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Sample records for ii core particles

  1. Nucleosome Core Particle

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Nucleosome Core Particle grown on STS-81. The fundamental structural unit of chromatin and is the basis for organization within the genome by compaction of DNA within the nucleus of the cell and by making selected regions of chromosomes available for transcription and replication. Principal Investigator's are Dr. Dan Carter and Dr. Gerard Bunick of New Century Pharmaceuticals.

  2. Vortex Cores of Inertial Particles.

    PubMed

    Günther, Tobias; Theisel, Holger

    2014-12-01

    The cores of massless, swirling particle motion are an indicator for vortex-like behavior in vector fields and to this end, a number of coreline extractors have been proposed in the literature. Though, many practical applications go beyond the study of the vector field. Instead, engineers seek to understand the behavior of inertial particles moving therein, for instance in sediment transport, helicopter brownout and pulverized coal combustion. In this paper, we present two strategies for the extraction of the corelines that inertial particles swirl around, which depend on particle density, particle diameter, fluid viscosity and gravity. The first is to deduce the local swirling behavior from the autonomous inertial motion ODE, which eventually reduces to a parallel vectors operation. For the second strategy, we use a particle density estimation to locate inertial attractors. With this, we are able to extract the cores of swirling inertial particle motion for both steady and unsteady 3D vector fields. We demonstrate our techniques in a number of benchmark data sets, and elaborate on the relation to traditional massless corelines.

  3. Effective particle magnetic moment of multi-core particles

    NASA Astrophysics Data System (ADS)

    Ahrentorp, Fredrik; Astalan, Andrea; Blomgren, Jakob; Jonasson, Christian; Wetterskog, Erik; Svedlindh, Peter; Lak, Aidin; Ludwig, Frank; van IJzendoorn, Leo J.; Westphal, Fritz; Grüttner, Cordula; Gehrke, Nicole; Gustafsson, Stefan; Olsson, Eva; Johansson, Christer

    2015-04-01

    In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems - BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm.

  4. Improved Thermoplastic/Iron-Particle Transformer Cores

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.; Bryant, Robert G.; Namkung, Min

    2004-01-01

    A method of fabricating improved transformer cores from composites of thermoplastic matrices and iron-particles has been invented. Relative to commercially available laminated-iron-alloy transformer cores, the cores fabricated by this method weigh less and are less expensive. Relative to prior polymer-matrix/ iron-particle composite-material transformer cores, the cores fabricated by this method can be made mechanically stronger and more magnetically permeable. In addition, whereas some prior cores have exhibited significant eddy-current losses, the cores fabricated by this method exhibit very small eddy-current losses. The cores made by this method can be expected to be attractive for use in diverse applications, including high-signal-to-noise transformers, stepping motors, and high-frequency ignition coils. The present method is a product of an experimental study of the relationships among fabrication conditions, final densities of iron particles, and mechanical and electromagnetic properties of fabricated cores. Among the fabrication conditions investigated were molding pressures (83, 104, and 131 MPa), and molding temperatures (250, 300, and 350 C). Each block of core material was made by uniaxial-compression molding, at the applicable pressure/temperature combination, of a mixture of 2 weight percent of LaRC (or equivalent high-temperature soluble thermoplastic adhesive) with 98 weight percent of approximately spherical iron particles having diameters in the micron range. Each molded block was cut into square cross-section rods that were used as core specimens in mechanical and electromagnetic tests. Some of the core specimens were annealed at 900 C and cooled slowly before testing. For comparison, a low-carbon-steel core was also tested. The results of the tests showed that density, hardness, and rupture strength generally increased with molding pressure and temperature, though the correlation was rather weak. The weakness of the correlation was attributed to

  5. Analytical analysis of particle-core dynamics

    SciTech Connect

    Batygin, Yuri K

    2010-01-01

    Particle-core interaction is a well-developed model of halo formation in high-intensity beams. In this paper, we present an analytical solution for averaged, single particle dynamics, around a uniformly charged beam. The problem is analyzed through a sequence of canonical transformations of the Hamiltonian, which describes nonlinear particle oscillations. A closed form expression for maximum particle deviation from the axis is obtained. The results of this study are in good agreement with numerical simulations and with previously obtained data.

  6. Particle Identification at Belle II

    NASA Astrophysics Data System (ADS)

    Sandilya, S.; Belle Collaboration, II

    2016-11-01

    We report on the charged particle identification (PID) systems for the upcoming Belle II experiment. The time of propagation counter in the central region and the proximity focusing ring imaging Cherenkov counters with aerogel radiator in the forward region will be used as the PID devices. They are expected to provide a kaon identification efficiency of more than 94% at a low pion misidentification probability of 4%. The motivation for the upgrade, method and status of both systems are discussed.

  7. Magnetic behavior of core shell particles

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Rong; Wang, Cheng-Chien; Chen, I.-Han

    2006-09-01

    We have prepared composite magnetic core-shell particles using the process of soap-free emulsion polymerization and the co-precipitation method. The shell of the synthesized composite sphere is cobalt ferrite (CoFe 2O 4) nanoparticles and the core consists of poly(styrene-co-methacrylic acid) polymer. The mean crystallite sizes of the coated CoFe 2O 4 nanoparticles were controlled in the range of 2.4-6.7 nm by the concentration of [NH 4+] and heated temperature. The magnetic properties of the core-shell spherical particles can go from superparamagnetic to ferromagnetic behavior depending on the crystalline sizes of CoFe 2O 4.

  8. Purification and crystallization of oxygen-evolving photosystem II core complex from thermophilic cyanobacteria.

    PubMed

    Shen, Jian-Ren; Kawakami, Keisuke; Koike, Hiroyuki

    2011-01-01

    This chapter describes the purification and crystallization of oxygen-evolving photosystem II core dimer complex from a thermophilic cyanobacterium Thermosynechococcus vulcanus. Procedures used for purification of photosystem II from the cyanobacterium involves cultivation of cells, isolation of thylakoid membranes, purification of crude and pure photosystem II core complexes by detergent solubilization, followed by differential centrifugation and column chromatography. The purified core dimer particles were successfully used for crystallization, and the methods and conditions used for crystallization are presented. These purification and crystallization procedures can be applied for another thermophilic cyanobacterium T. elongatus.

  9. Multiscale modelling of nucleosome core particle aggregation

    NASA Astrophysics Data System (ADS)

    Lyubartsev, Alexander P.; Korolev, Nikolay; Fan, Yanping; Nordenskiöld, Lars

    2015-02-01

    The nucleosome core particle (NCP) is the basic building block of chromatin. Under the influence of multivalent cations, isolated mononucleosomes exhibit a rich phase behaviour forming various columnar phases with characteristic NCP-NCP stacking. NCP stacking is also a regular element of chromatin structure in vivo. Understanding the mechanism of nucleosome stacking and the conditions leading to self-assembly of NCPs is still incomplete. Due to the complexity of the system and the need to describe electrostatics properly by including the explicit mobile ions, novel modelling approaches based on coarse-grained (CG) methods at the multiscale level becomes a necessity. In this work we present a multiscale CG computer simulation approach to modelling interactions and self-assembly of solutions of NCPs induced by the presence of multivalent cations. Starting from continuum simulations including explicit three-valent cobalt(III)hexammine (CoHex3+) counterions and 20 NCPs, based on a previously developed advanced CG NCP model with one bead per amino acid and five beads per two DNA base pair unit (Fan et al 2013 PLoS One 8 e54228), we use the inverse Monte Carlo method to calculate effective interaction potentials for a ‘super-CG’ NCP model consisting of seven beads for each NCP. These interaction potentials are used in large-scale simulations of up to 5000 NCPs, modelling self-assembly induced by CoHex3+. The systems of ‘super-CG’ NCPs form a single large cluster of stacked NCPs without long-range order in agreement with experimental data for NCPs precipitated by the three-valent polyamine, spermidine3+.

  10. Entrapment of carbon dioxide with chitosan-based core-shell particles containing changeable cores.

    PubMed

    Dong, Yanrui; Fu, Yinghao; Lin, Xia; Xiao, Congming

    2016-08-01

    Water-soluble chitosan-based core-shell particles that contained changeable cores were successfully applied to anchor carbon dioxide. The entrapment capacity of the particles for carbon dioxide (EC) depended on the cores. It was found that EC of the particles contained aqueous cores was higher than that of the beads with water-soluble chitosan gel cores, which was confirmed with thermogravimetric analysis. In addition, calcium ions and sodium hydroxide were introduced within the particles to examine their effect on the entrapment. EC of the particles was enhanced with sodium hydroxide when the cores were WSC gel. The incorporation of calcium ions was helpful for stabilizing carbon dioxide through the formation of calcium carbonate, which was verified with Fourier transform infrared spectra and scanning electron microscopy/energy-dispersive spectrometry. This phenomenon meant the role of calcium ions for fixating carbon dioxide was significant.

  11. Granulation of core particles suitable for film coating by agitation fluidized bed I. Optimum formulation for core particles and development of a novel friability test method.

    PubMed

    Hamashita, Tomohiro; Nakagawa, Yasuo; Aketo, Takao; Watano, Satoru

    2007-08-01

    To prepare powdered medicines without bitter taste, film coating is required to cover the surface of core particles. In this study, effect of formulation and operating conditions of agitation fluidized bed on the core particle properties was investigated. In order to prevent breakage of the core particles during coating process, which sometimes causes variation of drug dissolution rate, addition of maltose syrup powder during the formulation process of the core particles was investigated. Also, a method for friability test in which the core particles were subjected to strong impact was proposed to evaluate strength of the core particles. The friability of the core particles determined by this test method correlated well with the actual friability of the particles during the coating process. Based on this result, we confirmed this novel friability test method could predict the core particle endurance during the coating process.

  12. Chimeric hepatitis B virus core particles with parts or copies of the hepatitis C virus core protein.

    PubMed Central

    Yoshikawa, A; Tanaka, T; Hoshi, Y; Kato, N; Tachibana, K; Iizuka, H; Machida, A; Okamoto, H; Yamasaki, M; Miyakawa, Y

    1993-01-01

    Either parts or multiple copies of the core gene of hepatitis C virus (HCV) were fused to the 3' terminus of the hepatitis B virus (HBV) core gene with 34 codons removed. As many as four copies of HCV core protein (720 amino acids) were fused to the carboxy terminus of truncated HBV core protein (149 amino acids) without preventing the assembly of HBV core particles. Chimeric core particles were sandwiched between monoclonal antibody to HBV core and that to HCV core, thereby indicating that antigenic determinants of both HBV and HCV cores were accessible on them. Proteolytic digestion deprived chimeric core particles of the antigenicity for the HCV core without affecting that of the HBV core, confirming the surface exposure of HCV core determinants. The density of HCV core determinants on chimeric core particles increased as copies of fused HCV core protein were increased. Hybrid core particles with multiple HCV core determinants would be instrumental as an antigen probe for detecting class-specific antibodies to the HCV core in patients with acute and chronic hepatitis C and for simultaneous detection of antibodies to HBV core and those to HCV core in donated blood. Images PMID:8396669

  13. Modeling the Arm II core in MicroCap IV

    SciTech Connect

    Dalton, A.C.

    1996-11-01

    This paper reports on how an electrical model for the core of the Arm II machine was created and how to use this model. We wanted to get a model for the electrical characteristics of the ARM II core, in order to simulate this machine and to assist in the design of a future machine. We wanted this model to be able to simulate saturation, variable loss, and reset. Using the Hodgdon model and the circuit analysis program MicroCap IV, this was accomplished. This paper is written in such a way as to allow someone not familiar with the project to understand it.

  14. Particle Behavior During the Arc Spraying Process with Cored Wires

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Vogli, E.; Abdulgader, M.; Gurris, M.; Kuzmin, D.; Turek, S.

    2008-12-01

    To use the manifold possibilities that arc spraying offers to deposit wear resistance layers, knowledge of the particle formation and their behavior is necessary. This work is focused on studying the particle properties during arc spraying with cored wires. Different cored wires under various spraying parameters are investigated by means of a high speed camera. Particle properties in-flight, such as velocity and temperature, are determined. Correlation between particle behavior and particle characteristics at different spraying conditions is established. At the same time, the particle-laden gas flow is simulated numerically and the computed solutions are used to illustrate the utility of the proposed CFD model and compared with experimental results. The employed mathematical model represents a system of macroscopic conservation laws for the continuous gas phase and for the gas-solid mixture. This approach formulation makes it possible to circumvent the numerical difficulties associated with the implementation of a (potentially ill-posed) two-fluid model. The discretization in space is performed using a high-resolution finite element scheme based on algebraic flux correction in terms of local characteristic variables. The artificial diffusion operator is constructed on the discrete level and fitted to the local solution behavior using a multidimensional flux limiter of TVD type.

  15. Twist Neutrality and the Diameter of the Nucleosome Core Particle

    NASA Astrophysics Data System (ADS)

    Bohr, Jakob; Olsen, Kasper

    2012-03-01

    The diameter of the nucleosome core particle is the same for all the eukaryotes. Here we discuss the possibility that this selectiveness is consistent with a propensity for twist neutrality, in particular, for the double helical DNA to stay rotationally neutral when strained. Reorganization of DNA cannot be done without some level of temporal tensile stress, and as a consequence chiral molecules, such as helices, will twist under strain. The requirement that the nucleosome, constituting the nucleosome core particle and linker DNA, has a vanishing strain-twist coupling leads to a requirement for the amount of bending. For the diameter of the coiled DNA we obtain the relatively accurate numerical estimate of 2R=82Å.

  16. Flying particle sensors in hollow-core photonic crystal fibre

    NASA Astrophysics Data System (ADS)

    Bykov, D. S.; Schmidt, O. A.; Euser, T. G.; Russell, P. St. J.

    2015-07-01

    Optical fibre sensors make use of diverse physical effects to measure parameters such as strain, temperature and electric field. Here we introduce a new class of reconfigurable fibre sensor, based on a ‘flying-particle’ optically trapped inside a hollow-core photonic crystal fibre and illustrate its use in electric field and temperature sensing with high spatial resolution. The electric field distribution near the surface of a multi-element electrode is measured with a resolution of ∼100 μm by monitoring changes in the transmitted light signal due to the transverse displacement of a charged silica microparticle trapped within the hollow core. Doppler-based velocity measurements are used to map the gas viscosity, and thus the temperature, along a hollow-core photonic crystal fibre. The flying-particle approach represents a new paradigm in fibre sensors, potentially allowing multiple physical quantities to be mapped with high positional accuracy over kilometre-scale distances.

  17. Hollow-Core Photonic Band Gap Fibers for Particle Acceleration

    SciTech Connect

    Noble, Robert J.; Spencer, James E.; Kuhlmey, Boris T.; /Sydney U.

    2011-08-19

    Photonic band gap (PBG) dielectric fibers with hollow cores are being studied both theoretically and experimentally for use as laser driven accelerator structures. The hollow core functions as both a longitudinal waveguide for the transverse-magnetic (TM) accelerating fields and a channel for the charged particles. The dielectric surrounding the core is permeated by a periodic array of smaller holes to confine the mode, forming a photonic crystal fiber in which modes exist in frequency pass-bands, separated by band gaps. The hollow core acts as a defect which breaks the crystal symmetry, and so-called defect, or trapped modes having frequencies in the band gap will only propagate near the defect. We describe the design of 2-D hollow-core PBG fibers to support TM defect modes with high longitudinal fields and high characteristic impedance. Using as-built dimensions of industrially-made fibers, we perform a simulation analysis of the first prototype PBG fibers specifically designed to support speed-of-light TM modes.

  18. Chiral discotic columnar germs of nucleosome core particles.

    PubMed Central

    Livolant, F; Leforestier, A

    2000-01-01

    In concentrated solution and in the presence of high concentrations of monovalent cations, nucleosome core particles order into a discotic columnar mesophase. This phase is limited to finite-sized hexagonal germs that further divide into six coiled branches, following an iterative process. We show how the structure of the germs comes from the competition between hexagonal packing and chirality with a combination of dendritic facetting and double-twist configurations. Geometrical considerations lead us to suspect that the chirality of the eukaryotic chromosomes may originate from the same competition. PMID:10777768

  19. New particle searches at Tevatron (II)

    SciTech Connect

    Kamon, T.; CDF and D0 Collaborations

    1996-05-01

    Various recent results of new particle searches at the Fermilab Tevatron are presented. No evidence is found for supersymmetric particles (chargino, gluino), leptoquark bosons and heavy gauge bosons in {ital p{anti P}} collisions at {radical}s = 1.8 TeV. Excluded mass regions for each particle are determined.

  20. Teaching Elementary Particle Physics, Part II

    ERIC Educational Resources Information Center

    Hobson, Art

    2011-01-01

    In order to explain certain features of radioactive beta decay, Wolfgang Pauli suggested in 1930 that the nucleus emitted, in addition to a beta particle, another particle of an entirely new type. The hypothesized particle, dubbed the neutrino, would not be discovered experimentally for another 25 years. It's not easy to detect neutrinos, because…

  1. Nonthermal nuclear reactions induced by fast α particles in the solar core

    NASA Astrophysics Data System (ADS)

    Voronchev, Victor T.

    2015-02-01

    Nonthermal nuclear effects triggered in the solar carbon-nitrogen-oxygen (CNO) cycle by fast α particles—products of the p p chain reactions—are examined. The main attention is paid to 8.674-MeV α particles generated in the 7Li(p ,α ) α reaction. Nonthermal characteristics of these α particles and their influence on some nuclear processes are determined. It is found that the α -particle effective temperature is at a level of 1.1 MeV and exceeds the solar core temperature by 3 orders of magnitude. These fast particles are able to significantly enhance some endoergic (α ,p ) reactions neglected in standard solar model calculations. In particular, they can substantially affect the balance of the p +17O⇄α +14N reactions due to an appreciable increase of the reverse reaction rate. It is shown that in the region R =0.08 -0.25 R⊙ the reverse α +14N reaction can block the forward p +17O reaction, thus preventing closing of the CNO-II cycle, and increase the 17O abundance by a factor of 2-155 depending on R . This indicates that the fast α particles produced in the p p cycle can distort running of the CNO cycle, making it essentially different in the inner and outer core regions.

  2. Therapeutic activity of modified U1 core spliceosomal particles

    PubMed Central

    Rogalska, Malgorzata Ewa; Tajnik, Mojca; Licastro, Danilo; Bussani, Erica; Camparini, Luca; Mattioli, Chiara; Pagani, Franco

    2016-01-01

    Modified U1 snRNAs bound to intronic sequences downstream of the 5′ splice site correct exon skipping caused by different types of mutations. Here we evaluate the therapeutic activity and structural requirements of these exon-specific U1 snRNA (ExSpeU1) particles. In a severe spinal muscular atrophy, mouse model, ExSpeU1, introduced by germline transgenesis, increases SMN2 exon 7 inclusion, SMN protein production and extends life span. In vitro, RNA mutant analysis and silencing experiments show that while U1A protein is dispensable, the 70K and stem loop IV elements mediate most of the splicing rescue activity through improvement of exon and intron definition. Our findings indicate that precise engineering of the U1 core spliceosomal RNA particle has therapeutic potential in pathologies associated with exon-skipping mutations. PMID:27041075

  3. Core-shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Oka, Chiemi; Ushimaru, Kazunori; Horiishi, Nanao; Tsuge, Takeharu; Kitamoto, Yoshitaka

    2015-05-01

    Core-shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core-shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body.

  4. Chemical physics of DNA packaging in a nucleosome core particle

    NASA Astrophysics Data System (ADS)

    Spakowitz, Andrew; Sudhanshu, Bariz

    2008-03-01

    The fundamental unit of packaged DNA, the nucleosome core particle, contains 146 base pairs of DNA wrapped 1.7 times around a cationic protein complex called the histone octamer. A string of nucleosomes is organized into higher-order structures at several hierarchical levels to form chromatin, a remarkable complex that is compact yet maintains accessibility for gene expression. We develop a theoretical model of the nucleosome core particle in order to extract detailed quantitative information from single-molecule measurements of a single nucleosome under tension. We employ the wormlike chain model to describe the DNA strand as a thermally fluctuating polymer chain. The chain adsorbs on a spool that represents the histone octamer. This model is directly compared to single-molecule experiments conducted in Carlos Bustamante's lab; we find good agreement between our theory and the experimental data. Our model reveals the mechanism that underlies structural transitions that are apparent in the experimental measurements and predicts the conditions where these transitions occur. We proceed to construct a free energy surface to predict the dynamic response in a single-molecule experiment with a time-dependent rate of unwinding the nucleosome. The combination of single-molecule experiments and our theoretical modeling gives detailed information about the specific interactions between DNA and histone proteins.

  5. OBSERVED CORE OF A GRADUAL SOLAR ENERGETIC PARTICLE EVENT

    SciTech Connect

    Kocharov, L.; Valtonen, E.; Reiner, M. J.; Thompson, B. J.; Klassen, A.

    2010-12-20

    Using space-borne particle and EUV detection and radio spectrograms from both ground-based and space-borne instruments, we study the first phase of the major solar energetic particle (SEP) event associated with the western solar flare and fast and wide coronal mass ejection (CME) on 2000 April 4. The SEP event being observed at the magnetic connection to the eruption's center starts with deka-MeV nucl{sup -1} helium- and relativistic electron-rich production from coronal sources identified with the electromagnetic diagnostics and the SEP event modeling. The broadband observations and modeling of the initial phase of the 'well-connected' major SEP event support the idea that acceleration of SEPs starts in the helium-rich plasma of the eruption's core in association with coronal shocks and magnetic reconnections caused by the CME liftoff, and that the coronal component dominates during the first hour of the SEP event considered, not yet being shielded by the CME bow shock in the solar wind. The first phase of the SEP event is followed by a second phase of SEP production associated with a decelerating CME-driven shock wave in the solar wind, which accelerates ions from a distinct, helium-poor seed particle population that may originate from the CME interaction with a coronal streamer.

  6. Teaching Elementary Particle Physics, Part II

    NASA Astrophysics Data System (ADS)

    Hobson, Art

    2011-03-01

    In order to explain certain features of radioactive beta decay, Wolfgang Pauli suggested in 1930 that the nucleus emitted, in addition to a beta particle, another particle of an entirely new type. The hypothesized particle, dubbed the neutrino, would not be discovered experimentally for another 25 years. It's not easy to detect neutrinos, because they respond to neither the EM force nor the strong force. For example, the mean free path (average penetration distance before it interacts) of a typical beta-decay neutrino moving through solid lead is about 1.5 light years! Enrico Fermi argued that neutrinos indicated a new force was at work. During the 1930s, he quickly adapted ideas from the developing new theory of QED to this new force, dubbed the weak force. Fermi's theory was able to predict the half-lives of beta-emitting nuclei and the range of energies of the emitted beta particles.

  7. Naked singularities as particle accelerators. II

    SciTech Connect

    Patil, Mandar; Joshi, Pankaj S.; Malafarina, Daniele

    2011-03-15

    We generalize here our earlier results on particle acceleration by naked singularities. We showed recently [M. Patil and P. S. Joshi, Phys. Rev. D 82, 104049 (2010).] that the naked singularities that form due to the gravitational collapse of massive stars provide a suitable environment where particles could get accelerated and collide at arbitrarily high center-of-mass energies. However, we focused there only on the spherically symmetric gravitational collapse models, which were also assumed to be self-similar. In this paper, we broaden and generalize the result to all gravitational collapse models leading to the formation of a naked singularity as the final state of collapse, evolving from a regular initial data, without making any prior restrictive assumptions about the spacetime symmetries such as above. We show that, when the particles interact and collide near the Cauchy horizon, the energy of collision in the center-of-mass frame will be arbitrarily high, thus offering a window to the Planck scale physics. We also consider the issue of various possible physical mechanisms of generation of such very high-energy particles from the vicinity of naked singularity. We then construct a model of gravitational collapse to a timelike naked singularity to demonstrate the working of these ideas, where the pressure is allowed to be negative, but the energy conditions are respected. We show that a finite amount of mass-energy density has to be necessarily radiated away from the vicinity of the naked singularity as the collapse evolves. Therefore, the nature of naked singularities, both at the classical and quantum level, could play an important role in the process of particle acceleration, explaining the occurrence of highly energetic outgoing particles in the vicinity of the Cauchy horizon that participate in extreme high-energy collisions.

  8. Blm10 facilitates nuclear import of proteasome core particles.

    PubMed

    Weberruss, Marion H; Savulescu, Anca F; Jando, Julia; Bissinger, Thomas; Harel, Amnon; Glickman, Michael H; Enenkel, Cordula

    2013-10-16

    Short-lived proteins are degraded by proteasome complexes, which contain a proteolytic core particle (CP) but differ in the number of regulatory particles (RPs) and activators. A recently described member of conserved proteasome activators is Blm10. Blm10 contains 32 HEAT-like modules and is structurally related to the nuclear import receptor importin/karyopherin β. In proliferating yeast, RP-CP assemblies are primarily nuclear and promote cell division. During quiescence, RP-CP assemblies dissociate and CP and RP are sequestered into motile cytosolic proteasome storage granuli (PSG). Here, we show that CP sequestration into PSG depends on Blm10, whereas RP sequestration into PSG is independent of Blm10. PSG rapidly clear upon the resumption of cell proliferation and proteasomes are relocated into the nucleus. Thereby, Blm10 facilitates nuclear import of CP. Blm10-bound CP serves as an import receptor-cargo complex, as Blm10 mediates the interaction with FG-rich nucleoporins and is dissociated from the CP by Ran-GTP. Thus, Blm10 represents the first CP-dedicated nuclear import receptor in yeast.

  9. The Mathematical Structure of Elementary Particles. II.

    DTIC Science & Technology

    1985-05-01

    Functions, Dover, New York, (1965). (2] Berestetski, V., Lifchitz, E., Pitayevski, L., Th6orie Quantique Relativiste, Physique Thdorique (Landau et Lifchitz...M6canique Quantique , Thgorie Non- Relativiste, Physique Th’orique Tome III, Mir, Moscow (1966). C(lO] Omn~s, R., Introduction to Particle Physics, Wiley

  10. Development of magnetic luminescent core/shell nanocomplex particles with fluorescence using Rhodamine 6G

    SciTech Connect

    Lee, Hee Uk; Song, Yoon Seok; Park, Chulhwan; Kim, Seung Wook

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► A simple method was developed to synthesize Co-B/SiO{sub 2}/dye/SiO{sub 2} composite particles. ► The magnetic particle shows that highly luminescent and core/shell particles are formed. ► Such core/shell particles can be easily suspended in water. ► The magnetic particles could detect fluorescence for the application of biosensor. -- Abstract: A simple and reproducible method was developed to synthesize a novel class of Co-B/SiO{sub 2}/dye/SiO{sub 2} composite core/shell particles. Using a single cobalt core, Rhodamine 6G of organic dye molecules was entrapped in a silica shell, resulting in core/shell particles of ∼200 nm diameter. Analyses using a variety of techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, vibration sample magnetometry, confocal laser scanning microscopy, and fluorescence intensity demonstrated that dye molecules were trapped inside the core/shell particles. A photoluminescence investigation showed that highly luminescent and photostable core/shell particles were formed. Such core/shell particles can be easily suspended in water. The synthesized magnetic particles could be used to detect fluorescence on glass substrate arrays for bioassay and biosensor applications.

  11. Experimental Breeder Reactor II (EBR-II): Instrumentation for core surveillance

    SciTech Connect

    Christensen, L.J.

    1989-01-01

    EBR-II has operated for 25 years in support of several major programs. During this time period, several of the original, non-replaceable, flow sensors, RDT sensors and thermocouples have failed in the primary system. This has led to the development of new sensors and the use of calculated values using computer models of the plant. It is important for the next generation of LMR reactors to minimize or eliminate the use of non-replaceable sensors. EBR-II is perhaps the best modeled reactor in the world, thanks to a dedicated T-H analysis program. The success of this program relied on excellent measurements of temperature and flow in subassemblies in the core. The instrumented subassemblies of the XX series provided that measurement capability. From this test series, EBR-II calculations showed that the core could withstand a loss-of-flow without scram accident and a loss-of-heat sink without scram accident from full reactor power without core damage. From this, reactor designers can now design with confidence, inherently safe reactors. 11 refs., 8 figs.

  12. Assembly mechanisms of specialized core particles of the proteasome.

    PubMed

    Bai, Minghui; Zhao, Xian; Sahara, Kazutaka; Ohte, Yuki; Hirano, Yuko; Kaneko, Takeumi; Yashiroda, Hideki; Murata, Shigeo

    2014-07-16

    The 26S proteasome has a highly complicated structure comprising the 20S core particle (CP) and the 19S regulatory particle (RP). Along with the standard CP in all eukaryotes, vertebrates have two more subtypes of CP called the immunoproteasome and the thymoproteasome. The immunoproteasome has catalytic subunits β1i, β2i, and β5i replacing β1, β2, and β5 and enhances production of major histocompatibility complex I ligands. The thymoproteasome contains thymus-specific subunit β5t in place of β5 or β5i and plays a pivotal role in positive selection of CD8+ T cells. Here we investigate the assembly pathways of the specialized CPs and show that β1i and β2i are incorporated ahead of all the other β-subunits and that both β5i and β5t can be incorporated immediately after the assembly of β3 in the absence of β4, distinct from the assembly of the standard CP in which β-subunits are incorporated in the order of β2, β3, β4, β5, β6, β1, and β7. The propeptide of β5t is a key factor for this earlier incorporation, whereas the body sequence seems to be important for the earlier incorporation of β5i. This unique feature of β5t and β5i may account for preferential assembly of the immunoproteasome and the thymoproteasome over the standard type even when both the standard and specialized subunits are co-expressed.

  13. Experimental Study of Brownian Dynamics of Bent-core Colloidal Particles

    NASA Astrophysics Data System (ADS)

    Fan, Chun-Zhen; Joshi, Bhuwan; Huang, Ji-Ping; Wei, Qi-Huo

    2009-03-01

    Bent-core or banana-shaped molecules exhibit a variety of intriguing liquid crystalline mesophases including nematics and smectic phases. We try to develop suspensions of bent-core shaped colloidal particles to mimic the bent-core liquid crystals. This report will focus on the fabrication of bent-core colloidal particle suspension, and optical microscopic studies of the Brownian dynamics of individual bent-core colloidal particles. The bent-core colloidal particles confined between two glass substrates are observed through dark-field optical microscopy, and their orientation and position are obtained through imaging processing. Results on the translational and rotational Brownian dynamics of these type of particles will be reported.

  14. FINDING THE FIRST COSMIC EXPLOSIONS. II. CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Whalen, Daniel J.; Joggerst, Candace C.; Fryer, Chris L.; Stiavelli, Massimo; Heger, Alexander; Holz, Daniel E.

    2013-05-01

    Understanding the properties of Population III (Pop III) stars is prerequisite to elucidating the nature of primeval galaxies, the chemical enrichment and reionization of the early intergalactic medium, and the origin of supermassive black holes. While the primordial initial mass function (IMF) remains unknown, recent evidence from numerical simulations and stellar archaeology suggests that some Pop III stars may have had lower masses than previously thought, 15-50 M{sub Sun} in addition to 50-500 M{sub Sun }. The detection of Pop III supernovae (SNe) by JWST, WFIRST, or the TMT could directly probe the primordial IMF for the first time. We present numerical simulations of 15-40 M{sub Sun} Pop III core-collapse SNe performed with the Los Alamos radiation hydrodynamics code RAGE. We find that they will be visible in the earliest galaxies out to z {approx} 10-15, tracing their star formation rates and in some cases revealing their positions on the sky. Since the central engines of Pop III and solar-metallicity core-collapse SNe are quite similar, future detection of any Type II SNe by next-generation NIR instruments will in general be limited to this epoch.

  15. Core-shell particles: preparation, fundamentals and applications in high performance liquid chromatography.

    PubMed

    Hayes, Richard; Ahmed, Adham; Edge, Tony; Zhang, Haifei

    2014-08-29

    The challenges in HPLC are fast and efficient separation for a wide range of samples. Fast separation often results in very high operating pressure, which places a huge burden on HPLC instrumentation. In recent years, core-shell silica microspheres (with a solid core and a porous shell, also known as fused-core or superficially porous microspheres) have been widely investigated and used for highly efficient and fast separation with reasonably low pressure for separation of small molecules, large molecules and complex samples. In this review, we firstly show the types of core-shell particles and how they are generally prepared, focusing on the methods used to produce core-shell silica particles for chromatographic applications. The fundamentals are discussed on why core-shell particles can perform better with low back pressure, in terms of van Deemter equation and kinetic plots. The core-shell particles are compared with totally porous silica particles and also monolithic columns. The use of columns packed with core-shell particles in different types of liquid chromatography is then discussed, followed by illustrating example applications of such columns for separation of various types of samples. The review is completed with conclusion and a brief perspective on future development of core-shell particles in chromatography.

  16. SAGE II aerosol validation - Selected altitude measurements, including particle micromeasurements

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Russell, Philip B.; Pueschel, Rudolf F.; Snetsinger, Kenneth G.; Ferry, Guy V.; Livingston, John M.; Rosen, James N.; Osborn, Mary T.; Kritz, Mark A.

    1989-01-01

    The validity of particulate extinction coefficients derived from limb path solar radiance measurements obtained during the Stratospheric Aerosol and Gas Experiment (SAGE) II is tested. The SAGE II measurements are compared with correlative aerosol measurements taken during January 1985, August 1985, and July 1986 with impactors, laser spectrometers, and filter samplers on a U-2 aircraft, an upward pointing lidar on a P-3 aircraft, and balloon-borne optical particle counters. The data for July 29, 1986 are discussed in detail. The aerosol measurements taken on this day at an altitude of 20.5 km produce particulate extinction values which validate the SAGE II values for similar wavelengths.

  17. Silica-silver core-shell particles for antibacterial textile application.

    PubMed

    Nischala, K; Rao, Tata N; Hebalkar, Neha

    2011-01-01

    The silica-silver core-shell particles were synthesized by simple one pot chemical method and were employed on the cotton fabric as an antibacterial agent. Extremely small (1-2 nm) silver nanoparticles were attached on silica core particles of average 270 nm size. The optimum density of the nano silver particles was found which was sufficient to show good antibacterial activity as well as the suppression in their surface plasmon resonance responsible for the colour of the core-shell particle for antibacterial textile application. The change in the density and size of the particles in the shell were monitored and confirmed by direct evidence of their transmission electron micrographs and by studying surface plasmon resonance characteristics. The colony counting method of antibacterial activity testing showed excellent results and even the least silver containing core-shell particles showed 100% activity against bacterial concentration of 10(4) colony counting units (cfu). The bonding between core-shell particles and cotton fabric was examined by X-ray photoelectron spectroscopy. The antibacterial activity test confirmed the firm attachment of core-shell particles to the cotton fabric as a result 10 times washed sample was as good antibacterial as that of unwashed sample. The bacterial growth was inhibited on and beneath the coated fabric, at the same time no zone of inhibition which occurs due to the migration of silver ions into the medium was observed indicating immobilization of silver nanoparticles on silica and core-shell particles on fabric by strong bonding.

  18. Uptake and release of anionic surfactant into and from cationic core-shell microgel particles.

    PubMed

    Bradley, Melanie; Vincent, Brian; Burnett, Gary

    2007-08-28

    Core-shell microgel particles, in the colloidal size range, have been prepared and characterized, where the core and the shell are both copolymers, based on N-isopropylacrylamide, but where the core and shell contain different pH-responsive groups having widely separated acid dissociation constants (pKa). The core contains vinylpyridine (VP), which has a pKa value of 4.92, and the shell contains 2-(dimethylamino)ethyl methacrylate (DMAEM), which has a pKa value of 8.4. The dispersion properties, and the uptake and release of an anionic surfactant, sodium dodecylbenzenesulfonate (SDBS), have been studied for both the core and the core-shell microgel particles as a function of pH changes. Both the core and the core-shell particles have been shown to swell as the pH decreases over the range from 7 to 3. However, despite the large differences in the pKa values of the VP and DMEAM groups, no distinct steps in the swelling ratio-pH curve for the core-shell particles were observed, and it is postulated that the boundary between the core and shell regions may be somewhat extended, rather than sharp. The uptake of the anionic surfactant SDBS has been shown to depend on two distinct attractive interactions between the surfactant molecules and the microgel particles: electrostatic and hydrophobic. A reasonable correlation between the minimum in the particle diameter, for both the core and the core-shell particles, and the point of charge neutralization, in the presence of SDBS, has been established.

  19. Gold nanoparticle localization at the core surface by using thermosensitive core-shell particles as a template.

    PubMed

    Suzuki, Daisuke; Kawaguchi, Haruma

    2005-12-06

    We report novel thermosensitive hybrid core-shell particles via in situ gold nanoparticle formation using thermosensitive core-shell particles as a template. This method for the in situ synthesis of gold nanoparticles with microgel interiors offers the advantage of eliminating or significantly reducing particle aggregation. In addition, by using thermosensitive microgel structures in which the shell has thermosensitive and gel properties in water--whereas the core itself is a water-insoluble polymer--we were able to synthesize the gold nanoparticles only at the surface of the core, which had reactive sites to bind metal ions. After the gold nanoparticles were synthesized, electroless gold plating was carried out to control the thickness of the gold nanoshells. The dispersions of the obtained hybrid particles were characterized by dynamic light scattering and UV-vis absorption spectroscopy, and the dried particles were also observed by electron microscopy. Adaptation of the technique shown here will create a number of applications as optical, electronic, and biomedical functional materials.

  20. A Core-Particle Model for Periodically Focused Ion Beams with Intense Space-Charge

    SciTech Connect

    Lund, S M; Barnard, J J; Bukh, B; Chawla, S R; Chilton, S H

    2006-08-02

    A core-particle model is derived to analyze transverse orbits of test particles evolving in the presence of a core ion beam described by the KV distribution. The core beam has uniform density within an elliptical cross-section and can be applied to model both quadrupole and solenoidal focused beams in periodic or aperiodic lattices. Efficient analytical descriptions of electrostatic space-charge fields external to the beam core are derived to simplify model equations. Image charge effects are analyzed for an elliptical beam centered in a round, conducting pipe to estimate model corrections resulting from image charge nonlinearities. Transformations are employed to remove coherent utter motion associated with oscillations of the ion beam core due to rapidly varying, linear applied focusing forces. Diagnostics for particle trajectories, Poincare phase-space projections, and single-particle emittances based on these transformations better illustrate the effects of nonlinear forces acting on particles evolving outside the core. A numerical code has been written based on this model. Example applications illustrate model characteristics. The core-particle model described has recently been applied to identify physical processes leading to space-charge transport limits for an rms matched beam in a periodic quadrupole focusing channel [Lund and Chawla, Nuc. Instr. and Meth. A 561, 203 (2006)]. Further characteristics of these processes are presented here.

  1. Core-corona PSt/P(BA-AA) composite particles by two-stage emulsion polymerization

    NASA Astrophysics Data System (ADS)

    Xie, Delong; Ren, Xiaolin; Zhang, Xinya; Liao, Shijun

    2016-03-01

    Raspberry-shaped composite particles with polystyrene (PSt) as core and poly(n-butyl acrylate-co-acrylic acid) (P(BA-AA)) as corona were synthesized via emulsion polymerization. The random copolymer, P(BA-AA), was pre-prepared and used as a polymeric surfactant, its emulsifying properties adjusted by changing the mass ratio of BA and AA. The morphology of the resulting core-corona composite particles, P(St/P(BA-AA)), could be regulated and controlled by varying the concentrations of P(BA-AA) or the mass ratio of BA:AA in P(BA-AA). The experimental results indicate that 3.0-6.0 wt% of P(BA-AA) is required to obtain stable composite emulsions, and P(BA-AA) with a mass ratio of BA:AA = 1:2 is able to generate distinct core-corona structures. A mechanism of composite particle formation is proposed based on the high affinity between the PSt core and the hydrophobic segments of P(BA-A). The regular morphology of the colloidal film is expected to facilitate potential application of core-corona particles in the field of light scattering. Furthermore, the diversity of core-corona particles can be expanded by replacing P(BA-AA) corona particles with other amphiphilic particles.

  2. Importin β Can Bind Hepatitis B Virus Core Protein and Empty Core-Like Particles and Induce Structural Changes

    PubMed Central

    Pierson, Elizabeth E.; Keifer, David Z.; Delaleau, Mildred; Gallucci, Lara; Cazenave, Christian; Kann, Michael; Jarrold, Martin F.; Zlotnick, Adam

    2016-01-01

    Hepatitis B virus (HBV) capsids are found in many forms: immature single-stranded RNA-filled cores, single-stranded DNA-filled replication intermediates, mature cores with relaxed circular double-stranded DNA, and empty capsids. A capsid, the protein shell of the core, is a complex of 240 copies of core protein. Mature cores are transported to the nucleus by a complex that includes both importin α and importin β (Impα and Impβ), which bind to the core protein’s C-terminal domains (CTDs). Here we have investigated the interactions of HBV core protein with importins in vitro. Strikingly, empty capsids and free core protein can bind Impβ without Impα. Cryo-EM image reconstructions show that the CTDs, which are located inside the capsid, can extrude through the capsid to be bound by Impβ. Impβ density localized on the capsid exterior near the quasi-sixfold vertices, suggested a maximum of 30 Impβ per capsid. However, examination of complexes using single molecule charge-detection mass spectrometry indicate that some complexes include over 90 Impβ molecules. Cryo-EM of capsids incubated with excess Impβ shows a population of damaged particles and a population of “dark” particles with internal density, suggesting that Impβ is effectively swallowed by the capsids, which implies that the capsids transiently open and close and can be destabilized by Impβ. Though the in vitro complexes with great excess of Impβ are not biological, these results have implications for trafficking of empty capsids and free core protein; activities that affect the basis of chronic HBV infection. PMID:27518410

  3. Binding of ethidium to the nucleosome core particle. 2. Internal and external binding modes

    SciTech Connect

    McMurray, C.T.; Small, E.W.; van Holde, K.E. )

    1991-06-11

    The authors have previously reported that the binding of ethidium bromide to the nucleosome core particle results in a stepwise dissociation of the structure which involves the initial release of one copy each of H2A and H2B. In this report, they have examined the absorbance and fluorescence properties of intercalated and outside bound forms of ethidium bromide. From these properties, they have measured the extent of external, electrostatic binding of the dye versus internal, intercalation binding to the core particle, free from contribution by linker DNA. They have established that dissociation is induced by the intercalation mode of binding to DNA within the core particle DNA, and not by binding to the histones or by nonintercalative binding to DNA. The covalent binding of ({sup 3}H)-8-azidoethidium to the core particle clearly shows that < 1.0 adduct is formed per histone octamer over a wide range of input ratios. Simultaneously, analyses of steady-state fluorescence enhancement and fluorescence lifetime data from bound ethidium complexes demonstrate extensive intercalation binding. Combined analyses from steady-state fluorescence intensity with equilibrium dialysis or fluorescence lifetime data revealed that dissociation began when {approximately}14 ethidium molecules are bound by intercalation to each core particle and < 1.0 nonintercalated ion pair was formed per core particle.

  4. DNA base excision repair of uracil residues in reconstituted nucleosome core particles

    PubMed Central

    Nilsen, Hilde; Lindahl, Tomas; Verreault, Alain

    2002-01-01

    The human base excision repair machinery must locate and repair DNA base damage present in chromatin, of which the nucleosome core particle is the basic repeating unit. Here, we have utilized fragments of the Lytechinus variegatus 5S rRNA gene containing site-specific U:A base pairs to investigate the base excision repair pathway in reconstituted nucleosome core particles in vitro. The human uracil-DNA glycosylases, UNG2 and SMUG1, were able to remove uracil from nucleosomes. Efficiency of uracil excision from nucleosomes was reduced 3- to 9-fold when compared with naked DNA, and was essentially uniform along the length of the DNA substrate irrespective of rotational position on the core particle. Furthermore, we demonstrate that the excision repair pathway of an abasic site can be reconstituted on core particles using the known repair enzymes, AP-endonuclease 1, DNA polymerase β and DNA ligase III. Thus, base excision repair can proceed in nucleosome core particles in vitro, but the repair efficiency is limited by the reduced activity of the uracil-DNA glycosylases and DNA polymerase β on nucleosome cores. PMID:12411511

  5. Self-assembly of nucleocapsid-like particles from recombinant hepatitis C virus core protein.

    PubMed

    Kunkel, M; Lorinczi, M; Rijnbrand, R; Lemon, S M; Watowich, S J

    2001-03-01

    Little is known about the assembly pathway and structure of hepatitis C virus (HCV) since insufficient quantities of purified virus are available for detailed biophysical and structural studies. Here, we show that bacterially expressed HCV core proteins can efficiently self-assemble in vitro into nucleocapsid-like particles. These particles have a regular, spherical morphology with a modal distribution of diameters of approximately 60 nm. Self-assembly of nucleocapsid-like particles requires structured RNA molecules. The 124 N-terminal residues of the core protein are sufficient for self-assembly into nucleocapsid-like particles. Inclusion of the carboxy-terminal domain of the core protein modifies the core assembly pathway such that the resultant particles have an irregular outline. However, these particles are similar in size and shape to those assembled from the 124 N-terminal residues of the core protein. These results provide novel opportunities to delineate protein-protein and protein-RNA interactions critical for HCV assembly, to study the molecular details of HCV assembly, and for performing high-throughput screening of assembly inhibitors.

  6. Photovoltaic Properties of CdSe/CdS and CdS/CdSe Core-Shell Particles Synthesized by Use of Uninterrupted Precipitation Procedures

    NASA Astrophysics Data System (ADS)

    Selene Coria-Monroy, C.; Sotelo-Lerma, M.; Martínez-Alonso, Claudia; Moreno-Romero, Paola M.; Rodríguez-Castañeda, Carlos A.; Corona-Corona, Israel; Hu, Hailin

    2015-10-01

    Cadmium Selenide (CdSe) and cadmium sulfide (CdS) are good electron acceptors for hybrid solar cells. CdSe and CdS nanoparticles can be prepared at low temperatures (60-80°C) from alkaline aqueous solutions of a cadmium salt, sodium citrate, and thiourea, as sulfur source, or sodium selenosulfate, as selenium source. Under the same experimental conditions, the reaction kinetics for CdS were faster than for CdSe. Formation of CdSe/CdS core-shell particles (type I: CdSe as core and CdS as shell) could be achieved by use of an uninterrupted one-step process by setting high and low solution temperatures for the core and shell compounds, respectively. The yield of the CdSe product was higher at a pH 8.5-9.5 whereas that of the CdS product was higher at higher pH (10-11). Therefore, formation of the "inverse" CdS/CdSe structure (type II: CdS as core and CdSe as shell) was possible in a one-step solution process by choosing a high solution pH for the core and a lower pH for the shell. Photoluminescence spectra and electron micrographs confirmed formation of the two types of core-shell particle. The photovoltaic performance of heterojunctions prepared with core-shell particles and poly(3-hexylthiophene) (P3HT), also suggested formation of core-shell particles. Both the photovoltage and photocurrent density of hybrid solar cells depended on the shell compound and not on the core. It was shown that the interface of the heterojunctions plays is important in solar cell applications, and its modification could be realized by incorporating different shell compounds on core particles.

  7. Synthesis and Characterization of Polyvinylpyrrolidone Silica Core-Shell Nanocomposite Particles.

    PubMed

    Chen, Lian-Xi; Li, Jie; Li, Xi; Zhang, Zhong-Min; Jiao, Cai-Bin

    2015-03-01

    In this work, a novel and facile strategy for making a new type of polymer/silica nanocomposte particle was proposed. Colloidally stable polyvinypyrrolidone (PVP)/silica core-shell nanocomposite particles have been successfully synthesized using an azo initiator via seed polymerization of N-vinyl-2-pyrrolidone (NVP) and VFSs (VFSs) that were derived from vinyl triethoxysilane (VTES). It was suggested from the FTIR and TGA analysis that the copolymerization reaction of NVP with VFSs has been thoroughly carried out. In addition, SEM images showed that PVP/silica nanocomposite particles have relatively rough surface due to surface polymerization in comparison with VFSs. Furthermore, TEM results proved that the size of VFSs had considerable effects on the appearance of PVP/silica nanocomposite particles. Generally, it presented that several silica nanoparticle cores with an average size of 78 nm mainly pack together within each nanocomposite particle after seed polymerization. Interestingly, the average shell thickness was 59 nm for most PVP/silica nanocomposite particles with cores about 242 nm. However, when the core size was large enough to about 504 nm, a series of PVP/silica nanocomposite particles with a relative thin shell were observed.

  8. Amino-functionalized core-shell magnetic mesoporous composite microspheres for Pb(II) and Cd(II) removal.

    PubMed

    Tang, Yulin; Liang, Song; Wang, Juntao; Yu, Shuili; Wang, Yilong

    2013-04-01

    Amino-functionalized Fe3O4@mesoporous SiO2 core-shell composite microspheres NH2-MS in created in multiple synthesis steps have been investigated for Pb(II) and Cd(II) adsorption. The microspheres were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), N2 adsorption-desorption, zeta potential measurements and vibrating sample magnetometer. Batch adsorption tests indicated that NH2-MS exhibited higher adsorption affinity toward Pb(II) and Cd(II) than MS did. The Langmuir model could fit the adsorption isotherm very well with maximum adsorption capacity of 128.21 and 51.81 mg/g for Pb(II) and Cd(II), respectively, implying that adsorption processes involved monolayer adsorption. Pb(II) and Cd(II) adsorption could be well described by the pseudo second-order kinetics model, and was found to be strongly dependent on pH and humic acid. The Pb(II)- and Cd(II)-loaded microspheres were effectively desorbed using 0.01 mol/L HCl or EDTA solution. NH2-MS have promise for use as adsorbents in the removal of Pb(II) and Cd(II) in wastewater treatment processes.

  9. Neutronic and thermal-hydraulic analysis of new irradiation channels inside the Moroccan TRIGA Mark II research reactor core.

    PubMed

    Chham, E; El Bardouni, T; Benaalilou, K; Boukhal, H; El Bakkari, B; Boulaich, Y; El Younoussi, C; Nacir, B

    2016-10-01

    This study was conducted to improve the capacity of radioisotope production in the Moroccan TRIGA Mark II research reactor, which is considered as one of the most important applications of research reactors. The aim of this study is to enhance the utilization of TRIGA core in the field of neutron activation and ensure an economic use of the fuel. The main idea was to create an additional irradiation channel (IC) inside the core. For this purpose, three new core configurations are proposed, which differ according to the IC position in the core. Thermal neutron flux distribution and other neutronic safety parameters such as power peaking factors, excess reactivity, and control rods worth reactivity were calculated using the Monte Carlo N-Particle Transport (MCNP) code and neutron cross-section library based on ENDF/B-VII evaluation. The calculated thermal flux in the central thimble (CT) and in the added IC for the reconfigured core is compared with the thermal flux in the CT of the existing core, which is taken as a reference. The results show that all the obtained fluxes in CTs are very close to the reference value, while a remarkable difference is observed between the fluxes in the new ICs and reference. This difference depends on the position of IC in the reactor core. To demonstrate that the Moroccan TRIGA reactor could safely operate at 2MW, with new configurations based on new ICs, different safety-related thermal-hydraulic parameters were investigated. The PARET model was used in this study to verify whether the safety margins are met despite the new modifications of the core. The results show that it is possible to introduce new ICs safely in the reactor core, because the obtained values of the parameters are largely far from compromising the safety of the reactor.

  10. Pre-Stressing Micron-Scale Aluminum Core-Shell Particles to Improve Reactivity

    NASA Astrophysics Data System (ADS)

    Levitas, Valery I.; McCollum, Jena; Pantoya, Michelle

    2015-01-01

    The main direction in increasing reactivity of aluminum (Al) particles for energetic applications is reduction in their size down to nanoscale. However, Al nanoparticles are 30-50 times more expensive than micron scale particles and possess safety and environmental issues. Here, we improved reactivity of Al micron scale particles by synthesizing pre-stressed core-shell structures. Al particles were annealed and quenched to induce compressive stresses in the alumina passivation shell surrounding Al core. This thermal treatment was designed based on predictions of the melt-dispersion mechanism (MDM); a theory describing Al particle reaction under high heating rate. For all anneal treatment temperatures, experimental flame propagation rates for Al combined with nanoscale copper oxide (CuO) are in quantitative agreement with the theoretical predictions based on the MDM. The best treatment increases flame rate by 36% and achieves 68% of that for the best Al nanoparticles.

  11. Pre-Stressing Micron-Scale Aluminum Core-Shell Particles to Improve Reactivity

    PubMed Central

    Levitas, Valery I.; McCollum, Jena; Pantoya, Michelle

    2015-01-01

    The main direction in increasing reactivity of aluminum (Al) particles for energetic applications is reduction in their size down to nanoscale. However, Al nanoparticles are 30–50 times more expensive than micron scale particles and possess safety and environmental issues. Here, we improved reactivity of Al micron scale particles by synthesizing pre-stressed core-shell structures. Al particles were annealed and quenched to induce compressive stresses in the alumina passivation shell surrounding Al core. This thermal treatment was designed based on predictions of the melt-dispersion mechanism (MDM); a theory describing Al particle reaction under high heating rate. For all anneal treatment temperatures, experimental flame propagation rates for Al combined with nanoscale copper oxide (CuO) are in quantitative agreement with the theoretical predictions based on the MDM. The best treatment increases flame rate by 36% and achieves 68% of that for the best Al nanoparticles. PMID:25597747

  12. Kansas Vocational Agriculture Education. Basic Core Curriculum Project, Horticulture II.

    ERIC Educational Resources Information Center

    Albracht, James, Ed.

    This second horticulture guide is one of a set of three designated as the basic core of instruction for horticulture programs in Kansas. Units of instruction are presented in eight sections: (1) Leadership, (2) Supervised Occupational Experience, (3) Plant Propagation, (4) Soil and Plant Growth Media, (5) Fertilizers, (6) Greenhouse, (7) Plant…

  13. [Scattering properties of core-shell structure of mist wrapped dust particles].

    PubMed

    Feng, Shi-qi; Song, Wei; Wang, Yan; Miao, Xin-hui; Xu, Li-jun; Liu, Yu; Li, Cheng; Li Wen-long; Wang, Yi-ran; Cai, Hong-xing

    2014-12-01

    The authors have investigated the optical properties of core-shell structure of mist wrapped dust particles based on the method of discrete dipole approximation (DDA). The influence on the thickness of the elliptical core-shell structure were calculated which the ratio of long axis and short axis is 2:1, and the change of scattering angle for scattering characteristics. The results shows that the thickness of outer layer increase from 1.2 to 4.8 μm with the scattering and extinction coefficient of double core-shell layers particles decrease from 3.4 and 3.43 to 2.543 and 2.545, when the size of inner core isn't change. And scattering relative strength also increased obviously. The thickness of inner core increase from 0.6 to 2.4 μm with the of scattering and extinction coefficient change from 2.59 and 2.88 to 2.6 and 2.76 when thickness of outer remain constant. Effect of the thickness of visible outer layer on the scattering characteristics of double core-shell layers particles is greater, because of the interaction between scattering light and outer materials. The scattering relative intensity decrease with wavelength increased, while increased with the scale of core-shell structure increase. The results make a promotion on the study of the transportation characteristics of laser and scattering characteristics when the atmospheric aerosol and water mist interact together.

  14. [The true story and advantages of the famous Hepatitis B virus core particles: Outlook 2016].

    PubMed

    Pumpens, P; Grens, E

    2016-01-01

    This review article is a continuation of the paper "Hepatitis B core particles as a universal display model: a structure-function basis for development" written by Pumpens P. and Grens E., ordered by Professor Lev Kisselev and published in FEBS Letters, 1999, 442, 1-6. The past 17 years have strengthened the paper's finding that the human hepatitis B virus core protein, along with other Hepadnaviridae family member core proteins, is a mysterious, multifunctional protein. The core gene of the Hepadnaviridae genome encodes five partially collinear proteins. The most important of these is the HBV core protein p21, or HBc. It can self-assemble by forming viral HBc particles, but also plays a crucial role in the regulation of viral replication. Since 1986, the HBc protein has been one of the first and the most successful tools of the virus-like particle (VLP) technology. Later, the woodchuck hepatitis virus core protein (WHc) was also used as a VLP carrier. The Hepadnaviridae core proteins remain favourite VLP candidates for the knowledge-based design of future vaccines, gene therapy vectors, specifically targeted nanocontainers, and other modern nanotechnological tools for prospective medical use.

  15. Importance of core electrostatic properties on the electrophoresis of a soft particle

    NASA Astrophysics Data System (ADS)

    De, Simanta; Bhattacharyya, Somnath; Gopmandal, Partha P.

    2016-08-01

    The impact of the volumetric charged density of the dielectric rigid core on the electrophoresis of a soft particle is analyzed numerically. The volume charge density of the inner core of a soft particle can arise for a dendrimer structure or bacteriophage MS2. We consider the electrokinetic model based on the conservation principles, thus no conditions for Debye length or applied electric field is imposed. The fluid flow equations are coupled with the ion transport equations and the equation for the electric field. The occurrence of the induced nonuniform surface charge density on the outer surface of the inner core leads to a situation different from the existing analysis of a soft particle electrophoresis. The impact of this induced surface charge density together with the double-layer polarization and relaxation due to ion convection and electromigration is analyzed. The dielectric permittivity and the charge density of the core have a significant impact on the particle electrophoresis when the Debye length is in the order of the particle size. We find that by varying the ionic concentration of the electrolyte, the particle can exhibit reversal in its electrophoretic velocity. The role of the polymer layer softness parameter is addressed in the present analysis.

  16. SAGE II aerosol validation: selected altitude measurements, including particle micromeasurements.

    PubMed

    Oberbeck, V R; Livingston, J M; Russell, P B; Pueschel, R F; Rosen, J N; Osborn, M T; Kritz, M A; Snetsinger, K G; Ferry, G V

    1989-06-20

    Correlative aerosol measurements taken at a limited number of altitudes during coordinated field experiments are used to test the validity of particulate extinction coefficients derived from limb path solar radiance measurements taken by the Stratospheric Aerosol and Gas Experiment (SAGE) II Sun photometer. In particular, results are presented from correlative measurement missions that were conducted during January 1985, August 1985, and July 1986. Correlative sensors included impactors, laser spectrometers, and filter samplers aboard an U-2-airplane, an upward pointing lidar aboard a P-3 airplane, and balloon-borne optical particle counters (dustsondes). The main body of this paper focuses on the July 29, 1986, validation experiment, which minimized the many difficulties (e.g., spatial and temporal inhomogeneities, imperfect coincidences) that can complicate the validation process. On this day, correlative aerosol measurements taken at an altitude of 20.5 km agreed with each other within their respective uncertainties, and particulate extinction values calculated at SAGE II wavelengths from these measurements validated corresponding SAGE II values. Additional validation efforts on days when measurement and logistical conditions were much less favorable for validation are discussed in an appendix.

  17. Particle Simulations of DARHT-II Transport System

    SciTech Connect

    Poole, B; Chen, Y J

    2001-06-11

    The DARHT-II beam line utilizes a fast stripline kicker to temporally chop a high current electron beam from a single induction LINAC and deliver multiple temporal electron beam pulses to an x-ray converter target. High beam quality needs to be maintained throughout the transport line from the end of the accelerator through the final focus lens to the x-ray converter target to produce a high quality radiographic image. Issues that will affect beam quality such as spot size and emittance at the converter target include dynamic effects associated with the stripline kicker as well as emittance growth due to the nonlinear forces associated with the kicker and various focusing elements in the transport line. In addition, dynamic effects associated with transverse resistive wall instability as well as gas focusing will affect the beam transport. A particle-in-cell code is utilized to evaluate beam transport in the downstream transport line in DARHT-II. External focusing forces are included utilizing either analytic expressions or field maps. Models for wakefields from the beam kicker, transverse resistive wall instability, and gas focusing are included in the simulation to provide a more complete picture of beam transport in DARHT-II. From these simulations, for various initial beam loads based on expected accelerator performance the temporally integrated target spot size and emittance can be estimated.

  18. Hydrothermal synthesis of high-quality type-II CdTe/CdSe core/shell quantum dots with dark red emission.

    PubMed

    Liu, Ning; Yang, Ping

    2014-08-01

    A hydrothermal method was used to synthesize type-II CdTe/CdSe core/shell quantum dots (QDs) using the thilglycolic acid (TGA) capped CdTe QDs as cores, which show a number of advantages. Because of the spatial separation of carriers the low excited states of CdTe/CdSe QDs, they exhibit many novel properties that are fundamentally different from the type-I QDs. On the other hand, our experiment results show that the wave function of the hole of the exciton in the CdTe core extends well into the CdSe shell. The results also reveal that a thick shell can confine the electrons inside the particles and thereby improve the PL efficiency and prolong the lifetime of the core/shell QDs. We use the UV-vis absorption and fluorescence spectrum measurements on growing particles in detail. We found that the fluorescence of the CdTe/CdSe QDs was strongly dependent on the thick of the shell and size of the core as well as the unique type-II heterostructure, which make the type-II core/shell QDs more suitable in photovoltaic or photoconduction applications.

  19. Nucleation mode particles with a nonvolatile core in the exhaust of a heavy duty diesel vehicle.

    PubMed

    Rönkkö, Topi; Virtanen, Annele; Kannosto, Jonna; Keskinen, Jorma; Lappi, Maija; Pirjola, Liisa

    2007-09-15

    The characteristics of the nucleation mode particles of a Euro IV heavy-duty diesel vehicle exhaust were studied. The NOx and PM emissions of the vehicle were controlled through the use of cooled EGR and high-pressure fuel injection techniques; no exhaust gas after-treatment was used. Particle measurements were performed in vehicle laboratory and on road. Nucleation mode dominated the particle number size distribution in all the tested driving conditions. According to the on-road measurements, the nucleation mode was already formed after 0.7 s residence time in the atmosphere and no significant changes were observed for longer residence times. The nucleation mode was insensitive to the fuel sulfur content, dilution air temperature, and relative humidity. An increase in the dilution ratio decreased the size of the nucleation mode particles. This behavior was observed to be linked to the total hydrocarbon concentration in the diluted sample. In volatility measurements, the nucleation mode particles were observed to have a nonvolatile core with volatile species condensed on it. The results indicate that the nucleation mode particles have a nonvolatile core formed before the dilution process. The core particles have grown because of the condensation of semivolatile material, mainly hydrocarbons, during the dilution.

  20. Coherence in Dense Cores. II. The Transition to Coherence

    NASA Astrophysics Data System (ADS)

    Goodman, Alyssa A.; Barranco, Joseph A.; Wilner, David J.; Heyer, Mark H.

    1998-09-01

    After studying how line width depends on spatial scale in low-mass star-forming regions, we propose that ``dense cores'' (Myers & Benson 1983) represent an inner scale of a self-similar process that characterizes larger scale molecular clouds. In the process of coming to this conclusion, we define four distinct types of line width-size relation (Δv~Rai), which have power-law slopes a1, a2, a3, and a4, as follows: Type 1--multitracer, multicloud intercomparison; Type 2--single-tracer, multicloud intercomparison; Type 3--multitracer study of a single cloud; and Type 4--single-tracer study of a single cloud. Type 1 studies (of which Larson 1981 is the seminal example) are compendia of Type 3 studies which illustrate the range of variation in the line width-size relation from one region to another. Using new measurements of the OH and C18O emission emanating from the environs of several of the dense cores studied in NH3 by Barranco & Goodman (1998; Paper I), we show that line width increases with size outside the cores with a4 ~ 0.2. On scales larger than those traced by C18O or OH, 12CO and 13CO observations indicate that a4 increases to ~0.5 (Heyer & Schloerb 1997). By contrast, within the half-power contour of the NH3 emission from the cores, line width is virtually constant, with a4 ~ 0. We interpret the correlation between increasing density and decreasing Type 4 power-law slope as a ``transition to coherence.'' Our data indicate that the radius Rcoh at which the gas becomes coherent (i.e., a4 --> 0) is of order 0.1 pc in regions forming primarily low-mass stars. The value of the nonthermal line width at which ``coherence'' is established is always less than but still of order of the thermal line width of H2. Thus coherent cores are similar to, but not exactly the same as, isothermal balls of gas. Two other results bolster our proposal that a transition to coherence takes place at ~0.1 pc. First, the OH, C18O, and NH3 maps show that the dependence of column

  1. Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

    DOE PAGES

    Jiang, Xingmao; Jiang, Ying-Bing; Liu, Nanguo; ...

    2011-01-01

    Ceriumore » m (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0 × 10 − 14  m 2 s for Ce 3+ compared to 2.5 × 10 − 13  m 2 s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.« less

  2. Chemical compositions of black carbon particle cores and coatings via soot particle aerosol mass spectrometry with photoionization and electron ionization.

    PubMed

    Canagaratna, Manjula R; Massoli, Paola; Browne, Eleanor C; Franklin, Jonathan P; Wilson, Kevin R; Onasch, Timothy B; Kirchstetter, Thomas W; Fortner, Edward C; Kolb, Charles E; Jayne, John T; Kroll, Jesse H; Worsnop, Douglas R

    2015-05-14

    Black carbon is an important constituent of atmospheric aerosol particle matter (PM) with significant effects on the global radiation budget and on human health. The soot particle aerosol mass spectrometer (SP-AMS) has been developed and deployed for real-time ambient measurements of refractory carbon particles. In the SP-AMS, black carbon or metallic particles are vaporized through absorption of 1064 nm light from a CW Nd:YAG laser. This scheme allows for continuous "soft" vaporization of both core and coating materials. The main focus of this work is to characterize the extent to which this vaporization scheme provides enhanced chemical composition information about aerosol particles. This information is difficult to extract from standard SP-AMS mass spectra because they are complicated by extensive fragmentation from the harsh 70 eV EI ionization scheme that is typically used in these instruments. Thus, in this work synchotron-generated vacuum ultraviolet (VUV) light in the 8-14 eV range is used to measure VUV-SP-AMS spectra with minimal fragmentation. VUV-SP-AMS spectra of commercially available carbon black, fullerene black, and laboratory generated flame soots were obtained. Small carbon cluster cations (C(+)-C5(+)) were found to dominate the VUV-SP-AMS spectra of all the samples, indicating that the corresponding neutral clusters are key products of the SP vaporization process. Intercomparisons of carbon cluster ratios observed in VUV-SP-AMS and SP-AMS spectra are used to confirm spectral features that could be used to distinguish between different types of refractory carbon particles. VUV-SP-AMS spectra of oxidized organic species adsorbed on absorbing cores are also examined and found to display less thermally induced decomposition and fragmentation than spectra obtained with thermal vaporization at 200 °C (the minimum temperature needed to quantitatively vaporize ambient oxidized organic aerosol with a continuously heated surface). The particle cores

  3. Tuning the spin crossover in nano-objects: From hollow to core-shell particles

    NASA Astrophysics Data System (ADS)

    Félix, Gautier; Mikolasek, Mirko; Molnár, Gábor; Nicolazzi, William; Bousseksou, Azzedine

    2014-06-01

    Core-shell nanoparticles displaying spin crossover (SCO) effect on the shell and/or on the core are studied using Monte Carlo simulations of an elastic microscopic Ising-like model. In this Letter we demonstrate that the SCO transition temperature can be controlled by adjusting the width of the shell and the width of the core as well as the misfit between the lattice constants. An original coupled system with a SCO active shell and an active core with another SCO material is proposed. Inducing the transition of the core by the spin transition of the shell results in a hysteresis in the thermal spin transition of the shell. This new type of memory effect in SCO compounds is based on the engineering of particle morphology.

  4. Amplified light scattering and emission of silver and silver core-silica shell particles.

    PubMed

    Siiman, Olavi; Jitianu, Andrei; Bele, Marjan; Grom, Patricia; Matijević, Egon

    2007-05-01

    Side versus forward light scattergrams, and fluorescence (488 nm excitation) intensity versus particle count histograms were gathered for bare, R6G-coated, and silica-R6G-coated silver particles of 150-200 nm diameter, one-by-one by flow cytometry. Fluorescence emission intensity of the composite particles monotonically increased and then reached a plateau with greater R6G concentrations, as measured by flow cytometry. Fluorescence amplification factors of up to 3.5x10(3) were estimated by reference to measurements on core-shell particles with silica instead of silver cores. Huge surface enhanced Raman scattering (SERS) intensities, at least 10(14)-fold greater than normal Raman scattering intensities, were observed with 633 nm excitation for molecules such as rhodamine 6G (R6G) on the same single particles of silver. Although routine transmission (TEM) and scanning (SEM) electron microscopies showed gross structures of the bare and coated particles, high-resolution field emission scanning electron microscopy (FE-SEM), revealed Brownian roughness describing quantum size and larger structures on the surface of primary colloidal silver particles. These silver particles were further characterized by extinction spectra and zeta potentials. Structural and light scattering observations that are reported herein were used to tentatively propose a new hierarchical model for the mechanism of SERS.

  5. Evaluation of storing Shippingport Core II spent blanket fuel assemblies in the T Plant PWR Core II fuel pool without active cooling

    SciTech Connect

    Gilbert, E.R.; Lanning, D.D.; Dana, C.M.; Hedengren, D.C.

    1994-10-01

    PWR Core II fuel pool chiller-off test was conducted because it appeared possible that acceptable pool-water temperatures could be maintained without operating the chillers, thus saving hundreds of thousands of dollars in maintenance and replacement costs. Test results showed that the water-cooling capability is no longer needed to maintain pool temperature below 38{degrees}C (100{degrees}F).

  6. Resonant optical propulsion of a particle inside a hollow-core photonic crystal fiber.

    PubMed

    Maslov, A V

    2016-07-01

    Resonant propulsion of small nonresonant particles inside metal waveguides due to the formation of resonant states by the guided modes below their cutoffs has been predicted in the past. Here it is shown that stable resonant propulsion exists in hollow-core photonic crystal fibers, which are all-dielectric structures and are a major platform for various photonic applications. Specific features of the resonant propulsion are discussed together with the fiber design issues. The results may enable power-efficient transport of particles over long distances, particle sorting, and sensitive detection.

  7. Viscoelastic properties of electrorheological suspensions of core-shell (carbon/polyaniline) particles in silicone oil

    NASA Astrophysics Data System (ADS)

    Sedlacik, M.; Almajdalawi, S.; Mrlik, M.; Pavlinek, V.; Saha, P.; Stejskal, J.

    2013-02-01

    Carbon/polyaniline particles with core-shell structure were synthesized as a novel dispersed phase for electrorheological (ER) suspensions in this study. Core of these composite particles was obtained by carbonization of polyaniline base in an inert atmosphere of nitrogen at 650°C and then coated with polyaniline shell. The morphology and composition of prepared particles were examined with scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. The analysis revealed the conversion of polyaniline to carbon via ring-opening happened during the carbonization process and successful coating of carbonized particles with shell layer. The products retained the original granular structure after carbonization as well as after the coatings. The dielectric spectra analysis suggests high particle polarizability of carbonized material. Thus, the measurements performed under oscillatory shear flow showed a remarkably high ER intensity at relatively low electric field strengths. Coating of carbonized particles by polyaniline base changes compatibility of particle surface with silicone oil medium and, consequently, flow properties of suspensions in the absence of electric field, but does not influence the shear rate dependence of the complex viscosity in the electric field.

  8. Core Fueling and Edge Particle Flux Analysis in Ohmically and Auxiliary Heated NSTX Plasmas

    SciTech Connect

    V.A. Soukhanovskii; R. Maingi; R. Raman; H.W. Kugel; B.P. LeBlanc; L. Roquemore; C.H. Skinner; NSTX Research Team

    2002-06-12

    The Boundary Physics program of the National Spherical Torus Experiment (NSTX) is focusing on optimization of the edge power and particle flows in b * 25% L- and H-mode plasmas of t {approx} 0.8 s duration heated by up to 6 MW of high harmonic fast wave and up to 5 MW of neutral beam injection. Particle balance and core fueling efficiencies of low and high field side gas fueling of L-mode homic and NBI heated plasmas have been compared using an analytical zero dimensional particle balance model and measured ion and neutral fluxes. Gas fueling efficiencies are in the range of 0.05-0.20 and do not depend on discharge magnetic configuration, density or poloidal location of the injector. The particle balance modeling indicates that the addition of HFS fueling results in a reversal of the wall loading rate and higher wall inventories. Initial particle source estimates obtained from neutral pressure and spectroscopic measurements indicate that ion flux into the divertor greatly exceeds midplane ion flux from the main plasma, suggesting that the scrape-off cross-field transport plays a minor role in diverted plasmas. Present analysis provides the basis for detailed fluid modeling of core and edge particle flows and particle confinement properties of NSTX plasmas. This research was supported by the U.S. Department of Energy under contracts No. DE-AC02-76CH03073, DE-AC05-00OR22725, and W-7405-ENG-36.

  9. Biodegradable and magnetic core-shell composite particle prepared by emulsion solvent diffusion method

    NASA Astrophysics Data System (ADS)

    Oka, Chiemi; Ushimaru, Kazunori; Horiishi, Nanao; Tsuge, Takeharu; Kitamoto, Yoshitaka

    2016-02-01

    The present paper describes optimization of preparation conditions of a core-shell composite particle, and its heat generation by alternating magnetic fields. The composite particles are prepared with a modified emulsion solvent diffusion method, which is combined with Pickering emulsion stabilized by magnetic nanoparticles. In this method, the magnetic nanoparticles act as an emulsifier, and its amount and size are crucial to morphology of the composite particles. The magnetic nanoparticles of 8-9 nm would be strongly adsorbed at a liquid-liquid interface rather than the larger nanoparticles. At the optimized concentration of the magnetic nanoparticle’s suspension for the preparation, small and uniform composite particles are obtained since the amount of the nanoparticles is enough to prevent coalescence of droplets during the formation of the composites. The heat generation by alternating magnetic fields emerged certainly. This result suggests the composite particles have a property as a heat-generating carrier for hyperthermia treatment.

  10. Structure of RCC1 chromatin factor bound to the nucleosome core particle

    SciTech Connect

    Makde, Ravindra D.; England, Joseph R.; Yennawar, Hemant P.; Tan, Song

    2010-11-11

    The small GTPase Ran enzyme regulates critical eukaryotic cellular functions including nuclear transport and mitosis through the creation of a RanGTP gradient around the chromosomes. This concentration gradient is created by the chromatin-bound RCC1 (regulator of chromosome condensation) protein, which recruits Ran to nucleosomes and activates Ran's nucleotide exchange activity. Although RCC1 has been shown to bind directly with the nucleosome, the molecular details of this interaction were not known. Here we determine the crystal structure of a complex of Drosophila RCC1 and the nucleosome core particle at 2.9 {angstrom} resolution, providing an atomic view of how a chromatin protein interacts with the histone and DNA components of the nucleosome. Our structure also suggests that the Widom 601 DNA positioning sequence present in the nucleosomes forms a 145-base-pair nucleosome core particle, not the expected canonical 147-base-pair particle.

  11. Interfacial strain effect on type-I and type-II core/shell quantum dots

    NASA Astrophysics Data System (ADS)

    Gheshlaghi, Negar; Pisheh, Hadi Sedaghat; Karim, M. Rezaul; Malkoc, Derya; Ünlü, Hilmi

    2016-09-01

    A comparative experimental and theoretical study on the calculation of capped core diameter in ZnSe/ZnS, CdSe/Cd(Zn)S type-I and ZnSe/CdS type-II core/shell nanocrystals is presented. The lattice mismatch induced interface strain between core and shell was calculated from continuum elastic theory and applied in effective mass approximation method to obtain the corresponding capped core diameter. The calculated results were compared with diameter of bare cores (CdSe and ZnSe) from transmission electron microscopy images to obtain the amount of the stretched or squeezed core after deposition of tensile or compressive shells. The result of the study showed that the core is squeezed in ZnSe/ZnS and CdSe/Cd(Zn)S after compressive shell and stretched in ZnSe/CdS after tensile shell deposition. The stretched and squeezed amount of the capped core found to be in proportion with lattice mismatch amount in the core/shell structure.

  12. Water-soluble core/shell nanoparticles for proton therapy through particle-induced radiation

    NASA Astrophysics Data System (ADS)

    Park, Jeong Chan; Jung, Myung-Hwan; Kim, Maeng Jun; Kim, Kye-Ryung

    2015-02-01

    Metallic nanoparticles have been used in biomedical applications such as magnetic resonance imaging (MRI), therapy, and drug delivery systems. Metallic nanoparticles as therapeutic tools have been demonstrated using radio-frequency magnetic fields or near-infrared light. Recently, therapeutic applications of metallic nanomaterials combined with proton beams have been reported. Particle-induced radiation from metallic nanoparticles, which can enhance the therapeutic effects of proton therapy, was released when the nanoparticles were bombarded by a high-energy proton beam. Core/shell nanoparticles, especially Au-coated magnetic nanoparticles, have drawn attention in biological applications due to their attractive characteristics. However, studies on the phase transfer of organic-ligand-based core/shell nanoparticles into water are limited. Herein, we demonstrated that hydrophobic core/shell structured nanomaterials could be successfully dispersed in water through chloroform/surfactant mixtures. The effects of the core/shell nanomaterials and the proton irradiation on Escherichia coli (E. coli) were also explored.

  13. Synthesis, characterization and application of smart magnetic core-shell polymeric particles

    NASA Astrophysics Data System (ADS)

    Ho, Kin Man Edmond

    Magnetic gamma-Fe2O3 nanoparticles with three different types of surface modification were prepared. They include oleate-coated gamma-Fe 2O3 (o-Fe2O3), citrate-coated gamma-Fe 2O3 (c-Fe2O3), vinyl-coated gamma-Fe 2O3 (MPS-Fe2O3) nanoparticles. These nanoparticles were synthesized via three approaches: (1) decomposition and oxidation of Fe(CO)5 with oleic acid in a hot organic medium; (2) co-precipitation of FeCl2 and FeCl3 in an ammonium solution at pH 11--12, followed by surface coating with trisodium citrate; and (3) subsequent modification of the citrate-coated gamma-Fe2O3 through hydrolysis and condensation of tetraethyl orthosilicate (TEOS) and 3-(trimethoxysilyl)propyl methacrylate (MPS) using the modified Stober method, respectively. Encapsulation of these three types of magnetic nanoparticles into the poly(methyl methacrylate)/chitosan core-shell particles via graft copolymerization of methyl methacrylate (MMA) from chitosan were attempted. Successful encapsulation of iron oxide nanoparticles into the core-shell particles was achieved when the MPS-Fe2O3 nanoparticles were subjected to the copolymerization conditions. The magnetic core-shell particles (MCS) produced, in a reasonable yield, had diameter below 200 nm with narrow size distribution. Transmission electron microscopy (TEM) micrographs of the particles clearly revealed well-defined core-shell nanostructures where magnetic nanoparticles located inside PMMA and coated with chitosan shell. Properties of the MCS particles including their surface charge density, colloidal stability, chemical composition, magnetization measurement and film-forming ability were investigated with zeta-potential measurement, particle size measurement, Fourier-transform infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM) and atomic force microscopy (AFM), respectively. Application of the MCS particles was explored. The MCS particles were used to stabilize with single-walled carbon nanotubes (SWNTs) via

  14. Biosorption of copper(II) and cobalt(II) from aqueous solutions by crab shell particles.

    PubMed

    Vijayaraghavan, K; Palanivelu, K; Velan, M

    2006-08-01

    Biosorption of each of the heavy metals, copper(II) and cobalt(II) by crab shell was investigated in this study. The biosorption capacities of crab shell for copper and cobalt were studied at different particle sizes (0.456-1.117 mm), biosorbent dosages (1-10 g/l), initial metal concentrations (500-2000 mg/l) and solution pH values (3.5-6) in batch mode. At optimum particle size (0.767 mm), biosorbent dosage (5 g/l) and initial solution pH (pH 6); crab shell recorded maximum copper and cobalt uptakes of 243.9 and 322.6 mg/g, respectively, according to Langmuir model. The kinetic data obtained at different initial metal concentrations indicated that biosorption rate was fast and most of the process was completed within 2h, followed by slow attainment of equilibrium. Pseudo-second order model fitted the data well with very high correlation coefficients (>0.998). The presence of light and heavy metal ions influenced the copper and cobalt uptake potential of crab shell. Among several eluting agents, EDTA (pH 3.5, in HCl) performed well and also caused low biosorbent damage. The biosorbent was successfully regenerated and reused for five cycles.

  15. Novel nucleosomal particles containing core histones and linker DNA but no histone H1.

    PubMed

    Cole, Hope A; Cui, Feng; Ocampo, Josefina; Burke, Tara L; Nikitina, Tatiana; Nagarajavel, V; Kotomura, Naoe; Zhurkin, Victor B; Clark, David J

    2016-01-29

    Eukaryotic chromosomal DNA is assembled into regularly spaced nucleosomes, which play a central role in gene regulation by determining accessibility of control regions. The nucleosome contains ∼147 bp of DNA wrapped ∼1.7 times around a central core histone octamer. The linker histone, H1, binds both to the nucleosome, sealing the DNA coils, and to the linker DNA between nucleosomes, directing chromatin folding. Micrococcal nuclease (MNase) digests the linker to yield the chromatosome, containing H1 and ∼160 bp, and then converts it to a core particle, containing ∼147 bp and no H1. Sequencing of nucleosomal DNA obtained after MNase digestion (MNase-seq) generates genome-wide nucleosome maps that are important for understanding gene regulation. We present an improved MNase-seq method involving simultaneous digestion with exonuclease III, which removes linker DNA. Remarkably, we discovered two novel intermediate particles containing 154 or 161 bp, corresponding to 7 bp protruding from one or both sides of the nucleosome core. These particles are detected in yeast lacking H1 and in H1-depleted mouse chromatin. They can be reconstituted in vitro using purified core histones and DNA. We propose that these 'proto-chromatosomes' are fundamental chromatin subunits, which include the H1 binding site and influence nucleosome spacing independently of H1.

  16. Harnessing the advantages of hard and soft colloids by the use of core-shell particles as interfacial stabilizers.

    PubMed

    Buchcic, C; Tromp, R H; Meinders, M B J; Cohen Stuart, M A

    2017-02-15

    The ability of colloidal particles to penetrate fluid interfaces is a crucial factor in the preparation of particle stabilized disperse systems such as foams and emulsions. For hard micron-sized particles the insertion into fluid interfaces requires substantial energy input, but soft particles are known to adsorb spontaneously. Particle hardness, however, may also affect foam and emulsion stability. The high compliance of soft particles may compromise their ability to withstand the lateral compression associated with disproportionation. Hence, particles which can spontaneously adsorb onto fluid interfaces, and yet depict low compliance may be ideal as interfacial stabilizers. In the present work, we prepared core-shell particles comprising a hard, polystyrene core and a soft poly(N-isopropylacrylamide) based shell. We found that such core-shell particles adsorb spontaneously onto various fluid interfaces. The absence of a pronounced energy barrier for interfacial adsorption allowed the facile preparation of particle-stabilized bubbles as well as emulsion droplets. For bubbles, the stability was better than that of bubbles stabilized by entirely soft particles, but disproportionation was not stopped completely. Emulsion droplets, in contrast, showed excellent stability against both coalescence and disproportionation. Lateral compression of core-shell particles due to disproportionation was clearly limited by the presence of the polystyrene core, leading to long-lasting stability. For emulsions, we even observed non-spherical droplets, indicating a negligible Laplace pressure. Our results indicate that core-shell particles comprising a hard core and a soft shell combine the advantageous properties of hard and soft particles, namely spontaneous adsorption and limited compliance, and can therefore be superior materials for the preparation of particle-stabilized dispersions.

  17. LDL particle core enrichment in cholesteryl oleate increases proteoglycan binding and promotes atherosclerosis[S

    PubMed Central

    Melchior, John T.; Sawyer, Janet K.; Kelley, Kathryn L.; Shah, Ramesh; Wilson, Martha D.; Hantgan, Roy R.; Rudel, Lawrence L.

    2013-01-01

    Several studies in humans and animals suggest that LDL particle core enrichment in cholesteryl oleate (CO) is associated with increased atherosclerosis. Diet enrichment with MUFAs enhances LDL CO content. Steroyl O-acyltransferase 2 (SOAT2) is the enzyme that catalyzes the synthesis of much of the CO found in LDL, and gene deletion of SOAT2 minimizes CO in LDL and protects against atherosclerosis. The purpose of this study was to test the hypothesis that the increased atherosclerosis associated with LDL core enrichment in CO results from an increased affinity of the LDL particle for arterial proteoglycans. ApoB-100-only Ldlr−/− mice with and without Soat2 gene deletions were fed diets enriched in either cis-MUFA or n-3 PUFA, and LDL particles were isolated. LDL:proteogylcan binding was measured using surface plasmon resonance. Particles with higher CO content consistently bound with higher affinity to human biglycan and the amount of binding was shown to be proportional to the extent of atherosclerosis of the LDL donor mice. The data strongly support the thesis that atherosclerosis was induced through enhanced proteoglycan binding of LDL resulting from LDL core CO enrichment. PMID:23804810

  18. Toll-like receptor 2 senses hepatitis C virus core protein but not infectious viral particles

    PubMed Central

    Hoffmann, Marco; Zeisel, Mirjam B.; Jilg, Nikolaus; Paranhos-Baccalà, Glaucia; Stoll-Keller, Françoise; Wakita, Takaji; Hafkemeyer, Peter; Blum, Hubert E.; Barth, Heidi; Henneke, Philipp; Baumert, Thomas F.

    2009-01-01

    Toll-like receptors (TLRs) are pathogen recognition molecules activating the innate immune system. Cell surface expressed TLRs, such as TLR2 and TLR4 have been shown to play an important role in human host defenses against viruses through sensing of viral structural proteins. In this study, we aimed to elucidate whether TLR2 and TLR4 participate in inducing antiviral immunity against hepatitis C virus by sensing viral structural proteins. We studied TLR2 and TLR4 activation by cell-culture derived infectious virions (HCVcc) and serum-derived virions in comparison to purified recombinant HCV structural proteins and enveloped virus-like particles. Incubation of TLR2 or TLR4 transfected cell lines with recombinant core protein resulted in activation of TLR2-dependent signaling. In contrast, neither infectious virions nor enveloped HCV-like particles triggered TLR2 and TLR4 signaling. These findings suggest that monomeric HCV core protein but not intact infectious particles are sensed by TLR2. Impairment of core-TLR interaction in infectious viral particles may contribute to escape from innate antiviral immune responses. PMID:20375602

  19. Coherent coexistence of nanodiamonds and carbon onions in icosahedral core-shell particles

    SciTech Connect

    Shevchenko, Vladimir Ya. Madison, Alexey E.; Mackay, Alan L.

    2007-03-01

    In icosahedral carbon nanoparticles, the diamond-like core can undergo a reversible topological transition into and coexist coherently with the onion shells. The general approach for describing and designing complex hierarchical icosahedral structures is discussed. Structural models of icosahedral carbon nanoparticles in which the local arrangement of atoms is virtually identical to that in diamond are derived. It is shown that icosahedral diamond-like particles can be transformed into onion-like shell structures (and vice versa) by the consecutive smoothing (puckering) of atomic networks without disturbance of their topological integrity. The possibility of coherent coexistence of icosahedral diamond-like core with onion shells is shown.

  20. Behavior of pH-sensitive core shell particles at the air-water interface.

    PubMed

    Mathew, Mark D'Souza; Manga, Mohamed S; Hunter, Timothy N; Cayre, Olivier J; Biggs, Simon

    2012-03-20

    In this article, the adsorption of latex core-responsive polymer-shell nanoparticles at the air-water interface is investigated using a Langmuir trough. Phase transition isotherms are used to explore their responsive behavior at the interface as a function of changes in the pH of the subphase. By adjusting the pH of the water prior to particle deposition, we probe the effect of the stabilizing polymer wetting by the water subphase on the stability of these particles at the air-water interface. In addition, by initially compressing a stable film of adsorbed particles and then subsequently changing the pH of the subphase we study desorption of these particles into the water phase.

  1. Protein encapsulated core-shell structured particles prepared by coaxial electrospraying: investigation on material and processing variables.

    PubMed

    Zamani, Maedeh; Prabhakaran, Molamma P; Thian, Eng San; Ramakrishna, Seeram

    2014-10-01

    Biodegradable polymeric particles have been extensively investigated for controlled drug delivery of various therapeutic agents. 'Coaxial' electrospraying was successfully employed in this study, to fabricate core-shell PLGA particles containing bovine serum albumin (BSA) as the model protein, and the results were also compared to particles prepared by 'emulsion' electrospraying. Two different molecular weights of PLGA were employed to encapsulate the protein. Solution properties and processing parameters were found to influence the morphology of the core-shell particles. Depending on the type of solvent used to dissolve the polymer as well as the polymer concentration and molecular weight, the mean diameter of the particles varied between 3.0 to 5.5 μm. Fluorescence microscopic analysis of the electrosprayed particles using FITC-conjugated BSA demonstrated the core-shell structure of the developed particles. The encapsulation efficiency and release behavior of BSA was influenced by shell:core feeding ratio, protein concentration, and the electrospraying method. The encapsulation efficiency of BSA within the core-shell particles of high and low molecular weight PLGA was found 15.7% and 25.1% higher than the emulsion electrosprayed particles, respectively. Moreover, the total amount of BSA released from low molecular weight PLGA particles was significantly higher than high molecular weight PLGA particles within 43 days of release studies, with negligible effect on encapsulation efficiency. The technique of coaxial electrospraying has high potential for encapsulation of susceptible protein-based therapeutic agents such as growth factors for multiple drug delivery applications.

  2. Epoxy-acrylic core-shell particles by seeded emulsion polymerization.

    PubMed

    Chen, Liang; Hong, Liang; Lin, Jui-Ching; Meyers, Greg; Harris, Joseph; Radler, Michael

    2016-07-01

    We developed a novel method for synthesizing epoxy-acrylic hybrid latexes. We first prepared an aqueous dispersion of high molecular weight solid epoxy prepolymers using a mechanical dispersion process at elevated temperatures, and we subsequently used the epoxy dispersion as a seed in the emulsion polymerization of acrylic monomers comprising methyl methacrylate (MMA) and methacrylic acid (MAA). Advanced analytical techniques, such as scanning transmission X-ray microscopy (STXM) and peak force tapping atomic force microscopy (PFT-AFM), have elucidated a unique core-shell morphology of the epoxy-acrylic hybrid particles. Moreover, the formation of the core-shell morphology in the seeded emulsion polymerization process is primarily attributed to kinetic trapping of the acrylic phase at the exterior of the epoxy particles. By this new method, we are able to design the epoxy and acrylic polymers in two separate steps, and we can potentially synthesize epoxy-acrylic hybrid latexes with a broad range of compositions.

  3. Hierarchically functionalized magnetic core/multishell particles and their postsynthetic conversion to polymer capsules.

    PubMed

    Schmitt, Sophia; Silvestre, Martin; Tsotsalas, Manuel; Winkler, Anna-Lena; Shahnas, Artak; Grosjean, Sylvain; Laye, Fabrice; Gliemann, Hartmut; Lahann, Joerg; Bräse, Stefan; Franzreb, Matthias; Wöll, Christof

    2015-01-01

    The controlled synthesis of hierarchically functionalized core/multishell particles is highly desirable for applications in medicine, catalysis, and separation. Here, we describe the synthesis of hierarchically structured metal-organic framework multishells around magnetic core particles (magMOFs) via layer-by-layer (LbL) synthesis. The LbL deposition enables the design of multishell systems, where each MOF shell can be modified to install different functions. Here, we used this approach to create controlled release capsules, in which the inner shell serves as a reservoir and the outer shell serves as a membrane after postsynthetic conversion of the MOF structure to a polymer network. These capsules enable the controlled release of loaded dye molecules, depending on the surrounding media.

  4. Measurement of energetic-particle-driven core magnetic fluctuations and induced fast-ion transport

    NASA Astrophysics Data System (ADS)

    Lin, L.; Ding, W. X.; Brower, D. L.; Koliner, J. J.; Eilerman, S.; Reusch, J. A.; Anderson, J. K.; Nornberg, M. D.; Sarff, J. S.; Waksman, J.; Liu, D.

    2013-03-01

    Internal fluctuations arising from energetic-particle-driven instabilities, including both density and radial magnetic field, are measured in a reversed-field-pinch plasma. The fluctuations peak near the core where fast ions reside and shift outward along the major radius as the instability transits from the n = 5 to n = 4 mode. During this transition, strong nonlinear three-wave interaction among multiple modes accompanied by enhanced fast-ion transport is observed.

  5. Class II 6.7 GHz Methanol Maser Association with Young Massive Cores Revealed by ALMA

    NASA Astrophysics Data System (ADS)

    Chibueze, James O.; Csengeri, Timea; Tatematsu, Ken’ichi; Hasegawa, Tetsuo; Iguchi, Satoru; Alhassan, Jibrin A.; Higuchi, Aya E.; Bontemps, Sylvain; Menten, Karl M.

    2017-02-01

    We explored the implication of the association (or lack of it) of 6.7 GHz class II methanol (CH3OH) masers with massive dense cores (MDCs) detected (within a sample of ATLASGAL selected infrared quiet massive clumps) at 0.9 mm with Atacama Large Millimeter/submillimeter array. We found 42 out of the 112 cores (37.5%) detected with the Atacama Compact Array (ACA) to be associated with 6.7 GHz CH3OH masers. The lowest mass core with CH3OH maser association is ∼ 12 {M}ȯ . The angular offsets of the ACA cores from the 6.7 GHz CH3OH maser peak positions range from 0.″17 to 4.″79, with a median value of 2.″19. We found a weak correlation between the 0.9 mm continuum (MDCs) peak fluxes and the peak fluxes of their associated methanol multibeam (MMB) 6.7 GHz CH3OH masers. About 90% of the cores associated with 6.7 GHz CH3OH masers have masses of >40 M ⊙. The CH3OH maser containing cores are candidates for embedded high-mass protostellar objects in their earliest evolutionary stages. With our ACA 0.9 continuum data compared with the MMB 6.7 GHz CH3OH maser survey, we have constrained the cores already housing massive protostars based on their association with the radiatively pumped 6.7 GHz CH3OH masers.

  6. Low loss Sendust powder cores comprised of particles coated by sodium salt insulating layer

    NASA Astrophysics Data System (ADS)

    Wei, Ding; Wang, Xian; Nie, Yan; Feng, Zekun; Gong, Rongzhou; Chen, Yajie; Harris, V. G.

    2015-05-01

    Toroid-shaped Sendust powder cores were prepared from cold pressing mechanically pulverized Fe-Si-Al powder that had been coated using an inorganic insulating layer. The present work focuses on the effect of the sodium salt-coated Sendust particles upon the high frequency magnetic properties. Sendust powders, having a particle size range of ˜125 μm, exhibit a high saturation magnetization of 118.9 A.m2/kg and a low coercivity of 56 A/m. The experiments indicate that the sodium-based glass insulating layer synthesized from sodium metaphosphate and sodium metaborate can effectively reduce the change in permeability with frequency or DC bias field, yielding high effective permeability (μe) of ˜113 over a wide frequency range from 10 kHz-1 MHz. Furthermore, the effective permeability is measured at ˜27 at H = 7854 A/m, indicating stable and high effective permeability under a DC bias field. The measurements of permeability under DC bias field indicate a peak in the quality factor (Q) values corresponding to a DC-bias field of 1.5-6 (kA/m) at frequencies from 50 to 200 kHz: The effective permeability remains at ˜74. The sodium salt-coated granular cores demonstrate a core loss of 68 mW/cm3 at Bm = 50 mT and f = 50 kHz: These values compare favorably to those of silicone coated Sendust particles.

  7. Synthesis of zirconium tungstate-zirconia core-shell composite particles

    SciTech Connect

    Khazeni, Nasser; Mavis, Bora; Guenduez, Guengoer; Colak, Uner

    2011-11-15

    Highlights: {yields} ZrW{sub 2}O{sub 8}-ZrO{sub 2} core-shell particles to offer solutions for sintering problems. {yields} Core synthesis by a precursor based on tungstic acid and zirconium acetate. {yields} Shell phase by urea hydrolysis in the presence of zirconium ions. {yields} [Urea]/[ZrOCl{sub 2}] ratio controls the rate of shell precursor precipitation. -- Abstract: In this work, ZrW{sub 2}O{sub 8}-ZrO{sub 2} core-shell composite particles were synthesized. ZrW{sub 2}O{sub 8} that was used in the core is a material with negative coefficient of thermal expansion, and it was synthesized from a high-pH precursor based on use of tungstic acid and zirconium acetate. Shell layer was composed of ZrO{sub 2} nanocrystallites and precipitated from an aqueous solution by urea hydrolysis. While volume of the shell was effectively controlled by the initial zirconium ion concentration in the solutions, the rate of precipitation was a function of the ratio of initial concentrations of urea to zirconium ions. It is hypothesized that isolation of the ZrW{sub 2}O{sub 8} within a layer of ZrO{sub 2}, will be a key element in solving problems associated with reactivity of ZrW{sub 2}O{sub 8} towards other components in sintering of ceramic-ceramic composites with tuned or zero thermal expansion coefficient.

  8. EFFECTS OF TUMORS ON INHALED PHARMACOLOGIC DRUGS: II. PARTICLE MOTION

    EPA Science Inventory

    ABSTRACT

    Computer simulations were conducted to describe drug particle motion in human lung bifurcations with tumors. The computations used FIDAP with a Cray T90 supercomputer. The objective was to better understand particle behavior as affected by particle characteristics...

  9. Comparison of Magnesium II Core-to-Wing Ratio Measurements During Solar Minimum 23/24

    NASA Astrophysics Data System (ADS)

    Machol, J. L.; Snow, M. A.; Viereck, R. A.; Weber, M.; Richard, E. C.; Puga, L. C.

    2013-12-01

    Solar extreme ultraviolet (EUV) radiation is the primary energy source to the Earth's upper atmosphere; it heats the thermosphere, creates the ionosphere, and drives photochemistry. A useful proxy for EUV irradiance is the Magnesium II Core-to-Wing Ratio (Mg II index) which is calculated from solar irradiance measurements near 280 nm. This poster compares different satellite measurements of the Mg II index made during the recent solar minimum. We also contrast the indices calculated from high spectral resolution data with indices derived with the classic calculation and 1.1 nm resolution data. These results will be combined with prior Mg II composite time series to create a composite that best represents solar activity over the spacecraft era - 35 years and counting.

  10. On the optimization of the solid core radius of superficially porous particles for finite adsorption rate.

    PubMed

    Kaczmarski, Krzysztof

    2011-02-18

    Packed chromatographic columns with the superficially porous particles (porous shell particles) guarantee higher efficiency. The theoretical equation of the Height Equivalent to a Theoretical Plate (HETP), for columns packed with spherical superficially porous particles, was used for the analysis of the column efficiency for finite rate of adsorption-desorption process. The HETP equation was calculated by the application of the moment analysis to elution peaks evaluated with the General Rate (GR) model. The optimal solid core radius for maximum column efficiency was estimated for a wide spectrum of internal and external mass transfer resistances, adsorption kinetic rate and axial dispersion. The separation power of the shell adsorbent for two component mixture, in analytical and preparative chromatography, was discussed. The conditions of the equivalence between the solutions of the General Rate model with slow adsorption kinetic and the Lumped Kinetic Model (LKM) or the Equilibrium Dispersive (ED) model were formulated.

  11. Architecture of the RNA polymerase II-Mediator core initiation complex.

    PubMed

    Plaschka, C; Larivière, L; Wenzeck, L; Seizl, M; Hemann, M; Tegunov, D; Petrotchenko, E V; Borchers, C H; Baumeister, W; Herzog, F; Villa, E; Cramer, P

    2015-02-19

    The conserved co-activator complex Mediator enables regulated transcription initiation by RNA polymerase (Pol) II. Here we reconstitute an active 15-subunit core Mediator (cMed) comprising all essential Mediator subunits from Saccharomyces cerevisiae. The cryo-electron microscopic structure of cMed bound to a core initiation complex was determined at 9.7 Å resolution. cMed binds Pol II around the Rpb4-Rpb7 stalk near the carboxy-terminal domain (CTD). The Mediator head module binds the Pol II dock and the TFIIB ribbon and stabilizes the initiation complex. The Mediator middle module extends to the Pol II foot with a 'plank' that may influence polymerase conformation. The Mediator subunit Med14 forms a 'beam' between the head and middle modules and connects to the tail module that is predicted to bind transcription activators located on upstream DNA. The Mediator 'arm' and 'hook' domains contribute to a 'cradle' that may position the CTD and TFIIH kinase to stimulate Pol II phosphorylation.

  12. The core collapse supernova rate from the SDSS-II supernova survey

    SciTech Connect

    Taylor, Matt; Cinabro, David; Dilday, Ben; Galbany, Lluis; Gupta, Ravi R.; Kessler, R.; Marriner, John; Nichol, Robert C.; Richmond, Michael; Schneider, Donald P.; Sollerman, Jesper

    2014-09-10

    We use the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SNS) data to measure the volumetric core collapse supernova (CCSN) rate in the redshift range (0.03 < z < 0.09). Using a sample of 89 CCSN, we find a volume-averaged rate of 1.06 ± 0.19 × 10{sup –4}((h/0.7){sup 3}/(yr Mpc{sup 3})) at a mean redshift of 0.072 ± 0.009. We measure the CCSN luminosity function from the data and consider the implications on the star formation history.

  13. The Core Collapse Supernova Rate from the SDSS-II Supernova Survey

    SciTech Connect

    Taylor, Matt; Cinabro, David; Dilday, Ben; Galbany, Lluis; Gupta, Ravi R.; Kessler, R.; Marriner, John; Nichol, Robert C.; Richmond, Michael; Schneider, Donald P.; Sollerman, Jesper

    2014-08-26

    We use the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SNS) data to measure the volumetric core collapse supernova (CCSN) rate in the redshift range (0.03 < z < 0.09). Using a sample of 89 CCSN, we find a volume-averaged rate of 1.06 ± 0.19 × 10(–)(4)((h/0.7)(3)/(yr Mpc(3))) at a mean redshift of 0.072 ± 0.009. We measure the CCSN luminosity function from the data and consider the implications on the star formation history.

  14. Luminescent liquid crystalline materials based on palladium(II) imine derivatives containing the 2-phenylpyridine core.

    PubMed

    Micutz, Marin; Iliş, Monica; Staicu, Teodora; Dumitraşcu, Florea; Pasuk, Iuliana; Molard, Yann; Roisnel, Thierry; Cîrcu, Viorel

    2014-01-21

    In this work we report our studies concerning the synthesis and characterisation of a series of imine derivatives that incorporate the 2-phenylpyridine (2-ppy) core. These derivatives were used in the cyclometalating reactions of platinum(II) or palladium(II) in order to prepare several complexes with liquid crystalline properties. Depending on the starting materials used as well as the solvents employed, different metal complexes were obtained, some of them showing both liquid crystalline behaviour and luminescence properties at room temperature. It was found that, even if there are two competing coordination sites, the cyclometalation process takes place always at the 2-ppy core with (for Pt) or without (for Pd) the imine bond cleavage. We successfully showed that it is possible to prepare emissive room temperature liquid crystalline materials based on double cyclopalladated heteroleptic complexes by varying the volume fraction of the long flexible alkyl tails on the ancillary benzoylthiourea (BTU) ligands.

  15. DNase II digestion of the nucleosome core: precise locations and relative exposures of sites.

    PubMed

    Lutter, L C

    1981-09-11

    The precise locations and relative exposures of the DNase II-accessible sites in the nucleosome core DNA are determined using techniques previously employed for the enzyme DNase I. It is found that there are a number of similarities between the site exposure patterns for the two enzymes but that in general the DNase II seems to discriminate less among adjacent sites' accessibilities than does DNase I. The two enzymes attack essentially the same positions in the DNA, the average difference between the precise location of the site being less than one-half base for the two enzymes. Such close similarities in the digestion patterns of two enzymes with such different mechanisms of scission show that the patterns reflect the structure of the nucleosome core and not merely the properties of the particular enzyme used.

  16. Mesoporous silica coated silica-titania spherical particles: from impregnation to core-shell formation.

    PubMed

    Shiba, Kota; Takei, Toshiaki; Ogawa, Makoto

    2016-11-22

    The coating of solid surfaces with inorganic materials is a promising approach not only to impart various functionalities but also to modify physicochemical properties that are affected by the geometry/structure of the coating. In this study, a silica-hexadecyltrimethylammonium (silica-CTA) hybrid layer was deposited on monodispersed spherical particles composed of titania and octadecylamine (titania-ODA) by a sol-gel reaction of tetraethoxysilane in aqueous CTA/ammonia/methanol solution. The formation of the coating was confirmed by SEM and TEM observations. The coating thickness varied from a few nm to 100 nm depending on the Si/Ti ratio. We found that Si/Ti = 0.68 resulted in the formation of microporous silica-titania particles with the pore size of 0.7 nm as revealed by nitrogen adsorption/desorption measurements. Because the titania-ODA particles can be converted to mesoporous titania particles after removing ODA by acid/base treatment, the silica species can be impregnated into the titania particles and replace ODA under basic conditions. By increasing the Si/Ti molar ratio up to 1.4, silica-titania particles with non-porous structures were obtained. An amorphous to anatase transition occurred at around 800 °C, indicating the complete impregnation of silica inside the titania particles. Further increases of the Si/Ti molar ratio (to 3.4 and 6.8) led to the formation of the silica-CTA shell on the core particles, and the shell was converted to mesoporous silica layers with a pore size of 2 nm after calcination at 550 °C for 5 h. Non-linear control of the pore size/structure is presented for the first time; this will be useful for the precise design of diverse hybrid materials for optical, catalytic and biomedical applications.

  17. Isostructural solid-solid phase transition in monolayers of soft core-shell particles at fluid interfaces: structure and mechanics.

    PubMed

    Rey, Marcel; Fernández-Rodríguez, Miguel Ángel; Steinacher, Mathias; Scheidegger, Laura; Geisel, Karen; Richtering, Walter; Squires, Todd M; Isa, Lucio

    2016-04-21

    We have studied the complete two-dimensional phase diagram of a core-shell microgel-laden fluid interface by synchronizing its compression with the deposition of the interfacial monolayer. Applying a new protocol, different positions on the substrate correspond to different values of the monolayer surface pressure and specific area. Analyzing the microstructure of the deposited monolayers, we discovered an isostructural solid-solid phase transition between two crystalline phases with the same hexagonal symmetry, but with two different lattice constants. The two phases corresponded to shell-shell and core-core inter-particle contacts, respectively; with increasing surface pressure the former mechanically failed enabling the particle cores to come into contact. In the phase-transition region, clusters of particles in core-core contacts nucleate, melting the surrounding shell-shell crystal, until the whole monolayer moves into the second phase. We furthermore measured the interfacial rheology of the monolayers as a function of the surface pressure using an interfacial microdisk rheometer. The interfaces always showed a strong elastic response, with a dip in the shear elastic modulus in correspondence with the melting of the shell-shell phase, followed by a steep increase upon the formation of a percolating network of the core-core contacts. These results demonstrate that the core-shell nature of the particles leads to a rich mechanical and structural behavior that can be externally tuned by compressing the interface, indicating new routes for applications, e.g. in surface patterning or emulsion stabilization.

  18. Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering

    NASA Astrophysics Data System (ADS)

    Çınar, Simge; Tevis, Ian D.; Chen, Jiahao; Thuo, Martin

    2016-02-01

    Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate (‘/’ = physisorbed, ‘-’ = chemisorbed), from molten Field’s metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity.

  19. Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering.

    PubMed

    Çınar, Simge; Tevis, Ian D; Chen, Jiahao; Thuo, Martin

    2016-02-23

    Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate ('/' = physisorbed, '-' = chemisorbed), from molten Field's metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity.

  20. Core/shell silicon/polyaniline particles via in-flight plasma-induced polymerization

    NASA Astrophysics Data System (ADS)

    Yasar-Inceoglu, Ozgul; Zhong, Lanlan; Mangolini, Lorenzo

    2015-08-01

    Although silicon nanoparticles have potential applications in many relevant fields, there is often the need for post-processing steps to tune the property of the nanomaterial and to optimize it for targeted applications. In particular surface modification is generally necessary to both tune dispersibility of the particles in desired solvents to achieve optimal coating conditions, and to interface the particles with other materials to realize functional heterostructures. In this contribution we discuss the realization of core/shell silicon/polymer nanoparticles realized using a plasma-initiated in-flight polymerization process. Silicon particles are produced in a non-thermal plasma reactor using silane as a precursor. After synthesis they are aerodynamically injected into a second plasma reactor into which aniline vapor is introduced. The second plasma initiates the polymerization reactor leading to the formation of a 3-4 nm thick polymer shell surrounding the silicon core. The role of processing conditions on the properties of the polymeric shell is discussed. Preliminary results on the testing of this material as an anode for lithium ion batteries are presented.

  1. Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering

    PubMed Central

    Çınar, Simge; Tevis, Ian D.; Chen, Jiahao; Thuo, Martin

    2016-01-01

    Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate (‘/’ = physisorbed, ‘-’ = chemisorbed), from molten Field’s metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity. PMID:26902483

  2. A Bioinspired Molecular Polyoxometalate Catalyst with Two Cobalt(II) Oxide Cores for Photocatalytic Water Oxidation.

    PubMed

    Wei, Jie; Feng, Yingying; Zhou, Panpan; Liu, Yan; Xu, Jingyin; Xiang, Rui; Ding, Yong; Zhao, Chongchao; Fan, Linyuan; Hu, Changwen

    2015-08-24

    To overcome the bottleneck of water splitting, the exploration of efficient, selective, and stable water oxidation catalysts (WOCs) is crucial. We report an all-inorganic, oxidatively and hydrolytically stable WOC based on a polyoxometalate [(A-α-SiW9 O34)2Co8(OH)6(H2O)2(CO3)3](16-) (Co8 POM). As a cobalt(II)-based cubane water oxidation catalyst, Co8POM embeds double Co(II)4O3 cores. The self-assembled catalyst is similar to the oxygen evolving complex (OEC) of photosystem II (PS II). Using [Ru(bpy)3](2+) as a photosensitizer and persulfate as a sacrificial electron acceptor, Co8POM exhibits excellent water oxidation activity with a turnover number (TON) of 1436, currently the highest among bioinspired catalysts with a cubical core, and a high initial turnover frequency (TOF). Investigation by several spectroscopy, spectrometry, and other techniques confirm that Co8POM is a stable and efficient catalyst for visible light-driven water oxidation. The results offer a useful insight into the design of water oxidation catalysts.

  3. North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part I: Mean states

    NASA Astrophysics Data System (ADS)

    Danabasoglu, Gokhan; Yeager, Steve G.; Bailey, David; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Böning, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Farneti, Riccardo; Fernandez, Elodie; Fogli, Pier Giuseppe; Forget, Gael; Fujii, Yosuke; Griffies, Stephen M.; Gusev, Anatoly; Heimbach, Patrick; Howard, Armando; Jung, Thomas; Kelley, Maxwell; Large, William G.; Leboissetier, Anthony; Lu, Jianhua; Madec, Gurvan; Marsland, Simon J.; Masina, Simona; Navarra, Antonio; George Nurser, A. J.; Pirani, Anna; y Mélia, David Salas; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Treguier, Anne-Marie; Tsujino, Hiroyuki; Uotila, Petteri; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang

    2014-01-01

    Simulation characteristics from eighteen global ocean-sea-ice coupled models are presented with a focus on the mean Atlantic meridional overturning circulation (AMOC) and other related fields in the North Atlantic. These experiments use inter-annually varying atmospheric forcing data sets for the 60-year period from 1948 to 2007 and are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The protocol for conducting such CORE-II experiments is summarized. Despite using the same atmospheric forcing, the solutions show significant differences. As most models also differ from available observations, biases in the Labrador Sea region in upper-ocean potential temperature and salinity distributions, mixed layer depths, and sea-ice cover are identified as contributors to differences in AMOC. These differences in the solutions do not suggest an obvious grouping of the models based on their ocean model lineage, their vertical coordinate representations, or surface salinity restoring strengths. Thus, the solution differences among the models are attributed primarily to use of different subgrid scale parameterizations and parameter choices as well as to differences in vertical and horizontal grid resolutions in the ocean models. Use of a wide variety of sea-ice models with diverse snow and sea-ice albedo treatments also contributes to these differences. Based on the diagnostics considered, the majority of the models appear suitable for use in studies involving the North Atlantic, but some models require dedicated development effort.

  4. Spin control in ladderlike hexanuclear copper(II) complexes with metallacyclophane cores.

    PubMed

    Pardo, Emilio; Bernot, Kevin; Julve, Miguel; Lloret, Francesc; Cano, Joan; Ruiz-García, Rafael; Delgado, Fernando S; Ruiz-Pérez, Catalina; Ottenwaelder, Xavier; Journaux, Yves

    2004-05-03

    Two new hexanuclear oxamatocopper(II) complexes 3 and 4 have been synthesized from the binuclear copper(II) complexes of the meta- and para-phenylenebis(oxamate) ligands, respectively. Complexes 3 and 4 possess an overall ladderlike structure made up of two oxamate-bridged linear trinuclear units ("rails") connected through two phenylenediamidate bridges ("rungs") between the central copper atoms to give metallacyclic cores of the meta- and para-cyclophane type, respectively. They show different ground spin states, S = 1 (3) or S = 0 (4), depending on the substitution pattern in the aromatic spacers. The triplet state molecule 3 containing two spin doublet Cu(II)3 units connected by two m-phenylenediamidate bridges represents a successful extension of the concept of "ferromagnetic coupling units" to metal complexes, which is a well-known approach toward high spin organic radicals.

  5. On the association between core-collapse supernovae and H ii regions

    NASA Astrophysics Data System (ADS)

    Crowther, Paul A.

    2013-01-01

    Previous studies of the location of core-collapse supernovae (ccSNe) in their host galaxies have variously claimed an association with H ii regions; no association or an association only with hydrogen-deficient ccSNe. Here, we examine the immediate environments of 39 ccSNe whose positions are well known in nearby (≤15 Mpc), low-inclination (≤65°) hosts using mostly archival, continuum-subtracted Hα ground-based imaging. We find that 11 out of 29 hydrogen-rich ccSNe are spatially associated with H ii regions (38 ± 11 per cent), versus 7 out of 10 hydrogen-poor ccSNe (70 ± 26 per cent). Similar results from Anderson et al. led to an interpretation that the progenitors of Type Ib/c ccSNe are more massive than those of Type II ccSNe. Here, we quantify the luminosities of H ii region either coincident with or nearby to the ccSNe. Characteristic nebulae are long-lived (˜20 Myr) giant H ii regions rather than short-lived (˜4 Myr) isolated, compact H ii regions. Therefore, the absence of an H ii region from most Type II ccSNe merely reflects the longer lifetime of stars with ⪉12 M⊙ than giant H ii regions. Conversely, the association of an H ii region with most Type Ib/c ccSNe is due to the shorter lifetime of stars with >12 M⊙ stars than the duty cycle of giant H ii regions. Therefore, we conclude that the observed association between certain ccSNe and H ii provides only weak constraints upon their progenitor masses. Nevertheless, we do favour lower mass progenitors for two Type Ib/c ccSNe that lack associated nebular emission, a host cluster or a nearby giant H ii region. Finally, we also reconsider the association between long gamma-ray bursts and the peak continuum light from their (mostly) dwarf hosts, and conclude that this is suggestive of very high mass progenitors, in common with previous studies.

  6. [Adsorption of acid orange II from aqueous solution onto modified peat-resin particles].

    PubMed

    Sun, Qing-Ye; Yang, Lin-Zhang

    2007-06-01

    The adsorption of acid orange II onto modified peat-resin particles was examined in aqueous solution in a batch system. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. The pseudo-first-order, pseudo-second-order kinetic and the intraparticle diffusion models were used to describe the kinetic data. The results showed that both Langmuir and Freundlich adsorption models could be used to describe the adsorption of acid orange II onto modified peat-resin particles. The maximum adsorption capacity was 71.43 mg x g(-1). The data analysis indicated that the intraparticle diffusion model could fit the results of kinetic experiment well. The adsorption rate of acid orange II onto modified peat-resin particles is affected by the initial dye concentrations, sizes and doses of modified peat-resin particles and agitation rates. The surface of modified peat-resin particle is the major adsorption area.

  7. Electronic excitation transport in core antennae of enriched photosystem I particles from spinach chloroplasts

    SciTech Connect

    Causgrove, T.P.; Yang, S.; Struve, W.S.

    1988-10-20

    The polarized photobleaching recovery of PSI-60 particles enriched in iron-sulfur protein and P700 was monitored with approx. 2-ps resolution at 665, 670, 675, and 681 nm. Considerable residual anisotropy appears at long times, proving that local ordering exists in the Chl a-protein core antenna of PSI-60. At these four wavelengths, the polarization decays with mean lifetimes between 2.9 and 6.6 ps. This slow time scale suggests that the depolarization accompanies electronic excitation transport between clusters of Chl a chromophores rather than between individual nearest-neighbor chromophores.

  8. Facile preparation of core@shell and concentration-gradient spinel particles for Li-ion battery cathode materials

    NASA Astrophysics Data System (ADS)

    Kozawa, Takahiro; Naito, Makio

    2015-02-01

    Core@shell and concentration-gradient particles have attracted much attention as improved cathodes for Li-ion batteries (LIBs). However, most of their preparation routes have employed a precisely-controlled co-precipitation method. Here, we report a facile preparation route of core@shell and concentration-gradient spinel particles by dry powder processing. The core@shell particles composed of the MnO2 core and the Li(Ni,Mn)2O4 spinel shell are prepared by mechanical treatment using an attrition-type mill, whereas the concentration-gradient spinel particles with an average composition of LiNi0.32Mn1.68O4 are produced by calcination of their core@shell particles as a precursor. The concentration-gradient LiNi0.32Mn1.68O4 spinel cathode exhibits the high discharge capacity of 135.3 mA h g-1, the wide-range plateau at a high voltage of 4.7 V and the cyclability with a capacity retention of 99.4% after 20 cycles. Thus, the facile preparation route of the core@shell and concentration-gradient particles may provide a new opportunity for the discovery and investigation of functional materials as well as for the cathode materials for LIBs.

  9. Facile preparation of core@shell and concentration-gradient spinel particles for Li-ion battery cathode materials

    PubMed Central

    Kozawa, Takahiro; Naito, Makio

    2015-01-01

    Core@shell and concentration-gradient particles have attracted much attention as improved cathodes for Li-ion batteries (LIBs). However, most of their preparation routes have employed a precisely-controlled co-precipitation method. Here, we report a facile preparation route of core@shell and concentration-gradient spinel particles by dry powder processing. The core@shell particles composed of the MnO2 core and the Li(Ni,Mn)2O4 spinel shell are prepared by mechanical treatment using an attrition-type mill, whereas the concentration-gradient spinel particles with an average composition of LiNi0.32Mn1.68O4 are produced by calcination of their core@shell particles as a precursor. The concentration-gradient LiNi0.32Mn1.68O4 spinel cathode exhibits the high discharge capacity of 135.3 mA h g−1, the wide-range plateau at a high voltage of 4.7 V and the cyclability with a capacity retention of 99.4% after 20 cycles. Thus, the facile preparation route of the core@shell and concentration-gradient particles may provide a new opportunity for the discovery and investigation of functional materials as well as for the cathode materials for LIBs. PMID:27877756

  10. Facile preparation of core@shell and concentration-gradient spinel particles for Li-ion battery cathode materials.

    PubMed

    Kozawa, Takahiro; Naito, Makio

    2015-02-01

    Core@shell and concentration-gradient particles have attracted much attention as improved cathodes for Li-ion batteries (LIBs). However, most of their preparation routes have employed a precisely-controlled co-precipitation method. Here, we report a facile preparation route of core@shell and concentration-gradient spinel particles by dry powder processing. The core@shell particles composed of the MnO2 core and the Li(Ni,Mn)2O4 spinel shell are prepared by mechanical treatment using an attrition-type mill, whereas the concentration-gradient spinel particles with an average composition of LiNi0.32Mn1.68O4 are produced by calcination of their core@shell particles as a precursor. The concentration-gradient LiNi0.32Mn1.68O4 spinel cathode exhibits the high discharge capacity of 135.3 mA h g(-1), the wide-range plateau at a high voltage of 4.7 V and the cyclability with a capacity retention of 99.4% after 20 cycles. Thus, the facile preparation route of the core@shell and concentration-gradient particles may provide a new opportunity for the discovery and investigation of functional materials as well as for the cathode materials for LIBs.

  11. Synthesis, molecular docking and evaluation of antifungal activity of Ni(II), Co(II) and Cu(II) complexes of porphyrin core macromolecular ligand.

    PubMed

    Singh, Urvashi; Malla, Ali Mohammad; Bhat, Imtiyaz Ahmad; Ahmad, Ajaz; Bukhari, Mohd Nadeem; Bhat, Sneha; Anayutullah, Syed; Hashmi, Athar Adil

    2016-04-01

    Porphyrin core dendrimeric ligand (L) was synthesized by Rothemund synthetic route in which p-hydroxy benzaldehyde and pyrrole were fused together. The prepared ligand was complexed with Ni(II), Cu(II) and Co(II) ions, separately. Both the ligand and its complexes were characterized by elemental analysis and spectroscopic studies (FT-IR, UV-Vis, (1)HNMR). Square planar geometries were proposed for Cu(II), Ni(II) and Co(II) ions in cobalt, Nickel and copper complexes, respectively on the basis of UV-Vis spectroscopic data. The ligand and its complex were screened on Candida albicans (ATCC 10231), Aspergillus fumigatus (ATCC 1022), Trichophyton mentagrophytes (ATCC 9533) and Pencillium marneffei by determining MICs and inhibition zones. The activity of the ligand and its complexes was found to be in the order: CuL ˃ CoL ≈ NiL ˃ L. Detection of DNA damage at the level of the individual eukaryotic cell was observed by commet assay. Molecular docking technique was used to understand the ligand-DNA interactions. From docking experiment, we conclude that copper complex interacts more strongly than rest two.

  12. Starvation Induces Proteasome Autophagy with Different Pathways for Core and Regulatory Particles.

    PubMed

    Waite, Kenrick A; De-La Mota-Peynado, Alina; Vontz, Gabrielle; Roelofs, Jeroen

    2016-02-12

    The proteasome is responsible for the degradation of many cellular proteins. If and how this abundant and normally stable complex is degraded by cells is largely unknown. Here we show that in yeast, upon nitrogen starvation, proteasomes are targeted for vacuolar degradation through autophagy. Using GFP-tagged proteasome subunits, we observed that autophagy of a core particle (CP) subunit depends on the deubiquitinating enzyme Ubp3, although a regulatory particle (RP) subunit does not. Furthermore, upon blocking of autophagy, RP remained largely nuclear, although CP largely localized to the cytosol as well as granular structures within the cytosol. In all, our data reveal a regulated process for the removal of proteasomes upon nitrogen starvation. This process involves CP and RP dissociation, nuclear export, and independent vacuolar targeting of CP and RP. Thus, in addition to the well characterized transcriptional up-regulation of genes encoding proteasome subunits, cells are also capable of down-regulating cellular levels of proteasomes through proteaphagy.

  13. Site-specific aflatoxin B sub 1 adduction of sequence-positioned nucleosome core particles

    SciTech Connect

    Moyer, R.A.

    1988-01-01

    The question of how the presence of nucleosomal packing of DNA modifies carcinogen interaction at specific sites cannot be answered by studies on whole chromatin or bulk nucleosomes because of the heterogeneity of DNA sequences in the particles. This problem was circumvented by constructing nucleosomes that are homogenous in DNA-histone contact points. A cloned DNA fragment, containing a sea urchin 5S gene which precisely positions a histone octamer was employed. By using {sup 32}P end-labeled DNA and genotoxins that allow cleavage at sites of attack, the frequency of adduction at every susceptible nucleotide can be determined on sequencing gels. The small methylating agent dimethyl sulfate (DMS) and the bulky alkylating agent afatoxin B{sub 1}-dichloride (AFB{sub 1}-Cl{sub 2}) were used to probe the influence of DNA-histone interactions on DNA alkylation patterns in sequence-positioned core particles.

  14. Salt-induced conformation and interaction changes of nucleosome core particles.

    PubMed Central

    Mangenot, Stéphanie; Leforestier, Amélie; Vachette, Patrice; Durand, Dominique; Livolant, Françoise

    2002-01-01

    Small angle x-ray scattering was used to follow changes in the conformation and interactions of nucleosome core particles (NCP) as a function of the monovalent salt concentration C(s). The maximal extension (D(max)) of the NCP (145 +/- 3-bp DNA) increases from 137 +/- 5 A to 165 +/- 5 A when C(s) rises from 10 to 50 mM and remains constant with further increases of C(s) up to 200 mM. In view of the very weak increase of the R(g) value in the same C(s) range, we attribute this D(max) variation to tail extension, a proposal confirmed by simulations of the entire I(q) curves, considering an ideal solution of particles with tails either condensed or extended. This tail extension is observed at higher salt values when particles contain longer DNA fragments (165 +/- 10 bp). The maximal extension of the tails always coincides with the screening of repulsive interactions between particles. The second virial coefficient becomes smaller than the hard sphere virial coefficient and eventually becomes negative (net attractive interactions) for NCP(145). Addition of salt simultaneously screens Coulombic repulsive interactions between NCP and Coulombic attractive interactions between tails and DNA inside the NCP. We discuss how the coupling of these two phenomena may be of biological relevance. PMID:11751321

  15. Orbital Evolution of Particles and Stable Zones at the F Ring Core

    NASA Astrophysics Data System (ADS)

    Whizin, Akbar; Cuzzi, J.; Hogan, R.; Dobrovolskis, A.; Colwell, J.; Scargle, J.; Dones, L.; Showalter, M.

    2012-10-01

    The F ring of Saturn is often thought of as a ‘shepherded’ ring; however, it is closer to the more massive of its two shepherd satellites, Prometheus. Pandora, the outer satellite, is near a 3:2 mean motion resonance with larger Mimas causing periodic fluctuations in its orbit. The perturbations from the Saturnian satellites result in chaotic orbits throughout the F ring region (Scargle et al 1993 DPS 25, #26.04, Winter et al 2007 MNRAS 380, L54; 2010 A&A 523, A67). We follow the approach of Cuzzi et al. (abstract this meeting) in exploring zones of relative stability in the F ring region using a N-body Bulirsch-Stoer orbital integrator that includes the 14 main satellites of Saturn. We find relatively stable zones situated among the tightly packed Prometheus and Pandora resonances that we dub “anti-resonances.” At these locations ring particles have much smaller changes in their semi-major axes and eccentricities than particles outside of anti-resonance zones. We present high radial resolution simulations where we track the orbital evolution of 6000 test particles over time in a 200km region and find that the variance of the semi-major axes of particles in anti-resonances can be less than 1km over a period of 32 years, while just 5km away in either radial direction the variance can be tens of km’s. More importantly, particles outside of these stable zones can migrate into one due to chaotic orbits, but once they enter an anti-resonance zone they remain there. The anti-resonances act as long-lived sinks for ring particles and explain the location of the F ring core even though it is not in overall torque balance with the shepherd moons.

  16. Saturn's Rings II. Particle Sizes Inferred from Stellar Occultation Data

    NASA Astrophysics Data System (ADS)

    French, Richard G.; Nicholson, Philip D.

    2000-06-01

    We derive power-law particle size distributions for each of Saturn's main ring regions, using observations of the 3 July 1989 stellar occultation of 28 Sgr from Palomar, McDonald, and Lick observatories. We use the Voyager PPS δ Sco optical depth profile to estimate and then remove the directly transmitted signal from the 28 Sgr observations, leaving high SNR scattered light profiles at wavelengths of 3.9, 2.1, and 0.9 μm. The angular distribution of this diffracted signal depends on the ring particle size distribution: the sharpness of the forward lobe is set by the largest particles, while the overall breadth and amplitude of the scattered signal reflect the abundance of smaller, cm-sized particles. From a simple one-dimensional scattering model, we estimate characteristic particle sizes in the A, B, and C rings, and obtain a good match to the detailed structure of the observed scattered light profiles. To accommodate more realistic particle size distributions and to take proper account of the geometry of the occultation, we then develop a two-dimensional forward-scattering model. We assume for simplicity a single power law particle size distribution for each major ring region, and we determine the index q and lower and upper size cutoffs amin and amax that provide the best match to all three data sets in each region. Our results in the A and C rings are fairly consistent with values of q and amax derived from Voyager radio occultation (RSS) measurements (Zebker et al. 1985). We extend their results by determining lower limits to the particle size distributions and by probing the B Ring. We find a rather flat ( q=2.75) and narrow size distribution for both the inner A Ring and the B Ring, with a surprisingly large amin=30 cm. From the detailed shape of the scattered signal in the A and B rings, we find amax=20 m, a factor of two larger than the RSS result. The fraction of cm-sized particles increases between the inner and outer A Ring and is greatest in the C

  17. Preparation and reactivity of a tetranuclear Fe(II) core in the metallothionein α-domain.

    PubMed

    Sano, Yohei; Onoda, Akira; Sakurai, Rie; Kitagishi, Hiroaki; Hayashi, Takashi

    2011-05-01

    Metallothioneins (MTs) are small cysteine-rich proteins which exhibit high affinities for various metal ions and play roles in storage of essential metals and detoxification of toxic metals. Studies on the redox properties of MTs have been quite limited. Recently, we focused on the α-domain of MT (MTα) as a protein matrix and incorporated a tetranuclear metal cluster as a reductant. UV-visible, CD and MS data indicate the formation of the stable tetranuclear metal-cysteine cluster in the MTα matrix with Fe(II)(4)-MTα and Co(II)(4)-MTα species existing in water. Furthermore, the Fe(II)(4)-MTα species was found to promote the reduction of met-myoglobin and azobenzene derivatives under mild conditions. Particularly, the stoichiometric reduction of methyl red with Fe(II)(4)-MTα (1:1) was found to proceed with a conversion of 98% over a period of 6h at 25°C. This indicates that all of the four Fe(II) cores contribute to the reduction. In this paper, we describe the preparation and reactivity of the tetranuclear iron cluster in the protein matrix.

  18. Modification of Particle Distributions by MHD Instabilities II

    SciTech Connect

    Roscoe B. White

    2011-03-02

    The modification of particle distributions by low amplitude magnetohydrodynamic modes is an important topic for magnetically confined plasmas. Low amplitude modes are known to be capable of producing significant modification of injected neutral beam profiles, and the same can be expected in burning plasmas for the alpha particle distributions. Flattening of a distribution in an island due to phase mixing and portions of phase space becoming stochastic lead to modification of the particle distribution, a process extremely rapid in the time scale of an experiment but still very long compared to the time scale of guiding center simulations. Large amplitude modes can cause profile avalanche and particle loss. Thus it is very valuable to be able to predict the temporal evolution of a particle distribution produced by a given spectrum of magnetohydrodynamic modes. In this paper we further develop and investigate the use of a new method of determining domains of phase space in which good KAM surfaces do not exist and use this method to examine a well documented case of profile modification by instabilities.

  19. One-piece micropumps from liquid crystalline core-shell particles

    NASA Astrophysics Data System (ADS)

    Fleischmann, Eva-Kristina; Liang, Hsin-Ling; Kapernaum, Nadia; Giesselmann, Frank; Lagerwall, Jan; Zentel, Rudolf

    2012-11-01

    Responsive polymers are low-cost, light weight and flexible, and thus an attractive class of materials for the integration into micromechanical and lab-on-chip systems. Triggered by external stimuli, liquid crystalline elastomers are able to perform mechanical motion and can be utilized as microactuators. Here we present the fabrication of one-piece micropumps from liquid crystalline core-shell elastomer particles via a microfluidic double-emulsion process, the continuous nature of which enables a low-cost and rapid production. The liquid crystalline elastomer shell contains a liquid core, which is reversibly pumped into and out of the particle by actuation of the liquid crystalline shell in a jellyfish-like motion. The liquid crystalline elastomer shells have the potential to be integrated into a microfluidic system as micropumps that do not require additional components, except passive channel connectors and a trigger for actuation. This renders elaborate and high-cost micromachining techniques, which are otherwise required for obtaining microstructures with pump function, unnecessary.

  20. Crystal structure of human nucleosome core particle containing enzymatically introduced CpG methylation.

    PubMed

    Fujii, Yoshifumi; Wakamori, Masatoshi; Umehara, Takashi; Yokoyama, Shigeyuki

    2016-06-01

    Cytosine methylation, predominantly of the CpG sequence in vertebrates, is one of the major epigenetic modifications crucially involved in the control of gene expression. Due to the difficulty of reconstituting site-specifically methylated nucleosomal DNA at crystallization quality, most structural analyses of CpG methylation have been performed using chemically synthesized oligonucleotides, There has been just one recent study of nucleosome core particles (NCPs) reconstituted with nonpalindromic human satellite 2-derived DNAs. Through the preparation of a 146-bp palindromic α-satellite-based nucleosomal DNA containing four CpG dinucleotide sequences and its enzymatic methylation and restriction, we reconstituted a 'symmetric' human CpG-methylated nucleosome core particle (NCP). We solved the crystal structures of the CpG-methylated and unmodified NCPs at 2.6 and 3.0 Å resolution, respectively. We observed the electron densities of two methyl groups, among the eight 5-methylcytosines introduced in the CpG-fully methylated NCP. There were no obvious structural differences between the CpG-methylated 'symmetric NCP' and the unmodified NCP. The preparation of a crystallization-grade CpG-methylated NCP provides a platform for the analysis of CpG-methyl reader and eraser proteins.

  1. Comparisons of MgII core-wing data with Ground-Based Ca K-line

    NASA Astrophysics Data System (ADS)

    Chapman, G. A.; Preminger, D.

    2011-12-01

    Magnesium_II core-wing ratio data will be compared with ground-based K-line photometry for most of cycle 22 and 23. The ground-based data is the photmetric sum computed from the composite K-line obtained from the San Fernando Observatory. We will examine several MgII core-wing composites. This work is partially supported by grants NNX11AB51G from NASA and ATM-0848518 from NSF.

  2. HSDP II Drill Core: Preliminary Rock Strength Results and Implications to Flank Stability, Mauna Kea Volcano

    NASA Astrophysics Data System (ADS)

    Thompson, N.; Watters, R. J.; Schiffman, P.

    2004-12-01

    Selected portions of the 3-km HSDP II core were tested to provide unconfined rock strength data from hyaloclastite alteration zones and pillow lavas. Though the drilling project was not originally intended for strength purpose, it is believed the core can provide unique rock strength insights into the flank stability of the Hawaiian Islands. The testing showed that very weak rock exists in the hyaloclastite abundant zones in the lower 2-km of the core with strength dependent on the degree of consolidation and type of alteration. Walton and Schiffman identified three zones of alteration, an upper incipient alteration zone (1080-1335m), a smectitic zone (1405-1573m) and a lower palagonitic zone from about 1573 m to the base of the core. These three zones were sampled and tested together with pillow lava horizons for comparison. Traditional cylindrical core was not available as a consequence of the entire core having been split lengthwise for archival purposes. Hence, point load strength testing was utilized which provides the unconfined compressive strength on irregular shaped samples. The lowest unconfined strengths were recorded from incipient alteration zones with a mean value of 9.5 MPa. Smectitic alteration zones yielded mean values of 16.4 MPa, with the highest measured alteration strengths from the palagonite zones with a mean value of 32.1 MPa. As anticipated, the highest strengths were from essentially unaltered lavas with a mean value of 173 MPa. Strength variations of between one to two orders of magnitude were identified in comparing the submarine hyaloclastite with the intercalated submarine lavas. The weakest zones within the hyaloclastites may provide horizons for assisting flank collapse by serving as potential thrust zones and landslide surfaces.

  3. Basics of particle therapy II: relative biological effectiveness

    PubMed Central

    Choi, Jinhyun

    2012-01-01

    In the previous review, the physical aspect of heavy particles, with a focus on the carbon beam was introduced. Particle beam therapy has many potential advantages for cancer treatment without increasing severe side effects in normal tissue, these kinds of radiation have different biologic characteristics and have advantages over using conventional photon beam radiation during treatment. The relative biological effectiveness (RBE) is used for many biological, clinical endpoints among different radiation types and is the only convenient way to transfer the clinical experience in radiotherapy with photons to another type of radiation therapy. However, the RBE varies dependent on the energy of the beam, the fractionation, cell types, oxygenation status, and the biological endpoint studied. Thus this review describes the concerns about RBE related to particle beam to increase interests of the Korean radiation oncologists' society. PMID:23120738

  4. Co-axial capillaries microfluidic device for synthesizing size- and morphology-controlled polymer core-polymer shell particles.

    PubMed

    Chang, Zhenqi; Serra, Christophe A; Bouquey, Michel; Prat, Laurent; Hadziioannou, Georges

    2009-10-21

    An easy assembling-disassembling co-axial capillaries microfluidic device was built up for the production of double droplets. Uniform polymer core-polymer shell particles were synthesized by polymerizing the two immiscible monomer phases composing the double droplet. Thus poly(acrylamide) core-poly(tri(propylene glycol) diacrylate) shell particles with controlled core diameter and shell thickness were simply obtained by adjusting operating parameters. An empirical law was extracted from experiments to predict core and shell sizes. Additionally uniform and predictable non-spherical polymer objects were also prepared without adding shape-formation procedures in the experimental device. An empirical equation for describing the lengths of rod-like polymer particles is also presented.

  5. A chromospheric dark-cored fibril in Ca II IR spectra

    NASA Astrophysics Data System (ADS)

    Beck, C.; Tritschler, A.; Wöger, F.

    2010-06-01

    We investigate the thermodynamical and magnetic properties of a ``dark-cored" fibril seen in the chromospheric Ca II IR line at 854.2 nm to determine the physical process behind its appearance. We analyse a time series of spectropolarimetric observations obtained in the Ca II IR line at 854.2 nm and the photospheric Fe I line at 630.25 nm. We simultaneously invert the spectra in both wavelength ranges with the SIR code to obtain the temperature and velocity stratification with height in the solar atmosphere and the magnetic field properties in the photosphere. The structure can be clearly traced in the line-of-sight (LOS) velocity and the temperature maps. It connects from a small pore with kG fields to a region with lower field strength. The flow velocity and the temperature indicate that the height of the structure increases with increasing distance from the inner footpoint. The Stokes V signal of 854.2 nm shows a Doppler-shifted polarization signal with the same displacement as in the intensity profile, indicating that the supersonic flow seen in the LOS velocity is located within magnetized plasma. We conclude that the chromospheric dark-cored fibril traces a siphon flow along magnetic field lines, driven by the gas pressure difference caused by the higher magnetic field strength at the inner footpoint. We suggest that fast flows guided by the magnetic field lead to the appearance of ``dark-cored" fibrils in intensity images. Although the observations included the determination of the polarization signal in the chromospheric Ca II IR line, the signal could not be analysed quantitatively due to the low S/N. Chromospheric polarimetry will thus require telescopes of larger aperture able to collect a sufficient number of photons for a reliable determination of polarization in deep and only weakly polarized spectral lines.

  6. Composition of individual particles in the wakes of an Athena II rocket and the space shuttle

    NASA Astrophysics Data System (ADS)

    Cziczo, D. J.; Murphy, D. M.; Thomson, D. S.; Ross, M. N.

    2002-11-01

    The Particle Analysis by Laser Mass Spectrometry (PALMS) instrument was used to obtain the first in situ measurements of the composition of particles in the wakes of solid rocket motor (SRMs) launch vehicles. PALMS acquired mass spectra of over 2300 exhaust particles within the plumes of an Athena II rocket and the Space Shuttle. The majority of positive spectra indicated the presence of primary and trace components of the aluminum fuel and the combustion catalyst. Negative spectra showed chlorine from the oxidizer. Nitrate and phosphate fragments and water were common features of spectra acquired during the Space Shuttle encounters. Elemental carbon (EC) was a significant particle type observed in the Athena II plume. The data show that particles emitted by SRMs are more diverse and probably more reactive than previously considered.

  7. An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations. Part II: Liquid freshwater

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Ilicak, Mehmet; Gerdes, Rüdiger; Drange, Helge; Aksenov, Yevgeny; Bailey, David A.; Bentsen, Mats; Biastoch, Arne; Bozec, Alexandra; Böning, Claus; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Curry, Beth; Danabasoglu, Gokhan; Danilov, Sergey; Fernandez, Elodie; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Iovino, Doroteaciro; Jahn, Alexandra; Jung, Thomas; Large, William G.; Lee, Craig; Lique, Camille; Lu, Jianhua; Masina, Simona; Nurser, A. J. George; Rabe, Benjamin; Roth, Christina; Salas y Mélia, David; Samuels, Bonita L.; Spence, Paul; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Xuezhu; Yeager, Steve G.

    2016-03-01

    The Arctic Ocean simulated in 14 global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II) is analyzed in this study. The focus is on the Arctic liquid freshwater (FW) sources and freshwater content (FWC). The models agree on the interannual variability of liquid FW transport at the gateways where the ocean volume transport determines the FW transport variability. The variation of liquid FWC is induced by both the surface FW flux (associated with sea ice production) and lateral liquid FW transport, which are in phase when averaged on decadal time scales. The liquid FWC shows an increase starting from the mid-1990s, caused by the reduction of both sea ice formation and liquid FW export, with the former being more significant in most of the models. The mean state of the FW budget is less consistently simulated than the temporal variability. The model ensemble means of liquid FW transport through the Arctic gateways compare well with observations. On average, the models have too high mean FWC, weaker upward trends of FWC in the recent decade than the observation, and low consistency in the temporal variation of FWC spatial distribution, which needs to be further explored for the purpose of model development.

  8. Papain digestion of crude Trichoderma reesei cellulase: Purification and properties of cellobiohydrolase I and II core proteins

    SciTech Connect

    Woodward, J.; Brown, J.P.; Evans, B.R.; Affholter, K.A.

    1992-12-01

    Papain digestion of a crude Trichoderma reesei cellulose preparation followed by gel filtration on a Superdex column resulted in the separation of cellobiohydrolase (CBH) I and II core proteins (cp). They were further purified to apparent homogeneity by chromatofocusing. N-terminal protein sequencing of the CBH II cp preparation confirmed its identity. A comparison of the catalytic activity and cellulose-binding ability of these core proteins was made. The major differences between them were the findings that CBH II cp possessed a sixfold higher specific activity toward p-nitrophenylcellobioside than the native CBH II preparation and still bound to microcrystalline cellulose, unlike CBH I cp. Neither CBH I cp nor CBH II cp had activity toward carboxymethylcellulose, but both were able to hydrolyze barley b-glucan. These data suggest that removal of the cellulose-binding domain and hinge region from CBH I and II have different effects on their properties.

  9. Papain digestion of crude Trichoderma reesei cellulase: Purification and properties of cellobiohydrolase I and II core proteins

    SciTech Connect

    Woodward, J.; Brown, J.P.; Evans, B.R.; Affholter, K.A.

    1992-01-01

    Papain digestion of a crude Trichoderma reesei cellulose preparation followed by gel filtration on a Superdex column resulted in the separation of cellobiohydrolase (CBH) I and II core proteins (cp). They were further purified to apparent homogeneity by chromatofocusing. N-terminal protein sequencing of the CBH II cp preparation confirmed its identity. A comparison of the catalytic activity and cellulose-binding ability of these core proteins was made. The major differences between them were the findings that CBH II cp possessed a sixfold higher specific activity toward p-nitrophenylcellobioside than the native CBH II preparation and still bound to microcrystalline cellulose, unlike CBH I cp. Neither CBH I cp nor CBH II cp had activity toward carboxymethylcellulose, but both were able to hydrolyze barley b-glucan. These data suggest that removal of the cellulose-binding domain and hinge region from CBH I and II have different effects on their properties.

  10. The treatment of mixing in core helium burning models - II. Constraints from cluster star counts

    NASA Astrophysics Data System (ADS)

    Constantino, Thomas; Campbell, Simon W.; Lattanzio, John C.; van Duijneveldt, Adam

    2016-03-01

    The treatment of convective boundaries during core helium burning is a fundamental problem in stellar evolution calculations. In the first paper of this series, we showed that new asteroseismic observations of these stars imply they have either very large convective cores or semiconvection/partially mixed zones that trap g modes. We probe this mixing by inferring the relative lifetimes of asymptotic giant branch (AGB) and horizontal branch (HB) from R2, the observed ratio of these stars in recent HST photometry of 48 Galactic globular clusters. Our new determinations of R2 are more self-consistent than those of previous studies and our overall calculation of R2 = 0.117 ± 0.005 is the most statistically robust now available. We also establish that the luminosity difference between the HB and the AGB clump is Δ log {L}_HB^AGB = 0.455 ± 0.012. Our results accord with earlier findings that standard models predict a lower R2 than is observed. We demonstrate that the dominant sources of uncertainty in models are the prescription for mixing and the stochastic effects that can result from its numerical treatment. The luminosity probability density functions that we derive from observations feature a sharp peak near the AGB clump. This constitutes a strong new argument against core breathing pulses, which broaden the predicted width of the peak. We conclude that the two mixing schemes that can match the asteroseismology are capable of matching globular cluster observations, but only if (i) core breathing pulses are avoided in models with a semiconvection/partially mixed zone, or (ii) that models with large convective cores have a particular depth of mixing beneath the Schwarzschild boundary during subsequent early-AGB `gravonuclear' convection.

  11. Adhesion phenomena between particles according to the content of organic binder in core for thin-wall casting.

    PubMed

    Kim, Eun-Hee; Cho, Geon-Ho; Jung, Yeon-Gil; Kim, In-Soo; Jo, Chang-Young; Lee, Jin-Seok

    2014-10-01

    The content of organic binder in a core for thin-wall casting has been controlled to investigate the adhesion phenomena of inorganic binder between starting particles, as directly related to the mechanical and thermal properties of the core. The inorganic binder precursor was composed of tetraethyl orthosilicate and sodium methoxide as the silicon dioxide and sodium oxide precursors, respectively. Poly(vinyl alcohol), a hydrophilic polymer, was used as an organic binder. The particles coated with the inorganic precursor were sculpted with the organic binder and then the prepared core samples were heated at 1000 degrees C for 1 h. The core samples prepared with the optimum content of organic binder show the highest fracture strength. This may be due to the enhancement of adhesion by the glass phase formed between starting particles. However, when too much or too little organic binder is employed, the strength values of the core samples are significantly decreased. This is because the network structure of the glass phase is not inadequately created or the glass phase is not uniformly developed between starting particles, resulting in the insufficient contact between starting particles during the convert process.

  12. Rapid microwave synthesis and photoluminescence properties of rare earth-based coordination polymer core-shell particles

    NASA Astrophysics Data System (ADS)

    Huang, Shuang; Xu, Hualan; Wang, Mengya; Zhong, Shengliang; Zeng, Chenghui

    2016-12-01

    Coordination polymer (CP) core-shell particles, with Eu-based CP as the core and La-based CP as the shell, were prepared using a facile microwave heating method. Pyridine-2, 5-dicarboxylic acid (PDA) was selected as the organic building blo, and DMF was used as the solvent. SEM and TEM images show that the resultant cores are nanospheres with diameters of 200-400 nm. Products with different shell thickness were prepared. The luminescence properties of the core-shell structures were studied and the influence of the La-based CP shell on the photoluminescence properties of the core were investigated. The fluorescence intensity and lifetime of the Eu-based CP core were varied with the addition of shell thickness. Both of them increases at first and then decreases with the increase of shell thickness.

  13. The structure of nucleosomal core particles within transcribed and repressed gene regions.

    PubMed Central

    Studitsky, V M; Belyavsky, A V; Melnikova, A F; Mirzabekov, A D

    1988-01-01

    The arrangement of histones along DNA in nucleosomal core particles within transcribed heat shock gene (hsp 70) region and repressed insertion within ribosomal genes of Drosophila was analysed by using protein-DNA crosslinking methods combined with hybridization tests. In addition, two-dimensional gel electrophoresis was employed to compare the overall nucleosomal shape and the nucleosomal DNA size. The arrangement of histones along DNA and general compactness of nucleosomes were shown to be rather similar in transcriptionally active and inactive genomic regions. On the other hand, nucleosomes within transcriptionally active chromatin are characterized by a larger size of nucleosomal DNA produced by micrococcal nuclease digestion and some peculiarity in electrophoretic mobility. Images PMID:3144704

  14. The H1 linker histones: multifunctional proteins beyond the nucleosomal core particle

    PubMed Central

    Hergeth, Sonja P; Schneider, Robert

    2015-01-01

    The linker histone H1 family members are a key component of chromatin and bind to the nucleosomal core particle around the DNA entry and exit sites. H1 can stabilize both nucleosome structure and higher-order chromatin architecture. In general, H1 molecules consist of a central globular domain with more flexible tail regions at both their N- and C-terminal ends. The existence of multiple H1 subtypes and a large variety of posttranslational modifications brings about a considerable degree of complexity and makes studying this protein family challenging. Here, we review recent progress in understanding the function of linker histones and their subtypes beyond their role as merely structural chromatin components. We summarize current findings on the role of H1 in heterochromatin formation, transcriptional regulation and embryogenesis with a focus on H1 subtypes and their specific modifications. PMID:26474902

  15. Assembly Pathway of Hepatitis B Core Virus-like Particles from Genetically Fused Dimers*

    PubMed Central

    Holmes, Kris; Shepherd, Dale A.; Ashcroft, Alison E.; Whelan, Mike; Rowlands, David J.; Stonehouse, Nicola J.

    2015-01-01

    Macromolecular complexes are responsible for many key biological processes. However, in most cases details of the assembly/disassembly of such complexes are unknown at the molecular level, as the low abundance and transient nature of assembly intermediates make analysis challenging. The assembly of virus capsids is an example of such a process. The hepatitis B virus capsid (core) can be composed of either 90 or 120 dimers of coat protein. Previous studies have proposed a trimer of dimers as an important intermediate species in assembly, acting to nucleate further assembly by dimer addition. Using novel genetically-fused coat protein dimers, we have been able to trap higher-order assembly intermediates and to demonstrate for the first time that both dimeric and trimeric complexes are on pathway to virus-like particle (capsid) formation. PMID:25953902

  16. Meaningful timescales from Monte Carlo simulations of particle systems with hard-core interactions

    NASA Astrophysics Data System (ADS)

    Costa, Liborio I.

    2016-12-01

    A new Markov Chain Monte Carlo method for simulating the dynamics of particle systems characterized by hard-core interactions is introduced. In contrast to traditional Kinetic Monte Carlo approaches, where the state of the system is associated with minima in the energy landscape, in the proposed method, the state of the system is associated with the set of paths traveled by the atoms and the transition probabilities for an atom to be displaced are proportional to the corresponding velocities. In this way, the number of possible state-to-state transitions is reduced to a discrete set, and a direct link between the Monte Carlo time step and true physical time is naturally established. The resulting rejection-free algorithm is validated against event-driven molecular dynamics: the equilibrium and non-equilibrium dynamics of hard disks converge to the exact results with decreasing displacement size.

  17. The H1 linker histones: multifunctional proteins beyond the nucleosomal core particle.

    PubMed

    Hergeth, Sonja P; Schneider, Robert

    2015-11-01

    The linker histone H1 family members are a key component of chromatin and bind to the nucleosomal core particle around the DNA entry and exit sites. H1 can stabilize both nucleosome structure and higher-order chromatin architecture. In general, H1 molecules consist of a central globular domain with more flexible tail regions at both their N- and C-terminal ends. The existence of multiple H1 subtypes and a large variety of posttranslational modifications brings about a considerable degree of complexity and makes studying this protein family challenging. Here, we review recent progress in understanding the function of linker histones and their subtypes beyond their role as merely structural chromatin components. We summarize current findings on the role of H1 in heterochromatin formation, transcriptional regulation and embryogenesis with a focus on H1 subtypes and their specific modifications.

  18. Construction of a Ca II Core-to-Wing Ratio Image

    NASA Astrophysics Data System (ADS)

    Roberts, H.

    2015-12-01

    To understand Earth's climate, we must first understand the Sun. However, there are still significant uncertainties associated with both the fundamental mechanisms of solar variability and how they enter into the Earth's climate system. An important method to study the causes of solar variability can be found through the analysis of solar images. The Precision Solar Photometric Telescope (PSPT) located at the Mauna Loa Solar Observatory (MLSO) acquires images of the Sun in three different photometric bands to monitor the evolution of solar surface features that change over the course of a solar cycle. These images provide a complete knowledge about the Sun by targeting different layers of the solar atmosphere. Though raw images are meaningful and important, precision image processing is required to remove instrumental artifacts and false features that may appear in these images prior to usage for scientific purposes. A scientific application of the high precision solar images is investigated by analyzing a set of narrow band of Calcium II K core and wing images. The Core and Wing images are processed to remove the influence of the center-to-limb variation; the resultant core-to-wing ratio image enhances the appearance of network structures on the entire solar disk along with the more obvious facula and plage brightening associated with the passage of active regions.

  19. Geodesic motions of test particles in a relativistic core-shell spacetime

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Wu, Xin; Huang, Guoqing

    2017-02-01

    In this paper, we discuss the geodesic motions of test particles in the intermediate vacuum between a monopolar core and an exterior shell of dipoles, quadrupoles and octopoles. The radii of the innermost stable circular orbits at the equatorial plane depend only on the quadrupoles. A given oblate quadrupolar leads to the existence of two innermost stable circular orbits, and their radii are larger than in the Schwarzschild spacetime. However, a given prolate quadrupolar corresponds to only one innermost stable circular orbit, and its radius is smaller than in the Schwarzschild spacetime. As to the general geodesic orbits, one of the recently developed extended phase space fourth order explicit symplectic-like methods is efficiently applicable to them although the Hamiltonian of the relativistic core-shell system is not separable. With the aid of both this fast integrator without secular growth in the energy errors and gauge invariant chaotic indicators, the effect of these shell multipoles on the geodesic dynamics of order and chaos is estimated numerically.

  20. Influence of particle size and shell thickness of core-shell packing materials on optimum experimental conditions in preparative chromatography.

    PubMed

    Horváth, Krisztián; Felinger, Attila

    2015-08-14

    The applicability of core-shell phases in preparative separations was studied by a modeling approach. The preparative separations were optimized for two compounds having bi-Langmuir isotherms. The differential mass balance equation of chromatography was solved by the Rouchon algorithm. The results show that as the size of the core increases, larger particles can be used in separations, resulting in higher applicable flow rates, shorter cycle times. Due to the decreasing volume of porous layer, the loadability of the column dropped significantly. As a result, the productivity and economy of the separation decreases. It is shown that if it is possible to optimize the size of stationary phase particles for the given separation task, the use of core-shell phases are not beneficial. The use of core-shell phases proved to be advantageous when the goal is to build preparative column for general purposes (e.g. for purification of different products) in small scale separations.

  1. A new coincidence model for single particle counters, Part II: Advances and applications.

    PubMed

    Knapp, J Z; Lieberman, A; Abramson, L R

    1994-01-01

    Accuracy, acceptance limits and methods for U.S.P. (788) contaminating particle assays published in the XXII Revision are refined in U.S.P. XXIII. In both Revisions, although different numerical values and methods are employed, particle contamination limits remain constants for all S.V.I. container volumes. The effect of this quality standard is high particle concentration acceptance limits in the smallest S.V.I. container sizes. The effect of these high concentrations is to introduce both undercount errors and false counts into U.S.P. (788) SVI contaminating particle assays. There is general agreement that the count of high concentrations of particles by a single particle light extinction counter result in an increase of the average size of the distribution of particles reported and a decrease in their total number. The error mechanism is termed "signal coincidence." Understanding and control of both these problems is unified with the introduction of the count efficiency parameter. Part I of this paper makes available two core concepts with which evaluation and control of coincidence error in single particle counters can be accurately quantified. These two core concepts are the "Particle Triggered Poisson Model," a new more accurate statistical model of the particle counting process and a concentration measure that includes the effect of particle size on the counting capability of a detector. Use of these concepts make it possible to evaluate particle detector count efficiency capability from experimental data of the coincidence effect. This is an application paper. It combines the theory in the Part I paper with the replicability of particle counters into a simple test protocol. The test results can be used to calculate a contour of particle size and count within which both undercount errors and the introduction of false counts into U.S.P. (788) particle assays are controlled. From the data analyzed it can be seen that any single particle size test cannot

  2. Core-shell-structured silica/polyacrylate particles prepared by Pickering emulsion: influence of the nucleation model on particle interfacial organization and emulsion stability.

    PubMed

    Ji, Jing; Shu, Shi; Wang, Feng; Li, Zhilin; Liu, Jingjun; Song, Ye; Jia, Yi

    2014-01-01

    This work reports a new evidence of the versatility of silica sol as a stabilizer for Pickering emulsions. The organization of silica particles at the oil-water interface is a function of the nucleation model. The present results show that nucleation model, together with monomer hydrophobicity, can be used as a trigger to modify the packing density of silica particles at the oil-water interface: Less hydrophobic methylmethacrylate, more wettable with silica particles, favors the formation of core-shell-structured composite when the composite particles are prepared by miniemulsion polymerization in which monomers are fed in batch (droplet nucleation). By contrast, hydrophobic butylacrylate promotes the encapsulating efficiency of silica when monomers are fed dropwise (homogeneous nucleation). The morphologies of polyacrylate-nano-SiO2 composites prepared from different feed ratio of methylmethacrylate/butylacrylate (with different hydrophobicity) and by different feed processes are characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. The results from SEM and TEM show that the morphologies of the as-prepared polyacrylate/nano-SiO2 composite can be a core-shell structure or a bare acrylic sphere. The stability of resulting emulsions composed of these composite particles is strongly dependent on the surface coverage of silica particles. The emulsion stability is improved by densely silica-packed composite particles.

  3. The structure of small, vapor-deposited particles. II - Experimental study of particles with hexagonal profile

    NASA Technical Reports Server (NTRS)

    Yacaman, M. J.; Heinemann, K.; Yang, C. Y.; Poppa, H.

    1979-01-01

    'Multiply-twinned' gold particles with hexagonal bright field TEM profile were determined to be icosahedra composed of 20 identical and twin-related tetrahedral building units that do not have an fcc structure. The crystal structure of these slightly deformed tetrahedra is rhombohedral. Experimental evidence supporting this particle model was obtained by selected-zone dark field and weak beam dark field electron microscopy. In conjunction with the results of part I, it has been concluded that multiply-twinned gold particles of pentagonal or hexagonal profile that are found during the early stages of the vapor deposition growth process on alkali halide surfaces do not have an fcc crystal structure, which is in obvious contrast to the structure of bulk gold.

  4. Charged-particle mutagenesis II. Mutagenic effects of high energy charged particles in normal human fibroblasts

    NASA Technical Reports Server (NTRS)

    Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

    1994-01-01

    The biological effects of high LET charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 micrometer2 and 0.09 to 5.56 x 10(-3) micrometer2, respectively. The maximum values were obtained by 56Fe with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(-5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

  5. Charged-particle mutagenesis II. Mutagenic effects of high energy charged particles in normal human fibroblasts

    NASA Astrophysics Data System (ADS)

    Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

    1994-10-01

    The biological effects of high LET charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/μm to 975 KeV/gmm with particle energy (on the cells) between 94 - 603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/μm. The inactivation cross-section (αi) and the action-section for mutant induction (αm) ranged from 2.2 to 92.0 μm2 and 0.09 to 5.56 × 10-3 μm2, respectively. The maximum values were obtained by 56Fe with an LET of 200 keV/μm. The mutagenicity (αm/αi) ranged from 2.05 to 7.99 × 10-5 with the maximum value at 150 keV/μm. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

  6. Spectroscopic properties of photosystem II core complexes from Thermosynechococcus elongatus revealed by single-molecule experiments.

    PubMed

    Brecht, Marc; Skandary, Sepideh; Hellmich, Julia; Glöckner, Carina; Konrad, Alexander; Hussels, Martin; Meixner, Alfred J; Zouni, Athina; Schlodder, Eberhard

    2014-06-01

    In this study we use a combination of absorption, fluorescence and low temperature single-molecule spectroscopy to elucidate the spectral properties, heterogeneities and dynamics of the chlorophyll a (Chla) molecules responsible for the fluorescence emission of photosystem II core complexes (PS II cc) from the cyanobacterium Thermosynechococcus elongatus. At the ensemble level, the absorption and fluorescence spectra show a temperature dependence similar to plant PS II. We report emission spectra of single PS II cc for the first time; the spectra are dominated by zero-phonon lines (ZPLs) in the range between 680 and 705nm. The single-molecule experiments show unambiguously that different emitters and not only the lowest energy trap contribute to the low temperature emission spectrum. The average emission spectrum obtained from more than hundred single complexes shows three main contributions that are in good agreement with the reported bands F685, F689 and F695. The intensity of F695 is found to be lower than in conventional ensemble spectroscopy. The reason for the deviation might be due to the accumulation of triplet states on the red-most chlorophylls (e.g. Chl29 in CP47) or on carotenoids close to these long-wavelength traps by the high excitation power used in the single-molecule experiments. The red-most emitter will not contribute to the fluorescence spectrum as long as it is in the triplet state. In addition, quenching of fluorescence by the triplet state may lead to a decrease of long-wavelength emission.

  7. Magnetorheology of core-shell carbonyl iron/ZnO rod-like particle silicone oil suspensions under oscillatory shear

    NASA Astrophysics Data System (ADS)

    Mrlik, M.; Machovsky, M.; Pavlinek, V.; Kuritka, I.

    2015-04-01

    The aim of this study is a preparation and application of inorganic coating on the surface of carbonyl iron particles. The two step solvothermal synthesis provides core-shell CI/ZnO rod-like morphology. Compact coating of particles has a slightly negative impact on their magnetic properties (measured for magnetic field strength in the range from 0 to 213 mT); however, there is a suitable magnetorheological performance investigated under oscillatory shear, suitable to be applied in real applications.

  8. Single Particle Analysis of Oceanic Suspended Matters During the SEEDS II Iron Fertilization Experiment

    NASA Astrophysics Data System (ADS)

    Iwamoto, Y.; Narita, Y.; Uematsu, M.

    2006-12-01

    Oceanic suspended particles play an important role regulating the chemical composition of seawater through the removal of trace elements from surface water to deep water and their lateral transport. Therefore, physical and chemical properties of these particles reflect the characteristics of water mass and marine ecosystem under the perturbation of marine environment such as iron fertilization. To consider the physical and/or chemical variation of these particles in the water column, it is necessary to analyze size, number and chemical composition of individual particles. Suspended particles in the surface seawater were collected during the SEEDS II (Subarctic Iron Experiment for Ecosystem and Dynamics Study II) iron fertilization experiment in the summer of 2004. The particulate samples were analyzed by Electron probe X-ray micro analyzer (EPMA) and characterized by size and major and minor elements ranged from 0.4 to 10 μ m in diameter. These particles were classified into five groups based on their chemical compositions: Al-Si, Si-rich, Ca-rich, Organic and Others. Most of particles were Si-rich, Ca-rich and Organic. Si-rich and Ca-rich particles were mainly consist of detritus of phytoplankton.In the iron-fertilized patch area, Chl-a concentration covaried with dry weight, number and volume concentrations of the suspended particles. At 20 m depth, the number concentration of Organic particles having two peaks at 1.1 and 0.65 μ m in diameter increased within 2 days after the iron fertilization, and then gradually increased. It is suggested that the increase in suspended particles, mostly detritus of planktonic shells, corresponded to that in primary production. The contents by weight of Si in Si-rich particle and the content by weight of Ca in Ca-rich particle tended to decrease in size. In fine mode particle, Si-rich and Ca-rich particles contained more P and S as biolimiting elements and less Al, Ti, Mn, and Fe as crustal elements. The smaller Organic

  9. Determination of and evidence for non-core-shell structure of particles containing black carbon using the Single-Particle Soot Photometer (SP2)

    NASA Astrophysics Data System (ADS)

    Sedlacek, Arthur J., III; Lewis, Ernie R.; Kleinman, Lawrence; Xu, Jianzhong; Zhang, Qi

    2012-03-01

    The large uncertainty associated with black carbon (BC) direct forcing is due, in part, to the dependence of light absorption of BC-containing particles on the position of the BC within the particle. It is predicted that this absorption will be greatest for an idealized core-shell configuration in which the BC is a sphere at the center of the particle whereas much less absorption should be observed for particles in which the BC is located near or on the surface. Such microphysical information on BC-containing particles has previously been provided only by labor-intensive microscopy techniques, thus often requiring that climate modelers make assumptions about the location of the BC within the particle that are based more on mathematical simplicity than physical reality. The present paper describes a novel analysis method that utilizes the temporal behavior of the scattering and incandescence signals from individual particles containing refractory BC (rBC) measured by the Single-Particle Soot Photometer (SP2) to distinguish particles with rBC near the surface from those that have structures more closely resembling the core-shell configuration. This approach permits collection of a high-time-resolution data set of the fraction of rBC-containing particles with rBC near the surface. By application of this method to a plume containing tracers for biomass burning, it was determined that this fraction was greater than 60%. Such a data set will not only provide previously unavailable information to the climate modeling community, allowing greater accuracy in calculating rBC radiative forcing, but also will yield insight into aerosol processes.

  10. Long-rising Type II supernovae from Palomar Transient Factory and Caltech Core-Collapse Project

    NASA Astrophysics Data System (ADS)

    Taddia, F.; Sollerman, J.; Fremling, C.; Migotto, K.; Gal-Yam, A.; Armen, S.; Duggan, G.; Ergon, M.; Filippenko, A. V.; Fransson, C.; Hosseinzadeh, G.; Kasliwal, M. M.; Laher, R. R.; Leloudas, G.; Leonard, D. C.; Lunnan, R.; Masci, F. J.; Moon, D.-S.; Silverman, J. M.; Wozniak, P. R.

    2016-04-01

    Context. Supernova (SN) 1987A was a peculiar hydrogen-rich event with a long-rising (~84 d) light curve, stemming from the explosion of a compact blue supergiant star. Only a few similar events have been presented in the literature in recent decades. Aims: We present new data for a sample of six long-rising Type II SNe (SNe II), three of which were discovered and observed by the Palomar Transient Factory (PTF) and three observed by the Caltech Core-Collapse Project (CCCP). Our aim is to enlarge this small family of long-rising SNe II, characterizing their differences in terms of progenitor and explosion parameters. We also study the metallicity of their environments. Methods: Optical light curves, spectra, and host-galaxy properties of these SNe are presented and analyzed. Detailed comparisons with known SN 1987A-like events in the literature are shown, with particular emphasis on the absolute magnitudes, colors, expansion velocities, and host-galaxy metallicities. Bolometric properties are derived from the multiband light curves. By modeling the early-time emission with scaling relations derived from the SuperNova Explosion Code (SNEC) models of MESA progenitor stars, we estimate the progenitor radii of these transients. The modeling of the bolometric light curves also allows us to estimate other progenitor and explosion parameters, such as the ejected 56Ni mass, the explosion energy, and the ejecta mass. Results: We present PTF12kso, a long-rising SN II that is estimated to have the largest amount of ejected 56Ni mass measured for this class. PTF09gpn and PTF12kso are found at the lowest host metallicities observed for this SN group. The variety of early light-curve luminosities depends on the wide range of progenitor radii of these SNe, from a few tens of R⊙ (SN 2005ci) up to thousands (SN 2004ek) with some intermediate cases between 100 R⊙ (PTF09gpn) and 300 R⊙ (SN 2004em). Conclusions: We confirm that long-rising SNe II with light-curve shapes closely

  11. Multiparticle Production in Particle and Nuclear Collisions. II

    NASA Astrophysics Data System (ADS)

    Kanki, T.; Kinoshita, K.; Sumiyoshi, H.; Takagi, F.

    The dominant phenomenon in high-energy particle and nuclear collisions is multiple production of hadrons. This had attracted may physicists in 1950's, the period of the first remarkable development of particle physics. Multiparticle production was already observed in cosmic-ray experiments and expected to be explained as a natural consequence of the strong Yukawa interaction. Statistical and hydrodynamical models were then proposed by Fermi, Landau and others. These theories are still surviving even today as a prototype of modern ``fire-ball'' models. After twenty years, a golden age came in this field of physics. It was closely related to the rapid development of accelerator facilities, especially, the invention of colliding-beam machines which yield high enough center-of-mass energies for studying reactions with high multiplicity. Abundant data on final states of multiparticle production have been accumulated mainly by measuring inclusive cross sections and multiplicity distributions. In super high-energy bar{p}p collisions at CERN S pmacr pS Collider, we confirmed the increasing total cross section and found violations of many scaling laws which seemed to be valid at lower energies. This suggests a fundamental complexity of the multiparticle phenomena and offers new materials for further development of theoretical investigations. In the same period, studies of constituent (quark-gluon) structure of hadrons had also been develped. Nowadays, pysicists believe that the quantum chromodynamics (QCD) is the fundamental law of the hadronic world. Multiparticle dynamics should also be described by QCD. We have known that the hard-jet phenomena are well explained by the perturbative QCD. On the other hand, the soft processes are considered to be non-perturbative phenomena which have not yet been solved, and related to the mechanism of the color confinement and formation of strings or color-flux tubes. Multiparticle production would offer useful information on this

  12. Spherical 3D photonic crystal with conducting nanoshell and particle core

    NASA Astrophysics Data System (ADS)

    Zamudio-Lara, A.; Sánchez-Mondragón, J.; Escobedo-Alatorre, J.; Pérez-Careta, E.; Torres-Cisneros, M.; Tecpoyotl-Torres, Margarita; Vázquez-Buenos Aires, O.

    2009-06-01

    We discuss a structured 3D Dielectric Photonic Crystal with both a metallic core and a metallic shell. We discuss the role of each one, the stack, the core as well as the cavity formed between the core and the shell. The low frequency metallic core features becomes much more significant as it gets smaller and get diluted by the cavity.

  13. Probing Enhanced Double-Strand Break Formation at Abasic Sites within Clustered Lesions in Nucleosome Core Particles.

    PubMed

    Banerjee, Samya; Chakraborty, Supratim; Jacinto, Marco Paolo; Paul, Michael D; Balster, Morgan V; Greenberg, Marc M

    2017-01-10

    DNA is rapidly cleaved under mild alkaline conditions at apyrimidinic/apurinic sites, but the half-life is several weeks in phosphate buffer (pH 7.5). However, abasic sites are ∼100-fold more reactive within nucleosome core particles (NCPs). Histone proteins catalyze the strand scission, and at superhelical location 1.5, the histone H4 tail is largely responsible for the accelerated cleavage. The rate constant for strand scission at an abasic site is enhanced further in a nucleosome core particle when it is part of a bistranded lesion containing a proximal strand break. Cleavage of this form results in a highly deleterious double-strand break. This acceleration is dependent upon the position of the abasic lesion in the NCP and its structure. The enhancement in cleavage rate at an apurinic/apyrimidinic site rapidly drops off as the distance between the strand break and abasic site increases and is negligible once the two forms of damage are separated by 7 bp. However, the enhancement of the rate of double-strand break formation increases when the size of the gap is increased from one to two nucleotides. In contrast, the cleavage rate enhancement at 2-deoxyribonolactone within bistranded lesions is more modest, and it is similar in free DNA and nucleosome core particles. We postulate that the enhanced rate of double-strand break formation at bistranded lesions containing apurinic/apyrimidinic sites within nucleosome core particles is a general phenomenon and is due to increased DNA flexibility.

  14. Composition of Individual Particles in the Wakes of an Athena II Rocket and the Space Shuttle

    NASA Astrophysics Data System (ADS)

    Cziczo, D. J.; Murphy, D. M.; Thomson, D. S.; Ross, M. N.

    2002-12-01

    The NOAA Particle Analysis by Laser Mass Spectrometry (PALMS) instrument was used to obtain the first in situ measurements of the composition of particles in the exhaust wakes of launch vehicles powered by solid rocket motors (SRMs). PALMS, mounted in the nose of a NASA WB-57F research aircraft, acquired mass spectra of over 2300 individual exhaust particles during stratospheric encounters with the plumes of an Athena II rocket and the Space Shuttle. The majority of positive mass spectra indicated the presence of Al, Fe, Ca, Na, and K, all primary or trace components of the aluminum fuel or the combustion catalyst. Organic material, presumably from combustion of binding and curing agents, was another common feature. Negative mass spectra showed Cl from the oxidizer, ammonium perchlorate, as well as aluminum oxide produced during combustion. Nitrate and phosphate fragments and water complexes were common features of spectra acquired during the Space Shuttle but not the Athena II plume intercepts. Elemental carbon (EC) was a significant particle type observed in the Athena II plume but not the Space Shuttle. The data show that the composition of particles emitted by SRMs are more diverse, more varied from rocket to rocket, and possibly more reactive than previously considered.

  15. Glass-NiP-CoFeP triplex-shell particles with hollow cores and tunable magnetic properties.

    PubMed

    An, Zhenguo; Zhang, Jingjie

    2013-02-01

    Low density (0.55-0.92g/mL, depending on the shell thickness and composition) glass-metal-metal triplex-shell hollow particles (TSHP) were prepared by a three-step route. First, micrometer-sized silicate glass particles with hollow cores, uniform shells, and high sphericity were prepared through spray drying and subsequent melting. NiP shell was uniformly assembled to the previously obtained glass hollow particles by silver seed induced chemical reduction of Ni(2+) by sodium hypophosphite, and glass-NiP double-shell hollow particles (DSHP) with compact and uniform shells were formed. The as-formed NiP particles further acted as the seeds for the directed formation and assembly of the CoFeP shell on the NiP shell to form the final glass-NiP-CoFeP triplex-shell hollow particles (TSHP). The influences of the component of the reaction system on the composition, structure, and magnetic properties of the hollow particles were studied. The multishell hollow particles thus obtained may have some promising applications in the fields of low-density magnetic materials, conduction, microwave absorbers, catalysis, etc. This work provides an additional strategy to fabricate multishell structured hollow particles with tailored shell composition and magnetic properties, which can be extended to the controlled preparation of multishell composite particles with the shells consisting of metal, oxides, or other compounds.

  16. Nuclear structure and the fate of core collapse (Type II) supernova

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2014-08-01

    For a long time Gerry Brown and his collaborator Hans Bethe considered the question of the final fate of a core collapse (Type II) supernova. Recalling ideas from nuclear structure on Kaon condensate and a soft equation of state of the dense nuclear matter they concluded that progenitor stars with mass as low as 17-18M⊙ (including supernova 1987A) could collapse to a small mass black hole with a mass just beyond 1.5M⊙, the upper bound they derive for a neutron star. We discuss another nuclear structure effect that determines the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also determines the fate of a Type II supernova with a carbon rich progenitor star producing a neutron star and oxygen rich collapsing to a black hole. While the C/O ratio is one of the most important nuclear inputs to stellar evolution it is still not known with sufficient accuracy. We discuss future efforts to measure with gamma-beam and TPC detector of the C12(α,γ)O16 reaction that determines the C/O ratio in stellar helium burning.

  17. Fuzzy ternary particle systems by surface-initiated atom transfer radical polymerization from layer-by-layer colloidal core-shell macroinitiator particles.

    PubMed

    Fulghum, Timothy M; Patton, Derek L; Advincula, Rigoberto C

    2006-09-26

    We report the synthesis of ternary polymer particle material systems composed of (a) a spherical colloidal particle core, coated with (b) a polyelectrolyte intermediate shell, and followed by (c) a grafted polymer brush prepared by surface-initiated polymerization as the outer shell. The layer-by-layer (LbL) deposition process was utilized to create a functional intermediate shell of poly(diallyl-dimethylammonium chloride)/poly(acrylic acid) multilayers on the colloid template with the final layer containing an atom transfer radical polymerization (ATRP) macroinitiator polyelectrolyte. The intermediate core-shell architecture was analyzed with FT-IR, electrophoretic mobililty (zeta-potential) measurements, atomic force microscopy, and transmission electron microscopy (TEM) techniques. The particles were then utilized as macroinitiators for the surface-initiated ATRP grafting process for poly(methyl methacrylate) polymer brush. The polymer grafting was confirmed with thermo gravimetric analysis, FT-IR, and TEM. The polymer brush formed the outermost shell for a ternary colloidal particle system. By combining the LbL and surface-initiated ATRP methods to produce controllable multidomain core-shell architectures, interesting functional properties should be obtainable based on independent polyelectrolyte and polymer brush behavior.

  18. Internal stresses in pre-stressed micron-scale aluminum core-shell particles and their improved reactivity

    NASA Astrophysics Data System (ADS)

    Levitas, Valery I.; McCollum, Jena; Pantoya, Michelle L.; Tamura, Nobumichi

    2015-09-01

    Dilatation of aluminum (Al) core for micron-scale particles covered by alumina (Al2O3) shell was measured utilizing x-ray diffraction with synchrotron radiation for untreated particles and particles after annealing at 573 K and fast quenching at 0.46 K/s. Such a treatment led to the increase in flame rate for Al + CuO composite by 32% and is consistent with theoretical predictions based on the melt-dispersion mechanism of reaction for Al particles. Experimental results confirmed theoretical estimates and proved that the improvement of Al reactivity is due to internal stresses. This opens new ways of controlling particle reactivity through creating and monitoring internal stresses.

  19. Internal stresses in pre-stressed micron-scale aluminum core-shell particles and their improved reactivity

    SciTech Connect

    Levitas, Valery I.; McCollum, Jena; Pantoya, Michelle L.; Tamura, Nobumichi

    2015-09-07

    Dilatation of aluminum (Al) core for micron-scale particles covered by alumina (Al{sub 2}O{sub 3}) shell was measured utilizing x-ray diffraction with synchrotron radiation for untreated particles and particles after annealing at 573 K and fast quenching at 0.46 K/s. Such a treatment led to the increase in flame rate for Al + CuO composite by 32% and is consistent with theoretical predictions based on the melt-dispersion mechanism of reaction for Al particles. Experimental results confirmed theoretical estimates and proved that the improvement of Al reactivity is due to internal stresses. This opens new ways of controlling particle reactivity through creating and monitoring internal stresses.

  20. Characterization of a purified photosystem II-phycobilisome particle preparation from Porphyridium cruentum

    SciTech Connect

    Chereskin, B.M.; Clement-Metral, J.D.; Gantt, E.

    1985-01-01

    Detergent preparations isolated from thylakoids of the red alga Porphyridium cruentum, in a sucrose, phosphate, citrate, magnesium chloride medium consist of phycobilisomes and possess high rates of photosystem II activity. Characterization of these particles shows that the O/sub 2/-evolving activity is stable for several hours and the pH optimum is about 6.5 to 7.2. Response of the system to light, electron donors and acceptors, and inhibitors verify that the observed activity, measured both as O/sub 2/ evolution and 2,6-dichlorophenol-indophenol reduction, is due to photosystem II. Furthermore, photosystem II is functionally coupled to the phycobilisome in this preparation since green light, absorbed by phycobilisomes of P. cruentum, is effective in promoting both O/sub 2/ evolution and 2,6-dichlorophenol-indophenol reduction. Photosystem II activity declines when light with wavelengths shorter than 665 nm is removed. Both 3-(3,4-dichlorophenyl)-1,1-dimethylurea and atrazine inhibit photosystem II activity in this preparation, indicating that the herbicide binding site is a component of the photosystem II-phycobilisome particle. 24 references, 4 figures, 2 tables.

  1. Nonhistone nuclear high mobility group proteins 14 and 17 stabilize nucleosome core particles

    SciTech Connect

    Paton, A.E.; Wilkinson-Singley, E.; Olins, D.W.

    1983-11-10

    Nucleosome core particles form well defined complexes with the nuclear nonhistone proteins HMG 14 or 17. The binding of HMG 14 or 17 to nucleosomes results in greater stability of the nucleosomal DNA as shown by circular dichroism and thermal denaturation. Under appropriate conditions the binding is cooperative, and cooperativity is ionic strength dependent. The specificity and cooperative transitions of high mobility group (HMG) binding are preserved in 1 M urea. Specificity is lost in 4 M urea. Thermal denaturation and circular dichroism show a dramatic reversal of the effects of urea on nucleosomes when HMG 14 or 17 is bound, indicating stabilization of the nucleosome by HMG proteins. Complexes formed between reconstructed nucleosomes containing purified inner histones plus poly (dA-dT) and HMG 14 or 17 demonstrate that the HMG binding site requires only DNA and histones. Electron microscopy reveals no major structural alterations in the nucleosome upon binding of HMG 14 or 17. Cross-linking the nucleosome extensively with formaldehyde under cooperative HMG binding conditions does not prevent the ionic strength-dependent shift to noncooperative binding. This suggests mechanisms other than internal nucleosome conformational changes may be involved in cooperative HMG binding.

  2. 3D simulations of young core-collapse supernova remnants undergoing efficient particle acceleration

    NASA Astrophysics Data System (ADS)

    Ferrand, Gilles; Safi-Harb, Samar

    2016-06-01

    Within our Galaxy, supernova remnants are believed to be the major sources of cosmic rays up to the 'knee'. However important questions remain regarding the share of the hadronic and leptonic components, and the fraction of the supernova energy channelled into these components. We address such question by the means of numerical simulations that combine a hydrodynamic treatment of the shock wave with a kinetic treatment of particle acceleration. Performing 3D simulations allows us to produce synthetic projected maps and spectra of the thermal and non-thermal emission, that can be compared with multi-wavelength observations (in radio, X-rays, and γ-rays). Supernovae come in different types, and although their energy budget is of the same order, their remnants have different properties, and so may contribute in different ways to the pool of Galactic cosmic-rays. Our first simulations were focused on thermonuclear supernovae, like Tycho's SNR, that usually occur in a mostly undisturbed medium. Here we present our 3D simulations of core-collapse supernovae, like the Cas A SNR, that occur in a more complex medium bearing the imprint of the wind of the progenitor star.

  3. Fabrication and characterization of flaky core-shell particles by magnetron sputtering silver onto diatomite

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Zhang, Deyuan; Cai, Jun

    2016-02-01

    Diatomite has delicate porous structures and various shapes, making them ideal templates for microscopic core-shell particles fabrication. In this study, a new process of magnetron sputtering assisted with photoresist positioning was proposed to fabricate lightweight silver coated porous diatomite with superior coating quality and performance. The diatomite has been treated with different sputtering time to investigate the silver film growing process on the surface. The morphologies, constituents, phase structures and surface roughness of the silver coated diatomite were analyzed with SEM, EDS, XRD and AFM respectively. The results showed that the optimized magnetron sputtering time was 8-16 min, under which the diatomite templates were successfully coated with uniform silver film, which exhibits face centered cubic (fcc) structure, and the initial porous structures were kept. Moreover, this silver coating has lower surface roughness (RMS 4.513 ± 0.2 nm) than that obtained by electroless plating (RMS 15.692 ± 0.5 nm). And the infrared emissivity of coatings made with magnetron sputtering and electroless plating silver coated diatomite can reach to the lowest value of 0.528 and 0.716 respectively.

  4. Investigation of high velocity separator for particle removal in coal gasification plants. Phase II report

    SciTech Connect

    Linhardt, H.D.

    1980-01-15

    This report summarizes the results of Phase II of the High Velocity Particle Separator Program performed under Contract EF-77-C-01-2709. This high velocity wedge separator has the potential to reduce equipment size and cost of high temperature and pressurized particulate removal equipment for coal derived gases. Phase II has been directed toward testing and detailed conceptual design of an element suitable for a commercial scale high temperature, high pressure particle separator (HTPS). Concurrently, Phase IA has been conducted, which utilized the ambient analog method (AAM) for aerodynamic and collection performance investigation of each HTPS configuration prior and during hot testing. This report summarizes the results of Phase IA and II. The AAM effort established correlation of theoretical analysis and experiment for HTPS pressure drop, purge flow ratio and collection efficiency potential. Task I defined the initial test conditions to be the contract design point of 1800/sup 0/F and 350 psia. The 1800/sup 0/F, 350 psia testing represents the main high temperature testing with coal-derived particulates in the 2 to 10 micron range. Phase IA and Phase II have demonstrated efficient particle collection with acceptable pressure drop. In view of these encouraging results, it is reasonable to apply the developed technology toward future hot gas particulate cleanup requirements.

  5. Relationship between polycyclic aromatic hydrocarbons (PAHs) and particle size in dated core sediments in Lake Lianhuan, Northeast China.

    PubMed

    Sun, Li; Zang, Shuying

    2013-09-01

    Atmospheric particle associated with pyrogenic polycyclic aromatic hydrocarbons (PAHs) poses serious threats to human health by inhalation exposure, especially in semiarid areas. Hence, the distributions of PAHs and particle size in two core sediments collected from Lake Lianhuan, Northeast China were studied. The sediments were dated radiometrically, and particle size distribution and PAH concentration were evaluated and potential human health risk was assessed. From 1980 to 2007, the dominant PAHs in the two cores were 2- and 3-ring PAHs, and the concentrations of 3-6 ring PAHs gradually increased from the early 1990s. Diagnostic ratios indicated that pyrogenic PAHs were the main sources of PAHs which changed over time from combustions of wood and coal to liquid fossil fuel sources. Fine particles (<65 μm) were the predominant particle size (56-97%). Lacustrine source (with the peak towards 200-400 μm) and eolian sources derived from short (2.0-10 and 30-65 μm) and long (0.4-1.0 μm) distance suspension were indentified from frequency distribution pattern of particle size. Significant correlations between 3-6 ring PAHs (especially carcinogenic 5-6 ring PAHs) and 10-35 μm particulate fractions indicated that eolian particles played an important role in adsorbing pyrogenic PAHs. Petroleum source of PAHs was only identified during the 1980s in one core sediments, in which positive correlations between 2-ring PAHs and particulate fractions of >125 μm were found. Future research should focus on the seven carcinogenic pyrogenic PAHs due to a rapidly increasing trend since 1995 based on the assessment of toxic equivalency factors.

  6. Fabrication of quantum dot/silica core-shell particles immobilizing Au nanoparticles and their dual imaging functions

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yoshio; Matsudo, Hiromu; Li, Ting-ting; Shibuya, Kyosuke; Kubota, Yohsuke; Oikawa, Takahiro; Nakagawa, Tomohiko; Gonda, Kohsuke

    2016-03-01

    The present work proposes preparation methods for quantum dot/silica (QD/SiO2) core-shell particles that immobilize Au nanoparticles (QD/SiO2/Au). A colloid solution of QD/SiO2 core-shell particles with an average size of 47.0 ± 6.1 nm was prepared by a sol-gel reaction of tetraethyl orthosilicate in the presence of the QDs with an average size of 10.3 ± 2.1 nm. A colloid solution of Au nanoparticles with an average size of 17.9 ± 1.3 nm was prepared by reducing Au3+ ions with sodium citrate in water at 80 °C. Introduction of amino groups to QD/SiO2 particle surfaces was performed using (3-aminopropyl)-triethoxysilane (QD/SiO2-NH2). The QD/SiO2/Au particles were fabricated by mixing the Au particle colloid solution and the QD/SiO2-NH2 particle colloid solution. Values of radiant efficiency and computed tomography for the QD/SiO2/Au particle colloid solution were 2.23 × 107 (p/s/cm2/sr)/(μW/cm2) at a QD concentration of 8 × 10-7 M and 1180 ± 314 Hounsfield units and an Au concentration of 5.4 × 10-2 M. The QD/SiO2/Au particle colloid solution was injected into a mouse chest wall. Fluorescence emitted from the colloid solution could be detected on the skin covering the chest wall. The colloid solution could also be X-ray-imaged in the chest wall. Consequently, the QD/SiO2/Au particle colloid solution was found to have dual functions, i.e., fluorescence emission and X-ray absorption in vivo, which makes the colloid solution suitable to function as a contrast agent for dual imaging processes.

  7. A disulfide-bonded dimer of the core protein of hepatitis C virus is important for virus-like particle production.

    PubMed

    Kushima, Yukihiro; Wakita, Takaji; Hijikata, Makoto

    2010-09-01

    Hepatitis C virus (HCV) core protein forms the nucleocapsid of the HCV particle. Although many functions of core protein have been reported, how the HCV particle is assembled is not well understood. Here we show that the nucleocapsid-like particle of HCV is composed of a disulfide-bonded core protein complex (dbc-complex). We also found that the disulfide-bonded dimer of the core protein (dbd-core) is formed at the endoplasmic reticulum (ER), where the core protein is initially produced and processed. Mutational analysis revealed that the cysteine residue at amino acid position 128 (Cys128) of the core protein, a highly conserved residue among almost all reported isolates, is responsible for dbd-core formation and virus-like particle production but has no effect on the replication of the HCV RNA genome or the several known functions of the core protein, including RNA binding ability and localization to the lipid droplet. The Cys128 mutant core protein showed a dominant negative effect in terms of HCV-like particle production. These results suggest that this disulfide bond is critical for the HCV virion. We also obtained the results that the dbc-complex in the nucleocapsid-like structure was sensitive to proteinase K but not trypsin digestion, suggesting that the capsid is built up of a tightly packed structure of the core protein, with its amino (N)-terminal arginine-rich region being concealed inside.

  8. North and equatorial Pacific Ocean circulation in the CORE-II hindcast simulations

    NASA Astrophysics Data System (ADS)

    Tseng, Yu-heng; Lin, Hongyang; Chen, Han-ching; Thompson, Keith; Bentsen, Mats; Böning, Claus W.; Bozec, Alexandra; Cassou, Christophe; Chassignet, Eric; Chow, Chun Hoe; Danabasoglu, Gokhan; Danilov, Sergey; Farneti, Riccardo; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Ilicak, Mehmet; Jung, Thomas; Masina, Simona; Navarra, Antonio; Patara, Lavinia; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Sui, Chung-Hsiung; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Yeager, Steve G.

    2016-08-01

    We evaluate the mean circulation patterns, water mass distributions, and tropical dynamics of the North and Equatorial Pacific Ocean based on a suite of global ocean-sea ice simulations driven by the CORE-II atmospheric forcing from 1963-2007. The first three moments (mean, standard deviation and skewness) of sea surface height and surface temperature variability are assessed against observations. Large discrepancies are found in the variance and skewness of sea surface height and in the skewness of sea surface temperature. Comparing with the observation, most models underestimate the Kuroshio transport in the Asian Marginal seas due to the missing influence of the unresolved western boundary current and meso-scale eddies. In terms of the Mixed Layer Depths (MLDs) in the North Pacific, the two observed maxima associated with Subtropical Mode Water and Central Mode Water formation coalesce into a large pool of deep MLDs in all participating models, but another local maximum associated with the formation of Eastern Subtropical Mode Water can be found in all models with different magnitudes. The main model bias of deep MLDs results from excessive Subtropical Mode Water formation due to inaccurate representation of the Kuroshio separation and of the associated excessively warm and salty Kuroshio water. Further water mass analysis shows that the North Pacific Intermediate Water can penetrate southward in most models, but its distribution greatly varies among models depending not only on grid resolution and vertical coordinate but also on the model dynamics. All simulations show overall similar large scale tropical current system, but with differences in the structures of the Equatorial Undercurrent. We also confirm the key role of the meridional gradient of the wind stress curl in driving the equatorial transport, leading to a generally weak North Equatorial Counter Current in all models due to inaccurate CORE-II equatorial wind fields. Most models show a larger

  9. The Electronic Structure of CdSe/CdS Core/Shell Seeded Nanorods: Type-I or Quasi-Type-II?

    PubMed Central

    2013-01-01

    The electronic structure of CdSe/CdS core/shell seeded nanorods of experimentally relevant size is studied using a combination of molecular dynamics and semiempirical pseudopotential techniques with the aim to address the transition from type-I to a quasi-type-II band alignment. The hole is found to be localized in the core region regardless of its size. The overlap of the electron density with the core region depends markedly on the size of the CdSe core. For small cores, we observe little overlap, consistent with type-II behavior. For large cores, significant core-overlap of a number of excitonic states can lead to type-I behavior. When electron–hole interactions are taken into account, the core-overlap is further increased. Our calculations indicate that the observed transition from type-II to type-I is largely due to simple volume effects and not to band alignment. PMID:24215466

  10. Protein film voltammetry and co-factor electron transfer dynamics in spinach photosystem II core complex.

    PubMed

    Zhang, Yun; Magdaong, Nikki; Frank, Harry A; Rusling, James F

    2014-05-01

    Direct protein film voltammetry (PFV) was used to investigate the redox properties of the photosystem II (PSII) core complex from spinach. The complex was isolated using an improved protocol not used previously for PFV. The PSII core complex had high oxygen-evolving capacity and was incorporated into thin lipid and polyion films. Three well-defined reversible pairs of reduction and oxidation voltammetry peaks were observed at 4 °C in the dark. Results were similar in both types of films, indicating that the environment of the PSII-bound cofactors was not influenced by film type. Based on comparison with various control samples including Mn-depleted PSII, peaks were assigned to chlorophyll a (Chl a) (Em = -0.47 V, all vs. NHE, at pH 6), quinones (-0.12 V), and the manganese (Mn) cluster (Em = 0.18 V). PFV of purified iron heme protein cytochrome b-559 (Cyt b-559), a component of PSII, gave a partly reversible peak pair at 0.004 V that did not have a potential similar to any peaks observed from the intact PSII core complex. The closest peak in PSII to 0.004 V is the 0.18 V peak that was found to be associated with a two-electron process, and thus is inconsistent with iron heme protein voltammetry. The -0.47 V peak had a peak potential and peak potential-pH dependence similar to that found for purified Chl a incorporated into DMPC films. The midpoint potentials reported here may differ to various extents from previously reported redox titration data due to the influence of electrode double-layer effects. Heterogeneous electron transfer (hET) rate constants were estimated by theoretical fitting and digital simulations for the -0.47 and 0.18 V peaks. Data for the Chl a peaks were best fit to a one-electron model, while the peak assigned to the Mn cluster was best fit by a two-electron/one-proton model.

  11. Wetting on fractal superhydrophobic surfaces from "core-shell" particles: a comparison of theory and experiment.

    PubMed

    Synytska, Alla; Ionov, Leonid; Grundke, Karina; Stamm, Manfred

    2009-03-03

    We report an experimental and theoretical investigation of the wetting behavior of different model polar and nonpolar liquids and their mixtures on superhydrophobic fractal surfaces made of polymer- or silane-coated "core-shell" particles. We compared the experimental results with the theoretical predictions made according to the theories of Onda-Shibuichi (describes wetting on fractal surfaces) and Cassie-Baxter (describes wetting on generic rough composite surfaces). We found that the experimental findings deviate from the behavior predicted by the Onda-Shibuichi model. On the other hand, the wetting properties were found to be close to the predictions made by the Cassie-Baxter model in the hydrophobic region (the intrinsic contact angle on the flat surface is larger than 90 degrees). However, the wetting behavior in the hydrophilic region (the intrinsic contact angle is less than 90 degrees) could not be described by the Onda-Shibuichi or Cassie-Baxter model. The observed inconsistency between the experimental results and theoretical predictions was explained by the formation of metastable states of a liquid droplet on a fabricated fractal surface according to the theory developed by Johnson and Dettre for generic rough surfaces. The entrapments of the liquid droplets in metastable states resulted in superhydrophobic behavior on fractal surfaces as well, made from nonfluorinated material such as polystyrene with a surface free energy of about 30 mJ/m2. This finding is very promising for real industrial applications where fluorinated compounds are willing to be reduced. It can be concluded that employing a texture with fractal geometry is necessary for the design of superhydrophobic coatings. Thereby, extremely lowering the surface free energy of materials by fluorination is not an obligatory factor for the generation of liquid-repellent superhydrophobic materials. We believe that the results we presented in the paper give new insight into the understanding of

  12. Structural Flexibility of the Nucleosome Core Particle at Atomic Resolution studied by Molecular Dynamics Simulation.

    SciTech Connect

    Roccatano, Danilo; Barthel, Andre; Zacharias, Martin W.

    2007-01-24

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Comparative explicit solvent molecular dynamics (MD) simulations have been performed on a complete nucleosome core particle with and without N-terminal histone tails for more than 20 ns. Main purpose of the simulations was to study the dynamics of mobile elements such as histone N-terminal tails and how packing and DNA-bending influences the fine structure and dynamics of DNA. Except for the tails, histone and DNA molecules stayed on average close to the crystallographic start structure supporting the quality of the current force field approach. Despite the packing strain, no increase of transitions to noncanonical nucleic acid backbone conformations compared to regular B-DNA was observed. The pattern of kinks and bends along the DNA remained close to the experiment overall. In addition to the local dynamics, the simulations allowed the analysis of the superhelical mobility indicating a limited relative mobility of DNA segments separated by one superhelical turn (mean relative displacement of approximately 60.2 nm, mainly along the superhelical axis). An even higher rigidity was found for relative motions (distance fluctuations) of segments separated by half a superhelical turn (approximately 60.1 nm). The N-terminal tails underwent dramatic conformational rearrangements on the nanosecond time scale toward partially and transiently wrapped states around the DNA. Many of the histone tail changes corresponded to coupled association and folding events from fully solvent-exposed states toward complexes with the major and minor grooves of DNA. The simulations indicate that the rapid conformational changes of the tails can modulate the DNA accessibility within a few nanoseconds. # 2007

  13. Performance of plasma opening switches for the Particle Beam Fusion Accelerator II (PBFA II)

    SciTech Connect

    Rochau, G.E.; McDaniel, D.H.; Mendel, C.W.; Sweeney, M.A.; Moore, W.B.S.; Mowrer, G.R.; Simpson, W.W.; Zagar, D.M.; Grasser, T.; McDougal, C.D.

    1989-01-01

    During 1987 and 1988, Plasma Opening Switch (POS) experiments have been continued with the goal of providing voltage and power gain on the PBFA II ion beam accelerator at Sandia National Laboratories. The experiments have developed a POS that has a rugged plasma source, will open rapidly, and will couple to a high-impedance load. The initial erosion switch design with improved plasma uniformity does not couple to these loads. Therefore, we have abandoned further development of this switch for voltage and power gain. Three alternate designs have been developed, tested, and are found to have better performance with the high-impedance loads. These new switches employ magnetic fields to control and confine the injected plasma. A summary of the switch configurations, their theory of operation, and the experimental results is presented and discussed. 4 refs., 10 figs.

  14. On the extent of size range and power law scaling for particles of natural carbonate fault cores

    NASA Astrophysics Data System (ADS)

    Billi, Andrea

    2007-09-01

    To determine the size range and both type and extent of the scaling laws for particles of loose natural carbonate fault rocks, six granular fault cores from Mesozoic carbonate strata of central Italy were sampled. Particle size distributions of twelve samples were determined by combining sieving and sedimentation methods. Results show that, regardless of the fault geometry, kinematics, and tectonic history, the size of fault rock particles respects a power law distribution across approximately four orders of magnitude. The fractal dimension ( D) of the particle size distribution in the analysed samples ranges between ˜2.0 and ˜3.5. A lower bound to the power law trend is evident in all samples except in those with the highest D-values; in these samples, the smallest analysed particles (˜0.0005 mm in diameter) were also included in the power law interval, meaning that the lower size limit of the power law distribution decreases for increasing D-values and that smallest particles start to be comminuted with increasing strain (i.e. increasing fault displacement and D-values). For increasing D-values, also the largest particles tends to decrease in number, but this evidence may be affected by a censoring bias connected with the sample size. Stick-slip behaviour is suggested for the studied faults on the basis of the inferred particle size evolutions. Although further analyses are necessary to make the results of this study more generalizable, the preliminary definition of the scaling rules for fault rock particles may serve as a tool for predicting a large scale of fault rock particles once a limited range is known. In particular, data from this study may result useful as input numbers in numerical models addressing the packing of fault rock particles for frictional and hydraulic purposes.

  15. Synthesis and Characterization of Monodisperse Metallodielectric SiO2@Pt@SiO2 Core-Shell-Shell Particles.

    PubMed

    Petrov, Alexey; Lehmann, Hauke; Finsel, Maik; Klinke, Christian; Weller, Horst; Vossmeyer, Tobias

    2016-01-26

    Metallodielectric nanostructured core-shell-shell particles are particularly desirable for enabling novel types of optical components, including narrow-band absorbers, narrow-band photodetectors, and thermal emitters, as well as new types of sensors and catalysts. Here, we present a facile approach for the preparation of submicron SiO2@Pt@SiO2 core-shell-shell particles. As shown by transmission and scanning electron microscopy, the first steps of this approach allow for the deposition of closed and almost perfectly smooth platinum shells onto silica cores via a seeded growth mechanism. By choosing appropriate conditions, the shell thickness could be adjusted precisely, ranging from ∼3 to ∼32 nm. As determined by X-ray diffraction, the crystalline domain sizes of the polycrystalline metal shells were ∼4 nm, regardless of the shell thickness. The platinum content of the particles was determined by atomic absorption spectroscopy and for thin shells consistent with a dense metal layer of the TEM-measured thickness. In addition, we show that the roughness of the platinum shell strongly depends on the storage time of the gold seeds used to initiate reductive platinum deposition. Further, using polyvinylpyrrolidone as adhesion layer, it was possible to coat the metallic shells with very homogeneous and smooth insulating silica shells of well-controlled thicknesses between ∼2 and ∼43 nm. After depositing the particles onto silicon substrates equipped with interdigitated electrode structures, the metallic character of the SiO2@Pt particles and the insulating character of the SiO2 shells of the SiO2@Pt@SiO2 particles were successfully demonstrated by charge transport measurements at variable temperatures.

  16. Atlantic-Arctic exchange in a series of ocean model simulations (CORE-II)

    NASA Astrophysics Data System (ADS)

    Roth, Christina; Behrens, Erik; Biastoch, Arne

    2014-05-01

    In this study we aim to improve the understanding of exchange processes between the North Atlantic and the Arctic Ocean. The Nordic Sea builds an important connector between these regions, by receiving and modifying warm and saline Atlantic waters, and by providing dense overflow as a backbone of the Atlantic Meridional Overturning Circulation (AMOC). Using a hierarchy of global ocean/sea-ice models, the specific role of the Nordic Seas, both providing a feedback with the AMOC, but also as a modulator of the Atlantic water flowing into the Arctic Ocean, is examined. The models have been performed under the CORE-II protocol, in which atmospheric forcing of the past 60 years was applied in a subsequent series of 5 iterations. During the course of this 300-year long integration, the AMOC shows substantial changes, which are correlated with water mass characteristics in the Denmark Strait overflow characteristics. Quantitative analyses using Lagrangian trajectories explore the impact of these trends on the Arctic Ocean through the Barents Sea and the Fram Strait.

  17. Preparation and characterization of inorganic-organic trilayer core-shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles

    NASA Astrophysics Data System (ADS)

    Bai, Ruiqin; Qiu, Teng; Han, Feng; He, Lifan; Li, Xiaoyu

    2012-07-01

    The inorganic-organic trilayer core-shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared via seeded emulsion polymerization of acrylate monomers and octamethylcyclotetrasiloxane (D4) gradually, using functional polymethacryloxypropylsilsesquioxane (PSQ) latex particles with reactive methacryloxypropyl groups synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane in the presence of mixed emulsifiers as seeds. The FTIR spectra show that acrylate monomers and D4 are effectively involved in the emulsion copolymerization and formed the polydimethylsiloxane-containing hybrid latex particles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirm that the resultant hybrid latex particles have evident trilayer core-shell structure and a narrow size distribution. XPS analysis also indicates that polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared and PDMS is rich in the surface of the hybrid latex film. Additionally, compared with the hybrid latex film without PDMS, the hybrid latex film containing PDMS shows higher hydrophobicity (water contact angle) and lower water absorption.

  18. Modeling Lost-Particle Backgrounds in PEP-II Using LPTURTLE

    SciTech Connect

    Fieguth, T.; Barlow, R.; Kozanecki, W.; /DAPNIA, Saclay

    2005-05-17

    Background studies during the design, construction, commissioning, operation and improvement of BaBar and PEP-II have been greatly influenced by results from a program referred to as LPTURTLE (Lost Particle TURTLE) which was originally conceived for the purpose of studying gas background for SLC. This venerable program is still in use today. We describe its use, capabilities and improvements and refer to current results now being applied to BaBar.

  19. Generation of nano-sized core-shell particles using a coaxial tri-capillary electrospray-template removal method.

    PubMed

    Cao, Lihua; Luo, Jun; Tu, Kehua; Wang, Li-Qun; Jiang, Hongliang

    2014-03-01

    This study proposed a new strategy based on a coaxial tri-capillary electrospray-template removal process for producing nanosized polylactide-b-polyethylene glycol (PLA-PEG) particles with a core-shell structure. Microparticles with core-shell-corona structures were first fabricated by coaxial tri-capillary electrospray, and core-shell nanoparticles less than 200 nm in size were subsequently obtained by removing the PEG template from the core-shell-corona microparticles. The nanoparticle size could be modulated by adjusting the flow rate of corona fluid, and nanoparticles with an average diameter of 106±5 nm were obtained. The nanoparticles displayed excellent dispersion stability in aqueous media and very low cytotoxicity. Paclitaxel was used as a model drug to be incorporated into the core section of the nanoparticles. A drug loading content in the nanoparticles as high as 50.7±1.5 wt% with an encapsulation efficiency of greater than 70% could be achieved by simply increasing the feed rate of the drug solution. Paclitaxel exhibited sustained release from the nanoparticles for more than 40 days. The location of the paclitaxel in the nanoparticles, i.e., in the core or shell layer, did not have a significant effect on its release.

  20. Host cellular annexin II is associated with cytomegalovirus particles isolated from cultured human fibroblasts.

    PubMed Central

    Wright, J F; Kurosky, A; Pryzdial, E L; Wasi, S

    1995-01-01

    A significant amount of host cellular annexin II was found to be associated with human cytomegalovirus isolated from cultured human fibroblasts (approximately 1,160 molecules per virion). This composition was established by four different analytical approaches that included (i) Western blot (immunoblot) analysis of gradient-purified virions with a monoclonal antibody specific for annexin II, (ii) peptide mapping and sequence analysis of virus-associated proteins and proteins dissociated from virus following EDTA treatment, (iii) electron microscopic immunocytochemistry of gradient-purified virions, and (iv) labeling of virus-associated proteins by lactoperoxidase-catalyzed radioiodination. These results indicated that annexin II was primarily localized to the viral surface, where it bound in a divalent cation-dependent manner. In functional experiments, a rabbit antiserum raised against annexin II inhibited cytomegalovirus plaque formation in human foreskin fibroblast monolayers in a concentration-dependent manner. Cumulatively, these studies demonstrate an association of host annexin II with cytomegalovirus particles and provide evidence for the involvement of this cellular protein in virus infectivity. PMID:7609045

  1. Self-assembled HCV core virus-like particles targeted and inhibited tumor cell migration and invasion

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Xu, Xuehe; Jin, Aihui; Jia, Qunying; Zhou, Huaibin; Kang, Shuai; Lou, Yongliang; Gao, Jimin; Lu, Jianxin

    2013-09-01

    We used a baculovirus expression system to express fusion proteins of HCV core, RGD (Arg-Gly-Asp) peptide, and IFN-α2a fragments in Sf9 cells. Western blotting and electron microscopy demonstrate that HCV core, peptides RGD, and IFN-α2a fusion proteins assemble into 30 to 40 nm nano-particles (virus-like particles, VLPs). Xenograft assays show that VLPs greatly reduced tumor volume and weight with regard to a nontreated xenograft. Migration and invasion results show that VLPs can inhibit the migration and invasion of the breast cancer cells MDA-MB231. This study will provide theoretical and experimental basis for the establishment of safe and effective tumor-targeted drug delivery systems and clinical application of VLPs carrying cell interacting cargo.

  2. Synthesis of TiO{sub 2} core/RuO{sub 2} shell particles using multistep ultrasonic spray pyrolysis

    SciTech Connect

    Stopic, Srecko; Friedrich, Bernd; Schroeder, Michael; Weirich, Thomas E.

    2013-09-01

    Graphical abstract: - Highlights: • TiO{sub 2} core/RuO{sub 2} shell submicron-particles were prepared via a sequential spray pyrolysis. • Spherical particles have the mean particle diameters between 200 and 400 nm. • This method is promising for synthesis of core–shell and core–multishell materials. - Abstract: Spherical submicron-particles with TiO{sub 2} core–RuO{sub 2} shell structure have been synthesized by employing sequential ultrasonic spray pyrolysis. The particles have been investigated by X-ray powder diffraction, scanning electron microscopy and different transmission electron microscopy techniques. The quality of the core–shell structure of the particles has been confirmed by comparison of the experimental data with those generated on the basis of a hard sphere core–shell model. It has been found that the mixing of the Ru-containing aerosol with the TiO{sub 2} particle stream has a significant impact on the core–shell formation. The method introduced in this study can probably be applied for preparation of core–shell and core–multishell materials that are difficult to synthesize in a single step spray pyrolysis process.

  3. Yield Optimisation of Hepatitis B Virus Core Particles in E. coli Expression System for Drug Delivery Applications.

    PubMed

    Bin Mohamed Suffian, Izzat Fahimuddin; Garcia-Maya, Mitla; Brown, Paul; Bui, Tam; Nishimura, Yuya; Palermo, Amir Rafiq Bin Mohammad Johari; Ogino, Chiaki; Kondo, Akihiko; Al-Jamal, Khuloud T

    2017-03-03

    An E. coli expression system offers a mean for rapid, high yield and economical production of Hepatitis B Virus core (HBc) particles. However, high-level production of HBc particles in bacteria is demanding and optimisation of HBc particle yield from E. coli is required to improve laboratory-scale productivity for further drug delivery applications. Production steps involve bacterial culture, protein isolation, denaturation, purification and finally protein assembly. In this study, we describe a modified E. coli based method for purifying HBc particles and compare the results with those obtained using a conventional purification method. HBc particle morphology was confirmed by Atomic Force Microscopy (AFM). Protein specificity and secondary structure were confirmed by Western Blot and Circular Dichroism (CD), respectively. The modified method produced ~3-fold higher yield and greater purity of wild type HBc particles than the conventional method. Our results demonstrated that the modified method produce a better yield and purity of HBc particles in an E. coli-expression system, which are fully characterised and suitable to be used for drug delivery applications.

  4. Yield Optimisation of Hepatitis B Virus Core Particles in E. coli Expression System for Drug Delivery Applications

    PubMed Central

    Bin Mohamed Suffian, Izzat Fahimuddin; Garcia-Maya, Mitla; Brown, Paul; Bui, Tam; Nishimura, Yuya; Palermo, Amir Rafiq Bin Mohammad Johari; Ogino, Chiaki; Kondo, Akihiko; Al-Jamal, Khuloud T.

    2017-01-01

    An E. coli expression system offers a mean for rapid, high yield and economical production of Hepatitis B Virus core (HBc) particles. However, high-level production of HBc particles in bacteria is demanding and optimisation of HBc particle yield from E. coli is required to improve laboratory-scale productivity for further drug delivery applications. Production steps involve bacterial culture, protein isolation, denaturation, purification and finally protein assembly. In this study, we describe a modified E. coli based method for purifying HBc particles and compare the results with those obtained using a conventional purification method. HBc particle morphology was confirmed by Atomic Force Microscopy (AFM). Protein specificity and secondary structure were confirmed by Western Blot and Circular Dichroism (CD), respectively. The modified method produced ~3-fold higher yield and greater purity of wild type HBc particles than the conventional method. Our results demonstrated that the modified method produce a better yield and purity of HBc particles in an E. coli-expression system, which are fully characterised and suitable to be used for drug delivery applications. PMID:28256592

  5. A core-shell structured nanocomposite material for detection, adsorption and removal of Hg(II) ions in water.

    PubMed

    Li, Le; Tang, Shuangyang; Ding, Dexin; Hu, Nan; Yang, Shengyuan; He, Shuya; Wang, Yongdong; Tan, Yan; Sun, Jing

    2012-11-01

    In this paper, a core-shell structured nanocomposite material was prepared for the detection, adsorption and removal of Hg(ll) ions in aqueous solution. The core was made from Fe3O4 nanoparticles with superparamagnetic behavior and the outer shell was made from amorphous silica modified with pyrene-based sensing-probes. The material could detect and adsorb Hg(II) ions in aqueous solution due to its surface being modified with pyrene-based sensing-probes, and could easily be removed from the solution by magnetic force because of its core being made from magnetic Fe3O4 nanoparticles. This multifunctional core-shell structure was confirmed and characterized by TEM, IR spectra, TGA, XRD and N2 adsorption/desorption isotherms. Experiments were conducted on its functions of detection, adsorption and removal of Hg(II) ions in aqueous solution. The experimental results showed that this composite material had high sensitivity and unique selectivity to Hg(II), and that it could easily be removed from the solution.

  6. Study of Particle Motion in He II Counterflow Across a Wide Heat Flux Range

    NASA Astrophysics Data System (ADS)

    Mastracci, Brian; Takada, Suguru; Guo, Wei

    2017-01-01

    Some discrepancy exists in the results of He II counterflow experiments obtained using particle image velocimetry (PIV) when compared with those obtained using particle tracking velocimetry (PTV): using PIV, it was observed that tracer particles move at roughly half the expected normal fluid velocity, v_n/2 , while tracer particles observed using PTV moved at approximately v_n . A suggested explanation is that two different flow regimes were examined since the range of heat flux applied in each experiment was adjacent but non-overlapping. Another PTV experiment attempted to test this model, but the applied heat flux did not overlap with any PIV experiments. We report on the beginnings of a study of solid D_2 particle motion in counterflow using PTV, and the heat flux range overlaps that of all previous visualization studies. The observed particle velocity distribution transitions from a two-peak structure to a single peak as the heat flux is increased. Furthermore, the mean value of one peak in the bi-modal distributions grows at approximately the same rate as v_n , while the mean value of the single-peak distributions grows at roughly 0.4v_n , in reasonable agreement with both previous experiments and with the suggested model.

  7. Production of rotavirus core-like particles in Sf9 cells using recombinase-mediated cassette exchange.

    PubMed

    Fernandes, Fabiana; Dias, Mafalda M; Vidigal, João; Sousa, Marcos F Q; Patrone, Marco; Teixeira, Ana P; Alves, Paula M

    2014-02-10

    A flexible Sf9 insect cell line was recently developed leveraging the recombinase-mediated cassette exchange (RMCE) technology, which competes with the popular baculovirus expression vector system (BEVS) in terms of speed to produce new proteins. Herein, the ability of this cell platform to produce complex proteins, such as rotavirus core-like particles, was evaluated. A gene construct coding for a VP2-GFP fusion protein was targeted to a pre-characterized high recombination efficiency locus flanked by flipase (Flp) recognition target sites and, after three weeks in selection, an isogenic cell population was obtained. Despite the lower cell specific productivities with respect to those obtained by baculovirus infection, the titers of VP2-GFP reached in shake flask batch cultures were comparable as a result of higher cell densities. To further improve the VP2-GFP levels from stable expression, analysis of exhausted medium was undertaken to design feeding strategies enabling higher cell densities as well as increased culture duration. The implementation of the best strategy allowed reaching 20 million cells per ml in bioreactor cultures; the integrity of the rotavirus core-like particles could be confirmed by electron microscopy. Overall, we show that this Sf9-Flp cell platform represents a valuable alternative to the BEVS for producing complex recombinant proteins, such as rotavirus core-like particles.

  8. Comparative and competitive adsorption of Pb(II) and Cu(II) using tetraethylenepentamine modified chitosan/CoFe2O4 particles.

    PubMed

    Fan, Chunzhen; Li, Kan; Li, Juexiu; Ying, Diwen; Wang, Yalin; Jia, Jinping

    2017-03-15

    In this paper, tetraethylenepentamine (TEPA) modified chitosan/CoFe2O4 particles were prepared for comparative and competitive adsorption of Cu(II) and Pb(II) in single and bi-component aqueous solutions. The characteristics results of SEM, FTIR and XRD indicated that the adsorbent was successfully fabricated. The magnetic property results manifested that the particles with saturation magnetization value of 63.83emug(-1) would have a fast magnetic response. The effects of experimental parameters including contact time, pH value, initial metal ions concentration and coexisting ions on single and bi-component adsorption were investigated. The results revealed that the adsorption kinetic was followed pseudo-second-order kinetic model, indicating that chemical adsorption was the rate-limiting step. Sorption isotherms were also determined in single and bi-component solutions with different mass ratio of Cu(II) to Pb(II) (Cu(II)/Pb(II)) and fitted using Langmuir and Freundlich isotherm models. A better fit for Cu(II) and Pb(II) adsorption were obtained with Langmuir model, with a maximum sorption capacity of 168.067 and 228.311mgg(-1) for Cu(II) and Pb(II) in single component solution, 139.860 and 160.256mgg(-1) in bi-component solution (Cu(II)/Pb(II)=1:1), respectively. The present results suggest that TEPA modified chitosan/CoFe2O4 particles are feasible and satisfactory adsorbent for efficient removal of Cu(II) and Pb(II) ions.

  9. Development of polymer-biomolecule core-shell particles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Suthiwangcharoen, Nisaraporn

    Developing efficient strategies to introduce biomolecules around polymeric nanoparticles (NPs) is critical for targeted delivery of therapeutic or diagnostic agents. Although polymeric NPs have been well established, problems such as toxicity, stability, and immunoresistance remain potential concerns. The first part of this dissertation focuses on the development of nanosized targeted drug delivery vehicle in cancer chemotherapy. The vehicle was created by the self-assembly of folate-grafted filamentous bacteriophage M13 with poly(caprolactone- b-2-vinylpyridine) while doxorubicin, the antitumor drugs, was successfully loaded in the interior of the vehicles. These particles offer unique properties of being able to selectively target tumor cells while appearing to be safe and non-toxic to normal cells. Although they have shown great prospects in many biomedical applications, less is known about the interactions between biomolecules and polymers. The next part of the dissertation focuses on the self-assembly of proteins and polymers to create polymer-protein core-shell nanoparticles (PPCS-NPs). Several proteins with different isoelectric points and molecular weights were employed to demonstrate a versatility of our assembly method while a series of esterified derivatives of poly(2-hydroxyethyl methacrylate) (pHEMA) were synthesized to evaluate the interaction between proteins and polymers. Our data indicated that the polymers containing pyridine residues can successfully assemble with proteins, and the mechanism is mainly governed by hydrogen bonding and the hydrophobic/hydrophilic interactions. This in turn helps retaining proteins' folding conformation and functionality, which are also demonstrated in the in vitro/in vivo cellular uptake of the PPCS-NPs in endothelial cells. The last part of the dissertation focuses on the self-assembly of the bienzyme-polymer NPs. Glucose oxidase (GOX) together with horseradish peroxidase (HRP) were employed to construct bienzyme

  10. Critical assessment of the emission spectra of various photosystem II core complexes.

    PubMed

    Chen, Jinhai; Kell, Adam; Acharya, Khem; Kupitz, Christopher; Fromme, Petra; Jankowiak, Ryszard

    2015-06-01

    We evaluate low-temperature (low-T) emission spectra of photosystem II core complexes (PSII-cc) previously reported in the literature, which are compared with emission spectra of PSII-cc obtained in this work from spinach and for dissolved PSII crystals from Thermosynechococcus (T.) elongatus. This new spectral dataset is used to interpret data published on membrane PSII (PSII-m) fragments from spinach and Chlamydomonas reinhardtii, as well as PSII-cc from T. vulcanus and intentionally damaged PSII-cc from spinach. This study offers new insight into the assignment of emission spectra reported on PSII-cc from different organisms. Previously reported spectra are also compared with data obtained at different saturation levels of the lowest energy state(s) of spinach and T. elongatus PSII-cc via hole burning in order to provide more insight into emission from bleached and/or photodamaged complexes. We show that typical low-T emission spectra of PSII-cc (with closed RCs), in addition to the 695 nm fluorescence band assigned to the intact CP47 complex (Reppert et al. J Phys Chem B 114:11884-11898, 2010), can be contributed to by several emission bands, depending on sample quality. Possible contributions include (i) a band near 690-691 nm that is largely reversible upon temperature annealing, proving that the band originates from CP47 with a bleached low-energy state near 693 nm (Neupane et al. J Am Chem Soc 132:4214-4229, 2010; Reppert et al. J Phys Chem B 114:11884-11898, 2010); (ii) CP43 emission at 683.3 nm (not at 685 nm, i.e., the F685 band, as reported in the literature) (Dang et al. J Phys Chem B 112:9921-9933, 2008; Reppert et al. J Phys Chem B 112:9934-9947, 2008); (iii) trap emission from destabilized CP47 complexes near 691 nm (FT1) and 685 nm (FT2) (Neupane et al. J Am Chem Soc 132:4214-4229, 2010); and (iv) emission from the RC pigments near 686-687 nm. We suggest that recently reported emission of single PSII-cc complexes from T. elongatus may not represent

  11. Collapse and fragmentation of magnetic molecular cloud cores with the Enzo AMR MHD code. II. Prolate and oblate cores

    SciTech Connect

    Boss, Alan P.; Keiser, Sandra A.

    2014-10-10

    We present the results of a large suite of three-dimensional models of the collapse of magnetic molecular cloud cores using the adaptive mesh refinement code Enzo2.2 in the ideal magnetohydrodynamics approximation. The cloud cores are initially either prolate or oblate, centrally condensed clouds with masses of 1.73 or 2.73 M {sub ☉}, respectively. The radial density profiles are Gaussian, with central densities 20 times higher than boundary densities. A barotropic equation of state is used to represent the transition from low density isothermal phases, to high density optically thick phases. The initial magnetic field strength ranges from 6.3 to 100 μG, corresponding to clouds that are strongly to marginally supercritical, respectively, in terms of the mass to magnetic flux ratio. The magnetic field is initially uniform and aligned with the clouds' rotation axes, with initial ratios of rotational to gravitational energy ranging from 10{sup –4} to 0.1. Two significantly different outcomes for collapse result: (1) formation of single protostars with spiral arms, and (2) fragmentation into multiple protostar systems. The transition between these two outcomes depends primarily on the initial magnetic field strength, with fragmentation occurring for mass to flux ratios greater than about 14 times the critical ratio for prolate clouds. Oblate clouds typically fragment into several times more clumps than prolate clouds. Multiple, rather than binary, system formation is the general rule in either case, suggesting that binary stars are primarily the result of the orbital dissolution of multiple protostar systems.

  12. Functionality of In vitro Reconstituted Group II Intron RmInt1-Derived Ribonucleoprotein Particles.

    PubMed

    Molina-Sánchez, Maria D; García-Rodríguez, Fernando M; Toro, Nicolás

    2016-01-01

    The functional unit of mobile group II introns is a ribonucleoprotein particle (RNP) consisting of the intron-encoded protein (IEP) and the excised intron RNA. The IEP has reverse transcriptase activity but also promotes RNA splicing, and the RNA-protein complex triggers site-specific DNA insertion by reverse splicing, in a process called retrohoming. In vitro reconstituted ribonucleoprotein complexes from the Lactococcus lactis group II intron Ll.LtrB, which produce a double strand break, have recently been studied as a means of developing group II intron-based gene targeting methods for higher organisms. The Sinorhizobium meliloti group II intron RmInt1 is an efficient mobile retroelement, the dispersal of which appears to be linked to transient single-stranded DNA during replication. The RmInt1IEP lacks the endonuclease domain (En) and cannot cut the bottom strand to generate the 3' end to initiate reverse transcription. We used an Escherichia coli expression system to produce soluble and active RmInt1 IEP and reconstituted RNPs with purified components in vitro. The RNPs generated were functional and reverse-spliced into a single-stranded DNA target. This work constitutes the starting point for the use of group II introns lacking DNA endonuclease domain-derived RNPs for highly specific gene targeting methods.

  13. Functionality of In vitro Reconstituted Group II Intron RmInt1-Derived Ribonucleoprotein Particles

    PubMed Central

    Molina-Sánchez, Maria D.; García-Rodríguez, Fernando M.; Toro, Nicolás

    2016-01-01

    The functional unit of mobile group II introns is a ribonucleoprotein particle (RNP) consisting of the intron-encoded protein (IEP) and the excised intron RNA. The IEP has reverse transcriptase activity but also promotes RNA splicing, and the RNA-protein complex triggers site-specific DNA insertion by reverse splicing, in a process called retrohoming. In vitro reconstituted ribonucleoprotein complexes from the Lactococcus lactis group II intron Ll.LtrB, which produce a double strand break, have recently been studied as a means of developing group II intron-based gene targeting methods for higher organisms. The Sinorhizobium meliloti group II intron RmInt1 is an efficient mobile retroelement, the dispersal of which appears to be linked to transient single-stranded DNA during replication. The RmInt1IEP lacks the endonuclease domain (En) and cannot cut the bottom strand to generate the 3′ end to initiate reverse transcription. We used an Escherichia coli expression system to produce soluble and active RmInt1 IEP and reconstituted RNPs with purified components in vitro. The RNPs generated were functional and reverse-spliced into a single-stranded DNA target. This work constitutes the starting point for the use of group II introns lacking DNA endonuclease domain-derived RNPs for highly specific gene targeting methods. PMID:27730127

  14. North Atlantic Simulations in Coordinated Ocean-Ice Reference Experiments Phase II (CORE-II) . Part II; Inter-Annual to Decadal Variability

    NASA Technical Reports Server (NTRS)

    Danabasoglu, Gokhan; Yeager, Steve G.; Kim, Who M.; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Bleck, Rainer; Boening, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Howard, Armando M.; Kelley, Maxwell

    2015-01-01

    Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958-2007 period from twenty global ocean - sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danabasoglu et al., 2014) which documented the mean states in the North Atlantic from the same models. A major focus of the present study is the representation of Atlantic meridional overturning circulation (AMOC) variability in the participating models. Relationships between AMOC variability and those of some other related variables, such as subpolar mixed layer depths, the North Atlantic Oscillation (NAO), and the Labrador Sea upper-ocean hydrographic properties, are also investigated. In general, AMOC variability shows three distinct stages. During the first stage that lasts until the mid- to late-1970s, AMOC is relatively steady, remaining lower than its long-term (1958-2007) mean. Thereafter, AMOC intensifies with maximum transports achieved in the mid- to late-1990s. This enhancement is then followed by a weakening trend until the end of our integration period. This sequence of low frequency AMOC variability is consistent with previous studies. Regarding strengthening of AMOC between about the mid-1970s and the mid-1990s, our results support a previously identified variability mechanism where AMOC intensification is connected to increased deep water formation in the subpolar North Atlantic, driven by NAO-related surface fluxes. The simulations tend to show general agreement in their representations of, for example, AMOC, sea surface temperature (SST), and subpolar mixed layer depth variabilities. In particular, the observed variability of the North Atlantic SSTs is captured well by all models. These findings indicate that simulated variability and trends are primarily dictated by the atmospheric datasets which include

  15. North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part II: Inter-annual to decadal variability

    NASA Astrophysics Data System (ADS)

    Danabasoglu, Gokhan; Yeager, Steve G.; Kim, Who M.; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Bleck, Rainer; Böning, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Farneti, Riccardo; Fernandez, Elodie; Fogli, Pier Giuseppe; Forget, Gael; Fujii, Yosuke; Griffies, Stephen M.; Gusev, Anatoly; Heimbach, Patrick; Howard, Armando; Ilicak, Mehmet; Jung, Thomas; Karspeck, Alicia R.; Kelley, Maxwell; Large, William G.; Leboissetier, Anthony; Lu, Jianhua; Madec, Gurvan; Marsland, Simon J.; Masina, Simona; Navarra, Antonio; Nurser, A. J. George; Pirani, Anna; Romanou, Anastasia; Salas y Mélia, David; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Sun, Shan; Treguier, Anne-Marie; Tsujino, Hiroyuki; Uotila, Petteri; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Yashayaev, Igor

    2016-01-01

    Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958-2007 period from twenty global ocean - sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danabasoglu et al., 2014) which documented the mean states in the North Atlantic from the same models. A major focus of the present study is the representation of Atlantic meridional overturning circulation (AMOC) variability in the participating models. Relationships between AMOC variability and those of some other related variables, such as subpolar mixed layer depths, the North Atlantic Oscillation (NAO), and the Labrador Sea upper-ocean hydrographic properties, are also investigated. In general, AMOC variability shows three distinct stages. During the first stage that lasts until the mid- to late-1970s, AMOC is relatively steady, remaining lower than its long-term (1958-2007) mean. Thereafter, AMOC intensifies with maximum transports achieved in the mid- to late-1990s. This enhancement is then followed by a weakening trend until the end of our integration period. This sequence of low frequency AMOC variability is consistent with previous studies. Regarding strengthening of AMOC between about the mid-1970s and the mid-1990s, our results support a previously identified variability mechanism where AMOC intensification is connected to increased deep water formation in the subpolar North Atlantic, driven by NAO-related surface fluxes. The simulations tend to show general agreement in their temporal representations of, for example, AMOC, sea surface temperature (SST), and subpolar mixed layer depth variabilities. In particular, the observed variability of the North Atlantic SSTs is captured well by all models. These findings indicate that simulated variability and trends are primarily dictated by the atmospheric datasets which

  16. Three-dimensional combined pyrometric sizing and velocimetry of combusting coal particles. II: Pyrometry.

    PubMed

    Toth, Pal; Draper, Teri; Palotas, Arpad B; Ring, Terry A; Eddings, Eric G

    2015-05-20

    Knowledge of the in situ temperature, size, velocity, and number density of a population of burning coal particles yields insight into the chemical and aerodynamic behavior of a pulverized coal flame (e.g., through means of combustion model validation). Sophisticated and reasonably accurate methods are available for the simultaneous measurement of particle velocity and temperature; however, these methods typically produce single particle measurements in small analyzed volumes and require extensive instrumentation. We present a simple, inexpensive method for the simultaneous, in situ, three-dimensional (3D) measurement of particle velocity, number density, size, and temperature. The proposed method uses a combination of stereo imaging, 3D reconstruction, multicolor pyrometry, and digital image processing techniques. The details of theoretical and algorithmic backgrounds are presented, along with examples and validation experiments. Rigorous uncertainty quantification was performed using numerical simulations to estimate the accuracy of the method and explore how different parameters affect measurement uncertainty. This paper, Part II of two parts that discuss this method [Appl. Opt.54, 4049 (2015)], describes particle temperature and size measurement in overexposed emission images.

  17. Decreased Photosystem II Core Phosphorylation in a Yellow-Green Mutant of Wheat Showing Monophasic Fluorescence Induction Curve.

    PubMed Central

    Giardi, M. T.; Kucera, T.; Briantais, J. M.; Hodges, M.

    1995-01-01

    In the present work we study the regulation of the distribution of the phosphorylated photosystem II (PSII) core populations present in grana regions of the thylakoids from several plant species. The heterogeneous nature of PSII core phosphorylation has previously been reported (M.T. Giardi, F. Rigoni, R. Barbato [1992] Plant Physiol 100: 1948-1954; M.T. Giardi [1993] Planta 190: 107-113). The pattern of four phosphorylated PSII core populations in the grana regions appears to be ubiquitous in higher plants. In the dark, at least two phosphorylated PSII core populations are always detected. A mutant of wheat (Triticum durum) that shows monophasic room-temperature photoreduction of the primary quinone electron acceptor of PSII as measured by chlorophyll fluorescence increase in the presence and absence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea and by fluorescence upon flash illumination in intact leaves also lacks the usual distribution of phosphorylated PSII core populations. In this mutant, the whole PSII core population pattern is changed, probably due to altered threonine kinase activity, which leads to the absence of light-induced phosphorylation of CP43 and D2 proteins. The results, correlated to previous experiments in vivo, support the idea that the functional heterogeneity observed by fluorescence is correlated in part to the PSII protein phosphorylation in the grana. PMID:12228652

  18. Synthesis of tetrahedral quasi-type-II CdSe-CdS core-shell quantum dots.

    PubMed

    Sugunan, Abhilash; Zhao, Yichen; Mitra, Somak; Dong, Lin; Li, Shanghua; Popov, Sergei; Marcinkevicius, Saulius; Toprak, Muhammet S; Muhammed, Mamoun

    2011-10-21

    Synthesis of colloidal nanocrystals of II-VI semiconductor materials has been refined in recent decades and their size dependent optoelectronic properties have been well established. Here we report a facile synthesis of CdSe-CdS core-shell heterostructures using a two-step hot injection process. Red-shifts in absorption and photoluminescence spectra show that the obtained quantum dots have quasi-type-II alignment of energy levels. The obtained nanocrystals have a heterostructure with a large and highly faceted tetrahedral CdS shell grown epitaxially over a spherical CdSe core. The obtained morphology as well as high resolution electron microscopy confirms that the tetrahedral shell have a zinc blende crystal structure. A phenomenological mechanism for the growth and morphology of the nanocrystals is discussed.

  19. Nanoscale indentation of polymer and composite polymer-silica core-shell submicrometer particles by atomic force microscopy.

    PubMed

    Armini, Silvia; Vakarelski, Ivan U; Whelan, Caroline M; Maex, Karen; Higashitani, Ko

    2007-02-13

    Atomic force microscopy was employed to probe the mechanical properties of surface-charged polymethylmethacrylate (PMMA)-based terpolymer and composite terpolymer core-silica shell particles in air and water media. The composite particles were achieved with two different approaches: using a silane coupling agent (composite A) or attractive electrostatic interactions (composite B) between the core and the shell. Young's moduli (E) of 4.3+/-0.7, 11.1+/-1.7, and 8.4+/-1.7 GPa were measured in air for the PMMA-based terpolymer, composite A, and composite B, respectively. In water, E decreases to 1.6+/-0.2 GPa for the terpolymer; it shows a slight decrease to 8.0+/-1.2 GPa for composite A, while it decreases to 2.9+/-0.6 GPa for composite B. This trend is explained by considering a 50% swelling of the polymer in water confirmed by dynamic light scattering. Close agreement is found between the absolute values of elastic moduli determined by nanoindentation and known values for the corresponding bulk materials. The thickness of the silica coating affects the mechanical properties of composite A. In the case of composite B, because the silica shell consists of separate particles free to move in the longitudinal direction that do not individually deform when the entire composite deforms, the elastic properties of the composites are determined exclusively by the properties of the polymer core. These results provide a basis for tailoring the mechanical properties of polymer and composite particles in air and in solution, essential in the design of next-generation abrasive schemes for several technological applications.

  20. Chemical compositions of solid particles present in the Greenland NEEM ice core over the last 110,000 years

    NASA Astrophysics Data System (ADS)

    Oyabu, Ikumi; Iizuka, Yoshinori; Fischer, Hubertus; Schüpbach, Simon; Gfeller, Gideon; Svensson, Anders; Fukui, Manabu; Steffensen, Jørgen Peder; Hansson, Margareta

    2015-09-01

    This study reports the chemical composition of particles present along Greenland's North Greenland Eemian Ice Drilling (NEEM) ice core, back to 110,000 years before present. Insoluble and soluble particles larger than 0.45 µm were extracted from the ice core by ice sublimation, and their chemical composition was analyzed using scanning electron microscope and energy dispersive X-ray spectroscopy and micro-Raman spectroscopy. We show that the dominant insoluble components are silicates, whereas NaCl, Na2SO4, CaSO4, and CaCO3 represent major soluble salts. For the first time, particles of CaMg(CO3)2 and Ca(NO3)2•4H2O are identified in a Greenland ice core. The chemical speciation of salts varies with past climatic conditions. Whereas the fraction of Na salts (NaCl + Na2SO4) exceeds that of Ca salts (CaSO4 + CaCO3) during the Holocene (0.6-11.7 kyr B.P.), the two fractions are similar during the Bølling-Allerød period (12.9-14.6 kyr B.P.). During cold climate such as over the Younger Dryas (12.0-12.6 kyr B.P.) and the Last Glacial Maximum (15.0-26.9 kyr B.P.), the fraction of Ca salts exceeds that of Na salts, showing that the most abundant ion generally controls the salt budget in each period. High-resolution analyses reveal changing particle compositions: those in Holocene ice show seasonal changes, and those in LGM ice show a difference between cloudy bands and clear layers, which again can be largely explained by the availability of ionic components in the atmospheric aerosol body of air masses reaching Greenland.

  1. Microwave-assisted synthesis of water-dispersed CdTe/CdSe core/shell type II quantum dots.

    PubMed

    Sai, Li-Man; Kong, Xiang Yang

    2011-05-27

    A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell) type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported. The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity. The core/shell quantum dots exhibit tunable fluorescence emissions by controlling the thickness of the CdSe shell. The photoluminescent properties were dramatically improved through UV-illuminated treatment, and the time-resolved fluorescence spectra showed that there is a gradual increase of decay lifetime with the thickness of CdSe shell.

  2. Optical and electronic properties of type-II CdSe/CdS core-shell quantum dots

    NASA Astrophysics Data System (ADS)

    Lee, Dea Uk; Yun, Dong Yeol; Kim, Tae Whan; Park, Seoung-Hwan; Choi, Donghyeuk; Kim, Sang Wook; Yoo, Keon-Ho; Lee, Hong Seok; Hae Kwon, Young; Kang, Tae Won

    2015-06-01

    CdSe/CdS core-shell quantum dots (QDs) were synthesized using a facile method in aqueous phase. X-ray diffraction pattern, high-resolution transmission electron microscopy images, and energy dispersive spectroscopy profiles showed that stoichiometric CdSe/CdS QDs were formed. Temperature-dependent photoluminescence spectra showed that the activation energy of CdSe/CdS core-shell QDs was 15 meV. The potential profiles and interband transition energies of the strained type-II CdSe/CdS core-shell QDs were calculated. The calculated interband transition energies slightly decreased from 2.061 to 2.007 eV when the shell thickness increased from 10 to 17 Å. The theoretical interband transition energy of 2.007 eV was in reasonable agreement with the photoluminescence excitonic transition energy of 1.98 eV.

  3. A novel concept of QUADRISO particles. Part II: Utilization for excess reactivity control.

    SciTech Connect

    Talamo, A.

    2010-07-01

    In high temperature reactors, burnable absorbers are utilized to manage the excess reactivity at the early stage of the fuel cycle. In this paper QUADRISO particles are proposed to manage the initial excess reactivity of high temperature reactors. The QUADRISO concept synergistically couples the decrease of the burnable poison with the decrease of the fissile materials at the fuel particle level. This mechanism is set up by introducing a burnable poison layer around the fuel kernel in ordinary TRISO particles or by mixing the burnable poison with any of the TRISO coated layers. At the beginning of life, the initial excess reactivity is small because some neutrons are absorbed in the burnable poison and they are prevented from entering the fuel kernel. At the end of life, when the absorber is almost depleted, more neutrons stream into the fuel kernel of QUADRISO particles causing fission reactions. The mechanism has been applied to a prismatic high temperature reactor with europium or erbium burnable absorbers, showing a significant reduction in the initial excess reactivity of the core.

  4. A novel concept of QUADRISO particles : Part II Utilization for excess reactivity control.

    SciTech Connect

    Talamo, A.

    2011-01-01

    In high temperature reactors, burnable absorbers are utilized to manage the excess reactivity at the early stage of the fuel cycle. In this paper QUADRISO particles are proposed to manage the initial excess reactivity of high temperature reactors. The QUADRISO concept synergistically couples the decrease of the burnable poison with the decrease of the fissile materials at the fuel particle level. This mechanism is set up by introducing a burnable poison layer around the fuel kernel in ordinary TRISO particles or by mixing the burnable poison with any of the TRISO coated layers. At the beginning of life, the initial excess reactivity is small because some neutrons are absorbed in the burnable poison and they are prevented from entering the fuel kernel. At the end of life, when the absorber is almost depleted, more neutrons stream into the fuel kernel of QUADRISO particles causing fission reactions. The mechanism has been applied to a prismatic high temperature reactor with europium or erbium burnable absorbers, showing a significant reduction in the initial excess reactivity of the core.

  5. On Ohmic heating in the Earth's core II: Poloidal magnetic fields obeying Taylor's constraint

    NASA Astrophysics Data System (ADS)

    Jackson, Andrew; Livermore, Philip W.; Ierley, Glenn

    2011-08-01

    The extremely small Ekman and magnetic Rossby numbers in the Earth's core make the magnetostrophic limit an attractive approximation to the core's dynamics. This limit leads to the need for the internal magnetic field to satisfy Taylor's constraint, associated with the vanishing of the azimuthal component of Lorentz torques averaged over every cylinder coaxial with the rotation axis. A special class of three dimensional poloidal interior magnetic fields is chosen that satisfies Taylor's constraint identically on every cylinder in a spherical shell exterior to an inner core. This class of fields, which we call small-circle conservative, demonstrates existence of interior fields satisfying Taylor's constraint, regardless of the morphology of the field on the core surface. These poloidal fields are used to examine the Ohmic dissipation present in the Earth's core. To address the question of dissipation, we demand that the 3-D core fields agree with recent observations of the core field structure on the core-mantle boundary. We use these poloidal fields to show that the true lower bound on core dissipation must necessarily lie below a value that we calculate. For 2004 we find that this lower bound must lie below 10 10 W, and when nutation constraints are also considered the bound must lie below 2 × 10 10 W. These numbers are small compared to suggested values of the order of a few TeraWatts. A more restrictive bound may be forthcoming when the time-dependency of the field is considered, using a variational data assimilation technique.

  6. YOUNG STARLESS CORES EMBEDDED IN THE MAGNETICALLY DOMINATED PIPE NEBULA. II. EXTENDED DATA SET

    SciTech Connect

    Frau, P.; Girart, J. M.; Padovani, M.; Beltran, M. T.; Sanchez-Monge, A.; Busquet, G.; Morata, O.; Masque, J. M.; Estalella, R.; Alves, F. O.; Franco, G. A. P.

    2012-11-01

    The Pipe nebula is a massive, nearby, filamentary dark molecular cloud with a low star formation efficiency threaded by a uniform magnetic field perpendicular to its main axis. It harbors more than a hundred, mostly quiescent, very chemically young starless cores. The cloud is therefore a good laboratory to study the earliest stages of the star formation process. We aim to investigate the primordial conditions and the relation among physical, chemical, and magnetic properties in the evolution of low-mass starless cores. We used the IRAM 30 m telescope to map the 1.2 mm dust continuum emission of five new starless cores, which are in good agreement with previous visual extinction maps. For the sample of nine cores, which includes the four cores studied in a previous work, we derived an A {sub V} to N{sub H{sub 2}} factor of (1.27 {+-} 0.12) Multiplication-Sign 10{sup -21} mag cm{sup 2} and a background visual extinction of {approx}6.7 mag possibly arising from the cloud material. We derived an average core diameter of {approx}0.08 pc, density of {approx}10{sup 5} cm{sup -3}, and mass of {approx}1.7 M {sub Sun }. Several trends seem to exist related to increasing core density: (1) the diameter seems to shrink, (2) the mass seems to increase, and (3) the chemistry tends to be richer. No correlation is found between the direction of the surrounding diffuse medium magnetic field and the projected orientation of the cores, suggesting that large-scale magnetic fields seem to play a secondary role in shaping the cores. We also used the IRAM 30 m telescope to extend the previous molecular survey at 1 and 3 mm of early- and late-time molecules toward the same five new Pipe nebula starless cores, and analyzed the normalized intensities of the detected molecular transitions. We confirmed the chemical differentiation toward the sample and increased the number of molecular transitions of the 'diffuse' (e.g., the 'ubiquitous' CO, C{sub 2}H, and CS), 'oxo-sulfurated' (e.g., SO and

  7. Application of hepatitis B core particles produced by human primary hepatocellular carcinoma (PLC/342) propagated in nude mice to the determination of anti-HBc by passive hemagglutination.

    PubMed

    Miyamoto, K; Itoh, Y; Tsuda, F; Matsui, T; Tanaka, T; Miyamoto, H; Naitoh, S; Imai, M; Usuda, S; Nakamura, T

    1986-05-22

    Human primary hepatocellular carcinoma (PLC/342), carried by nude mice, produces hepatitis B core particles as well as hepatitis B surface antigen particles. Core particles purified form PLC/342 tumors displayed epitopes of hepatitis B core antigen (HBcAg) but not epitopes of hepatitis B e antigen (HBeAg) on their surface, unlike core particles prepared from Dane particles, derived from plasma of asymptomatic carriers, that expressed epitopes of both HBcAg and HBeAg. Core particles obtained from PLC/342 tumors were applied to the determination of antibody to HBcAg (anti-HBc) by passive hemagglutination. The assay detected anti-HBc not only in individuals with persistent infection with hepatitis B virus and in those who had recovered from transient infection, but also in patients with acute type B hepatitis, indicating that it can detect anti-HBc of either IgG or IgM class. A liberal availability of core particles from tumors carried by nude mice, taken together with an easy applicability of the method, would make the passive hemagglutination for anti-HBc a valuable tool in clinical and epidemiological studies, especially in places where sophisticated methods are not feasible.

  8. Correlating Type II and III Radio Bursts with Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Ledbetter, K.; Winter, L. M.; Quinn, R. A.

    2013-12-01

    Solar energetic particles (SEPs) are high-energy particles, such as protons, which are accelerated at the Sun and speed outward into the solar system. If they reach Earth, they can be harmful to satellites, ionospheric communications, and humans in space or on polar airline routes. NOAA defines an SEP event as an occasion when the flux of protons with energies higher than 10 MeV exceeds 10 pfu (particle flux units) as measured by the GOES satellites in geosynchronous orbit. The most intense SEP events are associated with shocks, driven by coronal mass ejections (CMEs), which accelerate particles as they move through the corona. However, very few CMEs result in SEP events. To determine what factors are most important in distinguishing the shock waves that will result in SEP acceleration toward Earth, we take into account several variables and perform a principal component analysis (PCA) to examine their correlations. First, we examine Type II radio bursts, which are caused by electrons accelerating in the same CME-driven shocks that can accelerate SEPs. Using data from the WAVES instrument on the WIND satellite, these Type II radio bursts, as well as the Type III bursts that often accompany them, can be characterized by slope in 1/f space and by intensity. In addition, local Langmuir waves detected by WIND, which are caused by electrons speeding through the plasma surrounding the satellite, can be an indicator of the magnetic connectivity between the active region and Earth. Finally, X-ray flares directly preceding the Type II burst are also taken into consideration in the PCA analysis. The accompanying figure illustrates an example of the WAVES solar radio bursts along with the GOES solar proton flux >= 10 MeV during the SEP event on April 11, 2013. Using PCA to determine which of these factors are most relevant to the onset, intensity, and duration of SEP events will be valuable in future work to predict such events. In total, we present the analysis of all type

  9. Core-shell diode array for high performance particle detectors and imaging sensors: status of the development

    NASA Astrophysics Data System (ADS)

    Jia, G.; Hübner, U.; Dellith, J.; Dellith, A.; Stolz, R.; Plentz, J.; Andrä, G.

    2017-02-01

    We propose a novel high performance radiation detector and imaging sensor by a ground-breaking core-shell diode array design. This novel core-shell diode array are expected to have superior performance respect to ultrahigh radiation hardness, high sensitivity, low power consumption, fast signal response and high spatial resolution simultaneously. These properties are highly desired in fundamental research such as high energy physics (HEP) at CERN, astronomy and future x-ray based protein crystallography at x-ray free electron laser (XFEL) etc.. This kind of detectors will provide solutions for these fundamental research fields currently limited by instrumentations. In this work, we report our progress on the development of core-shell diode array for the applications as high performance imaging sensors and particle detectors. We mainly present our results in the preparation of high aspect ratio regular silicon rods by metal assisted wet chemical etching technique. Nearly 200 μm deep and 2 μm width channels with high aspect ratio have been etched into silicon. This result will open many applications not only for the core-shell diode array, but also for a high density integration of 3D microelectronics devices.

  10. Improving Powder Magnetic Core Properties via Application of Thin, Insulating Silica-Nanosheet Layers on Iron Powder Particles

    PubMed Central

    Ishizaki, Toshitaka; Nakano, Hideyuki; Tajima, Shin; Takahashi, Naoko

    2016-01-01

    A thin, insulating layer with high electrical resistivity is vital to achieving high performance of powder magnetic cores. Using layer-by-layer deposition of silica nanosheets or colloidal silica over insulating layers composed of strontium phosphate and boron oxide, we succeeded in fabricating insulating layers with high electrical resistivity on iron powder particles, which were subsequently used to prepare toroidal cores. The compact density of these cores decreased after coating with colloidal silica due to the substantial increase in the volume, causing the magnetic flux density to deteriorate. Coating with silica nanosheets, on the other hand, resulted in a higher electrical resistivity and a good balance between high magnetic flux density and low iron loss due to the thinner silica layers. Transmission electron microscopy images showed that the thickness of the colloidal silica coating was about 700 nm, while that of the silica nanosheet coating was 30 nm. There was one drawback to using silica nanosheets, namely a deterioration in the core mechanical strength. Nevertheless, the silica nanosheet coating resulted in nanoscale-thick silica layers that are favorable for enhancing the electrical resistivity. PMID:28336835

  11. Oxygen Reduction on Well-Defined Core-Shell Nanocatalysts: Particle Size, Facet, and Pt Shell Thickness Effects

    SciTech Connect

    Wang, J.X.; Inada, H.; Wu, L.; Zhu, Y.; Choi, Y.; Liu, P.; Zhou, W.-P.; Adzic, R.R.

    2009-11-09

    We examined the effects of the thickness of the Pt shell, lattice mismatch, and particle size on specific and mass activities from the changes in effective surface area and activity for oxygen reduction induced by stepwise Pt-monolayer depositions on Pd and Pd{sub 3}Co nanoparticles. The core?shell structure was characterized at the atomic level using Z-contrast scanning transmission electron microscopy coupled with element-sensitive electron energy loss spectroscopy. The enhancements in specific activity are largely attributed to the compressive strain effect based on the density functional theory calculations using a nanoparticle model, revealing the effect of nanosize-induced surface contraction on facet-dependent oxygen binding energy. The results suggest that moderately compressed (111) facets are most conducive to oxygen reduction reaction on small nanoparticles and indicate the importance of concerted structure and component optimization for enhancing core?shell nanocatalysts activity and durability.

  12. Quantitative cellular uptake of double fluorescent core-shelled model submicronic particles

    NASA Astrophysics Data System (ADS)

    Leclerc, Lara; Boudard, Delphine; Pourchez, Jérémie; Forest, Valérie; Marmuse, Laurence; Louis, Cédric; Bin, Valérie; Palle, Sabine; Grosseau, Philippe; Bernache-Assollant, Didier; Cottier, Michèle

    2012-11-01

    The relationship between particles' physicochemical parameters, their uptake by cells and their degree of biological toxicity represent a crucial issue, especially for the development of new technologies such as fabrication of micro- and nanoparticles in the promising field of drug delivery systems. This work was aimed at developing a proof-of-concept for a novel model of double fluorescence submicronic particles that could be spotted inside phagolysosomes. Fluorescein isothiocyanate (FITC) particles were synthesized and then conjugated with a fluorescent pHrodo™ probe, red fluorescence of which increases in acidic conditions such as within lysosomes. After validation in acellular conditions by spectral analysis with confocal microscopy and dynamic light scattering, quantification of phagocytosis was conducted on a macrophage cell line in vitro. The biological impact of pHrodo functionalization (cytotoxicity, inflammatory response, and oxidative stress) was also investigated. Results validate the proof-of-concept of double fluorescent particles (FITC + pHrodo), allowing detection of entirely engulfed pHrodo particles (green and red labeling). Moreover incorporation of pHrodo had no major effects on cytotoxicity compared to particles without pHrodo, making them a powerful tool for micro- and nanotechnologies.

  13. An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations: Hydrography and fluxes

    NASA Astrophysics Data System (ADS)

    Ilicak, Mehmet; Drange, Helge

    2016-04-01

    We compare the simulated Arctic Ocean in fifteen global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II). Most of these models are the ocean and sea-ice components of the coupled climate models used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) experiments. We mainly focus on the hydrography of the Arctic interior, the state of Atlantic Water layer and heat and volume transports at the gateways of the Davis Strait, the Bering Strait, the Fram Strait and the Barents Sea Opening. We found that there is a large spread in temperature in the Arctic Ocean between the models, and generally large differences compared to the observed temperature at intermediate depths. Warm bias models have a strong temperature anomaly of inflow of the Atlantic Water entering the Arctic Ocean through the Fram Strait. Another process that is not represented accurately in the CORE-II models is the formation of cold and dense water, originating on the eastern shelves. In the cold bias models, excessive cold water forms in the Barents Sea and spreads into the Arctic Ocean through the St. Anna Through. There is a large spread in the simulated mean heat and volume transports through the Fram Strait and the Barents Sea Opening. The models agree more on the decadal variability, to a large degree dictated by the common atmospheric forcing. We conclude that the CORE-II model study helps us to understand the crucial biases in the Arctic Ocean. The current coarse resolution state-of-the-art ocean models need to be improved in accurate representation of the Atlantic Water inflow into the Arctic and density currents coming from the shelves.

  14. Hollow-core photonic crystal fiber based multifunctional optical system for trapping, position sensing, and detection of fluorescent particles.

    PubMed

    Shinoj, V K; Murukeshan, V M

    2012-05-15

    We demonstrate a novel multifunctional optical system that is capable of trapping, imaging, position sensing, and fluorescence detection of micrometer-sized fluorescent test particles using hollow-core photonic crystal fiber (HC-PCF). This multifunctional optical system for trapping, position sensing, and fluorescent detection is designed such that a near-IR laser light is used to create an optical trap across a liquid-filled HC-PCF, and a 473 nm laser is employed as a source for fluorescence excitation. This proposed system and the obtained results are expected to significantly enable an efficient integrated trapping platform employing HC-PCF for diagnostic biomedical applications.

  15. Structural variation of solid core and thickness of porous shell of 1.7 μm core-shell silica particles on chromatographic performance: narrow bore columns.

    PubMed

    Omamogho, Jesse O; Hanrahan, John P; Tobin, Joe; Glennon, Jeremy D

    2011-04-15

    Chromatographic and mass transfer kinetic properties of three narrow bore columns (2.1×50 mm) packed with new core-shell 1.7 μm EIROSHELL™-C(18) (EiS-C(18)) particles have been studied. The particles in each column varied in the solid-core to shell particle size ratio (ρ), of 0.59, 0.71 and 0.82, with a porous silica shell thickness of 350, 250 and 150 nm respectively. Scanning and transmission electron microscopy (SEM and TEM), Coulter counter analysis, gas pycnometry, nitrogen sorption analysis and inverse size exclusion chromatography (ISEC) elucidated the physical properties of these materials. The porosity measurement of the packed HILIC and C(18) modified phases provided the means to estimate the phase ratios of the three different shell columns (EiS-150-C(18), EiS-250-C(18) and EiS-350-C(18)). The dependence of the chromatographic performance to the volume fraction of the porous shell was observed for all three columns. The naphtho[2,3-a]pyrene retention factor of k'∼10 on the three EiS-C(18s) employed to obtain the height equivalents to theoretical plates (HETPs) data were achieved by varying the mobile phase compositions and applying the Wilke and Chang relationship to obtain a parallel reduced linear velocity. The Knox fit model gave the coefficient of the reduce HETPs for the three EiS-C(18s). The reduced plate height minimum h(min)=1.9 was achieved for the EiS-150-C(18) column, and generated an efficiency of over 350,000 N/m and h(min)=2.5 equivalent to an efficiency of 200,000 N/m for the EiS-350-C(18) column. The efficiency loss of the EiS-C18 column emanating from the system extra-column volume was discussed with respect to the porous shell thickness.

  16. An atomic model AAA-ATPase/20S core particle sub-complex of the 26S proteasome

    PubMed Central

    Förster, Friedrich; Lasker, Keren; Beck, Florian; Nickell, Stephan; Sali, Andrej; Baumeister, Wolfgang

    2009-01-01

    The 26S proteasome is the most downstream element of the ubiquitin-proteasome pathway of protein degradation. It is composed of the 20S core particle (CP) and the 19S regulatory particle (RP). The RP consists of 6 AAA-ATPases and at least 13 non-ATPase subunits. Based on a cryo-EM map of the 26S proteasome, structures of homologs, and physical protein-protein interactions we derive an atomic model of the AAA-ATPase-CP sub-complex. The ATPase order in our model (Rpt1/Rpt2/Rpt6/Rpt3/Rpt4/Rpt5) is in excellent agreement with the recently identified base-precursor complexes formed during the assembly of the RP. Furthermore, the atomic CP-AAA-ATPase model suggests that the assembly chaperone Nas6 facilitates CP-RP association by enhancing the shape complementarity between Rpt3 and its binding CP alpha subunits partners. PMID:19653995

  17. High-resolution analytical imaging and electron holography of magnetite particles in amyloid cores of Alzheimer’s disease

    NASA Astrophysics Data System (ADS)

    Plascencia-Villa, Germán; Ponce, Arturo; Collingwood, Joanna F.; Arellano-Jiménez, M. Josefina; Zhu, Xiongwei; Rogers, Jack T.; Betancourt, Israel; José-Yacamán, Miguel; Perry, George

    2016-04-01

    Abnormal accumulation of brain metals is a key feature of Alzheimer’s disease (AD). Formation of amyloid-β plaque cores (APC) is related to interactions with biometals, especially Fe, Cu and Zn, but their particular structural associations and roles remain unclear. Using an integrative set of advanced transmission electron microscopy (TEM) techniques, including spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), nano-beam electron diffraction, electron holography and analytical spectroscopy techniques (EDX and EELS), we demonstrate that Fe in APC is present as iron oxide (Fe3O4) magnetite nanoparticles. Here we show that Fe was accumulated primarily as nanostructured particles within APC, whereas Cu and Zn were distributed through the amyloid fibers. Remarkably, these highly organized crystalline magnetite nanostructures directly bound into fibrillar Aβ showed characteristic superparamagnetic responses with saturated magnetization with circular contours, as observed for the first time by off-axis electron holography of nanometer scale particles.

  18. High-resolution analytical imaging and electron holography of magnetite particles in amyloid cores of Alzheimer’s disease

    PubMed Central

    Plascencia-Villa, Germán; Ponce, Arturo; Collingwood, Joanna F.; Arellano-Jiménez, M. Josefina; Zhu, Xiongwei; Rogers, Jack T.; Betancourt, Israel; José-Yacamán, Miguel; Perry, George

    2016-01-01

    Abnormal accumulation of brain metals is a key feature of Alzheimer’s disease (AD). Formation of amyloid-β plaque cores (APC) is related to interactions with biometals, especially Fe, Cu and Zn, but their particular structural associations and roles remain unclear. Using an integrative set of advanced transmission electron microscopy (TEM) techniques, including spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), nano-beam electron diffraction, electron holography and analytical spectroscopy techniques (EDX and EELS), we demonstrate that Fe in APC is present as iron oxide (Fe3O4) magnetite nanoparticles. Here we show that Fe was accumulated primarily as nanostructured particles within APC, whereas Cu and Zn were distributed through the amyloid fibers. Remarkably, these highly organized crystalline magnetite nanostructures directly bound into fibrillar Aβ showed characteristic superparamagnetic responses with saturated magnetization with circular contours, as observed for the first time by off-axis electron holography of nanometer scale particles. PMID:27121137

  19. Core and grain boundary sensitivity of tungsten-oxide sensor devices by molecular beam assisted particle deposition

    NASA Astrophysics Data System (ADS)

    Huelser, T. P.; Lorke, A.; Ifeacho, P.; Wiggers, H.; Schulz, C.

    2007-12-01

    In this study, we investigate the synthesis of WO3 and WOx (2.6≥x≤2.8) by adding different concentrations of tungsten hexafluoride (WF6) into a H2/O2/Ar premixed flame within a low-pressure reactor equipped with a particle-mass spectrometer (PMS). The PMS results show that mean particle diameters dp between 5 and 9 nm of the as-synthesized metal-oxides can be obtained by varying the residence time and precursor concentration in the reactor. This result is further validated by N2 adsorption measurements on the particle surface, which yielded a 91 m2/g surface area, corresponding to a spherical particle diameter of 9 nm (Brunauer-Emmett-Teller technique). H2/O2 ratios of 1.6 and 0.63 are selected to influence the stoichiometry of the powders, resulting in blue-colored WOx and white WO3 respectively. X-ray diffraction (XRD) analysis of the as-synthesized materials indicates that the powders are mostly amorphous, and the observed broad reflexes can be attributed to the orthorhombic structure of β-WO3. Thermal annealing at 973 K for 3 h in air resulted in crystalline WO3 comprised of both monoclinic and orthorhombic phases. The transmission electron microscope micrograph analysis shows that the particles exhibit spherical morphology with some degree of agglomeration. Impedance spectroscopy is used for the electrical characterization of tungsten-oxide thin films with a thickness of 50 nm. Furthermore, the temperature-dependent gas-sensing properties of the material deposited on interdigital capacitors are investigated. Sensitivity experiments reveal two contributions to the overall sensitivity, which result from the surface and the core of each particle.

  20. A new tetranuclear copper(II) Schiff base complex containing Cu 4O 4 cubane core: Structural and spectral characterizations

    NASA Astrophysics Data System (ADS)

    Shit, Shyamapada; Rosair, Georgina; Mitra, Samiran

    2011-04-01

    A new tetra-nuclear coordination complex [Cu 4(HL) 4] ( 1) containing Cu 4O 4 cubane core has been synthesized by using Schiff base ligand [(OH)C 6H 4CH dbnd N sbnd C(CH 3)(CH 2OH) 2] (H 3L), obtained by the 1:1 condensation of 2-amino-2-methyl-1,3-propanediol with salicylaldehyde and thoroughly characterized by micro-analytical, FT-IR, UV-Vis, thermal and room temperature magnetic susceptibility measurements. Structural characterization of the complex has been done by single crystal X-ray diffraction analysis. Structural elucidation reveals versatile coordination modes for two identical alkoxo oxygen atoms of the Schiff base ligand; one in its deprotonated form exhibits μ 3-bridging to bind three similar copper(II) centers whilst the protonated one remains as monodentate or non-coordinating. Structural analysis also shows that the Cu 4O 4 cubane core in 1 consists of four μ 3-alkoxo oxygen bridged copper(II) atoms giving an approximately cubic array of alternating oxygen atoms and copper(II) atoms where the metal centers display both distorted square pyramidal and distorted octahedral geometries.

  1. TRIGGERING COLLAPSE OF THE PRESOLAR DENSE CLOUD CORE AND INJECTING SHORT-LIVED RADIOISOTOPES WITH A SHOCK WAVE. II. VARIED SHOCK WAVE AND CLOUD CORE PARAMETERS

    SciTech Connect

    Boss, Alan P.; Keiser, Sandra A. E-mail: keiser@dtm.ciw.edu

    2013-06-10

    A variety of stellar sources have been proposed for the origin of the short-lived radioisotopes that existed at the time of the formation of the earliest solar system solids, including Type II supernovae (SNe), asymptotic giant branch (AGB) and super-AGB stars, and Wolf-Rayet star winds. Our previous adaptive mesh hydrodynamics models with the FLASH2.5 code have shown which combinations of shock wave parameters are able to simultaneously trigger the gravitational collapse of a target dense cloud core and inject significant amounts of shock wave gas and dust, showing that thin SN shocks may be uniquely suited for the task. However, recent meteoritical studies have weakened the case for a direct SN injection to the presolar cloud, motivating us to re-examine a wider range of shock wave and cloud core parameters, including rotation, in order to better estimate the injection efficiencies for a variety of stellar sources. We find that SN shocks remain as the most promising stellar source, though planetary nebulae resulting from AGB star evolution cannot be conclusively ruled out. Wolf-Rayet (WR) star winds, however, are likely to lead to cloud core shredding, rather than to collapse. Injection efficiencies can be increased when the cloud is rotating about an axis aligned with the direction of the shock wave, by as much as a factor of {approx}10. The amount of gas and dust accreted from the post-shock wind can exceed that injected from the shock wave, with implications for the isotopic abundances expected for a SN source.

  2. Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. II. Varied Shock Wave and Cloud Core Parameters

    NASA Astrophysics Data System (ADS)

    Boss, Alan P.; Keiser, Sandra A.

    2013-06-01

    A variety of stellar sources have been proposed for the origin of the short-lived radioisotopes that existed at the time of the formation of the earliest solar system solids, including Type II supernovae (SNe), asymptotic giant branch (AGB) and super-AGB stars, and Wolf-Rayet star winds. Our previous adaptive mesh hydrodynamics models with the FLASH2.5 code have shown which combinations of shock wave parameters are able to simultaneously trigger the gravitational collapse of a target dense cloud core and inject significant amounts of shock wave gas and dust, showing that thin SN shocks may be uniquely suited for the task. However, recent meteoritical studies have weakened the case for a direct SN injection to the presolar cloud, motivating us to re-examine a wider range of shock wave and cloud core parameters, including rotation, in order to better estimate the injection efficiencies for a variety of stellar sources. We find that SN shocks remain as the most promising stellar source, though planetary nebulae resulting from AGB star evolution cannot be conclusively ruled out. Wolf-Rayet (WR) star winds, however, are likely to lead to cloud core shredding, rather than to collapse. Injection efficiencies can be increased when the cloud is rotating about an axis aligned with the direction of the shock wave, by as much as a factor of ~10. The amount of gas and dust accreted from the post-shock wind can exceed that injected from the shock wave, with implications for the isotopic abundances expected for a SN source.

  3. Particle identification performance of the prototype aerogel RICH counter for the Belle II experiment

    NASA Astrophysics Data System (ADS)

    Iwata, S.; Adachi, I.; Hara, K.; Iijima, T.; Ikeda, H.; Kakuno, H.; Kawai, H.; Kawasaki, T.; Korpar, S.; Križan, P.; Kumita, T.; Nishida, S.; Ogawa, S.; Pestotnik, R.; Šantelj, L.; Seljak, A.; Sumiyoshi, T.; Tabata, M.; Tahirovic, E.; Yusa, Y.

    2016-03-01

    We have developed a new type of particle identification device, called an aerogel ring imaging Cherenkov (ARICH) counter, for the Belle II experiment. It uses silica aerogel tiles as Cherenkov radiators. For detection of Cherenkov photons, hybrid avalanche photo-detectors (HAPDs) are used. The designed HAPD has a high sensitivity to single photons under a strong magnetic field. We have confirmed that the HAPD provides high efficiency for single-photon detection even after exposure to neutron and γ -ray radiation that exceeds the levels expected in the 10-year Belle II operation. In order to confirm the basic performance of the ARICH counter system, we carried out a beam test at the using a prototype of the ARICH counter with six HAPD modules. The results are in agreement with our expectations and confirm the suitability of the ARICH counter for the Belle II experiment. Based on the in-beam performance of the device, we expect that the identification efficiency at 3.5 GeV/c is 97.4% and 4.9% for pions and kaons, respectively. This paper summarizes the development of the HAPD for the ARICH and the evaluation of the performance of the prototype ARICH counter built with the final design components.

  4. Synthesis and electrochemical performance of surface-modified nano-sized core/shell tin particles for lithium ion batteries.

    PubMed

    Schmuelling, Guido; Oehl, Nikolas; Knipper, Martin; Kolny-Olesiak, Joanna; Plaggenborg, Thorsten; Meyer, Hinrich-Wilhelm; Placke, Tobias; Parisi, Jürgen; Winter, Martin

    2014-09-05

    Tin is able to lithiate and delithiate reversibly with a high theoretical specific capacity, which makes it a promising candidate to supersede graphite as the state-of-the-art negative electrode material in lithium ion battery technology. Nevertheless, it still suffers from poor cycling stability and high irreversible capacities. In this contribution, we show the synthesis of three different nano-sized core/shell-type particles with crystalline tin cores and different amorphous surface shells consisting of SnOx and organic polymers. The spherical size and the surface shell can be tailored by adjusting the synthesis temperature and the polymer reagents in the synthesis, respectively. We determine the influence of the surface modifications with respect to the electrochemical performance and characterize the morphology, structure, and thermal properties of the nano-sized tin particles by means of high-resolution transmission electron microscopy, x-ray diffraction, and thermogravimetric analysis. The electrochemical performance is investigated by constant current charge/discharge cycling as well as cyclic voltammetry.

  5. The optical Tamm states at the interface between a photonic crystal and a nanocomposite containing core-shell particles

    NASA Astrophysics Data System (ADS)

    Vetrov, S. Ya; Pankin, P. S.; Timofeev, I. V.

    2016-06-01

    We investigate the optical Tamm states (OTSs) localized at the interface between a photonic crystal (PC) and a nanocomposite consisting of spherical nanoparticles with a dielectric core and a metallic shell, which are dispersed in a transparent matrix, and is characterized by the resonance permittivity. Spectra of transmission, reflection, and absorption of normally incident light waves by the investigated structure are calculated. The spectral manifestation of the Tamm states caused by negative values of the real part of the effective permittivity in the visible spectral range is studied. It is demonstrated that, along with the significantly extended band gap of the PC, the transmission spectrum contains an additional stopband caused by nanocomposite absorption near the resonance frequency. It is shown that the OTSs can be implemented in two band gaps of the PCs, each corresponding to a certain plasmon resonance frequency of the nanocomposite. It is established that the characteristics of the Tamm state localized at the edge of the PCs significantly depend on the ratio between the particle core volume and the total particle volume.

  6. LUC7L3/CROP inhibits replication of hepatitis B virus via suppressing enhancer II/basal core promoter activity

    PubMed Central

    Li, Yuan; Ito, Masahiko; Sun, Suofeng; Chida, Takeshi; Nakashima, Kenji; Suzuki, Tetsuro

    2016-01-01

    The core promoter of hepatitis B virus (HBV) genome is a critical region for transcriptional initiation of 3.5 kb, pregenome and precore RNAs and for the viral replication. Although a number of host-cell factors that potentially regulate the viral promoter activities have been identified, the molecular mechanisms of the viral gene expression, in particular, regulatory mechanisms of the transcriptional repression remain elusive. In this study, we identified LUC7 like 3 pre-mRNA splicing factor (LUC7L3, also known as hLuc7A or CROP) as a novel interacting partner of HBV enhancer II and basal core promoter (ENII/BCP), key elements within the core promoter, through the proteomic screening and found that LUC7L3 functions as a negative regulator of ENII/BCP. Gene silencing of LUC7L3 significantly increased expression of the viral genes and antigens as well as the activities of ENII/BCP and core promoter. In contrast, overexpression of LUC7L3 inhibited their activities and HBV replication. In addition, LUC7L3 possibly contributes to promotion of the splicing of 3.5 kb RNA, which may also be involved in negative regulation of the pregenome RNA level. This is the first to demonstrate the involvement of LUC7L3 in regulation of gene transcription and in viral replication. PMID:27857158

  7. Models of molecular cloud cores. II - Multitransition study of CS-34

    NASA Astrophysics Data System (ADS)

    Mundy, L. G.; Evans, N. J., II; Snell, R. L.; Goldsmith, P. F.; Bally, J.

    1986-07-01

    The dense cores embedded in the M17, S140 and NGC 2024 molecular clouds are mapped in the J = 5-4, J = 3-2, and J = 2-1 transitions of CS-34, and these lines are found to be a factor of 3-4 weaker, and 25 percent narrower, than the CS lines mapped in these cores by Snell et al. (1984). The data are well fitted by spherical LGV models for the excitation, and the excellent correlation between the CS-34 and CS column densities corroborates the absence of a systematic increase in the gas density with decreasing core radius found by Snell et al. Though the CS/CS-34 column density ratio is 9-17, rather than the terrestrial value of 22.5, the column density relationship is linear. The data support of a clump model in which the column density distribution in the core is determined by the volume filling factor of clumps with high, fairly uniform gas density, and it is suggested that the dense gas in the data represents the dominant component of the core gas.

  8. NON-EQUILIBRIUM CHEMISTRY OF DYNAMICALLY EVOLVING PRESTELLAR CORES. II. IONIZATION AND MAGNETIC FIELD

    SciTech Connect

    Tassis, Konstantinos; Willacy, Karen; Yorke, Harold W.; Turner, Neal J.

    2012-07-20

    We study the effect that non-equilibrium chemistry in dynamical models of collapsing molecular cloud cores has on measurements of the magnetic field in these cores, the degree of ionization, and the mean molecular weight of ions. We find that OH and CN, usually used in Zeeman observations of the line-of-sight magnetic field, have an abundance that decreases toward the center of the core much faster than the density increases. As a result, Zeeman observations tend to sample the outer layers of the core and consistently underestimate the core magnetic field. The degree of ionization follows a complicated dependence on the number density at central densities up to 10{sup 5} cm{sup -3} for magnetic models and 10{sup 6} cm{sup -3} in non-magnetic models. At higher central densities, the scaling approaches a power law with a slope of -0.6 and a normalization which depends on the cosmic-ray ionization rate {zeta} and the temperature T as ({zeta}T){sup 1/2}. The mean molecular weight of ions is systematically lower than the usually assumed value of 20-30, and, at high densities, approaches a value of 3 due to the asymptotic dominance of the H{sup +}{sub 3} ion. This significantly lower value implies that ambipolar diffusion operates faster.

  9. Tandem Fusion of Hepatitis B Core Antigen Allows Assembly of Virus-Like Particles in Bacteria and Plants with Enhanced Capacity to Accommodate Foreign Proteins

    PubMed Central

    Peyret, Hadrien; Gehin, Annick; Thuenemann, Eva C.; Blond, Donatienne; El Turabi, Aadil; Beales, Lucy; Clarke, Dean; Gilbert, Robert J. C.; Fry, Elizabeth E.; Stuart, David I.; Holmes, Kris; Stonehouse, Nicola J.; Whelan, Mike; Rosenberg, William; Lomonossoff, George P.; Rowlands, David J.

    2015-01-01

    The core protein of the hepatitis B virus, HBcAg, assembles into highly immunogenic virus-like particles (HBc VLPs) when expressed in a variety of heterologous systems. Specifically, the major insertion region (MIR) on the HBcAg protein allows the insertion of foreign sequences, which are then exposed on the tips of surface spike structures on the outside of the assembled particle. Here, we present a novel strategy which aids the display of whole proteins on the surface of HBc particles. This strategy, named tandem core, is based on the production of the HBcAg dimer as a single polypeptide chain by tandem fusion of two HBcAg open reading frames. This allows the insertion of large heterologous sequences in only one of the two MIRs in each spike, without compromising VLP formation. We present the use of tandem core technology in both plant and bacterial expression systems. The results show that tandem core particles can be produced with unmodified MIRs, or with one MIR in each tandem dimer modified to contain the entire sequence of GFP or of a camelid nanobody. Both inserted proteins are correctly folded and the nanobody fused to the surface of the tandem core particle (which we name tandibody) retains the ability to bind to its cognate antigen. This technology paves the way for the display of natively folded proteins on the surface of HBc particles either through direct fusion or through non-covalent attachment via a nanobody. PMID:25830365

  10. Influence of addition of larger particles into 3-nm particles of TiO II film on the performance of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Hongxia; Bell, John

    2007-12-01

    The performance of dye-sensitized solar cells (DSC) based on the TiO II film composed of 3 nm particles and mixtures of 3 nm and 400 nm or 25 nm particles synthesized by spray pyrolysis deposition has been investigated. An energy conversion efficiency of 8.44% (under the illumination of 100 mW/cm2, AM 1.5) has been achieved with the DSC based on the nanocrystalline TiO II film consisting of 3 nm and 25 nm particles with a ratio of 3:4 by weight. The maximum incident photo-to-current conversion efficiency (IPCE) of the cell is 0.91, which is much higher than the maximum IPCE of the photoelectrode composed of either only 3 nm or the mixture of 3 nm and 400 nm particles (with the same ratio by weight) over the visible spectrum. SEM images show the formation of clusters in the TiO II film containing 25 nm particles. It is proposed that the clusters are responsible for the high IPCE by increasing the light harvesting efficiency through enhanced light scattering and facilitating the electron transport of the DSC.

  11. Preparation of nanosized drug particles by the coating of inorganic cores: naproxen and ketoprofen on alumina.

    PubMed

    Joguet, Laurent; Sondi, Ivan; Matijević, Egon

    2002-07-15

    Nanosized alumina particles with modal diameters of 8 and 13 nm, respectively, were successfully coated by the adsorption of naproxen [(+)-6-methoxy-alpha-methyl-2-naphthalene acetic acid] and ketoprofen [alpha-methyl-3-(4-methylbenzoil) benzene acetic acid] in aqueous and ethanol solutions. The presence of the drugs at the alumina surface was confirmed by attenuated total reflection infrared spectroscopy and electrokinetic measurements, while their bound amounts were assessed by thermogravimetric analysis.

  12. I. Statistical mechanics of bubbly liquids. II. Behavior of sheared suspensions of non-Brownian particles

    NASA Astrophysics Data System (ADS)

    Yurkovetsky, Yevgeny

    I. The dynamics of bubbles at high Reynolds numbers is studied from the viewpoint of statistical mechanics. Individual bubbles are treated as dipoles in potential flow. A virtual mass matrix of the system of bubbles is introduced, which depends on the instantaneous positions of the bubbles, and is used to calculate the energy of the bubbly flow as a quadratic form of the bubbles' velocities. The energy is shown to be the system's Hamiltonian and is used to construct a canonical ensemble partition function, which explicitly includes the total impulse of the suspension along with its energy. The Hamiltonian is decomposed into an effective potential due to the bubbles' collective motion and a kinetic term due to the random motion about the mean. An effective bubble temperature-a measure of the relative importance of the bubbles' relative to collective motion-is derived with the help of the impulse-dependent partition function. Two effective potentials are shown to operate: one, due to the mean motion of the bubbles, dominates at low bubble temperatures where it leads to their grouping in flat clusters normal to the direction of the collective motion, while the other, temperature invariant, is due to the bubbles' position-dependent virtual mass and results in their mutual repulsion. Numerical evidence is presented for the existence of the effective potentials, the condensed and dispersed phases and a phase transition. II. Suspensions of non-Brownian particles in simple shear flow of a Newtonian solvent in the range of particle phase concentration, φ, from 0.05 to 0.52, are studied numerically by Stokesian Dynamics. The simulations are a function of φ and the dimensionless shear rate, γ*, which measures the relative importance of the shear and short-ranged interparticle forces. The pair-distribution functions, shear viscosity, normal stress differences, suspension pressure, long-time self-diffusion coefficients, and mean square of the particle velocity fluctuations

  13. Nanoscale Au-In alloy-oxide core-shell particles as electrocatalysts for efficient hydroquinone detection

    DOE PAGES

    Sutter, E.; Tong, X.; Medina-Plaza, C.; ...

    2015-10-09

    The presence of hydroquinone (HQ), a phenol ubiquitous in nature and widely used in industry, needs to be monitored because of its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast, and noninvasive electrochemical measurements on indium tin oxide (ITO) electrodes modified with nanoparticles comprising bimetallic Au–In cores and mixed Au–In oxide shells. Whereas bare ITO electrodes show very low activity for the detection of HQ, their modification with Au–In core–shell nanoparticles induces a pronounced shift of the oxidation peak to lower potentials, i.e., facilitated oxidation. The response of the different electrodes was correlated withmore » the initial composition of the bimetallic nanoparticle cores, which in turn determined the amount of Au and In stabilized on the surface of the amorphous Au–In oxide shells available for the electrochemical reaction. While adding core–shell nanostructures with different compositions of the alloy core facilitates the electrocatalytic (reduction-) oxidation of HQ, the activity is highest for particles with AuIn cores (i.e., a Au:In ratio of 1). This optimal system is found to follow a single pathway, the two-electron oxidation of the quinone–hydroquinone couple, which gives rise to high oxidation peaks and is most effective in facilitating the electrode-to-analyte charge transfer and thus detection. The limits of detection (LOD) decreased when increasing the amount of Au exposed on the surface of the amorphous Au–In oxide shells. As a result the LODs were in the range of 10–5 – 10–6 M and were lower than those obtained using bulk Au.« less

  14. Nanoscale Au-In alloy-oxide core-shell particles as electrocatalysts for efficient hydroquinone detection

    SciTech Connect

    Sutter, E.; Tong, X.; Medina-Plaza, C.; Rodriguez-Mendez, M. L.; Sutter, P.

    2015-10-09

    The presence of hydroquinone (HQ), a phenol ubiquitous in nature and widely used in industry, needs to be monitored because of its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast, and noninvasive electrochemical measurements on indium tin oxide (ITO) electrodes modified with nanoparticles comprising bimetallic Au–In cores and mixed Au–In oxide shells. Whereas bare ITO electrodes show very low activity for the detection of HQ, their modification with Au–In core–shell nanoparticles induces a pronounced shift of the oxidation peak to lower potentials, i.e., facilitated oxidation. The response of the different electrodes was correlated with the initial composition of the bimetallic nanoparticle cores, which in turn determined the amount of Au and In stabilized on the surface of the amorphous Au–In oxide shells available for the electrochemical reaction. While adding core–shell nanostructures with different compositions of the alloy core facilitates the electrocatalytic (reduction-) oxidation of HQ, the activity is highest for particles with AuIn cores (i.e., a Au:In ratio of 1). This optimal system is found to follow a single pathway, the two-electron oxidation of the quinone–hydroquinone couple, which gives rise to high oxidation peaks and is most effective in facilitating the electrode-to-analyte charge transfer and thus detection. The limits of detection (LOD) decreased when increasing the amount of Au exposed on the surface of the amorphous Au–In oxide shells. As a result the LODs were in the range of 10–5 – 10–6 M and were lower than those obtained using bulk Au.

  15. Novel co-axial prilling technique for the development of core-shell particles as delayed drug delivery systems.

    PubMed

    Del Gaudio, Pasquale; Auriemma, Giulia; Russo, Paola; Mencherini, Teresa; Campiglia, Pietro; Stigliani, Mariateresa; Aquino, Rita Patrizia

    2014-08-01

    In this study, biocompatible double layered beads consisting of pectin core and alginate shell were prepared through a single step manufacturing process based on prilling apparatus equipped with co-axial nozzles. The core was loaded with piroxicam (PRX) as model non-steroidal anti-inflammatory drug (NSAID). Morphology, size distribution and shape of the double layered beads varied depending on the operative conditions and polymer concentrations. Co-axial nozzles size, applied vibration frequency, gelling conditions and, mainly, polymers mass ratio were identified as critical variables. Particularly, the relative viscosity of polymeric feed solutions inside the nozzle was the key parameter to obtain homogeneous and well-formed coated particles. The produced beads were investigated for the release kinetic in different media. Once PRX was encapsulated within the pectin core, a controlled release pattern was observed. Particularly, beads produced with 4:1 core/shell ratio (F4) released less than 30% of PRX in simulated gastric fluid (SGF) while total liberation of the drug was achieved during the next 3h in simulated intestinal fluid (SIF). More interesting, F4 tested in SIF was able to release drug in a delayed and sustained manner at established time points (2h_8.2%, 3h_32.2%, 4h_70.1% and 5h_about 100%). Based on the above results, co-axial prilling approach is expected to provide success in manufacturing systems with delayed drug release profiles. Such systems may be potentially useful in targeting diseases which are affected by the circadian rhythm, such as chronic inflammation.

  16. Isocratic and gradient impedance plot analysis and comparison of some recently introduced large size core-shell and fully porous particles.

    PubMed

    Vanderheyden, Yoachim; Cabooter, Deirdre; Desmet, Gert; Broeckhoven, Ken

    2013-10-18

    The intrinsic kinetic performance of three recently commercialized large size (≥4μm) core-shell particles packed in columns with different lengths has been measured and compared with that of standard fully porous particles of similar and smaller size (5 and 3.5μm, respectively). The kinetic performance is compared in both absolute (plot of t0 versus the plate count N or the peak capacity np for isocratic and gradient elution, respectively) and dimensionless units. The latter is realized by switching to so-called impedance plots, a format which has been previously introduced (as a plot of t0/N(2) or E0 versus Nopt/N) and has in the present study been extended from isocratic to gradient elution (where the impedance plot corresponds to a plot of t0/np(4) versus np,opt(2)/np(2)). Both the isocratic and gradient impedance plot yielded a very similar picture: the clustered impedance plot curves divide into two distinct groups, one for the core-shell particles (lowest values, i.e. best performance) and one for the fully porous particles (highest values), confirming the clear intrinsic kinetic advantage of core-shell particles. If used around their optimal flow rate, the core-shell particles displayed a minimal separation impedance that is about 40% lower than the fully porous particles. Even larger gains in separation speed can be achieved in the C-term regime.

  17. Active galactic nuclei. II - The acceleration of relativistic particles in a cluster of accreting black holes

    NASA Technical Reports Server (NTRS)

    Pacholczyk, A. G.; Stepinski, T. F.

    1988-01-01

    An accreting cluster of black holes in an active galactic nucleus is a natural site for a system of shock structures with a hierarchy of sizes, corresponding to the distribution of masses in the cluster. Accreted gas containing some magnetic fields and supersonically falling onto the core forms shocks on the outside of each hole and these shocks are capable of accelerating relativistic particles. The energies reached in a single shock are size rather than acceleration time limited and are proportional to the mass of the hole with a proportionality constant being a function of the position of the hole within a cluster and the model of the cluster and the shock formation. These energies are adequate to explain the observed properties of synchrotron and inverse-Compton radiation from these objects. The resulting energy spectrum of particles in the cluster in 'zeroth' approximation has the form of a doubly broken power law with indices of two and three on both extremes of the energy domain respectively, bridged by an index of about 2.5.

  18. Recognition of core and flanking amino acids of MHC class II-bound peptides by the T cell receptor.

    PubMed

    Sant'Angelo, Derek B; Robinson, Eve; Janeway, Charles A; Denzin, Lisa K

    2002-09-01

    CD4 T cells recognize peptides bound to major histocompatibility complex (MHC) class II molecules. Most MHC class II molecules have four binding pockets occupied by amino acids 1, 4, 6, and 9 of the minimal peptide epitope, while the residues at positions 2, 3, 5, 7, and 8 are available to interact with the T cell receptor (TCR). In addition MHC class II bound peptides have flanking residues situated outside of this peptide core. Here we demonstrate that the flanking residues of the conalbumin peptide bound to I-A(k) have no effect on recognition by the D10 TCR. To study the role of peptide flanks for recognition by a second TCR, we determined the MHC and TCR contacting amino acids of the I-A(b) bound Ealpha peptide. The Ealpha peptide is shown to bind I-A(b) using four alanines as anchor residues. TCR recognition of Ealpha peptides with altered flanking residues again suggested that, in general, no specific interactions occurred with the peptide flanks. However, using an HLA-DM-mediated technique to measure peptide binding to MHC class II molecules, we found that the peptide flanking residues contribute substantially to MHC binding.

  19. Characterization of exposures to nanoscale particles and fibers during solid core drilling of hybrid carbon nanotube advanced composites.

    PubMed

    Bello, Dhimiter; Wardle, Brian L; Zhang, Jie; Yamamoto, Namiko; Santeufemio, Christopher; Hallock, Marilyn; Virji, M Abbas

    2010-01-01

    This work investigated exposures to nanoparticles and nanofibers during solid core drilling of two types of advanced carbon nanotube (CNT)-hybrid composites: (1) reinforced plastic hybrid laminates (alumina fibers and CNT); and (2) graphite-epoxy composites (carbon fibers and CNT). Multiple real-time instruments were used to characterize the size distribution (5.6 nm to 20 microm), number and mass concentration, particle-bound polyaromatic hydrocarbons (b-PAHs), and surface area of airborne particles at the source and breathing zone. Time-integrated samples included grids for electron microscopy characterization of particle morphology and size resolved (2 nm to 20 microm) samples for the quantification of metals. Several new important findings herein include generation of airborne clusters of CNTs not seen during saw-cutting of similar composites, fewer nanofibers and respirable fibers released, similarly high exposures to nanoparticles with less dependence on the composite thickness, and ultrafine (< 5 nm) aerosol originating from thermal degradation of the composite material.

  20. Preparation of bovine serum albumin surface-imprinted submicrometer particles with magnetic susceptibility through core-shell miniemulsion polymerization.

    PubMed

    Tan, Chau Jin; Chua, Hong Gap; Ker, Kwee Hong; Tong, Yen Wah

    2008-02-01

    Molecular imprinting is a state-of-the-art technique for preparing mimics of natural, biological receptors. Nevertheless, the imprinting of macromolecules like proteins remains a challenge due to their bulkiness and sensitivity to denaturation. In this work, a surface imprinting strategy based on covalently immobilized template molecules was adopted for protein imprinting. Bovine serum albumin (BSA) surface-imprinted submicrometer particles (500-600 nm) with magnetic susceptibility were prepared through a two-stage core-shell miniemulsion polymerization system using methyl methacrylate and ethylene glycol dimethacrylate as functional and cross-linking monomers, respectively. The particles possessed a novel red blood cell-like structure and exhibited a very favorable recognition property toward the template BSA molecules in aqueous medium. In a two-protein system, the particles had shown a very high specific recognition of the template proteins over the nontemplate proteins. The magnetic susceptibility was imparted through the successful encapsulation of Fe3O4 nanoparticles. Their superparamagnetic nature increases their potential applications in the fields such as magnetic bioseparation, cell labeling, and bioimaging. In addition, the importance of template immobilization for successful protein imprinting had also been illustrated to demonstrate the potential of this approach as a general methodology for protein imprinting.

  1. 3.9 Å structure of the nucleosome core particle determined by phase-plate cryo-EM

    PubMed Central

    Chua, Eugene Y.D.; Vogirala, Vinod K.; Inian, Oviya; Wong, Andrew S.W.; Nordenskiöld, Lars; Plitzko, Juergen M.; Danev, Radostin; Sandin, Sara

    2016-01-01

    The Volta phase plate is a recently developed electron cryo-microscopy (cryo-EM) device that enables contrast enhancement of biological samples. Here we have evaluated the potential of combining phase-plate imaging and single particle analysis to determine the structure of a small protein–DNA complex. To test the method, we made use of a 200 kDa Nucleosome Core Particle (NCP) reconstituted with 601 DNA for which a high-resolution X-ray crystal structure is known. We find that the phase plate provides a significant contrast enhancement that permits individual NCPs and DNA to be clearly identified in amorphous ice. The refined structure from 26,060 particles has an overall resolution of 3.9 Å and the density map exhibits structural features consistent with the estimated resolution, including clear density for amino acid side chains and DNA features such as the phosphate backbone. Our results demonstrate that phase-plate cryo-EM promises to become an important method to determine novel near-atomic resolution structures of small and challenging samples, such as nucleosomes in complex with nucleosome-binding factors. PMID:27563056

  2. Integration of Skills and Competencies in the Missouri Marketing Education Core Curriculum. Section II.

    ERIC Educational Resources Information Center

    Ruhland, Sheila K.; Wilkinson, Richard F.

    This publication contains teaching activities for the Fundamentals of Marketing and Advanced Marketing curriculum. Chapter 1 presents an alignment of the marketing education core competencies within the nine curriculum units for Fundamentals of Marketing and Advanced Marketing as they relate to the basic academic skills, advanced academic skills,…

  3. Core II Materials for Rural Agricultural Programs. Units A-D.

    ERIC Educational Resources Information Center

    Biondo, Ron; And Others

    This curriculum guide includes teaching packets for 21 problem areas to be included in a core curriculum for 10th-grade students enrolled in a rural agricultural program. Covered in the four units included in this volume are orientation to agricultural occupations (orientation to vocational agricultural course and developing effective study…

  4. Core II Materials for Rural Agriculture Programs. Units E-H.

    ERIC Educational Resources Information Center

    Biondo, Ron; And Others

    This curriculum guide includes teaching packets for 21 problem areas to be included in a core curriculum for 10th grade students enrolled in a rural agricultural program. Covered in the four units included in this volume are crop science (harvesting farm crops and growing small grains); soil science and conservation of natural resources…

  5. Radiation Hard Silicon Particle Detectors for Phase-II LHC Trackers

    NASA Astrophysics Data System (ADS)

    Oblakowska-Mucha, A.

    2017-02-01

    The major LHC upgrade is planned after ten years of accelerator operation. It is foreseen to significantly increase the luminosity of the current machine up to 1035 cm‑2s‑1 and operate as the upcoming High Luminosity LHC (HL-LHC) . The major detectors upgrade, called the Phase-II Upgrade, is also planned, a main reason being the aging processes caused by severe particle radiation. Within the RD50 Collaboration, a large Research and Development program has been underway to develop silicon sensors with sufficient radiation tolerance for HL-LHC trackers. In this summary, several results obtained during the testing of the devices after irradiation to HL-LHC levels are presented. Among the studied structures, one can find advanced sensors types like 3D silicon detectors, High-Voltage CMOS technologies, or sensors with intrinsic gain (LGAD). Based on these results, the RD50 Collaboration gives recommendation for the silicon detectors to be used in the detector upgrade.

  6. Search for heavy long-lived particles that decay to photons at CDF II.

    PubMed

    Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Almenar, C Cuenca; Cuevas, J; Culbertson, R; Cully, J C; Daronco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dörr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; da Costa, J Guimaraes; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, E; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuno, S; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vazquez, F; Velev, G; Veramendi, G; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

    2007-09-21

    We present the first search for heavy, long-lived particles that decay to photons at a hadron collider. We use a sample of gamma + jet + missing transverse energy events in pp[over] collisions at square root[s] = 1.96 TeV taken with the CDF II detector. Candidate events are selected based on the arrival time of the photon at the detector. Using an integrated luminosity of 570 pb(-1) of collision data, we observe 2 events, consistent with the background estimate of 1.3+/-0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits in a supersymmetric model with [Formula: see text] and place the world-best 95% C.L. lower limit on the [Formula: see text] mass of 101 GeV/c(2) at [Formula: see text].

  7. Highly efficient near-infrared light-emitting diodes by using type-II CdTe/CdSe core/shell quantum dots as a phosphor.

    PubMed

    Shen, Huaibin; Zheng, Ying; Wang, Hongzhe; Xu, Weiwei; Qian, Lei; Yang, Yixing; Titov, Alexandre; Hyvonen, Jake; Li, Lin Song

    2013-11-29

    In this paper, we present an innovative method for the synthesis of CdTe/CdSe type-II core/shell structure quantum dots (QDs) using 'greener' chemicals. The PL of CdTe/CdSe type-II core/shell structure QDs ranges from 600 to 820 nm, and the as-synthesized core/shell structures show narrow size distributions and stable and high quantum yields (50–75%). Highly efficient near-infrared light-emitting diodes (LEDs) have been demonstrated by employing the CdTe/CdSe type-II core/shell QDs as emitters. The devices fabricated based on these type-II core/shell QDs show color-saturated near-infrared emission from the QD layers, a low turn-on voltage of 1.55 V, an external quantum efficiency (EQE) of 1.59%, and a current density and maximum radiant emittance of 2.1 × 10(3) mA cm−2 and 17.7 mW cm−2 at 8 V; it is the first report to use type-II core/shell QDs as near-infrared emitters and these results may offer a practicable platform for the realization of near-infrared QD-based light-emitting diodes, night-vision-readable displays, and friend/foe identification system.

  8. Synthesis of Nanostructured/Macroscopic Low-Density Copper Foams Based on Metal-Coated Polymer Core-Shell Particles.

    PubMed

    Kim, Sung Ho; Bazin, Nick; Shaw, Jessica I; Yoo, Jae-Hyuck; Worsley, Marcus A; Satcher, Joe H; Sain, John D; Kuntz, Joshua D; Kucheyev, Sergei O; Baumann, Theodore F; Hamza, Alex V

    2016-12-21

    A robust, millimeter-sized low-density Cu foam with ∼90% (v/v) porosity, ∼30 nm thick walls, and ∼1 μm diameter spherical pores is prepared by the slip-casting of metal-coated polymer core-shell particles followed by a thermal removal of the polymer. In this paper, we report our key findings that enable the development of the low-density Cu foams. First, we need to synthesize polystyrene (PS) particles coated with a very thin Cu layer (in the range of tens of nanometers). A simple reduction in the amount of Cu deposited onto the PS was not sufficient to form such a low-density Cu foams due to issues related to foam collapse and densification upon the subsequent polymer removal step. Precise control over the morphology of the Cu coating on the particles is essential for the synthesis of a lower density of foams. Second, improving the dispersion of PS-Cu particles in a suspension used for the casting as well as careful optimization of a baking condition minimize the formation of irregular large voids, leading to Cu foams with a more uniform packing and a better connectivity of neighboring Cu hollow shells. Finally, we analyzed mechanical properties of the Cu foams with a depth-sensing indentation test. The uniform Cu foams show a significant improvement in mechanical properties (∼1.5× modulus and ∼3× hardness) compared to those of uncontrolled foam samples with a similar foam density but irregular large voids. Higher surface areas and a good electric conductivity of the Cu foams present a great potential to future applications.

  9. Refactoring the Six-Gene Photosystem II Core in the Chloroplast of the Green Algae Chlamydomonas reinhardtii.

    PubMed

    Gimpel, Javier A; Nour-Eldin, Hussam H; Scranton, Melissa A; Li, Daphne; Mayfield, Stephen P

    2016-07-15

    Oxygenic photosynthesis provides the energy to produce all food and most of the fuel on this planet. Photosystem II (PSII) is an essential and rate-limiting component of this process. Understanding and modifying PSII function could provide an opportunity for optimizing photosynthetic biomass production, particularly under specific environmental conditions. PSII is a complex multisubunit enzyme with strong interdependence among its components. In this work, we have deleted the six core genes of PSII in the eukaryotic alga Chlamydomonas reinhardtii and refactored them in a single DNA construct. Complementation of the knockout strain with the core PSII synthetic module from three different green algae resulted in reconstitution of photosynthetic activity to 85, 55, and 53% of that of the wild-type, demonstrating that the PSII core can be exchanged between algae species and retain function. The strains, synthetic cassettes, and refactoring strategy developed for this study demonstrate the potential of synthetic biology approaches for tailoring oxygenic photosynthesis and provide a powerful tool for unraveling PSII structure-function relationships.

  10. I. Fission probabilities, fission barriers, and shell effects. II. Particle structure functions

    NASA Astrophysics Data System (ADS)

    Jing, Kexing

    1999-11-01

    In Part I, fission excitation functions of osmium isotopes 185,186,187,189 Os produced in 3He + 182,183,184,186W reactions, and of polonium isotopes 209,210,211,212Po produced in 3He/4He + 206,207,208Pb reactions, were measured with high precision. These excitation functions have been analyzed in detail based upon the transition state formalism. The fission barriers, and shell effects for the corresponding nuclei are extracted from the detailed analyses. A novel approach has been developed to determine upper limits of the transient time of the fission process. The upper limits are constrained by the fission probabilities of neighboring isotopes. The upper limits for the transient time set with this new method are 15 × 10-21 sec and 25 × 10-21 sec for Os and Po compound nuclei, respectively. In Part II, we report on a search for evidence of the optical modulations in the energy spectra of alpha particles emitted from hot compound nuclei. The optical modulations are expected to arise from the α- particle interaction with the rest of the nucleus as the particle prepares to exit. Some evidence for the modulations has been observed in the alpha spectra measured in the 3He-induced reactions, 3He + natAg in particular. The identification of the modulations involves a technique that substracts the bulk statistical background from the measured alpha spectra, in order for the modulations to become visible in the residuals. Due to insufficient knowledge of the background spectra, however, the presented evidence should only be regarded as preliminary and tentative.

  11. I. Fission Probabilities, Fission Barriers, and Shell Effects. II. Particle Structure Functions

    SciTech Connect

    Jing, Kexing

    1999-05-01

    In Part I, fission excitation functions of osmium isotopes 185,186, 187, 189 Os produced in 3He +182,183, 184, 186W reactions, and of polonium isotopes 209,210, 211, 212Po produced in 3He/4He + 206, 207, 208Pb reactions, were measured with high precision. These excitation functions have been analyzed in detail based upon the transition state formalism. The fission barriers, and shell effects for the corresponding nuclei are extracted from the detailed analyses. A novel approach has been developed to determine upper limits of the transient time of the fission process. The upper limits are constrained by the fission probabilities of neighboring isotopes. The upper limits for the transient time set with this new method are 15x 10–21 sec and 25x 10–21 sec for 0s and Po compound nuclei, respectively. In Part II, we report on a search for evidence of the optical modulations in the energy spectra of alpha particles emitted from hot compound nuclei. The optical modulations are expected to arise from the ~-particle interaction with the rest of the nucleus as the particle prepares to exit. Some evidence for the modulations has been observed in the alpha spectra measured in the 3He-induced reactions, 3He + natAg in particular. The identification of the modulations involves a technique that subtracts the bulk statistical background from the measured alpha spectra, in order for the modulations to become visible in the residuals. Due to insufficient knowledge of the background spectra, however, the presented evidence should only be regarded as preliminary and tentative.

  12. Flow and particle dispersion in a pulmonary alveolus--part II: effect of gravity on particle transport.

    PubMed

    Chhabra, Sudhaker; Prasad, Ajay K

    2010-05-01

    The acinar region of the human lung comprises about 300x10(6) alveoli, which are responsible for gas exchange between the lung and the blood. As discussed in Part I (Chhabra and Prasad, "Flow and Particle Dispersion in a Pulmonary Alveolus-Part I: Velocity Measurements and Convective Particle Transport," ASME J. Biomech. Eng., 132, p. 051009), the deposition of aerosols in the acinar region can either be detrimental to gas exchange (as in the case of harmful particulate matter) or beneficial (as in the case of inhalable pharmaceuticals). We measured the flow field inside an in-vitro model of a single alveolus mounted on a bronchiole and calculated the transport and deposition of massless particles in Part I. This paper focuses on the transport and deposition of finite-sized particles ranging from 0.25 microm to 4 microm under the combined influence of flow-induced advection (computed from velocity maps obtained by particle image velocimetry) and gravitational settling. Particles were introduced during the first inhalation cycle and their trajectories and deposition statistics were calculated for subsequent cycles for three different particle sizes (0.25 microm, 1 microm, and 4 microm) and three alveolar orientations. The key outcome of the study is that particles particles (d(p)=1 microm) deviate to some extent from streamlines and exhibit complex trajectories. The motion of large particles >or=4 microm is dominated by gravitational settling and shows little effect of fluid advection. Additionally, small and midsize particles deposit at about two-thirds height in the alveolus irrespective of the gravitational orientation whereas the deposition of large particles is governed primarily by the orientation of the gravity vector.

  13. Self-assembly of gold nanoparticles and polystyrene: a highly versatile approach to the preparation of colloidal particles with polystyrene cores and gold nanoparticle coronae.

    PubMed

    Tian, Jia; Jin, Jie; Zheng, Fan; Zhao, Hanying

    2010-06-01

    Colloidal particles with polystyrene (PS) cores and gold nanoparticle (AuNP) coronae were prepared on the basis of the self-assembly of AuNP's and PS. Citrate-stabilized AuNP's were dispersed in aqueous solution, and PS with thiol terminal groups (PS-SH) was dissolved in toluene. A stable emulsion was obtained by mixing the two solutions. Optical microscope images indicate that after grafting of PS-SH to the citrate-stabilized AuNP's at liquid-liquid interface, the interfacial tension is reduced and the average size of toluene droplets in the emulsion decreases. Transmission electron microscope (TEM) results also prove the grafting of PS-SH to AuNP's and the location of the hybrid nanoparticles at the liquid-liquid interface. Colloidal particles with PS cores and AuNP coronae were prepared by adding the emulsion to excess methanol. The weight ratio of PS-SH to AuNP exerts a significant effect on the size of colloidal particles. TEM and dynamic light scattering results both indicate that the size of colloidal particles increases with the weight ratio. The application of the core-shell-structured colloidal particles to protein separation was also investigated in this research. Colloidal particles with PS-coated magnetic nanoparticles in the cores were also prepared by this strategy.

  14. Enhanced group II intron retrohoming in magnesium-deficient Escherichia coli via selection of mutations in the ribozyme core

    PubMed Central

    Truong, David M.; Sidote, David J.; Russell, Rick; Lambowitz, Alan M.

    2013-01-01

    Mobile group II introns are bacterial retrotransposons thought to be evolutionary ancestors of spliceosomal introns and retroelements in eukaryotes. They consist of a catalytically active intron RNA (“ribozyme”) and an intron-encoded reverse transcriptase, which function together to promote RNA splicing and intron mobility via reverse splicing of the intron RNA into new DNA sites (“retrohoming”). Although group II introns are active in bacteria, their natural hosts, they function inefficiently in eukaryotes, where lower free Mg2+ concentrations decrease their ribozyme activity and constitute a natural barrier to group II intron proliferation within nuclear genomes. Here, we show that retrohoming of the Ll.LtrB group II intron is strongly inhibited in an Escherichia coli mutant lacking the Mg2+ transporter MgtA, and we use this system to select mutations in catalytic core domain V (DV) that partially rescue retrohoming at low Mg2+ concentrations. We thus identified mutations in the distal stem of DV that increase retrohoming efficiency in the MgtA mutant up to 22-fold. Biochemical assays of splicing and reverse splicing indicate that the mutations increase the fraction of intron RNA that folds into an active conformation at low Mg2+ concentrations, and terbium-cleavage assays suggest that this increase is due to enhanced Mg2+ binding to the distal stem of DV. Our findings indicate that DV is involved in a critical Mg2+-dependent RNA folding step in group II introns and demonstrate the feasibility of selecting intron variants that function more efficiently at low Mg2+ concentrations, with implications for evolution and potential applications in gene targeting. PMID:24043808

  15. Density functional formulation of the random-phase approximation for inhomogeneous fluids: Application to the Gaussian core and Coulomb particles

    NASA Astrophysics Data System (ADS)

    Frydel, Derek; Ma, Manman

    2016-06-01

    Using the adiabatic connection, we formulate the free energy in terms of the correlation function of a fictitious system, hλ(r ,r') , in which interactions λ u (r ,r') are gradually switched on as λ changes from 0 to 1. The function hλ(r ,r') is then obtained from the inhomogeneous Ornstein-Zernike equation and the two equations constitute a general liquid-state framework for treating inhomogeneous fluids. The two equations do not yet constitute a closed set. In the present work we use the closure cλ(r ,r') ≈-λ β u (r ,r') , known as the random-phase approximation (RPA). We demonstrate that the RPA is identical with the variational Gaussian approximation derived within the field-theoretical framework, originally derived and used for charged particles. We apply our generalized RPA approximation to the Gaussian core model and Coulomb charges.

  16. Silicate core-organic refractory mantle particles as interstellar dust and as aggregated in comets and stellar disks.

    PubMed

    Greenberg, J M; Li, A

    1997-01-01

    The principal observational properties of silicate core-organic refractory mantle interstellar dust grains in the infrared at 3.4 microns and at 10 microns and 20 microns are discussed in terms of the cyclic evolution of particles forming in stellar atmospheres and undergoing subsequent accretion, photoprocessing and destruction (erosion). Laboratory plus space emulation of the photoprocessing of laboratory analog ices and refractories are discussed. The aggregated interstellar dust model of comets is summarized. The same properties required to explain the temperature and infrared properties of comet coma dust are shown to be needed to account for the infrared silicate and continuum emission of the beta Pictoris disk as produced by a cloud of comets orbiting the star.

  17. Polymer blend particles with defined compositions for targeting antigen to both class I and II antigen presentation pathways.

    PubMed

    Tran, Kenny K; Zhan, Xi; Shen, Hong

    2014-05-01

    Defense against many persistent and difficult-to-treat diseases requires a combination of humoral, CD4(+) , and CD8(+) T-cell responses, which necessitates targeting antigens to both class I and II antigen presentation pathways. In this study, polymer blend particles are developed by mixing two functionally unique polymers, poly(lactide-co-glycolide) (PLGA) and a pH-responsive polymer, poly(dimethylaminoethyl methacrylate-co-propylacrylic acid-co-butyl methacrylate) (DMAEMA-co-PAA-co-BMA). Polymer blend particles are shown to enable the delivery of antigens into both class I and II antigen presentation pathways in vitro. Increasing the ratio of the pH-responsive polymer in blend particles increases the degree of class I antigen presentation, while maintaining high levels of class II antigen presentation. In a mouse model, it is demonstrated that a significantly higher and sustained level of CD4(+) and CD8(+) T-cell responses, and comparable antibody responses, are elicited with polymer blend particles than PLGA particles and a conventional vaccine, Alum. The polymer blend particles offer a potential vaccine delivery platform to generate a combination of humoral and cell-mediated immune responses that insure robust and long-lasting immunity against many infectious diseases and cancers.

  18. Screen of multifunctional monoclonal antibodies against hepatitis B core virus-like particles.

    PubMed

    Sun, Chang; Ding, Fei-Xiang; Wang, Fang; He, Xiao-Wen; He, Ying; Li, Zhao-Shen; Sun, Shu-Han

    2009-06-01

    HBc-VLP can be used in an epitope presentation system to carry foreign epitopes and mimic live virus in order to study viral particle uptake, virion-mediated activation and antigen presentation by dendritic cells. In this study, a multifunctional mAb was produced using a novel research strategy. A truncated HBc-VLP bone vector with a special conformation was used as an immunogen and the target hybridoma cell lines were screened by a series of tests; including ELISA, Western blot, and cellular immunofluorescence based on the epitope presentation system. The screened monoclonal antibody was used to identify the HBc-VLP vector, a fusion HBc-VLP vaccine, and intracellular HBV capsids. The new strategy facilitated acquisition of the desired mAbs and will serve as a reference for other VLP-related research.

  19. Nano-magnetic particles used in biomedicine: core and coating materials.

    PubMed

    Karimi, Z; Karimi, L; Shokrollahi, H

    2013-07-01

    Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine.

  20. The mutable nature of particle-core excitations with spin in the one-valence-proton nucleus 133Sb

    NASA Astrophysics Data System (ADS)

    Bocchi, G.; Leoni, S.; Fornal, B.; Colò, G.; Bortignon, P. F.; Bottoni, S.; Bracco, A.; Michelagnoli, C.; Bazzacco, D.; Blanc, A.; de France, G.; Jentschel, M.; Köster, U.; Mutti, P.; Régis, J.-M.; Simpson, G.; Soldner, T.; Ur, C. A.; Urban, W.; Fraile, L. M.; Lozeva, R.; Belvito, B.; Benzoni, G.; Bruce, A.; Carroll, R.; Cieplicka-Oryǹczak, N.; Crespi, F. C. L.; Didierjean, F.; Jolie, J.; Korten, W.; Kröll, T.; Lalkovski, S.; Mach, H.; Mărginean, N.; Melon, B.; Mengoni, D.; Million, B.; Nannini, A.; Napoli, D.; Olaizola, B.; Paziy, V.; Podolyák, Zs.; Regan, P. H.; Saed-Samii, N.; Szpak, B.; Vedia, V.

    2016-09-01

    The γ-ray decay of excited states of the one-valence-proton nucleus 133Sb has been studied using cold-neutron induced fission of 235U and 241Pu targets, during the EXILL campaign at the ILL reactor in Grenoble. By using a highly efficient HPGe array, coincidences between γ-rays prompt with the fission event and those delayed up to several tens of microseconds were investigated, allowing to observe, for the first time, high-spin excited states above the 16.6 μs isomer. Lifetimes analysis, performed by fast-timing techniques with LaBr3(Ce) scintillators, revealed a difference of almost two orders of magnitude in B(M1) strength for transitions between positive-parity medium-spin yrast states. The data are interpreted by a newly developed microscopic model which takes into account couplings between core excitations (both collective and non-collective) of the doubly magic nucleus 132Sn and the valence proton, using the Skyrme effective interaction in a consistent way. The results point to a fast change in the nature of particle-core excitations with increasing spin.

  1. Core-ion temperature measurement of the ADITYA tokamak using passive charge exchange neutral particle energy analyzer.

    PubMed

    Pandya, Santosh P; Ajay, Kumar; Mishra, Priyanka; Dhingra, Rajani D; Govindarajan, J

    2013-02-01

    Core-ion temperature measurements have been carried out by the energy analysis of passive charge exchange (CX) neutrals escaping out of the ADITYA tokamak plasma (minor radius, a = 25 cm and major radius, R = 75 cm) using a 45° parallel plate electrostatic energy analyzer. The neutral particle analyzer (NPA) uses a gas cell configuration for re-ionizing the CX-neutrals and channel electron multipliers (CEMs) as detectors. Energy calibration of the NPA has been carried out using ion-source and ΔE∕E of high-energy channel has been found to be ∼10%. Low signal to noise ratio (SNR) due to VUV reflections on the CEMs was identified during the operation of the NPA with ADITYA plasma discharges. This problem was rectified by upgrading the system by incorporating the additional components and arrangements to suppress VUV radiations and improve its VUV rejection capabilities. The noise rejection capability of the NPA was experimentally confirmed using a standard UV-source and also during the plasma discharges to get an adequate SNR (>30) at the energy channels. Core-ion temperature Ti(0) during flattop of the plasma current has been measured to be up to 150 eV during ohmically heated plasma discharges which is nearly 40% of the average core-electron temperature (typically Te(0) ∼ 400 eV). The present paper describes the principle of tokamak ion temperature measurement, NPA's design, development, and calibration along with the modifications carried out for minimizing the interference of plasma radiations in the CX-spectrum. Performance of the NPA during plasma discharges and experimental results on the measurement of ion-temperature have also been reported here.

  2. The relationship of shock-associated kilometric radio emission with metric type II bursts and energetic particles

    NASA Technical Reports Server (NTRS)

    Kahler, S. W.; Cliver, E. W.; Cane, H. V.

    1986-01-01

    Shock-associated (SA) events from 1978 to 1982 are compared with metric type II bursts and solar energetic particle (SEP) events. Most metric type II bursts are not obviously associated with SA events at 1980 kHz. Metric type II bursts associated with magnetically well connected flares and SA emission are well correlated with SEP events; those without SA emission are poorly correlated with SEP events. The largest SEP events from flares at any longitude are well correlated with SAs. These results are consistent with the hypothesis that the escaping electrons giving rise to SA emission are accelerated in coronal shocks.

  3. Synthesis of polystyrene core/SiO2 shell composite particles and fabrication of SiO2 capsules out of them

    NASA Astrophysics Data System (ADS)

    Terekhin, V.

    2017-01-01

    Systemic studies on the dependence of the morphology of polystyrene core/SiO2 shell composite particles on the conditions of their fabrication have been performed. Spherical polystyrene particles synthesized in the presence of a cationic initiator of polymerization were used as cores. SiO2 shells were formed by modified Stober’s method. Exposure of the synthesized composite particles to high temperatures has been shown to cause destruction of their polystyrene core, thereby allowing the formation of mesoporous SiO2 capsules with a mean pore diameter of ~3 nm and specific surface area of ~270 m2/g. Model experiments on loading the SiO2 capsules with amoxicillin have been carried out. Spectrophotometry in the UV and visible spectral regions has been used to estimate the kinetics of amoxicillin release from the SiO2 capsules.

  4. Collapse and Fragmentation Models of Prolate Molecular Cloud Cores. II. Initial Differential Rotation

    NASA Astrophysics Data System (ADS)

    Di G. Sigalotti, Leonardo

    1998-05-01

    The prevalence of companions to pre-main-sequence stars and the emerging observational evidence for binary and multiple protostellar condensations suggest that fragmentation during protostellar collapse is a mechanism that may occur frequently in the star formation process. Here a second-order accurate hydrodynamic code has been used to investigate the gravitational (postmagnetic) collapse and fragmentation of low-mass (~1 M⊙), small (~0.05 pc) molecular cloud cores, starting from moderately centrally condensed (Gaussian), prolate (2:1 and 4:1 axial ratios) configurations with varying thermal energies (α) and degrees of differential rotation (ν = 1/3 and 2/3). To facilitate comparisons with previous collapse calculations of uniformly rotating prolate cloud cores (Sigalotti & Klapp), all the models were made to start with a ratio of rotational to gravitational energy of β ~ 0.036. The results indicate that prolate clouds are highly susceptible to binary fragmentation and that with respect to uniformly rotating initial conditions, differential rotation plays no role in either determining or enhancing fragmentation in initially slowly rotating clouds. In contrast to the fragmentation criteria previously established by Boss and Myhill, the results also indicate that clouds with α = 0.56 and varied prolateness collapse in a similar fashion, producing intermediate central condensations of oblate spheroidal shape before fragmenting into either a binary (2:1 clouds) or multiple protostellar core (4:1 clouds). The models with α <= 0.45 all produced binary systems after having formed intermediate central condensations, which might be of prolate ellipsoidal (2:1 clouds) or narrow cylindrical (4:1 clouds) shape. The mass and separation of the binary fragments increase with decreasing α and with an increase of both the degree of differential rotation and the cloud elongation. The results imply that for initial low β, the degree of cloud prolateness has a greater effect

  5. Bioinformatic Analysis of Plasma Apolipoproteins A-I and A-II Revealed Unique Features of A-I/A-II HDL Particles in Human Plasma

    PubMed Central

    Kido, Toshimi; Kurata, Hideaki; Kondo, Kazuo; Itakura, Hiroshige; Okazaki, Mitsuyo; Urata, Takeyoshi; Yokoyama, Shinji

    2016-01-01

    Plasma concentration of apoA-I, apoA-II and apoA-II-unassociated apoA-I was analyzed in 314 Japanese subjects (177 males and 137 females), including one (male) homozygote and 37 (20 males and 17 females) heterozygotes of genetic CETP deficiency. ApoA-I unassociated with apoA-II markedly and linearly increased with HDL-cholesterol, while apoA-II increased only very slightly and the ratio of apoA-II-associated apoA-I to apoA-II stayed constant at 2 in molar ratio throughout the increase of HDL-cholesterol, among the wild type and heterozygous CETP deficiency. Thus, overall HDL concentration almost exclusively depends on HDL with apoA-I without apoA-II (LpAI) while concentration of HDL containing apoA-I and apoA-II (LpAI:AII) is constant having a fixed molar ratio of 2 : 1 regardless of total HDL and apoA-I concentration. Distribution of apoA-I between LpAI and LpAI:AII is consistent with a model of statistical partitioning regardless of sex and CETP genotype. The analysis also indicated that LpA-I accommodates on average 4 apoA-I molecules and has a clearance rate indistinguishable from LpAI:AII. Independent evidence indicated LpAI:A-II has a diameter 20% smaller than LpAI, consistent with a model having two apoA-I and one apoA-II. The functional contribution of these particles is to be investigated. PMID:27526664

  6. Preparation by alkaline treatment and detailed characterisation of empty hepatitis B virus core particles for vaccine and gene therapy applications

    NASA Astrophysics Data System (ADS)

    Strods, Arnis; Ose, Velta; Bogans, Janis; Cielens, Indulis; Kalnins, Gints; Radovica, Ilze; Kazaks, Andris; Pumpens, Paul; Renhofa, Regina

    2015-06-01

    Hepatitis B virus (HBV) core (HBc) virus-like particles (VLPs) are one of the most powerful protein engineering tools utilised to expose immunological epitopes and/or cell-targeting signals and for the packaging of genetic material and immune stimulatory sequences. Although HBc VLPs and their numerous derivatives are produced in highly efficient bacterial and yeast expression systems, the existing purification and packaging protocols are not sufficiently optimised and standardised. Here, a simple alkaline treatment method was employed for the complete removal of internal RNA from bacteria- and yeast-produced HBc VLPs and for the conversion of these VLPs into empty particles, without any damage to the VLP structure. The empty HBc VLPs were able to effectively package the added DNA and RNA sequences. Furthermore, the alkaline hydrolysis technology appeared efficient for the purification and packaging of four different HBc variants carrying lysine residues on the HBc VLP spikes. Utilising the introduced lysine residues and the intrinsic aspartic and glutamic acid residues exposed on the tips of the HBc spikes for chemical coupling of the chosen peptide and/or nucleic acid sequences ensured a standard and easy protocol for the further development of versatile HBc VLP-based vaccine and gene therapy applications.

  7. Preparation by alkaline treatment and detailed characterisation of empty hepatitis B virus core particles for vaccine and gene therapy applications.

    PubMed

    Strods, Arnis; Ose, Velta; Bogans, Janis; Cielens, Indulis; Kalnins, Gints; Radovica, Ilze; Kazaks, Andris; Pumpens, Paul; Renhofa, Regina

    2015-06-26

    Hepatitis B virus (HBV) core (HBc) virus-like particles (VLPs) are one of the most powerful protein engineering tools utilised to expose immunological epitopes and/or cell-targeting signals and for the packaging of genetic material and immune stimulatory sequences. Although HBc VLPs and their numerous derivatives are produced in highly efficient bacterial and yeast expression systems, the existing purification and packaging protocols are not sufficiently optimised and standardised. Here, a simple alkaline treatment method was employed for the complete removal of internal RNA from bacteria- and yeast-produced HBc VLPs and for the conversion of these VLPs into empty particles, without any damage to the VLP structure. The empty HBc VLPs were able to effectively package the added DNA and RNA sequences. Furthermore, the alkaline hydrolysis technology appeared efficient for the purification and packaging of four different HBc variants carrying lysine residues on the HBc VLP spikes. Utilising the introduced lysine residues and the intrinsic aspartic and glutamic acid residues exposed on the tips of the HBc spikes for chemical coupling of the chosen peptide and/or nucleic acid sequences ensured a standard and easy protocol for the further development of versatile HBc VLP-based vaccine and gene therapy applications.

  8. Antiviral Activity of Gold/Copper Sulfide Core/Shell Nanoparticles against Human Norovirus Virus-Like Particles

    PubMed Central

    Broglie, Jessica Jenkins; Alston, Brittny; Yang, Chang; Ma, Lun; Adcock, Audrey F.; Chen, Wei; Yang, Liju

    2015-01-01

    Human norovirus is a leading cause of acute gastroenteritis worldwide in a plethora of residential and commercial settings, including restaurants, schools, and hospitals. Methods for easily detecting the virus and for treating and preventing infection are critical to stopping norovirus outbreaks, and inactivation via nanoparticles (NPs) is a more universal and attractive alternative to other physical and chemical approaches. Using norovirus GI.1 (Norwalk) virus-like particles (VLPs) as a model viral system, this study characterized the antiviral activity of Au/CuS core/shell nanoparticles (NPs) against GI.1 VLPs for the rapid inactivation of HuNoV. Inactivation of VLPs (GI.1) by Au/CuS NPs evaluated using an absorbance-based ELISA indicated that treatment with 0.083 μM NPs for 10 min inactivated ~50% VLPs in a 0.37 μg/ml VLP solution and 0.83 μM NPs for 10 min completely inactivated the VLPs. Increasing nanoparticle concentration and/or VLP-NP contact time significantly increased the virucidal efficacy of Au/CuS NPs. Changes to the VLP particle morphology, size, and capsid protein were characterized using dynamic light scattering, transmission electron microscopy, and Western blot analysis. The strategy reported here provides the first reported proof-of-concept Au/CuS NPs-based virucide for rapidly inactivating human norovirus. PMID:26474396

  9. Mantle formation, coagulation, and the origin of cloud/core shine. II. Comparison with observations

    NASA Astrophysics Data System (ADS)

    Ysard, N.; Köhler, M.; Jones, A.; Dartois, E.; Godard, M.; Gavilan, L.

    2016-04-01

    Context. Many dense interstellar clouds are observable in emission in the near-IR (J, H, and K photometric bands), commonly referred to as "Cloudshine", and in the mid-IR (Spitzer IRAC 3.6 and 4.5 μm bands), the so-called "Coreshine". These C-shine observations have usually been explained in terms of grain growth but no model has yet been able to self-consistently explain the dust spectral energy distribution from the near-IR to the submm. Aims: Our new core/mantle evolutionary dust model, The Heterogeneous dust Evolution Model at the IaS (THEMIS), has been shown to be valid in the far-IR and submm. We want to demonstrate its ability to reproduce the C-shine observations. Methods: Our starting point is a physically motivated core/mantle dust model. It consists of three dust populations: small poly-aromatic-rich carbon grains, bigger core/mantle grains with mantles of aromatic-rich carbon, and cores made of either amorphous aliphatic-rich carbon or amorphous silicate. Then, we assume an evolutionary path where these grains, when entering denser regions, may first form a second aliphatic-rich carbon mantle (coagulation of small grains, accretion of carbon from the gas phase), second coagulate together to form large aggregates, and third accrete gas phase molecules coating them with an ice mantle. To compute the corresponding dust emission and scattering, we use a 3D Monte Carlo radiative transfer code. Results: We show that our global evolutionary dust modelling approach THEMIS allows us to reproduce C-shine observations towards dense starless clouds. Dust scattering and emission is most sensitive to the cloud central density and to the steepness of the cloud density profile. Varying these two parameters leads to changes that are stronger in the near-IR, in both the C-shine intensity and profile. Conclusions: With a combination of aliphatic-rich mantle formation and low-level coagulation into aggregates, we can self-consistently explain the observed C-shine and far

  10. Search for lightly ionizing particles using CDMS-II data and fabrication of CDMS detectors with improved homogeneity in properties

    SciTech Connect

    Prasad, Kunj Bihari

    2013-12-01

    Fundamental particles are always observed to carry charges which are integral multiples of one-third charge of electron, e/3. While this is a well established experimental fact, the theoretical understanding for the charge quantization phenomenon is lacking. On the other hand, there exist numerous theoretical models that naturally allow for existence of particles with fractional electromagnetic charge. These particles, if existing, hint towards existence of physics beyond the standard model. Multiple high energy, optical, cosmological and astrophysical considerations restrict the allowable mass-charge parameter space for these fractional charges. Still, a huge unexplored region remains. The Cryogenic Dark Matter Search (CDMS-II), located at Soudan mines in northern Minnesota, employs germanium and silicon crystals to perform direct searches for a leading candidate to dark matter called Weakly Interacting Massive Particles (WIMPs). Alternately, the low detection threshold allows search for fractional electromagnetic-charged particles, or Lightly Ionizing Particles (LIPs), moving at relativistic speed. Background rejection is obtained by requiring that the magnitude and location of energy deposited in each detector be consistent with corresponding \\signatures" resulting from the passage of a fractionally charged particle. In this dissertation, the CDMS-II data is analyzed to search for LIPs, with an expected background of 0.078 0.078 events. No candidate events are observed, allowing exclusion of new parameter space for charges between e/6 and e/200.

  11. Glucose sensing through Fano resonances in mesoscale silica core-gold shell particles arrays

    NASA Astrophysics Data System (ADS)

    Pincella, Francesca; Huang, Zhiwei

    2016-03-01

    We report the development of a versatile, cheap and reusable plasmonic sensor able to detect glucose in the physiological concentration range by means of a simple label-free optical detection scheme. In order to achieve the aforementioned goal we applied a self-assembly deposition technique for the large-scale arraying of mesoscale gold nanoshell particles. Different from metallic nanospheres arrays, the localized surface plasmon resonances of gold nanoshells arrays extend in both the visible and near-infrared range, making them extremely promising for their use in biological media. Furthermore, the optical response of mesoscale gold nanoshells arrays showed another remarkable characteristic, which is the presence of various Fano resonances that have the advantage of enhancing the sensitivity of the plasmonic substrate to the external media thanks to their sharp features and increased spectral contrast. The plasmonic sensor was shown to have an extended working range with a good linear response for large refractive index shifts, where a bulk refractive index sensitivity of 0.93 RIU-1 (RIU, refractive index units) was achieved experimentally. In addition, the plasmonic sensor could detect aqueous glucose solutions in the blood concentration range (0-25 mM), with a sensitivity of 0.24 M-1.

  12. Preparation and characterization of polymer electrolyte membranes based on silicon-containing core-shell structured nanocomposite latex particles

    NASA Astrophysics Data System (ADS)

    Zhong, Shuangling; Sun, Chenggang; Gao, Yushan; Cui, Xuejun

    2015-09-01

    A series of silicon-containing core-shell structured polyacrylate/2-acrylamido-2-methyl-1-propanesulfonic acid (SiO2-CS-PA/A) nanocomposite latex particles are prepared by the emulsifier-free emulsion polymerization of acrylate monomers and various amount of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) with colloidal nanosilica particles as seed. The chemical and morphological structures of latex particles with high monomer conversion are determined using Fourier transform infrared (FTIR), dynamic light scattering (DLS) and transmission electron microscopy (TEM). The SiO2-CS-PA/A nanocomposite membranes are fabricated through pouring the latex onto a clean surface of glass and drying at 60 °C for 10 h and 120 °C for 2 h. The nanocomposite membranes possess good thermal and dimensional stability. In addition, in comparison to Nafion® 117, the nanocomposite membranes exhibit moderate proton conductivity, significantly better methanol barrier and selectivity. The methanol diffusion coefficient is in the range of 1.03 × 10-8 to 5.26 × 10-8 cm2 s-1 which is about two orders of magnitude lower than that of Nafion® 117 (2.36 × 10-6 cm2 s-1). The SiO2-CS-PA/A 5 membrane shows the highest selectivity value (2.34 × 105 S cm-3) which is approximately 11.0 times of that (2.13 × 104 S cm-3) of Nafion® 117. These results indicate that the nanocomposite membranes are promising candidates to be used as polymer electrolyte membranes in direct methanol fuel cells.

  13. Wrinkle-assisted linear assembly of hard-core/soft-shell particles: impact of the soft shell on the local structure.

    PubMed

    Müller, Mareen; Karg, Matthias; Fortini, Andrea; Hellweg, Thomas; Fery, Andreas

    2012-04-07

    This article addresses wrinkle assisted assembly of core-shell particles with hard cores and soft poly-(N-isopropylacrylamide) shells. As core materials we chose silica as well as silver nanoparticles. The assembled structures show that the soft shells act as a separator between the inorganic cores. Anisotropic alignment is found on two length scales, macroscopically guided through the wrinkle structure and locally due to deformation of the polymer shell leading to smaller inter-core separations as compared to assembly on flat substrates without confinement. The structures were analysed by means of scanning electron microscopy. Radial distribution functions are shown, clearly highlighting the impact of confinement on nearest neighbour distances and symmetry. The observed ordering is directly compared to Monte-Carlo simulations for hard-core/soft-shell particles, showing that the observed symmetries are a consequence of the soft interaction potential and differ qualitatively from a hard-sphere situation. For the silver-poly-(N-isopropylacrylamide) particles, we show UV-vis absorbance measurements revealing optical anisotropy of the generated structures due to plasmon coupling. Furthermore, the high degree of order of the assembled structures on macroscopic areas is demonstrated by laser diffraction effects.

  14. Biomimetic synthesis of raspberry-like hybrid polymer-silica core-shell nanoparticles by templating colloidal particles with hairy polyamine shell.

    PubMed

    Pi, Mengwei; Yang, Tingting; Yuan, Jianjun; Fujii, Syuji; Kakigi, Yuichi; Nakamura, Yoshinobu; Cheng, Shiyuan

    2010-07-01

    The nanoparticles composed of polystyrene core and poly[2-(diethylamino)ethyl methacrylate] (PDEA) hairy shell were used as colloidal templates for in situ silica mineralization, allowing the well-controlled synthesis of hybrid silica core-shell nanoparticles with raspberry-like morphology and hollow silica nanoparticles by subsequent calcination. Silica deposition was performed by simply stirring a mixture of the polymeric core-shell particles in isopropanol, tetramethyl orthosilicate (TMOS) and water at 25 degrees C for 2.5h. No experimental evidence was found for nontemplated silica formation, which indicated that silica deposition occurred exclusively in the PDEA shell and formed PDEA-silica hybrid shell. The resulting hybrid silica core-shell particles were characterized by transmission electron microscopy (TEM), thermogravimetry, aqueous electrophoresis, and X-ray photoelectron spectroscopy. TEM studies indicated that the hybrid particles have well-defined core-shell structure with raspberry morphology after silica deposition. We found that the surface nanostructure of hybrid nanoparticles and the composition distribution of PDEA-silica hybrid shell could be well controlled by adjusting the silicification conditions. These new hybrid core-shell nanoparticles and hollow silica nanoparticles would have potential applications for high-performance coatings, encapsulation and delivery of active organic molecules.

  15. Water formation in early solar nebula: II-Collapsing cloud core

    NASA Astrophysics Data System (ADS)

    Tornow, C.; Gast, P.; Motschmann, U.; Kupper, S.; Kührt, E.; Pelivan, I.

    2014-08-01

    The formation of water is a repetitive process and depends on the physical conditions in the different stages of the solar nebula and early solar system. Our solar nebula model considers the thermal and chemical evolution of a collapsing globular cloud core. We simulate the collapse with a semi-analytical model which is based on a multi-zone density distribution. This model describes the formation of a central protostellar object surrounded by a disk and a thin outer envelope. It considers an adiabatic equation of state, viscous gas flow and a resistive magnetic field. Due to the low temperatures in the hydrostatic stage of the core, icy layers of water mixed with other molecules build on the dust grains. In the course of the collapse the ice sublimates and drives a complex chemical evolution located in a warm region around the proto-stellar object called hot corino. Moreover, the relatively high temperatures in this region allow the gas phase formation of water together with other molecules. The abundances of the chemical compounds are computed from rate equations solved in a Lagrangian grid. We can show that there was high water density in the early and late accretion zone of the Earth. This water was sublimated from the dust or formed by hot neutral reactions in the gas phase. Thus, according to our collapse model, there were two sources delivering the water incorporated into the Earth.

  16. The lithium isotope ratio in Population II halo dwarfs - A proposed test of the late decaying massive particle nucleosynthesis scenario

    NASA Technical Reports Server (NTRS)

    Brown, Lawrence; Schramm, David N.

    1988-01-01

    It is shown that observations of the lithium isotope ratio in high surface temperature Population II stars may be critical to cosmological nucleosynthesis models. In particular, decaying particle scenarios as derived in some supersymmetric models may stand or fall with such observations.

  17. Evaluation of Stability and Transient Characteristics of ABWR-II Large Bundle Core and SSR Influence for Transient phenomena by TRACG Code

    SciTech Connect

    Masao, Chaki; Hideo, Soneda; Shinya, Mizokami; Hideya, Kitamura; Kouji, Hiraiwa; Takanori, Fukahori; Andersen, Jens G.

    2004-07-01

    The next generation ABWR, the ABWR-II, has been under development for more than a decade in Japan. Among various features newly adopted for the ABWR-II, a 1.5 times lager fuel bundle is notable. This bundle design makes it possible to increase the total number of fuel rods in the core while minimizing the reactor pressure vessel size increase. As a result, the void coefficient is more negative due to the harder neutron spectrum since a smaller hydrogen-to uranium (H/U) ratio with fuel inventory increase makes the neutron spectrum harder. This more negative void coefficient affects the stability and transient characteristics of the ABWR-II plant. We have evaluated the stability and transient characteristics by using analysis codes and proven that these characteristics do not affect the realization of the ABWR-II large bundle core concept. Furthermore, we have evaluated the influences for the stability and transient phenomena by using spectral shift rods (SSRs) for the ABWR-II core. The analytical results show that the use of SSRs increases the design margin for the core stability. Regarding transient phenomena, the analyses by the TRACG code show that the influence of using SSRs is very small and do not affect the realization of the ABWR-II plant. In addition, the sensitivity analyses with the TRACG code show that design parameters of SSRs, inlet hole diameter of ascending path etc, are not very sensitive for the transient phenomena. (authors)

  18. Facile fabrication of core-shell structured magnetic Fe3O4/cross-linked polyphosphazene nanocomposite particles with high stability

    NASA Astrophysics Data System (ADS)

    Wang, Xuzhe; Wang, Minghuan; Fu, Jianwei; Zhang, Chao; Xu, Qun

    2013-08-01

    We herein report a facile approach to the fabrication of core-shell structured magnetic Fe3O4/poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) nanocomposite particles via precipitation polymerization of comonomers hexachlorocyclotriphosphazene and 4,4'-sulfonyldiphenol in the presence of Fe3O4 nanopaticles. The morphology, composition, thermal property, and magnetic property of the magnetic nanocomposite particles were characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectra, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer, respectively. Results indicated that the submicron-sized magnetic nanocomposite particles own core/shell structures, 410 °C of initial decomposition temperature under an air atmosphere, and 6.2 emu/g of saturation magnetization, which should make them have potential applications in biotechnology and catalyst supports. Furthermore, we also proposed a possible formation mechanism of these magnetic Fe3O4/PZS nanocomposite particles.

  19. Computational investigation of longitudinal diffusion, eddy dispersion, and trans-particle mass transfer in bulk, random packings of core-shell particles with varied shell thickness and shell diffusion coefficient.

    PubMed

    Daneyko, Anton; Hlushkou, Dzmitry; Baranau, Vasili; Khirevich, Siarhei; Seidel-Morgenstern, Andreas; Tallarek, Ulrich

    2015-08-14

    In recent years, chromatographic columns packed with core-shell particles have been widely used for efficient and fast separations at comparatively low operating pressure. However, the influence of the porous shell properties on the mass transfer kinetics in core-shell packings is still not fully understood. We report on results obtained with a modeling approach to simulate three-dimensional advective-diffusive transport in bulk random packings of monosized core-shell particles, covering a range of reduced mobile phase flow velocities from 0.5 up to 1000. The impact of the effective diffusivity of analyte molecules in the porous shell and the shell thickness on the resulting plate height was investigated. An extension of Giddings' theory of coupled eddy dispersion to account for retention of analyte molecules due to stagnant regions in porous shells with zero mobile phase flow velocity is presented. The plate height equation involving a modified eddy dispersion term excellently describes simulated data obtained for particle-packings with varied shell thickness and shell diffusion coefficient. It is confirmed that the model of trans-particle mass transfer resistance of core-shell particles by Kaczmarski and Guiochon [42] is applicable up to a constant factor. We analyze individual contributions to the plate height from different mass transfer mechanisms in dependence of the shell parameters. The simulations demonstrate that a reduction of plate height in packings of core-shell relative to fully porous particles arises mainly due to reduced trans-particle mass transfer resistance and transchannel eddy dispersion.

  20. Modeling the water circulation in the North Atlantic in the scope of the CORE-II experiment

    NASA Astrophysics Data System (ADS)

    Ushakov, K. V.; Grankina, T. B.; Ibraev, R. A.

    2016-07-01

    A numerical experiment on the reproduction of the variability in the state of North Atlantic water in 1948-2007 with a spatial resolution of 0.25° has been performed using the global ocean model developed at Institute of Numerical Mathematics, Russian Academy of Sciences (INM RAS), and the Shirshov Institute of Oceanology (IO RAS) (the INM-IO model). The data on the state of the atmosphere, radiation fluxes, and bulk formulas of the CORE-II protocol are used as boundary conditions. Five successive 60-year calculation cycles have been performed in order to obtain the quasi-equilibrium state of a model ocean. For the last 20 years, the main elements of large-scale ocean circulation have been analyzed and compared with the WOA09 atlas data and the results of other models.

  1. Effect of aggregation state, temperature and phospholipids on photobleaching of photosynthetic pigments in spinach Photosystem II core complexes.

    PubMed

    Ventrella, A; Catucci, L; Agostiano, A

    2008-06-01

    Photosystem II (PSII) complex activity is known to decrease under strong white light illumination, and this photoinhibition phenomenon is connected to the photobleaching of the PSII photosynthetic pigments. In this work the pigment photobleaching has been studied on PSII core complexes, by observing the effects of different factors such as the aggregation state (PSII monomers and dimers were used), temperature (20 degrees C and 10 degrees C temperatures were tested) and the presence of the exogenous phospholipids (cardiolipin and phosphatidylglycerol). In particular, PSII resistance against white light stress was studied by means of UV/VIS Absorption and Fluorescence Emission measurements. It was found that PSII dimers resulted more resistant against photobleaching and that lower temperature reduces the pigment photodestruction. Moreover, the presence of phosphatidylglycerol or cardiolipin enhanced the PSII resistance to the photobleaching phenomenon, mainly at lower temperatures.

  2. Fukushima Daiichi Unit 1 Uncertainty Analysis-Exploration of Core Melt Progression Uncertain Parameters-Volume II.

    SciTech Connect

    Denman, Matthew R.; Brooks, Dusty Marie

    2015-08-01

    Sandia National Laboratories (SNL) has conducted an uncertainty analysi s (UA) on the Fukushima Daiichi unit (1F1) accident progression wit h the MELCOR code. Volume I of the 1F1 UA discusses the physical modeling details and time history results of the UA. Volume II of the 1F1 UA discusses the statistical viewpoint. The model used was developed for a previous accident reconstruction investigation jointly sponsored by the US Department of Energy (DOE) and Nuclear Regulatory Commission (NRC). The goal of this work was to perform a focused evaluation of uncertainty in core damage progression behavior and its effect on key figures - of - merit (e.g., hydrogen production, fraction of intact fuel, vessel lower head failure) and in doing so assess the applicability of traditional sensitivity analysis techniques .

  3. Spectroscopic properties of the CP43 core antenna protein of photosystem II.

    PubMed

    Groot, M L; Frese, R N; de Weerd, F L; Bromek, K; Pettersson, A; Peterman, E J; van Stokkum, I H; van Grondelle, R; Dekker, J P

    1999-12-01

    CP43 is a chlorophyll-protein complex that funnels excitation energy from the main light-harvesting system of photosystem II to the photochemical reaction center. We purified CP43 from spinach photosystem II membranes in the presence of the nonionic detergent n-dodecyl-beta,D-maltoside and recorded its spectroscopic properties at various temperatures between 4 and 293 K by a number of polarized absorption and fluorescence techniques, fluorescence line narrowing, and Stark spectroscopy. The results indicate two "red" states in the Q(y) absorption region of the chlorophylls. The first peaks at 682.5 nm at 4 K, has an extremely narrow bandwidth with a full width at half-maximum of approximately 2.7 nm (58 cm(-1)) at 4 K, and has the oscillator strength of a single chlorophyll. The second peaks at approximately 679 nm, has a much broader bandshape, is caused by several excitonically interacting chlorophylls, and is responsible for all 4 K absorption at wavelengths longer than 685 nm. The Stark spectrum of CP43 resembles the first derivative of the absorption spectrum and has an exceptionally small overall size, which we attribute to opposing orientations of the monomer dipole moments of the excitonically coupled pigments.

  4. DIAGNOSING THE TIME DEPENDENCE OF ACTIVE REGION CORE HEATING FROM THE EMISSION MEASURE. II. NANOFLARE TRAINS

    SciTech Connect

    Reep, J. W.; Bradshaw, S. J.; Klimchuk, J. A. E-mail: stephen.bradshaw@rice.edu

    2013-02-20

    The time dependence of heating in solar active regions can be studied by analyzing the slope of the emission measure distribution coolward of the peak. In a previous study we showed that low-frequency heating can account for 0% to 77% of active region core emission measures. We now turn our attention to heating by a finite succession of impulsive events for which the timescale between events on a single magnetic strand is shorter than the cooling timescale. We refer to this scenario as a 'nanoflare train' and explore a parameter space of heating and coronal loop properties with a hydrodynamic model. Our conclusions are (1) nanoflare trains are consistent with 86% to 100% of observed active region cores when uncertainties in the atomic data are properly accounted for; (2) steeper slopes are found for larger values of the ratio of the train duration {Delta} {sub H} to the post-train cooling and draining timescale {Delta} {sub C}, where {Delta} {sub H} depends on the number of heating events, the event duration and the time interval between successive events ({tau} {sub C}); (3) {tau} {sub C} may be diagnosed from the width of the hot component of the emission measure provided that the temperature bins are much smaller than 0.1 dex; (4) the slope of the emission measure alone is not sufficient to provide information about any timescale associated with heating-the length and density of the heated structure must be measured for {Delta} {sub H} to be uniquely extracted from the ratio {Delta} {sub H}/{Delta} {sub C}.

  5. CALTECH CORE-COLLAPSE PROJECT (CCCP) OBSERVATIONS OF TYPE II SUPERNOVAE: EVIDENCE FOR THREE DISTINCT PHOTOMETRIC SUBTYPES

    SciTech Connect

    Arcavi, Iair; Gal-Yam, Avishay; Yaron, Ofer; Cenko, S. Bradley; Becker, Adam B.; Fox, Derek B.; Leonard, Douglas C.; Moon, Dae-Sik; Sand, David J.; Soderberg, Alicia M.; Kiewe, Michael; Scheps, Raphael; Birenbaum, Gali; Chamudot, Daniel; Zhou, Jonathan

    2012-09-10

    We present R-band light curves of Type II supernovae (SNe) from the Caltech Core-Collapse Project (CCCP). With the exception of interacting (Type IIn) SNe and rare events with long rise times, we find that most light curve shapes belong to one of three apparently distinct classes: plateau, slowly declining, and rapidly declining events. The last class is composed solely of Type IIb SNe which present similar light curve shapes to those of SNe Ib, suggesting, perhaps, similar progenitor channels. We do not find any intermediate light curves, implying that these subclasses are unlikely to reflect variance of continuous parameters, but rather might result from physically distinct progenitor systems, strengthening the suggestion of a binary origin for at least some stripped SNe. We find a large plateau luminosity range for SNe IIP, while the plateau lengths seem rather uniform at approximately 100 days. As analysis of additional CCCP data goes on and larger samples are collected, demographic studies of core-collapse SNe will likely continue to provide new constraints on progenitor scenarios.

  6. Widespread Use of TATA Elements in the Core Promoters for RNA Polymerases III, II, and I in Fission Yeast

    PubMed Central

    Hamada, Mitsuhiro; Huang, Ying; Lowe, Todd M.; Maraia, Richard J.

    2001-01-01

    In addition to directing transcription initiation, core promoters integrate input from distal regulatory elements. Except for rare exceptions, it has been generally found that eukaryotic tRNA and rRNA genes do not contain TATA promoter elements and instead use protein-protein interactions to bring the TATA-binding protein (TBP), to the core promoter. Genomewide analysis revealed TATA elements in the core promoters of tRNA and 5S rRNA (Pol III), U1 to U5 snRNA (Pol II), and 37S rRNA (Pol I) genes in Schizosaccharomyces pombe. Using tRNA-dependent suppression and other in vivo assays, as well as in vitro transcription, we demonstrated an obligatory requirement for upstream TATA elements for tRNA and 5S rRNA expression in S. pombe. The Pol III initiation factor Brf is found in complexes with TFIIIC and Pol III in S. pombe, while TBP is not, consistent with independent recruitment of TBP by TATA. Template commitment assays are consistent with this and confirm that the mechanisms of transcription complex assembly and initiation by Pol III in S. pombe differ substantially from those in other model organisms. The results were extended to large-rRNA synthesis, as mutation of the TATA element in the Pol I promoter also abolishes rRNA expression in fission yeast. A survey of other organisms' genomes reveals that a substantial number of eukaryotes may use widespread TATAs for transcription. These results indicate the presence of TATA-unified transcription systems in contemporary eukaryotes and provide insight into the residual need for TBP by all three Pols in other eukaryotes despite a lack of TATA elements in their promoters. PMID:11564871

  7. Particle identification with the TOP and ARICH detectors at Belle II

    NASA Astrophysics Data System (ADS)

    Torassa, E.

    2016-07-01

    The SuperKEKB e+e- collider will provide 40 times higher instantaneous luminosity than the KEKB collider. The Belle II detector, located at the collision point, is the upgrade of the Belle detector. The particle identification will be improved by replacing the aerogel threshold counter with two new high performance Cherenkov detectors: the time-of-propagation (TOP) in the barrel region and the focusing aerogel (ARICH) in the forward region. The time-of-propagation sub-detector consists of quartz radiator bars and micro-channel plate photomultiplier tubes. The Cherenkov photons are produced and propagated through the quartz radiator, and after multiple internal reflections they are detected by the photomultiplier tubes. Photons with different Cherenkov angles reach different photomultiplier channels and arrive at different times. The time and the position convolution is used for the reconstruction of the Cherenkov angle. The focusing aerogel consists of a double layer aerogel radiator, an expansion volume and a photon detector. The aerogel thickness and the refractive indices of the two layers are optimized to focus the two light cones at the detection surface. The key features of these two detectors, the performance studies, and the construction progress are presented.

  8. Core-shell designs of photoluminescent nanodiamonds with porous silica coatings for bioimaging and drug delivery II: application.

    PubMed

    Prabhakar, Neeraj; Näreoja, Tuomas; von Haartman, Eva; Karaman, Didem Şen; Jiang, Hua; Koho, Sami; Dolenko, Tatiana A; Hänninen, Pekka E; Vlasov, Denis I; Ralchenko, Victor G; Hosomi, Satoru; Vlasov, Igor I; Sahlgren, Cecilia; Rosenholm, Jessica M

    2013-05-07

    Recent advances within materials science and its interdisciplinary applications in biomedicine have emphasized the potential of using a single multifunctional composite material for concurrent drug delivery and biomedical imaging. Here we present a novel composite material consisting of a photoluminescent nanodiamond (ND) core with a porous silica (SiO2) shell. This novel multifunctional probe serves as an alternative nanomaterial to address the existing problems with delivery and subsequent tracing of the particles. Whereas the unique optical properties of ND allows for long-term live cell imaging and tracking of cellular processes, mesoporous silica nanoparticles (MSNs) have proven to be efficient drug carriers. The advantages of both ND and MSNs were hereby integrated in the new composite material, ND@MSN. The optical properties provided by the ND core rendered the nanocomposite suitable for microscopy imaging in fluorescence and reflectance mode, as well as super-resolution microscopy as a STED label; whereas the porous silica coating provided efficient intracellular delivery capacity, especially in surface-functionalized form. This study serves as a demonstration how this novel nanomaterial can be exploited for both bioimaging and drug delivery for future theranostic applications.

  9. Multi-Model Comparison of Southern Ocean and Sea Ice Trends in CORE-II and CMIP5 Model

    NASA Astrophysics Data System (ADS)

    Downes, S. M.; Griffies, S. M.; Farneti, R.; Marsland, S. J.; Uotila, P.; Hogg, A.

    2014-12-01

    The Southern Ocean circulation, influenced by buoyancy, momentum and sea ice processes, varies on seasonal to centennial timescales. Incomplete spatio-temporal observations of the full ocean water column, overlying ocean-ice-atmosphere fluxes, and adjacent polar dynamics challenge our ability to model the Southern Ocean. However, several studies have indicated this region is particularly important in the evolving climate, including the anthropogenic influences. Models coherently capture large-scale Southern Ocean patterns, however it is the magnitude and location of these patterns that varies widely. In particular, difficulties with modelling of small scale processes remains an outstanding issue. Here we review the representation of the Southern Ocean circulation, including fluxes at the ocean-ice and ocean-atmosphere interfaces, in numerous coupled climate models from two international modeling efforts, namely the Coordinated Ocean-ice Reference Experiments Phase II (CORE-II) and Coupled Model Intercomparison Project Phase 5 (CMIP5). We focus on the relationships between large scale and mesoscale overturning circulation, formation of key water masses and the associated deep winter mixed layers, buoyancy and wind fluxes, and sea ice. We identify major uncertainties in the modelling of past, present and projected large-scale ocean processes, and provide insights for future modelling directions.

  10. Validation of the REBUS-3/RCT methodologies for EBR-II core-follow analysis

    SciTech Connect

    McKnight, R.D.

    1992-01-01

    One of the many tasks to be completed at EBR-2/FCF (Fuel Cycle Facility) regarding fuel cycle closure for the Integral Fast Reactor (IFR) is to develop and install the systems to be used for fissile material accountancy and control. The IFR fuel cycle and pyrometallurgical process scheme determine the degree of actinide of actinide buildup in the reload fuel assemblies. Inventories of curium, americium and neptunium in the fuel will affect the radiation and thermal environmental conditions at the fuel fabrication stations, the chemistry of reprocessing, and the neutronic performance of the core. Thus, it is important that validated calculational tools be put in place for accurately determining isotopic mass and neutronic inputs to FCF for both operational and material control and accountancy purposes. The primary goal of this work is to validate the REBUS-2/RCT codes as tools which can adequately compute the burnup and isotopic distribution in binary- and ternary-fueled Mark-3, Mark-4, and Mark-5 subassemblies. 6 refs.

  11. SIMMER-II: A computer program for LMFBR disrupted core analysis

    SciTech Connect

    Bohl, W.R.; Luck, L.B.

    1990-06-01

    SIMMER-2 (Version 12) is a computer program to predict the coupled neutronic and fluid-dynamics behavior of liquid-metal fast reactors during core-disruptive accident transients. The modeling philosophy is based on the use of general, but approximate, physics to represent interactions of accident phenomena and regimes rather than a detailed representation of specialized situations. Reactor neutronic behavior is predicted by solving space (r,z), energy, and time-dependent neutron conservation equations (discrete ordinates transport or diffusion). The neutronics and the fluid dynamics are coupled via temperature- and background-dependent cross sections and the reactor power distribution. The fluid-dynamics calculation solves multicomponent, multiphase, multifield equations for mass, momentum, and energy conservation in (r,z) or (x,y) geometry. A structure field with nine density and five energy components; a liquid field with eight density and six energy components; and a vapor field with six density and on energy component are coupled by exchange functions representing a modified-dispersed flow regime with a zero-dimensional intra-cell structure model.

  12. Incorporation of deoxyribonucleotides and ribonucleotides by a dNTP-binding cleft mutated reverse transcriptase in hepatitis B virus core particles

    SciTech Connect

    Kim, Hee-Young; Kim, Hye-Young; Jung, Jaesung; Park, Sun; Shin, Ho-Joon; Kim, Kyongmin

    2008-01-05

    Our recent observation that hepatitis B virus (HBV) DNA polymerase (P) might initiate minus-strand DNA synthesis without primer [Kim et al., (2004) Virology 322, 22-30], raised a possibility that HBV P protein may have the potential to function as an RNA polymerase. Thus, we mutated Phe 436, a bulky amino acid with aromatic side chain, at the putative dNTP-binding cleft in reverse transcriptase (RT) domain of P protein to smaller amino acids (Gly or Val), and examined RNA polymerase activity. HBV core particles containing RT dNTP-binding cleft mutant P protein were able to incorporate {sup 32}P-ribonucleotides, but not HBV core particles containing wild type (wt), priming-deficient mutant, or RT-deficient mutant P proteins. Since all the experiments were conducted with core particles isolated from transfected cells, our results indicate that the HBV RT mutant core particles containing RT dNTP-binding cleft mutant P protein could incorporate both deoxyribonucleotides and ribonucleotides in replicating systems.

  13. Dielectric response of II-VI semiconductor core-shell ensembles: Study of the lossless optical condition

    NASA Astrophysics Data System (ADS)

    de la Cruz, R. M.; Kanyinda-Malu, C.

    2014-09-01

    We theoretically investigate optical properties of II-VI core-shell distribution mixtures made of two type-I sized-nanoshells as a plausible negative dielectric function material. The nonlocal optical response of the semiconductor QD is described by using a resonant excitonic dielectric function, while the shell response is modeled with Demangeot formula. Achieving the zero-loss at an optical frequency ω, i.e., ɛeff =ɛeff‧ + iɛeff″ with ɛeff‧ < 0 and ɛeff″ = 0, is of fundamental importance in nanophotonics. Resonant states in semiconductors provide a source for negative dielectric function provided that the dipole strength and the oscillator density are adequate to offset the background. Furthermore, the semiconductor offers the prospect of pumping, either optically or electrically, to achieve a gain mechanism that can offset the loss. We analyse optimal conditions that must be satisfied to achieve semiconductor-based negative index materials. By comparing with II-VI semiconductor quantum dots (QDs) previously reported in the literature, the inclusion of phonon and shell contributions in the ɛeff along with the finite barrier Effective Mass Approximation (EMA) approach, we found similar qualitative behaviours for the ɛeff. The lossless optical condition along with ɛeff‧ < 0 is discussed in terms of sizes, volume fractions and embedding medium of the mixtures' distributions. Furthermore, we estimated optical power to maintain nanocrystals density in excited states and this value is less than that previously obtained in II-VI semiconductor QDs.

  14. Rapid Histone-Catalyzed DNA Lesion Excision and Accompanying Protein Modification in Nucleosomes and Nucleosome Core Particles.

    PubMed

    Weng, Liwei; Greenberg, Marc M

    2015-09-02

    C5'-Hydrogen atoms are frequently abstracted during DNA oxidation. The oxidized abasic lesion 5'-(2-phosphoryl-1,4-dioxobutane) (DOB) is an electrophilic product of the C5'-radical. DOB is a potent irreversible inhibitor of DNA polymerase β, and forms interstrand cross-links in free DNA. We examined the reactivity of DOB within nucleosomes and nucleosome core particles (NCPs), the monomeric component of chromatin. Depending upon the position at which DOB is generated within a NCP, it is excised from nucleosomal DNA at a rate 275-1500-fold faster than that in free DNA. The half-life of DOB (7.0-16.8 min) in NCPs is shorter than any other abasic lesion. DOB's lifetime in NCPs is also significantly shorter than the estimated lifetime of an abasic site within a cell, suggesting that the observed chemistry would occur intracellularly. Histones also catalyze DOB excision when the lesion is present in the DNA linker region of a nucleosome. Schiff-base formation between DOB and histone proteins is detected in nucleosomes and NCPs, resulting in pyrrolone formation at the lysine residues. The lysines modified by DOB are often post-translationally modified. Consequently, the histone modifications described herein could affect the regulation of gene expression and may provide a chemical basis for the cytotoxicity of the DNA damaging agents that produce this lesion.

  15. Chimeric Derivatives of Hepatitis B Virus Core Particles Carrying Major Epitopes of the Rubella Virus E1 Glycoprotein

    PubMed Central

    Skrastina, Dace; Petrovskis, Ivars; Petraityte, Rasa; Sominskaya, Irina; Ose, Velta; Liekniņa, Ilva; Bogans, Janis; Sasnauskas, Kestutis

    2013-01-01

    Three variants of the major rubella virus (RV) E1 protein virus-neutralizing epitope from position 214 to 285 were exposed on the hepatitis B virus (HBV) C-terminally truncated core (HBcΔ) in a virus-like particle (VLP) vector and were produced in Escherichia coli. All three chimeras demonstrated VLPs in bacterial cell lysates, but only HBcΔ-E1(245-285) demonstrated the correct VLP structure after purification. The other chimeras, HBcΔ-E1(214-285) and HBcΔ-E1(214-240), appeared after purification as non-VLP aggregates of 100 to 900 nm in diameter according to dynamic light scattering data. All three variants possessed the intrinsic antigenic activity of RV E1, since they were recognized by natural human anti-RV E1 antibodies and induced an anti-RV E1 response in mice. HBcΔ-E1(214-240) and HBcΔ-E1(245-285) can be regarded as prototypes for a putative RV vaccine because they were able to induce antibodies recognizing natural RV E1 protein in RV diagnostic kits. PMID:24006140

  16. N-terminal α7 deletion of the proteasome 20S core particle substitutes for yeast PI31 function.

    PubMed

    Yashiroda, Hideki; Toda, Yousuke; Otsu, Saori; Takagi, Kenji; Mizushima, Tsunehiro; Murata, Shigeo

    2015-01-01

    The proteasome core particle (CP) is a conserved protease complex that is formed by the stacking of two outer α-rings and two inner β-rings. The α-ring is a heteroheptameric ring of subunits α1 to α7 and acts as a gate that restricts entry of substrate proteins into the catalytic cavity formed by the two abutting β-rings. The 31-kDa proteasome inhibitor (PI31) was originally identified as a protein that binds to the CP and inhibits CP activity in vitro, but accumulating evidence indicates that PI31 is required for physiological proteasome activity. To clarify the in vivo role of PI31, we examined the Saccharomyces cerevisiae PI31 ortholog Fub1. Fub1 was essential in a situation where the CP assembly chaperone Pba4 was deleted. The lethality of Δfub1 Δpba4 was suppressed by deletion of the N terminus of α7 (α7ΔN), which led to the partial activation of the CP. However, deletion of the N terminus of α3, which activates the CP more efficiently than α7ΔN by gate opening, did not suppress Δfub1 Δpba4 lethality. These results suggest that the α7 N terminus has a role in CP activation different from that of the α3 N terminus and that the role of Fub1 antagonizes a specific function of the α7 N terminus.

  17. Induced self-energy on a static scalar charged particle in the spacetime of a global monopole with finite core

    NASA Astrophysics Data System (ADS)

    Barbosa, D.; de Freitas, U.; Bezerra de Mello, E. R.

    2011-03-01

    We analyze the induced self-energy and self-force on a scalar point-like charged test particle placed at rest in the spacetime of a global monopole admitting a general spherically symmetric inner structure to it. In order to develop this analysis we calculate the three-dimensional Green's function associated with this physical system. We explicitly show that for points outside the monopole's core the scalar self-energy presents two distinct contributions. The first one is induced by the non-trivial topology of the global monopole considered as a point-like defect and the second is a correction induced by the non-vanishing inner structure attributed to it. For points inside the monopole, the self-energy also present a similar structure, where now the first contribution depends on the geometry of the spacetime inside. As illustrations of the general procedure adopted, two specific models, namely flower-pot and the ballpoint-pen, are considered for the region inside. For these two different situations, we were able to obtain exact expressions for the self-energies and self-forces in the regions outside and inside the global monopole.

  18. Evaluation of SAGE II and Balloon-Borne Stratospheric Aerosol Measurements: Evaluation of Aerosol Measurements from SAGE II, HALOE, and Balloonborne Optical Particle Counters

    NASA Technical Reports Server (NTRS)

    Hervig, Mark; Deshler, Terry; Moddrea, G. (Technical Monitor)

    2002-01-01

    Stratospheric aerosol measurements from the University of Wyoming balloonborne optical particle counters (OPCs), the Stratospheric Aerosol and Gas Experiment (SAGE) II, and the Halogen Occultation Experiment (HALOE) were compared in the period 1982-2000, when measurements were available. The OPCs measure aerosol size distributions, and HALOE multiwavelength (2.45-5.26 micrometers) extinction measurements can be used to retrieve aerosol size distributions. Aerosol extinctions at the SAGE II wavelengths (0.386-1.02 micrometers) were computed from these size distributions and compared to SAGE II measurements. In addition, surface areas derived from all three experiments were compared. While the overall impression from these results is encouraging, the agreement can change with latitude, altitude, time, and parameter. In the broadest sense, these comparisons fall into two categories: high aerosol loading (volcanic periods) and low aerosol loading (background periods and altitudes above 25 km). When the aerosol amount was low, SAGE II and HALOE extinctions were higher than the OPC estimates, while the SAGE II surface areas were lower than HALOE and the OPCS. Under high loading conditions all three instruments mutually agree to within 50%.

  19. Ru(II) Tris(3,8-Dibromo-1,10-Phenanthro1ine): A New Versatile Core for the Divergent Synthesis of Hyperbranched Systems

    NASA Technical Reports Server (NTRS)

    Sotiriou-Leventis, Chariklia; Yang, Jinhua; Duan, Penggao; Leventis, Nicholas

    2004-01-01

    We report the first synthesis of Ru(II) tris(3,8-dibromo-1,lO-phenanthroline) bishexafluorophosphate, and we demonstrate its utility as a building core for the divergent synthesis of hyperbranched systems by coupling with phenylacetylene in the preparation of Rum tris(3,8-diphenylethynyl- 1,lO-phenanthroline) dihexafluorophosphate.

  20. Interface control of electronic and optical properties in IV-VI and II-VI core/shell colloidal quantum dots: a review.

    PubMed

    Jang, Youngjin; Shapiro, Arthur; Isarov, Maya; Rubin-Brusilovski, Anna; Safran, Aron; Budniak, Adam K; Horani, Faris; Dehnel, Joanna; Sashchiuk, Aldona; Lifshitz, Efrat

    2017-01-17

    Semiconductor colloidal quantum dots (CQDs) have attracted vast scientific and technological interest throughout the past three decades, due to the unique tuneability of their optoelectronic properties by variation of size and composition. However, the nanoscale size brings about a large surface-to-bulk volume ratio, where exterior surfaces have a pronounced influence on the chemical stability and on the physical properties of the semiconductor. Therefore, numerous approaches have been developed to gain efficient surface passivation, including a coverage by organic or inorganic molecular surfactants as well as the formation of core/shell heterostructures (a semiconductor core epitaxially covered by another semiconductor shell). This review focuses on special designs of core/shell heterostructures from the IV-VI and II-VI semiconductor compounds, and on synthetic approaches and characterization of the optical properties. Experimental observations revealed the formation of core/shell structures with type-I or quasi-type-II band alignment between the core and shell constituents. Theoretical calculations of the electronic band structures, which were also confirmed by experimental work, exposed surplus electronic tuning (beyond the radial diameter) with adaptation of the composition and control of the interface properties. The studies also considered strain effects that are created between two different semiconductors. It was disclosed experimentally and theoretically that the strain can be released via the formation of alloys at the core-shell interface. Overall, the core/shell and core/alloyed-shell heterostructures showed enhancement in luminescence quantum efficiency with respect to that of pure cores, extended lifetime, uniformity in size and in many cases good chemical sustainability under ambient conditions.

  1. Core phenomenology. TEC report on CRBRP PRA Phase II, Task 6C. Final draft report, Revision 1

    SciTech Connect

    1984-04-04

    As part of the determination of the risk potential associated with core-damage accident sequences for the CRBRP, a review of the core-damage phenomenology is necessary. How core damage proceeds, its effects on the primary system boundary, and the timing and energetic potential associated with core damage are important to determining the challenge to containment and the ultimate release of fission products to the environment. This chapter addresses the phenomenology related to the core-damage processes and by the use of a core-response event tree, estimates are made of the probability that certain core-response scenarios are followed.

  2. A new insight on the core-shell structure of zerovalent iron nanoparticles and its application for Pb(II) sequestration.

    PubMed

    Zhang, Yalei; Su, Yiming; Zhou, Xuefei; Dai, Chaomeng; Keller, Arturo A

    2013-12-15

    Nanoscale zerovalent iron (nZVI) has shown a high efficacy for removing heavy metals from liquid solution. However, its removal capacity has not been fully explored due to its common shell composition (FeOOH). In this study, a much higher removal capacity of Pb(II) is observed (1667 mg Pb(II)/gFe), which is over 100% higher than the highest removal capacity of nZVI reported before. High-resolution X-ray photoelectron spectroscopy (HR-XPS) reveals that through restricting the dehydration process of Fe(OH)3, nZVI can acquire a unique shell, which is composed of 45.5% Fe(OH)3 and 54.5% FeOOH. The presence of Fe(OH)3 suppresses the reduction of Pb(II), but greatly promotes the co-precipitation and adsorption of Pb(II). Combining the ratio of Fe-released to Pb-immobilized and the result of HR-XPS, a reaction between Fe(0) core, Fe(OH)3, and Pb(II) is proposed. The Fe released from the Fe(0) core leads to the core depletion, observed by transmission electron microscopy (TEM) under high Pb(II) loading. While temperature has little influence on the removal capacity, pH affects the removal capacity greatly. pH<4.5 favors Fe dissolution, while pH>4.5 promotes Pb(II) adsorption. Given the high Pb removal capacity via the Fe(OH)3 shell, nZVI can be used to remedy Pb(II) contamination.

  3. Primordial nucleosynthesis with decaying particles. I - Entropy-producing decays. II - Inert decays

    NASA Technical Reports Server (NTRS)

    Scherrer, Robert J.; Turner, Michael S.

    1988-01-01

    The effect of a nonrelativistic particle X, which decays out of equilibrium, on primordial nucleosynthesis is investigated, including both the energy density of the X particle and the electromagnetic entropy production from its decay. The results are parametrized in terms of the X particle lifetime and the density parameter rm(X), where m(X) is the X particle mass and r is the ratio of X number density to photon number density prior to nucleosynthesis. The results rule out particle lifetimes greater than 1-10 s for large values of rm(X). The question of a decaying particle which produces no electromagnetic entropy in the course of its decay is addressed, and particles which produce both entropy and an inert component in their decay are discussed.

  4. Backreaction of Tracer Particles on Vortex Tangle in Helium II Counterflow

    NASA Astrophysics Data System (ADS)

    Varga, E.; Barenghi, C. F.; Sergeev, Y. A.; Skrbek, L.

    2016-05-01

    We report computer simulations of the interaction of seeding particles with quantized vortices and with the normal fluid flow in thermal counterflow of superfluid ^4He. We show that if the number of particles is too large, the vortex tangle is significantly affected, posing problems in the interpretation of visualization experiments. The main effects are an increase in vortex line density and a change in polarization of the vortex tangle, caused by the action of the Stokes drag of the viscous normal fluid on the trapped particles. We argue that in the case of large particle number, typically used for the particle image velocimetry technique, the tangle properties might become significantly changed. On the contrary, the particle tracking velocimetry technique that uses smaller particle concentration should not be appreciably affected.

  5. Inhibitory effect of presenilin inhibitor LY411575 on maturation of hepatitis C virus core protein, production of the viral particle and expression of host proteins involved in pathogenicity.

    PubMed

    Otoguro, Teruhime; Tanaka, Tomohisa; Kasai, Hirotake; Yamashita, Atsuya; Moriishi, Kohji

    2016-11-01

    Hepatitis C virus (HCV) core protein is responsible for the formation of infectious viral particles and induction of pathogenicity. The C-terminal transmembrane region of the immature core protein is cleaved by signal peptide peptidase (SPP) for maturation of the core protein. SPP belongs to the family of presenilin-like aspartic proteases. Some presenilin inhibitors are expected to suppress HCV infection and production; however, this anti-HCV effect has not been investigated in detail. In this study, presenilin inhibitors were screened to identify anti-HCV compounds. Of the 13 presenilin inhibitors tested, LY411575 was the most potent inhibitor of SPP-dependent cleavage of HCV core protein. Production of intracellular core protein and supernatant infectious viral particles from HCV-infected cells was significantly impaired by LY411575 in a dose-dependent manner (half maximum inhibitory concentration = 0.27 μM, cytotoxic concentration of the extracts to cause death to 50% of viable cells > 10 μM). No effect of LY411575 on intracellular HCV RNA in the subgenomic replicon cells was detected. LY411575 synergistically promoted daclatasvir-dependent inhibition of viral production, but not that of viral replication. Furthermore, LY411575 inhibited HCV-related production of reactive oxygen species and expression of NADPH oxidases and vascular endothelial growth factor. Taken together, our data suggest that LY411575 suppresses HCV propagation through SPP inhibition and impairs host gene expressions related to HCV pathogenicity.

  6. Core-Shell Soy Protein-Soy Polysaccharide Complex (Nano)particles as Carriers for Improved Stability and Sustained Release of Curcumin.

    PubMed

    Chen, Fei-Ping; Ou, Shi-Yi; Tang, Chuan-He

    2016-06-22

    Using soy protein isolate (SPI) and soy-soluble polysaccharides (SSPS) as polymer matrixes, this study reported a novel process to fabricate unique core-shell complex (nano)particles to perform as carriers for curcumin (a typical poorly soluble bioactive). In the process, curcumin-SPI nanocomplexes were first formed at pH 7.0 and then coated by SSPS. At this pH, the core-shell complex was formed in a way the SPI nanoparticles might be incorporated into the interior of SSPS molecules without distinctly affecting the size and morphology of particles. The core-shell structure was distinctly changed by adjusting pH from 7.0 to 4.0. At pH 4.0, SSPS was strongly bound to the surface of highly aggregated SPI nanoparticles, and as a consequence, much larger complexes were formed. The bioaccessibility of curcumin in the SPI-curcumin complexes was unaffected by the SSPS coating. However, the core-shell complex formation greatly improved the thermal stability and controlled release properties of encapsulated curcumin. The improvement was much better at pH 4.0 than that at pH 7.0. All of the freeze-dried core-shell complex preparations exhibited good redispersion behavior. The findings provide a simple approach to fabricate food-grade delivery systems for improved water dispersion, heat stability, and even controlled release of poorly soluble bioactives.

  7. Removal of Cu(II) from aqueous solution using synthetic poly(catechol-diethylenetriamine-p-phenylenediamine) particles.

    PubMed

    Liu, Qiang; Liu, Qinze; Ruan, Zining; Chang, Xiaoqing; Yao, Jinshui

    2016-07-01

    A novel poly(catechol-diethylenetriamine-pphenylenediamine)(PCEA) adsorbent was synthesized in methanol, with chelating groups supplied by catechol and diethylenetriamine, which showed a strong removal performance and efficient adsorption toward Cu(II) ions in aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Besides, factors such as adsorbent dosage, pH, initial ionic and metal concentrations, contact time, and temperature on the adsorption of Cu(II) were studied. The data revealed that the adsorption followed a pseudo-second order kinetic model and the adsorption rate was influenced by the intra-particle diffusion. Furthermore, the adsorption process followed the Langmuir isotherm model, and the maximum adsorption capacity (Qm) was 44.2mg/g at 298K in simulated wastewater. The value of ΔG (kJ/mol) and ΔH (kJ/mol) also demonstrated that the adsorption process was spontaneous and endothermic. Studies revealed that PCEA particles were powerful and stable for the removal of Cu(II) in water, and it could be directly applied to the Cu(II)-contaminated water.

  8. CHARGED-PARTICLE AND NEUTRON-CAPTURE PROCESSES IN THE HIGH-ENTROPY WIND OF CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Farouqi, K.; Truran, J. W.; Kratz, K.-L.; Pfeiffer, B.; Rauscher, T.; Thielemann, F.-K. E-mail: truran@nova.uchicago.ed E-mail: k-l.Kratz@mpic.d E-mail: F-K.Thielemann@unibas.c

    2010-04-01

    The astrophysical site of the r-process is still uncertain, and a full exploration of the systematics of this process in terms of its dependence on nuclear properties from stability to the neutron drip-line within realistic stellar environments has still to be undertaken. Sufficiently high neutron-to-seed ratios can only be obtained either in very neutron-rich low-entropy environments or moderately neutron-rich high-entropy environments, related to neutron star mergers (or jets of neutron star matter) and the high-entropy wind of core-collapse supernova explosions. As chemical evolution models seem to disfavor neutron star mergers, we focus here on high-entropy environments characterized by entropy S, electron abundance Y{sub e} , and expansion velocity V{sub exp}. We investigate the termination point of charged-particle reactions, and we define a maximum entropy S{sub final} for a given V{sub exp} and Y{sub e} , beyond which the seed production of heavy elements fails due to the very small matter density. We then investigate whether an r-process subsequent to the charged-particle freeze-out can in principle be understood on the basis of the classical approach, which assumes a chemical equilibrium between neutron captures and photodisintegrations, possibly followed by a beta-flow equilibrium. In particular, we illustrate how long such a chemical equilibrium approximation holds, how the freeze-out from such conditions affects the abundance pattern, and which role the late capture of neutrons originating from beta-delayed neutron emission can play. Furthermore, we analyze the impact of nuclear properties from different theoretical mass models on the final abundances after these late freeze-out phases and beta-decays back to stability. As only a superposition of astrophysical conditions can provide a good fit to the solar r-abundances, the question remains how such superpositions are attained, resulting in the apparently robust r-process pattern observed in low

  9. Surface protein imprinted core-shell particles for high selective lysozyme recognition prepared by reversible addition-fragmentation chain transfer strategy.

    PubMed

    Li, Qinran; Yang, Kaiguang; Liang, Yu; Jiang, Bo; Liu, Jianxi; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2014-12-24

    A novel kind of lysozyme (Lys) surface imprinted core-shell particles was synthesized by reversible addition-fragmentation chain transfer (RAFT) strategy. With controllable polymer shell chain length, such particles showed obviously improved selectivity for protein recognition. After the RAFT initial agent and template protein was absorbed on silica particles, the prepolymerization solution, with methacrylic acid and 2-hydroxyethyl methacrylate as the monomers, and N,N'-methylenebis(acrylamide) as the cross-linker, was mixed with the silica particles, and the polymerization was performed at 40 °C in aqueous phase through the oxidation-reduction initiation. Ater polymerization, with the template protein removal and destroying dithioester groups with hexylamine, the surface Lyz imprinted particles were obtained with controllable polymer chain length. The binding capacity of the Lys imprinted particles could reach 5.6 mg protein/g material, with the imprinting factor (IF) as 3.7, whereas the IF of the control material prepared without RAFT strategy was only 1.6. The absorption equilibrium could be achieved within 60 min. Moreover, Lys could be selectively recognized by the imprinted particles from both a four-proteins mixture and egg white sample. All these results demonstrated that these particles prepared by RAFT strategy are promising to achieve the protein recognition with high selectivity.

  10. Rapid determination of parabens in seafood sauces by high-performance liquid chromatography: A practical comparison of core-shell particles and sub-2 μm fully porous particles.

    PubMed

    Ye, Jing; Cao, Xiaoji; Cheng, Zhuo; Qin, Ye; Lu, Yanbin

    2015-12-01

    In this work, the chromatographic performance of superficially porous particles (Halo core-shell C18 column, 50 mm × 2.1 mm, 2.7 μm) was compared with that of sub-2 μm fully porous particles (Acquity BEH C18 , 50 mm × 2.1 mm, 1.7 μm). Four parabens, methylparaben, ethylparaben, propylparaben, and butylparaben, were used as representative compounds for calculating the plate heights in a wide flow rate range and analyzed on the basis of the Van Deemter and Knox equations. Theoretical Poppe plots were constructed for each column to compare their kinetic performance. Both phases gave similar minimum plate heights when using nonreduced coordinates. Meanwhile, the flat C-term of the core-shell column provided the possibilities for applying high flow rates without significant loss in efficiency. The low backpressure of core-shell particles allowed this kind of column, especially compatible with conventional high-performance liquid chromatography systems. Based on these factors, a simple high-performance liquid chromatography method was established and validated for the determination of parabens in various seafood sauces using the Halo core-shell C18 column for separation.

  11. Hindered submicron mobility and long-term storage of presynaptic dense-core granules revealed by single-particle tracking.

    PubMed

    Scalettar, B A; Jacobs, C; Fulwiler, A; Prahl, L; Simon, A; Hilken, L; Lochner, J E

    2012-09-01

    Dense-core granules (DCGs) are organelles found in neuroendocrine cells and neurons that house, transport, and release a number of important peptides and proteins. In neurons, DCG cargo can include the secreted neuromodulatory proteins tissue plasminogen activator (tPA) and/or brain-derived neurotrophic factor (BDNF), which play a key role in modulating synaptic efficacy in the hippocampus. This function has spurred interest in DCGs that localize to synaptic contacts between hippocampal neurons, and several studies recently have established that DCGs localize to, and undergo regulated exocytosis from, postsynaptic sites. To complement this work, we have studied presynaptically localized DCGs in hippocampal neurons, which are much more poorly understood than their postsynaptic analogs. Moreover, to enhance relevance, we visualized DCGs via fluorescence labeling of exogenous and endogenous tPA and BDNF. Using single-particle tracking, we determined trajectories of more than 150 presynaptically localized DCGs. These trajectories reveal that mobility of DCGs in presynaptic boutons is highly hindered and that storage is long-lived. We also computed mean-squared displacement curves, which can be used to elucidate mechanisms of transport. Over shorter time windows, most curves are linear, demonstrating that DCG transport in boutons is driven predominantly by diffusion. The remaining curves plateau with time, consistent with motion constrained by a submicron-sized corral. These results have relevance to recent models of presynaptic organization and to recent hypotheses about DCG cargo function. The results also provide estimates for transit times to the presynaptic plasma membrane that are consistent with measured times for onset of neurotrophin release from synaptically localized DCGs.

  12. Atomistic Simulation of Stacked Nucleosome Core Particles: Tail Bridging, the H4 Tail, and Effect of Hydrophobic Forces.

    PubMed

    Saurabh, Suman; Glaser, Matthew A; Lansac, Yves; Maiti, Prabal K

    2016-03-31

    We report the first atomistic simulation of two stacked nucleosome core particles (NCPs), with an aim to understand, in molecular detail, how they interact, the effect of salt concentration, and how different histone tails contribute to their interaction, with a special emphasis on the H4 tail, known to have the largest stabilizing effect on the NCP-NCP interaction. We do not observe specific K16-mediated interaction between the H4 tail and the H2A-H2B acidic patch, in contrast with the findings from crystallographic studies, but find that the stacking was stable even in the absence of this interaction. We perform simulations with the H4 tail (partially/completely) removed and find that the region between LYS-16 and LYS-20 of the H4 tail holds special importance in mediating the inter-NCP interaction. Performing similar tail-clipped simulations with the H3 tail removed, we compare the roles of the H3 and H4 tails in maintaining the stacking. We discuss the relevance of our simulation results to the bilayer and other liquid-crystalline phases exhibited by NCPs in vitro and, through an analysis of the histone-histone interface, identify the interactions that could possibly stabilize the inter-NCP interaction in these columnar mesophases. Through the mechanical disruption of the stacked nucleosome system using steered molecular dynamics, we quantify the strength of inter-NCP stacking in the presence and absence of salt. We disrupt the stacking at some specific sites of internucleosomal tail-DNA contact and perform a comparative quantification of the binding strengths of various tails in stabilizing the stacking. We also examine how hydrophobic interactions may contribute to the overall stability of the stacking and find a marked difference in the role of hydrophobic forces as compared with electrostatic forces in determining the stability of the stacked nucleosome system.

  13. Mechanochemical surface functionalisation of superparamagnetic microparticles with in situ formed crystalline metal-complexes: a fast novel core-shell particle formation method.

    PubMed

    Brede, F A; Mandel, K; Schneider, M; Sextl, G; Müller-Buschbaum, K

    2015-05-21

    An innovative mechanochemical method is reported for the in situ formation of crystalline metal-complexes on the surface of superparamagnetic nanocomposite microparticles. The process is demonstrated for coating Fe3O4 multicore-silica matrix particles with the 1,2,4-1H-triazole complex [ZnCl2(TzH)2]. The use of mechanochemistry demonstrates a flexible process to obtain functional shells on magnetic particle cores without the need for complicated surface-functionalisation reactions in solution. Simple mixing of the desired shell-precursors ZnCl2 and 1,2,4-1H-triazole (TzH) with the magnetic particles in a ball mill is sufficient to tailor the particle surfaces with novel functionalities while retaining the superparamagnetic behaviour.

  14. Identifying the lowest electronic states of the chlorophylls in the CP47 core antenna protein of photosystem II.

    PubMed

    De Weerd, Frank L; Palacios, Miguel A; Andrizhiyevskaya, Elena G; Dekker, Jan P; Van Grondelle, Rienk

    2002-12-24

    CP47 is a pigment-protein complex in the core of photosystem II that tranfers excitation energy to the reaction center. Here we report on a spectroscopic investigation of the isolated CP47 complex. By deconvoluting the 77 K absorption and linear dichroism, red-most states at 683 and 690 nm have been identified with oscillator strengths corresponding to approximately 3 and approximately 1 chlorophyll, respectively. Both states contribute to the 4 K emission, and the Stark spectrum shows that they have a large value for the difference polarizability between their ground and excited states. From site-selective polarized triplet-minus-singlet spectra, an excitonic origin for the 683 nm state was found. The red shift of the 690 nm state is most probably due to strong hydrogen bonding to a protein ligand, as follows from the position of the stretch frequency of the chlorophyll 13(1) keto group (1633 cm(-)(1)) in the fluorescence line narrowing spectrum at 4 K upon red-most excitation. We discuss how the 683 and 690 nm states may be linked to specific chlorophylls in the crystal structure [Zouni, A., Witt, H.-T., Kern, J., Fromme, P., Krauss, N., Saenger, W., and Orth, P. (2001) Nature 409, 739-743].

  15. Uniform particle-droplet partitioning of 18 organic and elemental components measured in and below DYCOMS-II stratocumulus clouds

    NASA Astrophysics Data System (ADS)

    Hawkins, L. N.; Russell, L. M.; Twohy, C. H.; Anderson, J. R.

    2008-07-01

    Microphysical and chemical aerosol measurements collected during DYCOMS-II research flights in marine stratocumulus clouds near San Diego in 2001 were used to evaluate the partitioning of 18 organic and elemental components between droplet residuals and unactivated particles. Bulk submicron particle (between 0.2 and 1.3 μm dry diameter) and droplet residual (above 9 μm ambient diameter) filter samples analyzed by Fourier Transform Infrared (FTIR) spectroscopy and X-ray Fluorescence (XRF) were dominated by sea salt, ammonium, sulfate, and organic compounds. For the four nighttime and two daytime flights studied, the mass concentration of unactivated particles and droplet residuals were correlated (R2 > 0.8) with consistent linear relationships for mass scavenging of all 18 components on each flight, meaning that the measured particle population partitions between droplet residuals and unactivated particles as if the particles contain internal mixtures of the measured components. Scanning electron microscopy (SEM) for flights 3, 5, and 7 support some degree of internal mixing since more than 90% of measured submicron particles larger than 0.26 μm included sea salt-derived components. The observed range of 0.26 to 0.40 of mass scavenging coefficients for the four nighttime flights results from the small variations in temperature profile, updraft velocity, and mixed layer depth among the flights. The uniformity of scavenging coefficients for multiple chemical components is consistent with the aged or processed internal mixtures of sea salt, sulfate, and organic compounds expected at long distances downwind from major particle sources.

  16. Comparing addition of ZrO II particles in micron and nano scale on microstructure and mechanical behavior of aluminum-matrix composites produced by vortex route

    NASA Astrophysics Data System (ADS)

    Baghchesara, M. A.; Karimi, M.; Abdizadeh, H.; Baharvandi, H. R.

    2007-07-01

    Aluminum matrix composites are important engineering materials in automotive, aerospace and other applications because of their low weight, high specific strength and better physical and mechanical properties compared to pure aluminum. ZrO II particles as reinforcement were selected to add aluminum with micron and nano size. Al/ZrO II composites were produced by direct incorporation (vortex method) in different temperatures and 5 volume percents of ZrO II particles. Microstructure of the samples was studied by scanning electron microscopy (SEM). Chemical composition of the phases was studied by XRD. Hardness, and density of these composites were also measured. The microstructure and mechanical properties tests of composites and study the effect of particle size, resulted the better properties compared to matrix aluminum. Homogeneous dispersion of the reinforcement particles in the matrix aluminum was observed. The results show enhancing the composites properties for all samples compared to the monolithic alloy. However there are some differences in results because of particle size of ceramics and therefore differences between particles surface area. Maximum volume percent that can be added to A356 aluminum alloy is 5 vol.%, for nano ZrO II particles, but it seems that is more than 5 vol.% for micron particles. Increasing of viscosity, porosities and much more defects are caused by increasing volume percents and using smaller particles. The casting processing is difficult in these conditions. Furthermore, optimum temperatures of casting for micron and nano zirconia particles are not the same.

  17. Radiation chemistry of heavy-particle tracks. II. Fricke dosimeter system

    SciTech Connect

    Chatterjee, A.; Magee, J.L.

    1980-12-25

    A heavy-particle-track model suggested by considerations presented in a companion paper is used in a calculation of the differential (G') and integral (G) yields of the Fricke dosimeter system for six selected particles over a wide range of energies. The particles are H, He, C, Ne, Ar, and Fm; the energy range for the first two is 10/sup -3/-10/sup 3/ MeV/n, and for the last four is 10/sup -1/-10/sup 3/ MeV/n. The calculated G' and G values are compared with experimental values as far as possible, and the heavy-particle-track model situation is discussed.

  18. Direct energy transfer from the major antenna to the photosystem II core complexes in the absence of minor antennae in liposomes.

    PubMed

    Sun, Ruixue; Liu, Kun; Dong, Lianqing; Wu, Yuling; Paulsen, Harald; Yang, Chunhong

    2015-02-01

    Minor antennae of photosystem (PS) II, located between the PSII core complex and the major antenna (LHCII), are important components for the structural and functional integrity of PSII supercomplexes. In order to study the functional significance of minor antennae in the energetic coupling between LHCII and the PSII core, characteristics of PSII-LHCII proteoliposomes, with or without minor antennae, were investigated. Two types of PSII preparations containing different antenna compositions were isolated from pea: 1) the PSII preparation composed of the PSII core complex, all of the minor antennae, and a small amount of major antennae (MCC); and 2) the purified PSII dimeric core complexes without periphery antenna (CC). They were incorporated, together with LHCII, into liposomes composed of thylakoid membrane lipids. The spectroscopic and functional characteristics were measured. 77K fluorescence emission spectra revealed an increased spectral weight of fluorescence from PSII reaction center in the CC-LHCII proteoliposomes, implying energetic coupling between LHCII and CC in the proteoliposomes lacking minor antennae. This result was further confirmed by chlorophyll a fluorescence induction kinetics. The incorporation of LHCII together with CC markedly increased the antenna cross-section of the PSII core complex. The 2,6-dichlorophenolindophenol photoreduction measurement implied that the lack of minor antennae in PSII supercomplexes did not block the energy transfer from LHCII to the PSII core complex. In conclusion, it is possible, in liposomes, that LHCII transfer energy directly to the PSII core complex, in the absence of minor antennae.

  19. Physicochemical characterization of Capstone depleted uranium aerosols II: particle size distributions as a function of time.

    PubMed

    Cheng, Yung Sung; Kenoyer, Judson L; Guilmette, Raymond A; Parkhurst, Mary Ann

    2009-03-01

    The Capstone Depleted Uranium (DU) Aerosol Study, which generated and characterized aerosols containing DU from perforation of armored vehicles with large-caliber DU penetrators, incorporated a sampling protocol to evaluate particle size distributions. Aerosol particle size distribution is an important parameter that influences aerosol transport and deposition processes as well as the dosimetry of the inhaled particles. These aerosols were collected on cascade impactor substrates using a pre-established time sequence following the firing event to analyze the uranium concentration and particle size of the aerosols as a function of time. The impactor substrates were analyzed using proportional counting, and the derived uranium content of each served as input to the evaluation of particle size distributions. Activity median aerodynamic diameters (AMADs) of the particle size distributions were evaluated using unimodal and bimodal models. The particle size data from the impactor measurements were quite variable. Most size distributions measured in the test based on activity had bimodal size distributions with a small particle size mode in the range of between 0.2 and 1.2 microm and a large size mode between 2 and 15 microm. In general, the evolution of particle size over time showed an overall decrease of average particle size from AMADs of 5 to 10 microm shortly after perforation to around 1 microm at the end of the 2-h sampling period. The AMADs generally decreased over time because of settling. Additionally, the median diameter of the larger size mode decreased with time. These results were used to estimate the dosimetry of inhaled DU particles.

  20. Physicochemical Characterization of Capstone Depleted Uranium Aerosols II: Particle Size Distributions as a Function of Time

    SciTech Connect

    Cheng, Yung-Sung; Kenoyer, Judson L.; Guilmette, Raymond A.; Parkhurst, MaryAnn

    2009-03-01

    The Capstone Depleted Uranium (DU) Aerosol Study, which generated and characterized aerosols containing depleted uranium from perforation of armored vehicles with large-caliber DU penetrators, incorporated a sampling protocol to evaluated particle size distributions. Aerosol particle size distribution is an important parameter that influences aerosol transport and deposition processes as well as the dosimetry of the inhaled particles. These aerosols were collected on cascade impactor substrates using a pre-established time sequence following the firing event to analyze the uranium concentration and particle size of the aerosols as a function of time. The impactor substrates were analyzed using beta spectrometry, and the derived uranium content of each served as input to the evaluation of particle size distributions. Activity median aerodynamic diameters (AMADs) of the particle size distributions were evaluated using unimodal and bimodal models. The particle size data from the impactor measurements was quite variable. Most size distributions measured in the test based on activity had bimodal size distributions with a small particle size mode in the range of between 0.2 and 1.2 um and a large size mode between 2 and 15 um. In general, the evolution of particle size over time showed an overall decrease of average particle size from AMADs of 5 to 10 um shortly after perforation to around 1 um at the end of the 2-hr sampling period. The AMADs generally decreased over time because of settling. Additionally, the median diameter of the larger size mode decreased with time. These results were used to estimate the dosimetry of inhaled DU particles.

  1. The construction, characterization, Hg(II)-sensing and removal behavior of magnetic core-shell nanospheres loaded with fluorescence "Off-On" probe.

    PubMed

    Tan, Jun; Wei, Xiaoyan; Chen, Jie; Sun, Ping; Ouyang, Yuxia; Fan, Juhong; Liu, Rui

    2014-12-10

    The present paper constructed and discussed core-shell structured nanospheres grafted with rhodamine based probe for Hg(II) sensing and removal. Electron microscopy images, XRD curves, thermogravimetric analysis and N2 adsorption/desorption isotherms were used to identify the core-shell structure. The inner core consisted of superparamagnetic Fe3O4 nanoparticles, which made the nanocomposite magnetically removable. The outer shell was constructed with silica molecular sieve which provided large surface area and ordered tunnels for the sensing probe, accelerating analyte adsorption and transportation. The rhodamine based sensing probe emission increased with the increasing Hg(II) concentration, showing emission "Off-On" effect, which could be explained by the structural transformation from a non-emissive one to a highly emissive one. The influence from various metal ions and pH values was also investigated, which suggested this structural transformation could only be triggered by Hg(II), showing high selectivity and linear response. The Hg(II) sensing nanocomposite could be regenerated after usage. The response time was slightly compromised and could be further improved.

  2. Preparation of a core-shell magnetic ion-imprinted polymer via a sol-gel process for selective extraction of Cu(II) from herbal medicines.

    PubMed

    He, Huan; Xiao, Deli; He, Jia; Li, Hui; He, Hua; Dai, Hao; Peng, Jun

    2014-05-21

    A novel magnetic surface ion-imprinted polymer (c-MMWCNTs-SiO2-IIP) was synthesized for the first time using magnetic CNTs/Fe3O4 composites (c-MMWCNTs) as the core, 3-ammonium propyltriethoxysilane (APTES) as the functional monomer, tetraethylorthosilicate (TEOS) as the cross-linker and Cu(II) as the template. c-MMWCNTs-SiO2-IIP was evaluated for selective extraction of Cu(II) from herbal medicines via a magnetic solid phase extraction (M-SPE) procedure. One factor affecting the separation and preconcentration of the target heavy metal was pH. Under the optimized experimental conditions, the adsorption kinetics and adsorption capacity of c-MMWCNTs-SiO2-IIP toward Cu(II) were estimated. The results indicated that the adsorption mechanism corresponds to a pseudo-second order adsorption process, with a correlation coefficient (R(2)) of 0.985 and a maximum adsorption capacity of 42.2 mg g(-1). The relative selectivity factor (β) values of Cu(II)/Zn(II) and Cu(II)/Pb(II) were 38.5 and 34.5, respectively. c-MMWCNTs-SiO2-IIP, combined with flame atomic absorption spectrometry, was successfully applied in the extraction and detection of Cu(II) in herbal medicine, with high recoveries ranging from 95.6% to 108.4%.

  3. Detection and tracking of dual-labeled HIV particles using wide-field live cell imaging to follow viral core integrity

    PubMed Central

    Mamede, Joao I.; Hope, Thomas J.

    2016-01-01

    Summary Live cell imaging is a valuable technique that allows the characterization of the dynamic processes of the HIV-1 life-cycle. Here, we present a method of production and imaging of dual-labeled HIV viral particles that allows the visualization of two events. Varying release of the intravirion fluid phase marker reveals virion fusion and the loss of the integrity of HIV viral cores with the use of live wide-field fluorescent microscopy. PMID:26714704

  4. An assessment of Southern Ocean water masses and sea ice during 1988-2007 in a suite of interannual CORE-II simulations

    NASA Astrophysics Data System (ADS)

    Downes, Stephanie M.; Farneti, Riccardo; Uotila, Petteri; Griffies, Stephen M.; Marsland, Simon J.; Bailey, David; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Böning, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Chassignet, Eric; Danabasoglu, Gokhan; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Fogli, Pier Giuseppe; Gusev, Anatoly; Howard, Armando; Ilicak, Mehmet; Jung, Thomas; Kelley, Maxwell; Large, William G.; Leboissetier, Anthony; Long, Matthew; Lu, Jianhua; Masina, Simona; Mishra, Akhilesh; Navarra, Antonio; George Nurser, A. J.; Patara, Lavinia; Samuels, Bonita L.; Sidorenko, Dmitry; Spence, Paul; Tsujino, Hiroyuki; Wang, Qiang; Yeager, Stephen G.

    2015-10-01

    We characterise the representation of the Southern Ocean water mass structure and sea ice within a suite of 15 global ocean-ice models run with the Coordinated Ocean-ice Reference Experiment Phase II (CORE-II) protocol. The main focus is the representation of the present (1988-2007) mode and intermediate waters, thus framing an analysis of winter and summer mixed layer depths; temperature, salinity, and potential vorticity structure; and temporal variability of sea ice distributions. We also consider the interannual variability over the same 20 year period. Comparisons are made between models as well as to observation-based analyses where available. The CORE-II models exhibit several biases relative to Southern Ocean observations, including an underestimation of the model mean mixed layer depths of mode and intermediate water masses in March (associated with greater ocean surface heat gain), and an overestimation in September (associated with greater high latitude ocean heat loss and a more northward winter sea-ice extent). In addition, the models have cold and fresh/warm and salty water column biases centred near 50°S. Over the 1988-2007 period, the CORE-II models consistently simulate spatially variable trends in sea-ice concentration, surface freshwater fluxes, mixed layer depths, and 200-700 m ocean heat content. In particular, sea-ice coverage around most of the Antarctic continental shelf is reduced, leading to a cooling and freshening of the near surface waters. The shoaling of the mixed layer is associated with increased surface buoyancy gain, except in the Pacific where sea ice is also influential. The models are in disagreement, despite the common CORE-II atmospheric state, in their spatial pattern of the 20-year trends in the mixed layer depth and sea-ice.

  5. An Assessment of Southern Ocean Water Masses and Sea Ice During 1988-2007 in a Suite of Interannual CORE-II Simulations

    NASA Technical Reports Server (NTRS)

    Downes, Stephanie M.; Farneti, Riccardo; Uotila, Petteri; Griffies, Stephen M.; Marsland, Simon J.; Bailey, David; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Canuto, Vittorio M.; Howard, Armando; Kelley, Maxwell; Leboissetier, Anthony

    2015-01-01

    We characterise the representation of the Southern Ocean water mass structure and sea ice within a suite of 15 global ocean-ice models run with the Coordinated Ocean-ice Reference Experiment Phase II (CORE-II) protocol. The main focus is the representation of the present (1988-2007) mode and intermediate waters, thus framing an analysis of winter and summer mixed layer depths; temperature, salinity, and potential vorticity structure; and temporal variability of sea ice distributions. We also consider the interannual variability over the same 20 year period. Comparisons are made between models as well as to observation-based analyses where available. The CORE-II models exhibit several biases relative to Southern Ocean observations, including an underestimation of the model mean mixed layer depths of mode and intermediate water masses in March (associated with greater ocean surface heat gain), and an overestimation in September (associated with greater high latitude ocean heat loss and a more northward winter sea-ice extent). In addition, the models have cold and fresh/warm and salty water column biases centred near 50 deg S. Over the 1988-2007 period, the CORE-II models consistently simulate spatially variable trends in sea-ice concentration, surface freshwater fluxes, mixed layer depths, and 200-700 m ocean heat content. In particular, sea-ice coverage around most of the Antarctic continental shelf is reduced, leading to a cooling and freshening of the near surface waters. The shoaling of the mixed layer is associated with increased surface buoyancy gain, except in the Pacific where sea ice is also influential. The models are in disagreement, despite the common CORE-II atmospheric state, in their spatial pattern of the 20-year trends in the mixed layer depth and sea-ice.

  6. Effective removal of Ni(II) from aqueous solutions by modification of nano particles of clinoptilolite with dimethylglyoxime.

    PubMed

    Nezamzadeh-Ejhieh, Alireza; Kabiri-Samani, Mehdi

    2013-09-15

    In this work an Iranian natural clinoptilolite tuff was pre-treated and changed to the micro (MCP) and nano (NCP) particles by mechanical method. Modification of micro and nano particles and also their Ni-exchanged forms were done by dimethylglyoxime (DMG). The raw and modified samples were characterized by XRD, FT-IR, SEM, BET, TG-DTG and energy dispersive analysis X-ray spectroscopy (EDAX). Removal of Ni(II) by modified and unmodified samples was investigated in batch procedure. It was found that NCP-DMG has higher capacity for removal of Ni(II). The effects of analytical parameters such as pH, dose of DMG, concentration of nickel solution, contact time and selectivity were studied and the optimal operation parameters were found as follows: pHPZC: 7.6, CNi(II): 0.01 M, contact time: 360 min and DMG dosage: 5mM. The results of selectivity experiments showed that the modified zeolite has a good selectivity for nickel in the presence of different multivalent cations. Langmuir and Freundlich isotherm models were adopted to describe the adsorption isotherms. Adsorption isotherms of Ni(II) ions could be best modelled by Langmuir equation, that indicate the monolayer sorption of Ni(II). Comparison of two kinetic models indicates that the adsorption kinetic can be well described by the pseudo-second-order rate equation that indicates that the rate limiting step for the process involves chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneously process. The negative ΔS indicates that the adsorption of nickel cations from solution occurs with lower amount ion replacement, thus chemisorptions due to complex formation are dominant process in nickel removal.

  7. In vitro recognition of DNA base pairs by histones in histone-DNA complexes and reconstituted core particles: an ultraviolet resonance Raman study.

    PubMed Central

    Laigle, A; Chinsky, L; Turpin, P Y; Liquier, J; Taillandier, E

    1982-01-01

    Resonance Raman spectra of complexes between DNA and the four core histones, alone or associated, have been investigated in vitro using excitations at 300 and 257 nm, which give complementary informations about the DNA bases. H2A and H2B fractions recognize the G-C base pairs, while H3 and H4 (arginine rich fractions) recognize the A-T base pairs. The associated fractions form complexes with DNA which yield about the same DNA spectral modifications as the DNA-H4 complexes. This reveals the important role of the arginine rich fractions in the core particle formation and confirms the preferential in vitro assembly of nucleosome cores on A-T rich regions of DNA (25). PMID:7155896

  8. Investigation of a new core-shell particle column for ion-pair reversed-phase liquid chromatography analysis of oligonucleotides.

    PubMed

    Biba, Mirlinda; Welch, Christopher J; Foley, Joe P

    2014-08-05

    A new core-shell particle column showed excellent performance and durability for separation of short (∼21-mer) ribonucleic acid (RNA) oligonucleotides by ion-pair reversed-phase liquid chromatography (IP-RPLC). Previously investigated core-shell C18 columns showed excellent peak shapes and separations of closely eluting impurities by IP-RPLC. However, these columns showed only modest long-term stability at the neutral pH and elevated column temperatures of ≥60°C, typically used for IP-RPLC analysis of oligonucleotides. The newly introduced SunShell C18 column provided separations comparable to the previously evaluated core-shell columns, but with significantly improved long-term column stability when operated at neutral pH and elevated column temperature.

  9. Core-shell monodisperse spherical mSiO2/Gd2O3:Eu3+@mSiO2 particles as potential multifunctional theranostic agents

    NASA Astrophysics Data System (ADS)

    Eurov, Daniil A.; Kurdyukov, Dmitry A.; Kirilenko, Demid A.; Kukushkina, Julia A.; Nashchekin, Alexei V.; Smirnov, Alexander N.; Golubev, Valery G.

    2015-02-01

    Core-shell nanoparticles with diameters in the range 100-500 nm have been synthesized as monodisperse spherical mesoporous (pore diameter 3 nm) silica particles with size deviation of less than 4 %, filled with gadolinium and europium oxides and coated with a mesoporous silica shell. It is shown that the melt technique developed for filling with gadolinium and europium oxides provides a nearly maximum filling of mesopores in a single-run impregnation, with gadolinium and europium uniformly distributed within the particles and forming no bulk oxides on their surface. The coating with a shell does not impair the monodispersity and causes no coagulation. The coating technique enables controlled variation of the shell thickness within the range 5-100 % relative to the core diameter. The thus produced nanoparticles are easily dispersed in water, have large specific surface area (300 m2 g-1) and pore volume (0.3 cm3 g-1), and are bright solid phosphor with superior stability in aqueous media. The core-shell structured particles can be potentially used for cancer treatment as a therapeutic agent (gadolinium neutron-capture therapy and drug delivery system) and, simultaneously, as a multimodal diagnostic tool (fluorescence and magnetic resonance imaging), thereby serving as a multifunctional theranostic agent.

  10. Core-shell magnetite-silica dithiocarbamate-derivatised particles achieve the Water Framework Directive quality criteria for mercury in surface waters.

    PubMed

    Lopes, C B; Figueira, P; Tavares, D S; Lin, Z; Daniel-da-Silva, A L; Duarte, A C; Rocha, J; Trindade, T; Pereira, E

    2013-09-01

    The sorption capacity of nanoporous titanosilicate Engelhard titanosilicate number 4 (ETS-4) and silica-coated magnetite particles derivatised with dithiocarbamate groups towards Hg(II) was evaluated and compared in spiked ultra-pure and spiked surface-river water, for different batch factors. In the former, and using a batch factor of 100 m(3)/kg and an initial Hg(II) concentrations matching the maximum allowed concentration in an effluent discharge, both materials achieve Hg(II) uptake efficiencies in excess of 99 % and a residual metal concentration lower than the guideline value for drinking water quality. For the surface-river water and the same initial concentration, the Hg(II) uptake efficiency of magnetite particles is outstanding, achieving the quality criteria established by the Water Framework Directive (concerning Hg concentration in surface waters) using a batch factor of 50 m(3)/kg, while the efficiency of ETS-4 is significantly inferior. The dissimilar sorbents' Hg(II) removal efficiency is attributed to different uptake mechanisms. This study also highlights the importance of assessing the effective capacity of the sorbents under realistic conditions in order to achieve trustable results.

  11. Validation of updated neutronic calculation models proposed for Atucha-II PHWR. Part II: Benchmark comparisons of PUMA core parameters with MCNP5 and improvements due to a simple cell heterogeneity correction

    SciTech Connect

    Grant, C.; Mollerach, R.; Leszczynski, F.; Serra, O.; Marconi, J.; Fink, J.

    2006-07-01

    In 2005 the Argentine Government took the decision to complete the construction of the Atucha-II nuclear power plant, which has been progressing slowly during the last ten years. Atucha-II is a 745 MWe nuclear station moderated and cooled with heavy water, of German (Siemens) design located in Argentina. It has a pressure vessel design with 451 vertical coolant channels and the fuel assemblies (FA) are clusters of 37 natural UO{sub 2} rods with an active length of 530 cm. For the reactor physics area, a revision and update of reactor physics calculation methods and models was recently carried out covering cell, supercell (control rod) and core calculations. This paper presents benchmark comparisons of core parameters of a slightly idealized model of the Atucha-I core obtained with the PUMA reactor code with MCNP5. The Atucha-I core was selected because it is smaller, similar from a neutronic point of view, more symmetric than Atucha-II, and has some experimental data available. To validate the new models benchmark comparisons of k-effective, channel power and axial power distributions obtained with PUMA and MCNP5 have been performed. In addition, a simple cell heterogeneity correction recently introduced in PUMA is presented, which improves significantly the agreement of calculated channel powers with MCNP5. To complete the validation, the calculation of some of the critical configurations of the Atucha-I reactor measured during the experiments performed at first criticality is also presented. (authors)

  12. The dynamics of particle disks. II - Effects of spin degrees of freedom

    NASA Technical Reports Server (NTRS)

    Araki, Suguru

    1988-01-01

    The present treatment of the thermal equilibria of differentially-rotating, axisymmetric disks consisting of identical, spin-possessing as well as translational DOF-possessing hard sphere particles characterizes these disks' dynamics by means of two novel parameters: (1) the tangential restitution coefficient, and (2) the dimensionless moment of inertia. It is established that rings composed of spinning particles can generally be thermally balanced within more restricted ranges of the optical depth, as well as at higher values of the normal restitution coefficient, than spinless rings. Mean spin is indefinite in the present framework of neglected finite particle-size effects.

  13. Low power loss and field-insensitive permeability of Fe-6.5%Si powder cores with manganese oxide-coated particles

    SciTech Connect

    Li, Junnan E-mail: rzhgong@hust.edu.cn; Wang, Xian; Xu, Xiaojun; Gong, Rongzhou E-mail: rzhgong@hust.edu.cn; Feng, Zekun; Chen, Yajie; Harris, V. G.

    2015-05-07

    Fe-6.5%Si alloy powders coated with manganese oxides using an innovative in situ process were investigated. The in-situ coating of the insulating oxides was realized with a KMnO{sub 4} solution by a chemical process. The insulating manganese oxides with mixed valance state were verified by X-ray photoelectron spectroscopy analysis. The thickness of the insulating layer on alloy particles was determined to be in a range of 20–210 nm, depending upon the KMnO{sub 4} concentration. The powder core loss and the change in permeability under a DC-bias field were measured at frequencies ranging from 50 to 100 kHz. The experiments indicated that the Fe-6.5%Si powder cores with a 210 nm-thick manganese oxide layer not only showed a low core loss of 459 mW/cm{sup 3} at 100 kHz but also showed a small reduction in permeability (μ(H)/μ(0) = 85% for μ = 42) at a DC-bias field of 80 Oe. This work has defined a novel pathway to realizing low core loss and field-insensitive permeability for Fe-Si powder cores.

  14. Construction and immunological evaluation of truncated hepatitis B core particles carrying HBsAg amino acids 119-152 in the major immunodominant region (MIR).

    PubMed

    Su, Qiudong; Yi, Yao; Guo, Minzhuo; Qiu, Feng; Jia, Zhiyuan; Lu, Xuexin; Meng, Qingling; Bi, Shengli

    2013-09-13

    Hepatitis B capsid protein expressed in Escherichia coli can reassemble into icosahedral particles, which could strongly enhance the immunogenicity of foreign epitopes, especially those inserted into its major immunodominant region. Herein, we inserted the entire 'α' antigenic determinant amino acids (aa) 119-152 of HBsAg into the truncated HBc (aa 1-144), between Asp(78) and Pro(79). Prokaryotic expression showed that the mosaic HBc was mainly in the form of inclusion bodies. After denaturation with urea, it was dialyzed progressively for protein renaturation. We observed that before and after renaturation, mosaic HBc was antigenic as determined by HBsAg ELISA and a lot of viruslike particles were observed after renaturation. Thus, we further purified the mosaic viruslike particles by (NH4)2SO4 precipitation, DEAE chromatography, and Sepharose 4FF chromatography. Negative staining electron microscopy demonstrated the morphology of the viruslike particles. Immunization of Balb/c mice with mosaic particles induced the production of anti-HBs antibody and Th1 cell immune response supported by ELISPOT and CD4/CD8 proportions assay. In conclusion, we constructed mosaic hepatitis core particles displaying the entire 'α' antigenic determinant on the surface and laid a foundation for researching therapeutic hepatits B vaccines.

  15. Energy spectrum of an exciton in a CdSe/ZnTe type-II core/shell spherical quantum dot

    NASA Astrophysics Data System (ADS)

    Chafai, A.; Dujardin, F.; Essaoudi, I.; Ainane, A.

    2017-01-01

    The binding energy of an exciton inside a CdSe/ZnTe core/shell spherical quantum dot was theoretically examined taking into account the dependence of the dielectric constant and charge carriers effective mass on radius, and using the envelope function approximation. Such a structure presents original optical and electronic properties because of the spatial separation of electrons and holes caused by the type-II alignment of energy states. The mean distance between the electron and hole was calculated variationally using a trial function taking into account the coulomb interaction between charge carriers. Our numerical results provide a description to the size dependence of the binding energy of an exciton inside a core/shell nanoheterostructure type-II. Indeed, by controlling the inner and outer radii, we can precisely control the energy spectrum of the exciton.

  16. Turbulence-induced relative velocity of dust particles. II. The bidisperse case

    SciTech Connect

    Pan, Liubin; Padoan, Paolo; Scalo, John E-mail: ppadoan@icc.ub.edu

    2014-08-10

    We extend our earlier work on turbulence-induced relative velocity between equal-size particles (Paper I, in this series) to particles of arbitrarily different sizes. The Pan and Padoan (PP10) model shows that the relative velocity between different particles has two contributions, named the generalized shear and acceleration terms, respectively. The generalized shear term represents the particles' memory of the spatial flow velocity difference across the particle distance in the past, while the acceleration term is associated with the temporal flow velocity difference on individual particle trajectories. Using the simulation of Paper I, we compute the root-mean-square relative velocity, (w {sup 2}){sup 1/2}, as a function of the friction times, τ{sub p1} and τ{sub p2}, of the two particles and show that the PP10 prediction is in satisfactory agreement with the data, confirming its physical picture. For a given τ{sub p1} below the Lagrangian correlation time of the flow, T{sub L}, (w {sup 2}){sup 1/2} as a function of τ{sub p2} shows a dip at τ{sub p2} ≅ τ{sub p1}, indicating tighter velocity correlation between similar particles. Defining a ratio f ≡ τ{sub p,{sub l}}/τ{sub p,{sub h}}, with τ{sub p,{sub l}} and τ{sub p,{sub h}} the friction times of the smaller and larger particles, we find that (w {sup 2}){sup 1/2} increases with decreasing f due to the generalized acceleration contribution, which dominates at f ≲ 1/4. At a fixed f, our model predicts that (w {sup 2}){sup 1/2} scales as τ{sub p,h}{sup 1/2} for τ{sub p,{sub h}} in the inertial range of the flow, stays roughly constant for T{sub L} ≲ τ{sub p,{sub h}} ≲ T{sub L}/f, and finally decreases as τ{sub p,h}{sup −1/2} for τ{sub p,{sub h}} >> T{sub L}/f. The acceleration term is independent of the particle distance, r, and reduces the r dependence of (w {sup 2}){sup 1/2} in the bidisperse case.

  17. Charge neutralization as the major factor for the assembly of nucleocapsid-like particles from C-terminal truncated hepatitis C virus core protein

    PubMed Central

    Braga, Vanessa L. de Azevedo; Peabody, David S.; Ferreira, Davis Fernandes; Bianconi, M. Lucia; Gomes, Andre Marco de Oliveira

    2016-01-01

    Background Hepatitis C virus (HCV) core protein, in addition to its structural role to form the nucleocapsid assembly, plays a critical role in HCV pathogenesis by interfering in several cellular processes, including microRNA and mRNA homeostasis. The C-terminal truncated HCV core protein (C124) is intrinsically unstructured in solution and is able to interact with unspecific nucleic acids, in the micromolar range, and to assemble into nucleocapsid-like particles (NLPs) in vitro. The specificity and propensity of C124 to the assembly and its implications on HCV pathogenesis are not well understood. Methods Spectroscopic techniques, transmission electron microscopy and calorimetry were used to better understand the propensity of C124 to fold or to multimerize into NLPs when subjected to different conditions or in the presence of unspecific nucleic acids of equivalent size to cellular microRNAs. Results The structural analysis indicated that C124 has low propensity to self-folding. On the other hand, for the first time, we show that C124, in the absence of nucleic acids, multimerizes into empty NLPs when subjected to a pH close to its isoelectric point (pH ≈ 12), indicating that assembly is mainly driven by charge neutralization. Isothermal calorimetry data showed that the assembly of NLPs promoted by nucleic acids is enthalpy driven. Additionally, data obtained from fluorescence correlation spectroscopy show that C124, in nanomolar range, was able to interact and to sequester a large number of short unspecific nucleic acids into NLPs. Discussion Together, our data showed that the charge neutralization is the major factor for the nucleocapsid-like particles assembly from C-terminal truncated HCV core protein. This finding suggests that HCV core protein may physically interact with unspecific cellular polyanions, which may correspond to microRNAs and mRNAs in a host cell infected by HCV, triggering their confinement into infectious particles. PMID:27867765

  18. A review of biomass burning emissions part II: intensive physical properties of biomass burning particles

    NASA Astrophysics Data System (ADS)

    Reid, J. S.; Koppmann, R.; Eck, T. F.; Eleuterio, D. P.

    2005-03-01

    The last decade has seen tremendous advances in atmospheric aerosol particle research that is often performed in the context of climate and global change science. Biomass burning, one of the largest sources of accumulation mode particles globally, has been closely studied for its radiative, geochemical, and dynamic impacts. These studies have taken many forms including laboratory burns, in situ experiments, remote sensing, and modeling. While the differing perspectives of these studies have ultimately improved our qualitative understanding of biomass-burning issues, the varied nature of the work make inter-comparisons and resolutions of some specific issues difficult. In short, the literature base has become a milieu of small pieces of the biomass-burning puzzle. This manuscript, the second part of four, examines the properties of biomass-burning particle emissions. Here we review and discuss the literature concerning the measurement of smoke particle size, chemistry, thermodynamic properties, and emission factors. Where appropriate, critiques of measurement techniques are presented. We show that very large differences in measured particle properties have appeared in the literature, in particular with regards to particle carbon budgets. We investigate emissions uncertainties using scale analyses, which shows that while emission factors for grass and brush are relatively well known, very large uncertainties still exist in emission factors of boreal, temperate and some tropical forests. Based on an uncertainty analysis of the community data set of biomass burning measurements, we present simplified models for particle size and emission factors. We close this review paper with a discussion of the community experimental data, point to lapses in the data set, and prioritize future research topics.

  19. A review of biomass burning emissions, part II: Intensive physical properties of biomass burning particles

    NASA Astrophysics Data System (ADS)

    Reid, J. S.; Koppmann, R.; Eck, T. F.; Eleuterio, D. P.

    2004-09-01

    The last decade has seen tremendous advances in atmospheric aerosol particle research that is often performed in the context of climate and global change science. Biomass burning, one of the largest sources of accumulation mode particles globally, has been closely studied for its radiative, geochemical, and dynamic impacts. These studies have taken many forms including laboratory burns, in situ experiments, remote sensing, and modeling. While the differing perspectives of these studies have ultimately improved our qualitative understanding of biomass burning issues, the varied nature of the work make inter-comparisons and resolutions of some specific issues difficult. In short, the literature base has become a milieu of small pieces of the biomass-burning puzzle. This manuscript, the second part of four, examines the properties of biomass-burning particle emissions. Here we review and discuss the literature concerning the measurement of smoke particle size, chemistry, thermodynamic properties, and emission factors. Where appropriate, critiques of measurement techniques are presented. We show that very large differences in measured particle properties have appeared in the literature, in particular with regards to particle carbon budgets. We investigate emissions uncertainties using scale analyses, which shows that while emission factors for grass and brush are relatively well known, very large uncertainties still exist in emission factors of boreal, temperate and some tropical forests. Based on an uncertainty analysis of the community data set of biomass burning measurements, we present simplified models for particle size and emission factors. We close this review paper with a discussion of the community experimental data, point to lapses in the data set, and prioritize future research topics.

  20. New core@shell nanogel based 2-acrylamido-2-methyl-1-propane sulfonic acid for preconcentration of Pb(II) from various water samples

    NASA Astrophysics Data System (ADS)

    Shoueir, Kamel Rizq; Akl, Magda Ali; Sarhan, Ali Ali; Atta, Ayman Mohamdy

    2016-12-01

    Poly(vinyl alcohol) core coated with poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-N-isopropylacrylamide) shell to produce well-define PVA@P(AMPS-co-NIPAm) core shell nanogels with a core of 25 ± 0.5 nm and shell of 5 ± 0.5 nm. The synthetic approach was produced by a surfactant free emulsion polymerization (SFEP). The specific area was found to be 1685.8 m2/g. The nanogels were studied in a batch adsorption for removal of Pb(II) ions and characterized by SEM, TEM, TGA and BET measurements. The results showed that the adsorption equilibrium data fitted the Langmuir isotherm and the kinetic studies are well described by the pseudo-second-order kinetic model. The Pb(II) maximum adsorption was 510.2 (mg/g) for PVA@P(90AMPS-co-10NIPAm) (wt.: wt%). The PVA@P(AMPS-co-NIPAm) nanogels were applied for extracting of Pb(II) in real different environmental water samples successfully with high recoveries reaches 104.4%.

  1. On the question of the light-harvesting role of β-carotene in photosystem II and photosystem I core complexes.

    PubMed

    Stamatakis, Kostas; Tsimilli-Michael, Merope; Papageorgiou, George C

    2014-08-01

    β-Carotene is the only carotenoid present in the core complexes of Photosystems I and II. Its proximity to chlorophyll a molecules enables intermolecular electronic interactions, including β-carotene to chlorophyll a electronic excitation transfers. However, it has been well documented that, compared to chlorophylls and to phycobilins, the light harvesting efficiency of β-carotenes for photosynthetic O2 evolution is poor. This is more evident in cyanobacteria than in plants and algae because they lack accessory light harvesting pigments with absorptions that overlap the β-carotene absorption. In the present work we investigated the light harvesting role of β-carotenes in the cyanobacterium Synechococcus sp. PCC 7942 using selective β-carotene excitation and selective Photosystem detection of photo-induced electron transport to and from the intersystem plastoquinones (the plastoquinone pool). We report that, although selectively excited β-carotenes transfer electronic excitation to the chlorophyll a of both photosystems, they enable only the oxidation of the plastoquinone pool by Photosystem I but not its reduction by Photosystem II. This may suggest a light harvesting role for the β-carotenes of the Photosystem I core complex but not for those of the Photosystem II core complex. According to the present investigation, performed with whole cyanobacterial cells, the lower photosynthesis yields measured with β-Car-absorbed light can be attributed to the different excitation trapping efficiencies in the reaction centers of PSI and PSII.

  2. Dissolution of particles in binary alloys: part II. experimental investigation on an Al-Si alloy

    NASA Astrophysics Data System (ADS)

    Tundal, Ulf H.; Ryum, Nils

    1992-02-01

    A detailed experimental study of the dissolution kinetics of Si particles in an Al-Si alloy has been carried out in order to test the validity of the two models presented in the accompanying article.[1] In these models, the dissolution kinetics are dependent on the particle size distribution of the alloy. An alloy with composition Co = 0.77 at. pct Si was heat-treated in order to obtain rather coarse spherical particles (1 to 10 μn). The size distribution of the particles was found to be close to the log-normal distribution. At high temperatures, when the solvus concentration was well above Co, the experimental values were very close to the values of the model which predicted the highest dissolution rates. At lower temperatures, when the solvus concentration was closer to C o, the experimental values lay in between the values predicted by the two models. The results clearly demonstrate that a size distribution of particles must be included in the model if an accurate prediction of the dissolution kinetics is to be achieved.

  3. Multi-responsive hybrid particles: thermo-, pH-, photo-, and magneto-responsive magnetic hydrogel cores with gold nanorod optical triggers

    NASA Astrophysics Data System (ADS)

    Rittikulsittichai, Supparesk; Kolhatkar, Arati G.; Sarangi, Subhasis; Vorontsova, Maria A.; Vekilov, Peter G.; Brazdeikis, Audrius; Randall Lee, T.

    2016-06-01

    The research strategy described in this manuscript harnesses the attractive properties of hydrogels, gold nanorods (Aurods), and magnetic nanoparticles (MNPs) by synthesizing one unique multi-responsive nanostructure. This novel hybrid structure consists of silica-coated magnetic particles encapsulated within a thermo-responsive P(NIPAM-co-AA) hydrogel network on which Aurods are assembled. Furthermore, this research demonstrates that these composite particles respond to several forms of external stimuli (temperature, pH, light, and/or applied magnetic field) owing to their specific architecture. Exposure of the hybrid particles to external stimuli led to a systematic and reversible variation in the hydrodynamic diameter (swelling-deswelling) and thus in the optical properties of the hybrid particles (red-shifting of the plasmon band). Such stimuli-responsive volume changes can be effectively exploited in drug-delivery applications.The research strategy described in this manuscript harnesses the attractive properties of hydrogels, gold nanorods (Aurods), and magnetic nanoparticles (MNPs) by synthesizing one unique multi-responsive nanostructure. This novel hybrid structure consists of silica-coated magnetic particles encapsulated within a thermo-responsive P(NIPAM-co-AA) hydrogel network on which Aurods are assembled. Furthermore, this research demonstrates that these composite particles respond to several forms of external stimuli (temperature, pH, light, and/or applied magnetic field) owing to their specific architecture. Exposure of the hybrid particles to external stimuli led to a systematic and reversible variation in the hydrodynamic diameter (swelling-deswelling) and thus in the optical properties of the hybrid particles (red-shifting of the plasmon band). Such stimuli-responsive volume changes can be effectively exploited in drug-delivery applications. Electronic supplementary information (ESI) available: Contains detailed information about the synthesis of

  4. Construction and immunological evaluation of truncated hepatitis B core particles carrying HBsAg amino acids 119–152 in the major immunodominant region (MIR)

    SciTech Connect

    Su, Qiudong; Yi, Yao; Guo, Minzhuo; Qiu, Feng; Jia, Zhiyuan; Lu, Xuexin; Meng, Qingling; Bi, Shengli

    2013-09-13

    Highlights: •The conformational HBV neutralization antigen domain was successfully displayed on the surface of truncated HBc particles. •Appropriate dialysis procedures to support the renaturing environment for the protein refolding. •Efficient purification procedures to obtain high purity and icosahedral particles of mosaic HBV antigen. •Strong immune responses not only including neutralization antibody response but also Th1 cell response were induced in mice. -- Abstract: Hepatitis B capsid protein expressed in Escherichia coli can reassemble into icosahedral particles, which could strongly enhance the immunogenicity of foreign epitopes, especially those inserted into its major immunodominant region. Herein, we inserted the entire ‘α’ antigenic determinant amino acids (aa) 119–152 of HBsAg into the truncated HBc (aa 1–144), between Asp{sup 78} and Pro{sup 79}. Prokaryotic expression showed that the mosaic HBc was mainly in the form of inclusion bodies. After denaturation with urea, it was dialyzed progressively for protein renaturation. We observed that before and after renaturation, mosaic HBc was antigenic as determined by HBsAg ELISA and a lot of viruslike particles were observed after renaturation. Thus, we further purified the mosaic viruslike particles by (NH{sub 4}){sub 2}SO{sub 4} precipitation, DEAE chromatography, and Sepharose 4FF chromatography. Negative staining electron microscopy demonstrated the morphology of the viruslike particles. Immunization of Balb/c mice with mosaic particles induced the production of anti-HBs antibody and Th1 cell immune response supported by ELISPOT and CD4/CD8 proportions assay. In conclusion, we constructed mosaic hepatitis core particles displaying the entire ‘α’ antigenic determinant on the surface and laid a foundation for researching therapeutic hepatits B vaccines.

  5. Modeling the Mixing of High Concentrations of Bidisperse Cohesive Particles in an Inviscid Binder II

    DTIC Science & Technology

    2010-12-01

    differently-sized particles is already difficult due to such phenomena as the Brazil nut effect. Cohesion between particles (e.g. arising from van der Waals...harder to break up agglomerates can lead to greater and faster “unmixing” (e.g. the Brazil nut effect) ◦ While the strength of cohesion can often be...resulting gravity- driven segregation (e.g. Brazil nut effect) ◦ Properties “after long times” (steady-state?) are of interest ◦ If there is no

  6. Fluorescence anisotropy decay of ethidium bound to nucleosome core particles. 1. Rotational diffusion indicates an extended structure at low ionic strength

    SciTech Connect

    Brown, D.W.; Libertini, L.J.; Small, E.W. )

    1991-05-28

    The fluorescence decay of ethidium intercalated into the DNA of nucleosome core particles increases in average lifetime from about 22 ns in H{sub 2}O to about 39 ns in D{sub 2}O. This increase, combined with the acquisiton of large amounts of data, allows measurement of anisotropy decays out to more than 350 ns. The overall slow rotational motions of the core particle may thereby be more clearly distinguished from the faster torsional motions of the DNA. In 10 mM NaCl at 20{degrees}C, the authors recover a long correlation time of 198 ns in D{sub 2}O (159 ns when corrected to a viscosity of 1.002 cP), in agreement with the value of 164 ns obtained in H{sub 2}O. These values are consistent with hydrodynamic calculations based on the expected size and shape of the hydrated particle. To support their conclusion that this long correlation time derives from Brownian rotational diffusion, they show that the value is directly proportional to the viscosity and inversely proportional to the temperature. No significant changes in the rotational correlation time are observed between 1 and 500 mM ionic strength. Below 1 mM, the particle undergoes the low-salt transition as measured by steady-state tyrosine fluorescence anisotropy. However, they observe little change in shape until the ionic strength is decreased below {approximately}0.2 mM, where the correlation time increases nearly 2-fold, indicating that the particle has opened up into an extended form. They have previously shown that the transition becomes nonreversible below 0.2 mM salt.

  7. Dynamics of Submarine Landslides in an Active Margin from Analysis of Particle Size, Cores, and 3D Seismic Data: Site C0021, IODP Expedition 338, Offshore Japan

    NASA Astrophysics Data System (ADS)

    Sawyer, D.; Moore, Z. T.

    2013-12-01

    The deposits of submarine landslides, termed mass transport deposits (MTDs), were drilled and cored at Site C0021 in the Nankai Trough during Integrated Ocean Drilling Program (IODP) Expedition 338. Two MTDs were identified at 94-117 mbsf and 133-176 mbsf. Each MTD includes mud clasts, tilted bedding, and/or chaotic bedding, an increase in shear strength, a decrease in porosity, the occurrence of shear zones/faults, and a semi-transparent seismic facies. We conducted laser particle size analyses of sediments throughout the entire cored interval at Site C0021 (0 - 5 mbsf and 90 - 194 mbsf). Particle size distributions show that sediments shallower than 155 mbsf are composed of approximately 80% silt-sized, 15% clay-sized, and 5% sand-sized particles. Sediments deeper than 155 mbsf are predominantly composed of approximately 65% silt-sized, 15% clay-sized, and 20% sand-sized particles. MTDs have no obvious differences from non-MTD particle size distributions. We are examining the MTDs to gain insight into their dynamic behavior by mapping them in 3D seismic data. We measure slope geometry, runout distance, and characterize the depositional features preserved within the MTDs in the basal surface, top surface, and internal body. We use slope geometry to calculate regional gravitational shear stress and we use runout distance and morphology as indicators of the dynamic behavior of the landslide. Future work will focus on back-analysis estimates of shear stress and shear strength parameters. Our goal is to distinguish whether these landslides occurred as relatively rapid-moving, low-viscosity events or relatively slow-moving, high-viscosity events. This is an important distinction to make given that initial acceleration of a landslide is a critical variable that determines amplitude of slide-generated tsunami.

  8. Freezing Water with Sized AgI Particles. Part II: Theoretical Considerations.

    DTIC Science & Technology

    as a function of the AgI particle size, shape, and surface structure, critical embryo shape, temperature, and ice-AgI contact angle in water. The...rate is inconsistent with the large uncertainty in the value of the contact angle . As a consequence, classical theory could account for the

  9. Synthesis of sol-gel silica particles in reverse micelles with mixed-solvent polar cores: tailoring nanoreactor structure and properties

    NASA Astrophysics Data System (ADS)

    Bürglová, Kristýna; Hlaváč, Jan; Bartlett, John R.

    2015-07-01

    In this paper, we describe a new approach for producing metal oxide nano- and microparticles via sol-gel processing in confined media (sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles), in which the chemical and physical properties of the polar aqueous core of the reverse micelles are modulated by the inclusion of a second polar co-solvent. The co-solvents were selected for their capacity to solubilise compounds with low water solubility and included dimethylsulfoxide, dimethylformamide, ethylene glycol, n-propanol, dimethylacetamide and N-methylpyrrolidone. A broad range of processing conditions across the sodium bis(2-ethylhexyl)sulfosuccinate/cyclohexane/water phase diagram were identified that are suitable for preparing particles with dimensions <50 to >500 nm. In contrast, only a relatively narrow range of processing conditions were suitable for preparing such particles in the absence of the co-solvents, highlighting the role of the co-solvent in modulating the properties of the polar core of the reverse micelles. A mechanism is proposed that links the interactions between the various reactive sites on the polar head group of the surfactant and the co-solvent to the nucleation and growth of the particles.

  10. An assessment of global and regional sea level for years 1993-2007 in a suite of interannual CORE-II simulations

    NASA Astrophysics Data System (ADS)

    Griffies, Stephen M.; Yin, Jianjun; Durack, Paul J.; Goddard, Paul; Bates, Susan C.; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Böning, Claus W.; Bozec, Alexandra; Chassignet, Eric; Danabasoglu, Gokhan; Danilov, Sergey; Domingues, Catia M.; Drange, Helge; Farneti, Riccardo; Fernandez, Elodie; Greatbatch, Richard J.; Holland, David M.; Ilicak, Mehmet; Large, William G.; Lorbacher, Katja; Lu, Jianhua; Marsland, Simon J.; Mishra, Akhilesh; George Nurser, A. J.; Salas y Mélia, David; Palter, Jaime B.; Samuels, Bonita L.; Schröter, Jens; Schwarzkopf, Franziska U.; Sidorenko, Dmitry; Treguier, Anne Marie; Tseng, Yu-heng; Tsujino, Hiroyuki; Uotila, Petteri; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Winton, Michael; Zhang, Xuebin

    2014-06-01

    We provide an assessment of sea level simulated in a suite of global ocean-sea ice models using the interannual CORE atmospheric state to determine surface ocean boundary buoyancy and momentum fluxes. These CORE-II simulations are compared amongst themselves as well as to observation-based estimates. We focus on the final 15 years of the simulations (1993-2007), as this is a period where the CORE-II atmospheric state is well sampled, and it allows us to compare sea level related fields to both satellite and in situ analyses. The ensemble mean of the CORE-II simulations broadly agree with various global and regional observation-based analyses during this period, though with the global mean thermosteric sea level rise biased low relative to observation-based analyses. The simulations reveal a positive trend in dynamic sea level in the west Pacific and negative trend in the east, with this trend arising from wind shifts and regional changes in upper 700 m ocean heat content. The models also exhibit a thermosteric sea level rise in the subpolar North Atlantic associated with a transition around 1995/1996 of the North Atlantic Oscillation to its negative phase, and the advection of warm subtropical waters into the subpolar gyre. Sea level trends are predominantly associated with steric trends, with thermosteric effects generally far larger than halosteric effects, except in the Arctic and North Atlantic. There is a general anti-correlation between thermosteric and halosteric effects for much of the World Ocean, associated with density compensated changes.

  11. Particle-in-cell simulations of magnetic reconnection in laser-plasma experiments on Shenguang-II facility

    SciTech Connect

    Lu, San; Lu, Quanming; Huang, Can; Wang, Shui; Dong, Quanli; Zhu, Jianqiang; Sheng, Zhengming; Zhang, Jie

    2013-11-15

    Recently, magnetic reconnection has been realized in high-energy-density laser-produced plasmas. Plasma bubbles with self-generated magnetic fields are created by focusing laser beams to small-scale spots on a foil. The bubbles expand into each other, which may then drive magnetic reconnection. The reconnection experiment in laser-produced plasmas has also been conducted at Shenguang-II (SG-II) laser facility, and the existence of a plasmoid was identified in the experiment [Dong et al., Phys. Rev. Lett. 108, 215001 (2012)]. In this paper, by performing two-dimensional (2-D) particle-in-cell simulations, we investigate such a process of magnetic reconnection based on the experiment on SG-II facility, and a possible explanation for the formation of the plasmoid is proposed. The results show that before magnetic reconnection occurs, the bubbles squeeze strongly each other and a very thin current sheet is formed. The current sheet is unstable to the tearing mode instability, and we can then observe the formation of plasmoid(s) in such a multiple X-lines reconnection.

  12. Nearly lattice matched all wurtzite CdSe/ZnTe type II core-shell nanowires with epitaxial interfaces for photovoltaics

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Rai, Satish C.; Marmon, Jason; Chen, Jiajun; Yao, Kun; Wozny, Sarah; Cao, Baobao; Yan, Yanfa; Zhang, Yong; Zhou, Weilie

    2014-03-01

    Achieving a high-quality interface is of great importance in core-shell nanowire solar cells, as it significantly inhibits interfacial recombination and thus improves the photovoltaic performance. Combining thermal evaporation of CdSe and pulsed laser deposition of ZnTe, we successfully synthesized nearly lattice matched all wurtzite CdSe/ZnTe core-shell nanowires on silicon substrates. Comprehensive morphological and structural characterizations revealed that a wurtzite ZnTe shell layer epitaxially grows over a wurtzite CdSe core nanowire with an abrupt interface. Further optical studies confirmed a high-quality interface and demonstrated efficient charge separation induced by the type-II band alignment. A representative photovoltaic device has been demonstrated and yielded an energy-conversion efficiency of 1.7% which can be further improved by surface passivation. The all-wurtzite core-shell nanowire with an epitaxial interface offers an attractive platform to explore the piezo-phototronic effect and promises an efficient hybrid nano-sized, energy harvesting system.Achieving a high-quality interface is of great importance in core-shell nanowire solar cells, as it significantly inhibits interfacial recombination and thus improves the photovoltaic performance. Combining thermal evaporation of CdSe and pulsed laser deposition of ZnTe, we successfully synthesized nearly lattice matched all wurtzite CdSe/ZnTe core-shell nanowires on silicon substrates. Comprehensive morphological and structural characterizations revealed that a wurtzite ZnTe shell layer epitaxially grows over a wurtzite CdSe core nanowire with an abrupt interface. Further optical studies confirmed a high-quality interface and demonstrated efficient charge separation induced by the type-II band alignment. A representative photovoltaic device has been demonstrated and yielded an energy-conversion efficiency of 1.7% which can be further improved by surface passivation. The all-wurtzite core

  13. Insight into selectivity of peptidomimetic inhibitors with modified statine core for plasmepsin II of Plasmodium falciparum over human cathepsin D.

    PubMed

    Dali, Brice; Keita, Melalie; Megnassan, Eugene; Frecer, Vladimir; Miertus, Stanislav

    2012-04-01

    Plasmepsin II (PlmII), an aspartic protease expressed in the food vacuole of Plasmodium falciparum (pf), cleaves the hemoglobin of the host during the erythrocytic stage of the parasite life cycle. Various peptidomimetic inhibitors of PlmII reported so far discriminate poorly between the drug target and aspartic proteases of the host organism, e.g., human cathepsinD (hCatD). hCatD is a protein digestion enzyme and signaling molecule involved in a variety of physiological processes; therefore, inhibition of hCatD by PlmII inhibitors may lead to pathophysiological conditions. In this study, binding of PlmII inhibitors has been modeled using the crystal structures of pfPlmII and hCatD complexes to gain insight into structural requirements underlying the target selectivity. A series of 26 inhibitors were modeled in the binding clefts of the pfPlmII and hCatD to establish QSAR models of the protease inhibition. In addition, 3D-QSAR pharmacophore models were generated for each enzyme. It was concluded that the contributions of the P(2) and P(3') residues to the inhibitor's binding affinity are responsible for the target selectivity. Based on these findings, new inhibitor candidates were designed with predicted inhibition constants K (pre)(i PlmII) reaching 0.2nm and selectivity index (S.I.)=K(pre)(i PlmII) >1200.

  14. Using ACIS on the Chandra X-ray Observatory as a Particle Radiation Monitor II

    NASA Technical Reports Server (NTRS)

    Grant, C. E.; Ford, P. G.; Bautz, M. W.; ODell, S. L.

    2012-01-01

    The Advanced CCD Imaging Spectrometer is an instrument on the Chandra X-ray Observatory. CCDs are vulnerable to radiation damage, particularly by soft protons in the radiation belts and solar storms. The Chandra team has implemented procedures to protect ACIS during high-radiation events including autonomous protection triggered by an on-board radiation monitor. Elevated temperatures have reduced the effectiveness of the on-board monitor. The ACIS team has developed an algorithm which uses data from the CCDs themselves to detect periods of high radiation and a flight software patch to apply this algorithm is currently active on-board the instrument. In this paper, we explore the ACIS response to particle radiation through comparisons to a number of external measures of the radiation environment. We hope to better understand the efficiency of the algorithm as a function of the flux and spectrum of the particles and the time-profile of the radiation event.

  15. Stochastic electrodynamics with particle structure part II - towards a zero-point induced wave behavior

    NASA Astrophysics Data System (ADS)

    Rueda, A.

    1993-04-01

    A previously derived Brownian behavior (paper I) induced by the zero-point field is assumed to hold for a more realistic model. The statistical description of the particle in our model leads naturally to a probabilistic fluid-like description suitable for providing simple intuitive explanations for some well-publicized puzzles of classical stochastic theories like the nodes of the wave-function and the intrinsic spinning (so far nonquantized) of the particles. We confront our result with well-known recent analysis on fractal-like Brownian quantum paths and diffusion in quantum trajectories. It is shown that stochastic electrodynamics may lead to the diffusive fractal-like paths of the Schroedinger theory. A heuristic connection from this Brownian result to Schroedinger's phenomenology is also provided by the Lagrangian density of the probabilistic fluid.

  16. Smoothed particle hydrodynamics model for phase separating fluid mixtures. II. Diffusion in a binary mixture.

    PubMed

    Thieulot, Cedric; Janssen, L P B M; Español, Pep

    2005-07-01

    A previously formulated smoothed particle hydrodynamics model for a phase separating mixture is tested for the case when viscous processes are negligible and only mass and energy diffusive processes take place. We restrict ourselves to the case of a binary mixture that can exhibit liquid-liquid phase separation. The thermodynamic consistency of the model is assessed and the potential of the model to study complex pattern formation in the presence of various thermal boundaries is illustrated.

  17. Three-dimensional gyrokinetic particle-in-cell simulation of plasmas on a massively parallel computer: Final report on LDRD Core Competency Project, FY 1991--FY 1993

    SciTech Connect

    Byers, J.A.; Williams, T.J.; Cohen, B.I.; Dimits, A.M.

    1994-04-27

    One of the programs of the Magnetic fusion Energy (MFE) Theory and computations Program is studying the anomalous transport of thermal energy across the field lines in the core of a tokamak. We use the method of gyrokinetic particle-in-cell simulation in this study. For this LDRD project we employed massively parallel processing, new algorithms, and new algorithms, and new formal techniques to improve this research. Specifically, we sought to take steps toward: researching experimentally-relevant parameters in our simulations, learning parallel computing to have as a resource for our group, and achieving a 100 {times} speedup over our starting-point Cray2 simulation code`s performance.

  18. Coffee rings as low-resource diagnostics: detection of the malaria biomarker Plasmodium falciparum histidine-rich protein-II using a surface-coupled ring of Ni(II)NTA gold-plated polystyrene particles.

    PubMed

    Gulka, Christopher P; Swartz, Joshua D; Trantum, Joshua R; Davis, Keersten M; Peak, Corey M; Denton, Alexander J; Haselton, Frederick R; Wright, David W

    2014-05-14

    We report a novel, low-resource malaria diagnostic platform inspired by the coffee ring phenomenon, selective for Plasmodium falciparum histidine-rich protein-II (PfHRP-II), a biomarker indicative of the P. falciparum parasite strain. In this diagnostic design, a recombinant HRP-II (rcHRP-II) biomarker is sandwiched between 1 μm Ni(II)nitrilotriacetic acid (NTA) gold-plated polystyrene microspheres (AuPS) and Ni(II)NTA-functionalized glass. After rcHRP-II malaria biomarkers had reacted with Ni(II)NTA-functionalized particles, a 1 μL volume of the particle-protein conjugate solution is deposited onto a functionalized glass slide. Drop evaporation produces the radial flow characteristic of coffee ring formation, and particle-protein conjugates are transported toward the drop edge, where, in the presence of rcHRP-II, particles bind to the Ni(II)NTA-functionalized glass surface. After evaporation, a wash with deionized water removes nonspecifically bound materials while maintaining the integrity of the surface-coupled ring produced by the presence of the protein biomarker. The dynamic range of this design was found to span 3 orders of magnitude, and rings are visible with the naked eye at protein concentrations as low as 10 pM, 1 order of magnitude below the 100 pM PfHRP-II threshold recommended by the World Health Organization. Key enabling features of this design are the inert and robust gold nanoshell to reduce nonspecific interactions on the particle surface, inclusion of a water wash step after drop evaporation to reduce nonspecific binding to the glass, a large diameter particle to project a large two-dimensional viewable area after ring formation, and a low particle density to favor radial flow toward the drop edge and reduce vertical settling to the glass surface in the center of the drop. This robust, antibody-free assay offers a simple user interface and clinically relevant limits of biomarker detection, two critical features required for low

  19. Piezo-phototronic Effect Enhanced UV/Visible Photodetector Based on Fully Wide Band Gap Type-II ZnO/ZnS Core/Shell Nanowire Array.

    PubMed

    Rai, Satish C; Wang, Kai; Ding, Yong; Marmon, Jason K; Bhatt, Manish; Zhang, Yong; Zhou, Weilie; Wang, Zhong Lin

    2015-06-23

    A high-performance broad band UV/visible photodetector has been successfully fabricated on a fully wide bandgap ZnO/ZnS type-II heterojunction core/shell nanowire array. The device can detect photons with energies significantly smaller (2.2 eV) than the band gap of ZnO (3.2 eV) and ZnS (3.7 eV), which is mainly attributed to spatially indirect type-II transition facilitated by the abrupt interface between the ZnO core and ZnS shell. The performance of the device was further enhanced through the piezo-phototronic effect induced lowering of the barrier height to allow charge carrier transport across the ZnO/ZnS interface, resulting in three orders of relative responsivity change measured at three different excitation wavelengths (385, 465, and 520 nm). This work demonstrates a prototype UV/visible photodetector based on the truly wide band gap semiconducting 3D core/shell nanowire array with enhanced performance through the piezo-phototronic effect.

  20. MID-INFRARED EXTINCTION MAPPING OF INFRARED DARK CLOUDS. II. THE STRUCTURE OF MASSIVE STARLESS CORES AND CLUMPS

    SciTech Connect

    Butler, Michael J.; Tan, Jonathan C.

    2012-07-20

    We develop the mid-infrared extinction (MIREX) mapping technique of Butler and Tan (Paper I), presenting a new method to correct for the Galactic foreground emission based on observed saturation in independent cores. Using Spitzer GLIMPSE 8 {mu}m images, this allows us to accurately probe mass surface densities, {Sigma}, up to {approx_equal} 0.5 g cm{sup -2} with 2'' resolution and mitigate one of the main sources of uncertainty associated with Galactic MIREX mapping. We then characterize the structure of 42 massive starless and early-stage cores and their surrounding clumps, selected from 10 infrared dark clouds, measuring {Sigma}{sub cl}(r) from the core/clump centers. We first assess the properties of the core/clump at a scale where the total enclosed mass as projected on the sky is M{sub cl} = 60 M{sub Sun }. We find that these objects have a mean radius of R{sub cl} {approx_equal} 0.1 pc, mean {Sigma}{sub cl} = 0.3 g cm{sup -} and, if fitted by a power-law (PL) density profile {rho}{sub cl}{proportional_to}r{sup -k{sub {rho}}{sub ,}{sub c}{sub l}}, a mean value of k{sub {rho},cl} = 1.1. If we assume a core is embedded in each clump and subtract the surrounding clump envelope to derive the core properties, then we find a mean core density PL index of k{sub {rho},c} = 1.6. We repeat this analysis as a function of radius and derive the best-fitting PL plus uniform clump envelope model for each of the 42 core/clumps. The cores have typical masses of M{sub c} {approx} 100 M{sub Sun} and {Sigma}-bar{sub c} {approx} 0.1 g cm{sup -2}, and are embedded in clumps with comparable mass surface densities. We also consider Bonnor-Ebert density models, but these do not fit the observed {Sigma} profiles as well as PLs. We conclude that massive starless cores exist and are well described by singular polytropic spheres. Their relatively low values of {Sigma} and the fact that they are IR dark may imply that their fragmentation is inhibited by magnetic fields rather than

  1. Setting the stage for circumstellar interaction in core-collapse supernovae. II. Wave-driven mass loss in supernova progenitors

    SciTech Connect

    Shiode, Joshua H.; Quataert, Eliot E-mail: eliot@berkeley.edu

    2014-01-01

    Supernovae (SNe) powered by interaction with circumstellar material provide evidence for intense stellar mass loss during the final years before core collapse. We have argued that during and after core neon burning, internal gravity waves excited by core convection can tap into the core fusion power and transport a super-Eddington energy flux out to the stellar envelope, potentially unbinding ∼1 solar mass of material. In this work, we explore the internal conditions of SN progenitors using the MESA one-dimensional stellar evolution code in search of those most susceptible to wave-driven mass loss. We focus on simple, order of magnitude considerations applicable to a wide range of progenitors. Wave-driven mass loss during core neon and oxygen fusion happens preferentially in either lower mass (∼20 solar mass zero-age main sequence) stars or massive, sub-solar metallicity stars. Roughly 20% of the SN progenitors we survey can excite 10{sup 46-48} erg of energy in waves that can potentially drive mass loss within a few months to a decade of core collapse. This energy can generate circumstellar environments with 10{sup –3}-1 solar masses reaching 100 AU before explosion. We predict a correlation between the energy associated with pre-SN mass ejection and the time to core collapse, with the most intense mass loss preferentially occurring closer to core collapse. During silicon burning, wave energy may inflate 10{sup –3}-1 solar masses of the envelope to 10-100 s of solar radii. This suggests that some nominally compact SN progenitors (Type Ibc progenitors) will have a significantly different SN shock breakout signature than traditionally assumed.

  2. A Dual Laser Scanning Confocal and Transmission Electron Microscopy Analysis of the Intracellular Localization, Aggregation and Particle Formation of African Horse Sickness Virus Major Core Protein VP7.

    PubMed

    Wall, Gayle V; Rutkowska, Daria A; Mizrachi, Eshchar; Huismans, Henk; van Staden, Vida

    2017-02-01

    The bulk of the major core protein VP7 in African horse sickness virus (AHSV) self-assembles into flat, hexagonal crystalline particles in a process appearing unrelated to viral replication. Why this unique characteristic of AHSV VP7 is genetically conserved, and whether VP7 aggregation and particle formation have an effect on cellular biology or the viral life cycle, is unknown. Here we investigated how different small peptide and enhanced green fluorescent protein (eGFP) insertions into the VP7 top domain affected VP7 localization, aggregation, and particle formation. This was done using a dual laser scanning confocal and transmission electron microscopy approach in conjunction with analyses of the solubility, aggregation, and fluorescence profiles of the proteins. VP7 top domain modifications did not prevent trimerization, or intracellular trafficking, to one or two discrete sites in the cell. However, modifications that resulted in a misfolded and insoluble VP7-eGFP component blocked trafficking, and precluded protein accumulation at a single cellular site, perhaps by interfering with normal trimer-trimer interactions. Furthermore, the modifications disrupted the stable layering of the trimers into characteristic AHSV VP7 crystalline particles. It was concluded that VP7 trafficking is driven by a balance between VP7 solubility, trimer forming ability, and trimer-trimer interactions.

  3. Thermodynamics of electron transfer in oxygenic photosynthetic reaction centers: volume change, enthalpy, and entropy of electron-transfer reactions in manganese-depleted photosystem II core complexes.

    PubMed

    Hou, J M; Boichenko, V A; Diner, B A; Mauzerall, D

    2001-06-19

    We have previously reported the thermodynamic data of electron transfer in photosystem I using pulsed time-resolved photoacoustics [Hou et al. (2001) Biochemistry 40, 7109-7116]. In the present work, using preparations of purified manganese-depleted photosystem II (PS II) core complexes from Synechocystis sp. PCC 6803, we have measured the DeltaV, DeltaH, and estimated TDeltaS of electron transfer on the time scale of 1 micros. At pH 6.0, the volume contraction of PS II was determined to be -9 +/- 1 A3. The thermal efficiency was found to be 52 +/- 5%, which corresponds to an enthalpy change of -0.9 +/- 0.1 eV for the formation of the state P680+Q(A-) from P680*. An unexpected volume expansion on pulse saturation of PS II was observed, which is reversible in the dark. At pH 9.0, the volume contraction, the thermal efficiency, and the enthalpy change were -3.4 +/- 0.5 A3, 37 +/- 7%, and -1.15 +/- 0.13 eV, respectively. The DeltaV of PS II, smaller than that of PS I and bacterial centers, is assigned to electrostriction and analyzed using the Drude-Nernst equation. To explain the small DeltaV for the formation of P680+Q(A-) or Y(Z*)Q(A-), we propose that fast proton transfer into a polar region is involved in this reaction. Taking the free energy of charge separation of PS II as the difference between the energy of the excited-state P680* and the difference in the redox potentials of the donor and acceptor, the apparent entropy change (TDeltaS) for charge separation of PS II is calculated to be negative, -0.1 +/- 0.1 eV at pH 6.0 (P680+Q(A-)) and -0.2 +/- 0.15 eV at pH 9.0 (Y(Z*)Q(A-)). The thermodynamic properties of electron transfer in PS II core reaction centers thus differ considerably from those of bacterial and PS I reaction centers, which have DeltaV of approximately -27 A3, DeltaH of approximately -0.4 eV, and TDeltaS of approximately +0.4 eV.

  4. Colloidal synthesis and optical properties of type-II CdSe-CdTe and inverted CdTe-CdSe core-wing heteronanoplatelets

    NASA Astrophysics Data System (ADS)

    Antanovich, A. V.; Prudnikau, A. V.; Melnikau, D.; Rakovich, Y. P.; Chuvilin, A.; Woggon, U.; Achtstein, A. W.; Artemyev, M. V.

    2015-04-01

    We developed colloidal synthesis to investigate the structural and electronic properties of CdSe-CdTe and inverted CdTe-CdSe heteronanoplatelets and experimentally demonstrate that the overgrowth of cadmium selenide or cadmium telluride core nanoplatelets with counterpartner chalcogenide wings leads to type-II heteronanoplatelets with emission energies defined by the bandgaps of the CdSe and CdTe platelets and the characteristic band offsets. The observed conduction and valence band offsets of 0.36 eV and 0.56 eV are in line with theoretical predictions. The presented type-II heteronanoplatelets exhibit efficient spatially indirect radiative exciton recombination with a quantum yield as high as 23%. While the exciton lifetime is strongly prolonged in the investigated type-II 2D systems with respect to 2D type-I systems, the occurring 2D giant oscillator strength (GOST) effect still leads to a fast and efficient exciton recombination. This makes type-II heteronanoplatelets interesting candidates for low threshold lasing applications and photovoltaics.We developed colloidal synthesis to investigate the structural and electronic properties of CdSe-CdTe and inverted CdTe-CdSe heteronanoplatelets and experimentally demonstrate that the overgrowth of cadmium selenide or cadmium telluride core nanoplatelets with counterpartner chalcogenide wings leads to type-II heteronanoplatelets with emission energies defined by the bandgaps of the CdSe and CdTe platelets and the characteristic band offsets. The observed conduction and valence band offsets of 0.36 eV and 0.56 eV are in line with theoretical predictions. The presented type-II heteronanoplatelets exhibit efficient spatially indirect radiative exciton recombination with a quantum yield as high as 23%. While the exciton lifetime is strongly prolonged in the investigated type-II 2D systems with respect to 2D type-I systems, the occurring 2D giant oscillator strength (GOST) effect still leads to a fast and efficient exciton

  5. Effects of CO2 on particle size distribution and phytoplankton abundance during a mesocosm bloom experiment (PeECE II)

    NASA Astrophysics Data System (ADS)

    Engel, A.; Schulz, K. G.; Riebesell, U.; Bellerby, R.; Delille, B.; Schartau, M.

    2008-04-01

    The influence of seawater carbon dioxide (CO2) concentration on the size distribution of suspended particles (2-60 μm) and on phytoplankton abundance was investigated during a mesocosm experiment at the large scale facility (LFS) in Bergen, Norway, in the frame of the Pelagic Ecosystem CO2 Enrichment study (PeECE II). In nine outdoor enclosures the partial pressure of CO2 in seawater was modified by an aeration system to simulate past (~190 μatm CO2), present (~370 μatm CO2) and future (~700 μatm CO2) CO2 conditions in triplicates. Due to the initial addition of inorganic nutrients, phytoplankton blooms developed in all mesocosms and were monitored over a period of 19 days. Seawater samples were collected daily for analysing the abundance of suspended particles and phytoplankton with the Coulter Counter and with Flow Cytometry, respectively. During the bloom period, the abundance of small particles (<4 μm) significantly increased at past, and decreased at future CO2 levels. At that time, a direct relationship between the total-surface-to-total-volume ratio of suspended particles and DIC concentration was determined for all mesocosms. Significant changes with respect to the CO2 treatment were also observed in the phytoplankton community structure. While some populations such as diatoms seemed to be insensitive to the CO2 treatment, others like Micromonas spp. increased with CO2, or showed maximum abundance at present day CO2 (i.e. Emiliania huxleyi). The strongest response to CO2 was observed in the abundance of small autotrophic nano-plankton that strongly increased during the bloom in the past CO2 mesocosms. Together, changes in particle size distribution and phytoplankton community indicate a complex interplay between the ability of the cells to physiologically respond to changes in CO2 and size selection. Size of cells is of general importance for a variety of processes in marine systems such as diffusion-limited uptake of substrates, resource allocation

  6. VINE-A NUMERICAL CODE FOR SIMULATING ASTROPHYSICAL SYSTEMS USING PARTICLES. II. IMPLEMENTATION AND PERFORMANCE CHARACTERISTICS

    SciTech Connect

    Nelson, Andrew F.; Wetzstein, M.; Naab, T.

    2009-10-01

    We continue our presentation of VINE. In this paper, we begin with a description of relevant architectural properties of the serial and shared memory parallel computers on which VINE is intended to run, and describe their influences on the design of the code itself. We continue with a detailed description of a number of optimizations made to the layout of the particle data in memory and to our implementation of a binary tree used to access that data for use in gravitational force calculations and searches for smoothed particle hydrodynamics (SPH) neighbor particles. We describe the modifications to the code necessary to obtain forces efficiently from special purpose 'GRAPE' hardware, the interfaces required to allow transparent substitution of those forces in the code instead of those obtained from the tree, and the modifications necessary to use both tree and GRAPE together as a fused GRAPE/tree combination. We conclude with an extensive series of performance tests, which demonstrate that the code can be run efficiently and without modification in serial on small workstations or in parallel using the OpenMP compiler directives on large-scale, shared memory parallel machines. We analyze the effects of the code optimizations and estimate that they improve its overall performance by more than an order of magnitude over that obtained by many other tree codes. Scaled parallel performance of the gravity and SPH calculations, together the most costly components of most simulations, is nearly linear up to at least 120 processors on moderate sized test problems using the Origin 3000 architecture, and to the maximum machine sizes available to us on several other architectures. At similar accuracy, performance of VINE, used in GRAPE-tree mode, is approximately a factor 2 slower than that of VINE, used in host-only mode. Further optimizations of the GRAPE/host communications could improve the speed by as much as a factor of 3, but have not yet been implemented in VINE

  7. Transient particle acceleration in strongly magnetized neutron stars. II - Effects due to a dipole field geometry

    NASA Technical Reports Server (NTRS)

    Fatuzzo, Marco; Melia, Fulvio

    1991-01-01

    Sheared Alfven waves generated by nonradial crustal disturbances above the polar cap of a strongly magnetized neutron star induce an electric field component parallel to B. An attempt is made to determine the manner in which the strong radial dependence of B affects the propagation of these sheared Alfven waves, and whether this MHD process is still an effective particle accelerator. It is found that although the general field equation is quite complicated, a simple wavelike solution can still be obtained under the conditions of interest for which the Alfven phase velocity decouples from the wave equation. The results may be applicable to gamma-ray burst sources.

  8. Vine—A Numerical Code for Simulating Astrophysical Systems Using Particles. II. Implementation and Performance Characteristics

    NASA Astrophysics Data System (ADS)

    Nelson, Andrew F.; Wetzstein, M.; Naab, T.

    2009-10-01

    We continue our presentation of VINE. In this paper, we begin with a description of relevant architectural properties of the serial and shared memory parallel computers on which VINE is intended to run, and describe their influences on the design of the code itself. We continue with a detailed description of a number of optimizations made to the layout of the particle data in memory and to our implementation of a binary tree used to access that data for use in gravitational force calculations and searches for smoothed particle hydrodynamics (SPH) neighbor particles. We describe the modifications to the code necessary to obtain forces efficiently from special purpose "GRAPE" hardware, the interfaces required to allow transparent substitution of those forces in the code instead of those obtained from the tree, and the modifications necessary to use both tree and GRAPE together as a fused GRAPE/tree combination. We conclude with an extensive series of performance tests, which demonstrate that the code can be run efficiently and without modification in serial on small workstations or in parallel using the OpenMP compiler directives on large-scale, shared memory parallel machines. We analyze the effects of the code optimizations and estimate that they improve its overall performance by more than an order of magnitude over that obtained by many other tree codes. Scaled parallel performance of the gravity and SPH calculations, together the most costly components of most simulations, is nearly linear up to at least 120 processors on moderate sized test problems using the Origin 3000 architecture, and to the maximum machine sizes available to us on several other architectures. At similar accuracy, performance of VINE, used in GRAPE-tree mode, is approximately a factor 2 slower than that of VINE, used in host-only mode. Further optimizations of the GRAPE/host communications could improve the speed by as much as a factor of 3, but have not yet been implemented in VINE

  9. Crossover from disordered to core-shell structures of nano-oxide Y2O3 dispersed particles in Fe

    NASA Astrophysics Data System (ADS)

    Higgins, M. P.; Lu, C. Y.; Lu, Z.; Shao, L.; Wang, L. M.; Gao, F.

    2016-07-01

    Molecular dynamic simulations of Y2O3 in bcc Fe and transmission electron microscopy (TEM) observations were used to understand the structure of Y2O3 nano-clusters in an oxide dispersion strengthened steel matrix. The study showed that Y2O3 nano-clusters below 2 nm were completely disordered. Y2O3 nano-clusters above 2 nm, however, form a core-shell structure, with a shell thickness of 0.5-0.7 nm that is independent of nano-cluster size. Y2O3 nano-clusters were surrounded by off-lattice Fe atoms, further increasing the stability of these nano-clusters. TEM was used to corroborate our simulation results and showed a crossover from a disordered nano-cluster to a core-shell structure.

  10. Nearly lattice matched all wurtzite CdSe/ZnTe type II core-shell nanowires with epitaxial interfaces for photovoltaics.

    PubMed

    Wang, Kai; Rai, Satish C; Marmon, Jason; Chen, Jiajun; Yao, Kun; Wozny, Sarah; Cao, Baobao; Yan, Yanfa; Zhang, Yong; Zhou, Weilie

    2014-04-07

    Achieving a high-quality interface is of great importance in core-shell nanowire solar cells, as it significantly inhibits interfacial recombination and thus improves the photovoltaic performance. Combining thermal evaporation of CdSe and pulsed laser deposition of ZnTe, we successfully synthesized nearly lattice matched all wurtzite CdSe/ZnTe core-shell nanowires on silicon substrates. Comprehensive morphological and structural characterizations revealed that a wurtzite ZnTe shell layer epitaxially grows over a wurtzite CdSe core nanowire with an abrupt interface. Further optical studies confirmed a high-quality interface and demonstrated efficient charge separation induced by the type-II band alignment. A representative photovoltaic device has been demonstrated and yielded an energy-conversion efficiency of 1.7% which can be further improved by surface passivation. The all-wurtzite core-shell nanowire with an epitaxial interface offers an attractive platform to explore the piezo-phototronic effect and promises an efficient hybrid nano-sized, energy harvesting system.

  11. A heavy particle comparative study. Part II: cell survival versus depth.

    PubMed

    Raju, M R; Bain, E; Carpenter, S G; Cox, R A; Robertson, J B

    1978-09-01

    Cell-survival measurements with depth of penetration were made for a series of incident doses of proton, helium, carbon, neon, argon, negative pion, neutron, and 60Co photon beams. Cultured human cells (T1) suspended in a gel-containing medium were used, and the measurements were found to be very useful in facilitating the design of ridge filters to produce iso-effects in the region of interest. Heavy charged particle beams (proton, helium, carbon, neon, and negative pion) were found to produce similar cell killing with depth of penetration. Because of saturation effects at higher LET, argon ions were less effective in killing aerated cells at depth, compared with other heavy charged-particle beams. Cell killing at depth in the region of interest, compared with that at the entrance, was not significantly different for single-field exposures when the Bragg peaks were broadened to cover a width of 10 cm. However, when two opposed fields with overlapping peaks were used, a large enhancement in killing was obtained in the peak region.

  12. Conversion of batch to molten glass, II: Dissolution of quartz particles

    SciTech Connect

    Hrma, Pavel R.; Marcial, Jose; Swearingen, Kevin J.; Henager, Samuel H.; Schweiger, Michael J.; Tegrotenhuis, Nathan E.

    2011-01-28

    Quartz dissolution during the batch-to-glass conversion influences the melt viscosity and ultimately the temperature at which the glass forms. Batches to make a high-alumina borosilicate glass (formulated for the vitrification of nuclear waste) were heated as 5°C min-1 and quenched from the temperatures of 400-1200°C at 100°C intervals. As a silica source, the batches contained quartz with particles ranging from 5 to 195 µm. The content of unreacted quartz in the samples was determined with x-ray diffraction. Most of fine quartz has dissolved during the early batch reactions (at temperatures <800°C), whereas coarser quartz dissolved mostly in a continuous glass phase via diffusion. The mass-transfer coefficients were assessed from the data as functions of the initial particle sizes and the temperature. A series of batch was also tested that contained nitrated components and additions of sucrose known to accelerate melting. While sucrose addition had no discernible impact on quartz dissolution, nitrate batches melted somewhat more slowly than batches containing carbonates and hydroxides in addition to nitrates.

  13. Mapping the particle acceleration in the cool core of the galaxy cluster RX J1720.1+2638

    SciTech Connect

    Giacintucci, S.; Markevitch, M.; Brunetti, G.; Venturi, T.; ZuHone, J. A.

    2014-11-01

    We present new deep, high-resolution radio images of the diffuse minihalo in the cool core of the galaxy cluster RX J1720.1+2638. The images have been obtained with the Giant Metrewave Radio Telescope at 317, 617, and 1280 MHz and with the Very Large Array at 1.5, 4.9, and 8.4 GHz, with angular resolutions ranging from 1'' to 10''. This represents the best radio spectral and imaging data set for any minihalo. Most of the radio flux of the minihalo arises from a bright central component with a maximum radius of ∼80 kpc. A fainter tail of emission extends out from the central component to form a spiral-shaped structure with a length of ∼230 kpc, seen at frequencies 1.5 GHz and below. We find indication of a possible steepening of the total radio spectrum of the minihalo at high frequencies. Furthermore, a spectral index image shows that the spectrum of the diffuse emission steepens with increasing distance along the tail. A striking spatial correlation is observed between the minihalo emission and two cold fronts visible in the Chandra X-ray image of this cool core. These cold fronts confine the minihalo, as also seen in numerical simulations of minihalo formation by sloshing-induced turbulence. All these observations favor the hypothesis that the radio-emitting electrons in cluster cool cores are produced by turbulent re-acceleration.

  14. Dissipative particle dynamics simulation of flow generated by two rotating concentric cylinders: II. Lateral dissipative and random forces

    NASA Astrophysics Data System (ADS)

    Filipovic, N.; Haber, S.; Kojic, M.; Tsuda, A.

    2008-02-01

    Traditional DPD methods address dissipative and random forces exerted along the line connecting neighbouring particles. Espanol (1998 Phys. Rev. E 57 2930-48) suggested adding dissipative and random force components in a direction perpendicular to this line. This paper focuses on the advantages and disadvantages of such an addition as compared with the traditional DPD method. Our benchmark system comprises fluid initially at rest occupying the space between two concentric cylinders rotating with various angular velocities. The effect of the lateral force components on the time evolution of the simulated velocity profile was also compared with that of the known analytical solution. The results show that (i) the solution accuracy at steady state has improved and the error has been reduced by at least 30% (in one case by 75%), (ii) the DPD time to reach steady state has been halved, (iii) the CPU time has increased by only 30%, and (iv) no significant differences exist in density and temperature distributions.

  15. Particle simulation of radio frequency stabilization of the flute mode in a tandem mirror. II. Perpendicular antenna

    SciTech Connect

    Abe, H.; Kadoya, Y.

    1988-10-01

    A two-and-a-half-dimensional electromagnetic particle code PS2M (J. Phys. Soc. Jpn. 56, 3899 (1987)) is used to study how an electric field applied perpendicularly to the magnetic field affects the radio frequency stabilization of flute modes in a tandem mirror plasma. The electric field perpendicular to the magnetic field stabilizes or destabilizes the flute mode through the mechanism of the ponderomotive force acting on electrons and ions and through the mechanism of sideband coupling. In the simulations two typical examples have been shown: (i) when the sideband coupling effects (in which the electron terms are dominant) stabilize the flute modes and (ii) when the perpendicular ponderomotive force acting on the electrons destabilizes the flute modes.

  16. Fluoride adsorption from aqueous solution by magnetic core-shell Fe3O4@alginate-La particles fabricated via electro-coextrusion

    NASA Astrophysics Data System (ADS)

    Zhang, Yahui; Lin, Xiaoyan; Zhou, Quisheng; Luo, Xuegang

    2016-12-01

    The magnetic core-shell Fe3O4@Alg-La particles were fabricated successfully by a simple method of electro-coextrusion, and employed as an adsorbent for separation of fluoride from aqueous solution. Main factors affecting the removal of fluoride, including pH, adsorbent dosage, initial concentration, temperature and contact time were investigated. The adsorption isotherm and adsorption kinetics were studied to understand the adsorption process in detail. The experimental data were fitted well by the non-linear Freundlich isotherm and linear pseudo-second-order model, the maximum fluoride adsorption capacity was 45.230 mg/g at pH 4, 298.15 K. Thermodynamic parameters indicated that the fluoride adsorption process was feasible and spontaneous. The presence of other anions like Cl-, SO42-, HCO3- and PO43- had almost no effect on the fluoride adsorption. The adsorbent can be easily separated from the solution by a magnet. The magnetic core-shell Fe3O4@Alg-La particles before and after fluoride adsorption were studied by SEM, FTIR, EDX and XPS, which indicated that the adsorption mechanism may be related to electrostatic attraction and Lewis acid-base interaction.

  17. Occurrence of dead core in catalytic particles containing immobilized enzymes: analysis for the Michaelis-Menten kinetics and assessment of numerical methods.

    PubMed

    Pereira, Félix Monteiro; Oliveira, Samuel Conceição

    2016-11-01

    In this article, the occurrence of dead core in catalytic particles containing immobilized enzymes is analyzed for the Michaelis-Menten kinetics. An assessment of numerical methods is performed to solve the boundary value problem generated by the mathematical modeling of diffusion and reaction processes under steady state and isothermal conditions. Two classes of numerical methods were employed: shooting and collocation. The shooting method used the ode function from Scilab software. The collocation methods included: that implemented by the bvode function of Scilab, the orthogonal collocation, and the orthogonal collocation on finite elements. The methods were validated for simplified forms of the Michaelis-Menten equation (zero-order and first-order kinetics), for which analytical solutions are available. Among the methods covered in this article, the orthogonal collocation on finite elements proved to be the most robust and efficient method to solve the boundary value problem concerning Michaelis-Menten kinetics. For this enzyme kinetics, it was found that the dead core can occur when verified certain conditions of diffusion-reaction within the catalytic particle. The application of the concepts and methods presented in this study will allow for a more generalized analysis and more accurate designs of heterogeneous enzymatic reactors.

  18. Synthesis of zinc oxide-encapsulated poly(methyl methacrylate)-chitosan core-shell hybrid particles and their electrochemical property.

    PubMed

    Petchthanasombat, Chayannan; Tiensing, Tinnakorn; Sunintaboon, Panya

    2012-03-01

    The synthesis of hybrid materials possessing zinc oxide nanoparticles encapsulated in core-shell polymer particles having poly(methyl methacrylate) core and chitosan shell (PMMA-CS/ZnO) was carried out via an emulsifier-free emulsion polymerization. The ZnO nanoparticles modified by 3-(trimethoxysilyl)propyl methacrylate (TPMZnO) were first prepared before being charged to the polymerization system. The effects of polymerization time (from 2 h to 6 h) and the amount of TPMZnO added (0.018 g, 0.020 g, and 0.030 g) were studied. It was found that the polymerization time of 5 h yielded colloidally stable hybrid latex with% MMA conversion up to 90%. Moreover, the increase in the amount of TPMZnO resulted in a decrease in% MMA conversion from 90% to 80%. It was also found from TGA analysis that the amount of TPMZnO added affected the percentage of TPMZnO encapsulation. PMMA-CS/ZnO particles with the size ranging from 173 to 245 nm were observed by TEM. In addition, the PMMA-CS/ZnO hybrid latexes possessed high positive charges in the range of 40-51 mV. The electrochemical property of the electrodes fabricated from PMMA-CS/ZnO nanoparticles was illustrated by cyclic voltammetry.

  19. Alphavirus capsid proteins self-assemble into core-like particles in insect cells: A promising platform for nanoparticle vaccine development.

    PubMed

    Hikke, Mia C; Geertsema, Corinne; Wu, Vincen; Metz, Stefan W; van Lent, Jan W; Vlak, Just M; Pijlman, Gorben P

    2016-02-01

    The mosquito-borne chikungunya virus (CHIKV) causes arthritic diseases in humans, whereas the aquatic salmonid alphavirus (SAV) is associated with high mortality in aquaculture of salmon and trout. Using modern biotechnological approaches, promising vaccine candidates based upon highly immunogenic, enveloped virus-like particles (eVLPs) have been developed. However, the eVLP structure (core, lipid membrane, surface glycoproteins) is more complex than that of non-enveloped, protein-only VLPs, which are structurally and morphologically 'simple'. In order to develop an alternative to alphavirus eVLPs, in this paper we engineered recombinant baculovirus vectors to produce high levels of alphavirus core-like particles (CLPs) in insect cells by expression of the CHIKV and SAV capsid proteins. The CLPs localize in dense nuclear bodies within the infected cell nucleus and are purified through a rapid and scalable protocol involving cell lysis, sonication and low-speed centrifugation steps. Furthermore, an immunogenic epitope from the alphavirus E2 glycoprotein can be successfully fused to the N-terminus of the capsid protein without disrupting the CLP self-assembling properties. We propose that immunogenic epitope-tagged alphavirus CLPs produced in insect cells present a simple and perhaps more stable alternative to alphavirus eVLPs.

  20. A New Multi-dimensional General Relativistic Neutrino Hydrodynamics Code for Core-collapse Supernovae. II. Relativistic Explosion Models of Core-collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Müller, Bernhard; Janka, Hans-Thomas; Marek, Andreas

    2012-09-01

    We present the first two-dimensional general relativistic (GR) simulations of stellar core collapse and explosion with the COCONUT hydrodynamics code in combination with the VERTEX solver for energy-dependent, three-flavor neutrino transport, using the extended conformal flatness condition for approximating the space-time metric and a ray-by-ray-plus ansatz to tackle the multi-dimensionality of the transport. For both of the investigated 11.2 and 15 M ⊙ progenitors we obtain successful, though seemingly marginal, neutrino-driven supernova explosions. This outcome and the time evolution of the models basically agree with results previously obtained with the PROMETHEUS hydro solver including an approximative treatment of relativistic effects by a modified Newtonian potential. However, GR models exhibit subtle differences in the neutrinospheric conditions compared with Newtonian and pseudo-Newtonian simulations. These differences lead to significantly higher luminosities and mean energies of the radiated electron neutrinos and antineutrinos and therefore to larger energy-deposition rates and heating efficiencies in the gain layer with favorable consequences for strong nonradial mass motions and ultimately for an explosion. Moreover, energy transfer to the stellar medium around the neutrinospheres through nucleon recoil in scattering reactions of heavy-lepton neutrinos also enhances the mentioned effects. Together with previous pseudo-Newtonian models, the presented relativistic calculations suggest that the treatment of gravity and energy-exchanging neutrino interactions can make differences of even 50%-100% in some quantities and is likely to contribute to a finally successful explosion mechanism on no minor level than hydrodynamical differences between different dimensions.

  1. A NEW MULTI-DIMENSIONAL GENERAL RELATIVISTIC NEUTRINO HYDRODYNAMICS CODE FOR CORE-COLLAPSE SUPERNOVAE. II. RELATIVISTIC EXPLOSION MODELS OF CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Mueller, Bernhard; Janka, Hans-Thomas; Marek, Andreas E-mail: thj@mpa-garching.mpg.de

    2012-09-01

    We present the first two-dimensional general relativistic (GR) simulations of stellar core collapse and explosion with the COCONUT hydrodynamics code in combination with the VERTEX solver for energy-dependent, three-flavor neutrino transport, using the extended conformal flatness condition for approximating the space-time metric and a ray-by-ray-plus ansatz to tackle the multi-dimensionality of the transport. For both of the investigated 11.2 and 15 M{sub Sun} progenitors we obtain successful, though seemingly marginal, neutrino-driven supernova explosions. This outcome and the time evolution of the models basically agree with results previously obtained with the PROMETHEUS hydro solver including an approximative treatment of relativistic effects by a modified Newtonian potential. However, GR models exhibit subtle differences in the neutrinospheric conditions compared with Newtonian and pseudo-Newtonian simulations. These differences lead to significantly higher luminosities and mean energies of the radiated electron neutrinos and antineutrinos and therefore to larger energy-deposition rates and heating efficiencies in the gain layer with favorable consequences for strong nonradial mass motions and ultimately for an explosion. Moreover, energy transfer to the stellar medium around the neutrinospheres through nucleon recoil in scattering reactions of heavy-lepton neutrinos also enhances the mentioned effects. Together with previous pseudo-Newtonian models, the presented relativistic calculations suggest that the treatment of gravity and energy-exchanging neutrino interactions can make differences of even 50%-100% in some quantities and is likely to contribute to a finally successful explosion mechanism on no minor level than hydrodynamical differences between different dimensions.

  2. The quantum free particle on spherical and hyperbolic spaces: A curvature dependent approach. II

    SciTech Connect

    Carinena, Jose F.; Ranada, Manuel F.; Santander, Mariano

    2012-10-15

    This paper is the second part of a study of the quantum free particle on spherical and hyperbolic spaces by making use of a curvature-dependent formalism. Here we study the analogues, on the three-dimensional spherical and hyperbolic spaces, S{sub {kappa}}{sup 3} ({kappa} > 0) and H{sub k}{sup 3} ({kappa} < 0), to the standard spherical waves in E{sup 3}. The curvature {kappa} is considered as a parameter and for any {kappa} we show how the radial Schroedinger equation can be transformed into a {kappa}-dependent Gauss hypergeometric equation that can be considered as a {kappa}-deformation of the (spherical) Bessel equation. The specific properties of the spherical waves in the spherical case are studied with great detail. These have a discrete spectrum and their wave functions, which are related with families of orthogonal polynomials (both {kappa}-dependent and {kappa}-independent), and are explicitly obtained.

  3. Plasma electron hole kinematics. II. Hole tracking Particle-In-Cell simulation

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Hutchinson, I. H.

    2016-08-01

    The kinematics of a 1-D electron hole is studied using a novel Particle-In-Cell simulation code. A hole tracking technique enables us to follow the trajectory of a fast-moving solitary hole and study quantitatively hole acceleration and coupling to ions. We observe a transient at the initial stage of hole formation when the hole accelerates to several times the cold-ion sound speed. Artificially imposing slow ion speed changes on a fully formed hole causes its velocity to change even when the ion stream speed in the hole frame greatly exceeds the ion thermal speed, so there are no reflected ions. The behavior that we observe in numerical simulations agrees very well with our analytic theory of hole momentum conservation and the effects of "jetting."

  4. Numerical simulations of granular dynamics II: Particle dynamics in a shaken granular material

    NASA Astrophysics Data System (ADS)

    Murdoch, Naomi; Michel, Patrick; Richardson, Derek C.; Nordstrom, Kerstin; Berardi, Christian R.; Green, Simon F.; Losert, Wolfgang

    2012-05-01

    Surfaces of planets and small bodies of our Solar System are often covered by a layer of granular material that can range from a fine regolith to a gravel-like structure of varying depths. Therefore, the dynamics of granular materials are involved in many events occurring during planetary and small-body evolution thus contributing to their geological properties. We demonstrate that the new adaptation of the parallel N-body hard-sphere code pkdgrav has the capability to model accurately the key features of the collective motion of bidisperse granular materials in a dense regime as a result of shaking. As a stringent test of the numerical code we investigate the complex collective ordering and motion of granular material by direct comparison with laboratory experiments. We demonstrate that, as experimentally observed, the scale of the collective motion increases with increasing small-particle additive concentration. We then extend our investigations to assess how self-gravity and external gravity affect collective motion. In our reduced-gravity simulations both the gravitational conditions and the frequency of the vibrations roughly match the conditions on asteroids subjected to seismic shaking, though real regolith is likely to be much more heterogeneous and less ordered than in our idealised simulations. We also show that collective motion can occur in a granular material under a wide range of inter-particle gravity conditions and in the absence of an external gravitational field. These investigations demonstrate the great interest of being able to simulate conditions that are to relevant planetary science yet unreachable by Earth-based laboratory experiments.

  5. MIGRATION AND GROWTH OF PROTOPLANETARY EMBRYOS. II. EMERGENCE OF PROTO-GAS-GIANT CORES VERSUS SUPER EARTH PROGENITORS

    SciTech Connect

    Liu, Beibei; Zhang, Xiaojia; Lin, Douglas N. C.; Aarseth, Sverre J.

    2015-01-01

    Nearly 15%-20% of solar type stars contain one or more gas giant planets. According to the core-accretion scenario, the acquisition of their gaseous envelope must be preceded by the formation of super-critical cores with masses 10 times or larger than that of the Earth. It is natural to link the formation probability of gas giant planets with the supply of gases and solids in their natal disks. However, a much richer population of super Earths suggests that (1) there is no shortage of planetary building block material, (2) a gas giant's growth barrier is probably associated with whether it can merge into super-critical cores, and (3) super Earths are probably failed cores that did not attain sufficient mass to initiate efficient accretion of gas before it is severely depleted. Here we construct a model based on the hypothesis that protoplanetary embryos migrated extensively before they were assembled into bona fide planets. We construct a Hermite-Embryo code based on a unified viscous-irradiation disk model and a prescription for the embryo-disk tidal interaction. This code is used to simulate the convergent migration of embryos, and their close encounters and coagulation. Around the progenitors of solar-type stars, the progenitor super-critical-mass cores of gas giant planets primarily form in protostellar disks with relatively high (≳ 10{sup –7} M {sub ☉} yr{sup –1}) mass accretion rates, whereas systems of super Earths (failed cores) are more likely to emerge out of natal disks with modest mass accretion rates, due to the mean motion resonance barrier and retention efficiency.

  6. Multireversible redox processes in pentanuclear bis(triple-helical) manganese complexes featuring an oxo-centered triangular {Mn(II)2Mn(III)(μ3-O)}5+ or {Mn(II)Mn(III)2(μ3-O)}6+ core wrapped by two {Mn(II)2(bpp)3}-.

    PubMed

    Romain, Sophie; Rich, Jordi; Sens, Cristina; Stoll, Thibaut; Benet-Buchholz, Jordi; Llobet, Antoni; Rodriguez, Montserrat; Romero, Isabel; Clérac, Rodolphe; Mathonière, Corine; Duboc, Carole; Deronzier, Alain; Collomb, Marie-Noëlle

    2011-09-05

    A new pentanuclear bis(triple-helical) manganese complex has been isolated and characterized by X-ray diffraction in two oxidation states: [{Mn(II)(μ-bpp)(3)}(2)Mn(II)(2)Mn(III)(μ-O)](3+) (1(3+)) and [{Mn(II)(μ-bpp)(3)}(2)Mn(II)Mn(III)(2)(μ-O)](4+) (1(4+)). The structure consists of a central {Mn(3)(μ(3)-O)} core of Mn(II)(2)Mn(III) (1(3+)) or Mn(II)Mn(III)(2) ions (1(4+)) which is connected to two apical Mn(II) ions through six bpp(-) ligands. Both cations have a triple-stranded helicate configuration, and a pair of enantiomers is present in each crystal. The redox properties of 1(3+) have been investigated in CH(3)CN. A series of five distinct and reversible one-electron waves is observed in the -1.0 and +1.50 V potential range, assigned to the Mn(II)(4)Mn(III)/Mn(II)(5), Mn(II)(3)Mn(III)(2)/Mn(II)(4)Mn(III), Mn(II)(2)Mn(III)(3)/Mn(II)(3)Mn(III)(2), Mn(II)Mn(III)(4)/Mn(II)(2)Mn(III)(3), and Mn(III)(5)/Mn(II)Mn(III)(4) redox couples. The two first oxidation processes leading to Mn(II)(3)Mn(III)(2) (1(4+)) and Mn(II)(2)Mn(III)(3) (1(5+)) are related to the oxidation of the Mn(II) ions of the central core and the two higher oxidation waves, close in potential, are thus assigned to the oxidation of the two apical Mn(II) ions. The 1(4+) and 1(5+) oxidized species and the reduced Mn(4)(II) (1(2+)) species are quantitatively generated by bulk electrolyses demonstrating the high stability of the pentanuclear structure in four oxidation states (1(2+) to 1(5+)). The spectroscopic characteristics (X-band electron paramagnetic resonance, EPR, and UV-visible) of these species are also described as well as the magnetic properties of 1(3+) and 1(4+) in solid state. The powder X- and Q-band EPR signature of 1(3+) corresponds to an S = 5/2 spin state characterized by a small zero-field splitting parameter (|D| = 0.071 cm(-1)) attributed to the two apical Mn(II) ions. At 40 K, the magnetic behavior is consistent for 1(3+) with two apical S = 5/2 {Mn(II)(bpp)(3)}(-) and one S

  7. Probabilistic evidential assessment of gunshot residue particle evidence (Part II): Bayesian parameter estimation for experimental count data.

    PubMed

    Biedermann, A; Bozza, S; Taroni, F

    2011-03-20

    Part I of this series of articles focused on the construction of graphical probabilistic inference procedures, at various levels of detail, for assessing the evidential value of gunshot residue (GSR) particle evidence. The proposed models--in the form of Bayesian networks--address the issues of background presence of GSR particles, analytical performance (i.e., the efficiency of evidence searching and analysis procedures) and contamination. The use and practical implementation of Bayesian networks for case pre-assessment is also discussed. This paper, Part II, concentrates on Bayesian parameter estimation. This topic complements Part I in that it offers means for producing estimates usable for the numerical specification of the proposed probabilistic graphical models. Bayesian estimation procedures are given a primary focus of attention because they allow the scientist to combine (his/her) prior knowledge about the problem of interest with newly acquired experimental data. The present paper also considers further topics such as the sensitivity of the likelihood ratio due to uncertainty in parameters and the study of likelihood ratio values obtained for members of particular populations (e.g., individuals with or without exposure to GSR).

  8. Polarization-modulated infrared spectroscopy and x-ray reflectivity of photosystem II core complex at the gas-water interface.

    PubMed Central

    Gallant, J; Desbat, B; Vaknin, D; Salesse, C

    1998-01-01

    The state of photosystem II core complex (PS II CC) in monolayer at the gas-water interface was investigated using in situ polarization-modulated infrared reflection absorption spectroscopy and x-ray reflectivity techniques. Two approaches for preparing and manipulating the monolayers were examined and compared. In the first, PS II CC was compressed immediately after spreading at an initial surface pressure of 5.7 mN/m, whereas in the second, the monolayer was incubated for 30 min at an initial surface pressure of 0.6 mN/m before compression. In the first approach, the protein complex maintained its native alpha-helical conformation upon compression, and the secondary structure of PS II CC was found to be stable for 2 h. The second approach resulted in films showing stable surface pressure below 30 mN/m and the presence of large amounts of beta-sheets, which indicated denaturation of PS II CC. Above 30 mN/m, those films suffered surface pressure instability, which had to be compensated by continuous compression. This instability was correlated with the formation of new alpha-helices in the film. Measurements at 4 degreesC strongly reduced denaturation of PS II CC. The x-ray reflectivity studies indicated that the spread film consists of a single protein layer at the gas-water interface. Altogether, this study provides direct structural and molecular information on membrane proteins when spread in monolayers at the gas-water interface. PMID:9826610

  9. PREFACE: Proceedings of the TeV Particle Astrophysics II Workshop

    NASA Astrophysics Data System (ADS)

    Halzen, F.; Karle, A.; Montaruli, T.

    2007-03-01

    The idea of having this workshop in Madison was born at a table on the Terrace of the Union one evening in summer 2005. Francis Halzen, Albrecht Karle and I had just attended the first TeV meeting at Fermilab. We wished to convene the community of particle physicists and "new astronomers" who were using particles to study the universe, in order to hear about their activities and the methods they were using. All of us wanted this to be a meeting between both younger and more experienced people, and both experimentalists and theorists with a common background: dealing with signals produced in the universe that are not controlled by humans. We decided to ask the organizers of the Fermilab workshop to have a second edition in Madison. The next edition is planned for summer 2007 in the Venice region of Italy. To make the meeting more productive, we planned to have a relevant number of working group sessions and open discussions chaired by invited conveners. We singled out seven main areas for discussion at the Workshop with self-explaining names, calling the afternoon sessions Working Groups in those areas: 1) Gamma Astronomy, 2) Ultra-High-Energy Cosmic Rays, 3) Dark Matter, 4) Neutrino Astronomy, 5) New Technologies, 6) TeV Particle (i.e., connections between cosmic-ray, high-energy and accelerator physics) and 7) Gravitational Waves. The conveners had to not only organize the schedules, but also had the unfortunate task of summarizing all of the discussions which took place in their sessions for a presentation on the last day of the conference. Our web site ( http://www.icecube.wisc.edu/tev), developed by Rene Shei, allowed anybody to submit a proposal for a talk to the conveners of the appropriate Working Group(s). We felt that allowing this possibility provided an excellent chance for unknown young students to offer interesting proposals that could then be selected. These Proceedings collect the work of a large number of experts and extremely active representative

  10. Characterization of the low-temperature triplet state of chlorophyll in photosystem II core complexes: Application of phosphorescence measurements and Fourier transform infrared spectroscopy.

    PubMed

    Zabelin, Alexey A; Neverov, Konstantin V; Krasnovsky, Alexander A; Shkuropatova, Valentina A; Shuvalov, Vladimir A; Shkuropatov, Anatoly Ya

    2016-06-01

    Phosphorescence measurements at 77 K and light-induced FTIR difference spectroscopy at 95 K were applied to study of the triplet state of chlorophyll a ((3)Chl) in photosystem II (PSII) core complexes isolated from spinach. Using both methods, (3)Chl was observed in the core preparations with doubly reduced primary quinone acceptor QA. The spectral parameters of Chl phosphorescence resemble those in the isolated PSII reaction centers (RCs). The main spectral maximum and the lifetime of the phosphorescence corresponded to 955±1 nm and of 1.65±0.05 ms respectively; in the excitation spectrum, the absorption maxima of all core complex pigments (Chl, pheophytin a (Pheo), and β-carotene) were observed. The differential signal at 1667(-)/1628(+)cm(-1) reflecting a downshift of the stretching frequency of the 13(1)-keto C=O group of Chl was found to dominate in the triplet-minus-singlet FTIR difference spectrum of core complexes. Based on FTIR results and literature data, it is proposed that (3)Chl is mostly localized on the accessory chlorophyll that is in triplet equilibrium with P680. Analysis of the data suggests that the Chl triplet state responsible for the phosphorescence and the FTIR difference spectrum is mainly generated due to charge recombination in the reaction center radical pair P680(+)PheoD1(-), and the energy and temporal parameters of this triplet state as well as the molecular environment and interactions of the triplet-bearing Chl molecule are similar in the PSII core complexes and isolated PSII RCs.

  11. Fabrication and electromagnetic properties of bio-based helical soft-core particles by way of Ni-Fe alloy electroplating

    NASA Astrophysics Data System (ADS)

    Lan, Mingming; Zhang, Deyuan; Cai, Jun; Zhang, Wenqiang; Yuan, Liming

    2011-12-01

    Ni-Fe alloy electroplating was used as a bio-limited forming process to fabricate bio-based helical soft-core ferromagnetic particles, and a low frequency vibration device was applied to the cathode to avoid microorganism (Spirulina platens) cells adhesion to the copper net during the course of plating. The morphologies and ingredients of the coated Spirulina cells were characterized using scanning electron microscopy and energy dispersive spectrometer. The complex permittivity and permeability of the samples containing the coated Spirulina cells before and after heat treatment were measured and investigated by a vector network analyzer. The results show that the Spirulina cells after plating keep their initial helical shape, and applying low frequency vibration to the copper net cathode in the plating process can effectively prevent agglomeration and intertwinement of the Spirulina cells. The microwave absorbing and electromagnetic properties of the samples containing the coated Spirulina cells particles with heat treatment are superior to those samples containing the coated Spirulina cells particles without heat treatment.

  12. Physics with gamma-beams and charged particle detectors: I) Nuclear structure II) Nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2015-02-01

    The Charged Particle Working Group (CPWG) is proposing to construct large area Silicon Strip Detector (SSD), a gas Time Projection Chamber detector read by an electronic readout system (eTPC) and a Bubble Chamber (BC) containing superheated high purity water to be used in measurements utilizing intense gamma-ray beams from the newly constructed ELI-NP facility at Magurele, Bucharest in Romania. We intend to use the SSD and eTPC detectors to address essential problems in nuclear structure physics, such as clustering and the many alpha-decay of light nuclei such as 12C and 16O . All three detectors (SSD, eTPC and BC) will be used to address central problems in nuclear astrophysics such as the astrophysical cross section factor of the 12C (α,γ) reaction and other processes central to stellar evolution. The CPWG intends to submit to the ELI-NP facility a Technical Design Report (TDR) for the proposed detectors.

  13. Interstellar Neutral Helium in the Heliosphere from IBEX Observations. II. The Warsaw Test Particle Model (WTPM)

    NASA Astrophysics Data System (ADS)

    Sokół, J. M.; Kubiak, M. A.; Bzowski, M.; Swaczyna, P.

    2015-10-01

    We have developed a refined and optimized version of the Warsaw Test Particle Model of interstellar neutral gas in the heliosphere, specially tailored for analysis of IBEX-Lo observations. The former version of the model was used in the analysis of neutral He observed by IBEX that resulted in an unexpected conclusion that the interstellar neutral He flow vector was different than previously thought and that a new population of neutral He, dubbed the Warm Breeze, exists in the heliosphere. It was also used in the reanalysis of Ulysses observations that confirmed the original findings on the flow vector, but suggested a significantly higher temperature. The present version of the model has two strains targeted for different applications, based on an identical paradigm, but differing in the implementation and in the treatment of ionization losses. We present the model in detail and discuss numerous effects related to the measurement process that potentially modify the resulting flux of ISN He observed by IBEX, and identify those of them that should not be omitted in the simulations to avoid biasing the results. This paper is part of a coordinated series of papers presenting the current state of analysis of IBEX-Lo observations of ISN He. Details of the analysis method are presented by Swaczyna et al. and results of the analysis are presented by Bzowski et al.

  14. Quasinormal ringing of Kerr black holes. II. Excitation by particles falling radially with arbitrary energy

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongyang; Berti, Emanuele; Cardoso, Vitor

    2013-08-01

    The analytical understanding of quasinormal mode ringing requires an accurate knowledge of the Green’s function describing the response of the black hole to external perturbations. We carry out a comprehensive study of quasinormal mode excitation for Kerr black holes. Relying on the formalism developed by Mano, Suzuki, and Takasugi, we improve and extend previous calculations of the quasinormal mode residues in the complex frequency plane (“excitation factors Bq”). Using these results we compute the “excitation coefficients” Cq (essentially the mode amplitudes) in the special case where the source of the perturbations is a particle falling into the black hole along the symmetry axis. We compare this calculation with numerical integrations of the perturbation equations, and we show quantitatively how the addition of higher overtones improves the agreement with the numerical waveforms. Our results should find applications in models of the ringdown stage and in the construction of semianalytical template banks for gravitational-wave detectors, especially for binaries with large mass ratios and/or fast-spinning black holes.

  15. ENERGETIC PARTICLE ANISOTROPIES AT THE HELIOSPHERIC BOUNDARY. II. TRANSIENT FEATURES AND RIGIDITY DEPENDENCE

    SciTech Connect

    Florinski, V.; Roux, J. A. le; Stone, E. C.; Cummings, A. C.

    2015-04-10

    In the preceding paper, we showed that large second-order anisotropies of heliospheric ions measured by the Voyager 1 space probe during the August 2012 boundary crossing event could be explained by a magnetic shear across the heliopause preventing particles streaming along the magnetic field from escaping the inner heliosheath. According to Stone et al., the penetration distance of heliospheric ions into the outer heliosheath had a strong dependence on the particle’s Larmor radius. By comparing hydrogen, helium, and oxygen ions with the same energy per nucleon, these authors argued that this effect must be attributed to larger cyclotron radii of heavier species rather than differences in velocity. We propose that gradient drift in a nonuniform magnetic field was the cause of both the large second-order anisotropies and the spatial differentiation based on the ion’s rigidity. A latitudinal gradient of magnetic field strength of about 10% per AU between 2012.7 and 2012.9 could have provided drift motion sufficient to match both LECP and CRS Voyager 1 observations. We explain the transient intensity dropout observed prior to the heliocliff using flux tube structures embedded in the heliosheath and magnetically connected to interstellar space. Finally, this paper reports a new indirect measurement of the plasma radial velocity at the heliopause on the basis of the time difference between two cosmic-ray telescopes measuring the same intensity dropout.

  16. Physics with gamma-beams and charged particle detectors: I) Nuclear structure II) Nuclear astrophysics

    SciTech Connect

    Gai, Moshe

    2015-02-24

    The Charged Particle Working Group (CPWG) is proposing to construct large area Silicon Strip Detector (SSD), a gas Time Projection Chamber detector read by an electronic readout system (eTPC) and a Bubble Chamber (BC) containing superheated high purity water to be used in measurements utilizing intense gamma-ray beams from the newly constructed ELI-NP facility at Magurele, Bucharest in Romania. We intend to use the SSD and eTPC detectors to address essential problems in nuclear structure physics, such as clustering and the many alpha-decay of light nuclei such as {sup 12}C and {sup 16}O. All three detectors (SSD, eTPC and BC) will be used to address central problems in nuclear astrophysics such as the astrophysical cross section factor of the {sup 12}C(α,γ) reaction and other processes central to stellar evolution. The CPWG intends to submit to the ELI-NP facility a Technical Design Report (TDR) for the proposed detectors.

  17. Cosmic-Ray Transport in Heliospheric Magnetic Structures. II. Modeling Particle Transport through Corotating Interaction Regions

    NASA Astrophysics Data System (ADS)

    Kopp, Andreas; Wiengarten, Tobias; Fichtner, Horst; Effenberger, Frederic; Kühl, Patrick; Heber, Bernd; Raath, Jan-Louis; Potgieter, Marius S.

    2017-03-01

    The transport of cosmic rays (CRs) in the heliosphere is determined by the properties of the solar wind plasma. The heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric CR transport are structures such as corotating interaction regions (CIRs), which, due to the enhancement of the magnetic field strength and magnetic fluctuations within and due to the associated shocks as well as stream interfaces, do influence the CR diffusion and drift. In a three-fold series of papers, we investigate these effects by modeling inner-heliospheric solar wind conditions with the numerical magnetohydrodynamic (MHD) framework Cronos (Wiengarten et al., referred as Paper I), and the results serve as input to a transport code employing a stochastic differential equation approach (this paper). While, in Paper I, we presented results from 3D simulations with Cronos, the MHD output is now taken as an input to the CR transport modeling. We discuss the diffusion and drift behavior of Galactic cosmic rays using the example of different theories, and study the effects of CIRs on these transport processes. In particular, we point out the wide range of possible particle fluxes at a given point in space resulting from these different theories. The restriction of this variety by fitting the numerical results to spacecraft data will be the subject of the third paper of this series.

  18. On the cubic zero-order solution of electromagnetic waves. II. Isolated particles with lossy plasmas

    SciTech Connect

    Lee, Hyoung-In; Mok, Jinsik

    2010-07-15

    Electromagnetic waves are examined for a single isolated nanoparticle, which is composed of lossy plasmonic components and immersed in an unbounded homogeneous dielectric host medium. Wave characteristics thus obtained on resonance play crucial roles as the zero-order solution for periodic structures such as linear particle chains. The dispersion relation with cubic nonlinearity in frequency accounts for radiation damping in addition to dynamic depolarization. It is theoretically analyzed on the parameter plane spanned by the material loss and the plasma frequency. As in the preceding companion paper of Paper I, analysis shows two types of solutions: propagating waves and stationary states. In addition, the temporal attenuation rate exhibits a maximum feature at a certain material loss in confirmation of experimental results. However, physical behaviors of a nanoparticle turn out quite distinct from those illustrated in Paper I. The reasons are that the different mathematical structures are involved, and different geometries require different underlying assumptions. In special, the issue of series convergence in choosing proper solutions will be addressed. In addition, solutions to nanoparticles made of polarizable dielectric materials are found not to exist.

  19. Directional statistics for realistic weakly interacting massive particle direct detection experiments. II. 2D readout

    NASA Astrophysics Data System (ADS)

    Morgan, Ben; Green, Anne M.

    2005-12-01

    The direction dependence of the WIMP direct detection rate provides a powerful tool for distinguishing a WIMP signal from possible backgrounds. We study the number of events required to discriminate a WIMP signal from an isotropic background for a detector with 2-d readout using nonparametric circular statistics. We also examine the number of events needed to (i) detect a deviation from rotational symmetry, due to flattening of the Milky Way halo and (ii) detect a deviation in the mean direction due to a tidal stream. If the senses of the recoils are measured then of order 20--70 events (depending on the plane of the 2-d readout and the detector location) will be sufficient to reject isotropy of the raw recoil angles at 90% confidence. If the senses can not be measured these number increase by roughly 2 orders of magnitude (compared with an increase of 1 order of magnitude for the case of full 3-d readout). The distributions of the reduced angles, with the (time-dependent) direction of solar motion subtracted, are far more anisotropic, however, and if the isotropy tests are applied to these angles then the numbers of events required are similar to the case of 3-d readout. A deviation from rotational symmetry will only be detectable if the Milky Way halo is significantly flattened. The deviation in the mean direction due to a tidal stream is potentially detectable, however, depending on the density and direction of the stream. The meridian plane (which contains the Earth’s spin axis) is, for all detector locations, the optimum readout plane for rejecting isotropy. However readout in this plane can not be used for detecting flattening of the Milky Way halo or a stream with direction perpendicular to the galactic plane. In these cases the optimum readout plane depends on the detector location.

  20. Core-Shell Ferromagnetic Nanorod Based on Amine Polymer Composite (Fe3O4@DAPF) for Fast Removal of Pb(II) from Aqueous Solutions.

    PubMed

    Venkateswarlu, Sada; Yoon, Minyoung

    2015-11-18

    Heavy metal ion removal from wastewater constitutes an important issue in the water treatment industry. Although a variety of nanomaterials have been developed for heavy metal removal via adsorption, the adsorption capacity, removal efficiency, and material recyclability still remain a challenge. Here, we present novel Fe3O4@DAPF core-shell ferromagnetic nanorods (CSFMNRs) for the removal of Pb(II) from aqueous solutions; they were prepared by the facile surface modification of twin-like ferromagnetic Fe3O4 nanorods using a 2,3-diaminophenol and formaldehyde (DAPF)-based polymer. The crystallinity and structure of the Fe3O4 nanorods were confirmed via X-ray diffraction (XRD). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) revealed the core-shell morphology and composition of the materials. Pb(II) removal using the prepared Fe3O4@DAPF CSFMNRs was assessed, and comparable adsorption capacities (83.3 mg g(-1)) to the largest value were demonstrated. A thermodynamic study of the adsorption clearly indicated that the adsorption was exothermic and spontaneous. Due to the ferromagnetic properties with a high saturation magnetization value (56.1 emu g(-1)) of the nanorods, the nanorods exhibited excellent reusability with one of the fastest recovery times (25 s) among reported materials. Therefore, the Fe3O4@DAPF CSFMNRs can serve as recyclable adsorbent materials and as an alternative to commonly used sorbent materials for the rapid removal of heavy metals from aqueous solutions.

  1. Synthesis, molecular structures and phase transition studies on benzothiazole-cored Schiff bases with their Cu(II) and Pd(II) complexes: Crystal structure of (E)-6-methoxy-2-(4-octyloxy-2-hydroxybenzylideneamino)benzothiazole

    NASA Astrophysics Data System (ADS)

    Yeap, Guan-Yeow; Heng, Boon-Teck; Faradiana, Nur; Zulkifly, Raihana; Ito, Masato M.; Tanabe, Makoto; Takeuchi, Daisuke

    2012-03-01

    Two new homologous series of Cu(II) and Pd(II) complexes with benzothiazole-cored Schiff bases have been synthesised with the aim to study the mesomorphic and thermal properties of ligands upon formation of metal complexes. The molecular structure of title compounds were elucidated with the employment of FT-IR, 1D and 2D FT-NMR spectroscopic techniques. Mesomorphic and thermal behaviour of title compounds have been investigated by differential scanning calorimetry and polarising optical microscope. All the ligands are nematogenic but the corresponding Cu(II) and Pd(II) complexes crystallised in ordinary solid. The conformation of 6-methoxy-2-(4-octyloxy-2-hydroxy-benzylideneamino)benzothiazole was determined by single crystal X-ray diffraction analysis of which the title compound favours more stable (E)-6-methoxy-2-(4-octyloxy-2-hydroxybenzylideneamino)benzothiazole. Crystal structure of the title compound also revealed that the bond length of Cdbnd N (1.303 Å) in the benzothiazole rings very close to that in the exocyclic Cdbnd N linkage (1.298 Å).

  2. Environmentally friendly electroless plating for Ag/TiO2-coated core-shell magnetic particles using ultrasonic treatment.

    PubMed

    Kim, Soo-Dong; Choe, Won-Gyun; Jeong, Jong-Ryul

    2013-11-01

    In this work, high-reflectance brilliant white color magnetic microspheres comprising a Fe/TiO2/Ag core-shell structure with a continuous, uniform compact silver layer were successfully fabricated by TiO2-assisted electroless plating in a simple and eco-friendly method. The coating procedure for TiO2 and Ag involved a sol-gel reaction and electroless plating with ultrasound treatment. The electroless plating step was carried out in an eco-friendly manner in a single process without environmentally toxic additives. The TiO2 layer was used as a modification layer between the Fe microspheres and the silver layer to improve adhesion. A continuous and compact silver layer could be formed with a high degree of morphological control by introducing ultrasonication and adjusting the ammonium hydroxide concentration.

  3. THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. II. SEPARATING LUMINOUS AND DARK MATTER IN CLUSTER CORES

    SciTech Connect

    Newman, Andrew B.; Ellis, Richard S.; Treu, Tommaso; Sand, David J.

    2013-03-01

    We present stellar and dark matter (DM) density profiles for a sample of seven massive, relaxed galaxy clusters derived from strong and weak gravitational lensing and resolved stellar kinematic observations within the centrally located brightest cluster galaxies (BCGs). In Paper I of the series, we demonstrated that the total density profile derived from these data, which span three decades in radius, is consistent with numerical DM-only simulations at radii {approx}> 5-10 kpc, despite the significant contribution of stellar material in the core. Here, we decompose the inner mass profiles of these clusters into stellar and dark components. Parameterizing the DM density profile as a power law {rho}{sub DM}{proportional_to}r {sup -{beta}} on small scales, we find a mean slope ({beta}) = 0.50 {+-} 0.10(random){sup +0.14} {sub -0.13}(systematic). Alternatively, cored Navarro-Frenk-White (NFW) profiles with (log r {sub core}/kpc) = 1.14 {+-} 0.13{sup +0.14} {sub -0.22} provide an equally good description. These density profiles are significantly shallower than canonical NFW models at radii {approx}< 30 kpc, comparable to the effective radii of the BCGs. The inner DM profile is correlated with the distribution of stars in the BCG, suggesting a connection between the inner halo and the assembly of stars in the central galaxy. The stellar mass-to-light ratio inferred from lensing and stellar dynamics is consistent with that inferred using stellar population synthesis models if a Salpeter initial mass function is adopted. We compare these results to theories describing the interaction between baryons and DM in cluster cores, including adiabatic contraction models and the possible effects of galaxy mergers and active galactic nucleus feedback, and evaluate possible signatures of alternative DM candidates.

  4. Paleomagnetism of sedimentary cores from the Ross Sea outer shelf and continental slope (PNRA-ROSSLOPE II Project)

    NASA Astrophysics Data System (ADS)

    Macrì, Patrizia; Sagnotti, Leonardo; Caricchi, Chiara; Colizza, Ester

    2016-04-01

    We carried out a paleomagnetic and rock magnetic study of 4 gravity cores sampled in the Ross Sea continental slope of the area to the east of Pennell-Iselin banks. The cores (RS14-C1, C2, C3 and ANTA99-C20) consist of hemipelagic fine-grained (silty-clays) sediments with an IRD component. Rock magnetic and paleomagnetic measurements were carried out at 1-cm spacing on u-channel samples. The data indicate that the cored sediments carry a well-defined characteristic remanent magnetization (ChRM) and have a valuable potential to reconstruct dynamics and amplitude of the geomagnetic field variation at high southern latitudes (ca. 75°S) during the Holocene and the late Pleistocene. The paleomagnetic and rock magnetic data are integrated in a multidisciplinary context which includes previous geological, geophysical, oceanographic and morpho-bathimetric data obtained in the same area in the frame of the PNRA/ROSSLOPE (Past and present sedimentary dynamic in the ROSS Sea: a multidisciplinary approach to study the continental slope) Project. The main aim of the project is to investigate the relation between present and past water mass circulation and to provide a basis for paleoceanographic reconstructions and for the development of a depositional model of the modern processes active along the continental slope.

  5. Relation Between Clinical Best Practices and 6-Month Outcomes After Transcatheter Aortic Valve Implantation With CoreValve (from the ADVANCE II Study).

    PubMed

    Sinning, Jan-Malte; Petronio, Anna Sonia; Van Mieghem, Nicolas; Zucchelli, Giulio; Nickenig, Georg; Bekeredjian, Raffi; Bosmans, Johan; Bedogni, Francesco; Branny, Marian; Stangl, Karl; Kovac, Jan; Nordell, Anna; Schiltgen, Molly; Piazza, Nicolo; de Jaegere, Peter

    2017-01-01

    Best practices for transcatheter aortic valve implantation with CoreValve include patient screening and valve size selection using multislice computed tomography, adherence to manufacturer recommendations for oversizing, control of implant depth to 6 mm or less, and management of conduction disturbances according to international guidelines. The ADVANCE II study implemented these strategies and demonstrated their relation to clinical outcomes. From October 2011 to April 2013, 200 patients with severe aortic stenosis were enrolled, and 194 were implanted. All imaging and electrocardiographic data were analyzed by an independent core laboratory, and adverse events were adjudicated to valve academic research consortium-2 definitions. The mean age was 80.2 ± 6.7 years and the mean Society of Thoracic Surgeons Predicted Risk of Mortality was 7.2 ± 6.8% for the enrolled patients. At 6 months, all-cause mortality was 9.2%, stroke was 2.6%, and permanent pacemaker implantation was 19.2% for class I and II indications. In patients with implant depth ≤6 mm, both mortality and permanent pacemaker implantation were lower than in patients with depth >6 mm (2.5% vs 14.5%, p <0.01 and 18.1% vs 31.7%, p = 0.03, respectively). The rate of moderate and severe paravalvular leak was 9.8% at 7 days after transcatheter aortic valve implantation, decreasing to 4.3% at 6 months (p = 0.02). Valves were significantly more oversized in patients with mild or less paravalvular leak at day 7 compared with those with moderate or severe (15.8 ± 8.0% vs 11.8 ± 4.9%, p = 0.01). In conclusion, findings from the ADVANCE II study reinforce that adherence to best clinical practices improves patient outcomes.

  6. PARTICLE IMAGE VELOCIMETRY MEASUREMENTS IN A REPRESENTATIVE GAS-COOLED PRISMATIC REACTOR CORE MODEL: FLOW IN THE COOLANT CHANNELS AND INTERSTITIAL BYPASS GAPS

    SciTech Connect

    Thomas E. Conder; Richard Skifton; Ralph Budwig

    2012-11-01

    Core bypass flow is one of the key issues with the prismatic Gas Turbine-Modular Helium Reactor, and it refers to the coolant that navigates through the interstitial, non-cooling passages between the graphite fuel blocks instead of traveling through the designated coolant channels. To determine the bypass flow, a double scale representative model was manufactured and installed in the Matched Index-of-Refraction flow facility; after which, stereo Particle Image Velocimetry (PIV) was employed to measure the flow field within. PIV images were analyzed to produce vector maps, and flow rates were calculated by numerically integrating over the velocity field. It was found that the bypass flow varied between 6.9-15.8% for channel Reynolds numbers of 1,746 and 4,618. The results were compared to computational fluid dynamic (CFD) pre-test simulations. When compared to these pretest calculations, the CFD analysis appeared to under predict the flow through the gap.

  7. Historical record of polycyclic aromatic hydrocarbons (PAHs) and spheroidal carbonaceous particles (SCPs) in marine sediment cores from Admiralty Bay, King George Island, Antarctica.

    PubMed

    Martins, César C; Bícego, Márcia C; Rose, Neil L; Taniguchi, Satie; Lourenço, Rafael A; Figueira, Rubens C L; Mahiques, Michel M; Montone, Rosalinda C

    2010-01-01

    This paper describes the first results of polycyclic aromatic hydrocarbons (PAHs) and spheroidal carbonaceous particles (SCPs) in sediment cores of Admiralty Bay, Antarctica. These markers were used to assess the local input of anthropogenic materials (particulate and organic compounds) as a result of the influence of human occupation in a sub-Antarctic region and a possible long-range atmospheric transport of combustion products from sources in South America. The highest SCPs and PAHs concentrations were observed during the last 30 years, when three research stations were built in the area and industrial activities in South America increased. The concentrations of SCPs and PAHs were much lower than those of other regions in the northern hemisphere and other reported data for the southern hemisphere. The PAH isomer ratios showed that the major sources of PAHs are fossil fuels/petroleum, biomass combustion and sewage contribution generally close to the Brazilian scientific station.

  8. Molecular cloning and expression of human UDP-d-Xylose:proteoglycan core protein beta-d-xylosyltransferase and its first isoform XT-II.

    PubMed

    Götting, C; Kuhn, J; Zahn, R; Brinkmann, T; Kleesiek, K

    2000-12-08

    Human UDP-d-xylose:proteoglycan core protein beta-d-xylosyltransferase (EC 2.4.2.26, XT-I) initiates the biosynthesis of glycosaminoglycan chains in proteoglycans by transferring xylose from UDP-xylose to specific serine residues of the core protein. Based on the partial amino acid sequence of the purified enzyme from human JAR choriocarcinoma cell culture supernatant we isolated a cDNA encoding XT-I using the degenerate reverse transcriptase-polymerase chain reaction method. This enzyme, which is involved in chondroitin sulfate, heparan sulfate, heparin and dermatan sulfate biosynthesis, belongs to a novel family of glycosyltransferases with no homology to proteins known so far. 5' and 3'-RACE were performed to isolate a novel cDNA fragment of 3726 bp with a single open reading frame encoding at least 827 amino acid residues with a molecular mass of 91 kDa. The human XT-I gene was located on chromosome 16p13.1 using radiation hybrid mapping, and extracts from CHO-K1 cells transfected with the XT-I cDNA in an expression vector exhibited marked XT activity. A new 3608 bp cDNA fragment encoding a protein of 865 amino acid residues was also isolated by PCR using degenerate primers based on the amino acid sequence of human XT-I. The amino acid sequence of this XT-II isoform displayed 55% identity to the human XT-I. The XT-II gene was located on chromosome 17q21.3-17q22, and the exon/intron structure of the 15 kb gene was determined. RT-PCR analyses of XT-I and XT-II mRNA from various tissues confirmed that both XT-I and XT-II transcripts are ubiquitously expressed in the human tissues, although with different levels of transcription. Furthermore, the cDNAs encoding XT-I and XT-II from rat were cloned. The deduced amino acid sequences of rat xylosyltransferases displayed 94% identity to the corresponding human enzyme.

  9. A novel synthesis method for TiO2 particles with magnetic Fe3O4 cores.

    PubMed

    Dong, Qi; Zhang, Keqiang; An, Yi

    2014-01-01

    TiO2@(AC/Fe3O4) (AC is activated carbon) was prepared by using AC and Fe3O4 as joint support. The morphological features, crystal structure, and magnetism of the final product were characterized. The results indicate that TiO2 particles formed on the surface of AC and Fe3O4; the sizes of TiO2 and Fe3O4 were 0.5 and 0.7 μm respectively, and that of AC fell within a wide range. The highly crystalline cubic structures of the TiO2 particles was in accord with the standard X-ray diffractometry spectrum of magnetite and anatase. The maximum saturation magnetization of TiO2@(AC/Fe3O4) was 75 emu g(-1), which was enough to support magnetic recovery. The rate of methylene blue (MB) removal photocatalyzed by TiO2@(AC/Fe3O4) was higher by 50% than that achieved with AC/Fe3O4 photocatalysis, and similar to that achieved with TiO2@AC. The removal rate (kobs) decreased drastically from 1.77 × 10(-2) to 9.36 × 10(-3)min(-1) when the initial concentration of MB solution increased from 2.0 to 5.0 mg L(-1). The kobs value increased from 9.41 × 10(-3) to 1.34 × 10(-2)min(-1) with increasing photocatalyst dosage from 0.2 to 1.0 g, then slightly decreased to 1.33 × 10(-2)min(-1) at 2.0 g dosage.

  10. Implementation of multifilter based twin-prototypes for core electron temperature measurements in the TJ-II stellarator

    SciTech Connect

    Baiao, D.; Varandas, C.; Molinero, A.; Chercoles, J.

    2010-10-15

    The design and preliminary results from a prototype of a multifilter based electron temperature diagnostic for the TJ-II stellarator are presented. The diagnostic consists of four photodiodes with filters of different thicknesses to determine the electron temperature in a wide variety of plasma compositions, thanks to the set of six different signal-pairs ratios available. The impurity transport code IONEQ, the TJ-II soft x-ray tomography, and the VUV survey diagnostics give the necessary information to assess the proposed diagnostic reliability. In parallel, a vacuum-compatible multichannel electronic board has been designed for a future linear array to determine electron temperature profiles in high-density plasmas.

  11. Copper(II) cubanes with a {Cu4O} core and well defined S = 1 ground state.

    PubMed

    Escuer, A; Mayans, J; Font-Bardia, M

    2016-01-28

    The reaction of 2-pyridinemethanol with copper 4-fluorobenzoate has yielded a family of type II cubanes with formula [Cu4(pymO)4(4-F-PhCOO)3(NO3)] (), [Cu4(pymO)4(4-F-PhCOO)4] () and [Cu4(pymO)4(4-F-PhCOO)4(H2O)] (). These systems exhibit an unexpected S = 1 ground state and their magnetic properties have been unambiguously characterized and rationalized as a function of the asymmetry of the {Cu4O4} cage and Cu-O-Cu bond angles. Analysis of the coupling constants was performed applying new interaction schemes. Magneto-structural correlations have been performed from the analysis of previously reported type II copper cubanes.

  12. High mobility group protein number17 cross-links primarily to histone H2A in the reconstituted HMG 17 - nucleosome core particle complex

    SciTech Connect

    Cook, G.R.; Yau, P.; Yasuda, H.; Traut, R.R.; Bradbury, E.M.

    1986-05-01

    The neighbor relationship of lamb thymus High Mobility Group (HMG) protein 17 to native HeLa nucleosome core particle histones in the reconstituted complex has been studied. /sup 125/I-labeled HMG 17 was cross-linking to core histones using the protein-protein cross-linking reagent 2-iminothiolane. Specific cross-linked products were separated on a two-dimensional Triton-acid-urea/SDS gel system, located by autoradiography, excised and quantified. Disulfide bonds in the cross links were then cleaved and the protein constituents were identified by SDS gel electrophoresis. HMG 17 cross-linked primarily to histone H2A while lower levels of cross-linking occurred between HMG 17 and the other histones. In contrast, cross-linking between two HMG 17 molecules bound on the same nucleosome was relatively rare. It is concluded that the same nucleosome was relatively rare. It is concluded that H2A comprises part of the HMG 17 binding site but that HMG 17 is sufficiently elongated and mobile to permit cross-linking to the other histones and to a second HMG 17 molecule. These results are in agreement with the current model for the structure of the nucleosome and the proposed binding sites for HMG 17.

  13. Deletion modification enhances anthrax specific immunity and protective efficacy of a hepatitis B core particle-based anthrax epitope vaccine.

    PubMed

    Yin, Ying; Zhang, Sheng; Cai, Chenguang; Zhang, Jun; Dong, Dayong; Guo, Qiang; Fu, Ling; Xu, Junjie; Chen, Wei

    2014-02-01

    Protective antigen (PA) is one of the major virulence factors of anthrax and is also the major constituent of the current anthrax vaccine. Previously, we found that the 2β2-2β3 loop of PA contains a dominant neutralizing epitope, the SFFD. We successfully inserted the 2β2-2β3 loop of PA into the major immunodominant region (MIR) of hepatitis B virus core (HBc) protein. The resulting fusion protein, termed HBc-N144-PA-loop2 (HBcL2), can effectively produce anthrax specific protective antibodies in an animal model. However, the protective immunity caused by HBcL2 could still be improved. In this research, we removed amino acids 79-81 from the HBc MIR of the HBcL2. This region was previously reported to be the major B cell epitope of HBc, and in keeping with this finding, we observed that the short deletion in the MIR not only diminished the intrinsic immunogenicity of HBc but also stimulated a higher titer of anthrax specific immunity. Most importantly, this deletion led to the full protection of the immunized mice against a lethal dose anthrax toxin challenge. We supposed that the conformational changes which occurred after the short deletion and foreign insertion in the MIR of HBc were the most likely reasons for the improvement in the immunogenicity of the HBc-based anthrax epitope vaccine.

  14. Variation of the ground spin state in homo- and hetero-octanuclear copper(II) and nickel(II) double-star complexes with a meso-helicate-type metallacryptand core.

    PubMed

    Pardo, Emilio; Dul, Marie-Claire; Lescouëzec, Rodrigue; Chamoreau, Lise-Marie; Journaux, Yves; Pasán, Jorge; Ruiz-Pérez, Catalina; Julve, Miguel; Lloret, Francesc; Ruiz-García, Rafael; Cano, Joan

    2010-05-28

    Homo- and heterometallic octanuclear complexes of formula Na₂{[Cu₂(mpba)₃][Cu(Me₅dien)]₆}-(ClO₄)₆·12H₂O (1), Na₂{[Cu₂(Mempba)₃][Cu(Me₅dien)]₆}(ClO₄)₆·12H₂O (2), Na₂{[Ni₂(mpba)₃]-[Cu(Me₅dien)]₆}(ClO₄)₆·12H₂O (3), Na₂{[Ni₂(Mempba)₃][Cu(Me₅dien)]₆}(ClO₄)₆·9H₂O (4), {[Ni₂(mpba)₃][Ni(dipn)(H₂O)]₆}(ClO₄)₄·12.5H₂O (5), and {[Ni₂(Mempba)₃][Ni(dipn)-(H₂O)]₆}(ClO₄)₄·12H₂O (6) [mpba = 1,3-phenylenebis(oxamate), Mempba = 4-methyl-1,3-phenylenebis(oxamate), Me₅dien = N,N,N',N'',N''-pentamethyldiethylenetriamine, and dipn = dipropylenetriamine] have been synthesized through the "complex-as-ligand/complex-as-metal" strategy. Single-crystal X-ray diffraction analyses of 1, 3, and 5 show cationic M(II)₂M'(II)₆ entities (M, M' = Cu and Ni) with an overall double-star architecture, which is made up of two oxamato-bridged M(II)M'(II)₃ star units connected through three meta-phenylenediamidate bridges between the two central metal atoms leading to a binuclear metallacryptand core of the meso-helicate-type. Dc magnetic susceptibility data for 1-6 in the temperature range 2-300 K have been analyzed through a "dimer-of-tetramers" model [H = - J(S(1A)·S(3A) + S(1A)·S(4A) + S(1A)·S(5A) + S(2B)·S(6B) + S(2B)·S(7B) + S(2B)·S(8B)) - J'S(1A)·S(2B), with S(1A) = S(2B) = S(M) and S(3A) = S(4A) = S(5A) = S(6B) = S(7B) = S(8B) = S(M')]. The moderate to strong antiferromagnetic coupling between the M(II) and M'(II) ions through the oxamate bridge in 1-6 (-J(Cu-Cu) = 52.0-57.0 cm⁻¹, -J(Ni-Cu) = 39.1-44.7 cm⁻¹, and -J(Ni-Ni) = 26.3-26.6 cm⁻¹) leads to a non-compensation of the ground spin state for the tetranuclear M(II)M'(II)₃ star units [S(A) = S(B) = 3S(M') - S(M) = 1 (1 and 2), 1/2 (3 and 4), and 2 (5 and 6)]. Within the binuclear M(II)₂ meso-helicate cores of 1-4, a moderate to weak antiferromagnetic coupling between the M(II) ions (-J'(Cu-Cu) = 28.0-48.0 cm⁻¹ and -J

  15. Clinical use of a combined grasping and locking core suture technique for flexor tendon repair in zone II.

    PubMed

    Al-Qattan, Mohammad M

    2013-12-01

    Previous authors have used either a grasping or a locking technique for flexor tendon repair in zone II. A combined (grasping and locking) 10-strand repair was used by the author in 22 adults (n = 28 fingers) with lacerations of both flexor tendons in zone II. The combined repair is known to be strong (mean tensile strength of 164 N), and the technique was used in selected cases who were thought to be at higher risk of rupture either because of excessive digital oedema (in early tendon repairs) or because of tendon retraction (in late primary tendon repairs). The 10-strand repair was bulky and, hence, only the profundus tendon was repaired; and "venting" of the pulley system was done proximal to the repair site as recommended by other authors. Supervised early active mobilisation was done immediately after the operation. At final follow-up, the outcome was calculated using the original Strickland-Glogovac grading system. There were no ruptures and the final outcome was considered excellent in 19 patients (n = 25 fingers), good in two patients (n = 2 fingers), and fair in the remaining patient (n = 1 finger). It was concluded that the bulky 10-strand repair may be used for zone II finger flexor tendon lacerations as long as a profundus-(?) only repair and "venting" of the pulley system are performed.

  16. Bifunctional polydopamine@Fe3O4 core-shell nanoparticles for electrochemical determination of lead(II) and cadmium(II).

    PubMed

    Song, Qian; Li, Maoguo; Huang, Li; Wu, Qikang; Zhou, Yunyou; Wang, Yinling

    2013-07-17

    The present paper has focused on the potential application of the bifunctional polydopamine@Fe3O4 core-shell nanoparticles for development of a simple, stable and highly selective electrochemical method for metal ions monitoring in real samples. The electrochemical method is based on electrochemical preconcentration/reduction of metal ions onto a polydopamine@Fe3O4 modified magnetic glassy carbon electrode at -1.1 V (versus SCE) in 0.1 M pH 5.0 acetate solution containing Pb(2+) and Cd(2+) during 160 s, followed by subsequent anodic stripping. The proposed method has been demonstrated highly selective and sensitive detection of Pb(2+) and Cd(2+), with the calculated detection limits of 1.4×10(-11)M and 9.2×10(-11) M. Under the optimized conditions, the square wave anodic stripping voltammetry response of the modified electrode to Pb(2+) (or Cd(2+)) shows a linear concentration range of 5.0-600 nM (or 20-590 nM) with a correlation coefficient of 0.997 (or 0.994). Further, the proposed method has been performed to successfully detect Pb(2+) and Cd(2+) in aqueous effluent.

  17. Evaluating the accretion of meteoritic debris and interplanetary dust particles in the GPC-3 sediment core using noble gas and mineralogical tracers

    NASA Astrophysics Data System (ADS)

    Darrah, Thomas H.; Poreda, Robert J.

    2012-05-01

    Extraterrestrial (ET) noble gases (helium and neon) in 35 sediment samples from Central Pacific core LL-44 GPC-3 demonstrate the variable flux of interplanetary dust particles (IDPs) and major meteorite impacts over the past 70 Ma (21-72 Ma). Spinel mineralogical and chemical compositions clearly distinguish major impact events from the continuous flux of IDPs, including the well-established Cretaceous/Tertiary (K/T) and late Eocene (E/O) impact boundaries. No spinel grains with chemical or mineralogical evidence of a distinctly ET origin were found in an extensive survey of 'background' samples (i.e. non E/O or K/T boundary) suggesting that either the carrier grains for ET noble gas occur within the Fe-Ti oxide mineral fraction observed in this study (found to include ilmenite and ulvospinel) or are too small for identification by SEM. The presence of ilmenite and ulvospinel suggest lunar regolith is a potential source for ET noble gas-rich particles. Noble gas analysis on both the EMF (extractable magnetic fraction) and the Bulk minus EMF (Bulk - EMF) show that the He and Ne compositions are consistent with partially degassed noble gas signatures of zero-age magnetic grains (Z-MAG) and stratospheric interplanetary dust particles (IDPs). Conclusive evidence for a 'planetary' (Ne-A) noble gas signature is found only in the bulk sediments at the K/T boundary, although all GPC-3 K/T fractions (Bulk, EMF, and HF Digestion) plot along a mixing line between planetary (Ne-A) and solar wind (SW). Spinels from major impact boundaries (K/T; E/O) exhibit dendritic texture and elevated [Ni], consistent with previous reports. In contrast to the otherwise consistent [3He] signal from IDPs, the [3He] at the known impact boundaries (K/T and E/O) actually decreases. These anomalously low [3He] are accompanied by significantly elevated [Ne] and significantly lower (3He/20Ne)solar ratios (˜10× lower) produced by both preferentially degassing of He relative to Ne at times of

  18. γ-Sultam-cored N,N-ligands in the ruthenium(ii)-catalyzed asymmetric transfer hydrogenation of aryl ketones.

    PubMed

    Rast, Slavko; Modec, Barbara; Stephan, Michel; Mohar, Barbara

    2016-02-14

    The synthesis of new enantiopure syn- and anti-3-(α-aminobenzyl)-benzo-γ-sultam ligands 6 and their application in the ruthenium(ii)-catalyzed asymmetric transfer hydrogenation (ATH) of ketones using formic acid/triethylamine is described. In particular, benzo-fused cyclic ketones afforded excellent enantioselectivities in reasonable time employing a low loading of the syn ligand-containing catalyst. A never-before-seen dynamic kinetic resolution (DKR) during reduction of a γ-keto carboxylic ester (S7) derivative of 1-indanone is realized leading as well to excellent induction.

  19. Variation of exciton-vibrational coupling in photosystem II core complexes from Thermosynechococcus elongatus as revealed by single-molecule spectroscopy.

    PubMed

    Skandary, Sepideh; Hussels, Martin; Konrad, Alexander; Renger, Thomas; Müh, Frank; Bommer, Martin; Zouni, Athina; Meixner, Alfred J; Brecht, Marc

    2015-03-19

    The spectral properties and dynamics of the fluorescence emission of photosystem II core complexes are investigated by single-molecule spectroscopy at 1.6 K. The emission spectra are dominated by sharp zero-phonon lines (ZPLs). The sharp ZPLs are the result of weak to intermediate exciton-vibrational coupling and slow spectral diffusion. For several data sets, it is possible to surpass the effect of spectral diffusion by applying a shifting algorithm. The increased signal-to-noise ratio enables us to determine the exciton-vibrational coupling strength (Huang-Rhys factor) with high precision. The Huang-Rhys factors vary between 0.03 and 0.8. The values of the Huang-Rhys factors show no obvious correlation between coupling strength and wavelength position. From this result, we conclude that electrostatic rather than exchange or dispersive interactions are the main contributors to the exciton-vibrational coupling in this system.

  20. LINE PROFILES OF CORES WITHIN CLUSTERS. II. SIGNATURES OF DYNAMICAL COLLAPSE DURING HIGH-MASS STAR FORMATION

    SciTech Connect

    Smith, Rowan J.; Shetty, Rahul; Klessen, Ralf S.; Beuther, Henrik; Bonnell, Ian A.

    2013-07-01

    Observations of atomic or molecular lines can provide important information about the physical state of star-forming regions. In order to investigate the line profiles from dynamical collapsing massive star-forming regions (MSFRs), we model the emission from hydrodynamic simulations of a collapsing cloud in the absence of outflows. By performing radiative transfer calculations, we compute the optically thick HCO{sup +} and optically thin N{sub 2}H{sup +} line profiles from two collapsing regions at different epochs. Due to large-scale collapse, the MSFRs have large velocity gradients, reaching up to 20 km s{sup -1} pc{sup -1} across the central core. The optically thin lines typically contain multiple velocity components resulting from the superposition of numerous density peaks along the line of sight. The optically thick lines are only marginally shifted to the blue side of the optically thin line profiles, and frequently do not have a central depression in their profiles due to self-absorption. As the regions evolve, the lines become brighter and the optically thick lines become broader. The lower-order HCO{sup +} (1-0) transitions are better indicators of collapse than the higher-order (4-3) transitions. We also investigate how the beam sizes affect profile shapes. Smaller beams lead to brighter and narrower lines that are more skewed to the blue in HCO{sup +} relative to the true core velocity, but show multiple components in N{sub 2}H{sup +}. High-resolution observations (e.g., with Atacama Large Millimeter Array) can test these predictions and provide insights into the nature of MSFRs.

  1. The intraflagellar transport protein IFT57 is required for cilia maintenance and regulates IFT-particle-kinesin-II dissociation in vertebrate photoreceptors.

    PubMed

    Krock, Bryan L; Perkins, Brian D

    2008-06-01

    Defects in protein transport within vertebrate photoreceptors can result in photoreceptor degeneration. In developing and mature photoreceptors, proteins targeted to the outer segment are transported through the connecting cilium via the process of intraflagellar transport (IFT). In studies of vertebrate IFT, mutations in any component of the IFT particle typically abolish ciliogenesis, suggesting that IFT proteins are equally required for IFT. To determine whether photoreceptor outer segment formation depends equally on individual IFT proteins, we compared the retinal phenotypes of IFT57 and IFT88 mutant zebrafish. IFT88 mutants failed to form outer segments, whereas IFT57 mutants formed short outer segments with reduced amounts of opsin. Our phenotypic analysis revealed that IFT57 is not essential for IFT, but is required for efficient IFT. In co-immunoprecipitation experiments from whole-animal extracts, we determined that kinesin II remained associated with the IFT particle in the absence of IFT57, but IFT20 did not. Additionally, kinesin II did not exhibit ATP-dependent dissociation from the IFT particle in IFT57 mutants. We conclude that IFT20 requires IFT57 to associate with the IFT particle and that IFT57 and/or IFT20 mediate kinesin II dissociation.

  2. Structure of the catalytic, inorganic core of oxygen-evolving photosystem II at 1.9 Å resolution.

    PubMed

    Kawakami, Keisuke; Umena, Yasufumi; Kamiya, Nobuo; Shen, Jian-Ren

    2011-01-01

    The catalytic center for photosynthetic water-splitting consists of 4 Mn atoms and 1 Ca atom and is located near the lumenal surface of photosystem II. So far the structure of the Mn(4)Ca-cluster has been studied by a variety of techniques including X-ray spectroscopy and diffraction, and various structural models have been proposed. However, its exact structure is still unknown due to the limited resolution of crystal structures of PSII achieved so far, as well as possible radiation damages that might have occurred. Very recently, we have succeeded in solving the structure of photosystem II at 1.9 Å, which yielded a detailed picture of the Mn(4)CaO(5)-cluster for the first time. In the high resolution structure, the Mn(4)CaO(5)-cluster is arranged in a distorted chair form, with a cubane-like structure formed by 3 Mn and 1 Ca, 4 oxygen atoms as the distorted base of the chair, and 1 Mn and 1 oxygen atom outside of the cubane as the back of the chair. In addition, four water molecules were associated with the cluster, among which, two are associated with the terminal Mn atom and two are associated with the Ca atom. Some of these water molecules may therefore serve as the substrates for water-splitting. The high resolution structure of the catalytic center provided a solid basis for elucidation of the mechanism of photosynthetic water splitting. We review here the structural features of the Mn(4)CaO(5)-cluster analyzed at 1.9 Å resolution, and compare them with the structures reported previously.

  3. Safety training and safe operating procedures written for PBFA (Particle Beam Fusion Accelerator) II and applicable to other pulsed power facilities

    SciTech Connect

    Donovan, G.L.; Goldstein, S.A.

    1986-12-01

    To ensure that work in advancing pulsed power technology is performed with an acceptably low risk, pulsed power research facilities at Sandia National Laboratories must satisfy general safety guidelines established by the Department of Energy, policies and formats of the Environment, Safety, and Health (ES and H) Department, and detailed procedures formulated by the Pulsed Power Sciences Directorate. The approach to safety training and to writing safe operating procedures, and the procedures presented here are specific to the Particle Beam Fusion Accelerator II (PBFA II) Facility but are applicable as guidelines to other research and development facilities which have similar hazards.

  4. An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations. Part I: Sea ice and solid freshwater

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Ilicak, Mehmet; Gerdes, Rüdiger; Drange, Helge; Aksenov, Yevgeny; Bailey, David A.; Bentsen, Mats; Biastoch, Arne; Bozec, Alexandra; Böning, Claus; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Curry, Beth; Danabasoglu, Gokhan; Danilov, Sergey; Fernandez, Elodie; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Iovino, Doroteaciro; Jahn, Alexandra; Jung, Thomas; Large, William G.; Lee, Craig; Lique, Camille; Lu, Jianhua; Masina, Simona; Nurser, A. J. George; Rabe, Benjamin; Roth, Christina; Salas y Mélia, David; Samuels, Bonita L.; Spence, Paul; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Xuezhu; Yeager, Steve G.

    2016-03-01

    The Arctic Ocean simulated in fourteen global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE II) is analyzed. The focus is on the Arctic sea ice extent, the solid freshwater (FW) sources and solid freshwater content (FWC). Available observations are used for model evaluation. The variability of sea ice extent and solid FW budget is more consistently reproduced than their mean state in the models. The descending trend of September sea ice extent is well simulated in terms of the model ensemble mean. Models overestimating sea ice thickness tend to underestimate the descending trend of September sea ice extent. The models underestimate the observed sea ice thinning trend by a factor of two. When averaged on decadal time scales, the variation of Arctic solid FWC is contributed by those of both sea ice production and sea ice transport, which are out of phase in time. The solid FWC decreased in the recent decades, caused mainly by the reduction in sea ice thickness. The models did not simulate the acceleration of sea ice thickness decline, leading to an underestimation of solid FWC trend after 2000. The common model behavior, including the tendency to underestimate the trend of sea ice thickness and March sea ice extent, remains to be improved.

  5. Insights into the photoprotective switch of the major light-harvesting complex II (LHCII): a preserved core of arginine-glutamate interlocked helices complemented by adjustable loops.

    PubMed

    Sunku, Kiran; de Groot, Huub J M; Pandit, Anjali

    2013-07-05

    Light-harvesting antennae of the LHC family form transmembrane three-helix bundles of which two helices are interlocked by conserved arginine-glutamate (Arg-Glu) ion pairs that form ligation sites for chlorophylls. The antenna proteins of photosystem II have an intriguing dual function. In excess light, they can switch their conformation from a light-harvesting into a photoprotective state, in which the excess and harmful excitation energies are safely dissipated as heat. Here we applied magic angle spinning NMR and selective Arg isotope enrichment as a noninvasive method to analyze the Arg structures of the major light-harvesting complex II (LHCII). The conformations of the Arg residues that interlock helix A and B appear to be preserved in the light-harvesting and photoprotective state. Several Arg residues have very downfield-shifted proton NMR responses, indicating that they stabilize the complex by strong hydrogen bonds. For the Arg Cα chemical shifts, differences are observed between LHCII in the active, light-harvesting and in the photoprotective, quenched state. These differences are attributed to a conformational change of the Arg residue in the stromal loop region. We conclude that the interlocked helices of LHCII form a rigid core. Consequently, the LHCII conformational switch does not involve changes in A/B helix tilting but likely involves rearrangements of the loops and helical segments close to the stromal and lumenal ends.

  6. Three-dimensional Explosion Geometry of Stripped-envelope Core-collapse Supernovae. II. Modeling of Polarization

    NASA Astrophysics Data System (ADS)

    Tanaka, Masaomi; Maeda, Keiichi; Mazzali, Paolo A.; Kawabata, Koji S.; Nomoto, Ken’ichi

    2017-03-01

    We present modeling of line polarization to study the multidimensional geometry of stripped-envelope core-collapse supernovae (SNe). We demonstrate that a purely axisymmetric, two-dimensional (2D) geometry cannot reproduce a loop in the Stokes Q ‑ U diagram, that is, a variation of the polarization angles along the velocities associated with the absorption lines. On the contrary, three-dimensional (3D) clumpy structures naturally reproduce the loop. The fact that the loop is commonly observed in stripped-envelope SNe suggests that SN ejecta generally have a 3D structure. We study the degree of line polarization as a function of the absorption depth for various 3D clumpy models with different clump sizes and covering factors. A comparison between the calculated and observed degree of line polarization indicates that a typical size of the clump is relatively large, ≳25% of the photospheric radius. Such large-scale clumps are similar to those observed in the SN remnant Cassiopeia A. Given the small size of the observed sample, the covering factor of the clumps is only weakly constrained (∼5%–80%). The presence of a large-scale clumpy structure suggests that the large-scale convection or standing accretion shock instability takes place at the onset of the explosion.

  7. Intra- and inter-nucleosomal interactions of the histone H4 tail revealed with a human nucleosome core particle with genetically-incorporated H4 tetra-acetylation

    PubMed Central

    Wakamori, Masatoshi; Fujii, Yoshifumi; Suka, Noriyuki; Shirouzu, Mikako; Sakamoto, Kensaku; Umehara, Takashi; Yokoyama, Shigeyuki

    2015-01-01

    Post-translational modifications (PTMs) of histones, such as lysine acetylation of the N-terminal tails, play crucial roles in controlling gene expression. Due to the difficulty in reconstituting site-specifically acetylated nucleosomes with crystallization quality, structural analyses of histone acetylation are currently performed using synthesized tail peptides. Through engineering of the genetic code, translation termination, and cell-free protein synthesis, we reconstituted human H4-mono- to tetra-acetylated nucleosome core particles (NCPs), and solved the crystal structures of the H4-K5/K8/K12/K16-tetra-acetylated NCP and unmodified NCP at 2.4 Å and 2.2 Å resolutions, respectively. The structure of the H4-tetra-acetylated NCP resembled that of the unmodified NCP, and the DNA wrapped the histone octamer as precisely as in the unmodified NCP. However, the B-factors were significantly increased for the peripheral DNAs near the N-terminal tail of the intra- or inter-nucleosomal H4. In contrast, the B-factors were negligibly affected by the H4 tetra-acetylation in histone core residues, including those composing the acidic patch, and at H4-R23, which interacts with the acidic patch of the neighboring NCP. The present study revealed that the H4 tetra-acetylation impairs NCP self-association by changing the interactions of the H4 tail with DNA, and is the first demonstration of crystallization quality NCPs reconstituted with genuine PTMs. PMID:26607036

  8. Hepatitis B virus-like particles access major histocompatibility class I and II antigen presentation pathways in primary dendritic cells.

    PubMed

    Moffat, Jessica M; Cheong, Wan-Shoo; Villadangos, José A; Mintern, Justine D; Netter, Hans J

    2013-04-26

    Virus-like particles (VLPs) represent high density displays of viral proteins that efficiently trigger immunity. VLPs composed of the small hepatitis B virus envelope protein (HBsAgS) are useful vaccine platforms that induce humoral and cellular immune responses. Notably, however, some studies suggest HBsAgS VLPs impair dendritic cell (DC) function. Here we investigated HBsAgS VLP interaction with DC subsets and antigen access to major histocompatibility complex (MHC) class I and II antigen presentation pathways in primary DCs. HBsAgS VLPs impaired plasmacytoid DC (pDC) interferon alpha (IFNα) production in response to CpG in vitro, but did not alter conventional DC (cDC) or pDC phenotype when administered in vivo. To assess cellular immune responses, HBsAgS VLPs were generated containing the ovalbumin (OVA) model epitopes OVA(257-264) and OVA(323-339) to access MHCI and MHCII antigen presentation pathways, respectively; both in vitro and following immunisation in vivo. HBsAgS VLP-OVA(257-264) elicited CTL responses in vivo that were not enhanced by inclusion of an additional MHCII helper epitope. HBsAgS VLP-OVA(257-264) administered in vivo was cross-presented by CD8(+) DCs, but not CD8(-) DCs. Therefore, HBsAgS VLPs can deliver antigen to both MHCI and MHCII antigen presentation pathways in primary DCs and promote cytotoxic and helper T cell priming despite their suppressive effect on pDCs.

  9. Calcium controls the assembly of the photosynthetic water-oxidizing complex: a cadmium(II) inorganic mutant of the Mn4Ca core.

    PubMed

    Bartlett, John E; Baranov, Sergei V; Ananyev, Gennady M; Dismukes, G Charles

    2008-03-27

    Perturbation of the catalytic inorganic core (Mn4Ca1OxCly) of the photosystem II-water-oxidizing complex (PSII-WOC) isolated from spinach is examined by substitution of Ca2+ with cadmium(II) during core assembly. Cd2+ inhibits the yield of reconstitution of O2-evolution activity, called photoactivation, starting from the free inorganic cofactors and the cofactor-depleted apo-WOC-PSII complex. Ca2+ affinity increases following photooxidation of the first Mn2+ to Mn3+ bound to the 'high-affinity' site. Ca2+ binding occurs in the dark and is the slowest overall step of photoactivation (IM1-->IM1* step). Cd2+ competitively blocks the binding of Ca2+ to its functional site with 10- to 30-fold higher affinity, but does not influence the binding of Mn2+ to its high-affinity site. By contrast, even 10-fold higher concentrations of Cd2+ have no effect on O2-evolution activity in intact PSII-WOC. Paradoxically, Cd2+ both inhibits photoactivation yield, while accelerating the rate of photoassembly of active centres 10-fold relative to Ca2+. Cd2+ increases the kinetic stability of the photooxidized Mn3+ assembly intermediate(s) by twofold (mean lifetime for dark decay). The rate data provide evidence that Cd2+ binding following photooxidation of the first Mn3+, IM1-->IM1*, causes three outcomes: (i) a longer intermediate lifetime that slows IM1 decay to IM0 by charge recombination, (ii) 10-fold higher probability of attaining the degrees of freedom (either or both cofactor and protein d.f.) needed to bind and photooxidize the remaining 3 Mn2+ that form the functional cluster, and (iii) increased lability of Cd2+ following Mn4 cluster assembly results in (re)exchange of Cd2+ by Ca2+ which restores active O2-evolving centres. Prior EPR spectroscopic data provide evidence for an oxo-bridged assembly intermediate, Mn3+(mu-O2(-))Ca2+, for IM1*. We postulate an analogous inhibited intermediate with Cd2+ replacing Ca2+.

  10. Method of determining nanoparticle core weight.

    PubMed

    Reynolds, Fred; O'loughlin, Terry; Weissleder, Ralph; Josephson, Lee

    2005-02-01

    Polymer-coated metal or metal oxide nanoparticles have a variety of uses in industry, biological research, and medicine. Characterization of nanoparticles often includes determination of the dimensions of the electron-dense core by transmission electron microscopy (TEM), with the weight of the core determined from core volume and core density. However, TEM is labor intensive, has a long turnaround time, and uses equipment that is sometimes not readily available. Here we present an alternative method for determining the weight of nanoparticle cores termed the viscosity/light scattering method, which uses (i) measurements of viscosity over a wide concentration range to obtain the partial specific volume, (ii) measurements of particle diameter by light scattering, to obtain the volume of an individual particle, and (iii) the concentration of nanoparticles (w/v). We have applied this method to determine the weights of nanoparticle cores (iron of amino-CLIO and ferritin), the weights of globular proteins (molecular weight of IgG and albumin), and the weight of polystyrene microspheres. The viscosity/light scattering method is nondestructive of the sample and can be performed with a variety of materials on a routine basis.

  11. Airborne Single Particle Mass Spectrometers (SPLAT II & miniSPLAT) and New Software for Data Visualization and Analysis in a Geo-Spatial Context

    NASA Astrophysics Data System (ADS)

    Zelenyuk, Alla; Imre, Dan; Wilson, Jacqueline; Zhang, Zhiyuan; Wang, Jun; Mueller, Klaus

    2015-02-01

    Understanding the effect of aerosols on climate requires knowledge of the size and chemical composition of individual aerosol particles—two fundamental properties that determine an aerosol's optical properties and ability to serve as cloud condensation or ice nuclei. Here we present our aircraft-compatible single particle mass spectrometers, SPLAT II and its new, miniaturized version, miniSPLAT that measure in-situ and in real-time the size and chemical composition of individual aerosol particles with extremely high sensitivity, temporal resolution, and sizing precision on the order of a monolayer. Although miniSPLAT's size, weight, and power consumption are significantly smaller, its performance is on par with SPLAT II. Both instruments operate in dual data acquisition mode to measure, in addition to single particle size and composition, particle number concentrations, size distributions, density, and asphericity with high temporal resolution. We also present ND-Scope, our newly developed interactive visual analytics software package. ND-Scope is designed to explore and visualize the vast amount of complex, multidimensional data acquired by our single particle mass spectrometers, along with other aerosol and cloud characterization instruments on-board aircraft. We demonstrate that ND-Scope makes it possible to visualize the relationships between different observables and to view the data in a geo-spatial context, using the interactive and fully coupled Google Earth and Parallel Coordinates displays. Here we illustrate the utility of ND-Scope to visualize the spatial distribution of atmospheric particles of different compositions, and explore the relationship between individual particle compositions and their activity as cloud condensation nuclei.

  12. Magnetic C-C@Fe3O4 double-shelled hollow microspheres via aerosol-based Fe3O4@C-SiO2 core-shell particles.

    PubMed

    Zhu, Yangzhi; Li, Xiangcun; He, Gaohong; Qi, Xinhong

    2015-02-18

    Magnetic C-C@Fe3O4 hollow microspheres were prepared by using aerosol-based Fe3O4@C-SiO2 core-shell particles as templates. The magnetic double-shelled microspheres efficiently worked as carriers to load Pt nanoparticles, thus making the catalyst recyclable and reusable.

  13. NACRE II: an update of the NACRE compilation of charged-particle-induced thermonuclear reaction rates for nuclei with mass number A<16

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Takahashi, K.; Goriely, S.; Arnould, M.; Ohta, M.; Utsunomiya, H.

    2013-11-01

    An update of the NACRE compilation [3] is presented. This new compilation, referred to as NACRE II, reports thermonuclear reaction rates for 34 charged-particle induced, two-body exoergic reactions on nuclides with mass number A<16, of which fifteen are particle-transfer reactions and the rest radiative capture reactions. When compared with NACRE, NACRE II features in particular (1) the addition to the experimental data collected in NACRE of those reported later, preferentially in the major journals of the field by early 2013, and (2) the adoption of potential models as the primary tool for extrapolation to very low energies of astrophysical S-factors, with a systematic evaluation of uncertainties.

  14. Steric stabilization of nonaqueous silicon slips. I - Control of particle agglomeration and packing. II - Pressure casting of powder compacts

    NASA Technical Reports Server (NTRS)

    Kerkar, Awdhoot V.; Henderson, Robert J. M.; Feke, Donald L.

    1990-01-01

    The application of steric stabilization to control particle agglomeration and packing of silicon powder in benzene and trichloroethylene is reported. The results provide useful guidelines for controlling unfavorable particle-particle interactions during nonaqueous processing of silicon-based ceramic materials. The application of steric stabilization to the control and improvement of green processing of nonaqueous silicon slips in pressure consolidation is also demonstrated.

  15. Cosmic ray heating in cool core clusters II: Self-regulation cycle and non-thermal emission

    NASA Astrophysics Data System (ADS)

    Jacob, Svenja; Pfrommer, Christoph

    2017-01-01

    Self-regulated feedback by active galactic nuclei (AGNs) appears to be critical in balancing radiative cooling of the low-entropy gas at the centres of galaxy clusters and in regulating star formation in central galaxies. In a companion paper, we found steady state solutions of the hydrodynamic equations that are coupled to the CR energy equation for a large cluster sample. In those solutions, radiative cooling in the central region is balanced by streaming CRs through the generation and dissipation of resonantly generated Alfvén waves and by thermal conduction at large radii. Here we demonstrate that the predicted non-thermal emission resulting from hadronic CR interactions in the intra-cluster medium exceeds observational radio (and gamma-ray) data in a subsample of clusters that host radio mini halos (RMHs). In contrast, the predicted non-thermal emission is well below observational data in cooling galaxy clusters without RMHs. These are characterised by exceptionally large AGN radio fluxes, indicating high CR yields and associated CR heating rates. We suggest a self-regulation cycle of AGN feedback in which non-RMH clusters are heated by streaming CRs homogeneously throughout the central cooling region. We predict radio micro halos surrounding the AGNs of these CR-heated clusters in which the primary emission may predominate the hadronically generated emission. Once the CR population has streamed sufficiently far and lost enough energy, the cooling rate increases, which explains the increased star formation rates in clusters hosting RMHs. Those could be powered hadronically by CRs that have previously heated the cluster core.

  16. Rubber particles from four different species, examined by transmission electron microscopy and electron-paramagnetic-resonance spin labeling, are found to consist of a homogeneous rubber core enclosed by a contiguous, monolayer biomembrane

    PubMed

    Cornish; Wood; Windle

    1999-11-01

    The physical characteristics of rubber particles from the four rubber (cis-1,4-polyisoprene) producing species Euphorbia lactiflua Phil., Ficus elastica Roxb., Hevea brasiliensis Mull. Arg., and Parthenium argentatum Gray, were investigated using transmission electron microscopy (TEM) and electron-paramagnetic-resonance (EPR) spin labeling spectroscopy. Transmission electron microscopy showed the rubber particles to be composed of a spherical, homogeneous, core of rubber enclosed by a contiguous, electron-dense, single-track surface layer. The biochemical composition of the surface layer and its single-track TEM suggested that a monolayer biomembrane was the surface structure most compatible with the hydrophobic rubber core. The EPR spectra for a series of positional isomers of doxyl stearic acid, used to label the surface layer of the rubber particles, exhibited flexibility gradients and evidence for lipid-protein interactions for all four rubber particle types that is consistent with a biomembrane-like surface. The EPR spectra confirmed that the surface biomembrane is a monolayer. Thus, rubber particles appear similar to oil bodies in their basic architecture. The EPR spectra also provided information on protein location and degree of biomembrane penetration that correlated with the known properties of the rubber-particle-bound proteins. The monolayer biomembrane serves as an interface between the hydrophobic rubber interior and the aqueous cytosol and prevents aggregation of the particles. An unexpected observation for the probes in pure polyisoprene was evidence of an intrinsic flexibility gradient associated with the stearic acid molecule itself.

  17. A Thiophene-Containing Conductive Metallopolymer Using an Fe(II) Bis(terpyridine) Core for Electrochromic Materials.

    PubMed

    Liang, Yawei; Strohecker, Daniel; Lynch, Vincent; Holliday, Bradley J; Jones, Richard A

    2016-12-21

    Three Fe(II) bis(terpyridine)-based complexes with thiophene (Fe(L1)2), bithiophene (Fe(L2)2), and 3,4-ethylenedioxythiophene (Fe(L3)2) side chains were designed and synthesized for the purpose of providing two terminal active sites for electrochemical polymerization. The corresponding metallopolymers (poly-Fe(Ln)2, n = 2 or 3) were synthesized on indium tin oxide (ITO)-coated glass substrates via oxidative electropolymerization of the thiophene-substituted monomers and characterized using electrochemistry, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and atomic force microscopy. The film poly-Fe(L2)2 was further studied for electrochromic (EC) color-switching properties and fabricated into a solid-state EC device. Poly-Fe(L2)2 films exhibit an intense MLCT absorption band at 596 nm (ε = 4.7 × 10(4) M(-1) cm(-1)) in the UV-vis spectra without any applied voltage. Upon application of low potentials (between 1.1 and 0.4 V vs Fc(+)/Fc), the obtained electropolymerized film exhibited great contrast with a change of transmittance percentage (ΔT%) of 40% and a high coloration efficiency of 3823 cm(2) C(-1) with a switching time of 1 s. The film demonstrates commonplace stability and reversibility with a 10% loss in peak current intensity after 200 cyclic voltammetry cycles and almost no loss in change of transmittance (ΔT%) after 900 potential switches between 1.1 and 0.4 V (vs Fc(+)/Fc) with a time interval of 0.75 s. The electropolymerization of Fe(L2)2 provides convenient and controllable film fabrication. Electrochromic behavior was also achieved in a solid-state device composed of a poly-Fe(L2)2 film and a polymer-supported electrolyte sandwiched between two ITO-coated glass electrodes.

  18. PHYSALIS: a new method for particle simulation. Part II: two-dimensional Navier-Stokes flow around cylinders

    NASA Astrophysics Data System (ADS)

    Takagi, S.; Og˜uz, H. N.; Zhang, Z.; Prosperetti, A.

    2003-05-01

    This paper presents a new approach to the direct numerical simulation of particle flows. The basic idea is to use a local analytic representation valid near the particle to "transfer" the no-slip condition from the particle surface to the adjacent grid nodes. In this way the geometric complexity arising from the irregular relation between the particle boundary and the underlying mesh is avoided and fast solvers can be used. The results suggest that the computational effort increases very slowly with the number of particles so that the method is efficient for large-scale simulations. The focus here is on the two-dimensional case (cylindrical particles), but the same procedure, to be developed in forthcoming papers, applies to three dimensions (spherical particles). Several extensions are briefly discussed.

  19. Virus-like particles of hepatitis B virus core protein containing five mimotopes of infectious bursal disease virus (IBDV) protect chickens against IBDV.

    PubMed

    Wang, Yong-shan; Ouyang, Wei; Liu, Xiao-juan; He, Kong-wang; Yu, Sheng-qing; Zhang, Hai-bin; Fan, Hong-jie; Lu, Cheng-ping

    2012-03-09

    Current infectious bursal disease virus (IBDV) vaccines suffer from maternal antibody interference and mimotope vaccines might be an alternative. Previously we demonstrated an IBDV VP2 five-mimotope polypeptide, 5EPIS, elicited protective immunity in chickens. In the current study, the 5epis gene was inserted into a plasmid carrying human hepatitis B virus core protein (HBc) gene at its major immunodominant region site. The recombinant gene was efficiently expressed in Escherichia coli to produce chimeric protein HBc-5EPIS which self-assembles to virus-like particles (VLP). Two-week old specific-pathogen-free chickens were immunized intramuscularly with HBc-5EPIS VLP or 5EPIS polypeptide without adjuvant (50 μg/injection) on day 0, 7, 14 and 21. Anti-5EPIS antibody was first detected on day 7 and day 21 in HBc-5EPIS and 5EPIS groups, respectively; on day 28, anti-5EPIS titers reached 12,800 or 1600 by ELISA, and 3200 or 800 by virus neutralization assay in HBc-5EPIS and 5EPIS groups, respectively. No anti-5EPIS antibody was detected in the buffer control group throughout the experiment. Challenge on day 28 with a virulent IBDV strain (GX8/99) resulted in 100%, 40.0% and 26.7% survival for chickens immunized with HBc-5EPIS, 5EPIS and buffer, respectively. These data suggest epitope presentation on chimeric VLP is a promising approach for improving mimotope vaccines for IBDV.

  20. Chemical cross-linking, mass spectrometry and in silico modeling of proteasomal 20S core particles of the haloarchaeon Haloferax volcanii

    PubMed Central

    Karadzic, Ivanka; Maupin-Furlow, Julie; Humbard, Matt; Prunetti, Laurence; Singh, Pragya; Goodlett, David R.

    2012-01-01

    A fast and accurate method is reported to generate distance constraints between juxtaposited amino acids and to validate molecular models of halophilic protein complexes. Proteasomal 20S core particles (CPs) from the haloarchaeon Haloferax volcanii were used to investigate the quaternary structure of halophilic proteins based on their symmetrical, yet distinct subunit composition. Proteasomal CPs are cylindrial barrel-like structures of four-stacked homoheptameric rings of α- and β-type subunits organized in α7β7β7α7 stoichiometry. The CPs of H. volcanii are formed from a single type of β subunit associated with α1 and/or α2 subunits. Tandem affinity chromatography and new genetic constructs were used to separately isolate α17β7β7α17 and α27β7β7α27 CPs from H. volcanii. Chemically cross-linked peptides of the H. volcanii CPs were analyzed by high-performance mass spectrometry and an open modification search strategy to first generate and then to interpret the resulting tandem mass spectrometric data. Distance constraints obtained by chemical cross-linking mass spectrometry (CXMS), together with the available structural data of non-halophilic CPs, facilitated the selection of accurate models of H. volcanii proteasomal CPs composed of α1-, α2-, and β-homoheptameric rings from among several different possiblePDB structures. PMID:22623373

  1. A novel virus-like particle based on hepatitis B core antigen and substrate-binding domain of bacterial molecular chaperone DnaK.

    PubMed

    Wang, Xue Jun; Gu, Kai; Xiong, Qi Yan; Shen, Liang; Cao, Rong Yue; Li, Ming Hui; Li, Tai Ming; Wu, Jie; Liu, Jing Jing

    2009-12-09

    Hepatitis B virus core (HBc) protein has been proved to be an attractive carrier for foreign epitopes, and can display green fluorescent protein (GFP) on its surface. The structure of substrate-binding domain of DnaK [DnaK (394-504 aa), DnaK SBD] is similar to GFP, we therefore reasoned that DnaK SBD might also be tolerated. Electron microscopic observations suggested that the chimeric proteins containing the truncated HBc (HBcDelta) and DnaK SBD could self-assemble into virus-like particle (VLP). Then the accessibility of DnaK SBD and the adjuvanticity of VLP HBcDelta-SBD were demonstrated by two recombinant peptide vaccines against gonadotropin-releasing hormone (GnRH), GhM and GhMNR. The latter carries in addition the peptide motif NRLLLTG which is known to bind to DnaK and DnaK SBD. The combination of VLP HBcDelta-SBD and GhMNR elicited stronger humoral responses and caused further testicular atrophy than the combinations of VLP HBcDelta and GhMNR or VLP HBcDelta-SBD and GhM in Balb/c mice. These findings indicate VLP HBcDelta-SBD might serve as an excellent carrier for GhMNR and some other peptide vaccines.

  2. The t-J model of hard-core bosons in slave-particle representation and its Monte-Carlo simulations

    NASA Astrophysics Data System (ADS)

    Nakano, Yuki; Ishima, Takumi; Kobayashi, Naohiro; Sakakibara, Kazuhiko; Ichinose, Ikuo; Matsui, Tetsuo

    2012-12-01

    We study the system of hard-core bosons (HCB) with two species in the three-dimensional lattice at finite temperatures. In the strong-correlation limit, the system becomes the bosonic t-J model, that is, the t-J model of “bosonic electrons”. The bosonic “electron” operator Bxσ at the site x with a two-component spin σ(= 1, 2***) is treated as a HCB operator, and represented by a composite of two slave particles; a spinon described by a Schwinger boson (CP1 boson) zxσ and a holon described by a HCB field φx as Bxσ = φ†xzxσ.*** This φx is again represented by another CP1 quasi-spinon operator ωxa*** (a = 1, 2***). The phase diagrams of the resulting double CP1 system obtained by Monte Carlo simulations involve first-order and second-order phase boundaries. We present in detail the techniques and algorithm to reduce the hysteresis and locate the first-order transition points.

  3. Construction, expression and immunogenicity of a novel anti-hypertension angiotensin II vaccine based on hepatitis A virus-like particle.

    PubMed

    Ou, Xia; Guo, Lili; Wu, Jinyuan; Mi, Kai; Yin, Na; Zhang, Guangming; Li, Hongjun; Sun, Maosheng

    2013-06-01

    Hypertension is a serious worldwide public health problem. The aim of this study is to design anti-hypertension angiotensin II (Ang II) vaccine using molecular biology and immunological method. This novel anti-hypertension vaccine, which is a chimeric protein named pHAV-4Ang IIs, presents four successive repeated Ang IIs as the functional epitope on the surface of the hepatitis A virus-like particle(HAVLP). In this study, pHAV-4Ang IIs was expressed using Bac-to-Bac Baculovirus Expression System. With the RT-PCR analysis, SDS-PAGE, western blot, IFA, electron microscope methods for identification of expression products, these results confirmed that stable expression of pHAV-4Ang IIs can be effectively achieved in infected sf9 cells. Spontaneous hypertensive rats (SHRs) were immunized with pHAV-4Ang IIs to test immunogenicity and pharmacodynamic action. The results showed that this anti-hypertension vaccine can induce high titer Ang II -specific IgG antibody for almost 10 weeks. When antibody titer reached the peak at 8th week, the mean systolic blood pressure (SBP) degraded approximately 23 mmHg compared with the PBS control group, and the mean diastolic blood pressure (DBP) degraded approximately 12 mmHg compared with the PBS control group. These results suggest that this anti-hypertension vaccine has good immunogenicity and good effect on reduction of blood pressure in SHRs, which provide reliable base for large-scale preparation of this hypertension vaccine in the future, and a new direction of exploration for the development of anti-hypertension therapeutic vaccine.

  4. Temperature Dependence of Light-Induced Absorbance Changes Associated with Chlorophyll Photooxidation in Manganese-Depleted Core Complexes of Photosystem II.

    PubMed

    Zabelin, A A; Shkuropatova, V A; Shkuropatov, A Ya; Shuvalov, V A

    2015-10-01

    Mid-infrared (4500-1150 cm(-1)) absorbance changes induced by continuous illumination of Mn-depleted core complexes of photosystem II (PSII) from spinach in the presence of exogenous electron acceptors (potassium ferricyanide and silicomolybdate) were studied by FTIR difference spectroscopy in the temperature range 100-265 K. The FTIR difference spectrum for photooxidation of the chlorophyll dimer P680 was determined from the set of signals associated with oxidation of secondary electron donors (β-carotene, chlorophyll) and reduction of the primary quinone QA. On the basis of analysis of the temperature dependence of the P680(+)/P680 FTIR spectrum, it was concluded that frequencies of 13(1)-keto-C=O stretching modes of neutral chlorophyll molecules PD1 and PD2, which constitute P680, are similar to each other, being located at ~1700 cm(-1). This together with considerable difference between the stretching mode frequencies of keto groups of PD1(+) and PD2(+) cations (1724 and 1709 cm(-1), respectively) is in agreement with a literature model (Okubo et al. (2007) Biochemistry, 46, 4390-4397) suggesting that the positive charge in the P680(+) dimer is mainly localized on one of the two chlorophyll molecules. A partial delocalization of the charge between the PD1 and PD2 molecules in P680(+) is supported by the presence of a characteristic electronic intervalence band at ~3000 cm(-1). It is shown that a bleaching band at 1680 cm(-1) in the P680(+)/P680 FTIR spectrum does not belong to P680. A possible origin of this band is discussed, taking into account the temperature dependence (100-265 K) of light-induced absorbance changes of PSII core complexes in the visible spectral region from 620 to 720 nm.

  5. Airborne Single Particle Mass Spectrometers (SPLAT II & miniSPLAT) and New Software for Data Visualization and Analysis in a Geo-Spatial Context

    SciTech Connect

    Zelenyuk, Alla; Imre, D.; Wilson, Jacqueline M.; Zhang, Zhiyuan; Wang, Jun; Mueller, Klaus

    2015-02-01

    Understanding the effect of aerosols on climate requires knowledge of the size and chemical composition of individual aerosol particles - two fundamental properties that determine an aerosol’s optical properties and ability to serve as cloud condensation or ice nuclei. Here we present miniSPLAT, our new aircraft compatible single particle mass spectrometer, that measures in-situ and in real-time size and chemical composition of individual aerosol particles with extremely high sensitivity, temporal resolution, and sizing precision on the order of a monolayer. miniSPLAT operates in dual data acquisition mode to measure, in addition to single particle size and composition, particle number concentrations, size distributions, density, and asphericity with high temporal resolution. When compared to our previous instrument, SPLAT II, miniSPLAT has been significantly reduced in size, weight, and power consumption without loss in performance. We also present ND-Scope, our newly developed interactive visual analytics software package. ND-Scope is designed to explore and visualize the vast amount of complex, multidimensional data acquired by our single particle mass spectrometers, along with other aerosol and cloud characterization instruments on-board aircraft. We demonstrate that ND-Scope makes it possible to visualize the relationships between different observables and to view the data in a geo-spatial context, using the interactive and fully coupled Google Earth and Parallel Coordinates displays. Here we illustrate the utility of ND-Scope to visualize the spatial distribution of atmospheric particles of different compositions, and explore the relationship between individual particle composition and their activity as cloud condensation nuclei.

  6. Phase II studies to select the formulation of a multivalent HPV L1 virus-like particle (VLP) vaccine

    PubMed Central

    Luxembourg, Alain; Brown, Darron; Bouchard, Celine; Giuliano, Anna R; Iversen, Ole-Erik; Joura, Elmar A; Penny, Mary E; Restrepo, Jaime A; Romaguera, Josefina; Maansson, Roger; Moeller, Erin; Ritter, Michael; Chen, Joshua

    2015-01-01

    Our objective was to develop a multivalent prophylactic HPV vaccine that protects against infection and disease caused by HPV16/18 (oncogenic types in existing prophylactic vaccines) plus additional oncogenic types by conducting 3 Phase II studies comparing the immunogenicity (i.e., anti-HPV6/11/16/18 geometric mean titers [GMT]) and safety of 7 vaccine candidates with the licensed quadrivalent HPV6/11/16/18 vaccine (qHPV vaccine) in young women ages 16–26. In the first study (Study 1), subjects received one of 3 dose formulations of an 8-valent HPV6/11/16/18/31/45/52/58 vaccine or qHPV vaccine (control). In Study 2, subjects received one of 3 dose formulations (termed low-, mid-, and high-dose formulations, respectively) of a 9-valent HPV6/11/16/18/31/33/45/52/58 vaccine (9vHPV vaccine) or qHPV vaccine (control). In Study 3, subjects concomitantly received qHPV vaccine plus 5-valent HPV31/33/45/52/58 or qHPV vaccine plus placebo (control). All vaccines were administered at day 1/month 2/month 6. In studies 1 and 3, anti-HPV6/11/16/18 GMTs at month 7 were non-inferior in the experimental arms compared with the control arm; however, there was a trend for lower antibody responses for all 4 HPV types. In Study 2, this immune interference was overcome with the mid- and high-dose formulations of the 9vHPV vaccine by increasing antigen and adjuvant doses. In all 3 studies, all vaccine candidates were strongly immunogenic with respect to HPV31/33/45/52/58 and were well tolerated. Based on the totality of the results, the middle dose formulation of the 9vHPV vaccine was selected for Phase III evaluation. Each 0.5mL dose contains 30μg/40μg/60μg/40μg/20μg/20μg/20μg/20μg/20μg of HPV6/11/16/18/31/33/45/52/58 virus-like particles, and 500μg of amorphous aluminum hydroxyphosphate sulfate adjuvant.ClinicalTrials.gov numbers NCT00260039, NCT00543543, and NCT00551187. PMID:25912208

  7. Phase II studies to select the formulation of a multivalent HPV L1 virus-like particle (VLP) vaccine.

    PubMed

    Luxembourg, Alain; Brown, Darron; Bouchard, Celine; Giuliano, Anna R; Iversen, Ole-Erik; Joura, Elmar A; Penny, Mary E; Restrepo, Jaime A; Romaguera, Josefina; Maansson, Roger; Moeller, Erin; Ritter, Michael; Chen, Joshua

    2015-01-01

    Our objective was to develop a multivalent prophylactic HPV vaccine that protects against infection and disease caused by HPV16/18 (oncogenic types in existing prophylactic vaccines) plus additional oncogenic types by conducting 3 Phase II studies comparing the immunogenicity (i.e., anti-HPV6/11/16/18 geometric mean titers [GMT]) and safety of 7 vaccine candidates with the licensed quadrivalent HPV6/11/16/18 vaccine (qHPV vaccine) in young women ages 16-26. In the first study (Study 1), subjects received one of 3 dose formulations of an 8-valent HPV6/11/16/18/31/45/52/58 vaccine or qHPV vaccine (control). In Study 2, subjects received one of 3 dose formulations (termed low-, mid-, and high-dose formulations, respectively) of a 9-valent HPV6/11/16/18/31/33/45/52/58 vaccine (9vHPV vaccine) or qHPV vaccine (control). In Study 3, subjects concomitantly received qHPV vaccine plus 5-valent HPV31/33/45/52/58 or qHPV vaccine plus placebo (control). All vaccines were administered at day 1/month 2/month 6. In studies 1 and 3, anti-HPV6/11/16/18 GMTs at month 7 were non-inferior in the experimental arms compared with the control arm; however, there was a trend for lower antibody responses for all 4 HPV types. In Study 2, this immune interference was overcome with the mid- and high-dose formulations of the 9vHPV vaccine by increasing antigen and adjuvant doses. In all 3 studies, all vaccine candidates were strongly immunogenic with respect to HPV31/33/45/52/58 and were well tolerated. Based on the totality of the results, the middle dose formulation of the 9vHPV vaccine was selected for Phase III evaluation. Each 0.5mL dose contains 30μg/40μg/60μg/40μg/20μg/20μg/20μg/20μg/20μg of HPV6/11/16/18/31/33/45/52/58 virus-like particles, and 500μg of amorphous aluminum hydroxyphosphate sulfate adjuvant.ClinicalTrials.gov numbers NCT00260039, NCT00543543, and NCT00551187.

  8. An assessment of Antarctic Circumpolar Current and Southern Ocean meridional overturning circulation during 1958-2007 in a suite of interannual CORE-II simulations

    NASA Astrophysics Data System (ADS)

    Farneti, Riccardo; Downes, Stephanie M.; Griffies, Stephen M.; Marsland, Simon J.; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Böning, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Chassignet, Eric; Danabasoglu, Gokhan; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Fogli, Pier Giuseppe; Gusev, Anatoly; Hallberg, Robert W.; Howard, Armando; Ilicak, Mehmet; Jung, Thomas; Kelley, Maxwell; Large, William G.; Leboissetier, Anthony; Long, Matthew; Lu, Jianhua; Masina, Simona; Mishra, Akhilesh; Navarra, Antonio; George Nurser, A. J.; Patara, Lavinia; Samuels, Bonita L.; Sidorenko, Dmitry; Tsujino, Hiroyuki; Uotila, Petteri; Wang, Qiang; Yeager, Steve G.

    2015-09-01

    In the framework of the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II), we present an analysis of the representation of the Antarctic Circumpolar Current (ACC) and Southern Ocean meridional overturning circulation (MOC) in a suite of seventeen global ocean-sea ice models. We focus on the mean, variability and trends of both the ACC and MOC over the 1958-2007 period, and discuss their relationship with the surface forcing. We aim to quantify the degree of eddy saturation and eddy compensation in the models participating in CORE-II, and compare our results with available observations, previous fine-resolution numerical studies and theoretical constraints. Most models show weak ACC transport sensitivity to changes in forcing during the past five decades, and they can be considered to be in an eddy saturated regime. Larger contrasts arise when considering MOC trends, with a majority of models exhibiting significant strengthening of the MOC during the late 20th and early 21st century. Only a few models show a relatively small sensitivity to forcing changes, responding with an intensified eddy-induced circulation that provides some degree of eddy compensation, while still showing considerable decadal trends. Both ACC and MOC interannual variabilities are largely controlled by the Southern Annular Mode (SAM). Based on these results, models are clustered into two groups. Models with constant or two-dimensional (horizontal) specification of the eddy-induced advection coefficient κ show larger ocean interior decadal trends, larger ACC transport decadal trends and no eddy compensation in the MOC. Eddy-permitting models or models with a three-dimensional time varying κ show smaller changes in isopycnal slopes and associated ACC trends, and partial eddy compensation. As previously argued, a constant in time or space κ is responsible for a poor representation of mesoscale eddy effects and cannot properly simulate the sensitivity of the ACC and MOC

  9. Ultrasonic synthesis of two new zinc(II) bipyridine coordination polymers: New precursors for preparation of zinc(II) oxide nano-particles.

    PubMed

    Fard, Mohammad Jaafar Soltanian; Hayati, Payam; Firoozadeh, Azita; Janczak, Jan

    2017-03-01

    Nanoparticles of two zinc(II) coordination polymers (CPs), [Zn(μ-4,4'-bipy)Cl2]n (1) and [Zn(μ-4,4'-bipy)Br2]n (2) L=bpy=4,4'-bipyridine ligand, have been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compounds 1 and 2 imply that the Zn(+2) ions are four coordinated. Topological analysis shows that 1D coordination networks of 1 and 2 can be classified as underlying nets of topological types 2C1. Nanoparticles of zinc(II) oxide have been prepared by calcination of two different zinc (II) CPs at 450°C that were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and IR spectroscopy.

  10. Health effects of acute exposure to air polllution. Part II: Healthy subjects exposed to cencentrated ambient particles

    EPA Science Inventory

    The purpose of this study was to assess the impact of short-term exposure to concentrated ambient particles (CAPs*) on lung function and on inflammatory parameters in blood and airways of healthy human subjects. Particles were concentrated from the ambient air in Chapel Hill, Nor...

  11. Single-molecule magnet behavior in heterometallic M(II)-Mn(III)(2)-M(II) tetramers (M(II) = Cu, Ni) containing Mn(III) salen-type dinuclear core.

    PubMed

    Kachi-Terajima, Chihiro; Miyasaka, Hitoshi; Saitoh, Ayumi; Shirakawa, Naoki; Yamashita, Masahiro; Clérac, Rodolphe

    2007-07-23

    The linear-type heterometallic tetramers, [Mn(III)(2)(5-MeOsaltmen)(2)M(II)(2)(L)(2)](CF(3)SO(3))(2) x 2H(2)O (MII = Cu, 1a; Ni, 2a), where 5-MeOsaltmen(2-) = N,N'-(1,1,2,2-tetramethylethylene) bis(5-methoxysalicylideneiminate), and H(2)L = 3-{2-[(2-hydroxy-benzylidene)-amino]-2-methyl-propylimino}-butan-2-one oxime, have been synthesized and characterized from structural and magnetic points of view. These two compounds are isostructural and crystallize in the same monoclinic P2(1)/n space group. The structure has a [M(II)-NO-Mn(III)-(O)(2)-Mn(III)-ON-M(II)] skeleton, where -NO- is a linking oximato group derived from the non-symmetrical Schiff-base complex [M(II)(L)] and -(O)(2)- is a biphenolato bridge in the out-of-plane [Mn(2)(5-MeOsaltmen)(2)](2+) dimer. The solvent-free compounds, 1b and 2b, have also been prepared by drying of the parent compounds, 1a and 2a, respectively, at 100 degrees C under dried nitrogen. After this treatment, the crystallinity is preserved, and 1b and 2b crystallize in a monoclinic P2(1)/c space group without significant changes in their structures in comparison to 1a and 2a. Magnetic measurements on 1a and 1b revealed antiferromagnetic Mn(III)---Cu(II) interactions via the oximato group and weak ferromagnetic Mn(III)---Mn(III) interactions via the biphenolato bridge leading to an S(T) = 3 ground state. On the other hand, the diamagnetic nature of the square planar Ni(II) center generates an S(T) = 4 ground state for 2a and 2b. At low temperature, these solvated (a) and desolvated (b) compounds display single-molecule magnet behavior modulated by their spin ground state.

  12. Modification of an Iranian clinoptilolite nano-particles by hexadecyltrimethyl ammonium cationic surfactant and dithizone for removal of Pb(II) from aqueous solution.

    PubMed

    Anari-Anaraki, Mostafa; Nezamzadeh-Ejhieh, Alireza

    2015-02-15

    Natural clinoptilolite tuff was mechanically converted to micro (MCP) and nano (NCP) particles. The MCP and NCP powders were respectively modified with hexadecyltrimethyl ammonium bromide (HDTMA) and dithizone (DTZ). The raw and modified samples were characterized by X-ray diffraction (XRD), Fourier transformation infra red (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) and thermogravimetry (TG) and used for the removal of Pb(II) from aqueous solution. The results confirm that both ion exchange and complexation processes are responsible for removal of Pb(II) cations in the modified samples, while Pb(II) cations were only removed via an ion exchange process by the raw clinoptilolite. In this sorbent, the anionic removal property of surfactant modified zeolites (SMZs) changed to cationic removal property by an additional modification step. The best removal efficiency was observed by NCP-HDTMA-DTZ at the following experimental conditions: C(Pb(II)): 800 mg L(-1), HDTMA dosage: 0.2 mol L(-1), DTZ dosage: 5 mmol L(-1), contact time of DTZ with NCP-HDTMA: 1800 min and contact time of the sorbent with Pb(II): 360 min. The NCP-HDTMA-DTZ sorbent showed good efficiency for the removal of lead in the presence of different multivalent cations. Adsorption isotherms of Pb(II) ions obey the Langmuir equation that indicate the monolayer sorption of Pb(II). The adsorption kinetics based on the pseudo-second-order rate equation indicates that the rate limiting step involving a chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneous process.

  13. Density functional theory of the CuA -like Cu2 S2 diamond core in Cu 2II(NGuaS)2 Cl2.

    PubMed

    Witte, M; Gerstmann, U; Neuba, A; Henkel, G; Schmidt, W G

    2016-04-30

    Density functional theory (DFT) calculations with localized as well as plane-wave basis functions are performed for the recently reported dicopper thiolate species Cu2 (NGuaS)2 Cl2 [NGuaS = 2-(1,1,3,3-tetramethylguanidino) benzenethiolate, C11 H16 N3 S] and its bromo derivative [Neuba et al., Angew. Chem. Int. Ed. 2012, 51, 1714.]. For both hybrid and semilocal functionals, the neutral complexes are found to have broken symmetry (BS) character, with electron paramagnetic resonance silent, antiferromagnetically coupled [Cu(2+) …Cu(2+) ] site in which the coupling is driven by super exchange interaction within the Cu2 S2 diamond core. The accurate theoretical description of the geometric structure, however, provides a major challenge for DFT: (i) the multideterminant character of the ground state wave function has to be covered by the BS approach. It requires (ii) metageneralized gradient approximations, that is hybrid functionals with an explicit dependence on the kinetic energy of the individual orbitals: In combination with a dispersion correction, the metafunctional TPSSh results in a CuCu distance close to the experimentally observed value of 2.7 Å. For the negative charge state of the complex, a mixed-valent [Cu(1.5+) …Cu(1.5+) ] electronic structure with a smaller CuCu distance of 2.6 Å is predicted, similar to the value of the CuA site of cytochrome c oxidase.

  14. Stronger enhancer II/core promoter activities of hepatitis B virus isolates of B2 subgenotype than those of C2 subgenotype

    PubMed Central

    Qin, Yanli; Zhou, Xueshi; Jia, Haodi; Chen, Chaoyang; Zhao, Weifeng; Zhang, Jiming; Tong, Shuping

    2016-01-01

    Hepatitis B virus (HBV) genotype C causes prolonged chronic infection and increased risk for liver cancer than genotype B. Our previous work revealed lower replication capacity of wild-type genotype C2 than B2 isolates. HBV DNA replication is driven by pregenomic RNA, which is controlled by core promoter (CP) and further augmented by enhancer I (ENI) and enhancer II (ENII). DNA fragments covering these regulatory elements were amplified from B2 and C2 isolates to generate luciferase reporter constructs. As ENII is fully embedded in CP, we inserted HBV DNA fragments in the sense orientation to determine their combined activities, and in the antisense orientation to measure enhancer activities alone. Genotype B2 isolates displayed higher ENI+ENII+CP, ENII+CP, and ENII activities, but not ENI or ENI+ENII activity, than C2 isolates. The higher ENII+CP activity was partly attributable to 4 positions displaying genotype-specific variability. Exchanging CP region was sufficient to revert the replication phenotypes of several B2 and C2 clones tested. These results suggest that a weaker ENII and/or CP at least partly accounts for the lower replication capacities of wild-type C2 isolates, which could drive the subsequent acquisition of CP mutations. Such mutations increase genome replication and are implicated in liver cancer development. PMID:27461034

  15. Stronger enhancer II/core promoter activities of hepatitis B virus isolates of B2 subgenotype than those of C2 subgenotype.

    PubMed

    Qin, Yanli; Zhou, Xueshi; Jia, Haodi; Chen, Chaoyang; Zhao, Weifeng; Zhang, Jiming; Tong, Shuping

    2016-07-27

    Hepatitis B virus (HBV) genotype C causes prolonged chronic infection and increased risk for liver cancer than genotype B. Our previous work revealed lower replication capacity of wild-type genotype C2 than B2 isolates. HBV DNA replication is driven by pregenomic RNA, which is controlled by core promoter (CP) and further augmented by enhancer I (ENI) and enhancer II (ENII). DNA fragments covering these regulatory elements were amplified from B2 and C2 isolates to generate luciferase reporter constructs. As ENII is fully embedded in CP, we inserted HBV DNA fragments in the sense orientation to determine their combined activities, and in the antisense orientation to measure enhancer activities alone. Genotype B2 isolates displayed higher ENI+ENII+CP, ENII+CP, and ENII activities, but not ENI or ENI+ENII activity, than C2 isolates. The higher ENII+CP activity was partly attributable to 4 positions displaying genotype-specific variability. Exchanging CP region was sufficient to revert the replication phenotypes of several B2 and C2 clones tested. These results suggest that a weaker ENII and/or CP at least partly accounts for the lower replication capacities of wild-type C2 isolates, which could drive the subsequent acquisition of CP mutations. Such mutations increase genome replication and are implicated in liver cancer development.

  16. Direct micromechanics derivation and DEM confirmation of the elastic moduli of isotropic particulate materials:. Part II Particle rotation

    NASA Astrophysics Data System (ADS)

    Fleischmann, J. A.; Drugan, W. J.; Plesha, M. E.

    2013-07-01

    In Part I, Fleischmann et al. (2013), we performed theoretical analyses of three cubic packings of uniform spheres (simple, body-centered, and face-centered) assuming no particle rotation, employed these results to derive the effective elastic moduli for a statistically isotropic particulate material, and assessed these results by performing numerical discrete element method (DEM) simulations with particle rotations prohibited. In this second part, we explore the effect that particle rotation has on the overall elastic moduli of a statistically isotropic particulate material. We do this both theoretically, by re-analyzing the elementary cells of the three cubic packings with particle rotation allowed, which leads to the introduction of an internal parameter to measure zero-energy rotations at the local level, and numerically via DEM simulations in which particle rotation is unrestrained. We find that the effects of particle rotation cannot be neglected. For unrestrained particle rotation, we find that the self-consistent homogenization assumption applied to the locally body-centered cubic packing incorporating particle rotation effects most accurately predicts the measured values of the overall elastic moduli obtained from the DEM simulations, in particular Poisson's ratio. Our new self-consistent results and theoretical modeling of particle rotation effects together lead to significantly better theoretical predictions of Poisson's ratio than all prior published results. Moreover, our results are based on a direct micromechanics analysis of specific geometrical packings of uniform spheres, in contrast to prior theoretical analyses based on hypotheses involving overall inter-particle contact distributions. Thus, our results permit a direct assessment of the reasons for the theory-experiment discrepancies noted in the literature with regard to previous theoretical derivations of the macroscopic elastic moduli for particulate materials, and our new theoretical results

  17. 1.1 μm superficially porous particles for liquid chromatography: part II: column packing and chromatographic performance.

    PubMed

    Blue, Laura E; Jorgenson, James W

    2015-02-06

    The predicted advantages of superficially porous particles over totally porous particles are decreased eddy dispersion, longitudinal diffusion, and resistance to mass transfer contributions to the theoretical plate height. While sub-2 micron superficially porous particles are commercially available, further improvements in performance are predicted by decreasing the particle diameter and decreasing the porous layer thickness. 1.1 μm superficially porous particles with 187Å pores have been synthesized using a layer-by-layer method tuned for production of smaller diameter particles. Following synthesis, these particles were packed into 30 μm i.d. capillary columns and their chromatographic performance evaluated using electrochemical detection. Based on the initial studies, the column efficiency did not meet theory, but was similar to the commercially available products tested. It is believed that the column packing process plays a critical role in the sub-par column performance. To determine if column efficiency could be predicted by solvent-particle interactions, in-solution optical microscopy and sedimentation velocity of particles in various slurry solvents were investigated and compared to column performance. Aggregating slurry solvents, such as methanol were found to produce columns with increased efficiency. The hmin for a column packed with an acetone slurry and a methanol slurry at 3mg/mL were found to be 6.3 and 3.5, respectively. Increasing the slurry concentration to 25mg/mL further improved the efficiency, producing a column with an hmin of 2.6. These efficiency results were accurately predicted by in-solution optical microscopy.

  18. Development of a candidate influenza vaccine based on virus-like particles displaying influenza M2e peptide into the immunodominant region of hepatitis B core antigen: Broad protective efficacy of particles carrying four copies of M2e.

    PubMed

    Tsybalova, Liudmila M; Stepanova, Liudmila A; Kuprianov, Victor V; Blokhina, Elena A; Potapchuk, Marina V; Korotkov, Alexander V; Gorshkov, Andrey N; Kasyanenko, Marina A; Ravin, Nikolai V; Kiselev, Oleg I

    2015-06-26

    A long-term objective when designing influenza vaccines is to create one with broad cross-reactivity that will provide effective control over influenza, no matter which strain has caused the disease. Here we summarize the results from an investigation into the immunogenic and protective capacities inherent in variations of a recombinant protein, HBc/4M2e. This protein contains four copies of the ectodomain from the influenza virus protein M2 (M2e) fused within the immunodominant loop of the hepatitis B virus core antigen (HBc). Variations of this basic design include preparations containing M2e from the consensus human influenza virus; the M2e from the highly pathogenic avian A/H5N1 virus and a combination of two copies from human and two copies from avian influenza viruses. Intramuscular delivery in mice with preparations containing four identical copies of M2e induced high IgG titers in blood sera and bronchoalveolar lavages. It also provoked the formation of memory T-cells and antibodies were retained in the blood sera for a significant period of time post immunization. Furthermore, these preparations prevented the death of 75-100% of animals, which were challenged with lethal doses of virus. This resulted in a 1.2-3.5 log10 decrease in viral replication within the lungs. Moreover, HBc particles carrying only "human" or "avian" M2e displayed cross-reactivity in relation to human (A/H1N1, A/H2N2 and A/H3N2) or A/H5N1 and A(H1N1)pdm09 viruses, respectively; however, with the particles carrying both "human" and "avian" M2e this effect was much weaker, especially in relation to influenza virus A/H5N1. It is apparent from this work that to quickly produce vaccine for a pandemic it would be necessary to have several variations of a recombinant protein, containing four copies of M2e (each one against a group of likely influenza virus strains) with these relevant constructs housed within a comprehensive collection Escherichia coli-producers and maintained ready for use.

  19. General coalescence conditions for the exact wave functions. II. Higher-order relations for many-particle systems.

    PubMed

    Kurokawa, Yusaku I; Nakashima, Hiroyuki; Nakatsuji, Hiroshi

    2014-06-07

    We derived the necessary conditions that must be satisfied by the non-relativistic time-independent exact wave functions for many-particle systems at a two-particle coalescence (or cusp) point. Some simple conditions are known to be Kato's cusp condition (CC) and Rassolov and Chipman's CC. In a previous study, we derived an infinite number of necessary conditions that two-particle wave functions must satisfy at a coalescence point. In the present study, we extend these conditions to many-particle systems. They are called general coalescence conditions (GCCs), and Kato's CC and Rassolov and Chipman's CC are included as special conditions. GCCs can be applied not only to Coulombic systems but also to any system in which the interaction between two particles is represented in a power series of inter-particle distances. We confirmed the correctness of our derivation of the GCCs by applying the exact wave function of a harmonium in electron-electron and electron-nucleus coalescence situations. In addition, we applied the free complement (FC) wave functions of a helium atom to the GCCs to examine the accuracy of the FC wave function in the context of a coalescence situation.

  20. Facile synthesis of copper(II)-decorated magnetic particles for selective removal of hemoglobin from blood samples.

    PubMed

    Ding, Chun; Ma, Xiangdong; Yao, Xin; Jia, Li

    2015-12-11

    In this report, the Cu(2+)-immobilized magnetic particles were prepared by a facile route and they were used as adsorbents for removal of high abundance of hemoglobin in blood based on immobilized metal affinity chromatography. Ethylenediaminetetraacetic acid modified magnetic particles (EDTA-Fe3O4) were first synthesized through a one-pot solvothermal method and then charged with copper ions. The as-prepared Cu(2+)-EDTA-Fe3O4 particles were characterized by Fourier transform infrared spectrometry, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, vibrating sample magnetometry and zeta potential. Factors affecting the adsorption of bovine hemoglobin on Cu(2+)-EDTA-Fe3O4 particles (including contact time, solution pH, ionic strength and initial concentration of protein) were investigated. The adsorption process followed a pseudo-second-order kinetic model and the adsorption equilibrium could be achieved in 60min. The adsorption isotherm data could be well described by a Langmuir model and the maximum adsorption capacity was 1250mgg(-1). The as-prepared particles showed high efficiency and excellent selectivity for removal of hemoglobin from bovine and human blood. The removal process integrated the selectivity of immobilized metal affinity chromatography and the convenience of magnetic separation. The results demonstrated that Cu(2+)-EDTA-Fe3O4 particles had potential application in removal of abundant histidine-rich proteins in biomedical diagnosis analysis.

  1. Specific mutations in the enhancer II/core promoter/precore regions of hepatitis B virus subgenotype C2 in Korean patients with hepatocellular carcinoma.

    PubMed

    Kim, Ja Kyung; Chang, Hye Young; Lee, Jung Min; Baatarkhuu, Oidov; Yoon, Young Joon; Park, Jun Yong; Kim, Do Young; Han, Kwang-Hyub; Chon, Chae Yoon; Ahn, Sang Hoon

    2009-06-01

    Recently, hepatitis B virus (HBV) genotypes and mutations have been reported to be related to hepatocellular carcinoma (HCC). This cross-sectional case-control study examined the relationship between HCC and mutations in the enhancer II/core promoter and precore regions of HBV by comparing 135 Korean HCC patients infected with HBV genotype C2 (HBV/C2; HCC group) with 135 age-, sex-, and hepatitis B e antigen (HBeAg) status-matched patients without HCC (non- HCC group). Age and sex were also matched between HBeAg-positive and -negative patients. The prevalence of T1653, A1689, V1753, T1762/A1764, T1846, A1850, C1858, and A1896 mutations was evaluated in this population. The prevalence of the T1653 mutation in the box alpha region, the T1689 [corrected] mutation in between the box alpha and beta regions, and the T1762/A1764 mutations in the basal core promoter region was significantly higher in the HCC group compared to the non-HCC group (8.9% vs. 2.2%, P = 0.017; 19.3% vs. 4.4%, P < 0.001; and 60.7% vs. 22.2%; P < 0.001). Among HBeAg-negative patients, the frequency of the T1653 mutation was higher in the HCC group. Regardless of HBeAg status, the prevalence of the T1689, [corrected] and T1762/A1764 mutations was higher in the HCC group than in the non-HCC group. However, no association was observed between mutations in the precore region and HCC. Upon multivariate analysis, the presence of the T1653, T1689, [corrected] and T1762/A1764 mutations was an independent predictive factor for HCC. The addition of the T1653 or T1689 [corrected] mutation to T1762/A1764 increased the risk of HCC. In conclusion, the T1653, T1689, [corrected] and/or T1762/A1764 mutations were associated with the development of HCC in Korean patients infected with HBV/C2.

  2. A biomathematical model of particle clearance and retention in the lungs of coal miners. II. Evaluation of variability and uncertainty.

    PubMed

    Kuempel, E D; Tran, C L; Smith, R J; Bailer, A J

    2001-08-01

    The objective of this study is to investigate the sources of variability and uncertainty in a previously developed human lung dosimetry model. That three-compartment model describes the retention and clearance kinetics of respirable particles in the gas-exchange region of the lungs. It was calibrated using exposure histories and lung dust burden data in U.S. coal miners. A multivariate parameter estimation and optimization method was developed for fitting the dosimetry model to these human data. Models with various ass