave photonic filters with arbitrary phase response can be achieved by merging high-repetition-rate electro-optic frequency comb technology with line-by-line pulse shaping. When arranged in an interferometric configuration, the filter features a number of programmable complex-coefficient taps equal to the number of available comb lines. In this work, we use an ultrabroadband comb generator resulting in a microwave photonic phase filter with >100 complex-coefficient taps. We demonstrate the potential of this filter by performing programmable chirp control of ultrawideband waveforms that extend over long (>10 ns) temporal apertures. This work opens new possibilities for compensating realistic linear distortion impairments on ultrabroadband wireless signals spanning over dozens of nanosecond temporal apertures. PMID:24663981

  12. Efficient Covalent Bond Formation in Gas-Phase Peptide-Peptide Ion Complexes with the Photoleucine Stapler

    NASA Astrophysics Data System (ADS)

    Shaffer, Christopher J.; Andrikopoulos, Prokopis C.; Řezáč, Jan; Rulíšek, Lubomír; Tureček, František

    2016-04-01

    Noncovalent complexes of hydrophobic peptides GLLLG and GLLLK with photoleucine (L*) tagged peptides G(L* n L m )K (n = 1,3, m = 2,0) were generated as singly charged ions in the gas phase and probed by photodissociation at 355 nm. Carbene intermediates produced by photodissociative loss of N2 from the L* diazirine rings underwent insertion into X-H bonds of the target peptide moiety, forming covalent adducts with yields reaching 30%. Gas-phase sequencing of the covalent adducts revealed preferred bond formation at the C-terminal residue of the target peptide. Site-selective carbene insertion was achieved by placing the L* residue in different positions along the photopeptide chain, and the residues in the target peptide undergoing carbene insertion were identified by gas-phase ion sequencing that was aided by specific 13C labeling. Density functional theory calculations indicated that noncovalent binding to GL*L*L*K resulted in substantial changes of the (GLLLK + H)+ ground state conformation. The peptide moieties in [GL*L*LK + GLLLK + H]+ ion complexes were held together by hydrogen bonds, whereas dispersion interactions of the nonpolar groups were only secondary in ground-state 0 K structures. Born-Oppenheimer molecular dynamics for 100 ps trajectories of several different conformers at the 310 K laboratory temperature showed that noncovalent complexes developed multiple, residue-specific contacts between the diazirine carbons and GLLLK residues. The calculations pointed to the substantial fluidity of the nonpolar side chains in the complexes. Diazirine photochemistry in combination with Born-Oppenheimer molecular dynamics is a promising tool for investigations of peptide-peptide ion interactions in the gas phase.

  13. Efficient Covalent Bond Formation in Gas-Phase Peptide-Peptide Ion Complexes with the Photoleucine Stapler.

    PubMed

    Shaffer, Christopher J; Andrikopoulos, Prokopis C; Řezáč, Jan; Rulíšek, Lubomír; Tureček, František

    2016-04-01

    Noncovalent complexes of hydrophobic peptides GLLLG and GLLLK with photoleucine (L*) tagged peptides G(L* n L m )K (n = 1,3, m = 2,0) were generated as singly charged ions in the gas phase and probed by photodissociation at 355 nm. Carbene intermediates produced by photodissociative loss of N2 from the L* diazirine rings underwent insertion into X-H bonds of the target peptide moiety, forming covalent adducts with yields reaching 30%. Gas-phase sequencing of the covalent adducts revealed preferred bond formation at the C-terminal residue of the target peptide. Site-selective carbene insertion was achieved by placing the L* residue in different positions along the photopeptide chain, and the residues in the target peptide undergoing carbene insertion were identified by gas-phase ion sequencing that was aided by specific (13)C labeling. Density functional theory calculations indicated that noncovalent binding to GL*L*L*K resulted in substantial changes of the (GLLLK + H)(+) ground state conformation. The peptide moieties in [GL*L*LK + GLLLK + H](+) ion complexes were held together by hydrogen bonds, whereas dispersion interactions of the nonpolar groups were only secondary in ground-state 0 K structures. Born-Oppenheimer molecular dynamics for 100 ps trajectories of several different conformers at the 310 K laboratory temperature showed that noncovalent complexes developed multiple, residue-specific contacts between the diazirine carbons and GLLLK residues. The calculations pointed to the substantial fluidity of the nonpolar side chains in the complexes. Diazirine photochemistry in combination with Born-Oppenheimer molecular dynamics is a promising tool for investigations of peptide-peptide ion interactions in the gas phase. Graphical Abstract ᅟ. PMID:26817657

  14. Phase Studies of Model Biomembranes: Complex Behavior of DSPC/DOPC/Cholesterol

    PubMed Central

    Zhao, Jiang; Wu, Jing; Heberle, Frederick A.; Mills, Thalia T.; Klawitter, Paul; Huang, Grace; Costanza, Greg; Feigenson, Gerald W.

    2009-01-01

    We have undertaken a series of experiments to examine the behavior of individual components of cell membranes. Here we report an initial stage of these experiments, in which the properties of a chemically simple lipid mixture are carefully mapped onto a phase diagram. Four different experimental methods were used to establish the phase behavior of the 3-component mixture DSPC/DOPC/chol: (1) confocal fluorescence microscopy observation of giant unilamellar vesicles, GUVs; (2) FRET from perylene to C20:0-DiI; (3) fluorescence of dilute dyes C18:2-DiO and C20:0-DiI; and (4) wide angle x-ray diffraction. This particular 3-component mixture was chosen, in part, for a high level of immiscibility of the components in order to facilitate solving the phase behavior at all compositions. At 23 °C, a large fraction of the possible compositions for this mixture give rise to a solid phase. A region of 3-phase coexistence of {Lα + Lβ + Lo} was detected and defined based on a combination of fluorescence microscopy of GUVs, FRET, and dilute C20:0-DiI fluorescence. At very low cholesterol concentrations, the solid phase is the tilted-chain phase Lβ′. Most of the phase boundaries have been determined to within a few percent of the composition. Measurements of the perturbations of the boundaries of this accurate phase diagram could serve as a means to understand the behaviors of a range of added lipids and proteins. PMID:17825247

  15. Low-complexity feed-forward carrier phase estimation for M-ary QAM based on phase search acceleration by quadratic approximation.

    PubMed

    Xiang, Meng; Fu, Songnian; Deng, Lei; Tang, Ming; Shum, Perry; Liu, Deming

    2015-07-27

    Blind phase search (BPS) algorithm for M-QAM has excellent tolerance to laser linewidth at the expense of rather high computation complexity (CC). Here, we first theoretically obtain the quadratic relationship between the test angle and corresponding distance matric during the BPS implementation. Afterwards, we propose a carrier phase estimation (CPE) based on a two-stage BPS with quadratic approximation (QA). Instead of searching the phase blindly with fixed step-size for the BPS algorithm, QA can significantly accelerate the speed of phase searching. As a result, a group factor of 2.96/3.05, 4.55/4.67 and 2.27/2.3 (in the form of multipliers/adders) reduction of CC is achieved for 16QAM, 64QAM and 256QAM, respectively, in comparison with the traditional BPS scheme. Meanwhile, a guideline for determining the summing filter block length is put forward during performance optimization. Under the condition of optimum filter block length, our proposed scheme shows similar performance as traditional BPS scheme. At 1 dB required E(S)/N(0) penalty @ BER = 10(-2), our proposed CPE scheme can tolerate a times symbol duration productΔf⋅T(S) of 1.7 × 10(-4), 6 × 10(-5) and 1.5 × 10(-5) for 16/64/256-QAM, respectively. PMID:26367577

  16. Agent-based spin model for financial markets on complex networks: Emergence of two-phase phenomena

    NASA Astrophysics Data System (ADS)

    Kim, Yup; Kim, Hong-Joo; Yook, Soon-Hyung

    2008-09-01

    We study a microscopic model for financial markets on complex networks, motivated by the dynamics of agents and their structure of interaction. The model consists of interacting agents (spins) with local ferromagnetic coupling and global antiferromagnetic coupling. In order to incorporate more realistic situations, we also introduce an external field which changes in time. From numerical simulations, we find that the model shows two-phase phenomena. When the local ferromagnetic interaction is balanced with the global antiferromagnetic interaction, the resulting return distribution satisfies a power law having a single peak at zero values of return, which corresponds to the market equilibrium phase. On the other hand, if local ferromagnetic interaction is dominant, then the return distribution becomes double peaked at nonzero values of return, which characterizes the out-of-equilibrium phase. On random networks, the crossover between two phases comes from the competition between two different interactions. However, on scale-free networks, not only the competition between the different interactions but also the heterogeneity of underlying topology causes the two-phase phenomena. Possible relationships between the critical phenomena of spin system and the two-phase phenomena are discussed.

  17. Information geometric analysis of phase transitions in complex patterns: the case of the Gray-Scott reaction–diffusion model

    NASA Astrophysics Data System (ADS)

    Har-Shemesh, Omri; Quax, Rick; Hoekstra, Alfons G.; Sloot, Peter M. A.

    2016-04-01

    The Fisher–Rao metric from information geometry is related to phase transition phenomena in classical statistical mechanics. Several studies propose to extend the use of information geometry to study more general phase transitions in complex systems. However, it is unclear whether the Fisher–Rao metric does indeed detect these more general transitions, especially in the absence of a statistical model. In this paper we study the transitions between patterns in the Gray-Scott reaction–diffusion model using Fisher information. We describe the system by a probability density function that represents the size distribution of blobs in the patterns and compute its Fisher information with respect to changing the two rate parameters of the underlying model. We estimate the distribution non-parametrically so that we do not assume any statistical model. The resulting Fisher map can be interpreted as a phase-map of the different patterns. Lines with high Fisher information can be considered as boundaries between regions of parameter space where patterns with similar characteristics appear. These lines of high Fisher information can be interpreted as phase transitions between complex patterns.

  18. Phase-field simulations of GaN growth by selective area epitaxy from complex mask geometries

    NASA Astrophysics Data System (ADS)

    Aagesen, Larry K.; Coltrin, Michael E.; Han, Jung; Thornton, Katsuyo

    2015-05-01

    Three-dimensional phase-field simulations of GaN growth by selective area epitaxy were performed. The model includes a crystallographic-orientation-dependent deposition rate and arbitrarily complex mask geometries. The orientation-dependent deposition rate can be determined from experimental measurements of the relative growth rates of low-index crystallographic facets. Growth on various complex mask geometries was simulated on both c-plane and a-plane template layers. Agreement was observed between simulations and experiment, including complex phenomena occurring at the intersections between facets. The sources of the discrepancies between simulated and experimental morphologies were also investigated. The model provides a route to optimize masks and processing conditions during materials synthesis for solar cells, light-emitting diodes, and other electronic and opto-electronic applications.

  19. Phase-field simulations of GaN growth by selective area epitaxy from complex mask geometries

    SciTech Connect

    Aagesen, Larry K.; Thornton, Katsuyo; Coltrin, Michael E.; Han, Jung

    2015-05-21

    Three-dimensional phase-field simulations of GaN growth by selective area epitaxy were performed. The model includes a crystallographic-orientation-dependent deposition rate and arbitrarily complex mask geometries. The orientation-dependent deposition rate can be determined from experimental measurements of the relative growth rates of low-index crystallographic facets. Growth on various complex mask geometries was simulated on both c-plane and a-plane template layers. Agreement was observed between simulations and experiment, including complex phenomena occurring at the intersections between facets. The sources of the discrepancies between simulated and experimental morphologies were also investigated. The model provides a route to optimize masks and processing conditions during materials synthesis for solar cells, light-emitting diodes, and other electronic and opto-electronic applications.

  20. Phase-field simulations of GaN growth by selective area epitaxy on complex mask geometries

    DOE PAGESBeta

    Aagesen, Larry K.; Coltrin, Michael Elliott; Han, Jung; Thornton, Katsuyo

    2015-05-15

    Three-dimensional phase-field simulations of GaN growth by selective area epitaxy were performed. Furthermore, this model includes a crystallographic-orientation-dependent deposition rate and arbitrarily complex mask geometries. The orientation-dependent deposition rate can be determined from experimental measurements of the relative growth rates of low-index crystallographic facets. Growth on various complex mask geometries was simulated on both c-plane and a-plane template layers. Agreement was observed between simulations and experiment, including complex phenomena occurring at the intersections between facets. The sources of the discrepancies between simulated and experimental morphologies were also investigated. We found that the model provides a route to optimize masks andmore » processing conditions during materials synthesis for solar cells, light-emitting diodes, and other electronic and opto-electronic applications.« less

  1. Phase-field simulations of GaN growth by selective area epitaxy on complex mask geometries

    SciTech Connect

    Aagesen, Larry K.; Coltrin, Michael Elliott; Han, Jung; Thornton, Katsuyo

    2015-05-15

    Three-dimensional phase-field simulations of GaN growth by selective area epitaxy were performed. Furthermore, this model includes a crystallographic-orientation-dependent deposition rate and arbitrarily complex mask geometries. The orientation-dependent deposition rate can be determined from experimental measurements of the relative growth rates of low-index crystallographic facets. Growth on various complex mask geometries was simulated on both c-plane and a-plane template layers. Agreement was observed between simulations and experiment, including complex phenomena occurring at the intersections between facets. The sources of the discrepancies between simulated and experimental morphologies were also investigated. We found that the model provides a route to optimize masks and processing conditions during materials synthesis for solar cells, light-emitting diodes, and other electronic and opto-electronic applications.

  2. Surface complexation reaction for phase transfer of hydrophobic quantum dot from nonpolar to polar medium.

    PubMed

    Bhandari, Satyapriya; Roy, Shilaj; Pramanik, Sabyasachi; Chattopadhyay, Arun

    2014-09-01

    Chemical reaction between oleate-capped Zn(x)Cd(1-x)S quantum dots (Qdots) and 8-hydroxyquinoline (HQ) led to formation of a surface complex, which was accompanied by transfer of hydrophobic Qdots from nonpolar (hexane) to polar (water) medium with high efficiency. The stability of the complex on the surface was achieved via involvement of dangling sulfide bonds. Moreover, the transferred hydrophilic Qdots--herein called as quantum dot complex (QDC)--exhibited new and superior optical properties in comparison to bare inorganic complexes with retention of the dimension and core structure of the Qdots. Finally, the new and superior optical properties of water-soluble QDC make them potentially useful for biological--in addition to light emitting device (LED)--applications. PMID:25133937

  3. New Pathways for the Formation of Complex Organics and Prebiotic Synthesis in the Gas Phase

    NASA Astrophysics Data System (ADS)

    El-Shall, M. S.

    2010-04-01

    We study the formation mechanisms of complex organics that are present in interstellar clouds. The reaction of acetylene ion with water produces vinyl alcohol while the reaction of benzene ion with acetylene produces naphthalene-type ion.

  4. Theoretical Investigation of OCN(-) Charge Transfer Complexes in Condensed Phase Media: Spectroscopic Properties in Amorphous Ice

    NASA Technical Reports Server (NTRS)

    Park, Jin-Young; Woon, David E.

    2004-01-01

    Density functional theory (DFT) calculations of cyanate (OCN(-)) charge-transfer complexes were performed to model the "XCN" feature observed in interstellar icy grain mantles. OCN(-) charge-transfer complexes were formed from precursor combinations of HNCO or HOCN with either NH3 or H2O. Three different solvation strategies for realistically modeling the ice matrix environment were explored, including (1) continuum solvation, (2) pure DFT cluster calculations, and (3) an ONIOM DFT/PM3 cluster calculation. The model complexes were evaluated by their ability to reproduce seven spectroscopic measurements associated with XCN: the band origin of the OCN(-) asymmetric stretching mode, shifts in that frequency due to isotopic substitutions of C, N, O, and H, plus two weak features. The continuum solvent field method produced results consistent with some of the experimental data but failed to account for other behavior due to its limited capacity to describe molecular interactions with solvent. DFT cluster calculations successfully reproduced the available spectroscopic measurements very well. In particular, the deuterium shift showed excellent agreement in complexes where OCN(-) was fully solvated. Detailed studies of representative complexes including from two to twelve water molecules allowed the exploration of various possible solvation structures and provided insights into solvation trends. Moreover, complexes arising from cyanic or isocyanic acid in pure water suggested an alternative mechanism for the formation of OCN(-) charge-transfer complexes without the need for a strong base such as NH3 to be present. An extended ONIOM (B3LYP/PM3) cluster calculation was also performed to assess the impact of a more realistic environment on HNCO dissociation in pure water.

  5. The complexity of consenting to clinical research in phase I pediatric cancer studies.

    PubMed

    Schechter, Tal; Grant, Ronald

    2015-02-01

    The principal aim of phase I studies is to define the recommended dosing of drugs for phase II studies through assessment of drug pharmacokinetics and observation of the drug's toxicity profile. In the setting of pediatric oncology, the use of an experimental drug in phase I study is offered when prognosis is poor. Thus, phase I oncology studies are not given to patients with a primary purpose of an intent to cure. They may offer little to no treatment benefit and carry a potential toxic effect. They may offer other benefits such as improved quality of life and relief of pain, however. Three parties are involved in the informed consent process: the parents, patients, and physicians. Families report hope as the main cause for enrollment. Physicians focus on providing information so families can decide about participation. Physicians also try to maintain hope despite understanding the nature of the disease. This makes the informed consent complicated for all parties involved in the process. The purpose of this review is to discuss the aims of phase I studies in pediatric oncology and to convey the ethical challenges that patients, parents, and physicians are facing when discussing informed consent with potential study participants. PMID:25573671

  6. Ligand field spectroscopy of Cu(II) and Ag(II) complexes in the gas phase: theory and experiment.

    PubMed

    Puskar, Ljiljana; Cox, Hazel; Goren, Alan; Aitken, Georgina D C; Stace, Anthony J

    2003-01-01

    Ligand field spectra have been recorded in the gas phase for the two series of complexes containing either Cu(II) or Ag(II) in association with pyridine. Where comparisons are possible, the gas phase spectra match those recorded in the condensed phase; however, for Ag(II) systems the results differ in interpretation. The Ag(II) data are attributed to a ligand-to-metal charge transfer process, and the Cu(II) data (spectral region and extinction coefficient) match the characteristics of a d-d transition. A detailed theoretical analysis of two complexes. [Cu(py)4]2+ and [Ag(py)4]2+ provides evidence of a minimum energy, D4h structure and two less stable D2h and D2d structures within approximately 60 kJ mol(-1). From these structures it is possible to identify a range of optically and vibronically allowed transitions that could contribute to spectra observed in the gas phase. In the case of calculations on [Ag(py)4]2+ there is strong evidence of an electronic transition that would account for the observation of charge transfer in the experiments. Less detailed calculations on [Cu(py)6]2+ and [Ag(py)6]2+ show structural evidence of extensive Jahn Teller distortion. Taken together with incremental binding energies calculated for complexes containing between two and six pyridine molecules, these results show that the level of theory adopted is capable of providing a semi-quantitative understanding of the experimental data. PMID:14527220

  7. Volta phase plate cryo-EM of the small protein complex Prx3.

    PubMed

    Khoshouei, Maryam; Radjainia, Mazdak; Phillips, Amy J; Gerrard, Juliet A; Mitra, Alok K; Plitzko, Jürgen M; Baumeister, Wolfgang; Danev, Radostin

    2016-01-01

    Cryo-EM of large, macromolecular assemblies has seen a significant increase in the numbers of high-resolution structures since the arrival of direct electron detectors. However, sub-nanometre resolution cryo-EM structures are rare compared with crystal structure depositions, particularly for relatively small particles (<400 kDa). Here we demonstrate the benefits of Volta phase plates for single-particle analysis by time-efficient cryo-EM structure determination of 257 kDa human peroxiredoxin-3 dodecamers at 4.4 Å resolution. The Volta phase plate improves the applicability of cryo-EM for small molecules and accelerates structure determination. PMID:26817416

  8. Volta phase plate cryo-EM of the small protein complex Prx3

    NASA Astrophysics Data System (ADS)

    Khoshouei, Maryam; Radjainia, Mazdak; Phillips, Amy J.; Gerrard, Juliet A.; Mitra, Alok K.; Plitzko, Jürgen M.; Baumeister, Wolfgang; Danev, Radostin

    2016-01-01

    Cryo-EM of large, macromolecular assemblies has seen a significant increase in the numbers of high-resolution structures since the arrival of direct electron detectors. However, sub-nanometre resolution cryo-EM structures are rare compared with crystal structure depositions, particularly for relatively small particles (<400 kDa). Here we demonstrate the benefits of Volta phase plates for single-particle analysis by time-efficient cryo-EM structure determination of 257 kDa human peroxiredoxin-3 dodecamers at 4.4 Å resolution. The Volta phase plate improves the applicability of cryo-EM for small molecules and accelerates structure determination.

  9. Origin of non-linearity in phase solubility: solubilisation by cyclodextrin beyond stoichiometric complexation.

    PubMed

    Nicol, Thomas W J; Matubayasi, Nobuyuki; Shimizu, Seishi

    2016-06-01

    The low solubility of drugs, which poses a serious problem in drug development, can in part be overcome by the use of cyclodextrins (CDs) and their derivatives. Here, the key to solubilisation is identified as the formation of inclusion complexes with the drug molecule. If inclusion complexation were the only contribution to drug solubility, it would increase linearly with CD concentration (as per the Higuchi-Connors model); this is because inclusion complexation is a 1 : 1 stoichiometric process. However, solubility curves often deviate from this linearity, whose mechanism is yet to be understood. Here we aim to clarify the origin of such non-linearity, based on the Kirkwood-Buff and the McMillan-Mayer theories of solutions. The rigorous statistical thermodynamic theory shows that non-linearity of solubilisation can be rationalised by two contributions: CD-drug interaction and the drug-induced change of CD-CD interaction. PMID:27206059

  10. Calibration of the complex matrix effects on the sampling of polycyclic aromatic hydrocarbons in milk samples using solid phase microextraction.

    PubMed

    Lin, Wei; Wei, Songbo; Jiang, Ruifen; Zhu, Fang; Ouyang, Gangfeng

    2016-08-24

    Solid phase microextraction (SPME), a simple, fast and promising sampling technique, has been widely used for complex sample analysis. However, complex matrices could modify the absorption property of coatings as well as the uptake kinetics of analytes, eventually biasing the quantification results. In the current study, we demonstrated the feasibility of a developed calibration method for the analysis of polycyclic aromatic hydrocarbons (PAHs) in complex milk samples. Effects of the complex matrices on the SPME sampling process and the sampling conditions were investigated. Results showed that short exposure time (pre-equilibrium SPME, PE-SPME) could increase the lifetime of coatings, and the complex matrices in milk samples could significantly influence the sampling kinetics of SPME. In addition, the optimized sampling time, temperature and dilution factor for PAHs were 10 min, 85 °C and 20, respectively. The obtained LODs and LOQs of all the PAHs were 0.1-0.8 ng/mL and 1.4-4.7 ng/mL, respectively. Furthermore, the accuracy of the proposed PE-SPME method for milk sampling was validated by the recoveries of the studied compounds in two concentration levels, which ranged from 75% to 110% for all the compounds. Finally, the proposed method was applied to the screening of PAHs in milk samples. PMID:27497004

  11. "Sounds of Intent", Phase 2: Gauging the Music Development of Children with Complex Needs

    ERIC Educational Resources Information Center

    Ockelford, A.; Welch, G.; Jewell-Gore, L.; Cheng, E.; Vogiatzoglou, A.; Himonides, E.

    2011-01-01

    This article reports the latest phase of research in the "Sounds of intent" project, which is seeking, as a long-term goal, to map musical development in children and young people with severe, or profound and multiple learning difficulties (SLD or PMLD). Previous exploratory work had resulted in a framework of six putative music-developmental…

  12. Separation of dialkyl sulfides by metallo-mesogenic stationary phases for complexation gas chromatography.

    PubMed

    Chen, Jian-Lian; Liu, Chuen-Ying

    2007-08-17

    A copper mesogenic side-chain polymer (P-C(15)CuC(18)) was cross-linked onto the capillary wall as a stationary film for gas chromatography (GC) separation of alkyl sulfides. These organic sulfides are of interest for their large health impact because of their wide range of volatiles and high reactivities toward metals. Different GC parameters for optimal separation efficiency are discussed for use with a mesogenic polymer column along with flame photometric detection (FPD). Both the carrier gas flow-rate and column temperature were studied to determine the relationship of plate height to the chemical structure of the solutes, as well as to determine the morphology of the mesogenic polymer. Van 't Hoff plots show phase transitions of the stationary mesophase as the column temperature was varied. The results reveal that the separation mechanism might be based on ligand exchange and polarity interaction between the analytes and the stationary phase, with the vapor pressure of the analytes also being important. The former interaction dominates in the lamellar crystalline phase and the latter interaction dominates in the hexagonal columnar-discotic phase. With high reproducibility for retention time (RSD< or =0.37%) and for peak area (RSD< or =5.16%), the GC-FPD system produced linear calibration graphs (r> or =0.9918) for the determination of 13 sulfides with a detection limit below 2.5 ng. PMID:17568598

  13. A comparative study of penalization and phase field methods for the solution of the diffusion equation in complex geometries

    NASA Astrophysics Data System (ADS)

    Tauriello, Gerardo; Koumoutsakos, Petros

    2015-02-01

    We present a comparative study of penalization and phase field methods for the solution of the diffusion equation in complex geometries embedded using simple Cartesian meshes. The two methods have been widely employed to solve partial differential equations in complex and moving geometries for applications ranging from solid and fluid mechanics to biology and geophysics. Their popularity is largely due to their discretization on Cartesian meshes thus avoiding the need to create body-fitted grids. At the same time, there are questions regarding their accuracy and it appears that the use of each one is confined by disciplinary boundaries. Here, we compare penalization and phase field methods to handle problems with Neumann and Robin boundary conditions. We discuss extensions for Dirichlet boundary conditions and in turn compare with methods that have been explicitly designed to handle Dirichlet boundary conditions. The accuracy of all methods is analyzed using one and two dimensional benchmark problems such as the flow induced by an oscillating wall and by a cylinder performing rotary oscillations. This comparative study provides information to decide which methods to consider for a given application and their incorporation in broader computational frameworks. We demonstrate that phase field methods are more accurate than penalization methods on problems with Neumann boundary conditions and we present an error analysis explaining this result.

  14. Phase diagrams of the Bose-Hubbard model and the Haldane-Bose-Hubbard model with complex hopping amplitudes

    NASA Astrophysics Data System (ADS)

    Kuno, Yoshihito; Nakafuji, Takashi; Ichinose, Ikuo

    2015-12-01

    In this paper, we study Bose-Hubbard models on square and honeycomb lattices with complex hopping amplitudes, which are feasible by recent experiments of cold atomic gases in optical lattices. To clarify phase diagrams, we use extended quantum Monte Carlo simulations (eQMC). For the system on the square lattice, the complex hopping is realized by an artificial magnetic field. We found that vortex-solid states form for certain set of magnetic field, i.e., the magnetic field with the flux quanta per plaquette f =p /q , where p and q are co-prime natural numbers. For the system on the honeycomb lattice, we add the next-nearest-neighbor complex hopping. The model is a bosonic analog of the Haldane-Hubbard model. By means of eQMC, we study the model with both weak and strong onsite repulsions. Numerical study shows that the model has a rich phase diagram. We also found that in the system defined on the honeycomb lattice of the cylinder geometry, an interesting edge state appears.

  15. First Principles Studies of Phase Stability and Reaction Dynamics in Complex Metal Hydrides

    SciTech Connect

    Chou, Mei-Yin

    2014-09-29

    Complex metal hydrides are believed to be one of the most promising materials for developing hydrogen storage systems that can operate under desirable conditions. At the same time, these are also a class of materials that exhibit intriguing properties. We have used state-of-the-art computational techniques to study the fundamental properties of these materials.

  16. Phase-Contrast versus Off-Axis Illumination: Is a More Complex Microscope Always More Powerful?

    ERIC Educational Resources Information Center

    Hostounsky, Zdenek; Pelc, Radek

    2007-01-01

    In this article, a practical demonstration suitable for any biology college classroom is presented. With the examples of a complex biological specimen (slug's radula) and a simple reference specimen (electron microscopical grid imprint in gelatin), both of which can be easily prepared, the capabilities of two imaging modes commonly used in optical…

  17. Phase 5 storage (Project W-112) Central Waste Complex operational readiness review, final report

    SciTech Connect

    Wight, R.H.

    1997-05-30

    This document is the final report for the RFSH conducted, Contractor Operational Readiness Review (ORR) for the Central Waste Complex (CWC) Project W-112 and Interim Safety Basis implementation. As appendices, all findings, observations, lines of inquiry and the implementation plan are included.

  18. Improved in vivo imaging of human blood circulation in the chorioretinal complex using phase variance method with new phase stabilized 1 μm swept-source optical coherence tomography (pv-SSOCT)

    NASA Astrophysics Data System (ADS)

    Poddar, Raju; Kim, Dae Yu; Werner, John S.; Zawadzki, Robert J.

    2014-02-01

    We demonstrate the feasibility of our newly developed phase stabilized high-speed (100 kHz A-scans/s) 1 μm sweptsource optical coherence tomography (SSOCT) system with the phase-variance based motion contrast method for visualization of human chorioretinal complex microcirculation. Compared to our previously reported spectral domain (spectrometer based) phase-variance (pv)-SDOCT system it has advantages of higher sensitivity, reduced fringe washout for high blood flow speeds and deeper penetration in choroid. High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. This process does not require additional calibration hardware and complex numerical procedures. Our phase stabilization method is simple and can be employed in a variety of SS-OCT systems. Examples of vasculature in the chorioretinal complex imaged by pv-SSOCT is presented and compared to retinal images of the same volunteers acquired with fluorescein angiography (FA) and indocyanine green angiography (ICGA).

  19. Phase Retrieval from Modulus Using Homeomorphic Signal Processing and the Complex Cepstrum: An Algorithm for Lightning Protection Systems

    SciTech Connect

    Clark, G A

    2004-06-08

    In general, the Phase Retrieval from Modulus problem is very difficult. In this report, we solve the difficult, but somewhat more tractable case in which we constrain the solution to a minimum phase reconstruction. We exploit the real-and imaginary part sufficiency properties of the Fourier and Hilbert Transforms of causal sequences to develop an algorithm for reconstructing spectral phase given only spectral modulus. The algorithm uses homeomorphic signal processing methods with the complex cepstrum. The formal problem of interest is: Given measurements of only the modulus {vert_bar}H(k){vert_bar} (no phase) of the Discrete Fourier Transform (DFT) of a real, finite-length, stable, causal time domain signal h(n), compute a minimum phase reconstruction {cflx h}(n) of the signal. Then compute the phase of {cflx h}(n) using a DFT, and exploit the result as an estimate of the phase of h(n). The development of the algorithm is quite involved, but the final algorithm and its implementation are very simple. This work was motivated by a Phase Retrieval from Modulus Problem that arose in LLNL Defense Sciences Engineering Division (DSED) projects in lightning protection for buildings. The measurements are limited to modulus-only spectra from a spectrum analyzer. However, it is desired to perform system identification on the building to compute impulse responses and transfer functions that describe the amount of lightning energy that will be transferred from the outside of the building to the inside. This calculation requires knowledge of the entire signals (both modulus and phase). The algorithm and software described in this report are proposed as an approach to phase retrieval that can be used for programmatic needs. This report presents a brief tutorial description of the mathematical problem and the derivation of the phase retrieval algorithm. The efficacy of the theory is demonstrated using simulated signals that meet the assumptions of the algorithm. We see that for

  20. Properties of clusters in the gas phase. V - Complexes of neutral molecules onto negative ions

    NASA Technical Reports Server (NTRS)

    Keesee, R. G.; Lee, N.; Castleman, A. W., Jr.

    1980-01-01

    Ion-molecules association reactions of the form A(-)(B)n-1 + B = A(-)(B)n were studied over a range of temperatures in the gas phase using high pressure mass spectrometry. Enthalpy and entropy changes were determined for the stepwise clustering reactions of (1) sulfur dioxide onto Cl(-), I(-), and NO2(-) with n ranging from one to three or four, and onto SO2(-) and SO3(-) with n equal to one; and (2) carbon dioxide onto Cl(-), I(-), NO2(-), CO3(-), and SO3(-) with n equal to one. From these data and earlier hydration results, the order of the magnitude of the enthalpy changes on the association of the first neutral for a series of negative ions was found to parallel the gas-phase basicity of those anions.

  1. Volta phase plate cryo-EM of the small protein complex Prx3

    PubMed Central

    Khoshouei, Maryam; Radjainia, Mazdak; Phillips, Amy J.; Gerrard, Juliet A.; Mitra, Alok K.; Plitzko, Jürgen M.; Baumeister, Wolfgang; Danev, Radostin

    2016-01-01

    Cryo-EM of large, macromolecular assemblies has seen a significant increase in the numbers of high-resolution structures since the arrival of direct electron detectors. However, sub-nanometre resolution cryo-EM structures are rare compared with crystal structure depositions, particularly for relatively small particles (<400 kDa). Here we demonstrate the benefits of Volta phase plates for single-particle analysis by time-efficient cryo-EM structure determination of 257 kDa human peroxiredoxin-3 dodecamers at 4.4 Å resolution. The Volta phase plate improves the applicability of cryo-EM for small molecules and accelerates structure determination. PMID:26817416

  2. Phase behavior and complex crystal structures of self-assembled tethered nanoparticle telechelics.

    PubMed

    Marson, Ryan L; Phillips, Carolyn L; Anderson, Joshua A; Glotzer, Sharon C

    2014-01-01

    Motivated by growing interest in the self-assembly of nanoparticles for applications such as photonics, organic photovoltaics, and DNA-assisted designer crystals, we explore the phase behavior of tethered spherical nanoparticles. Here, a polymer tether is used to geometrically constrain a pair of nanoparticles creating a tethered nanoparticle "telechelic". Using simulation, we examine how varying architectural features, such as the size ratio of the two end-group nanospheres and the length of the flexible tether, affects the self-assembled morphologies. We demonstrate not only that this hybrid building block maintains the same phase diversity as linear triblock copolymers, allowing for a variety of nanoparticle materials to replace polymer blocks, but also that new structures not previously reported are accessible. Our findings imply a robust underlying ordering mechanism is common among these systems, thus allowing flexibility in synthesis approaches to achieve a target morphology. PMID:24641517

  3. Broadband terahertz wave deflection based on C-shape complex metamaterials with phase discontinuities.

    PubMed

    Zhang, Xueqian; Tian, Zhen; Yue, Weisheng; Gu, Jianqiang; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

    2013-09-01

    A broadband terahertz wave deflector based on metasurface induced phase discontinuities is reported. Various frequency components ranging from 0.43 to 1.0 THz with polarization orthogonal to the incidence are deflected into a broad range of angles from 25° to 84°. A Fresnel zone plate consequently developed from the beam deflector is capable of focusing a broadband terahertz radiation. PMID:23787976

  4. Ultrasound temporal-spatial phase-interference in complex composite media; a comparison of experimental measurement and simulation prediction.

    PubMed

    Al-Qahtani, Saeed M; Langton, Christian M

    2016-09-01

    The propagation of ultrasound through solid:liquid complex composite media such as cancellous bone suffers from a lack of a comprehensive understanding of the dependence upon density and structure. Assuming that a propagating ultrasound wave may be considered as an array of parallel sonic rays, we may determine the transit time of each by the relative proportion of the two constituents. A transit time spectrum (TTS) describes the proportion of sonic rays having a particular transit time between the minimum (tmin) and maximum (tmax) values; representing, for example, entire bone tissue and marrow respectively in the case of cancellous bone. Langton has proposed that the primary ultrasound attenuation mechanism in such media is phase-interference. The phase-interference of two or more ultrasound pulses detected at a phase-sensitive transducer has both temporal and spatial components. The temporal component is primarily dependent upon the transit time difference (dt) between the pulses and the propagating pulse-length (PL). The spatial component is primarily dependent upon the lateral separation (ds) of the detectedpulses of differing transit time and the lateral dimension of the ultrasound receive transducer aperture (dL). The aim of the paper was to explore these temporal and spatial dependencies through a comparison of experimental measurement and computer simulation in solid:liquid models of varying temporal and spatial complexity. Transmission measurements at nominal ultrasound frequencies of 1MHz and 5MHz were performed, thereby investigating the dependency upon period. The results demonstrated an overall agreement between experimental measurement and computer simulation of 87±16% and 85±12% for temporal and spatial components respectively. It is envisaged that a comprehensive understanding of ultrasound propagation through complex structures such as cancellous bone could provide an improved non-invasive tool for osteoporosis assessment. PMID:27318839

  5. Morphological and phase evolution of TiO 2 nanocrystals prepared from peroxotitanate complex aqueous solution: Influence of acetic acid

    NASA Astrophysics Data System (ADS)

    Chang, Jeong Ah; Vithal, Muga; Baek, In Chan; Seok, Sang Il

    2009-04-01

    Nanosized anatase and rutile TiO 2 having different shape, phase and size have been prepared from aqueous solutions of peroxo titanium complex starting from titanium(IV) isopropoxide (TTIP), acetic acid and hydrogen peroxide (H 2O 2) in water/isopropanol media by a facile sol-gel process. The TiO 2 nanocrystals are characterized by powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, TEM, high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) techniques. The influence of pH and the sequence of addition of reaction contents on the phase and morphology of TiO 2 are studied. The reasons for the observation of only anatase and/or mixture of anatase and rutile are given.

  6. Complex surface three-dimensional shape measurement method based on defocused Gray code plus phase-shifting

    NASA Astrophysics Data System (ADS)

    Zeng, Zhuohuan; Fu, Yanjun; Li, Biao; Chai, Minggang

    2016-08-01

    Binary pattern defocused projection method can overcome the nonlinear gamma of the projector, as well as filter high harmonics and high-frequency noise. However, high-accuracy three-dimensional (3-D) shape measurement of complex surface using it still remains a challenge. Therefore, a novel Gray code plus phase-shifting method based on defocusing is proposed to solve the problem. The edges of Gray code patterns become blurred owing to defocus, which makes the recovery of accurate Gray code patterns difficult. To solve this problem, the positive and inverse Gray code patterns are projected to obtain threshold values, which are used to achieve the binarization of Gray code patterns. This method is robust and suitable for different defocus levels. Compared with the traditional Gray code plus phase-shifting method, the experimental results prove the effectiveness and feasibility of the proposed method.

  7. Gas-phase unfolding and disassembly reveals stability differences in ligand-bound multiprotein complexes.

    PubMed

    Hyung, Suk-Joon; Robinson, Carol V; Ruotolo, Brandon T

    2009-04-24

    Mass spectrometry (MS) is widely used to assess the binding of small molecules to proteins and their complexes. In many cases, subtle differences in the stability afforded by binding of ligands to protein assemblies cannot be detected by MS. Here we show that monitoring the unfolding of protein subunits, using ion mobility-MS, allows differentiation of the effects of ligand binding not normally observed by MS alone. Using wild-type and disease-associated variants of tetrameric transthyretin, MS data indicate that populations of the variant protein are less stable than wild-type. Ion mobility-MS, however, is able to show that the natural ligand of transthyretin, thyroxine, provides a larger stability increase to the tetramer composed of variant subunits than to the wild-type protein-ligand complex. Overall, therefore, our results have implications for small-molecule drug design directed at multiprotein targets. PMID:19389624

  8. Effects of phase I complex decongestive physiotherapy on physical functions and depression levels in breast cancer related lymph edema

    PubMed Central

    Atalay, Orçin Telli; Özkir, Anıl; Çalik, Bilge Başakçi; Baskan, Emre; Taşkin, Harun

    2015-01-01

    [Purpose] Breast cancer-related upper extremity lymph edema is known to cause physical, functional and psychological impairments in women after modified radical mastectomy. The aim of this study was to investigate the effects of phase I Complex Decongestive Physiotherapy (CDP) on physical functions and depression levels in women with breast cancer-related upper extremity lymph edema. [Subjects and Methods] Fifty-eight subjects with breast cancer-related upper extremity lymph edema were the subjects of this study. The arm circumference, shoulder range of motion (ROM), muscle strength and depression levels of the subjects were assessed before and after phase I CDP treatment. [Results] After phase I CDP, there was a statistically significant reduction in circumference measurements at all levels of the affected arm. There was not any statistically significant difference in muscle strength after CDP. The shoulder ROM improved after treatment. There was a significant reduction in the Beck Depression Inventory score. A significant positive correlation was found between depression levels and circumference measurement. [Conclusion] Based on the results we suggest that by reducing limb volume, beside improving physical functions, phase I CDP can affect psychological status, especially depression which is very common in women with breast cancer-related upper extremity lymph edema. PMID:25931748

  9. Deposition of rare-earth phosphate, fluoride, and oxysulfide films by gas-phase thermolysis of {beta}-diketonate complexes

    SciTech Connect

    Gorshkov, N.I.; Suglobov, D.N.; Sidorenko, G.V.

    1995-07-01

    Rare-earth fluoride, phosphate, and oxysulfide films have been obtained by gas-phase thermolysis of appropriate rare-earth mixed-ligand and tris-chelate {beta}-diketonate complexes. Gas-phase thermolysis of Ln(PTFA){sub 3} {center_dot}HMPA and Ln(HFA){sub 3}{center_dot}2HMPA (PTFA is pivaloyltrifluoroacetonate ligand and HFA is hexafluoracetylacetonate ligand, HMPA is hexamethylphosphoric triamide, Ln = Nd, Eu, Er) in a flow of air or N{sub 2}O yields a finely dispersed phosphate phase. Thermolysis of Ln(HFA){sub 3} {center_dot}DME (Ln = Nd, Eu, Er, DME is 1,2-dimethoxyethane) yields carbon-free fluoride films, whereas in the case of Er(HFA){sub 3}{center_dot}2H{sub 2}O and Er(PTFA){sub 3} erbium oxyfluoride and oxide films are deposited. Thermolysis of Nd(DPM){sub 3} (DPM is dipivaloylmethanate ligand) in hydrogen sulfide flow yields and Nd{sub 2}O{sub 2}S phase.

  10. Complexity of spatiotemporal traffic phenomena in flow of identical drivers: Explanation based on fundamental hypothesis of three-phase theory

    NASA Astrophysics Data System (ADS)

    Kerner, Boris S.

    2012-03-01

    Based on numerical simulations of a stochastic three-phase traffic flow model, we reveal the physics of the fundamental hypothesis of three-phase theory that, in contrast with a fundamental diagram of classical traffic flow theories, postulates the existence of a two-dimensional (2D) region of steady states of synchronized flow where a driver makes an arbitrary choice of a space gap (time headway) to the preceding vehicle. We find that macroscopic and microscopic spatiotemporal effects of the entire complexity of traffic congestion observed up to now in real measured traffic data can be explained by simulations of traffic flow consisting of identical drivers and vehicles, if a microscopic model used in these simulations incorporates the fundamental hypothesis of three-phase theory. It is shown that the driver's choice of space gaps within the 2D region of synchronized flow associated with the fundamental hypothesis of three-phase theory can qualitatively change types of congested patterns that can emerge at a highway bottleneck. In particular, if drivers choose long enough spaces gaps associated with the fundamental hypothesis, then general patterns, which consist of synchronized flow and wide moving jams, do not emerge independent of the flow rates and bottleneck characteristics: Even at a heavy bottleneck leading to a very low speed within congested patterns, only synchronized flow patterns occur in which no wide moving jams emerge spontaneously.

  11. Coherence and polarization of electromagnetic beams modulated by random phase screens and their changes through complex ABCD optical systems.

    PubMed

    Hanson, Steen G; Wang, Wei; Jakobsen, Michael L; Takeda, Mitsuo

    2008-09-01

    The change of coherence and polarization of an electromagnetic beam modulated by a random anisotropic phase screen passing through any optical system is found within the framework of complex ABCD-matrix theory This means that the formalism can treat imaging and Fourier transform and free-space optical systems, as well as fractional Fourier transform systems, with finite-size limiting apertures of Gaussian transmission shape. Thus, the current paper shall be considered as a continuation, extension, and generalization of a previous work by Shirai and Wolf [J. Opt. Soc. Am. A21, 1907 (2004)]. It will be shown that the inclusion of apertures in the optical system strongly influences not only the propagation of spatial coherence but also the degree of polarization of a propagating field. Analytical expressions of coherence and polarization propagation will be given in terms of the matrix elements for any complex optical system. PMID:18758562

  12. An Unexpected Gas-Phase Binding Motif for Metal Dication Complexation with Peptides: Irmpd Spectroscopic Structure Determination

    NASA Astrophysics Data System (ADS)

    Dunbar, Robert C.; Steill, Jeffrey; Polfer, Nicolas; Berden, Giel; Oomens, Jos

    2011-06-01

    The favorable orientation of the amide linkage and the aromatic side chain of N-terminal Phe or Trp leads to several favorable motifs for metal ion binding to dipeptides, having distinct characteristics in the IR spectrum. Infrared multiple photon photodissociation spectroscopy using the FELIX free electron laser has enabled clear resolution of these isomeric forms. The spectral patterns of complexes of small dications (Mg2+, Ni2+ and Co2+) reveal an unexpected new isomeric form, in which the metal ion displaces the amide hydrogen, forming a metal-nitrogen bond with covalent character which is unprecedented in such gas-phase complexes. Spectra of the ions were acquired by irradiating the cell of the Fourier-transform ion cyclotron resonance mass spectrometer with infrared light from the FELIX laser at wavelengths in the approximate range 500 to 1900 Cm-1.

  13. Menstrual cycle phase alters women's sexual preferences for composers of more complex music.

    PubMed

    Charlton, Benjamin D

    2014-06-01

    Over 140 years ago Charles Darwin first argued that birdsong and human music, having no clear survival benefit, were obvious candidates for sexual selection. Whereas the first contention is now universally accepted, his theory that music is a product of sexual selection through mate choice has largely been neglected. Here, I provide the first, to my knowledge, empirical support for the sexual selection hypothesis of music evolution by showing that women have sexual preferences during peak conception times for men that are able to create more complex music. Two-alternative forced-choice experiments revealed that woman only preferred composers of more complex music as short-term sexual partners when conception risk was highest. No preferences were displayed when women chose which composer they would prefer as a long-term partner in a committed relationship, and control experiments failed to reveal an effect of conception risk on women's preferences for visual artists. These results suggest that women may acquire genetic benefits for offspring by selecting musicians able to create more complex music as sexual partners, and provide compelling support for Darwin's assertion 'that musical notes and rhythm were first acquired by the male or female progenitors of mankind for the sake of charming the opposite sex'. PMID:24759864

  14. Menstrual cycle phase alters women's sexual preferences for composers of more complex music

    PubMed Central

    Charlton, Benjamin D.

    2014-01-01

    Over 140 years ago Charles Darwin first argued that birdsong and human music, having no clear survival benefit, were obvious candidates for sexual selection. Whereas the first contention is now universally accepted, his theory that music is a product of sexual selection through mate choice has largely been neglected. Here, I provide the first, to my knowledge, empirical support for the sexual selection hypothesis of music evolution by showing that women have sexual preferences during peak conception times for men that are able to create more complex music. Two-alternative forced-choice experiments revealed that woman only preferred composers of more complex music as short-term sexual partners when conception risk was highest. No preferences were displayed when women chose which composer they would prefer as a long-term partner in a committed relationship, and control experiments failed to reveal an effect of conception risk on women's preferences for visual artists. These results suggest that women may acquire genetic benefits for offspring by selecting musicians able to create more complex music as sexual partners, and provide compelling support for Darwin's assertion ‘that musical notes and rhythm were first acquired by the male or female progenitors of mankind for the sake of charming the opposite sex’. PMID:24759864

  15. Vibrational Spectroscopy of Mass-Selected [UO2(ligand)n]2+ Complexes in the Gas Phase: Comparison with Theory

    SciTech Connect

    Gary S. Groenewold; Anita K. Gianotto

    2006-03-01

    The gas-phase infrared spectra of discrete uranyl ([UO2]2+) complexes ligated with acetone and/or acetonitrile were used to evaluate systematic trends of ligation on the position of the OdUdO stretch and to enable rigorous comparison with the results of computational studies. Ionic uranyl complexes isolated in a Fourier transform ion cyclotron resonance mass spectrometer were fragmented via infrared multiphoton dissociation using a free electron laser scanned over the mid-IR wavelengths. The asymmetric OdUdO stretching frequency was measured at 1017 cm-1 for [UO2(CH3COCH3)2]2+ and was systematically red shifted to 1000 and 988 cm-1 by the addition of a third and fourth acetone ligand, respectively, which was consistent with increased donation of electron density to the uranium center in complexes with higher coordination number. The values generated computationally using LDA, B3LYP, and ZORA-PW91 were in good agreement with experimental measurements. In contrast to the uranyl frequency shifts, the carbonyl frequencies of the acetone ligands were progressively blue shifted as the number of ligands increased from two to four and approached that of free acetone. This observation was consistent with the formation of weaker noncovalent bonds between uranium and the carbonyl oxygen as the extent of ligation increases. Similar trends were observed for [UO2(CH3CN)n]2+ complexes, although the uranyl asymmetric stretching frequencies were greater than those measured for acetone complexes having equivalent coordination, which is consistent with the fact that acetonitrile is a weaker nucleophile than is acetone. This conclusion was confirmed by the uranyl stretching frequencies measured for mixed acetone/acetonitrile complexes, which showed that substitution of one acetone for one acetonitrile produced a modest red shift of 3-6 cm-1.

  16. Experimental and Theoretical Studies on the Fragmentation of Gas-Phase Uranyl-, Neptunyl- and Plutonyl-Diglycolamide Complexes

    SciTech Connect

    Gong, Yu; Hu, Han-Shi; Rao, Linfeng; Li, Jun; Gibson, John K.

    2013-10-10

    Fragmentation of actinyl(VI) complexes UVIO2(L)22+, NpVIO2(L)22+ and PuVIO2(L)22+ (L = tetramethyl-3-oxa-glutaramide, TMOGA) produced by electrospray ionization was examined in the gas phase by collision induced dissociation (CID) in a quadrupole ion trap mass spectrometer. Cleavage of the C-Oether bond was observed for all three complexes, with dominant products being UVIO2(L)(L-86)+ with charge reduction, and NpVIO2(L)(L-101)2+ and PuVIO2(L)(L-101)2+ with charge conservation. The neptunyl and plutonyl complexes also exhibited substantial L+ loss to give pentavalent complexes NpVO2(L)+ and PuVO2(L)+, whereas the uranyl complex did not, consistent with the comparative An 5f-orbital energies and the AnVIO22+/AnVO2+ (An = U, Np, Pu) reduction potentials. CID of NpVO2(L)2+ and PuVO2(L)2+ was dominated by neutral ligand loss to form NpVO2(L)+ and PuVO2(L)+, which hydrated by addition of residual water in the ion trap; UVO2(L)2+ was not observed. Theoretical calculations of the structures and bonding of the AnVIO2(L)22+ complexes using density functional theory reveal that the metal centers are coordinated by six oxygen atoms from the two TMOGA ligands. The results are compared with radiolytic decomposition of TMOGA in solution.

  17. Measuring spatiotemporal intensity-and-phase complexity of multimode fiber output pulses

    NASA Astrophysics Data System (ADS)

    Guang, Zhe; Rhodes, Michelle; Trebino, Rick

    2016-03-01

    We demonstrate ultrashort pulse spatiotemporal field measurement for multimode optical fibers, using a singleframe characterization technique, called Spatially and Temporally Resolved Intensity and Phase Evaluation Device: Full Information from a Single Hologram (STRIPED FISH). We measure STRIPED FISH traces and retrieve the pulse field E(x,y,t) or equivalently E(x,y,ω), to generate movies revealing the field structure induced by propagating modes, due to their differences in field spatial distribution, modal propagation velocity and modal dispersion inside the fiber. We launch femtosecond pulses near 800nm from Ti: Sapphire laser to investigate linearly polarized modes LP01, LP11, LP02 and LP21 in multimode fibers.

  18. Ground State of Magnetic Dipoles on a Two-Dimensional Lattice: Structural Phases in Complex Plasmas

    SciTech Connect

    Feldmann, J. D.; Kalman, G. J.; Hartmann, P.; Rosenberg, M.

    2008-02-29

    We study analytically and by molecular dynamics simulations the ground state configuration of a system of magnetic dipoles fixed on a two-dimensional lattice. We find different phases, in close agreement with previous results. Building on this result and on the minimum energy requirement we determine the equilibrium lattice configuration, the magnetic order (ferromagnetic versus antiferromagnetic), and the magnetic polarization direction of a system of charged mesoscopic particles with magnetic dipole moments, in the domain where the strong electrostatic coupling leads to a crystalline ground state. Orders of magnitudes of the parameters of the system relevant to possible future dusty plasma experiments are discussed.

  19. [Solid phase microextraction (SPME) of sample preparation during of a complex biological matrix in biotransformation studies].

    PubMed

    Kroll, C; Borchert, H H

    1998-03-01

    Within the scope of the investigation of drug metabolism in keratinocytes solid phase microextraction (SPME) was investigated as a suitable method for sample preparation. The application of SPME is based on the fact, that a amount of analyte is absorbed by the polymer fiber at equilibrium, and the fiber is localized on a tip of a GC-syringe. The stable nitroxyl radical TEMPO (2,2,6,6-tetramthylpiperidine-1-oxyl) and its apolar metabolite 2,2,6,6-tetramethylpiperidine were analyzed by SPME and subsequent GC using thymol as internal standard. By means of the headspace-technique and an apolar fiber the recovery rate of TEMPO and the metabolite was nearly 100% and the precision was high. However, the results of the direct SPME were unsatisfactory. In comparison with conventional liquid/liquid extraction and solid phase extraction SPE the SPME proved the best results with regard to recovery rate and precision. Furthermore, the main advantages of SPME are the renunciation of organic solvents, the saving of time, the possibility to reuse the fiber about 100-150 times and the option for a complete automatisation of the extraction procedure. PMID:9547519

  20. Polarization screening-induced magnetic phase gradients at complex oxide interfaces.

    PubMed

    Spurgeon, Steven R; Balachandran, Prasanna V; Kepaptsoglou, Despoina M; Damodaran, Anoop R; Karthik, J; Nejati, Siamak; Jones, Lewys; Ambaye, Haile; Lauter, Valeria; Ramasse, Quentin M; Lau, Kenneth K S; Martin, Lane W; Rondinelli, James M; Taheri, Mitra L

    2015-01-01

    Thin-film oxide heterostructures show great potential for use in spintronic memories, where electronic charge and spin are coupled to transport information. Here we use a La0.7Sr0.3MnO3 (LSMO)/PbZr0.2Ti0.8O3 (PZT) model system to explore how local variations in electronic and magnetic phases mediate this coupling. We present direct, local measurements of valence, ferroelectric polarization and magnetization, from which we map the phases at the LSMO/PZT interface. We combine these experimental results with electronic structure calculations to elucidate the microscopic interactions governing the interfacial response of this system. We observe a magnetic asymmetry at the LSMO/PZT interface that depends on the local PZT polarization and gives rise to gradients in local magnetic moments; this is associated with a metal-insulator transition at the interface, which results in significantly different charge-transfer screening lengths. This study establishes a framework to understand the fundamental asymmetries of magnetoelectric coupling in oxide heterostructures. PMID:25879160

  1. Complex Method for Angular-Spectral Analysis of Volume Phase Diffraction Gratings Recorded in Photopolymers

    NASA Astrophysics Data System (ADS)

    Vojtíšek, P.; Květoň, M.; Richter, I.

    2016-02-01

    Photopolymer recording materials are nowadays widely used for recording of diffraction gratings and other diffraction elements. For obtaining the best performance of these diffraction gratings for desired applications, it is important to assess these gratings from many different perspectives. In this contribution, we present an experimental and characterization approach to an analysis of diffraction gratings recorded into photopolymer materials. This approach is able to provide a complex and very illustrative description of these gratings response and, with accordance to the theory, information about some important grating parameters, such as a spatial period, slant angle, etc., as well. This approach is based on the measurement of a grating response for a wide range of angles and wavelengths and then on the construction and subsequent analysis of maps in the angular-spectral plane. It is shown that the measurements are in a good agreement with the theoretical predictions based on either approximate (Kogelniks coupled wave theory) or rigorous (RCWA) techniques and that this approach provides complex and detailed characterization of the grating response which can be used for additional optimization or decision of applicability of measured sample gratings.

  2. Mechanistic studies on the gas-phase dehydrogenation of alkanes at cyclometalated platinum complexes.

    PubMed

    Butschke, Burkhard; Schwarz, Helmut

    2012-10-29

    In the ion/molecule reactions of the cyclometalated platinum complexes [Pt(L-H)](+) (L=2,2'-bipyridine (bipy), 2-phenylpyridine (phpy), and 7,8-benzoquinoline (bq)) with linear and branched alkanes C(n)H(2n+2) (n=2-4), the main reaction channels correspond to the eliminations of dihydrogen and the respective alkenes in varying ratios. For all three couples [Pt(L-H)](+)/C(2)H(6), loss of C(2)H(4) dominates clearly over H(2) elimination; however, the mechanisms significantly differs for the reactions of the "rollover"-cyclometalated bipy complex and the classically cyclometalated phpy and bq complexes. While double hydrogen-atom transfer from C(2)H(6) to [Pt(bipy-H)](+), followed by ring rotation, gives rise to the formation of [Pt(H)(bipy)](+), for the phpy and bq complexes [Pt(L-H)](+), the cyclometalated motif is conserved; rather, according to DFT calculations, formation of [Pt(L-H)(H(2))](+) as the ionic product accounts for C(2)H(4) liberation. In the latter process, [Pt(L-H)(H(2))(C(2)H(4))](+) (that carries H(2) trans to the nitrogen atom of the heterocyclic ligand) serves, according to DFT calculation, as a precursor from which, due to the electronic peculiarities of the cyclometalated ligand, C(2)H(4) rather than H(2) is ejected. For both product-ion types, [Pt(H)(bipy)](+) and [Pt(L-H)(H(2))](+) (L=phpy, bq), H(2) loss to close a catalytic dehydrogenation cycle is feasible. In the reactions of [Pt(bipy-H)](+) with the higher alkanes C(n)H(2n+2) (n=3, 4), H(2) elimination dominates over alkene formation; most probably, this observation is a consequence of the generation of allyl complexes, such as [Pt(C(3)H(5))(bipy)](+). In the reactions of [Pt(L-H)](+) (L=phpy, bq) with propane and n-butane, the losses of the alkenes and dihydrogen are of comparable intensities. While in the reactions of "rollover"-cyclometalated [Pt(bipy-H)](+) with C(n)H(2n+2) (n=2-4) less than 15 % of the generated product ions are formed by C-C bond-cleavage processes, this value is

  3. CAWSES November 7-8, 2004, Superstorm: Complex Solar and Interplanetary Features in the Post-Solar Maximum Phase

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Echer, Ezequiel; Guarnieri, Fernando L.; Kozyra, J. U.

    2008-01-01

    The complex interplanetary structures during 7 to 8 Nov 2004 are analyzed to identify their properties as well as resultant geomagnetic effects and the solar origins. Three fast forward shocks, three directional discontinuities and two reverse waves were detected and analyzed in detail. The three fast forward shocks 'pump' up the interplanetary magnetic field from a value of approx.4 nT to 44 nT. However, the fields after the shocks were northward, and magnetic storms did not result. The three ram pressure increases were associated with major sudden impulses (SI + s) at Earth. A magnetic cloud followed the third forward shock and the southward Bz associated with the latter was responsible for the superstorm. Two reverse waves were detected, one at the edge and one near the center of the magnetic cloud (MC). It is suspected that these 'waves' were once reverse shocks which were becoming evanescent when they propagated into the low plasma beta MC. The second reverse wave caused a decrease in the southward component of the IMF and initiated the storm recovery phase. It is determined that flares located at large longitudinal distances from the subsolar point were the most likely causes of the first two shocks without associated magnetic clouds. It is thus unlikely that the shocks were 'blast waves' or that magnetic reconnection eroded away the two associated MCs. This interplanetary/solar event is an example of the extremely complex magnetic storms which can occur in the post-solar maximum phase.

  4. Phase transition and vapochromism in molecular assemblies of a polymorphic zinc(II) Schiff-base complex.

    PubMed

    Oliveri, Ivan Pietro; Malandrino, Graziella; Di Bella, Santo

    2014-09-15

    This paper reports for the first time the irreversible thermally induced phase transition, accompanied by color change, and the vapochromic behavior of an amphiphilic, Lewis acidic Zn(II) Schiff-base complex, through detailed X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, and optical absorption studies. The unprecedented irreversible phase transition for such kind of complexes is associated with a thermal, lamellar-to-hexagonal columnar structural transition, which involves a different arrangement of each molecular unit within the assembled structure, H- and J-type aggregates, respectively, responsible for the thermochromic behavior. The vapochromism, investigated either in powder samples or in thermally annealed cast films, is related to the formation of 1:1 adducts upon exposure to vapors of strong Lewis bases and implies dramatic optical absorption variations and naked-eye observation of the change in color from red-brown to red. The chemisorption process is fast, completely reversible, reproducible, and selective for amines. The reversible switching of the chemisorption-desorption process in cast films is demonstrated by successive cycles, amine exposure and subsequent heating, by monitoring the substantial optical absorption changes in the visible region. Vapochromism of this material can potentially be used to detect vapors of volatile amines. PMID:25148651

  5. Direct imaging of complex nano- to microscale interfaces involving solid, liquid, and gas phases.

    PubMed

    Rykaczewski, Konrad; Landin, Trevan; Walker, Marlon L; Scott, John Henry J; Varanasi, Kripa K

    2012-10-23

    Surfaces with special wetting properties not only can efficiently repel or attract liquids such as water and oils but also can prevent formation of biofilms, ice, and clathrate hydrates. Predicting the wetting properties of these special surfaces requires detailed knowledge of the composition and geometry of the interfacial region between the droplet and the underlying substrate. In this work we introduce a 3D quantitative method for direct nanoscale visualization of such interfaces. Specifically, we demonstrate direct nano- to microscale imaging of complex fluidic interfaces using cryostabilization in combination with cryogenic focused ion beam milling and SEM imaging. We show that application of this method yields quantitative information about the interfacial geometry of water condensate on superhydrophilic, superhydrophobic, and lubricant-impregnated surfaces with previously unattainable nanoscale resolution. This type of information is crucial to a fundamental understanding as well as the design of surfaces with special wetting properties. PMID:23020195

  6. Gas-Phase Terahertz Spectroscopy and the Study of Complex Interstellar Chemistry

    NASA Astrophysics Data System (ADS)

    Braakman, Rogier

    2010-11-01

    Terahertz spectroscopy holds great promise in the advancement of the field of astrochemistry. The sensitive observation of interstellar THz radiation is expected to lower detection limits and allow the study of larger and more complex species than is currently possible at millimeter wavelengths, which will place further constraints on chemical models and permit a direct comparison to the organic compounds seen in carbonaceous chondrites. With the successful recent launch of the Herschel Space Telescope, which will give high-fidelity access to interstellar THz radiation for the first time, and the completion of the Atacama Large Millimeter Array (ALMA) by 2013, the THz astronomy era is upon us. Unfortunately, laboratory THz spectroscopy presents significant challenges and will be soon be lagging behind the newly available observational platforms. Technologies to extend the capabilities of high-resolution spectroscopic systems into the THz domain are actively being pursued on many fronts, but affordable systems that are broadly tunable, sensitive and achieve the necessary resolution are not yet available. The work in this thesis should therefore be seen as part of the effort in the transition from centimeter-/millimeter-wave to THz spectroscopy that is currently taking place in the astrochemistry community. As part of this thesis, observational searches for the complex organics hydroxyacetone (CH3COCH2OH), 2-cyanoethanol (OHCH 2CH2CN) and methoxyacetonitrile (CH3OCH2 CN) were attempted at millimeter wavelengths. The unsuccessful nature of these searches highlight the current limits of studying interstellar chemistry using pure rotational spectroscopy. The characterization of the laboratory spectra of these molecules is nonetheless important as it will aid in the assignment and description of the rotational substructure and band shapes of their THz torsional spectra, features that may allow their interstellar detection; and this thesis presents methods by which such

  7. Modeling Three-Phase Compositional Flow on Complex 3D Unstructured Grids with Higher-Order Finite Element Methods

    NASA Astrophysics Data System (ADS)

    Moortgat, J.; Firoozabadi, A.

    2013-12-01

    Most problems of interest in hydrogeology and subsurface energy resources involve complex heterogeneous geological formations. Such domains are most naturally represented in numerical reservoir simulations by unstructured computational grids. Finite element methods are a natural choice to describe fluid flow on unstructured meshes, because the governing equations can be readily discretized for any grid-element geometry. In this work, we consider the challenging problem of fully compositional three-phase flow in 3D unstructured grids, discretized by tetrahedra, prisms, or hexahedra, and compare to simulations on 3D structured grids. We employ a combination of mixed hybrid finite element methods to solve for the pressure and flux fields in a fractional flow formulation, and higher-order discontinuous Galerkin methods for the mass transport equations. These methods are well suited to simulate flow in heterogeneous and fractured reservoirs, because they provide a globally continuous pressure and flux field, while allowing for sharp discontinuities in the phase properties, such as compositions and saturations. The increased accuracy from using higher-order methods improves the modeling of highly non-linear flow, such as gravitational and viscous fingering. We present several numerical examples to study convergence rates and the (lack of) sensitivity to gridding/mesh orientation, and mesh quality. These examples consider gravity depletion, water and gas injection in oil saturated subsurface reservoirs with species exchange between up to three fluid phases. The examples demonstrate the wide applicability of our chosen finite element methods in the study of challenging multiphase flow problems in porous, geometrically complex, subsurface media.

  8. Formation of Complex Organics by Gas Phase and Intracluster Ion-Molecule Reactions Involving Acetylene and Hydrogen Cyanide

    NASA Astrophysics Data System (ADS)

    El-Shall, S.; Hamed, A.; Soliman, A. R.; Momoh, P. O.

    2011-05-01

    Many complex organics including polycyclic aromatic hydrocarbons are present in flames and combustion processes as well as in interstellar clouds and solar nebulae. Here, we present evidence for the formation of complex covalent organics by gas phase and intracluster reactions of the benzene, phenylium, pyridine, pyrimidine, phenylacetylene and benzonitrile cations with acetylene and hydrogen cyanide molecules. These reactions are studied using mass-selected ion mobility, chemical reactivity, collisional dissociation, and ab initio calculations. Measurements of collision cross sections in helium provide structural information on the adducts and allow probing structural changes at different temperatures (isomerization). We observed multiple additions of five acetylene molecules on the pyridine cation at room temperature. This is a remarkable result considering that only two acetylene molecules were added to the phenyl cation and no addition was observed on the benzene cation at room temperature. The experimental results are in full agreement with the ab initio calculations which predict that the first and second acetylenes add to the pyridine ion in barrierless, highly exothermic reactions. Similar reactions have been observed for the pyrimidine radical cation although the extent of the addition reactions is limited to only two acetylene molecules at room temperature. The results provide the first evidence for the incorporation of nitrogen in the formation cyclic hydrocarbons via the gas phase reactions of pyridine and pyrimidine ions with acetylene molecules. In addition, the formation of covalent adducts in the ionized acetylene/HCN system will be reported for the first time. Sequential reactions leading to the formation of pyridine and pyrimidine radical cations and higher adducts are observed over a wide range of temperature and pressure. The formation of these covalent adducts may represent a general class of addition reactions that can form complex

  9. Design Implementation and Testing of a VLSI High Performance ASIC for Extracting the Phase of a Complex Signal

    NASA Astrophysics Data System (ADS)

    Altmeyer, Ronald C.

    2002-09-01

    This thesis documents the research, circuit design, and simulation testing of a VLSI (Very Large Scale Integration) ASIC which extracts phase angle information from a complex sampled signal using the arctangent relationship: (phi=tan/-1 (Q/1). Specifically, the circuit will convert the In-Phase and Quadrature terms into their corresponding phase angle. The design specifications were to implement the design in CMOS (Complementary Metal Oxide Semiconductors) technology with a minimum transistor count and ability to operate at a clock frequency of 700 MHz. Research on the arctangent function was performed to determine mathematical calculation methods and the CORDIC method was chosen to achieve the stated design specifications. MATLAB simulations were used to calculate and verify accuracy and to implement Quine-McClusky logic minimization. T-SPICE netlists were generated and simulations were run to determine transistor and circuit electrical operation and timing. Finally, overall circuit logic functionality of all possible input combinations was completed using a VHDL (VHSIC(Very High Speed Integrated Circuit) Hardware Description Language) simulation program.

  10. Effect of cooling-heating rate on sol-gel transformation of fish gelatin-gum arabic complex coacervate phase.

    PubMed

    Anvari, Mohammad; Chung, Donghwa

    2016-10-01

    The objective of this study was to characterize influence of different cooling and heating rates on gelation of fish gelatin (FG)-gum arabic (GA) complex coacervate phase using rheological measurements. For the coacervate phase prepared at 10°C, the gelling temperature, melting temperature, gel strength, and stress relaxation decreased with increasing cooling or heating rate, however, no gelation was observed at the highest cooling rate of 0.05°C/min. Similar trends were obtained for the coacervates phase prepared at 30°C, but the gelation did not occur at a cooling rate of 0.033 or 0.05°C/min. The results indicated that rheological properties of FG-GA coacervate gels were highly dependent to the cooling process, where more thermos-stable and stronger gels formed at slower cooling. This was probably because of higher degree of molecular rearrangements, more hydrogen bindings, and formation of greater junction zones into the gel network at slower cooling rates. However, all of the FG-GA coacervate gels obtained at different cooling rates were classified as a weak physical gel. PMID:27246375