WorldWideScience

Sample records for unique dispersion properties

  1. Unique morphology of dispersed clay particles in a polymer nanocomposite

    CSIR Research Space (South Africa)

    Malwela, T

    2011-02-01

    Full Text Available This communication reports a unique morphology of dispersed clay particles in a polymer nanocomposite. A nanocomposite of poly[butylene succinate)-co-adipate] (PBSA) with 3 wt% of organically modified montmorillonite was prepared by melt...

  2. Dispersion properties of photonic crystal fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Dridi, Kim

    1998-01-01

    Approximate dispersion and bending properties of all-silica two-dimensional photonic crystal fibres are characterised by the combination of an effective-index model and classical analysis tools for optical fibres. We believe for the first time to have predicted the dispersion properties of photonic...... crystal fibres. The results strongly indicate that these fibres have potential applications as dispersion managing components...

  3. Unique properties of Drosophila spermatocyte primary cilia

    Directory of Open Access Journals (Sweden)

    Maria Giovanna Riparbelli

    2013-09-01

    The primary cilium is an essential organelle required for animal development and adult homeostasis that is found on most animal cells. The primary cilium contains a microtubule-based axoneme cytoskeleton that typically grows from the mother centriole in G0/G1 phase of the cell cycle as a membrane-bound compartment that protrudes from the cell surface. A unique system of bidirectional transport, intraflagellar transport (IFT, maintains the structure and function of cilia. While the axoneme is dynamic, growing and shrinking at its tip, at the same time it is very stable to the effects of microtubule-targeting drugs. The primary cilia found on Drosophila spermatocytes diverge from the general rules of primary cilium biology in several respects. Among these unique attributes, spermatocyte cilia assemble from all four centrioles in an IFT-independent manner in G2 phase, and persist continuously through two cell divisions. Here, we show that Drosophila spermatocyte primary cilia are extremely sensitive to microtubule-targeting drugs, unlike their mammalian counterparts. Spermatocyte cilia and their axonemes fail to assemble or be maintained upon nocodazole treatment, while centriole replication appears unperturbed. On the other hand, paclitaxel (Taxol, a microtubule-stabilizing drug, disrupted transition zone assembly and anchoring to the plasma membrane while causing spermatocyte primary cilia to grow extensively long during the assembly/elongation phase, but did not overtly affect the centrioles. However, once assembled to their mature length, spermatocyte cilia appeared unaffected by Taxol. The effects of these drugs on axoneme dynamics further demonstrate that spermatocyte primary cilia are endowed with unique assembly properties.

  4. Robust diamond meshes with unique wettability properties.

    Science.gov (United States)

    Yang, Yizhou; Li, Hongdong; Cheng, Shaoheng; Zou, Guangtian; Wang, Chuanxi; Lin, Quan

    2014-03-18

    Robust diamond meshes with excellent superhydrophobic and superoleophilic properties have been fabricated. Superhydrophobicity is observed for water with varying pH from 1 to 14 with good recyclability. Reversible superhydrophobicity and hydrophilicity can be easily controlled. The diamond meshes show highly efficient water-oil separation and water pH droplet transference.

  5. Existence and uniqueness of positive solutions for a nonlocal dispersal population model

    Directory of Open Access Journals (Sweden)

    Jian-Wen Sun

    2014-06-01

    Full Text Available In this article, we study the solutions of a nonlocal dispersal equation with a spatial weight representing competitions and aggregation. To overcome the limitations of comparison principles, we introduce new definitions of upper-lower solutions. The proof of existence and uniqueness of positive solutions is based on the method of monotone iteration sequences.

  6. Unique coexistence of dispersion stability and nanoparticle chemisorption in alkylamine/alkylacid encapsulated silver nanocolloids.

    Science.gov (United States)

    Aoshima, Keisuke; Hirakawa, Yuya; Togashi, Takanari; Kurihara, Masato; Arai, Shunto; Hasegawa, Tatsuo

    2018-04-17

    Surface encapsulation of metal nanoparticles (NPs) is fundamental to achieve sufficient dispersion stability of metal nanocolloids, or metal nanoink. However, the feature is incompatible with surface reactive nature of the metal NPs, although these features are both essential to realizing the functional applications into printed electronics technologies. Here we show that two different kinds of encapsulation for silver NPs (AgNPs) by alkylamine and alkylacid together are the key to achieve unique compatibility between the high dispersion stability as dense nanoclolloids and the AgNP chemisorption printing on activated patterned polymer surfaces. Advanced confocal dynamic light scattering study reveals that an additive trace amount of oleic acid is the critical parameter for controlling the dispersion and coagulative (or surface-reactive) characteristics of the silver nanocolloids. The composition of the disperse media is also important for obtaining highly concentrated but low-viscosity silver nanocolloids that show very stable dispersion. The results demonstrate that the high-resolution AgNP chemisorption printing is possible only by using unique silver nanocolloids composed of an exceptional balance of ligand formulation and dispersant composition.

  7. Analytic properties of the whistler dispersion function

    International Nuclear Information System (INIS)

    Daniell, G.J.

    1986-01-01

    The analytic properties of the dispersion function of a whistler are investigated in the complex frequency plane. It possesses a pole and a branch point at a frequency equal to the minimum value of the electron gyrofrequency along the path of propagation. An integral equation relates the dispersion function to the distribution of magnetospheric electrons along the path and the solution of this equation is obtained. It is found that the electron density in the equatorial plane is very simply related to the dispersion function. A discussion of approximate formulae to represent the dispersion shows how particular terms can be related to attributes of the electron density distribution, and a new approximate formula is proposed. (author)

  8. Tailoring Dispersion properties of photonic crystal waveguides by topology optimization

    DEFF Research Database (Denmark)

    Stainko, Roman; Sigmund, Ole

    2007-01-01

    based design updates. The goal of the optimization process is to come up with slow light, zero group velocity dispersion photonic waveguides or photonic waveguides with tailored dispersion properties for dispersion compensation purposes. Two examples concerning reproduction of a specific dispersion...

  9. The Mysteries of Diamonds: Bizarre History, Amazing Properties, Unique Applications

    International Nuclear Information System (INIS)

    Kagan, Harris

    2008-01-01

    Diamonds have been a prized material throughout history. They are scarce and beautiful, wars have been fought over them, and they remain today a symbol of wealth and power. Diamonds also have exceptional physical properties which can lead to unique applications in science. There are now techniques to artificially synthesize diamonds of extraordinarily high quality. In this talk, Professor Kagan will discuss the history of diamonds, their bizarre properties, and their manufacture and use for 21st century science.

  10. The Mysteries of Diamonds: Bizarre History, Amazing Properties, Unique Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kagan, Harris (Ohio State University)

    2008-06-24

    Diamonds have been a prized material throughout history. They are scarce and beautiful, wars have been fought over them, and they remain today a symbol of wealth and power. Diamonds also have exceptional physical properties which can lead to unique applications in science. There are now techniques to artificially synthesize diamonds of extraordinarily high quality. In this talk, Professor Kagan will discuss the history of diamonds, their bizarre properties, and their manufacture and use for 21st century science.

  11. Unique microstructure and excellent mechanical properties of ADI

    Directory of Open Access Journals (Sweden)

    Jincheng Liu

    2006-11-01

    Full Text Available Amongst the cast iron family, ADI has a unique microstructure and an excellent, optimised combination of mechanical properties. The main microstructure of ADI is ausferrite, which is a mixture ofextremely fine acicular ferrite and stable, high carbon austenite. There are two types of austenite in ADI:(1 the coarser and more equiaxed blocks of austenite between non-parallel acicular structures, which exist mainly in the last solidified area, and (2 the thin films of ustenite between the individual ferriteplatelets in the acicular structure. It is this unique microstructure, which gives ADI its excellent static and dynamic properties, and good low temperature impact toughness. The effect of microstructure on the mechanical properties is explained in more detail by examining the microstructure at the atomic scale. Considering the nanometer grain sizes, the unique microstructure, the excellent mechanical properties,good castability, (which enables near net shape components to be produced economically and in large volumes, and the fact that it can be 100% recycled, it is not overemphasized to call ADI a high-tech,nanometer and “green” material. ADI still has the potential to be further improved and its production and the number of applications for ADI will continue to grow, driven by the resultant cost savings over alternative materials.

  12. Unique molecular properties of superoxide dismutase from teleost fish skin.

    Science.gov (United States)

    Nakano, T; Sato, M; Takeuchi, M

    1995-02-27

    A unique Cu,Zn-SOD was found and isolated from plaice Paralichthys olivaceus skin. Surprisingly, the properties of purified fish skin SOD were very different from those of SOD from other sources reported so far. The purified SOD was composed of four same subunits of 16 kDa and the molecular weight of the native SOD was found to be around 65 kDa. The dominant amino acids of the SOD were Ser, Thr, Pro and Glu. Above 70 degrees C, thermostability of the SOD was much lower than that of bovine erythrocyte Cu,Zn-SOD.

  13. Effects of chemical dispersants on oil physical properties and dispersion. Volume 1

    International Nuclear Information System (INIS)

    Khelifa, A.; Fingas, M.; Hollebone, B.P.; Brown, C.E.; Pjontek, D.

    2007-01-01

    Laboratory and field testing have shown that the dispersion of oil spilled in water is influenced by chemical dispersants via the modification of the interfacial properties of the oil, such as oil-brine interfacial tension (IFT). This study focused on new laboratory experiments that measured the effects on the physical properties and dispersion of oil, with particular reference to the effects of chemical dispersants on IFT and oil viscosity and the subsequent effects on oil droplet formation. Experiments were conducted at 15 degrees C using Arabian Medium, Alaska North Slope and South Louisiana crude and Corexit 9500 and Corexit 9527 chemical dispersants. The dispersants were denser than the 3 oils. The effect of IFT reduction on oil dispersion was measured and showed substantial reduction in the size and enhancement of the concentration of oil droplets in the water column. It was shown that the brine-oil IFT associated with the 3 crudes reduced to less than 3.6 mN/m with the application of the chemical dispersants, even at a low dispersant-to-oil ratio (DOR) value of 1:200. The use of chemical dispersants increased the viscosity of the dispersant-oil mixture up to 40 per cent over the neat crude oil. It was shown that for each mixing condition, an optimum value of DOR exists that provides for maximal dispersant effectiveness. The IFT reaches maximum reduction at optimum DOR. It was suggested that oil spill modelling can be improved with further study of IFT reduction with DOR and variations of critical micelle concentration with the type and solubility of chemical dispersant, oil type and oil to water ratio. 13 refs., 3 tabs., 7 figs

  14. Review on properties, dispersion and toxicology of carbon nanotubes

    International Nuclear Information System (INIS)

    Saeed, K.

    2010-01-01

    Carbon nanotubes (CNTs) have the most intensely studied nano structures because of their unique properties. There are two types of carbon nanotubes CNTs, single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), prepared by chemical-vapour deposition (CVD), plasma enhanced chemical-vapour deposition, thermal chemical vapour deposition, Vapour phase growth, Arc discharge and Lasser ablation. Both single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) possess high mechanical and electrical conductivity, ultra-light weight, high aspect ratio and have excellent chemical and thermal stabilities. They also possess semi- and metallic-conductive properties depending upon their chirality. This review focuses on progress toward functionalization (not only dispersed nano tube but also dramatically improve their solubility), preparation and purification, composites and the toxicity of the carbon nanotubes (CNTs). The functional groups attached to carbon nanotubes (CNTs) should react with polymers and improve the mechanical properties of the nano composites. Carbon nanotubes (CNTs) has significant application in pharmaceutical field such as drug delivery and nano medicine, but the available literature also suggests that carbon nanotubes (CNTs) may have unusual toxicity and have more adverse effects than the same mass of nano size carbon and quartz. (author)

  15. A review on thermophysical properties of nanoparticle dispersed phase change materials

    International Nuclear Information System (INIS)

    Kibria, M.A.; Anisur, M.R.; Mahfuz, M.H.; Saidur, R.; Metselaar, I.H.S.C.

    2015-01-01

    Highlights: • Thermo physical properties of PCM could be enhanced by dispersing nanoparticles. • Surface/physical properties of nanoparticle could affect the thermal properties of PCM. • CNT and CNF showed better performance to enhance the thermal properties of PCM. • Some predictions in NePCM literature needs further investigations. - Abstract: A review of current experimental studies on variations in thermophysical properties of phase change material (PCM) due to dispersion of nanoparticles is presented in this article. Dispersed carbon nanotubes/fiber and different metal/metal oxide nano particles in paraffin and fatty acids might be a solution to improve latent heat thermal storage performance. Thermophysical properties such as thermal conductivity, latent heat, viscosity and super cooling of phase change materials (PCM) could be changed for different physical properties of dispersed nanoparticle such as size, shape, concentration and surface properties. Among the nano particles, comparatively carbon nanotubes and carbon nano fiber have shown better performance in enhancing the thermal properties of PCM for their unique properties. The present review will focus on the studies that describe how the surface, chemical and physical properties of nanoparticle could affect the thermal properties of PCM with the help of available explanations in the literature

  16. Thermophysical properties of dispersed metal materials

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Hyun; Kim, Jong Chul [KRISS, Taejeon (Korea)

    2002-04-01

    Thermal conductivities of the preliminarily fabricated U-Mo dispersion fuel meats have been measured to estimate the center temperature of the irradiation fuels. Thermal conductivities at temperatures ranging from room temperature to 500 .deg. C were calculated by measuring diffusivities, specific heat capacities and densities of dispersion fuel meats. The molybdenum content of fuel meats was varied to be 6wt%, 8wt%, and 10wt% and the volume fraction of U-Mo fuel powders were changed to be 10 vol%, 30vol%, 40 vol%, and 50 vol%. 13 refs., 39 figs., 13 tabs. (Author)

  17. Anaerobic Ammonium-Oxidizing Bacteria: Unique Microorganisms with Exceptional Properties

    Science.gov (United States)

    Jetten, Mike S. M.

    2012-01-01

    Summary: Anaerobic ammonium-oxidizing (anammox) bacteria defy many microbiological concepts and share numerous properties with both eukaryotes and archaea. Among their most intriguing characteristics are their compartmentalized cell plan and archaeon-like cell wall. Here we review our current knowledge about anammox cell biology. The anammox cell is divided into three separate compartments by bilayer membranes. The anammox cell consists of (from outside to inside) the cell wall, paryphoplasm, riboplasm, and anammoxosome. Not much is known about the composition or function of both the anammox cell wall and the paryphoplasm compartment. The cell wall is proposed to be proteinaceous and to lack both peptidoglycan and an outer membrane typical of Gram-negative bacteria. The function of the paryphoplasm is unknown, but it contains the cell division ring. The riboplasm resembles the standard cytoplasmic compartment of other bacteria; it contains ribosomes and the nucleoid. The anammoxosome occupies most of the cell volume and is a so-called “prokaryotic organelle” analogous to the eukaryotic mitochondrion. This is the site where the anammox reaction takes place, coupled over the curved anammoxosome membrane, possibly giving rise to a proton motive force and subsequent ATP synthesis. With these unique properties, anammox bacteria are food for thought concerning the early evolution of the domains Bacteria, Archaea, and Eukarya. PMID:22933561

  18. Soil properties from seismic intrinsic dispersion

    NARCIS (Netherlands)

    Zhubayev, A.S.

    2014-01-01

    Theoretical and experimental studies in the past have shown the sensitivity of seismic waves to soil/rock properties, such as composition, porosity, pore fluid, and permeability. However, quantitative characterization of these properties has remained challenging. In case of unconsolidated soils, the

  19. Physico-chemical and microstructural properties of food dispersions

    OpenAIRE

    Glicerina, Virginia Teresa

    2014-01-01

    The macroscopic properties of oily food dispersions, such as rheology, mechanical strength, sensory attributes (e.g. mouth feel, texture and even flavour release) and as well as engineering properties are strongly determined by their microstructure, that is considered a key parameter in the understanding of the foods behaviour . In particular the rheological properties of these matrices are largely influenced by their processing techniques, particle size distribution and composition of ingred...

  20. Advanced statistical properties of dispersing billiards

    CERN Document Server

    Chernov, N

    2005-01-01

    A new approach to statistical properties of hyperbolic dynamical systems emerged recently; it was introduced by L.-S.~Young and modified by D.~Dolgopyat. It is based on coupling method borrowed from probability theory. We apply it here to one of the most physically interesting models -- Sinai billiards. It allows us to derive a series of new results, as well as make significant improvements in the existing results. First we establish sharp bounds on correlations (including multiple correlations). Then we use our correlation bounds to obtain the central limit theorem (CLT), the almost sure invariance principle (ASIP), the law of iterated logarithms, and integral tests.

  1. Dispersive elastic properties of Dzyaloshinskii domain walls

    Science.gov (United States)

    Pellegren, James; Lau, Derek; Sokalski, Vincent

    Recent studies on the asymmetric field-driven growth of magnetic bubble domains in perpendicular thin films exhibiting an interfacial Dzyaloshinskii-Moriya interaction (DMI) have provided a wealth of experimental evidence to validate models of creep phenomena, as key properties of the domain wall (DW) can be altered with the application of an external in-plane magnetic field. While asymmetric growth behavior has been attributed to the highly anisotropic DW energy, σ (θ) , which results from the combination of DMI and the in-plane field, many experimental results remain anomalous. In this work, we demonstrate that the anisotropy of DW energy alters the elastic response of the DW as characterized by the surface stiffness, σ (θ) = σ (θ) + σ (θ) , and evaluate the impact of this stiffness on the creep law. We find that at in-plane fields larger than and antiparallel to the effective field due to DMI, the DW stiffness decreases rapidly, suggesting that higher energy walls can actually become more mobile than their low energy counterparts. This result is consistent with experiments on CoNi multilayer films where velocity curves for domain walls with DMI fields parallel and antiparallel to the applied field cross over at high in-plane fields.

  2. Synthesis and properties of amphiphilic hyperbranched polyethers as pigment dispersant

    Science.gov (United States)

    Xu, Q.; Zhou, Y. J.; Long, S. J.; Liu, Y. G.; Li, J. H.

    2018-01-01

    Hyperbranched polymers possess prominent properties such as low viscosity, good solubility, high rheological property, environmental non-toxic, and so on, which have potential applications in coatings. In this study, the amphiphilic hyperbranched polyethers (AHPs) consisting of hydrophobic hyperbranched polyethers core and hydrophilic poly (ethylene glycol) arms with different degree of branching (DB) under various reaction temperatures was prepared by the cation ring-opening polymerization. Their structures were characterized by IR, 13CNMR and GPC. Their dispersion properties for pigment particles were investigated. The AHP47 with 0.47 DB was found to have good dispersion properties for Yellow HGR. This work would provide experimental data and theoretical foundation for the application of hyperbranched polyethers in environmental protection coating.

  3. Viscoelasticity and diffusional properties of colloidal model dispersions

    CERN Document Server

    Naegele, G

    2003-01-01

    We examine linear viscoelastic, and translational and rotational diffusion properties of colloidal model dispersions. Theoretical results are discussed, in comparison with experiments, for monodisperse suspensions of charged and neutral colloidal spheres, and for binary dispersions of differently sized tracer and host particles. The theoretical methods employed comprise a mode-coupling scheme for Brownian particles, and a rooted cluster expansion scheme of tracer diffusion with two- and three-body hydrodynamic interactions included. We analyse in particular the validity of various empirical generalized Stokes-Einstein-Debye (SED) relations between the (dynamic) shear viscosity and translational/rotational diffusion coefficients. Some of these generalized SED relations are basic to microrheological measurements aimed at characterizing the viscoelasticity of complex fluids on the basis of the diffusional properties of immersed tracer particles.

  4. Viscoelasticity and diffusional properties of colloidal model dispersions

    International Nuclear Information System (INIS)

    Naegele, Gerhard

    2003-01-01

    We examine linear viscoelastic, and translational and rotational diffusion properties of colloidal model dispersions. Theoretical results are discussed, in comparison with experiments, for monodisperse suspensions of charged and neutral colloidal spheres, and for binary dispersions of differently sized tracer and host particles. The theoretical methods employed comprise a mode-coupling scheme for Brownian particles, and a rooted cluster expansion scheme of tracer diffusion with two- and three-body hydrodynamic interactions included. We analyse in particular the validity of various empirical generalized Stokes-Einstein-Debye (SED) relations between the (dynamic) shear viscosity and translational/rotational diffusion coefficients. Some of these generalized SED relations are basic to microrheological measurements aimed at characterizing the viscoelasticity of complex fluids on the basis of the diffusional properties of immersed tracer particles

  5. Existence and Uniqueness of Positive Periodic Solutions for a Delayed Predator-Prey Model with Dispersion and Impulses

    Directory of Open Access Journals (Sweden)

    Zhenguo Luo

    2014-01-01

    Full Text Available An impulsive Lotka-Volterra type predator-prey model with prey dispersal in two-patch environments and time delays is investigated, where we assume the model of patches with a barrier only as far as the prey population is concerned, whereas the predator population has no barriers between patches. By applying the continuation theorem of coincidence degree theory and by means of a suitable Lyapunov functional, a set of easily verifiable sufficient conditions are obtained to guarantee the existence, uniqueness, and global stability of positive periodic solutions of the system. Some known results subject to the underlying systems without impulses are improved and generalized. As an application, we also give two examples to illustrate the feasibility of our main results.

  6. Unique properties associated with normal martensitic transition and strain glass transition – A simulation study

    International Nuclear Information System (INIS)

    Wang, Dong; Ni, Yan; Gao, Jinghui; Zhang, Zhen; Ren, Xiaobing; Wang, Yunzhi

    2013-01-01

    Highlights: ► We model the unique properties of strain glass which is different from that of normal martensite. ► We describe the importance of point defects in the formation of strain glass and related properties. ► The role of point defect can be attributed to global transition temperature effect (GTTE) and local field effect (LFE). -- Abstract: The transition behavior and unique properties associated with normal martensitic transition and strain glass transition are investigated by computer simulations using the phase field method. The simulations are based on a physical model that assumes that point defects alter the thermodynamic stability of martensite and create local lattice distortion. The simulation results show that strain glass transition exhibits different properties from those found in normal martensitic transformations. These unique properties include diffuse scattering pattern, “smear” elastic modulus peak, disappearance of heat flow peak and non-ergodicity. These simulation predictions agree well with the experimental observations

  7. Nanoclay Dispersion and its Effect on Properties of Waterborne Polyurethanes

    Directory of Open Access Journals (Sweden)

    H. Honarkar

    2014-01-01

    Full Text Available In recent years, waterborne polyurethanes as in coatings and adhesives formulations have attracted considerable attention because they are non-toxic, non-flammable and friendly to environment. Besides environmental management, the flexibility, low temperature property, high tensile strength, good adhesion and improved rheological property are specific properties of waterborne polyurethanes. Also low production cost of water borne polyurethanes over solvent-borne polyurethanes is also a reason for their applications. However, these materials have some defects such as weak water resistance and low adhesion in the moisture environment due to sensitivity of their hydrophilic ionic bonds, ether groups, urethane and ester groups to hydrolysis which need to be improved. Also, low heat resistance of these materials is due to a relatively low crystalline melting point or glass transition temperature of hard segments. One of the ways to solve this problem and improve its properties for different applications is the addition of inorganic fillers especially nano-sized layered silicates within polyurethane matrix. In this way water resistance, heat resistance, mechanical properties and modulus increase simultaneously. In this research, waterborne polyurethane nanocomposites with PTMG polyol, IPDI, DMPA (internal emulsifier, TEA (neutralizer and 1, 3 and 5weight % of Cloisite 30B as reinforcement were synthesized and characterized. Polarity of the samples was investigated by contact angle test and dispersion of nano particles in the samples was characterized by X-Ray and TEM, Thermal properties and dynamic mechanical properties were measured by TGA and DMTA, respectively. The results showed that incorporation of clay into polyurethanes did reduce water absorption and increased heat resistance, modulus, particle size and contact angle.In recent years, waterborne polyurethanes including coatings and adhesives have attracted considerable attention because they

  8. Dispersion properties of transverse waves in electrically polarized BECs

    International Nuclear Information System (INIS)

    Andreev, Pavel A; Kuz'menkov, L S

    2014-01-01

    Further development of the method of quantum hydrodynamics in applications for Bose–Einstein condensates (BECs) is presented. To consider the evolution of polarization direction along with particle movement, we have developed a corresponding set of quantum hydrodynamic equations. It includes equations of the polarization evolution and the polarization-current evolution along with the continuity equation and the Euler equation (the momentum-balance equation). Dispersion properties of the transverse waves, including the electromagnetic waves propagating through the BECs, are considered. To this end, we consider a full set of the Maxwell equations for the description of electromagnetic field dynamics. This approximation gives us the possibility of considering the electromagnetic waves along with the matter waves. We find a splitting of the electromagnetic-wave dispersion on two branches. As a result, we have four solutions, two for the electromagnetic waves and two for the matter waves; the last two are the concentration-polarization waves appearing as a generalization of the Bogoliubov mode. We also find that if the matter wave propagates perpendicular to the external electric field then the dipolar contribution does not disappear (as it follows from our generalization of the Bogoliubov spectrum). A small dipolar frequency shift exists in this case due to the transverse electric field of perturbation. (paper)

  9. Molecular and excited state properties of isomeric scarlet disperse dyes

    Science.gov (United States)

    Lim, Jihye; Szymczyk, Malgorzata; Mehraban, Nahid; Ding, Yi; Parrillo-Chapman, Lisa; El-Shafei, Ahmed; Freeman, Harold S.

    2018-06-01

    This work was part of an investigation aimed at characterizing the molecular and excited state properties of currently available disperse dyes developed to provide stability to extensive sunlight exposures when adsorbed on poly(ethylene terephthalate) (PET) fibers. Having completed the characterization of yellow, magenta, and cyan disperse dyes for PET-based fabrics used outdoors, our attention turned to the colors designed to enhance the color gamut of a standard 4-member (cyan/yellow/magenta/black) color set. The present study pertained specifically to the characterization of commercially available scarlet dyes. In this regard, HPLC analysis showed that a scarlet product used for PET coloration was mainly a 70/30 mixture of dyes, and the use of HRMS and single crystal X-ray diffraction analyses indicated that these two dyes were azo compounds derived from isomeric pyridine-based couplers which differed in the location of the primary amino (sbnd NH2) and anilino (sbnd NHPh) groups attached to the pyridine ring. One dye structure has the sbnd NHPh group para to the azo group (Sc2), while the other has that group in the ortho position (Sc3). The presence of either ortho substituent provides photostabilization through intramolecular H-bonding with the azo moiety. Further, results from molecular modeling studies showed that the lower excited state oxidation potential of Sc3 relative to that of Sc2 allows Sc3 to function as an energy quencher for the excited state of Sc2 - through thermodynamically favorable electron transfer.

  10. Simple display system of mechanical properties of cells and their dispersion.

    Directory of Open Access Journals (Sweden)

    Yuji Shimizu

    Full Text Available The mechanical properties of cells are unique indicators of their states and functions. Though, it is difficult to recognize the degrees of mechanical properties, due to small size of the cell and broad distribution of the mechanical properties. Here, we developed a simple virtual reality system for presenting the mechanical properties of cells and their dispersion using a haptic device and a PC. This system simulates atomic force microscopy (AFM nanoindentation experiments for floating cells in virtual environments. An operator can virtually position the AFM spherical probe over a round cell with the haptic handle on the PC monitor and feel the force interaction. The Young's modulus of mesenchymal stem cells and HEK293 cells in the floating state was measured by AFM. The distribution of the Young's modulus of these cells was broad, and the distribution complied with a log-normal pattern. To represent the mechanical properties together with the cell variance, we used log-normal distribution-dependent random number determined by the mode and variance values of the Young's modulus of these cells. The represented Young's modulus was determined for each touching event of the probe surface and the cell object, and the haptic device-generating force was calculated using a Hertz model corresponding to the indentation depth and the fixed Young's modulus value. Using this system, we can feel the mechanical properties and their dispersion in each cell type in real time. This system will help us not only recognize the degrees of mechanical properties of diverse cells but also share them with others.

  11. Effect of lime concentration on gelatinized maize starch dispersions properties.

    Science.gov (United States)

    Lobato-Calleros, C; Hernandez-Jaimes, C; Chavez-Esquivel, G; Meraz, M; Sosa, E; Lara, V H; Alvarez-Ramirez, J; Vernon-Carter, E J

    2015-04-01

    Maize starch was lime-cooked at 92 °C with 0.0-0.40% w/w Ca(OH)2. Optical micrographs showed that lime disrupted the integrity of insoluble remnants (ghosts) and increased the degree of syneresis of the gelatinized starch dispersions (GSD). The particle size distribution was monomodal, shifting to smaller sizes and narrower distributions with increasing lime concentration. X-ray patterns and FTIR spectra showed that crystallinity decreased to a minimum at lime concentration of 0.20% w/w. Lime-treated GSD exhibited thixotropic and viscoelastic behaviour. In the linear viscoelastic region the storage modulus was higher than the loss modulus, but a crossover between these moduli occurred in the non-linear viscoelastic region. The viscoelastic properties decreased with increased lime concentration. The electrochemical properties suggested that the amylopectin-rich remnants and the released amylose contained in the continuous matrix was firstly attacked by calcium ions at low lime levels (<0.20% w/w), disrupting the starch gel microstructure. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. A new look at C∗-simplicity and the unique trace property of a group

    DEFF Research Database (Denmark)

    Haagerup, U.

    2016-01-01

    We characterize when the reduced C∗-algebra of a non-trivial group has unique tracial state, respectively, is simple, in terms of Dixmier-type properties of the group C∗-algebra.We also give a simple proof of the recent result by Breuillard, Kalantar, Kennedy and Ozawa that the reduced C∗-algebra...

  13. Effects of uniquely processed cowpea and plantain flours on wheat bread properties

    Science.gov (United States)

    The effect of incorporating uniquely processed whole-seed cowpeas or plantain flours at 10 or 20 g/100 g in all-purpose flour on paste viscosity and bread-baking properties in model bread was determined. Flours from plantains processed as follows: unblanched plantains dried at 60 degrees C (PLC), so...

  14. Dispersion Corrected Structural Properties and Quasiparticle Band Gaps of Several Organic Energetic Solids.

    Science.gov (United States)

    Appalakondaiah, S; Vaitheeswaran, G; Lebègue, S

    2015-06-18

    We have performed ab initio calculations for a series of energetic solids to explore their structural and electronic properties. To evaluate the ground state volume of these molecular solids, different dispersion correction methods were accounted in DFT, namely the Tkatchenko-Scheffler method (with and without self-consistent screening), Grimme's methods (D2, D3(BJ)), and the vdW-DF method. Our results reveal that dispersion correction methods are essential in understanding these complex structures with van der Waals interactions and hydrogen bonding. The calculated ground state volumes and bulk moduli show that the performance of each method is not unique, and therefore a careful examination is mandatory for interpreting theoretical predictions. This work also emphasizes the importance of quasiparticle calculations in predicting the band gap, which is obtained here with the GW approximation. We find that the obtained band gaps are ranging from 4 to 7 eV for the different compounds, indicating their insulating nature. In addition, we show the essential role of quasiparticle band structure calculations to correlate the gap with the energetic properties.

  15. Preparation and study of properties of dispersed graphene oxide

    Directory of Open Access Journals (Sweden)

    Evgeniya Seliverstova

    2015-09-01

    Full Text Available Ability of graphene oxide to form stable dispersion in organic solvents was studied in this work. As it was shown, sonication of graphene leads to the decreas of the particle size. Stability of prepared graphene dispersions was studied upon measurements of distribution of number of the particles via size and change of optical density of the solutions with time. It was found that graphene oxide forms a more stable dispersion in tetrahydrofuran and dimethylformamide than in chloroform and acetone.

  16. Transient thermal effect, nonlinear refraction and nonlinear absorption properties of graphene oxide sheets in dispersion.

    Science.gov (United States)

    Zhang, Xiao-Liang; Liu, Zhi-Bo; Li, Xiao-Chun; Ma, Qiang; Chen, Xu-Dong; Tian, Jian-Guo; Xu, Yan-Fei; Chen, Yong-Sheng

    2013-03-25

    The nonlinear refraction (NLR) properties of graphene oxide (GO) in N, N-Dimethylformamide (DMF) was studied in nanosecond, picosecond and femtosecond time regimes by Z-scan technique. Results show that the dispersion of GO in DMF exhibits negative NLR properties in nanosecond time regime, which is mainly attributed to transient thermal effect in the dispersion. The dispersion also exhibits negative NLR in picosecond and femtosecond time regimes, which are arising from sp(2)- hybridized carbon domains and sp(3)- hybridized matrix in GO sheets. To illustrate the relations between NLR and nonlinear absorption (NLA), NLA properties of the dispersion were also studied in nanosecond, picosecond and femtosecond time regimes.

  17. Pulse splitting in nonlinear media with anisotropic dispersion properties

    DEFF Research Database (Denmark)

    Bergé, L.; Juul Rasmussen, J.; Schmidt, M.R.

    1998-01-01

    The nonlinear self-focusing of beams in media with anisotropic (mix-signed) dispersion is investigated. Theoretical predictions employing virial-type arguments and self-similar techniques suggest that a pulse propagating in a nonlinear medium with anisotropic dispersion will not collapse...

  18. Dispersal ability determines the scaling properties of species abundance distributions

    DEFF Research Database (Denmark)

    Borda-De-Água, Luís; Whittaker, Robert James; Cardoso, Pedro

    2017-01-01

    with computer simulations, low dispersal ability species generate a hump for intermediate abundance classes earlier than the distributions of high dispersal ability species. Importantly, when plotted as function of sample size, the raw moments of the SADs of arthropods have a power law pattern similar...

  19. Industrial and Commercial Property and the Dispersion of Assessed Valuation per Pupil

    Science.gov (United States)

    Boltz, Paul W.

    1973-01-01

    Examines the dispersion of assessed valuation per pupil in Illinois and evaluates some proposals that might reduce this dispersion. The major proposal considered by the author is removal of industrial and commercial property (I & C) from local rolls. The conclusion is drawn that removing I & C from the property tax base has little or no…

  20. Influence of dispersed particles on small and large deformation properties of concentrated caseinate composites

    NARCIS (Netherlands)

    Manski, J.M.; Kretzers, I.M.J.; Brenk, van S.; Goot, van der A.J.; Boom, R.M.

    2007-01-01

    Concentrated sodium caseinate composites (30% w/w in water), which contained either dispersed palm fat or glass spheres varying in size and surface properties were prepared in a Brabender Do-Corder kneader. The influence of the dispersed phase on the structural properties of the sodium caseinate

  1. Elemental mercury: Its unique properties affect its behavior and fate in the environment

    International Nuclear Information System (INIS)

    Gonzalez-Raymat, Hansell; Liu, Guangliang; Liriano, Carolina; Li, Yanbin; Yin, Yongguang; Shi, Jianbo; Jiang, Guibin; Cai, Yong

    2017-01-01

    Elemental mercury (Hg 0 ) has different behavior in the environment compared to other pollutants due to its unique properties. It can remain in the atmosphere for long periods of time and so can travel long distances. Through air-surface (e.g., vegetation or ocean) exchange (dry deposition), Hg 0 can enter terrestrial and aquatic systems where it can be converted into other Hg species. Despite being ubiquitous and playing a key role in Hg biogeochemical cycling, Hg 0 behavior in the environment is not well understood. The objective of this review is to provide a better understanding of how the unique physicochemical properties of Hg 0 affects its cycling and chemical transformations in different environmental compartments. The first part focuses on the fundamental chemistry of Hg 0 , addressing why Hg 0 is liquid at room temperature and the formation of amalgam, Hg halide, and Hg chalcogenides. The following sections discuss the long-range transport of Hg 0 as well as its redistribution in the atmosphere, aquatic and terrestrial systems, in particular, on the sorption/desorption processes that occur in each environmental compartment as well as the involvement of Hg 0 in chemical transformation processes driven by photochemical, abiotic, and biotic reactions. - Highlights: • Unique property of Hg 0 make it to behave differently with other toxic metals. • Hg 0 is considered the only global metal pollutant due to its uniqueness. • Hg 0 can be easily transformed and efficiently redistributed in the environments. - A better understanding of the properties and behavior of Hg 0 is the key to elucidate the biogeochemical cycling of mercury, a global pollutant in the environment.

  2. Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors

    Directory of Open Access Journals (Sweden)

    Prabir K. Dutta

    2012-04-01

    Full Text Available The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors.

  3. Selenoproteins-What unique properties can arise with selenocysteine in place of cysteine?

    Science.gov (United States)

    Arnér, Elias S J

    2010-05-01

    The defining entity of a selenoprotein is the inclusion of at least one selenocysteine (Sec) residue in its sequence. Sec, the 21st naturally occurring genetically encoded amino acid, differs from its significantly more common structural analog cysteine (Cys) by the identity of a single atom: Sec contains selenium instead of the sulfur found in Cys. Selenium clearly has unique chemical properties that differ from sulfur, but more striking are perhaps the similarities between the two elements. Selenium was discovered by Jöns Jacob Berzelius, a renowned Swedish scientist instrumental in establishing the institution that would become Karolinska Institutet. Written at the occasion of the bicentennial anniversary of Karolinska Institutet, this mini review focuses on the unique selenium-derived properties that may potentially arise in a protein upon the inclusion of Sec in place of Cys. With 25 human genes encoding selenoproteins and in total several thousand selenoproteins yet described in nature, it seems likely that the presence of that single selenium atom of Sec should convey some specific feature, thereby explaining the existence of selenoproteins in spite of demanding and energetically costly Sec-specific synthesis machineries. Nonetheless, most, if not all, of the currently known selenoproteins are also found as Cys-containing non-selenoprotein orthologues in other organisms, wherefore any potentially unique properties of selenoproteins are yet a matter of debate. The pK(a) of free Sec (approximately 5.2) being significantly lower than that of free Cys (approximately 8.5) has often been proposed as one of the unique features of Sec. However, as discussed herein, this pK(a) difference between Sec and Cys can hardly provide an evolutionary pressure for maintenance of selenoproteins. Moreover, the typically 10- to 100-fold lower enzymatic efficiencies of Sec-to-Cys mutants of selenoprotein oxidoreductases, are also weak arguments for the overall existence of

  4. Brush-Like Polymers: New Design Platforms for Soft, Dry Materials with Unique Property Relations

    Science.gov (United States)

    Daniel, William Francis McKemie, Jr.

    Elastomers represent a unique class of engineering materials due to their light weight, low cost, and desirable combination of softness (105 -107 Pa) and large extensibilities (up to 1000%). Despite these advantages, there exist applications that require many times softer modulus, greater extensibility, and stronger strain hardening for the purpose of mimicking the mechanical properties of systems such as biological tissues. Until recently, only liquid-filled gels were suitable materials for such applications, including soft robotics and implants. A considerable amount of work has been done to create gels with superior properties, but despite unique strengths they also suffer from unique weaknesses. This class of material displays fundamental limitations in the form of heterogeneous structures, solvent loss and phase transitions at extreme temperatures, and loss of liquid fraction upon high deformations. In gels the solvent fraction also introduces a large solvent/polymer interaction parameter which must be carefully considered when designing the final mechanical properties. These energetic considerations further exaggerate the capacity for inconstant mechanical properties caused by fluctuations of the solvent fraction. In order to overcome these weaknesses, a new platform for single component materials with low modulus (Standard networks have one major control factor outside of chemistry, the network stand length. Brush-like architectures are created from long strands with regularly grafted side chains creating three characteristic length scales which may be independently manipulated. In collaboration with M. Rubinstein, we have utilized bottlebrush polymer architectures (a densely grafted brush-like polymer) to experimentally verify theoretical predictions of disentangled bottlebrush melts. By attaching well-defined side chains onto long polymer backbones, individual polymer strands are separated in space (similar to dilution with solvent) accompanied by a

  5. Tungsten and molybdenum with oxide dispersion, production and properties

    International Nuclear Information System (INIS)

    Haerdtle, S.; Schmidberger, R.

    1989-01-01

    By the reaction spray process metal powders with dispersed metal oxides can be produced in one step. The systems investigated here are tungsten and molybdenum with 0,5% resp. 5% La 2 O 3 , Y 2 O 3 and ZrO 2 . The oxides with diameters below 0,5μm are finely dispersed within the metal powder particles. The sinterability of the powders depends on the oxide content. Maximum density at an oxide content of 0,5% is about 96% at a sintering temperature of 1600 0 C. The type of oxide influences the densification versus temperature but not the final density. 5 refs., 11 figs. (Author)

  6. High temperature mechanical properties of unirradiated dispersion strengthened copper

    International Nuclear Information System (INIS)

    Gentzbittel, J.M.; Rigollet, C.; Robert, G.

    1994-01-01

    Oxide Dispersion Strengthened (ODS) copper material, due to its excellent thermal conductivity associated with a high temperature strength is a candidate material for structural applications as divertor plasma facing components of thermonuclear fusion reactor. Tensile and creep results of oxide dispersion strengthened copper are presented. The most important features of ODS copper high temperature behaviour are the high strength corresponding to low creep rates, high stress creep rate dependence, a poor ductility and a brittleness which result in a premature creep fracture at high applied stress. (R.P.) 2 refs.; 6 figs

  7. Mechanical Properties of Carbon Nanotube/Polyurethane Nanocomposites via PPG Dispersion with MWCNTs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Won; Kim, Jong Seok [Chonbuk National University, Jeonju (Korea, Republic of)

    2015-12-15

    In order to improve the dispersity of nanofiller, polyurethane (PU) nanocomposites were manufactured via poly(propylene gylcol) (PPG) dispersion with MWCNTs prepared by using a ball mill shaker. MWCNTs could be functionalized by treating with the hydrogen peroxide (H{sub 2}O{sub 2}). Tensile strengths and elongations at break of PU/H{sub 2}O{sub 2} treated MWCNTs nanocomposites were enhanced compared to those of the PU/pristine MWCNTs nanocomposites. The good dispersion of MWCNTs shown in SEM images was obtained by the functionalization of MWCNTs surface. PU/carbon black (CB) composites showed no significant change in the tensile properties. The tensile properties of PU nanocomposites containing pristine MWCNTs or H{sub 2}O{sub 2} treated MWCNTs were enhanced with increasing dispersion time. As a result, it was certified that the enhanced dispersity of nanofiller brought the improvement of the tensile properties of the MWCNTs based PU nanocomposites.

  8. Dispersion relation for the 3. -->. 3 forward scattering amplitude and the generalized optical theorem. [Crossing properties, dispersion relations

    Energy Technology Data Exchange (ETDEWEB)

    Logunov, A A; Medvedev, B V; Mestvirishvili, M A; Pavlov, V P; Polivanov, M K; Sukhanov, A D [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Serpukhov. Inst. Fiziki Vysokikh Ehnergij

    1977-11-01

    Investigation of analytical structure of the three-particle forward scattering amplitude with respect to energy variable of one of particles is performed. The results obtained make it possible to draw the conclusions on crossing properties of the amplitude and to derive the generalized optical theorem relating the discontinuity of the amplitude to the distribution function of an inclusive process. For a special case when two of three particles are of zero mass, a dispersion relation is proved.

  9. Anomalous dispersion properties of TM waves in subwavelength metallic waveguides loaded by uniaxial metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guanghui, E-mail: wanggh@scnu.edu.cn; Lei, Yuandong; Zhang, Weifeng

    2015-02-20

    Dispersion properties of transverse magnetic (TM) waves in a subwavelength metallic waveguide loaded by uniaxial metamaterials are investigated, based on two kinds of uniaxial metamaterials with different orientations of optical axis. The numerical results show that the existence of fundamental TM{sub 0} mode and high-order TM modes in the waveguide system is dependent on the orientation of optical axis. In addition, their anomalous dispersion properties are clarified. When the orientation of optical axis is selected properly, there are two branches of dispersion curves for each high-order mode—one is normal dispersion and another belongs to anomalous dispersion, showing a transition from a backward wave to a forward one with the increase of working frequency. Moreover, the group velocity and energy flow distribution for TM{sub 1} mode are also demonstrated. These properties may have potential applications in optical information storage, integrated optics and nanophotonic devices. - Highlights: • Two kinds of subwavelength uniaxial metamaterial waveguides are constructed. • We demonstrate anomalous dispersion properties of transverse magnetic (TM) guided modes. • There are two branches of dispersion curves for high-order TM modes, showing a transition from a backward wave to a forward one. • Group velocity can approach to zero, having potential application in optical information storage. • Negative group velocity and energy flow distribution for TM modes are shown.

  10. Synthesis and magnetic properties of highly dispersed tantalum carbide nanoparticles decorated on carbon spheres

    CSIR Research Space (South Africa)

    Bhattacharjee, K

    2016-01-01

    Full Text Available The decoration of carbon spheres (CS) by highly dispersed tantalum carbide nanoparticles (TaC NPs) was achieved, for the first time by a unique carbothermal reduction method at 1350 °C for 30 min under reduced oxygen partial pressure. TaC NPs...

  11. Unique lasing mechanism of localized dispersive nanostructures in InAs/InGaAlAs quantum dash broad interband laser

    KAUST Repository

    Tan, C. L.

    2010-02-11

    The authors report on the nanowires-like and nanodots-like lasing behaviors in addition to multiple-wavelength interband transitions from InAs/InAlGaAs quantum dash (Qdash) lasers in the range of ~1550 nm. The presence of lasing actions simultaneously from two different dash ensembles, after postgrowth intermixing for crystalline quality improvement, indicate the absence of optical phonon emission due to the small variation in quantized interband transition energies. This effect is reproducible and shows different lasing characteristics from its quantum dot and quantum wire laser counterparts. Furthermore, the small energy spacing of only 25 nm (at center lasing wavelength of ~1550 nm) and the subsequent quenching of higher energy transition states at higher bias level in Qdash lasers suggest the absence of excited-state transition in highly inhomogeneous self-assembled Qdash structures. However, the appearance of a second lasing line in a certain range of high injection level, which is due to the presence of different sizes of dash assembles, corresponds to the transition from smaller size of Qdash ensembles in different planar active medium. This unique transition mechanism will affect the carrier dynamics, relaxation process in particular and further indicates localized finite carrier lifetime in all sizes of Qdash ensembles. These phenomena will lead to important consequences for the ground-state lasing efficiency and frequency modulation response of Qdash devices. In addition, these imply that proper manipulation of the Qdash ensembles will potentially result in localized nanolasers from individual ensemble and thus contributing towards enormously large envelope lasing coverage from semiconductor devices.

  12. Unique Intramolecular Electronic Communications in Mono-ferrocenylpyrimidine Derivatives: Correlation between Redox Properties and Structural Nature

    International Nuclear Information System (INIS)

    Xiang, Debo; Noel, Jerome; Shao, Huibo; Dupas, Georges; Merbouh, Nabyl; Yu, Hua-Zhong

    2015-01-01

    Highlights: • Unique intramolecular electronic communications (electron withdrawing and π-bond delocalization effects) exist in the mono-ferrocenylpyrimidine derivatives. • The redox potential shift correlates the pyrimidine ring torsion angle with the extent of electron delocalization. • The correlation between redox properties and structural nature in mono-ferrocenylpyrimidine derivatives is evident. - Abstract: The correlation between redox properties and structural nature in a complete set of mono-ferrocenylpyrimidine derivatives (2-ferrocenylpyrimidine, 2-FcPy; 4-ferrocenylpyrimidine, 4-FcPy; 5-ferrocenylpyrimidine, 5-FcPy) was evaluated by investigating the intramolecular electronic communications. Both conventional electrochemical measurements in organic solvents and thin-film voltammetric studies of these compounds were carried out. It was discovered that their formal potentials are significantly different from each other, and shift negatively in the order of 4-FcPy > 5-FcPy > 2-FcPy. This result suggests that the intramolecular electronic communication is dictated by the delocalization effect of the π-bonding systems in 2-FcPy, and that the electron-withdrawing effect of the nitrogen atoms in the pyrimidine ring plays the key role in 4-FcPy and 5-FcPy. The single crystal X-ray structure analyis and Density Functional Theory (DFT) calculation provided additional evidence (e.g., different torsion angles between the cyclopentadienyl and pyrimidine rings) to support the observed correlation between the redox properties and structural nature

  13. Unique self-assembly properties of a bridge-shaped protein dimer with quantum dots

    International Nuclear Information System (INIS)

    Wang, Jianhao; Jiang, Pengju; Gao, Liqian; Yu, Yongsheng; Lu, Yao; Qiu, Lin; Wang, Cheli; Xia, Jiang

    2013-01-01

    How protein–protein interaction affects protein–nanoparticle self-assembly is the key to the understanding of biomolecular coating of nanoparticle in biological fluids. However, the relationship between protein shape and its interaction with nanoparticles is still under-exploited because of lack of a well-conceived binding system and a method to detect the subtle change in the protein–nanoparticle assemblies. Noticing this unresolved need, we cloned and expressed a His-tagged SpeA protein that adopts a bridge-shaped dimer structure, and utilized a high-resolution capillary electrophoresis method to monitor assembly formation between the protein and quantum dots (QDs, 5 nm in diameter). We observed that the bridge-shaped structure rendered a low SpeA:QD stoichiometry at saturation. Also, close monitoring of imidazole (Im) displacement of surface-bound protein revealed a unique two-step process. High-concentration Im could displace surface-bound SpeA protein and form a transient QD–protein intermediate, through a kinetically controlled displacement process. An affinity-driven equilibrium step then followed, resulting in re-assembling of the QD–protein complex in about 1 h. Through a temporarily formed intermediate, Im causes a rearrangement of His-tagged proteins on the surface. Thus, our work showcases that the synergistic interplay between QD–His-tag interaction and protein–protein interaction can result in unique properties of protein–nanoparticle assembly for the first time

  14. Unique self-assembly properties of a bridge-shaped protein dimer with quantum dots

    Science.gov (United States)

    Wang, Jianhao; Jiang, Pengju; Gao, Liqian; Yu, Yongsheng; Lu, Yao; Qiu, Lin; Wang, Cheli; Xia, Jiang

    2013-09-01

    How protein-protein interaction affects protein-nanoparticle self-assembly is the key to the understanding of biomolecular coating of nanoparticle in biological fluids. However, the relationship between protein shape and its interaction with nanoparticles is still under-exploited because of lack of a well-conceived binding system and a method to detect the subtle change in the protein-nanoparticle assemblies. Noticing this unresolved need, we cloned and expressed a His-tagged SpeA protein that adopts a bridge-shaped dimer structure, and utilized a high-resolution capillary electrophoresis method to monitor assembly formation between the protein and quantum dots (QDs, 5 nm in diameter). We observed that the bridge-shaped structure rendered a low SpeA:QD stoichiometry at saturation. Also, close monitoring of imidazole (Im) displacement of surface-bound protein revealed a unique two-step process. High-concentration Im could displace surface-bound SpeA protein and form a transient QD-protein intermediate, through a kinetically controlled displacement process. An affinity-driven equilibrium step then followed, resulting in re-assembling of the QD-protein complex in about 1 h. Through a temporarily formed intermediate, Im causes a rearrangement of His-tagged proteins on the surface. Thus, our work showcases that the synergistic interplay between QD-His-tag interaction and protein-protein interaction can result in unique properties of protein-nanoparticle assembly for the first time.

  15. A Review on Graphene-Based Gas/Vapor Sensors with Unique Properties and Potential Applications

    Institute of Scientific and Technical Information of China (English)

    Tao Wang; Da Huang; Zhi Yang; Shusheng Xu; Guili He; Xiaolin Li; Nantao Hu; Guilin Yin; Dannong He; Liying Zhang

    2016-01-01

    Graphene-based gas/vapor sensors have attracted much attention in recent years due to their variety of structures, unique sensing performances, room-temperature working conditions, and tremendous application prospects, etc.Herein, we summarize recent advantages in graphene preparation, sensor construction, and sensing properties of various graphene-based gas/vapor sensors, such as NH3, NO2, H2, CO, SO2, H2S, as well as vapor of volatile organic compounds.The detection mechanisms pertaining to various gases are also discussed. In conclusion part, some existing problems which may hinder the sensor applications are presented. Several possible methods to solve these problems are proposed, for example, conceived solutions, hybrid nanostructures, multiple sensor arrays, and new recognition algorithm.

  16. Properties of sodium lignosulfonate as dispersant of coal water slurry

    International Nuclear Information System (INIS)

    Yang, Dongjie; Qiu, Xueqing; Zhou, Mingsong; Lou, Hongming

    2007-01-01

    In order to use lignosulfonates (a by-product of pulp and paper processes) as an effective dispersant of coal water slurry five purified sodium lignosulfonate (SL) samples with different molecular weights were prepared by fractionation using ultrafiltration and dialysis. The effect of SL on the apparent viscosity of coal water slurry (CWS) was investigated. The adsorption behavior of the SL on the coal water interface has much greater effect on the viscosity of coal water slurry. The higher adsorption amount and compact adsorption film of SL on the coal surface help reduce the viscosity of CWS, and the zeta potential is also an important factor, which is influenced by the sulfonic and carboxyl group contents of the lignosulfonate molecule. Furthermore, the SL with its molecular weight ranging from 10,000 to 30,000 has both a higher adsorbed amount and zeta potential on the coal surface and the best effect on reducing the viscosity of the coal water slurry

  17. Dispersion properties of three-layered orthotropic shells

    International Nuclear Information System (INIS)

    Markus, S.

    1995-01-01

    This paper studies the harmonic wave propagation in thick, cylindrical, three-layered shells of infinite length. Both the outer layers and the core are composites made of short strand fiberglass and polyester resin. The randomly oriented fibers were approximately in parallel planes to constitute a transversely isotropic fibre composite. The planes of isotropy in the outer layers are orthogonal to the plane of isotropy at the core. A closed form solution of the exact linear equations of elasticity in sought in terms of a Frobenius series. The influence of the core thickness on the dynamics of the wave motion is estimated from numerically computed dispersion curves. Asymmetric wave motion is given prime consideration and the different types of waves which can occur are identified over a wide range of wave numbers

  18. Properties of U3Si2-Al dispersion fuel element and its application

    International Nuclear Information System (INIS)

    Yin Changgeng

    2001-01-01

    The properties of U 3 Si 2 fuel and U 3 Si 2 -Al dispersion fuel element are introduced, which include U-loading; the banding quality, U-homogeneity and 'dog-bone' phenomenon, the minimum thickness of cladding and the corrosion performances. The fabrication technique of fuel elements, NDT for fuel plates, assemble technique of fuel elements and the application of U 3 Si 2 -Al dispersion fuel elements in the world are introduced

  19. Plasma influence on the dispersion properties of finite-length, corrugated waveguides

    OpenAIRE

    Shkvarunets, A.; Kobayashi, S.; Weaver, J.; Carmel, Y.; Rodgers, J.; Antonsen, T.; Granatstein, V.L.; Destler, W.W.; Ogura, K.; Minami, K.

    1996-01-01

    We present an experimental study of the electromagnetic properties of transverse magnetic modes in a corrugated-wall cavity filled with a radially inhomogeneous plasma. The shifts of the .resonant frequencies of a finite-length, corrugated cavity were measured as a function of the background plasma density and the dispersion diagram was reconstructed up to a peak plasma density of 1012 em - 3. Good agreement with a calculated dispersion diagram is obtained for plasma densities below 5 X 1011 ...

  20. Plasma influence on the dispersion properties of finite-length, corrugated waveguides

    Science.gov (United States)

    Shkvarunets, A.; Kobayashi, S.; Weaver, J.; Carmel, Y.; Rodgers, J.; Antonsen, T. M., Jr.; Granatstein, V. L.; Destler, W. W.; Ogura, K.; Minami, K.

    1996-03-01

    We present an experimental study of the electromagnetic properties of transverse magnetic modes in a corrugated-wall cavity filled with a radially inhomogeneous plasma. The shifts of the resonant frequencies of a finite-length, corrugated cavity were measured as a function of the background plasma density and the dispersion diagram was reconstructed up to a peak plasma density of 1012 cm-3. Good agreement with a calculated dispersion diagram is obtained for plasma densities below 5×1011 cm-3.

  1. Experimental study on the dispersion properties of cusptron structure

    International Nuclear Information System (INIS)

    Choe, J.Y.; Crosby, H.; Jablon, D.G.; Krall, A.D.; Namkung, W.

    1984-01-01

    One of the promising devices that generates high frequency microwaves is the cusptron, where the fast rotating electron beam interacts with the high muthal (iota>1) waveguide mode, thereby producing multiples of the cyclotron frequency (iotaω/sub c/). In order to encourage the chosen azimuthal perturbation, it is necessary to structure the wall in a magnetron-like shape. In particular, the authors consider the structure where the outer wall is radially cut out to make multiple vane-like resonators. With these interruptions, it obvious that there exist strong couplings among the muthal space harmonics, iota n in the cusptron device. The mode is characterized by the axial wave number, k, the primary azimuthal mode number iota, which indicates the phase difference between adjacent segments, and whether it is TE or TM. Recently, a rigorous numerical method has been devised to determine the cusptron structure. This method uses the orthonormal mode expansions both in the interaction space and the resonators to assure the point-by-point match of the fields. The method also finds the distribution of the harmonics iota n as well, that serves as a signature of the particular mode. In the present study, the authors experimentally investigate the dispersion characteristics of the cusptron, and compare the results with the theory

  2. Weak unique continuation property and a related inverse source problem for time-fractional diffusion-advection equations

    Science.gov (United States)

    Jiang, Daijun; Li, Zhiyuan; Liu, Yikan; Yamamoto, Masahiro

    2017-05-01

    In this paper, we first establish a weak unique continuation property for time-fractional diffusion-advection equations. The proof is mainly based on the Laplace transform and the unique continuation properties for elliptic and parabolic equations. The result is weaker than its parabolic counterpart in the sense that we additionally impose the homogeneous boundary condition. As a direct application, we prove the uniqueness for an inverse problem on determining the spatial component in the source term by interior measurements. Numerically, we reformulate our inverse source problem as an optimization problem, and propose an iterative thresholding algorithm. Finally, several numerical experiments are presented to show the accuracy and efficiency of the algorithm.

  3. Dispersion of conservative properties for SGD effects by numerical modeling

    Science.gov (United States)

    Gallegos, G.; Marino-Tapia, I.; Enriquez, C.

    2013-05-01

    The submarine groundwater discharges around de coasts of theYucatán Peninsula are very common because of its karstic nature. These discharges of fresh water into the sea can change the thermohaline conditions of the region. There are several studies that demonstrate that point submarine groundwater discharges can change the superficial temperature and haline conditions near the point-SGD. Furthermore, there is evidence that considerable concentrations of nutrients are transported to the sea via SGDs. In order to quantify the area of influence of a point-SGD and the ability of the coastal system to dissipate the ground water, this study presents a numerical simulation of a point-SGD on the north coast of Yucatán, Dzilam Bravo. Teh flow recorded for this SGD is ~1m^3/s and it is located 200m offshore in waters of less than 2m detph.. The numerical simulation was carried out in the model DELFT-3D which has been calibrated with water level and hydrodynamics data for the region with a grid of 486 x 243 nodes that cover an area of 6 km alongshore by 2 km crosshore with a resolution of 14 m. Three ideal numerical scenarios were simulated: only wind forcing, only tidal forcing and wind-tide forcing. The real cases are for two different wind conditions, the first is a southeast wind, and the second is a breeze with an easterly component; the dominant winds in the region are easterly. Seasonal variation was also simulated; the two conditions that exist in the region are the rainy and dry seasons. The extreme events of ENSO and northerly storms locally known as "nortes" were also simulated. The results of the ideal set of scenarios shows wind as the principal forcing for dispersion and it governs the direction of the salinity gradient. The seasonal variations show that the area of influence in terms of salinity is also a function of the contrast between fresh and sea water, and finally the set of extreme condition simulations shows, in case of the northerly storms, that the

  4. Dodecylamine functionalization of carbon nanotubes to improve dispersion, thermal and mechanical properties of polyethylene based nanocomposites

    Science.gov (United States)

    Ferreira, F. V.; Franceschi, W.; Menezes, B. R. C.; Brito, F. S.; Lozano, K.; Coutinho, A. R.; Cividanes, L. S.; Thim, G. P.

    2017-07-01

    This study presents the effect of dodecylamine (DDA) functionalization of carbon nanotubes (CNTs) on the thermo-physical and mechanical properties of high-density polyethylene (HDPE) based composites. Here, we showed that the functionalization with DDA improved the dispersion of the CNTs as well as the interfacial adhesion with the HDPE matrix via non-covalent interactions. The better dispersion and interaction of CNT in the HDPE matrix as a function of the surface chemistry was correlated with the improved thermo-physical and mechanical properties.

  5. Enhanced dispersion of carbon nanotubes in hyperbranched polyurethane and properties of nanocomposites

    International Nuclear Information System (INIS)

    Rana, Sravendra; Karak, Niranjan; Cho, Jae Whan; Kim, Young Ho

    2008-01-01

    Hyperbranched polyurethane (HBPU) nanocomposites with multi-walled carbon nanotubes (MWNTs) were prepared by in situ polymerization on the basis of poly(ε-caprolactone)diol as the soft segment, 4,4'-methylene bis(phenylisocyanate) as the hard segment, and castor oil as the multifunctional group for the hyperbranched structure. A dominant improvement in the dispersion of MWNTs in the HBPU matrix was found, and good solubility of HBPU-MWNT nanocomposites in organic solvents was shown. Due to the well-dispersed MWNTs, the nanocomposites resulted in achieving excellent shape memory properties as well as enhanced mechanical properties compared to pure HBPU.

  6. Effect of exchange correlation potential on dispersion properties of lower hybrid wave in degenerate plasma

    Science.gov (United States)

    Rimza, Tripti; Sharma, Prerana

    2017-05-01

    The dispersion properties of lower hybrid wave are studied in electron-iondegenerate plasma with exchange effect in non-relativistic regime. It is found that the combined effect of Bohm potential and exchange correlation potential significantly modifies the dispersion properties of lower hybrid wave. The graphical results explicitly show the influence of degeneracy pressure, Bohm force and exchange correlation potential on the frequency of the lower hybrid mode. Present work should be of relevance for the dense astrophysical environments like white dwarfs and for laboratory experiments.

  7. Dispersion properties of ducted whistlers, generated by lightning discharge

    Directory of Open Access Journals (Sweden)

    D. L. Pasmanik

    2005-06-01

    Full Text Available Whistler-mode wave propagation in magnetospheric ducts of enhanced cold plasma density is studied. The case of the arbitrary ratio of the duct radius to the whistler wavelength is considered, where the ray-tracing method is not applicable. The set of duct eigenmodes and their spatial structure are analysed and dependencies of eigenmode propagation properties on the duct characteristics are studied. Special attention is paid to the analysis of the group delay time of one-hop propagation of the whistler wave packet along the duct. We found that, in contrast to the case of a wide duct, the group delay time in a rather narrow duct decreases as the eigenmode number increases. The results obtained are suggested for an explanation of some types of multi-component whistler signals.

  8. Dispersion properties of plasma cladded annular optical fiber

    Science.gov (United States)

    KianiMajd, M.; Hasanbeigi, A.; Mehdian, H.; Hajisharifi, K.

    2018-05-01

    One of the considerable problems in a conventional image transferring fiber optic system is the two-fold coupling of propagating hybrid modes. In this paper, using a simple and practical analytical approach based on exact modal vectorial analysis together with Maxwell's equations, we show that applying plasma as a cladding medium of an annular optical fiber can remove this defect of conventional fiber optic automatically without any external instrument as the polarization beam splitter. Moreover, the analysis indicates that the presence of plasma in the proposed optical fiber could extend the possibilities for controlling the propagation property. The proposed structure presents itself as a promising route to advanced optical processing and opens new avenues in applied optics and photonics.

  9. Probing the Unique Role of Gallium in Amorphous Oxide Semiconductors through Structure-Property Relationships

    Energy Technology Data Exchange (ETDEWEB)

    Moffitt, Stephanie L.; Zhu, Qimin; Ma, Qing; Falduto, Allison F.; Buchholz, D. Bruce; Chang, Robert P.H.; Mason, Thomas O.; Medvedeva, Julia E.; Marks, Tobin J.; Bedzyk, Michael J. (NWU); (MUST)

    2017-09-01

    This study explores the unique role of Ga in amorphous (a-) In[BOND]Ga[BOND]O oxide semiconductors through combined theory and experiment. It reveals substitutional effects that have not previously been attributed to Ga, and that are investigated by examining how Ga influences structure–property relationships in a series of pulsed laser deposited a-In[BOND]Ga[BOND]O thin films. Element-specific structural studies (X-ray absorption and anomalous scattering) show good agreement with the results of ab initio molecular dynamics simulations. This structural knowledge is used to understand the results of air-annealing and Hall effect electrical measurements. The crystallization temperature of a-IO is shown to increase by as much as 325 °C on substituting Ga for In. This increased thermal stability is understood on the basis of the large changes in local structure that Ga undergoes, as compared to In, during crystallization. Hall measurements reveal an initial sharp drop in both carrier concentration and mobility with increasing Ga incorporation, which moderates at >20 at% Ga content. This decline in both the carrier concentration and mobility with increasing Ga is attributed to dilution of the charge-carrying In[BOND]O matrix and to increased structural disorder. The latter effect saturates at high at% Ga.

  10. Unique chloride-sensing properties of WNK4 permit the distal nephron to modulate potassium homeostasis.

    Science.gov (United States)

    Terker, Andrew S; Zhang, Chong; Erspamer, Kayla J; Gamba, Gerardo; Yang, Chao-Ling; Ellison, David H

    2016-01-01

    Dietary potassium deficiency activates thiazide-sensitive sodium chloride cotransport along the distal nephron. This may explain, in part, the hypertension and cardiovascular mortality observed in individuals who consume a low-potassium diet. Recent data suggest that plasma potassium affects the distal nephron directly by influencing intracellular chloride, an inhibitor of the with-no-lysine kinase (WNK)-Ste20p-related proline- and alanine-rich kinase (SPAK) pathway. As previous studies used extreme dietary manipulations, we sought to determine whether the relationship between potassium and NaCl cotransporter (NCC) is physiologically relevant and clarify the mechanisms involved. We report that modest changes in both dietary and plasma potassium affect NCC in vivo. Kinase assay studies showed that chloride inhibits WNK4 kinase activity at lower concentrations than it inhibits activity of WNK1 or WNK3. Also, chloride inhibited WNK4 within the range of distal cell chloride concentration. Mutation of a previously identified WNK chloride-binding motif converted WNK4 effects on SPAK from inhibitory to stimulatory in mammalian cells. Disruption of this motif in WNKs 1, 3, and 4 had different effects on NCC, consistent with the three WNKs having different chloride sensitivities. Thus, potassium effects on NCC are graded within the physiological range, which explains how unique chloride-sensing properties of WNK4 enable it to mediate effects of potassium on NCC in vivo. Copyright © 2015 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  11. Manipulating dispersion and distribution of graphene in PLA through Novel Interface Engineering for improved conductive properties

    Science.gov (United States)

    This study aimed to enhance the conductive properties of PLA nanocomposite by controlling the dispersion and distribution of graphene within the minor phase of the polymer blend. Functionalized graphene (f-GO) was achieved by reacting graphene oxide (GO) with various silanes under the aid of an ioni...

  12. Rheological properties of dispersions of enzymatically cross-linked apo-α-lactalbumin

    NARCIS (Netherlands)

    Saricay, Yunus; Wierenga, Peter A.; Vries, de Renko

    2016-01-01

    The enzymatic cross-linking of apo-α-lactalbumin (α-LA) with horseradish peroxidase (HRP) leads to the formation of hydrophilic protein aggregates with controlled size and architecture. We explore the rheological properties of dispersions of these HRP-cross-linked α-LA aggregates with a

  13. Tri-block copolymers with mono-disperse crystallizable diamide segments: synthesis, analysis and rheological properties

    NARCIS (Netherlands)

    Araichimani, A.; Gaymans, R.J.

    2008-01-01

    Tri-block copolymers with polyether mid-segments and mono-disperse amide end segments were synthesized, analyzed and some properties studied. The end segment was an aromatic diamide (diaramide, TΦB). The polyether mid-segment was a difunctional poly(tetramethylene oxide) (PTMO, 1000 and 2900 g/mol).

  14. Probing the dispersion properties of 1D nanophotonic waveguides with far-field Fourier optics

    DEFF Research Database (Denmark)

    Le Thomas, N.; Jágerská, J.; Houdré, R.

    2008-01-01

    We present an advanced Fourier space imaging technique to probe guided light in nanophotonic structures with an effective numerical aperture of 2.5. This superresolution technique allows us to successfully investigate the dispersive properties of 1D nanowaveguides such as photonic crystal W1...

  15. The unique genomic properties of sex-biased genes: Insights from avian microarray data

    Directory of Open Access Journals (Sweden)

    Webster Matthew T

    2008-03-01

    Full Text Available Abstract Background In order to develop a framework for the analysis of sex-biased genes, we present a characterization of microarray data comparing male and female gene expression in 18 day chicken embryos for brain, gonad, and heart tissue. Results From the 15982 significantly expressed coding regions that have been assigned to either the autosomes or the Z chromosome (12979 in brain, 13301 in gonad, and 12372 in heart, roughly 18% were significantly sex-biased in any one tissue, though only 4 gene targets were biased in all tissues. The gonad was the most sex-biased tissue, followed by the brain. Sex-biased autosomal genes tended to be expressed at lower levels and in fewer tissues than unbiased gene targets, and autosomal somatic sex-biased genes had more expression noise than similar unbiased genes. Sex-biased genes linked to the Z-chromosome showed reduced expression in females, but not in males, when compared to unbiased Z-linked genes, and sex-biased Z-linked genes were also expressed in fewer tissues than unbiased Z coding regions. Third position GC content, and codon usage bias showed some sex-biased effects, primarily for autosomal genes expressed in the gonad. Finally, there were several over-represented Gene Ontology terms in the sex-biased gene sets. Conclusion On the whole, this analysis suggests that sex-biased genes have unique genomic and organismal properties that delineate them from genes that are expressed equally in males and females.

  16. Uniqueness of Gibbs states and global Markov property for Euclidean fields

    International Nuclear Information System (INIS)

    Albeverio, S.; Hoeegh-Krohn, R.

    1981-01-01

    The authors briefly discuss the proof of the uniqueness of solutions of the DLR equations (uniqueness of Gibbs states) in the class of regular generalized random fields (in the sense of having second moments bounded by those of some Euclidean field), for the Euclidean fields with trigonometric interaction. (Auth.)

  17. Properties of aqueous dispersion of chitosan and chondroitin sulfate complex derived from aquatic organisms

    Directory of Open Access Journals (Sweden)

    Novikov V. Yu.

    2016-09-01

    Full Text Available Investigation of production of chondroitin sulfate, chitosan and polyelectrolyte complexes based on them received from the local marine raw materials is relevant from the point of view of developing a comprehensive waste-free technology for natural raw materials processing. The objects of study are chitosan derived from the shell of the Kamchatka crab Paralithodes camtschaticus and chondroitin sulfate derived from cartilage of salmon Salmon salar. To determine the surface tension of polyelectrolyte complex solutions and dispersions the Wilhelmy method has been used, the effective radius of particle dispersion has been calculated by light scattering, measurements of effective viscosity have been carried out under shear deformation. The conditions of formation, surface and rheological properties of the chitosan and chondroitin sulfate complex extracted from aquatic organisms in the Barents Sea have been studied. Obtaining conditions and molar ratios of these polyelectrolytes in which the aqueous dispersion of the complex remains stable for a long time have been established. It has been found that by addition of chondroitin sulfate solution to chitosan solution in molar ratios of 1 : 3; 1 : 6 the dispersion of the polyelectrolyte complex stable for 2 to 3 days has been formed. The polyelectrolyte complex dispersions behave as non-Newtonian pseudoplastic liquid. When the molar ratio of the mixed solution is 1 : 1 (regardless of the sequence of mixing suspension of the polyelectrolyte complex has been formed, then there is precipitation. Equilibrium surface tension of the aqueous dispersion of the polyelectrolyte complex is higher than that of solutions of chondroitin sulfate and chitosan. The effective radius of particles in the complex dispersion has been determined. The effective radius of the particles in the complex dispersion depends on the molar ratio of chondroitin sulfate : chitosan. A qualitative scheme of formation of polyelectrolyte

  18. Photophysical and adsorption properties of pyronin B in natural bentonite clay dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Rostami, Mohammad Reza [Department of Chemistry, Faculty of Sciences, Atatürk University, 25240, Erzurum (Turkey); Kaya, Mehmet [Recep Tayyip Erdoğan University, Faculty of Arts and Sciences, 53100 Rize (Turkey); Gür, Bahri; Onganer, Yavuz [Department of Chemistry, Faculty of Sciences, Atatürk University, 25240, Erzurum (Turkey); Meral, Kadem, E-mail: kademm@atauni.edu.tr [Department of Chemistry, Faculty of Sciences, Atatürk University, 25240, Erzurum (Turkey)

    2015-12-30

    Graphical abstract: The molecular aggregation of PyB in bentonite aqueous dispersion is observed by using molecular absorption spectrum. - Highlights: • Molecular behavior of PyB adsorbed on bentonite was spectroscopically followed. • H-aggregates of PyB in bentonite aqueous dispersion were formed. • The adsorption characteristics of PyB on bentonite particles were determined. - Abstract: The present study focused on the adsorption and photophysical properties of pyronin B (PyB) in bentonite aqueous dispersion. The photophysical properties of PyB in the aqueous dispersion were studied by using UV–vis absorption, steady-state and time-resolved fluorescence spectroscopy techniques. In this concept, the interaction of the dye with bentonite particles in the aqueous dispersion was spectroscopically followed depending on certain parameters such as interaction time, pH and the dye concentration. Obtained spectral data revealed that the aggregate structures (H-type) of PyB in the aqueous dispersion were formed in the dye concentration range studied. The non-fluorescence nature of H-aggregates and the clay minerals governed the fluorescence property of PyB. The mentioned non-radiative processes caused the fluorescence lifetime of the dye to decrease compared to that in water. The adsorption process of PyB on bentonite was examined depending on contact time and initial adsorbate concentration. An adsorption isotherm was good-fitted by the Freundlich model with a linear regression correlation value of 0.999. The adsorption of PyB on bentonite particles was in agreement with pseudo second-order kinetics.

  19. Impact of ultrasonic assisted triangular lattice like arranged dispersion of nanoparticles on physical and mechanical properties of epoxy-TiO2 nanocomposites.

    Science.gov (United States)

    Goyat, M S; Ghosh, P K

    2018-04-01

    Emerging ex-situ technique, ultrasonic dual mixing (UDM) offers unique and hitherto unapproachable opportunities to alter the physical and mechanical properties of polymer nanocomposites. In this study, triangular lattice-like arranged dispersion of TiO 2 nanoparticles (average size ∼ 48 nm) in the epoxy polymer has been attained via concurrent use of a probe ultra-sonicator and 4 blades pitched impeller which collectively named as UDM technique. The UDM processing of neat epoxy reveals the generation of triangular lattice-like arranged nanocavities with nanoscale inter-cavity spacing. The UDM processing of epoxy-TiO 2 nanocomposites reveals two unique features such as partial and complete entrapping of the nanoparticles by the nanocavities leading the arranged dispersion of particles in the epoxy matrix. Pristine TiO 2 nanoparticles were dispersed in the epoxy polymer at loading fractions of up to 20% by weight. The results display that the arranged dispersion of nanoparticles is very effective at enhancing the glass transition temperature (T g ) and tensile properties of the epoxy at loading fractions of 10 wt%. We quantify a direct relationship among three important parameters such as nanoparticle content, cluster size, and inter-particle spacing. Our results offer a novel understanding of these parameters on the T g and tensile properties of the epoxy nanocomposites. The tensile fracture surfaces revealed several toughening mechanisms such as particle pull-out, plastic void growth, crack deflection, crack bridging and plastic deformation. We show that a strong nanoparticle-matrix interface led to the enhanced mechanical properties due to leading toughening mechanisms such as crack deflection, plastic deformation and particle pull-out. We showed that the UDM has an inordinate prospective to alter the dispersion state of nanoparticles in viscous polymer matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Stable dispersion of nanodiamonds in oil and their tribological properties as lubricant additives

    Science.gov (United States)

    Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku; Rhee, Chang Kyu

    2017-09-01

    Nanodiamonds (NDs) are innovative additives when a combination of mechanical, thermal, tribological, and dielectric properties are required. In this study, a surface modification with oleic acid (OA) is developed for the deaggregation and prolonged dispersion of NDs in oil, and the effect of the NDs as lubricant additives on the tribological properties of a steel substrate is investigated. The OA renders the ND surface hydrophobic and decreases the average particle size from 268.6 to 20.1 nm. The OA-treated NDs exhibit very stable dispersion in oil even after more than 10 days, compared with the untreated NDs. From the analyses of the friction coefficient, wear loss, and worn surfaces using a ball-on-disk wear test, it is concluded that a 0.05 wt% addition of OA-treated NDs in oil lubricant provides excellent friction and anti-wear properties with the friction coefficient being reduced by 23%.

  1. Importance of intrinsic properties of dense caseinate dispersions for structure formation.

    Science.gov (United States)

    Manski, Julita M; van Riemsdijk, Lieke E; van der Goot, Atze J; Boom, Remko M

    2007-11-01

    Rheological measurements of dense calcium caseinate and sodium caseinate dispersions (> or =15%) provided insight into the factors determining shear-induced structure formation in caseinates. Calcium caseinate at a sufficiently high concentration (30%) was shown to form highly anisotropic structures during shearing and concurrent enzymatic cross-linking. In contrast, sodium caseinate formed isotropic structures using similar processing conditions. The main difference between the two types of caseinates is the counterion present, and as a consequence, the size of structural elements and their interactions. The rheological behavior of calcium caseinate and sodium caseinate reflected these differences, yielding non-monotonic and shear thinning flow behavior for calcium caseinate whereas sodium caseinate behaved only slightly shear thinning. It appears that the intrinsic properties of the dense caseinate dispersions, which are reflected in their rheological behavior, affect the structure formation that was found after applying shear. Therefore, rheological measurements are useful to obtain an indication of the structure formation potential of caseinate dispersions.

  2. Unique Nanoparticle Optical Properties Confound Fluorescent Based Assays Widely Employed in Their In Vitro Toxicity Screening and Ranking

    Science.gov (United States)

    Nanoparticles (NPs) are novel materials having at least one dimension less than 100 nm and display unique physicochemical properties due to their nanoscale size. An emphasis has been placed on developing high throughput screening (HTS) assays to characterize and rank the toxiciti...

  3. Unique Nanoparticle Properties Confound Fluorescent Based Assays Widely Employed in Their In Vitro Toxicity Testing and Ranking

    Science.gov (United States)

    Nanomaterials are a diverse collection of novel materials that exhibit at least one dimension less than 100 nm and display unique chemical and physical properties due to their nanoscale size. An emphasis has been put on developing high throughput screening (HTS) assays to charac...

  4. Cole-Cole Measurement of Dispersion Properties for Quality Evaluation of Red Wine

    Science.gov (United States)

    Watanabe, Kota; Taka, Yoshinori; Fujiwara, Osamu

    2009-01-01

    In order to evaluate the quality of red wine, measurement of the complex relative permittivity was conducted in the frequency range from 100 MHz to 40 GHz with a network analyzer. Results showed that the Cole-Cole plot of red wine consists of a semicircle at frequencies above 1 GHz and a straight line at frequencies below 1 GHz, which come from the dispersion properties for the water solution of alcohol and ingredients peculiar to red wine, respectively. Based on the Cole-Cole plots measured for seven kinds of red wines made from the same brand of Merlot in different production years, we estimated Debye dispersion parameters to reveal that the alcohol concentration and ingredient property can simultaneously be evaluated from the parameters for the semicircle and straight line, respectively.

  5. Properties of alginate fiber spun-dyed with fluorescent pigment dispersion.

    Science.gov (United States)

    Wang, Ping; Tawiah, Benjamin; Tian, Anli; Wang, Chunxia; Zhang, Liping; Fu, Shaohai

    2015-03-15

    Spun-dyed alginate fiber was prepared by the spun-dyeing method with the mixture of fluorescent pigment dispersion and sodium alginate fiber spinning solution, and its properties were characterized by SEM, TGA, DSC, and XRD. The results indicate that fluorescent pigment dispersion prepared with esterified poly (styrene-alt maleic acid) had excellent compatibility with sodium alginate fiber spinning solution, and small amount of fluorescent pigment could reduce the viscosity of spun-dyed spinning solutions. SEM photo of spun-dyed alginate fiber indicated that fewer pigment particles deposited on its surface. TGA, DSC, and XRD results suggested that thermal properties and crystal phase of spun-dyed alginate fibers had slight changes compared to the original alginate fibers. The fluorescence intensity of spun-dyed alginate fiber reached its maximum when the content of fluorescent pigment was 4%. The spun-dyed alginate fiber showed excellent rubbing and washing fastness. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Unique functional properties of somatostatin-expressing GABAergic neurons in mouse barrel cortex.

    NARCIS (Netherlands)

    Gentet, L.J.; Kremer, Y.; Taniguchi, H.; Huang, Z.J.; Staiger, J.F.; Petersen, C.C.H.

    2012-01-01

    Neocortical GABAergic neurons have diverse molecular, structural and electrophysiological features, but the functional correlates of this diversity are largely unknown. We found unique membrane potential dynamics of somatostatin-expressing (SOM) neurons in layer 2/3 of the primary somatosensory

  7. Some general properties of stimulated Raman propagation with pump depletion, transiency and dispersion

    International Nuclear Information System (INIS)

    Shore, B.W.; Lowder, S.; Johnson, M.A.

    1991-01-01

    This note considers some of the properties of the Stokes pulse that grows from a specified seed pulse in the presence of a strong pump pulse as it propagates through a dispersive atomic vapor. We first present an generic dimensionless form for the coupled equations that govern the propagation of pump and Stokes fields or collinear plane-wave pulses. By treating the two fields we permit pump depletion. We include transient atomic response (as embodied in the Raman coherence), but neglect changes in atomic populations. (Thus our equations pertain to the regime in which atoms are more numerous than photons). The equations employ a gain length, a dispersion time τ dis , and a Raman coherence time (or memory time) τ R as basic parameters: these two times, together with a single-photon stationary-atom detuning Δ, subsume the details of a particular atomic Raman transition and particular operating conditions. (The effects of Doppler shifts enters the equations through the coherence time). We discuss some general properties of these generic Raman propagation equations, and present illustrations of their solutions in the absence of dispersion. We comment on departures from exponential growth. We than show examples of behavior when dispersion is present and the pump pulse has a bandwidth that exceeds the transform limit. The illustrations presented here do not pertain to any specific atom (i.e. specific wavelengths and oscillator strengths) or to specific experimental conditions (i.e. number densities and pulse intensities). To permit the connection between the present generic results and particular experiments we conclude by providing expressions for the gain length and dispersion time in terms of atomic number density, polarizabilities, oscillator strengths, statistical weights, transition frequencies, and polarization directions. 11 figs

  8. Exploiting Unique Structural and Functional Properties of Malarial Glycolytic Enzymes for Antimalarial Drug Development

    Directory of Open Access Journals (Sweden)

    Asrar Alam

    2014-01-01

    Full Text Available Metabolic enzymes have been known to carry out a variety of functions besides their normal housekeeping roles known as “moonlighting functions.” These functionalities arise from structural changes induced by posttranslational modifications and/or binding of interacting proteins. Glycolysis is the sole source of energy generation for malaria parasite Plasmodium falciparum, hence a potential pathway for therapeutic intervention. Crystal structures of several P. falciparum glycolytic enzymes have been solved, revealing that they exhibit unique structural differences from the respective host enzymes, which could be exploited for their selective targeting. In addition, these enzymes carry out many parasite-specific functions, which could be of potential interest to control parasite development and transmission. This review focuses on the moonlighting functions of P. falciparum glycolytic enzymes and unique structural differences and functional features of the parasite enzymes, which could be exploited for therapeutic and transmission blocking interventions against malaria.

  9. Electrical percolation, morphological and dispersion properties of MWCNT/PMMA nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Paulo Henrique da Silva Leite; Marchesin, Marcel Silva; Morales, Ana Rita; Bartoli, Julio Roberto, E-mail: piyke.coelho@gmail.com [Universidade de Campinas (UNICAMP), SP (Brazil). Escola de Engenharia Quimica

    2014-08-15

    Nanocomposites of poly (methyl methacrylate) (PMMA) and carbon nanotubes have a high potential for applications where conductivity and low specific weight are required. This piece of work concerns investigations of the level of dispersion and morphology on the electrical properties of in situ polymerized nanocomposites in different concentrations of multi-walled carbon nanotubes (MWCNT) in a PMMA matrix. The electrical conductivity was measured by the four point probe. The morphology and dispersion was analyzed by Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). The correlation between electrical conductivity and the MWCNT amount, presented a typical percolation behavior, whose electrical percolation threshold determined by power law relationship was 0.2 vol. (%) The exponent t from the percolation power law indicated the formation of a 3D network of randomly arranged MWCNT. SAXS detected that the structures are intermediate to disks or spheres indicating fractal geometry for the MWCNT aggregates instead of isolated rods. HR-TEM images allowed us to observe the MWCNT individually dispersed into the matrix, revealing their distribution without preferential space orientation and absence of significant damage to the walls. The combined results of SAXS and HR-TEM suggest that MWCNT into the polymeric matrix might present interconnected aggregates and some dispersed single structures. (author)

  10. Electrical percolation, morphological and dispersion properties of MWCNT/PMMA nanocomposites

    International Nuclear Information System (INIS)

    Coelho, Paulo Henrique da Silva Leite; Marchesin, Marcel Silva; Morales, Ana Rita; Bartoli, Julio Roberto

    2014-01-01

    Nanocomposites of poly (methyl methacrylate) (PMMA) and carbon nanotubes have a high potential for applications where conductivity and low specific weight are required. This piece of work concerns investigations of the level of dispersion and morphology on the electrical properties of in situ polymerized nanocomposites in different concentrations of multi-walled carbon nanotubes (MWCNT) in a PMMA matrix. The electrical conductivity was measured by the four point probe. The morphology and dispersion was analyzed by Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). The correlation between electrical conductivity and the MWCNT amount, presented a typical percolation behavior, whose electrical percolation threshold determined by power law relationship was 0.2 vol. (%) The exponent t from the percolation power law indicated the formation of a 3D network of randomly arranged MWCNT. SAXS detected that the structures are intermediate to disks or spheres indicating fractal geometry for the MWCNT aggregates instead of isolated rods. HR-TEM images allowed us to observe the MWCNT individually dispersed into the matrix, revealing their distribution without preferential space orientation and absence of significant damage to the walls. The combined results of SAXS and HR-TEM suggest that MWCNT into the polymeric matrix might present interconnected aggregates and some dispersed single structures. (author)

  11. Influence of MWCNT/surfactant dispersions on the mechanical properties of Portland cement pastes

    Science.gov (United States)

    Rodríguez, B.; Quintero, J. H.; Arias, Y. P.; Mendoza-Reales, O. A.; Ochoa-Botero, J. C.; Toledo-Filho, R. D.

    2017-12-01

    This work studies the reinforcing effect of Multi Walled Carbon Nanotubes (MWCNT) on cement pastes. A 0.35% solid concentration of MWCNT in powder was dispersed in deionized water with sodium dodecyl sulfate (cationic surfactant), cetylpyridinium chloride (anionic surfactant) and triton X-100 (amphoteric surfactant) using an ultrasonic tip processor. Three concentrations of each surfactant (1mM, 10mM and 100mM) were tested, and all samples were sonicated until an adequate dispersion degree was obtained. Cement pastes with additions of carbon nanotubes of 0.15% by mass of cement were produced in two steps; first the dispersions of MWCNT were combined with the mixing water using an ultrasonic tip processor to guarantee homogeneity, and then cement was added and mixed until a homogeneous paste was obtained. Direct tensile strength, apparent density and open porosity of the pastes were measured after 7 days of curing. It was found that the MWCNT/surfactants dispersions decrease the mechanical properties of the cement based matrix due to an increased porosity caused by the presence of surfactants.

  12. Specially designed B4C/SnO2 nanocomposite for photocatalysis: traditional ceramic with unique properties

    Science.gov (United States)

    Singh, Paviter; Kaur, Gurpreet; Singh, Kulwinder; Singh, Bikramjeet; Kaur, Manpreet; Kaur, Manjot; Krishnan, Unni; Kumar, Manjeet; Bala, Rajni; Kumar, Akshay

    2018-02-01

    Boron carbide: A traditional ceramic material shows unique properties when explored in nano-range. Specially designed boron-based nanocomposite has been synthesized by reflux method. The addition of SnO2 in base matrix increases the defect states in boron carbide and shows unique catalytic properties. The calculated texture coefficient and Nelson-Riley factor show that the synthesized nanocomposite has large number of defect states. Also this composite is explored for the first time for catalysis degradation of industrial used dyes. The degradation analysis of industrial pollutants such as Novacron red Huntsman (NRH) and methylene blue (MB) dye reveals that the composite is an efficient catalyst. Degradation study shows that 1 g/L catalyst concentration of B4C/SnO2 degrades NRH and MB dye up to approximately 97.38 and 79.41%, respectively, in 20 min under sunlight irradiation. This water-insoluble catalyst can be recovered and reused.

  13. Unique antitumor property of the Mg-Ca-Sr alloys with addition of Zn

    Science.gov (United States)

    Wu, Yuanhao; He, Guanping; Zhang, Yu; Liu, Yang; Li, Mei; Wang, Xiaolan; Li, Nan; Li, Kang; Zheng, Guan; Zheng, Yufeng; Yin, Qingshui

    2016-02-01

    In clinical practice, tumor recurrence and metastasis after orthopedic prosthesis implantation is an intensely troublesome matter. Therefore, to develop implant materials with antitumor property is extremely necessary and meaningful. Magnesium (Mg) alloys possess superb biocompatibility, mechanical property and biodegradability in orthopedic applications. However, whether they possess antitumor property had seldom been reported. In recent years, it showed that zinc (Zn) not only promote the osteogenic activity but also exhibit good antitumor property. In our present study, Zn was selected as an alloying element for the Mg-1Ca-0.5Sr alloy to develop a multifunctional material with antitumor property. We investigated the influence of the Mg-1Ca-0.5Sr-xZn (x = 0, 2, 4, 6 wt%) alloys extracts on the proliferation rate, cell apoptosis, migration and invasion of the U2OS cell line. Our results show that Zn containing Mg alloys extracts inhibit the cell proliferation by alteration the cell cycle and inducing cell apoptosis via the activation of the mitochondria pathway. The cell migration and invasion property were also suppressed by the activation of MAPK (mitogen-activated protein kinase) pathway. Our work suggests that the Mg-1Ca-0.5Sr-6Zn alloy is expected to be a promising orthopedic implant in osteosarcoma limb-salvage surgery for avoiding tumor recurrence and metastasis.

  14. Synthesis and properties of aqueous polyurethane dispersions: Influence of molecular weight of polyethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Mumtaz, Fatima; Zuber, Mohammad; Zia, Khalid Mahmood [Government College University, Faisalabad (Pakistan); Jamil, Tahir [University of the Punjab, Lahore (Pakistan); Hussain, Rizwan [National Engineering and Scientific Commission (NESCOM), Islamabad (Pakistan)

    2013-12-15

    Aqueous polyurethane dispersions (PUDs) have recently emerged as important alternatives to their solvent-based counterparts for various applications due to increasing health and environmental awareness. A series of aqueous polyurethane dispersions containing carboxylate anion as hydrophilic pendant groups were synthesized through step growth polymerization reaction using hexamethylene diisocyanate (HDI), 1,4-butanediol (1,4-BDO), dimethylol propionic acid (DMPA) and polyethylene glycol (PEG) of different molecular weight. Effect of PEG molecular weight was investigated on molecular structure, contact angle measurement, and physical and adhesive properties of PU emulsions. Fourier transform infrared spectroscopy (FT-IR) was used to check the completion of polymerization reaction. Contact angle measurement indicated that the hydrophilicity of polymer increases by increasing molecular weight of PEG with a corresponding decrease in contact angle. Results of T-peel test showed a decrease in peel strength by increasing molecular weight of PEG. Moreover, solid contents%, drying time and storage stability suggested fast drying properties and greater stability of aqueous PU dispersions.

  15. Increased electrochemical properties of ruthenium oxide and graphene/ruthenium oxide hybrid dispersed by polyvinylpyrrolidone

    International Nuclear Information System (INIS)

    Chen, Yao; Zhang, Xiong; Zhang, Dacheng; Ma, Yanwei

    2012-01-01

    Highlights: ► A good dispersion of RuO 2 and graphene/RuO 2 is obtained by polyvinylpyrrolidone. ► PVP as a dispersant also can prevent the formation of metal Ru in graphene/RuO 2 . ► The max capacitances of the hybrid and RuO 2 reach 435 and 597 F g −1 at 0.2 A g −1 . ► The hybrid shows the best rate capability of 39% at 50 A g −1 . - Abstract: Ruthenium oxide has been prepared by a sol–gel method. Polyvinylpyrrolidone (PVP) as an excellent polymeric dispersant is adopted to prevent aggregation of ruthenium oxide. In order to enhance the rate capability of ruthenium oxide, graphene with residual oxygen functional groups as a 2D support has been merged into ruthenium oxide. These oxygen functional groups not only favor to form stable few layers of graphene colloids, but also offer the sites to anchor ruthenium oxide nanoparticles. X-ray diffraction infers that PVP can also hinder the partial formation of Ru by blocking the direct contact between the Ru 3+ and the graphene in the sol–gel synthesis of the hybrids. The ruthenium oxide and the graphene/ruthenium oxide hybrids dispersed by PVP have superior electrochemical properties due to good dispersing and protecting ability of PVP. Especially, the hybrids using PVP exhibit the best rate capability, indicating that the composites possess an advanced structure of combining sheets and particles in nano-scale.

  16. Synthesis of Novel Reactive Disperse Silicon-Containing Dyes and Their Coloring Properties on Silicone Rubbers

    Directory of Open Access Journals (Sweden)

    Ning Yu

    2018-01-01

    Full Text Available Novel red and purple reactive disperse silicon-containing dyes were designed and synthesized using p-nitroaniline and 6-bromo-2,4-dinitro-aniline as diazonium components, the first condensation product of cyanuric chloride and 3-(N,N-diethylamino-aniline as coupling component, and 3-aminopropylmethoxydimethylsilane, 3-aminopropylmethyldimethoxysilane, and 3-aminopropyltrimethoxysilane as silicone reactive agents. These dyes were characterized by UV-Vis, 1H-NMR, FT-IR, and MS. The obtained reactive disperse silicon-containing dyes were used to color silicone rubbers and the color fastness of the dyes were evaluated. The dry/wet rubbing and washing fastnesses of these dyes all reached 4–5 grade and the sublimation fastness was also above 4 grade, indicating outstanding performance in terms of color fastness. Such colored silicone rubbers showed bright and rich colors without affecting its static mechanical properties.

  17. Polarization and switching properties of holographic polymer-dispersed liquid-crystal gratings. I. Theoretical model

    Science.gov (United States)

    Sutherland, Richard L.

    2002-12-01

    Polarization properties and electro-optical switching behavior of holographic polymer-dispersed liquid-crystal (HPDLC) reflection and transmission gratings are studied. A theoretical model is developed that combines anisotropic coupled-wave theory with an elongated liquid-crystal-droplet switching model and includes the effects of a statistical orientational distribution of droplet-symmetry axes. Angle- and polarization-dependent switching behaviors of HPDLC gratings are elucidated, and the effects on dynamic range are described. A new type of electro-optical switching not seen in ordinary polymer-dispersed liquid crystals, to the best of the author's knowledge, is presented and given a physical interpretation. The model provides valuable insight to the physics of these gratings and can be applied to the design of HPDLC holographic optical elements.

  18. Effect of Acid Oxidation on the Dispersion Property of Multiwalled Carbon Nanotubes

    Science.gov (United States)

    Goh, P. S.; Ismail, A. F.; Aziz, M.

    2009-06-01

    A means of dispersion of multiwalled carbon nanotube (MWCNT) via mixed acid (HNO3 and H2SO4) oxidation with different treatment durations was investigated through the solubility study of the treated carbon nanotubes in some common solvents. Fourier transformed infrared (FTIR) characterization of the reaction products revealed that the surface of MWCNTs was successfully functionalized with surface acidic groups. The acid-base titration demonstrated that the amount of surface acidic groups increased in parallel with the refluxing duration. The acid modified MWCNTs were found to be well dispersed in polar solvents, such as ethanol and water due to the presence of the hydrophilic acid functional groups on the surface of raw MWCNTs. Such chemical modification of carbon nanotube properties will pave the way towards the realistic applications in the nanotechnology world.

  19. High heat load properties of TiC dispersed Mo alloys

    International Nuclear Information System (INIS)

    Tokunaga, Kazutoshi; Yoshida, Naoaki; Miura, Yasushi; Kurishita, Hiroaki; Kitsunai, Yuji; Kayano, Hideo.

    1996-01-01

    Electron beam high heat load experiment of new developed three kinds of TiC dispersed Mo alloys (Mo-0.1wt%TiC, Mo-0.5wt%TiC and Mo-1.0wt%TiC) was studied so as to evaluate it's high heat load at using as the surface materials of divertor. The obtained results indicated that cracks were not observed by embrittlement by recrystallization until about 2200degC of surface temperature and the gas emission properties were not different from sintered molibdenum. However, at near melting point, deep cracks on grain boundary and smaller gas emission than that of sintered Mo were observed. So that, we concluded that TiC dispersed Mo alloy was good surface materials used under the conditions of the stationary heat flux and less than the melting point, although not good one to be melted under nonstationary large heat flux. (S.Y.)

  20. Stabilizing ability of surfactant on physicochemical properties of drug nanoparticles generated from solid dispersions.

    Science.gov (United States)

    Thongnopkoon, Thanu; Puttipipatkhachorn, Satit

    2017-07-01

    This study was aimed to examine the nanoparticle formation from redispersion of binary and ternary solid dispersions. Binary systems are composed of various ratios of glibenclamide (GBM) and polyvinylpyrrolidone K30 (PVP-K30), whereas a constant amount at 2.5%w/w of a surfactant, sodium lauryl sulfate (SLS) or Gelucire44/14 (GLC), was added to create ternary systems. GBM nanoparticles were collected after the systems were dispersed in water for 15 min. The obtained nanoparticles were characterized for size distribution, crystallinity, thermal behavior, molecular structure, and dissolution properties. The results indicated that GBM nanoparticles could be formed when the drug content of the systems was lower than 30%w/w in binary systems and ternary systems containing SLS. The particle size ranged from 200 to 500 nm in diameter with narrow size distribution. The particle size was increased with increasing drug content in the systems. The obtained nanoparticles were spherical and showed the amorphous state. Furthermore, because of being amorphous form and reduced particle size, the dissolution of the generated nanoparticles was markedly improved compared with the GBM powder. In contrast, all the ternary solid dispersions prepared with GLC anomalously provided the crystalline particles with the size ranging over 5 µm and irregular shape. Interestingly, this was irrelevant to the drug content in the systems. These results indicated the ability of GLC to destabilize the polymer network surrounding the particles during particle precipitation. Therefore, this study suggested that drug content, quantity, and type of surfactant incorporated in solid dispersions drastically affected the physicochemical properties of the precipitated particles.

  1. Metallic nanoparticles: microbial synthesis and unique properties for biotechnological applications, bioavailability and biotransformation

    NARCIS (Netherlands)

    Pereira, L.; Mehboob, F.; Stams, A.J.M.; Mota, M.M.; Rijnaarts, H.H.M.; Alves, M.M.

    2015-01-01

    The impact of nanotechnology in all areas of science and technology is evident. The expanding availability of a variety of nanostructures with properties in the nanometer size range has sparked widespread interest in their use in biotechnological systems, including the field of environmental

  2. Solec Spa – worldwide unique properties of Polish health resort in the service of rural medicine

    Directory of Open Access Journals (Sweden)

    Marek L Grabowski

    2018-03-01

    Full Text Available Solec Spa is health resort in south-eastern Poland. Its unique balneorehabilitation significance worldwide is determined by chloride-iodine-sodium water with a high content of hydrogen sulphide. This water, classified as highly mineralized sodium-chloride (seltzer sulphide, bromide, iodide, boron water, contains naturally approximately 0.9 g/l divalent sulphur compounds, which is the highest concentration noted among the mineral waters of the world. The effectiveness of the Solec waters is proven in: inflammatory and autoimmunological locomotor system diseases, degenerative joint disorders (osteoarthritis, post-traumatic and post-operative orthopedic diseases, skin diseases and allergic disorders. One of the main indications for balneotherapy in Solec Spa and Busko Spa is chronic brucellosis.

  3. Curcumolide, a unique sesquiterpenoid with anti-inflammatory properties from Curcuma wenyujin.

    Science.gov (United States)

    Dong, Jianyong; Shao, Weiwei; Yan, Pengcheng; Cai, Xiaoqing; Fang, Lianglian; Zhao, Xiaowei; Lin, Weiwei; Cai, Yuan

    2015-01-15

    Curcumolide, a novel sesquiterpenoid with a unique 5/6/5 tricyclic skeleton, was isolated from Curcuma wenyujin. The structure and absolute configuration were elucidated by extensive NMR, ECD data analysis, and a single-crystal X-ray study. This molecule exhibited significant anti-inflammatory effects in LPS-induced RAW 264.7 macrophages. It suppressed LPS-induced NF-κB activation, including the nuclear translocation and DNA binding activity of NF-κB, and decreased tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), nitric oxide (NO) and reactive oxygen species (ROS) production. Therefore, Curcumolide may have therapeutic potential for treating inflammatory diseases by inhibiting NF-κB activation and pro-inflammatory mediator production. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Some properties of a unique cadmium-binding moiety in the soluble fraction of rat testes

    International Nuclear Information System (INIS)

    Chen, R.W.; Ganther, H.E.

    1975-01-01

    A 30000 molecular weight testicular Cd-binding peak (30000 MW CdBP) previously implicated in Cd-induced testicular injury was unstable during storage with respect to apparent molecular weight determined by Sephadex G-75 chromatography. Storage of testicular cytosol labeled with 109 Cd in vivo or in vitro for several days at 4degC under nitrogen resulted in disappearance of the 30000 MW Cd-BP and increased 109 Cd uptake in other protein fractions. Rechromatography of the previously isolated 30000 MW Cd-BP after storage gave rise to a 109 Cd peak eluting in the higher molecular weight region. The latter effect was prevented by 1 mM dithiothreitol, suggesting that sulfhydryl groups were involved in the apparent aggregation. The 30000 MW Cd-BP found in testes of rats was not present in testes of roosters, nor in liver and kidney of either species, providing further evidence of a correlation between the occurrence of 30000 MW Cd-BP protein in the tissue and susceptibility to Cd-injury. The inability of parenterally administered HgCl 2 to induce testicular injury compared to the same dose of CdCl 2 (0.011mmol/kg) is apparently related to the poor uptake of Hg in the testes (one-eighteenth that of Cd) rather than to an inability of Hg to bind to the 30000 MW Cd-BP. Our studies indicate that binding of Cd to this unique 30000 MW testicular component, as yet unidentified, is a possible basis for the unique sensitivity of the testis to Cd injury. (author)

  5. Fatigue properties of MA 6000E, a gamma-prime strengthened ODS alloy. [Oxide Dispersion Strengthened Ni-base alloy for gas turbine blade applications

    Science.gov (United States)

    Kim, Y. G.; Merrick, H. F.

    1980-01-01

    MA 6000E is a corrosion resistant, gamma-prime strengthened ODS alloy under development for advanced turbine blade applications. The high temperature, 1093 C, rupture strength is superior to conventional nickel-base alloys. This paper addresses the fatigue behavior of the alloy. Excellent properties are exhibited in low and high cycle fatigue and also thermal fatigue. This is attributed to a unique combination of microstructural features, i.e., a fine distribution of dispersed oxides and other nonmetallics, and the highly elongated grain structure which advantageously modify the deformation characteristics and crack initiation and propagation modes from that characteristic of conventional gamma-prime hardened superalloys.

  6. Electromagnetic wave absorption properties of composites with micro-sized magnetic particles dispersed in amorphous carbon

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bin Peng [Research Center of Carbon Fiber, Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials of Ministry of Education, Shandong University, Jinan 250061 (China); Tianjin Binhai New Area Finance Bureau, Tianjin 300450 (China); Wang, Cheng Guo, E-mail: sduwangchg@gmail.com [Research Center of Carbon Fiber, Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials of Ministry of Education, Shandong University, Jinan 250061 (China); Wang, Wen [Norinco Group China North Material Science and Engineering Technology Group Corporation, Jinan 250031 (China); Yu, Mei Jie; Gao, Rui; Chen, Yang; Xiang Wang, Yan [Research Center of Carbon Fiber, Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials of Ministry of Education, Shandong University, Jinan 250061 (China)

    2014-09-01

    Composites with micro-sized magnetic particles dispersed in amorphous carbon were fabricated conveniently and economically by carbonizing polyacrylonitrile (PAN) fibers mixed with micro-sized iron particles under different temperatures. The composites were characterized by X-ray diffraction (XRD) and scanning electric microscope (SEM). The electromagnetic (EM) properties were measured by a vector network analyzer in the frequency range of 2–18 GHz based on which analog computations of EM wave absorption properties were carried out. The influences of temperature on phase composition and EM wave absorption properties were also investigated, indicating that the composites had good electromagnetic absorption properties with both electrical loss and magnetic loss. Effective reflection loss (RL<−10 dB) was observed in a large frequency range of 7.5–18 GHz with the absorber thickness of 2.0–3.0 mm for the paraffin samples with composite powders heated up to 750 °C and the minimum absorption peak around −40 dB appeared at approximately 10 GHz with matching thickness of 2.0 mm for the paraffin sample with composite powders heated up to 800 °C. - Highlights: • High-performance electromagnetic wave absorption materials were fabricated conveniently and economically. • The materials are composites with micro-sized magnetic particles dispersed in porous amorphous carbon. • The influences of temperature on phase composition and electromagnetic wave absorption properties were investigated. • The composites heated up to 750 °C and 800 °C had good electromagnetic wave absorption property.

  7. Microstructure and mechanical properties of an oxide dispersion strengthened ferritic steel by a new fabrication route

    International Nuclear Information System (INIS)

    Guo Lina; Jia Chengchang; Hu Benfu; Li Huiying

    2010-01-01

    A reduced activation oxide dispersion strengthened (ODS) ferritic steel with nominal composition of Fe-12Cr-2.5W-0.25Ti-0.2V-0.4Y 2 O 3 (designated 12Cr-ODS) was produced by using EDTA-citrate complex method to synthesize and add Y 2 O 3 particles to an argon atomized steel powder, followed by hot isostatic pressing at 1160 deg. C for 3 h under the pressure of 130 MPa, forging at 1150 deg. C, and heat treatment at 1050 deg. C for 2 h. The microstructure, tensile, and Charpy impact properties of the 12Cr-ODS steel were investigated. Transmission electron microscopy studies indicate that the 12Cr-ODS steel exhibits the characteristic ferritic structure containing few dislocations. Tensile characterization has shown that the 12Cr-ODS steel has superior tensile strength accompanied by good elongation at room temperature and 550 deg. C. The material exhibits very attractive Charpy impact properties with upper shelf energy of 22 J and a ductile-to-brittle transition temperature (DBTT) of about -15 deg. C. The formation of small, equiaxed grains and fine dispersion of oxide particles are the main reasons for the good compromise between tensile strength and impact properties.

  8. Enhanced electromagnetic properties of nickel nanoparticiles dispersed carbon fiber via electron beam irradiation

    International Nuclear Information System (INIS)

    Lee, Yeong Ju; Kim, Hyun Bin; Lee, Seung Jun; Kang, Phil Hyun

    2015-01-01

    Carbon fiber has received much attention owing to its properties, including a large surface-to-volume ratio, chemical and thermal stability, high thermal and electrical conductivity, and high mechanical strengths. In particular, magnetic nanopowder dispersed carbon fiber has been attractive in technological applications such as the electrochemical capacitor and electromagnetic wave shielding. In this study, the nickel-oxide-nanoparticle dispersed polyacrylonitrile (PAN) fibers were prepared through an electrospinning method. Electron beam irradiation was carried out with a 2.5 MeV beam energy to stabilize the materials. The samples were then heat treated for stabilization and carbonization. The nanofiber surface was analyzed using a field emission scanning electron microscope (FE-SEM). The crystal structures of the carbon matrix and nickel nanopowders were analysed using X-ray diffraction (XRD). In addition, the magnetic and electrical properties were analyzed using a vibrating sample magnetometer (VSM) and 4 point probe. As the irradiation dose increases, the density of the carbon fiber was increased. In addition, the electrical properties of the carbon fiber improved through electron beam irradiation. This is because the amorphous region of the carbon fiber decreases. This electron beam effect of PAN fibers containing nickel nanoparticles confirmed their potential as a high performance carbon material for various applications

  9. Microstructure and mechanical properties of an oxide dispersion strengthened ferritic steel by a new fabrication route

    Energy Technology Data Exchange (ETDEWEB)

    Guo Lina, E-mail: guoln702@yahoo.com.cn [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Jia Chengchang; Hu Benfu; Li Huiying [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2010-07-25

    A reduced activation oxide dispersion strengthened (ODS) ferritic steel with nominal composition of Fe-12Cr-2.5W-0.25Ti-0.2V-0.4Y{sub 2}O{sub 3} (designated 12Cr-ODS) was produced by using EDTA-citrate complex method to synthesize and add Y{sub 2}O{sub 3} particles to an argon atomized steel powder, followed by hot isostatic pressing at 1160 deg. C for 3 h under the pressure of 130 MPa, forging at 1150 deg. C, and heat treatment at 1050 deg. C for 2 h. The microstructure, tensile, and Charpy impact properties of the 12Cr-ODS steel were investigated. Transmission electron microscopy studies indicate that the 12Cr-ODS steel exhibits the characteristic ferritic structure containing few dislocations. Tensile characterization has shown that the 12Cr-ODS steel has superior tensile strength accompanied by good elongation at room temperature and 550 deg. C. The material exhibits very attractive Charpy impact properties with upper shelf energy of 22 J and a ductile-to-brittle transition temperature (DBTT) of about -15 deg. C. The formation of small, equiaxed grains and fine dispersion of oxide particles are the main reasons for the good compromise between tensile strength and impact properties.

  10. Enhanced electromagnetic properties of nickel nanoparticiles dispersed carbon fiber via electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yeong Ju; Kim, Hyun Bin; Lee, Seung Jun; Kang, Phil Hyun [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2015-02-15

    Carbon fiber has received much attention owing to its properties, including a large surface-to-volume ratio, chemical and thermal stability, high thermal and electrical conductivity, and high mechanical strengths. In particular, magnetic nanopowder dispersed carbon fiber has been attractive in technological applications such as the electrochemical capacitor and electromagnetic wave shielding. In this study, the nickel-oxide-nanoparticle dispersed polyacrylonitrile (PAN) fibers were prepared through an electrospinning method. Electron beam irradiation was carried out with a 2.5 MeV beam energy to stabilize the materials. The samples were then heat treated for stabilization and carbonization. The nanofiber surface was analyzed using a field emission scanning electron microscope (FE-SEM). The crystal structures of the carbon matrix and nickel nanopowders were analysed using X-ray diffraction (XRD). In addition, the magnetic and electrical properties were analyzed using a vibrating sample magnetometer (VSM) and 4 point probe. As the irradiation dose increases, the density of the carbon fiber was increased. In addition, the electrical properties of the carbon fiber improved through electron beam irradiation. This is because the amorphous region of the carbon fiber decreases. This electron beam effect of PAN fibers containing nickel nanoparticles confirmed their potential as a high performance carbon material for various applications.

  11. On the properties of two pulses propagating simultaneously in different dispersion regimes in a nonlinear planar waveguide

    International Nuclear Information System (INIS)

    Pietrzyk, M.E.

    1999-02-01

    Properties of two pulses propagating simultaneously in different dispersion regimes, anomalous and normal, in a Kerr-type planar waveguide are studied. It is found that the presence of the pulse propagating in normal dispersion regime can cause termination of catastrophic self-focusing of the pulse propagating in anomalous regime. It is also shown that the coupling between pulses can lead to spatio-temporal splitting of the pulse propagating in anomalous dispersion regime, but it does not lead to catastrophic self-focusing of the pulse propagating in normal dispersion regime. For the limiting case when the dispersive term of the pulse propagating in normal dispersion regime can be neglected an indication (based on the variational estimation) to a possibility of a stable self-trapped propagation of both pulses is obtained. This stabilization is similar to the one which was found earlier in media with saturation-type nonlinearity. (author)

  12. Preparation of In2S3 nanopraricle by ultrasonic dispersion and its tribology property.

    Science.gov (United States)

    Li, Zhiwei; Tao, Xiaojun; Wu, Zhishen; Zhang, Pingyu; Zhang, Zhijun

    2009-02-01

    In this paper, we describe a facile and rapid method for preparing In2S3 nanoparticles via ultrasound dispersion. This method allows us to prepare In2S3 nanoparticles from bulk indium and sulfur with ease and without using expensive agents and in a short time. The possible growing mechanism of the In2S3 nanoparticles was presented. In addition, we provide detailed characterizations including TEM, XRD, TG-DTA, and XPS to study the shape, composition and structure of In2S3 nanoparticles. We also studied the tribology property of In2S3 nanoparticles made using this novel recipe.

  13. The creep properties of a low alloy ferritic steel containing an intermetallic precipitate dispersion

    International Nuclear Information System (INIS)

    Batte, A.D.; Murphy, M.C.; Edmonds, D.V.

    1976-01-01

    A good combination of creep rupture ductility and strength together with excellent long term thermal stability, has been obtained from a dispersion of intermetallic Laves phase precipitate in a non-transforming ferritic low alloy steel. The steel is without many of the problems currently associated with the heat affected zone microstructures of low alloy transformable ferritic steels, and can be used as a weld metal. Following suitable development to optimize the composition and heat treatment, such alloys may provide a useful range of weldable creep resistant steels for steam turbine and other high temperature applications. They would offer the unique possibility of easily achievable microstructural uniformity, giving good long term strength and ductility across the entire welded joint

  14. Derivation of equations for scalar and fermion fields using properties of dispersion-codispersion operators

    International Nuclear Information System (INIS)

    Raoelina Andriambololona; Ranaivoson, R.T.R; Hanitriarivo, R.; Harison, V.

    2014-01-01

    We establish equations for scalar and fermion fields using results obtained from a study on a phase space representation of quantum theory that we have performed in a previous work. Our approaches are similar to the historical ones to obtain Klein-Gordon and Dirac equations but the main difference is that ours are based on the use of properties of operators called dispersion-codispersion operators. We begin with a brief recall about the dispersion-codispersion operators. Then, introducing a mass operator with its canonical conjugate coordinate and applying rules of quantization, based on the use of dispersion - codispersion operators , we deduce a second order differential operator relation from the relativistic expression relying energy, momentum and mass. Using Dirac matrices, we derive from this second order differential operator relation a first order one. The application of the second order differential operator relation on a scalar function gives the equation for the scalar field and the use of the first order differential operator relation leads to the equation for fermion field.

  15. Preparations and thermal properties of micro- and nano-BN dispersed HDPE composites

    International Nuclear Information System (INIS)

    Jung, Jinwoo; Kim, Jaewoo; Uhm, Young Rang; Jeon, Jae-Kyun; Lee, Sol; Lee, Hi Min; Rhee, Chang Kyu

    2010-01-01

    The thermal properties of micro-sized boron nitride (BN) and nano-sized BN dispersed high density polyethylene (HDPE) composites were investigated by means of differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). Nano-BN powder was prepared by using a ball mill process before it was mixed in HDPE. To enhance the dispersivity of nano-BN in the polymer matrix, the surfaces of the nano-particles were treated with low density polyethylene (LDPE) which was dissolved in the cyclohexane solvent. The average particle sizes of micro-BN powder and LDPE coated nano-BN powder were ∼10 μm and ∼100 nm respectively. Dispersion and distribution of 5 wt% and 20 wt% of micro-BN and nano-BN respectively mixed in HDPE were observed by using the scanning electron microscope (SEM). According to the thermal analyses of pure HDPE, micro-BN/HDPE, and nano-BN/HDPE, 20 wt% nano-BN/HDPE composite shows the lowest enthalpy of fusion (ΔH m ) and better thermal conductive characteristics compared to the others.

  16. The Effects of Ammonium Polyacrylate and Diammonium Citrate as Base and Acid Dispersion Agents on Yttria-Stabilized Zirconia (3Y-TZP Dispersion Properties

    Directory of Open Access Journals (Sweden)

    Pestaria Sinaga

    2018-01-01

    Full Text Available Stable slurries in dispersions of 3Y-TZP in aqueous suspension with the addition of different concentrations of dispersants such as ammonium polyacrylate (APA and diammonium citrate (DAC were investigated. The dispersion properties were investigated by measuring the particle size, zeta potential, sedimentation, and viscosity as a function of the wt.% of the dispersant. Both dispersant agents were attached to the 3Y-TZP surface by the carboxylic group, as shown by the FTIR results. The addition of dispersants was found to produce more dispersed and stabilized aqueous suspension. As shown the viscosity result, that there is no being viscosity peak has been occurring and viscosity going decrease as the shear rates increasing which mean that the suspension has shear thinning behavior and there is no agglomeration as the shear rate is increased. It was determined that 3.5 wt.% of DAC and APA produced the best and most stable slurry; when 3.5 wt.% of DAC and APA was added, the zeta potential showed the largest value in the monodisperse condition. The low pH value of DAC has obtained the higher zeta potential value than APA, which was assumed due to low pH of DAC suspension. At low pH, the adsorption of the adsorbate will occur in a flat adsorbed, while at higher pH the polyelectrolyte will dangle into solution, thus reducing electrostatic repulsion as it is found in the case of APA addition. In this condition, the particle size was decreased to the lower value and the slurry’s stability was obtained with the lowest sedimentation height after the sedimentation test for 30 days. The sample was milled in an attrition mill at 1,000 rpm for four hours.

  17. The unique properties of agricultural aerosols measured at a cattle feeding operation

    Science.gov (United States)

    Hiranuma, N.; Brooks, S. D.; Gramann, J.; Auvermann, B. W.

    2011-05-01

    Housing roughly 10 million head of cattle in the United States alone, open air cattle feedlots represent a significant but poorly constrained source of atmospheric particles. Here we present a comprehensive characterization of physical and chemical properties of particles emitted from a large representative cattle feedlot in the Southwest United States. In the summer of 2008, measurements and samplings were conducted at the nominally upwind and downwind edges of the facility. A series of far-field measurements and samplings was also conducted 3.5 km north of the facility. Two instruments, a GRIMM Sequential Mobility Particle Sizer (SMPS) and a GRIMM Portable Aerosol Spectrometer (PAS), were used to measure particle size distributions over the range of 0.01 to 25 μm diameter. Raman microspectroscopy (RM) was used to determine the chemical composition of particles on a single particle basis. Volume size distributions of fugitive dust were dominated by coarse mode particles. Twenty-four hour averaged concentrations of PM10 (particulate matter with a diameter of 10 μm or less) were as high as 1200 μg m-3 during the campaign. The primary constituents of the particulate matter were carbonaceous materials, such as humic acid, water soluble organics, and less soluble fatty acids, including stearic acid and tristearin. A significant percentage of the organic particles, up to 28 %, were composed of internally mixed with salts. Basic characteristics such as size distribution and composition of agricultural aerosols were found to be different than the properties of those found in urban and semi-urban aerosols. Failing to account for such differences will lead to serious errors in estimates of aerosol effects on climate, visibility, and public health.

  18. Immunodominant role of CCHA subunit of Concholepas hemocyanin is associated with unique biochemical properties.

    Science.gov (United States)

    Becker, María Inés; Fuentes, Alejandra; Del Campo, Miguel; Manubens, Augusto; Nova, Esteban; Oliva, Harold; Faunes, Fernando; Valenzuela, María Antonieta; Campos-Vallette, Marcelo; Aliaga, Alvaro; Ferreira, Jorge; De Ioannes, Alfredo E; De Ioannes, Pablo; Moltedo, Bruno

    2009-03-01

    Hemocyanin, the oxygen transporter metallo-glycoprotein from mollusks, shows strong relationship between its notable structural features and intrinsic immunomodulatory effects. Here we investigated the individual contribution of CCHA and CCHB subunits from Concholepas hemocyanin (CCH) to in vivo humoral immune response and their pre-clinical evaluation as immunotherapeutic agent in a mice bladder cancer model, in relation to their biochemical properties. To this end, subunits were purified and well characterized. Homogeneous subunits were obtained by anionic exchange chromatography, and its purity assessed by electrophoretic and immunochemical methods. While each CCH subunit contains eight functional units showing partial cross reaction, the vibrational spectral analysis showed several spectral differences, suggesting structural differences between them. In addition, we demonstrated differences in the carbohydrate content: CCHA had a 3.6% w/w sugar with both N- and O-linked moieties. In turn, CCHB had a 2.5% w/w sugar with N-linked, while O-linked moieties were nearly absent. Considering these differences, it was not possible to predict a priori whether the immunogenic and immunotherapeutic properties of subunits might be similar. Surprisingly, both subunits by itself induced a humoral response, and showed an antitumor effect in the bladder carcinoma cell line MBT-2. However, when immunologic parameters were analyzed, CCHA showed better efficiency than CCHB. No allergic reactions or any toxic effects were observed in mice treated with CCHA, sustaining its potential therapeutic use. Our study supports that CCHA subunit accounts for the most important features involved in the immunogenicity of CCH, such as better hydrophilicity and higher content of carbohydrates.

  19. Magnetic properties of Ni nanoparticles dispersed in silica prepared by high-energy ball milling

    Science.gov (United States)

    González, E. M.; Montero, M. I.; Cebollada, F.; de Julián, C.; Vicent, J. L.; González, J. M.

    1998-04-01

    We analyze the magnetic properties of mechanically ground nanosized Ni particles dispersed in a SiO2 matrix. Our magnetic characterization of the as-milled samples show the occurrence of two blocking processes and that of non-monotonic milling time evolutions of the magnetic-order temperature, the high-field magnetization and the saturation coercivity. The measured coercivities exhibit giant values and a uniaxial-type temperature dependence. Thermal treatment carried out in the as-prepared samples result in a remarkable coercivity reduction and in an increase of the high-field magnetization. We conclude, on the basis of the consideration of a core (pure Ni) and shell (Ni-Si inhomogeneous alloy) particle structure, that the magnetoelastic anisotropy plays the dominant role in determining the magnetic properties of our particles.

  20. The Logistics of Oil Spill Dispersant Application. Volume I. Logistics-Related Properties of Oil Spill Dispersants.

    Science.gov (United States)

    1982-11-01

    time of application. Such designs were probably influenced by the ready availabilit " 51 of fire-fighting hoses on ships and tugs; the water stream not...8217 I I1 ---- i . . .. . IIII . . . I I PREFACE The use of chemicals for the dispersal of oil spilled on water has been the subject of discussion (and of...20 Oil Type, Weathering and Emulsification.. 20 Slick Thickness .......................... 28 Water Temperature

  1. Carbon Nanofibers-Poly-3-hydroxyalkanoates Nanocomposite: Ultrasound-Assisted Dispersion and Thermostructural Properties

    Directory of Open Access Journals (Sweden)

    A. M. Gumel

    2014-01-01

    Full Text Available The conductivity and high surface-to-volume ratio of carbon nanofibers (CNFs composited with the medium-chain-length poly-3-hydroxyalkanoate (mcl-PHA have attracted much attention as smart biomaterial. However, poor CNF dispersion leads to tactoid agglomerated composite with poor crystallite morphology resulting in inferior thermomechanical properties. We employed acoustic sonication to enhance the construction of exfoliated PHA/CNFs nanocomposites. The effects of CNF loading and the insonation variables (power intensity, frequency, and time on the stability and microscopic morphology of the nanocomposites were studied. Sonication improved the dispersion of CNFs into the polymer matrix, thereby improving the physical morphology, crystallinity, and thermomechanical properties of the nanocomposites. For example, compositing the polymer with 10% w/w CNF resulted in 66% increase in crystallite size, 46% increase in micromolecular elastic strain, and 17% increase in lattice strain. Nevertheless, polymer degradation was observed following the ultrasound exposure. The constructed bionanocomposite could potentially be applied for organic electroconductive materials, biosensors and stimuli-responsive drug delivery devices.

  2. Improved Mechanical and Tribological Properties of Metal-Matrix Composites Dispersion-Strengthened by Nanoparticles

    Directory of Open Access Journals (Sweden)

    Evgenii Levashov

    2009-12-01

    Full Text Available Co- and Fe-based alloys produced by powder technology are being widely used as a matrix for diamond-containing composites in cutting, drilling, grinding pplications, etc. The severe service conditions demand that the mechanical and tribological properties of these alloys be improved. Development of metal-matrix composites (MMCs and alloys reinforced with nanoparticles is a promising way to resolve this problem. In this work, we have investigated the effect of nano-sized WC, ZrO2, Al2O3, and Si3N4 additives on the properties of sintered dispersion-strengthened Co- and Fe-based MMCs. The results show an increase in the hardness (up to 10 HRB, bending strength (up to 50%, wear resistance (by a factor of 2–10 and a decrease in the friction coefficient (up to 4-fold of the dispersion-strengthened materials. The use of designed alloys as a binder of cutting diamond tools gave a 4-fold increment in the service life, without reduction in their cutting speed.

  3. Preparation and optical properties of gold-dispersed BaTiO3 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kineri, T; Mori, M [TDK Corp., Tokyo (Japan). R and D Center; Kadono, K; Sakaguchi, T; Miya, M; Wakabayashi, H [Osaka National Research Inst., Osaka (Japan); Tsuchiya, T [Science Univ. of Tokyo, Tokyo (Japan). Faculty of Industrial Science and Technology

    1993-12-01

    Recently, metal or semiconductor-doped glasses were widely studied because of their large resonant third-order nonlinearity. These glasses are utilized in an optical information field as all optical logic devices in the future. The gold-doped glass films or thin layers have a large third-order nonlinear susceptibility [chi] and are prepared by r.f. sputtering method, etc. The optical properties, particularly the refractive index or dielectric constant of the matrix, are very important for the optical nonlinearity of these materials. In this study, gold-dispersed BaTiO3 thin films and gold-dispersed SiO2 thin films are prepared using r.f. magnetron sputtering method, and the optical properties of the films are compared. The [chi] of the films are measured and the effect of the matrix of the films on [chi] is investigated. The headings in the paper are: Introduction, Experimental procedure, Results, Discussion, and Conclusion. 13 refs., 9 figs.

  4. Dispersion stability and thermophysical properties of environmentally friendly graphite oil–based nanofluids used in machining

    Directory of Open Access Journals (Sweden)

    Yu Su

    2016-01-01

    Full Text Available As environmentally friendly cutting fluids, vegetable-based oil and ester oil are being more and more widely used in metal cutting industry. However, their cooling and lubricating properties are required to be further improved in order to meet more cooling and lubricating challenges in high-efficiency machining. Nanofluids with enhanced heat carrying and lubricating capabilities seem to give a promising solution. In this article, graphite oil–based nanofluids with LB2000 vegetable-based oil and PriEco6000 unsaturated polyol ester as base fluids were prepared by ultrasonically assisted two-step method, and their dispersion stability and thermophysical properties such as viscosity and thermal conductivity were experimentally and theoretically investigated at different ultrasonication times. The results indicate that graphite-PriEco6000 nanofluid showed better dispersion stability, higher viscosity, and thermal conductivity than graphite-LB2000 nanofluid, which made it more suitable for application in high-efficiency machining as coolant and lubricant. The theoretical classical models showed good agreement with the thermal conductivity values of graphite oil–based nanofluids measured experimentally. However, the deviation between the experimental values of viscosity and the theoretical models was relatively big. New empirical correlations were proposed for predicting the viscosity of graphite oil–based nanofluids at various ultrasonication times.

  5. Antidepressant-like property of Jobelyn®, an African unique herbal formulation, in mice.

    Science.gov (United States)

    Umukoro, S; Eduviere, A T; Aladeokin, A C; Olugbemide, A S

    2014-03-01

    The purpose of this investigation was to evaluate whether Jobelyn® (JB) possesses anti-depressant-like property in the mouse forced swimming test (FST), tail suspension test (TST) and yohimbine-induced lethality test (YLT) in aggregated mice. Mice were given JB (10-100 mg/kg, p.o.) daily for 7 days and then subjected to FST, TST, YLT and open field test. The parameters assessed in both FST and TST were the time (s) spent in active movement (struggling time), first occurrence of immobility (s) and the duration of immobility (s). In the YLT, the mortality rate was recorded 24 h after yohimbine (35 mg/kg, i.p.) administration. In the open field test, the number of line crosses and total distance travelled (m) were measured for 10 min in the open field chamber. JB significantly (popen-field test. Jobelyn® has antidepressant-like activity, which may be related to the stimulation of serotonergic and noradrenergic pathways. The ability of Jobelyn® to delay the onset of immobility and to prolong the struggling time support its use as energizer in general body weakness or exhaustion. © Georg Thieme Verlag KG Stuttgart · New York.

  6. Unique Optical Properties of Methylammonium Lead Iodide Nanocrystals Below the Bulk Tetragonal-Orthorhombic Phase Transition.

    Science.gov (United States)

    Diroll, Benjamin T; Guo, Peijun; Schaller, Richard D

    2018-02-14

    Methylammonium (MA) and formamidinium (FA) lead halides are widely studied for their potential as low-cost, high-performance optoelectronic materials. Here, we present measurements of visible and IR absorption, steady state, and time-resolved photoluminescence from 300 K to cryogenic temperatures. Whereas FAPbI 3 nanocrystals (NCs) are found to behave in a very similar manner to reported bulk behavior, colloidal nanocrystals of MAPbI 3 show a departure from the low-temperature optical behavior of the bulk material. Using photoluminescence, visible, and infrared absorption measurements, we demonstrate that unlike single crystals and polycrystalline films NCs of MAPbI 3 do not undergo optical changes associated with the bulk tetragonal-to-orthorhombic phase transition, which occurs near 160 K. We find no evidence of frozen organic cation rotation to as low as 80 K or altered exciton binding energy to as low as 3 K in MAPbI 3 NCs. Similar results are obtained in MAPbI 3 NCs ranging from 20 to over 100 nm and in morphologies including cubes and plates. Colloidal MAPbI 3 NCs therefore offer a window into the properties of the solar-relevant, room-temperature phase of MAPbI 3 at temperatures inaccessible with single crystals or polycrystalline samples. Exploiting this phenomenon, these measurements reveal the existence of an optically passive photoexcited state close to the band edge and persistent slow Auger recombination at low temperature.

  7. Effect of carbon fiber dispersion on the mechanical properties of carbon fiber-reinforced cement-based composites

    International Nuclear Information System (INIS)

    Wang Chuang; Li Kezhi; Li Hejun; Jiao Gengsheng; Lu Jinhua; Hou Dangshe

    2008-01-01

    The preparation of carbon fiber-reinforced cement-based composites involved two-step dispersions of carbon fibers. Both steps affected greatly the mechanical properties of the composites. With the aid of ultrasonic wave, a new dispersant hydroxyethyl cellulose was used to help fiber dispersion in the first step. The fracture surface of the composites was observed by scanning electron microscopy. The distribution of major elements was analyzed by the energy dispersive spectroscopy and the composition was analyzed through X-ray diffraction. The flexural strength, tensile strength, modulus, and compression strength were measured. Results showed that the distribution of major elements varied with the variation of the fiber dispersion status. The compressive strength increased by 20%, the tensile strength was 2.4 times that of the material without carbon fibers, the modulus increased by 26.8%, whereas the flexure stress decreased by 12.9%

  8. Cellulose nanocrystal/polyolefin biocomposites prepared by solid-state shear pulverization: Superior dispersion leading to synergistic property enhancements

    Science.gov (United States)

    Krishnan A. Iyer; Gregory T. Schueneman; John M. Torkelson

    2015-01-01

    Cellulose nanocrystals (CNCs), a class of renewable bionanomaterials with excellent mechanical properties, have gained major interest as filler for polymers. However, challenges associated with effective CNC dispersion have hindered the production of composites with desired property enhancements. Here, composites of polypropylene (PP) and low density polyethylene (LDPE...

  9. A study of preparation techniques and properties of bulk nanocomposites based on aqueous albumin dispersion

    Science.gov (United States)

    Gerasimenko, A. Yu.; Dedkova, A. A.; Ichkitidze, L. P.; Podgaetskii, V. M.; Selishchev, S. V.

    2013-08-01

    Bulk nanocomposites prepared from an aqueous albumin dispersion with carbon nanotubes by removing the liquid component from the dispersion have been investigated. The composites were obtained by thermostating and exposure to LED and IR diode laser radiation. The nanocomposites obtained under laser irradiation retain their shape and properties for several years, in contrast to the composites fabricated in different ways (which decompose into small fragments immediately after preparation). The low density of the composites under study (˜1200 kg/m3), which is close to the density of water, is due to their high porosity. The hardness of stable nanocomposites (˜300 MPa) was found to be at the same level as the hardness of polymethylmethacrylate, aluminum, and iron and close to the hardness of human bone tissue. The cluster quasiordering of the inner structure of nanocomposites revealed by atomic force microscopy indicates the possibility of forming a bulk nanotube framework in them, which can be caused by the effect of the electric field of laser radiation and ensure their stability and hardness. The presence of a framework in nanocomposites provides conditions for self-assembly of biological tissues and makes it possible to apply laser-prepared nanocomposites as a component of surgical implants.

  10. From nanoparticles to fibres: effect of dispersion composition on fibre properties

    Science.gov (United States)

    Schirmer, Katharina S. U.; Esrafilzadeh, Dorna; Thompson, Brianna C.; Quigley, Anita F.; Kapsa, Robert M. I.; Wallace, Gordon G.

    2015-06-01

    A polyvinyl alcohol (PVA)-stabilized polypyrrole nanodispersion has been optimised for conductivity and processability by decreasing the quantity of PVA before and after synthesis. A reduction of PVA before synthesis leads to the formation of particles with a slight increase in dry particle diameter (51 ± 6 to 63 ± 3 nm), and conversely a reduced hydrodynamic diameter. Conductivity of the dried nanoparticle films was not measureable after a reduction of PVA prior to synthesis. Using filtration of particles after synthesis, PVA content was sufficiently reduced to achieve dried thin film conductivity of 2 S cm-1, while the electroactivity of the dispersed particles remained unchanged. The as-synthesized and PVA-reduced polypyrrole particles were successfully spun into all-nanoparticle fibres using a wet-extrusion approach without the addition of any polymer or gel matrix. Using nanoparticles as a starting material is a novel approach, which allowed the production of macro-scale fibres that consisted entirely of polypyrrole nanoparticles. Fibres made from PVA-reduced polypyrrole showed higher electroactivity compared to fibres composed of the dispersion high in PVA. The mechanical properties of the fibres were also improved by reducing the amount of PVA present, resulting in a stronger, more ductile and less brittle fibre, which could find potential application in various fields.

  11. Processing and properties of magnesium containing a dense uniform dispersion of nanoparticles.

    Science.gov (United States)

    Chen, Lian-Yi; Xu, Jia-Quan; Choi, Hongseok; Pozuelo, Marta; Ma, Xiaolong; Bhowmick, Sanjit; Yang, Jenn-Ming; Mathaudhu, Suveen; Li, Xiao-Chun

    2015-12-24

    Magnesium is a light metal, with a density two-thirds that of aluminium, is abundant on Earth and is biocompatible; it thus has the potential to improve energy efficiency and system performance in aerospace, automobile, defence, mobile electronics and biomedical applications. However, conventional synthesis and processing methods (alloying and thermomechanical processing) have reached certain limits in further improving the properties of magnesium and other metals. Ceramic particles have been introduced into metal matrices to improve the strength of the metals, but unfortunately, ceramic microparticles severely degrade the plasticity and machinability of metals, and nanoparticles, although they have the potential to improve strength while maintaining or even improving the plasticity of metals, are difficult to disperse uniformly in metal matrices. Here we show that a dense uniform dispersion of silicon carbide nanoparticles (14 per cent by volume) in magnesium can be achieved through a nanoparticle self-stabilization mechanism in molten metal. An enhancement of strength, stiffness, plasticity and high-temperature stability is simultaneously achieved, delivering a higher specific yield strength and higher specific modulus than almost all structural metals.

  12. From nanoparticles to fibres: effect of dispersion composition on fibre properties

    Energy Technology Data Exchange (ETDEWEB)

    Schirmer, Katharina S. U.; Esrafilzadeh, Dorna; Thompson, Brianna C.; Quigley, Anita F.; Kapsa, Robert M. I.; Wallace, Gordon G., E-mail: gwallace@uow.edu.au [University of Wollongong, ARC Centre for Electromaterials Science and Intelligent Polymer Research Institute (Australia)

    2015-06-15

    A polyvinyl alcohol (PVA)-stabilized polypyrrole nanodispersion has been optimised for conductivity and processability by decreasing the quantity of PVA before and after synthesis. A reduction of PVA before synthesis leads to the formation of particles with a slight increase in dry particle diameter (51 ± 6 to 63 ± 3 nm), and conversely a reduced hydrodynamic diameter. Conductivity of the dried nanoparticle films was not measureable after a reduction of PVA prior to synthesis. Using filtration of particles after synthesis, PVA content was sufficiently reduced to achieve dried thin film conductivity of 2 S cm{sup −1}, while the electroactivity of the dispersed particles remained unchanged. The as-synthesized and PVA-reduced polypyrrole particles were successfully spun into all-nanoparticle fibres using a wet-extrusion approach without the addition of any polymer or gel matrix. Using nanoparticles as a starting material is a novel approach, which allowed the production of macro-scale fibres that consisted entirely of polypyrrole nanoparticles. Fibres made from PVA-reduced polypyrrole showed higher electroactivity compared to fibres composed of the dispersion high in PVA. The mechanical properties of the fibres were also improved by reducing the amount of PVA present, resulting in a stronger, more ductile and less brittle fibre, which could find potential application in various fields.

  13. Synthesis and magnetic properties of bundled and dispersed Co3O4 nanowires

    International Nuclear Information System (INIS)

    Zhang, B.B.; Wang, P.F.; Xu, J.C.; Han, Y.B.; Jin, H.X.; Jin, D.F.; Peng, X.L.; Hong, B.; Li, J.; Yang, Y.T.; Gong, J.; Ge, H.L.; Wang, X.Q.

    2016-01-01

    Highlights: • Co 3 O 4 nanowires possessed the same diameter and the different interwires distance. • All samples possessed antiferromagnetism and superparamagnetism at high temperature. • The exchange bias effect was observed at low temperature. • The surface spin coupling restrained the surface effect of magnetic nanostructures. - Abstract: The magnetic Co 3 O 4 nanowires were synthesized using the templates of SBA-15, and then the well-dispersed nanowires (D-wires) were separated from the bundled ordered nanowires (B-wires) with the centrifugal technique. TEM images indicated that D-wires were highly dispersed Co 3 O 4 nanowires and B-wires existed in bundles. All samples possessed the antiferromagnetism and superparamagnetism at high temperature. After revealing the intrinsic magnetic properties of Co 3 O 4 nanowires with D-wires, the magnetic behavior of B-wires was discussed in detail, and then the magnetic interaction between neighboring nanowires could be deduced. The exchange bias effect from the body Co 3 O 4 antiferromagnetism and surface ferromagnetism was observed at low temperature. The magnetization of B-wires was higher than that of D-wires, which was attributed to the constraint of the surface spin coupling between the neighboring nanowires to the surface affect of nanostructures.

  14. From nanoparticles to fibres: effect of dispersion composition on fibre properties

    International Nuclear Information System (INIS)

    Schirmer, Katharina S. U.; Esrafilzadeh, Dorna; Thompson, Brianna C.; Quigley, Anita F.; Kapsa, Robert M. I.; Wallace, Gordon G.

    2015-01-01

    A polyvinyl alcohol (PVA)-stabilized polypyrrole nanodispersion has been optimised for conductivity and processability by decreasing the quantity of PVA before and after synthesis. A reduction of PVA before synthesis leads to the formation of particles with a slight increase in dry particle diameter (51 ± 6 to 63 ± 3 nm), and conversely a reduced hydrodynamic diameter. Conductivity of the dried nanoparticle films was not measureable after a reduction of PVA prior to synthesis. Using filtration of particles after synthesis, PVA content was sufficiently reduced to achieve dried thin film conductivity of 2 S cm −1 , while the electroactivity of the dispersed particles remained unchanged. The as-synthesized and PVA-reduced polypyrrole particles were successfully spun into all-nanoparticle fibres using a wet-extrusion approach without the addition of any polymer or gel matrix. Using nanoparticles as a starting material is a novel approach, which allowed the production of macro-scale fibres that consisted entirely of polypyrrole nanoparticles. Fibres made from PVA-reduced polypyrrole showed higher electroactivity compared to fibres composed of the dispersion high in PVA. The mechanical properties of the fibres were also improved by reducing the amount of PVA present, resulting in a stronger, more ductile and less brittle fibre, which could find potential application in various fields

  15. Synthesis and properties of ionic polyurethane dispersions: influence of polyol molecular weight

    International Nuclear Information System (INIS)

    Valipour Ebrahimi, M.; Barikani, M.; Mohammad Seyed Mohaghegh, S.

    2006-01-01

    A series of water dispersible polyurethanes containing carboxylate anion as the hydrophilic pendant group were prepared from toluene diisocyanate (TDI), 1,4- butanediol (1,4-BDO), dimethylol propionic acid and different molecular weight of polytetramethylene glycol . IR Spectroscopy was used to check the end of polymerization reaction and characterization of polymer. The effect of polytetramethylene glycol molecular weight was studied on the particle size distribution, contact angle, and mechanical and thermal properties of the emulsion-cast films. Average particle size of prepared polyurethane emulsions decreases with increasing the polytetramethylene glycol molecular weight. Tensile strength and hardness decrease and elongation-at-break and contact angle increase with increase of the polytetramethylene glycol molecular weight. Thermal property and thermal stability are also effected by variation of polytetramethylene glycol molecular weight. The thermal stability increases with increasing polytetramethylene glycol molecular weight. Glass transition temperature (T g ) moved toward the lower temperatures by increasing molecular weight of the polyol. Decrease in T g and tensile properties are interpreted in terms of the decrease in hard segments and the increase in chain flexibility and phase separation in high molecular weight polytetramethylene glycol based polyurethane

  16. Rheological properties of concentrated alumina slurries: influence of ph and dispersant agent

    International Nuclear Information System (INIS)

    Ewais, E.M.M.

    2004-01-01

    The relationship between the ph, the electrolyte concentrations and the rheological properties of high concentrated alumina slurries in aqueous medium is of great importance because it is considered to be the key to control the stability of the slurries from flocculation. Zeta potential of alumina slurries with and without Duramax C (dispersant agent) as a function of ph was studied. Two ph around the zero point of charge of alumina slurries were selected for the investigation of rheological properties. The rheological properties of aqueous alumina slurries with respect to different parameters, e.g.: viscosity, elastic modulus (storage modulus G) and viscous modulus (loss modulus G), were investigated. Viscosity measurements of the slurries as a function of Duramax C content at both ph 8.4 and 9.4) were used to determine the state of slurries. Three states of slurries, termed flocculated, partially de flocculated and fully de flocculated, were selected for further investigation. The viscosity of the three slurries at both ph as a function of shear rate was determined. Fully de flocculated slurry shows Newtonian behavior at all shear rates at both tested ph compared by the partial de flocculated and flocculated system. Results of investigation of G and G at ph of 9.4 as a function of applied stress explored the critical stress

  17. Dispersion Process and Effect of Oleic Acid on Properties of Cellulose Sulfate- Oleic Acid Composite Film

    Science.gov (United States)

    Chen, Guo; Zhang, Bin; Zhao, Jun

    2015-01-01

    The cellulose sulfate (CS) is a newly developed cellulose derivative. The work aimed to investigate the effect of oleic acid (OA) content on properties of CS-OA film. The process of oleic acid dispersion into film was described to evaluate its effect on the properties of the film. Among the formulations evaluated, the OA addition decreased the solubility and water vapor permeability of the CS-OA film. The surface contact angle changed from 64.2° to 94.0° by increasing CS/OA ratio from 1:0 to 1:0.25 (w/w). The TS increased with OA content below 15% and decreased with OA over 15%, but the ε decreased with higher OA content. The micro-cracking matrices and micro pores in the film indicated the condense structure of the film destroyed by the incorporation of oleic acid. No chemical interaction between the OA and CS was observed in the XRD and FTIR spectrum. Film formulation containing 2% (w/w) CS, 0.3% (w/w) glycerol and 0.3% (w/w) OA, showed good properties of mechanic, barrier to moisture and homogeneity.

  18. Effective properties of dispersed phase reinforced composite materials with perfect and imperfect interfaces

    Science.gov (United States)

    Han, Ru

    This thesis focuses on the analysis of dispersed phase reinforced composite materials with perfect as well as imperfect interfaces using the Boundary Element Method (BEM). Two problems of interest are considered, namely, to determine the limitations in the use of effective properties and the analysis of failure progression at the inclusion-matrix interface. The effective moduli (effective Young's modulus, effective Poisson's ratio, effective shear modulus, and effective bulk modulus) of composite materials can be determined at the mesoscopic level using three-dimensional parallel BEM simulations. By comparing the mesoscopic BEM results and the macroscopic results based on effective properties, limitations in the effective property approach can be determined. Decohesion is an important failure mode associated with fiber-reinforced composite materials. Analysis of failure progression at the fiber-matrix interface in fiber-reinforced composite materials is considered using a softening decohesion model consistent with thermodynamic concepts. In this model, the initiation of failure is given directly by a failure criterion. Damage is interpreted by the development of a discontinuity of displacement. The formulation describing the potential development of damage is governed by a discrete decohesive constitutive equation. Numerical simulations are performed using the direct boundary element method. Incremental decohesion simulations illustrate the progressive evolution of debonding zones and the propagation of cracks along the interfaces. The effect of decohesion on the macroscopic response of composite materials is also investigated.

  19. The complete genome sequence of Bacillus velezensis strain GH1-13 reveals agriculturally beneficial properties and a unique plasmid.

    Science.gov (United States)

    Kim, Sang Yoon; Song, Hajin; Sang, Mee Kyung; Weon, Hang-Yeon; Song, Jaekyeong

    2017-10-10

    The bacterial strain Bacillus velezensis GH1-13, isolated from rice paddy soil in Korea, has been shown to promote plant growth and have strong antagonistic activities against pathogens. Here, we report the complete genome sequence of GH1-13, revealing that it possesses a single 4,071,980-bp circular chromosome with 46.2% GC-content. The chromosome encodes 3,930 genes, and we have also identified a unique plasmid in the strain that encodes a further 104 genes (71,628bp and 31.7% GC-content). The genome was found to contain various enzyme-encoding operons, including indole-3-acetic acid (IAA) biosynthesis proteins, 2,3-butanediol dehydrogenase, various non-ribosomal peptide synthetases, and several polyketide synthases. These properties are responsible for the promotion of plant growth and the biosynthesis of secondary metabolites. They therefore have multiple beneficial effects that could be applied to agriculture. Through curing, we found that the unique plasmid of GH1-13 has important roles in the production of phytohormones, such as IAA, and in shaping phenotypic and physiological characteristics. The plasmid therefore likely influences the biological activities of GH1-13. The complete genome sequence of B. velezensis GH1-13 contributes to our understanding of this beneficial strain and will encourage research into its development for agricultural or biotechnological applications, enhancing productivity and crop quality. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Unique Reversible Crystal-to-Crystal Phase Transition – Structural and Functional Properties of Fused Ladder Thienoarenes

    KAUST Repository

    Abe, Yuichiro

    2017-08-15

    Donor-acceptor type molecules based on fused ladder thienoarenes, indacenodithiophene (IDT) and dithienocyclopenta-thienothiophene (DTCTT), coupled with benzothiadiazole, are prepared and their solid-state structures are investigated. They display a rich variety of solid phases ranging from amorphous glass states to crystalline states, upon changes in the central aromatic core and side group structures. Most notably, the DTCTT-based derivatives showed reversible crystal-to-crystal phase transitions in heating and cooling cycles. Unlike what has been seen in π−conjugated molecules variable temperature XRD revealed that structural change occurs continuously during the transition. A columnar self-assembled structure with slip-stacked π−π interaction is proposed to be involved in the solid-state. This research provides the evidence of unique structural behavior of the DTCTT-based molecules through the detailed structural analysis. This unique structural transition paves the way for these materials to have self-healing of crystal defects, leading to improved optoelectronic properties.

  1. Unique Reversible Crystal-to-Crystal Phase Transition – Structural and Functional Properties of Fused Ladder Thienoarenes

    KAUST Repository

    Abe, Yuichiro; Savikhin, Victoria; Yin, Jun; Grimsdale, Andrew C.; Soci, Cesare; Toney, Michael F.; Lam, Yeng Ming

    2017-01-01

    Donor-acceptor type molecules based on fused ladder thienoarenes, indacenodithiophene (IDT) and dithienocyclopenta-thienothiophene (DTCTT), coupled with benzothiadiazole, are prepared and their solid-state structures are investigated. They display a rich variety of solid phases ranging from amorphous glass states to crystalline states, upon changes in the central aromatic core and side group structures. Most notably, the DTCTT-based derivatives showed reversible crystal-to-crystal phase transitions in heating and cooling cycles. Unlike what has been seen in π−conjugated molecules variable temperature XRD revealed that structural change occurs continuously during the transition. A columnar self-assembled structure with slip-stacked π−π interaction is proposed to be involved in the solid-state. This research provides the evidence of unique structural behavior of the DTCTT-based molecules through the detailed structural analysis. This unique structural transition paves the way for these materials to have self-healing of crystal defects, leading to improved optoelectronic properties.

  2. THE STUDYING OF COLLOIDAL-CHEMICAL PROPERTIES OF CLAY MINERALS DISPERSIONS

    Directory of Open Access Journals (Sweden)

    A. F. Tymchuk

    2015-02-01

    Full Text Available The element structure is studied, the microscopic analysis of fine-dispersed min­eral systems (ground sediments of a mouth of the river Danube is carried out. The sedimentation process of clay minerals dispersions in solutions of surfactants and macromolecular substances is studied. Concentration intervals of stabilization of investigating dispersions were defined.

  3. Diffraction properties study of reflection volume holographic grating in dispersive photorefractive material under ultra-short pulse readout

    Energy Technology Data Exchange (ETDEWEB)

    Yi Yingyan; Liu Deming; Liu Hairong, E-mail: yiyingyan0410@163.com [Wuhan National Laboratory for Optoelectronics, School of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China)

    2011-02-01

    Based on the modified Kogelnik diffraction efficiency equation, we study the diffraction intensity spectrum and the total diffraction efficiency of reflection volume holographic gratings in photorefractive media. Taking photorefractive LiNbO{sub 3} crystal as an example, the effect of the grating parameters and the pulse width on the diffraction properties is presented under the influence of crystal material dispersion. Under the combined effects, the diffraction pulse profiles and the total diffraction efficiency are compared with and without crystal material dispersion. The results show that the dispersion will decrease the diffraction intensity. Moreover, when pulse width is smaller or the grating spacing and the grating thickness are larger, the influence of dispersion on diffraction is large. The results of our paper can be used in pulse shaping applications.

  4. Dispersion of dielectric permittivity and magnetic properties of solid solution PZT–PFT

    Directory of Open Access Journals (Sweden)

    Skulski Ryszard

    2015-09-01

    Full Text Available In this paper we present the results of investigations into ceramic samples of solid solution (1-x(PbZr0.53Ti0.47O3- x(PbFe0.5Ta0.503 (i.e. (1-xPZT-xPFT with x = 0.25, 0.35 and 0.45. We try to find the relation between the character of dielectric dispersion at various temperatures and the composition of this solution. We also describe the magnetic properties of investigated samples. With increasing the content of PFT also mass magnetization and mass susceptibility increase (i.e. magnetic properties are more pronounced at every temperature. The temperature dependences of mass magnetization and re­ciprocal of mass susceptibility have similar runs for all the compositions. However, our magnetic investigations exhibit weak antiferromagnetic ordering instead of the ferromagnetic one at room temperature. We can also say that up to room tempera­ture any magnetic phase transition has not occurred. It may be a result of the conditions of the technological process during producing our PZT-PFT ceramics.

  5. Theoretical study of phonon dispersion, elastic, mechanical and thermodynamic properties of barium chalcogenides

    Science.gov (United States)

    Musari, A. A.; Orukombo, S. A.

    2018-03-01

    Barium chalcogenides are known for their high-technological importance and great scientific interest. Detailed studies of their elastic, mechanical, dynamical and thermodynamic properties were carried out using density functional theory and plane-wave pseudo potential method within the generalized gradient approximation. The optimized lattice constants were in good agreement when compared with experimental data. The independent elastic constants, calculated from a linear fit of the computed stress-strain function, were used to determine the Young’s modulus (E), bulk modulus (B), shear modulus (G), Poisson’s ratio (σ) and Zener’s anisotropy factor (A). Also, the Debye temperature and sound velocities for barium chalcogenides were estimated from the three independent elastic constants. The calculations of phonon dispersion showed that there are no negative frequencies throughout the Brillouin zone. Hence barium chalcogenides have dynamically stable NaCl-type crystal structure. Finally, their thermodynamic properties were calculated in the temperature range of 0-1000 K and their constant-volume specific heat capacities at room-temperature were reported.

  6. Thermal characterization of static and dynamical properties of the confined molecular systems interacting through dispersion force.

    Science.gov (United States)

    Ramos, Sergio Luis L M; Ogino, Michihiko; Oguni, Masaharu

    2015-01-28

    We investigated the thermal properties of liquid methylcyclohexane and racemic sec-butylcyclohexane, as representatives of a molecular system with only dispersion-force intermolecular interactions, confined in the pores (thickness/diameter d = 12, 6, 1.1 nm) of silica gels by adiabatic calorimetry. The results imply a heterogeneous picture for molecular aggregate under confinement consisting of an interfacial region and an inner pore one. In the vicinity of a glass-transition temperature T(g,bulk) of bulk liquid, two distinguishable relaxation phenomena were observed for the confined systems and their origins were attributed to the devitrification, namely glass transition, processes of (1) a layer of interfacial molecules adjacent to the pore walls and (2) the molecules located in the middle of the pore. A third glass-transition phenomenon was observed at lower temperatures and ascribed to a secondary relaxation process. The glass transition of the interfacial-layer molecules was found to proceed at temperatures rather above T(g,bulk), whereas that of the molecules located in the inner pore region occurred at temperatures below T(g,bulk). We discuss the reason why the molecules located in different places in the pores reveal the respectively different dynamical properties.

  7. Unique Cell Adhesion and Invasion Properties of Yersinia enterocolitica O:3, the Most Frequent Cause of Human Yersiniosis

    Science.gov (United States)

    Uliczka, Frank; Pisano, Fabio; Schaake, Julia; Stolz, Tatjana; Rohde, Manfred; Fruth, Angelika; Strauch, Eckhard; Skurnik, Mikael; Batzilla, Julia; Rakin, Alexander; Heesemann, Jürgen; Dersch, Petra

    2011-01-01

    Many enteric pathogens are equipped with multiple cell adhesion factors which are important for host tissue colonization and virulence. Y. enterocolitica, a common food-borne pathogen with invasive properties, uses the surface proteins invasin and YadA for host cell binding and entry. In this study, we demonstrate unique cell adhesion and invasion properties of Y. enterocolitica serotype O:3 strains, the most frequent cause of human yersiniosis, and show that these differences are mainly attributable to variations affecting the function and expression of invasin in response to temperature. In contrast to other enteric Yersinia strains, invasin production in O:3 strains is constitutive and largely enhanced compared to other Y. enterocolitica serotypes, in which invA expression is temperature-regulated and significantly reduced at 37°C. Increase of invasin levels is caused by (i) an IS1667 insertion into the invA promoter region, which includes an additional promoter and RovA and H-NS binding sites, and (ii) a P98S substitution in the invA activator protein RovA rendering the regulator less susceptible to proteolysis. Both variations were shown to influence bacterial colonization in a murine infection model. Furthermore, we found that co-expression of YadA and down-regulation of the O-antigen at 37°C is required to allow efficient internalization by the InvA protein. We conclude that even small variations in the expression of virulence factors can provoke a major difference in the virulence properties of closely related pathogens which may confer better survival or a higher pathogenic potential in a certain host or host environment. PMID:21750675

  8. Easily Dispersible NiFe2O4/RGO Composite for Microwave Absorption Properties in the X-Band

    Science.gov (United States)

    Bateer, Buhe; Zhang, Jianjao; Zhang, Hongchen; Zhang, Xiaochen; Wang, Chunyan; Qi, Haiqun

    2018-01-01

    Composites with good dispersion and excellent microwave absorption properties have important applications. Therefore, an easily dispersible NiFe2O4/reduced graphene oxide (RGO) composite has been prepared conveniently through a simple hydrothermal method. Highly crystalline, small size (about 7 nm) monodispersed NiFe2O4 nanoparticles (NPs) are evenly distributed on the surface of RGO. The microwave absorbability revealed that the NiFe2O4/RGO composite exhibits excellent microwave absorption properties in the X-band (8-12 GHz), and the minimum reflection loss of the NiFe2O4/RGO composite is -27.7 dB at 9.2 GHz. The NiFe2O4/RGO composite has good dispersibility in nonpolar solvent, which facilitates the preparation of stable commercial microwave absorbing coatings. It can be a promising candidate for lightweight microwave absorption materials in many application fields.

  9. A unified inversion scheme to process multifrequency measurements of various dispersive electromagnetic properties

    Science.gov (United States)

    Han, Y.; Misra, S.

    2018-04-01

    Multi-frequency measurement of a dispersive electromagnetic (EM) property, such as electrical conductivity, dielectric permittivity, or magnetic permeability, is commonly analyzed for purposes of material characterization. Such an analysis requires inversion of the multi-frequency measurement based on a specific relaxation model, such as Cole-Cole model or Pelton's model. We develop a unified inversion scheme that can be coupled to various type of relaxation models to independently process multi-frequency measurement of varied EM properties for purposes of improved EM-based geomaterial characterization. The proposed inversion scheme is firstly tested in few synthetic cases in which different relaxation models are coupled into the inversion scheme and then applied to multi-frequency complex conductivity, complex resistivity, complex permittivity, and complex impedance measurements. The method estimates up to seven relaxation-model parameters exhibiting convergence and accuracy for random initializations of the relaxation-model parameters within up to 3-orders of magnitude variation around the true parameter values. The proposed inversion method implements a bounded Levenberg algorithm with tuning initial values of damping parameter and its iterative adjustment factor, which are fixed in all the cases shown in this paper and irrespective of the type of measured EM property and the type of relaxation model. Notably, jump-out step and jump-back-in step are implemented as automated methods in the inversion scheme to prevent the inversion from getting trapped around local minima and to honor physical bounds of model parameters. The proposed inversion scheme can be easily used to process various types of EM measurements without major changes to the inversion scheme.

  10. Creep and residual mechanical properties of cast superalloys and oxide dispersion strengthened alloys

    Science.gov (United States)

    Whittenberger, J. D.

    1981-01-01

    Tensile, stress-rupture, creep, and residual tensile properties after creep testing were determined for two typical cast superalloys and four advanced oxide dispersion strengthened (ODS) alloys. The superalloys examined included the nickel-base alloy B-1900 and the cobalt-base alloy MAR-M509. The nickel-base ODS MA-757 (Ni-16CR-4Al-0.6Y2O3 and the iron-base ODS alloy MA-956 (Fe-20Cr-5Al-0.8Y2O3) were extensively studied, while limited testing was conducted on the ODS nickel-base alloys STCA (Ni-16Cr-4.5Al-2Y2O3) with a without Ta and YD-NiCrAl (Ni-16Cr-5Al-2Y2O3). Elevated temperature testing was conducted from 114 to 1477 K except for STCA and YD-NiCrAl alloys, which were only tested at 1366 K. The residual tensile properties of B-1900 and MAR-M509 are not reduced by prior creep testing (strains at least up to 1 percent), while the room temperature tensile properties of ODS nickel-base alloys can be reduced by small amounts of prior creep strain (less than 0.5 percent). The iron-base ODS alloy MA-956 does not appear to be susceptible to creep degradation at least up to strains of about 0.25 percent. However, MA-956 exhibits unusual creep behavior which apparently involves crack nucleation and growth.

  11. Effect of ionic liquids on the dispersion of zinc oxide and silica nanoparticles, vulcanisation behaviour and properties of NBR composites

    Directory of Open Access Journals (Sweden)

    M. Maciejewska

    2014-12-01

    Full Text Available The aim of this work was to study the activity of several alkylpyrrolidinium, alkylpyridinium, alkylpiperidinium and benzylimidazolium ionic liquids (ILs for the purpose of improving the dispersion degree of vulcanisation activator and filler nanoparticles in the acrylonitrile-butadiene elastomer (NBR. The effect of the ionic liquids on the vulcanisation kinetics of the rubber compounds, crosslink density and mechanical properties of the vulcanisates and their resistance to thermo-oxidative and UV ageing was studied. The use of ionic liquids allowed for a homogeneous dispersion of nanoparticles in the elastomer without detrimental effects on the vulcanisation process. The physical properties and the thermal stability of the obtained vulcanisates were significantly improved. Ionic liquids increased the crosslink density of the vulcanisates and their damping properties. Pirydinium and piperidinium hexafluorophosphates were most effective at increasing the crosslink density and improving the properties of NBR composites.

  12. Dependence of the clustering properties of galaxies on stellar velocity dispersion in the Main galaxy sample of SDSS DR10

    Science.gov (United States)

    Deng, Xin-Fa; Song, Jun; Chen, Yi-Qing; Jiang, Peng; Ding, Ying-Ping

    2014-08-01

    Using two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10), we investigate the dependence of the clustering properties of galaxies on stellar velocity dispersion by cluster analysis. It is found that in the luminous volume-limited Main galaxy sample, except at r=1.2, richer and larger systems can be more easily formed in the large stellar velocity dispersion subsample, while in the faint volume-limited Main galaxy sample, at r≥0.9, an opposite trend is observed. According to statistical analyses of the multiplicity functions, we conclude in two volume-limited Main galaxy samples: small stellar velocity dispersion galaxies preferentially form isolated galaxies, close pairs and small group, while large stellar velocity dispersion galaxies preferentially inhabit the dense groups and clusters. However, we note the difference between two volume-limited Main galaxy samples: in the faint volume-limited Main galaxy sample, at r≥0.9, the small stellar velocity dispersion subsample has a higher proportion of galaxies in superclusters ( n≥200) than the large stellar velocity dispersion subsample.

  13. Unique Path Partitions

    DEFF Research Database (Denmark)

    Bessenrodt, Christine; Olsson, Jørn Børling; Sellers, James A.

    2013-01-01

    We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions.......We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions....

  14. Effects of gold nanoparticles on the electro-optical properties of a polymer dispersed liquid crystal

    Science.gov (United States)

    Hinojosa, A.; Shive, C.; Sharma, Suresh

    2010-03-01

    We have studied the electro-optical properties of a polymer-dispersed liquid crystal (PDLC) as functions of relative concentrations of gold nanoparticles. PDLC samples were synthesized between indium-tin-oxide (ITO) coated glass slides, separated by SiO2 spacers, by using liquid crystal E44, a monofunctional acrylic oligomer (CN135), and a tetrafunctional crosslinker (SR295). A UV photoinitiator (SR1124) was used to facilitate the curing of the monomer exposed to UV radiation from a Hg spectral lamp. A He-Ne laser was used to measure optical transmission through the PDLC as a function of applied ac electric field (1 kHz). The PDLC without gold nanoparticles shows the expected behavior; transmission through the PDLC increases from a minimum (opaque) to a maximum (transparent) with increasing electric field. The electro-optical behavior of the PDLC is altered significantly (e. g., relatively low switching field) upon addition of relatively low concentrations of gold nanoparticles into the starting PDLC syrup. We present electro-optical data as functions of gold nanoparticle concentration and discuss possible mechanism to understand our results.

  15. The effect of spherical nanoparticles on rheological properties of bi-dispersed magnetorheological fluids

    Science.gov (United States)

    Kannappan, K. Thiruppathi; Laherisheth, Zarana; Parekh, Kinnari; Upadhyay, R. V.

    2015-06-01

    In the present investigation, the rheological properties of bi-dispersed magnetorheological (MR) fluid based on Fe3O4 nanosphere and microsphere of iron particles are experimentally investigated. The MR fluid is prepared by substituting nanosphere of 40nm Fe3O4 particles in MR fluids having microsphere iron particles (7-8 μm). Three different weight fractions (0%, 1% and 3%) of nanosphere-microsphere MR fluids are synthesized. In the absence of the magnetic field, substitution of magnetic nanosphere decreases the viscosity lower than without substituted sample at high as well as low shear rate. Upon the application of the magnetic field, the particles align along the direction of the field, which promotes the yield stress. Here too the yield stress value decreases with magnetic nanosphere substitution. This behaviour is explain based on the inter-particle interaction as well as formation of nanosphere cloud around the magnetic microsphere, which effectively reduces the viscosity and works as weak point when chains are formed. Variation of dynamic yield stress with magnetic field is explained using microscopic model. In any event such fluid does not sediment and is not abrasive so it could be useful if not too high yield stress is needed.

  16. Thermophysical properties of heat-treated U-7Mo/Al dispersion fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Tae Won; Kim, Yeon Soo; Park, Jong Man; Lee, Kyu Hong; Kim, Sunghwan; Lee, Chong Tak; Yang, Jae Ho; Oh, Jang Soo; Sohn, Dong-Seong

    2018-04-01

    In this study, the effects of interaction layer (IL) on thermophysical properties of U-7Mo/Al dispersion fuel were examined. Microstructural analyses revealed that ILs were formed uniformly on U-Mo particles during heating of U-7Mo/Al samples. The IL volume fraction was measured by applying image analysis methods. The uranium loadings of the samples were calculated based on the measured meat densities at 298 K. The density of the IL was estimated by using the measured density and IL volume fraction. Thermal diffusivity and heat capacity of the samples after the heat treatment were measured as a function of temperature and volume fractions of U-Mo and IL. The thermal conductivity of IL-formed U-7Mo/Al was derived by using the measured thermal diffusivity, heat capacity, and density. The thermal conductivity obtained in the present study was lower than that predicted by the modified Hashin–Shtrikman model due to the theoretical model’s inability to consider the thermal resistance at interfaces between the meat constituents.

  17. Thermophysical properties of heat-treated U-7Mo/Al dispersion fuel

    Science.gov (United States)

    Cho, Tae Won; Kim, Yeon Soo; Park, Jong Man; Lee, Kyu Hong; Kim, Sunghwan; Lee, Chong Tak; Yang, Jae Ho; Oh, Jang Soo; Sohn, Dong-Seong

    2018-04-01

    In this study, the effects of interaction layer (IL) on thermophysical properties of U-7Mo/Al dispersion fuel were examined. Microstructural analyses revealed that ILs were formed uniformly on U-Mo particles during heating of U-7Mo/Al samples. The IL volume fraction was measured by applying image analysis methods. The uranium loadings of the samples were calculated based on the measured meat densities at 298 K. The density of the IL was estimated by using the measured density and IL volume fraction. Thermal diffusivity and heat capacity of the samples after the heat treatment were measured as a function of temperature and volume fractions of U-Mo and IL. The thermal conductivity of IL-formed U-7Mo/Al was derived by using the measured thermal diffusivity, heat capacity, and density. The thermal conductivity obtained in the present study was lower than that predicted by the modified Hashin-Shtrikman model due to the theoretical model's inability to consider the thermal resistance at interfaces between the meat constituents.

  18. Microstructure and Mechanical Property of 12Cr Oxide Dispersion Strengthened Steel

    Science.gov (United States)

    Xu, Haijian; Lu, Zheng; Jia, Chunyan; Gao, Hao; Liu, Chunming

    2016-03-01

    Nanostructured oxide dispersion strengthened (ODS) steels with nominal compositions (wt%): Fe-12Cr-2W-0.3Ti-0.3Y2O3 were produced by mechanical alloying and hot isostatic pressing. The microstructure was characterized by means of electron microscopy (EBSD, TEM and HRTEM) and the hardness and the tensile properties at different temperatures were measured. The results showed that the ultimate tensile strength of the fabricated 12Cr-ODS steel reached nearly 1,100 MPa at room temperature and maintained around 340 MPa at 700°C. Nano-oxide particles with size ranging from several nm to 30 nm and the number density was 3.6 × 1020/m3 were observed by TEM. Following heat treatment, including normalizing at 1,100°C for 1 h and tempering at 750°C for 2 h, the average grain size was a little decreased. The number of nano-oxide particles increased and the number density was 8.9 × 1020/m3. Specimens showed much higher ductility and there was a slight increase of ultimate tensile strength and Vickers hardness at the same time.

  19. New insights into the reduction systems of plastidial thioredoxins point out the unique properties of thioredoxin z from Arabidopsis.

    Science.gov (United States)

    Bohrer, Anne-Sophie; Massot, Vincent; Innocenti, Gilles; Reichheld, Jean-Philippe; Issakidis-Bourguet, Emmanuelle; Vanacker, Hélène

    2012-11-01

    In plants, thioredoxins (TRX) constitute a large protein disulphide oxidoreductase family comprising 10 plastidial members in Arabidopsis thaliana and subdivided in five types. The f- and m-types regulate enzymes involved mainly in carbon metabolism whereas the x, y, and z types have an antioxidant function. The reduction of TRXm and f in chloroplasts is performed in the light by ferredoxin:thioredoxin reductase (FTR) that uses photosynthetically reduced ferredoxin (Fd) as a reductant. The reduction system of Arabidopsis TRXx, y, and z has never been demonstrated. Recently, a gene encoding an atypical plastidial NADPH-dependent TRX reductase (NTRC) was found. In the present study, gene expression analysis revealed that both reductases are expressed in all organs of Arabidopsis and could potentially serve as electron donors to plastidial TRX. This ability was tested in vitro either with purified NTRC in presence of NADPH or with a light-driven reconstituted system comprising thylakoids and purified Fd and FTR. The results demonstrate that FTR reduces the x and y TRX isoforms but not the recently identified TRXz. Moreover, the results show that NTRC cannot be an efficient alternative reducing system, neither for TRXz nor for the other plastidial TRX. The data reveal that TRXf, m, x, and y, known as redox regulators in the chloroplast, have also the ability to reduce TRXz in vitro. Overall, the present study points out the unique properties of TRXz among plastidial TRX.

  20. Unique in vivo properties of olfactory ensheathing cells that may contribute to neural repair and protection following spinal cord injury

    Science.gov (United States)

    Kocsis, Jeffery D.; Lankford, Karen L.; Sasaki, Masanori; Radtke, Christine

    2009-01-01

    Olfactory ensheathing cells (OECs) are specialized glial cells that guide olfactory receptor axons from the nasal mucosa into the brain where they make synaptic contacts in the olfactory bulb. While a number of studies have demonstrated that in vivo transplantation of OECs into injured spinal cord results in improved functional outcome, precise cellular mechanisms underlying this improvement are not fully understood. Current thinking is that OECs can encourage axonal regeneration, provide trophic support for injured neurons and for angiogenesis, and remyelinate axons. However, Schwann cell (SC) transplantation also results in significant functional improvement in animal models of spinal cord injury. In culture SCs and OECs share a number of phenotypic properties such as expression of the low affinity NGF receptor (p75). An important area of research has been to distinguish potential differences in the in vivo behavior of OECs and SCs to determine if one cell type may offer greater advantage as a cellular therapeutic candidate. In this review we focus on several unique features of OECs when they are transplanted into the spinal cord. PMID:19429149

  1. A Novel Carbohydrate-binding Module from Sugar Cane Soil Metagenome Featuring Unique Structural and Carbohydrate Affinity Properties*

    Science.gov (United States)

    Campos, Bruna Medeia; Alvarez, Thabata Maria; Zanphorlin, Letícia Maria; Ematsu, Gabriela Cristina; Barud, Hernane; Polikarpov, Igor; Ruller, Roberto; Gilbert, Harry J.; Zeri, Ana Carolina de Mattos; Squina, Fabio Marcio

    2016-01-01

    Carbohydrate-binding modules (CBMs) are appended to glycoside hydrolases and can contribute to the degradation of complex recalcitrant substrates such as the plant cell wall. For application in bioethanol production, novel enzymes with high catalytic activity against recalcitrant lignocellulosic material are being explored and developed. In this work, we report the functional and structural study of CBM_E1, which was discovered through a metagenomics approach and is the founding member of a novel CBM family, CBM81. CBM_E1, which is linked to an endoglucanase, displayed affinity for mixed linked β1,3-β1,4-glucans, xyloglucan, Avicel, and cellooligosaccharides. The crystal structure of CBM_E1 in complex with cellopentaose displayed a canonical β-sandwich fold comprising two β-sheets. The planar ligand binding site, observed in a parallel orientation with the β-strands, is a typical feature of type A CBMs, although the expected affinity for bacterial crystalline cellulose was not detected. Conversely, the binding to soluble glucans was enthalpically driven, which is typical of type B modules. These unique properties of CBM_E1 are at the interface between type A and type B CBMs. PMID:27621314

  2. Sensing properties of pristine boron nitride nanostructures towards alkaloids: A first principles dispersion corrected study

    Science.gov (United States)

    Roondhe, Basant; Dabhi, Shweta D.; Jha, Prafulla K.

    2018-05-01

    To understand the underlying physics behind the interaction of biomolecules with the nanomaterials to use them practically as bio-nanomaterials is very crucial. A first principles calculation under the frame work of density functional theory is executed to investigate the electronic structures and binding properties of alkaloids (Caffeine and Nicotine) over single walled boron nitride nanotube (BNNT) and boron nitride nanoribbon (BNNR) to determine their suitability towards filtration or sensing of these molecules. We have also used GGA-PBE scheme with the inclusion of Van der Waals (vdW) interaction based on DFT-D2. Increase in the accuracy by incorporating the dispersion correction in the calculation is observed for the long range Van der Waals interaction. Binding energy range of BNNT and BNNR with both alkaloids have been found to be -0.35 to -0.76 eV and -0.45 to -0.91 eV respectively which together with the binding distance shows physisorption binding of these molecules to the both nanostructures. The transfer of charge between the BN nanostructures and the adsorbed molecule has also been analysed by using Lowdin charge analysis. The sensitivity of both nanostructures BNNT and BNNR towards both alkaloids is observed through electronic structure calculations, density of states and quantum conductance. The binding of both alkaloids with BNNR is stronger. The analysis of the calculated properties suggests absence of covalent interaction between the considered species (BNNT/BNNR) and alkaloids. The study may be useful in designing the boron nitride nanostructure based sensing device for alkaloids.

  3. Unique Dispersal of the Changjiang-Diluted Water Plume in the East China Sea Revealed from Satellite Monitoring of Colored Dissolved Organic Matter (CDOM)

    OpenAIRE

    Hiroaki Sasaki; Yasushi Gomi; Takamasa Asai; Masashi Shibata; Yoko Kiyomoto; Kazumaro Okamura; Kou Nishiuchi; Toru Hasegawa; Haruya Yamada

    2014-01-01

    The optical properties of colored dissolved organic matter (CDOM) in the Changjiang (Yangtze River) plume water were investigated during the summer of 2009 and 2010. The absorption coefficient of CDOM at 325 nm (aCDOM) increased inversely with decreasing sea-surface salinity (SSS), implying that aCDOM can be used as a natural tracer of Changjiang-diluted water (CDW). This aCDOM vs. SSS relationship, however, differed between 2009 and 2010. For mapping the CDW plume, the aCDOM was retrieved fr...

  4. Geometrical optimization of the transmission and dispersion properties of arrayed waveguide gratings using two stigmatic point mountings.

    Science.gov (United States)

    Muñoz, P; Pastor, D; Capmany, J; Martínez, A

    2003-09-22

    In this paper, the procedure to optimize flat-top Arrayed Waveguide Grating (AWG) devices in terms of transmission and dispersion properties is presented. The systematic procedure consists on the stigmatization and minimization of the Light Path Function (LPF) used in classic planar spectrograph theory. The resulting geometry arrangement for the Arrayed Waveguides (AW) and the Output Waveguides (OW) is not the classical Rowland mounting, but an arbitrary geometry arrangement. Simulation using previous published enhanced modeling show how this geometry reduces the passband ripple, asymmetry and dispersion, in a design example.

  5. Influence of the silicon content on the core corrosion properties of dispersion type fuel plates

    International Nuclear Information System (INIS)

    Calvo, C.; Saenz de Tejada, L. M.; Diaz Diaz, J.

    1969-01-01

    A new process to produce aluminium base dispersion type fuel plates has been developed at the Spanish JEN (Junta de Energia Nuclear). The dispersed fuel material is obtained by an aluminothermic process to render a stoichiometric cermet of UAI 3 and AI 2 O 3 according to the reaction. (Author)

  6. Structural, microstructural and electrochemical properties of dispersed-type polymer nanocomposite films

    Science.gov (United States)

    Arya, Anil; Sharma, A. L.

    2018-01-01

    Free-standing solid polymer nanocomposite (PEO-PVC)  +  LiPF6-TiO2 films have been prepared through a standard solution-cast technique. The improvement in structural, microstructural and electrochemical properties has been observed on the dispersion of nanofiller in polymer salt complex. X-ray diffraction studies clearly reflect the formation of complex formation, as no corresponding salt peak appeared in the diffractograms. The Fourier transform infrared analysis suggested clear and convincing evidence of polymer-ion, ion-ion and polymer-ion-nanofiller interaction. The highest ionic conductivity of the prepared solid polymer electrolyte (SPE) films is ~5  ×  10-5 S cm-1 for 7 wt.% TiO2. The linear sweep voltammetry provides the electrochemical stability window of the prepared SPE films, about ~3.5 V. The ion transference number has been estimated, t ion  =  0.99 through the DC polarization technique. Dielectric spectroscopic studies were performed to understand the ion transport process in polymer electrolytes. All solid polymer electrolytes possess good thermal stability up to 300 °C. Differential scanning calorimetry analysis confirms the decrease of the melting temperature and signal of glass transition temperature with the addition of nanofiller, which indicates the decrease of crystallinity of the polymer matrix. An absolute correlation between diffusion coefficient (D), ion mobility (µ), number density (n), double-layer capacitance (C dl), glass transition temperature, melting temperature (T m), free ion area (%) and conductivity (σ) has been observed. A convincing model to study the role of nanofiller in a polymer salt complex has been proposed, which supports the experimental findings. The prepared polymer electrolyte system with significant ionic conductivity, high ionic transference number, and good thermal and voltage stability could be suggested as a potential candidate as electrolyte cum separator for the fabrication of a

  7. Microstructures and mechanical properties of 9Cr oxide dispersion strengthened steel produced by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Rui [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China); School of Metallurgy, Northeastern University, Shenyang 110819 (China); Lu, Zheng, E-mail: luz@atm.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China); Lu, Chenyang; Li, Zhengyuan [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China); Ding, Xueyong [School of Metallurgy, Northeastern University, Shenyang 110819 (China); Liu, Chunming [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819 (China)

    2017-02-15

    Highlights: • A 9Cr-ODS steel was produced by mechanical alloying and spark plasma sintering. • Bimodal grain size distribution was observed. • Formation mechanism of bimodal grain size distribution was discussed. • The size and number density of nanoscale particles were obtained by SAXS and HRTEM. • The contribution of nano-sized particles to yield strength is dominating. - Abstract: 9Cr oxide dispersion strengthened (ODS) steel was fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). The nano-sized particles, grain size distribution and mechanical properties of 9Cr-ODS steel sintered at 950 °C were studied by synchrotron radiation small angle X-ray scattering (SAXS), high-resolution transmission electron microscopy (HRTEM), electron backscatter diffraction (EBSD) and tensile experiment. The results showed that bimodal grain size distribution in the matrix is observed, which is attributed to the heterogeneous recrystallization process during the SPS. High-density nano-sized Y{sub 2}Ti{sub 2}O{sub 7} and some large oxides of Cr{sub 2}Mn(Ti)O{sub 4} are formed in 9Cr-ODS steel. The number density and average size of Y{sub 2}Ti{sub 2}O{sub 7} obtained from SAXS are 4.72 × 10{sup 22}/m{sup 3} and 4.4 nm, respectively. The yield strengths of 9Cr-ODS steel fabricated by SPS are compared with the typical 9Cr-ODS steel produced by HIP.

  8. Plutonium uniqueness

    International Nuclear Information System (INIS)

    Silver, G.L.

    1984-01-01

    A standard is suggested against which the putative uniqueness of plutonium may be tested. It is common folklore that plutonium is unique among the chemical elements because its four common oxidation states can coexist in the same solution. Whether this putative uniqueness appears only during transit to equilibrium, or only at equilibrium, or all of the time, is not generally made clear. But while the folklore may contain some truth, it cannot be put to test until some measure of 'uniqueness' is agreed upon so that quantitative comparisons are possible. One way of measuring uniqueness is as the magnitude of the product of the mole fractions of the element at equilibrium. A 'coexistence index' is defined and discussed. (author)

  9. Fast high-temperature consolidation of Oxide-Dispersion Strengthened (ODS) steels: process, microstructure, precipitation, properties

    International Nuclear Information System (INIS)

    Boulnat, Xavier

    2014-01-01

    This work aims to lighten the understanding of the behavior of a class of metallic materials called Oxide-Dispersion Strengthened (ODS) ferritic steels. ODS steels are produced by powder metallurgy with various steps including atomization, mechanical alloying and high-temperature consolidation. The consolidation involves the formation of nanoparticles in the steel and various evolutions of the microstructure of the material that are not fully understood. In this thesis, a novel consolidation technique assisted by electric field called 'Spark Plasma Sintering' (SPS) or 'Field-Assisted Sintering Technique' (FAST) was assessed. Excellent mechanical properties were obtained by SPS, comparable to those of conventional hot isostatic pressed (HIP) materials but with much shorter processing time. Also, a broad range of microstructures and thus of tensile strength and ductility were obtained by performing SPS on either milled or atomized powder at different temperatures. However, SPS consolidation failed to avoid heterogeneous microstructure composed of ultrafine-grained regions surrounded by micron grains despite of the rapid consolidation kinetics. A multi-scale characterization allowed to understand and model the evolution of this complex microstructure. An analytical evaluation of the contributing mechanisms can explain the appearance of the complex grain structure and its thermal stability during further heat treatments. Inhomogeneous distribution of plastic deformation in the powder is argued to be the major cause of heterogeneous recrystallization and further grain growth during hot consolidation. Even if increasing the solute content of yttrium, titanium and oxygen does not impede abnormal growth, it permits to control the fraction and the size of the retained ultrafine grains, which is a key-factor to tailor the mechanical properties. Since precipitation through grain boundary pinning plays a significant role on grain growth, a careful

  10. Importance of intrinsic properties of dense caseinate dispersions for structure formation

    NARCIS (Netherlands)

    Manski, J.M.; Riemsdijk, van L.E.; Goot, van der A.J.; Boom, R.M.

    2007-01-01

    Rheological measurements of dense calcium caseinate and sodium caseinate dispersions (15%) provided insight into the factors determining shear-induced structure formation in caseinates. Calcium caseinate at a sufficiently high concentration (30%) was shown to form highly anisotropic structures

  11. Hierarchical structures and phase nucleation and growth during pressure-induced crystallization of polypropylene containing dispersion of nanoclay: The impact on physical and mechanical properties

    International Nuclear Information System (INIS)

    Misra, R.D.K.; Yuan, Q.; Chen, J.; Yang, Y.

    2010-01-01

    The objective of this study is to describe the evolution of structure and phases during pressure-induced crystallization of polymers containing dispersion of nanoparticles, in the pressure range of 0.1-200 MPa. The model material for nanoparticles is nanoclay and the model polymer is polypropylene, which can potentially form several crystalline phases. While the phase selection in polypropylene is dictated by pressure and temperature, however, the introduction of nanoparticles alters the nucleation and growth of phases via nanoparticle interface driven evolution. To delineate and separate the effects of applied crystallization pressure from nanoparticle effects, a relative comparison is made between neat polypropylene and polypropylene containing dispersion of nanoclay under similar experimental conditions. The significant finding is that nanoclay interacts with the host polypropylene in a manner such that it alters the structural morphology of α- and γ-crystals of polypropylene. Furthermore, nanoclay promotes the formation of γ-phase at ambient pressure suggesting its role as structure and morphology director in the stabilization of the less accessible γ-phase, and with the possibility of epitaxial growth that enhances toughness. The equilibrium melting point measurements point to thermodynamic interaction between nanoclay and polypropylene, which is supported by the change in glass transition temperature. Thus, the two components, nanoclay and pressure, together provide a unique opportunity to tune hierarchical structures and phase evolution, which has significant implication on physico-chemical and mechanical properties.

  12. Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films

    OpenAIRE

    Yujian Sun; Cuihong Zhang; Le Zhou; Hua Fang; Jianhua Huang; Haipeng Ma; Yi Zhang; Jie Yang; Lan-Ying Zhang; Ping Song; Yanzi Gao; Jiumei Xiao; Fasheng Li; Kexuan Li

    2016-01-01

    Polymer-dispersed liquid crystal (PDLC) films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found...

  13. Spin-coating: A new approach for improving dispersion of cellulose nanocrystals and mechanical properties of poly (lactic acid) composites.

    Science.gov (United States)

    Shojaeiarani, Jamileh; Bajwa, Dilpreet S; Stark, Nicole M

    2018-06-15

    This study systematically evaluated the influence of masterbatch preparation techniques, solvent casting and spin-coating methods, on composite properties. Composites were manufactured by combining CNCs masterbatches and PLA resin using twin screw extruder followed by injection molding. Different microscopy techniques were used to investigate the dispersion of CNCs in masterbatches and composites. Thermal, thermomechanical, and mechanical properties of composites were evaluated. Scanning electron microscopy (SEM) images showed superior dispersion of CNCs in spin-coated masterbatches compared to solvent cast masterbatches. At lower CNCs concentrations, both SEM and optical microscope images confirmed more uniform CNCs dispersion in spin-coated composites than solvent cast samples. Degree of crystallinity of PLA exhibited a major enhancement by 147% and 380% in solvent cast and spin-coated composites, respectively. Spin-coated composites with lower CNCs concentration exhibited a noticeable improvement in mechanical properties. However, lower thermal characteristics in spin-coated composites were observed, which could be attributed to the residual solvents in masterbatches. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Properties of Eco-friendly Acrylic Resin/Clay Nanocomposites Prepared by Non-aqueous Dispersion (NAD) Polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeongho; Lee, Minho; Jeon, Hyeon Yeol; Min, Byong Hun; Kim, Jeong Ho [Univ. of Suwon, Hwaseong (Korea, Republic of); Lee, Young Chul [Korea Institute of Industrial Technology, Seoul (Korea, Republic of)

    2016-02-15

    Eco-friendly acrylic resin/clay nanocomposites containing pristine montmorillonite (PM) or modified clays (30B and 25A) were prepared from acrylic and styrenic monomers using non-aqueous dispersion (NAD) polymerization. Effect of nanoclays on physical properties of polymerization product and resulting nanocomposites was investigated. In view of NAD particle stability, addition of nanoclay at the beginning of polymerization is proved to be good. Results of gel fraction, acid value and viscosity of the NAD product showed that nanocomposites containing clay 25A showed better physical properties than the ones with other clays. GPC results exhibit the increase in molecular weight and decrease in polydispersity index for the 25A nanocomposite. Increase in layer distance confirmed from XRD analysis showed good dispersion of 25A in the nanocomposite. Thermal and dynamic mechanical analysis showed that highest glass transition temperature and storage modulus for 25A nanocomposites. These results indicate that 25A nanoclay gives the best properties in the process of non-aqueous dispersion polymerization of acrylic resin/nanoclay nanocomposites.

  15. Analysis of photonic band gap in dispersive properties of tunable three-dimensional photonic crystals doped by magnetized plasma

    International Nuclear Information System (INIS)

    Zhang HaiFeng; Liu Shaobin; Yang Huan; Kong Xiangkun

    2013-01-01

    In this paper, the magnetooptical effects in dispersive properties for two types of three-dimensional magnetized plasma photonic crystals (MPPCs) containing homogeneous dielectric and magnetized plasma with diamond lattices are theoretically investigated for electromagnetic (EM) wave based on plane wave expansion (PWE) method, as incidence EM wave vector is parallel to the external magnetic field. The equations for two types of MPPCs with diamond lattices (dielectric spheres immersed in magnetized plasma background or vice versa) are theoretically deduced. The influences of dielectric constant, plasma collision frequency, filling factor, the external magnetic field, and plasma frequency on the dispersive properties for both types of structures are studied in detail, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that the photonic band gaps (PBGs) for both types of MPPCs can be manipulated by plasma frequency, filling factor, the external magnetic field, and the relative dielectric constant of dielectric, respectively. Especially, the external magnetic field can enlarge the PBG for type-2 structure (plasma spheres immersed in dielectric background). However, the plasma collision frequency has no effect on the dispersive properties of two types of three-dimensional MPPCs. The locations of flatbands regions for both types of structures cannot be tuned by any parameters except for plasma frequency and the external magnetic field. The analytical results may be informative and of technical use to design the MPPCs devices.

  16. Properties of Eco-friendly Acrylic Resin/Clay Nanocomposites Prepared by Non-aqueous Dispersion (NAD) Polymerization

    International Nuclear Information System (INIS)

    Kim, Yeongho; Lee, Minho; Jeon, Hyeon Yeol; Min, Byong Hun; Kim, Jeong Ho; Lee, Young Chul

    2016-01-01

    Eco-friendly acrylic resin/clay nanocomposites containing pristine montmorillonite (PM) or modified clays (30B and 25A) were prepared from acrylic and styrenic monomers using non-aqueous dispersion (NAD) polymerization. Effect of nanoclays on physical properties of polymerization product and resulting nanocomposites was investigated. In view of NAD particle stability, addition of nanoclay at the beginning of polymerization is proved to be good. Results of gel fraction, acid value and viscosity of the NAD product showed that nanocomposites containing clay 25A showed better physical properties than the ones with other clays. GPC results exhibit the increase in molecular weight and decrease in polydispersity index for the 25A nanocomposite. Increase in layer distance confirmed from XRD analysis showed good dispersion of 25A in the nanocomposite. Thermal and dynamic mechanical analysis showed that highest glass transition temperature and storage modulus for 25A nanocomposites. These results indicate that 25A nanoclay gives the best properties in the process of non-aqueous dispersion polymerization of acrylic resin/nanoclay nanocomposites

  17. Structural analysis and unique molecular recognition properties of a Bauhinia forficata lectin that inhibits cancer cell growth.

    Science.gov (United States)

    Lubkowski, Jacek; Durbin, Sarah V; Silva, Mariana C C; Farnsworth, David; Gildersleeve, Jeffrey C; Oliva, Maria Luiza V; Wlodawer, Alexander

    2017-02-01

    Lectins have been used at length for basic research and clinical applications. New insights into the molecular recognition properties enhance our basic understanding of carbohydrate-protein interactions and aid in the design/development of new lectins. In this study, we used a combination of cell-based assays, glycan microarrays, and X-ray crystallography to evaluate the structure and function of the recombinant Bauhinia forficata lectin (BfL). The lectin was shown to be cytostatic for several cancer cell lines included in the NCI-60 panel; in particular, it inhibited growth of melanoma cancer cells (LOX IMVI) by over 95%. BfL is dimeric in solution and highly specific for binding of oligosaccharides and glycopeptides with terminal N-acetylgalactosamine (GalNAc). BfL was found to have especially strong binding (apparent K d  = 0.5-1.0 nm) to the tumor-associated Tn antigen. High-resolution crystal structures were determined for the ligand-free lectin, as well as for its complexes with three Tn glycopeptides, globotetraose, and the blood group A antigen. Extensive analysis of the eight crystal structures and comparison to structures of related lectins revealed several unique features of GalNAc recognition. Of special note, the carboxylate group of Glu126, lining the glycan-binding pocket, forms H-bonds with both the N-acetyl of GalNAc and the peptide amido group of Tn antigens. Stabilization provided by Glu126 is described here for the first time for any GalNAc-specific lectin. Taken together, the results provide new insights into the molecular recognition of carbohydrates and provide a structural understanding that will enable rational engineering of BfL for a variety of applications. Structural data are available in the PDB under the accession numbers 5T50, 5T52, 5T55, 5T54, 5T5L, 5T5J, 5T5P, and 5T5O. © 2016 Federation of European Biochemical Societies.

  18. A noncovalent functionalization approach to improve the dispersibility and properties of polymer/MoS2 composites

    International Nuclear Information System (INIS)

    Zhou, Keqing; Liu, Jiajia; Wen, Panyue; Hu, Yuan; Gui, Zhou

    2014-01-01

    Highlights: • In this work, we have reported a convenient method to modify molybdenum disulfide (MoS 2 ) nanosheets. • The organic modified MoS 2 nanosheets dispersed well in organic solvents and aqueous solution simultaneously. • This well dispersion can be used to prepare polymer/MoS 2 nanocomposites with an exfoliation structure by a simple solvent mixing method. • The organic modified MoS 2 nanosheets show promising reinforcing efficiency in the thermal stability, fire resistance and thermomechanical properties of the polymer/MoS 2 nanocomposites. - Abstract: In the evolution of high performance layered inorganic compounds/polymer nanocomposites, homogeneous dispersion of inorganic nanoplatelets in the polymer matrix and exact interface control are difficult to achieve due to the potent interlayer cohesive energy and surface inactiveness of the nanocomposites. Pristine MoS 2 exhibits poor solubility in both water and organic solvents. Herein, it is necessary to modify the surface of molybdenum disulfide (MoS 2 ) nanosheets with functional groups, in order to enhance its dispersity and compatibility in various solvents and polymer matrices. In this paper, we have reported a convenient method to modify MoS 2 nanosheets with common cationic surfactant and polymer, these organic modified MoS 2 nanosheets dispersed well in organic solvents and aqueous solution simultaneously. This well dispersion can be used to prepare polymer/MoS 2 nanocomposites by a simple solvent mixing method which was found to display an exfoliation structure of MoS 2 nanosheets and improve the performances of the polymer nanocomposites. With the addition of 3 wt% CTAB-MoS 2 , T 10% and T 50% of the samples are increased by 60 °C, respectively. Moreover, the storage modulus of sample PS/3% CTAB-MoS 2 had 84% increment compared with that of pure PS at 30 °C

  19. Synthesis and properties of highly dispersed ionic silica-poly(ethylene oxide) nanohybrids.

    KAUST Repository

    Fernandes, Nikhil J

    2013-02-04

    We report an ionic hybrid based on silica nanoparticles as the anion and amine-terminated poly(ethylene oxide) (PEO) as a cation. The charge on the nanoparticle anion is carried by the surface hydroxyls. SAXS and TEM reveal an exceptional degree of dispersion of the silica in the polymer and high degree of order in both thin film and bulk forms. In addition to better dispersion, the ionic hybrid shows improved flow characteristics compared to silica/PEO mixtures in which the ionic interactions are absent.

  20. Synthesis and properties of highly dispersed ionic silica-poly(ethylene oxide) nanohybrids.

    KAUST Repository

    Fernandes, Nikhil J; Akbarzadeh, Johanna; Peterlik, Herwig; Giannelis, Emmanuel P

    2013-01-01

    We report an ionic hybrid based on silica nanoparticles as the anion and amine-terminated poly(ethylene oxide) (PEO) as a cation. The charge on the nanoparticle anion is carried by the surface hydroxyls. SAXS and TEM reveal an exceptional degree of dispersion of the silica in the polymer and high degree of order in both thin film and bulk forms. In addition to better dispersion, the ionic hybrid shows improved flow characteristics compared to silica/PEO mixtures in which the ionic interactions are absent.

  1. Computational sensitivity study of spray dispersion and mixing on the fuel properties in a gas turbine combustor

    Energy Technology Data Exchange (ETDEWEB)

    Grosshans, Holger; Szász, Robert-Zoltán [Division of Fluid Mechanics, Lund University (Sweden); Cao, Le [Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing (China); Fuchs, Laszlo, E-mail: holger.grosshans@uclouvain.be [Department of Mechanics, KTH, Stockholm (Sweden)

    2017-04-15

    A swirl stabilized gas turbine burner has been simulated in order to assess the effects of the fuel properties on spray dispersion and fuel–air mixing. The properties under consideration include fuel surface tension, viscosity and density. The turbulence of the gas phase is modeled applying the methodology of large eddy simulation whereas the dispersed liquid phase is described by Lagrangian particle tracking. The exchange of mass, momentum and energy between the two phases is accounted for by two-way coupling. Bag and stripping breakup regimes are considered for secondary droplet breakup, using the Reitz–Diwakar and the Taylor analogy breakup models. Moreover, a model for droplet evaporation is included. The results reveal a high sensitivity of the spray structure to variations of all investigated parameters. In particular, a decrease in the surface tension or the fuel viscosity, or an increase in the fuel density, lead to less stable liquid structures. As a consequence, smaller droplets are generated and the overall spray surface area increases, leading to faster evaporation and mixing. Furthermore, with the trajectories of the small droplets being strongly influenced by aerodynamic forces (and less by their own inertia), the spray is more affected by the turbulent structures of the gaseous phase and the spray dispersion is enhanced. (paper)

  2. A study of the physical properties of lamellar liquid-crystalline dispersions

    NARCIS (Netherlands)

    Pas, Johannes Cornelis van de

    1993-01-01

    Important questions addressed in this thesis are (i) which are the factors governing the physical stability of these dispersions and (ii) what is the relation between the chemical composition of the surfactant and the physical stability of these systems as a function of electrolyte type and

  3. Photonic crystal waveguides with semi-slow light and tailored dispersion properties

    DEFF Research Database (Denmark)

    Frandsen, Lars Hagedorn; Lavrinenko, Andrei; Fage-Pedersen, Jacob

    2006-01-01

    waveguide with either vanishing, positive, or negative group velocity dispersion and semi-slow light. We realize experimentally a silicon-on-insulator photonic crystal waveguide having nearly constant group velocity [similar to]c$-0$//34 in an 11-nm bandwidth below the silica-line. $CPY@2006 Optical Society...

  4. Synthesis of water dispersible polyaniline/poly(styrenesulfonic acid) modified graphene composite and its electrochemical properties

    International Nuclear Information System (INIS)

    Luo, Jing; Jiang, Sisi; Liu, Ren; Zhang, Yongjie; Liu, Xiaoya

    2013-01-01

    A novel water-dispersible polyaniline (PANI)/graphene composite was prepared by the in situ polymerization of aniline on the surface of poly(styrenesulfonic acid) (PSS) coated graphene nanosheets (PSS-GR). The characterization of atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy confirmed the successful synthesis of PANI/PSS-GR composites and strong interaction between PANI and PSS-GR. The as-synthesized PANI/PSS-GR composite is readily dispersible in water and forms a homogeneous aqueous dispersion which is stable for more than one month. More interestingly, PSS-GR can dope PANI effectively and shift its electroactivity to a neutral or even alkaline environment, making them promising candidates for biological application. In addition, the PANI/PSS-GR composite shows improved electrical conductivity and electrochemical stability compared to the neat polyaniline. Furthermore, the potential use of this composite for detection of ascorbic acid (AA) was investigated. A low detection limit of 5 × 10 −6 M and a linear detection range between 1 × 10 −4 M and 1 × 10 −3 M was attained, indicating the high electrocatalytic ability of this composite. Anticipatedly, the synthesized composite will find promising applications as a novel electrode material in sensors and other devices in virtue of their outstanding characteristics of water-dispersibility, good cycle stability, electroactivity in neutral solution and excellent electrocatalytic ability

  5. Polyaniline–maghemite based dispersion: electrical, magnetic properties and their cytotoxicity

    Czech Academy of Sciences Publication Activity Database

    Bober, Patrycja; Zasońska, Beata Anna; Humpolíček, P.; Kuceková, Z.; Varga, M.; Horák, Daniel; Babayan, V.; Kazantseva, N.; Prokeš, J.; Stejskal, Jaroslav

    2016-01-01

    Roč. 214, April (2016), s. 23-29 ISSN 0379-6779 R&D Projects: GA ČR(CZ) GP14-05568P; GA MŠk(CZ) LH14318 Institutional support: RVO:61389013 Keywords : conducting polymer * magnetic dispersion * polyaniline Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.435, year: 2016

  6. Dispersion Forces

    CERN Document Server

    Buhmann, Stefan Yoshi

    2012-01-01

    In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of advanced aspects and scenarios. Macroscopic quantum electrodynamics is shown to provide a powerful framework for dispersion forces which allows for discussing general properties like their non-additivity and the relation between microscopic and macroscopic interactions. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. Starting with a brief recapitulation of volume I, this volume II deals especially with bodies of irregular shapes, universal scaling laws, dynamical forces on excited atoms, enhanced forces in cavity quantum electrodynamics, non-equilibrium forces in thermal environments and quantum friction. The book gives both the specialist and those new to the field a thorough overview over recent results in the field. It provides a toolbox for studying dispersion forces in various contex...

  7. Nanocomposites based on epoxy resin and montmorillonite: effect of clay percent and dispersion state on thermomechanical properties

    International Nuclear Information System (INIS)

    Zaioncz, Soraia; Soares, Bluma G.

    2009-01-01

    Nanocomposites of epoxy resin modified with PMMA and montmorillonite organophilic were synthesized with clay content equal to 0.1, 1, 2.5, 5 and 7 (wt %). Dispersion state and the nano structure of materials has been investigated using small angle X-ray scattering (SAXS). The nanocomposites containing 0.1 (wt %) of clay showed an exfoliated morphology, while the nanocomposites with higher clay content (1 to 7 wt %) show that the dispersion state is less uniform and that large aggregates coexist with tactoids stacks of two or three platelets. The nano structure of materials was correlated with its thermomechanical properties obtained by DMTA. The results showed an increase in Tg of the materials to clay content of up to 5 wt % and an increase in the storage modulus for the epoxy matrix. (author)

  8. Enhanced Mechanical Properties of MgZnCa Bulk Metallic Glass Composites with Ti-Particle Dispersion

    Directory of Open Access Journals (Sweden)

    Pei Chun Wong

    2016-05-01

    Full Text Available Rod samples of Mg60Zn35Ca5 bulk metallic glass composites (BMGCs dispersed with Ti particles have been successfully fabricated via injection casting. The glass forming ability (GFA and the mechanical properties of these Mg-based BMGCs have been systematically investigated as a function of the volume fraction (Vf of Ti particles. The results showed that the compressive ductility increased with Vf. The mechanical performance of these BMGCs, with up to 5.4% compressive failure strain and 1187 MPa fracture strength at room temperature, can be obtained for the Mg-based BMGCs with 50 vol % Ti particles, suggesting that these dispersed Ti particles can absorb the energy of the crack propagations and can induce branches of the primary shear band into multiple secondary shear bands. It follows that further propagation of the shear band is blocked, enhancing the overall plasticity.

  9. Gum tragacanth dispersions: Particle size and rheological properties affected by high-shear homogenization.

    Science.gov (United States)

    Farzi, Mina; Yarmand, Mohammad Saeed; Safari, Mohammad; Emam-Djomeh, Zahra; Mohammadifar, Mohammad Amin

    2015-08-01

    The effect of high-shear homogenization on the rheological and particle size characteristics of three species of gum tragacanth (GT) was detected. Dispersions were subjected to 0-20 min treatment. Static light scattering techniques and rheological tests were used to study the effect of treatment. The results showed that the process caused a decrease in particle size parameters for all three species, but interestingly, the apparent viscosities increased. The highest increase of apparent viscosity was found for solutions containing Astragalus gossypinus, which possessed the highest insoluble fraction. The viscoelastic behaviors of dispersions were also significantly influenced by the process. Homogenization caused an increase in both G' and G″, in all three species. The alterations seem to be highly dependent on GT species and structure. The results could be of high importance in the industry, since the process will lead to textural modifications of food products containing GT. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Dispersion properties of Kolakoski-cladding hollow-core nanophotonic Bragg waveguide

    Directory of Open Access Journals (Sweden)

    Fesenko Volodymyr I.

    2016-09-01

    Full Text Available A comprehensive analysis of guided modes of a novel type of a planar Bragg reflection waveguide that consists of a low refractive index guiding layer sandwiched between two finite aperiodic mirrors is presented. The layers in the mirrors are aperiodically arranged according to the Kolakoski substitution rule. In such a waveguide, light is confined inside the core by Bragg reflection, while dispersion characteristics of guided modes strongly depend on aperiodicity of the cladding. Using the transfer matrix formalism bandgap conditions, dispersion characteristics and mode profiles of the guided modes of such a waveguide are studied on the GaAs/AlAs and Si/SiO2 epitaxial platforms, which are compatible with hybrid and heteroepitaxial frameworks of silicon photonics.

  11. Properties of Mechanically Alloyed W-Ti Materials with Dual Phase Particle Dispersion

    Czech Academy of Sciences Publication Activity Database

    Lukáč, František; Vilémová, Monika; Nevrlá, Barbara; Klečka, Jakub; Chráska, Tomáš; Molnárová, O.

    2017-01-01

    Roč. 7, č. 1 (2017), č. článku 3. ISSN 2075-4701 R&D Projects: GA ČR(CZ) GA15-15609S Institutional support: RVO:61389021 Keywords : tungsten-titanium alloys * mechanical alloying * particle dispersion * pulsed electric current sintering * thermal conductivity * bending strength Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 1.984, year: 2016

  12. Dispersion Properties of Photonic Crystals and Silicon Nanostructures Investigated by Fourier-Space Imaging

    OpenAIRE

    Jágerská, Jana

    2011-01-01

    State-of-the-art nanophotonic devices based on semiconductor technology use total internal reflection or the photonic bandgap effect to reduce the waveguide core dimensions down to hundreds of nanometers, ensuring strong optical confinement within the scale of the wavelength. Within the framework of this thesis, we investigate the light propagation in such devices by direct experimental reconstruction of their dispersion relation ω (k), where ω ...

  13. Biological properties of printable polyaniline and polyaniline-silver colloidal dispersions stabilized by gelatin

    Czech Academy of Sciences Publication Activity Database

    Bober, Patrycja; Humpolíček, P.; Syrový, T.; Capáková, Z.; Syrová, L.; Hromádková, Jiřina; Stejskal, Jaroslav

    2017-01-01

    Roč. 232, October (2017), s. 52-59 ISSN 0379-6779 R&D Projects: GA ČR(CZ) GP14-05568P; GA ČR(CZ) GA17-05095S; GA TA ČR(CZ) TE01020022 Institutional support: RVO:61389013 Keywords : conducting polymer * colloidal dispersion * hybrid composite Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 2.435, year: 2016

  14. Radiometric and signal-to-noise ratio properties of multiplex dispersive spectrometry

    International Nuclear Information System (INIS)

    Barducci, Alessandro; Guzzi, Donatella; Lastri, Cinzia; Nardino, Vanni; Marcoionni, Paolo; Pippi, Ivan

    2010-01-01

    Recent theoretical investigations have shown important radiometric disadvantages of interferential multiplexing in Fourier transform spectrometry that apparently can be applied even to coded aperture spectrometers. We have reexamined the methods of noninterferential multiplexing in order to assess their signal-to-noise ratio (SNR) performance, relying on a theoretical modeling of the multiplexed signals. We are able to show that quite similar SNR and radiometric disadvantages affect multiplex dispersive spectrometry. The effect of noise on spectral estimations is discussed.

  15. Improving Dispersion and Barrier Properties of Polyketone/Graphene Nanoplatelet Composites via Noncovalent Functionalization Using Aminopyrene.

    Science.gov (United States)

    Cho, Jaehyun; Jeon, Ikseong; Kim, Seong Yun; Lim, Soonho; Jho, Jae Young

    2017-08-23

    A series of polyketone (PK) nanocomposite films with varying content of noncovalently functionalized graphene nanoplatelet with 1-aminopyrene (GNP/APy) is prepared by solution blending with a solvent of hexafluoro-2-propanol. GNP/APy, prepared by a facile method, can effectively induce specific interaction such as hydrogen bonding between the amine functional group of GNP/APy and the carbonyl functional group of the PK matrix. With comparison of GNP and GNP/Py as reference materials, intensive investigation on filler-matrix interaction is achieved. In addition, the dispersion state of the functionalized GNP (f-GNPs; GNP/Py and GNP/APy) in the PK matrix is analyzed by three-dimensional nondestructive X-ray microcomputed tomography, and the increased dispersion state of those fillers results in significant improvement in the water vapor transmission rate (WVTR). The enhancement in WVTR of the PK/GNP/APy nanocomposite film at 1 wt % loading of filler leads to a barrier performance approximately 2 times larger compared to that of PK/GNP nanocomposite film and an approximately 92% reduction in WVTR compared to the case of pristine PK film. We expect that this facile method of graphene functionalization to enhance graphene dispersibility as well as interfacial interaction with the polymer matrix will be widely utilized to expand the potential of graphene materials to barrier film applications.

  16. Microstructure and tensile properties of yttrium nitride dispersion-strengthened 14Cr–3W ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Liqing [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); School of Mechanical and Mining Engineering, University of Queensland, Brisbane 4067, QLD (Australia); Liu, Zuming, E-mail: lzm@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Chen, Shiqi; Guo, Yang [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2015-12-15

    Highlights: • Innovative nano yttrium nitride dispersion strengthened steels were fabricated. • Higher content of additives accelerate the steel-ceramic powder milling process more. • Steel with high content (3%) of YN dispersoids can obtain good performance at 500 °C. - Abstract: 14Cr–3W ferritic steel powders were mechanically milled with microscale yttrium nitride (YN) particles to fabricate particle dispersion-strengthened ferritic steels. After hot consolidation and annealing, the steel matrix was homogeneously dispersed with nano-scale YN particles. The steel containing 0.3 wt.% YN particles exhibited a yield strength of 1445 MPa at room temperature. Its total elongation was 10.3%, and the fracture surface exhibited mixed ductile and quasi-cleavage fracture morphologies. The steel with a much higher content of YN particles (3 wt.%) in its matrix was much stronger (1652 MPa) at room temperature at the cost of ductility. In particular, it exhibited a high yield strength (1350 MPa) with applicable ductility (total elongation > 10%) at 500 °C. This study has developed a new kind of reinforcement particle to fabricate high-performance ferritic steels.

  17. Nanoionics phenomenon in proton-conducting oxide: Effect of dispersion of nanosize platinum particles on electrical conduction properties

    Directory of Open Access Journals (Sweden)

    Hiroshige Matsumoto et al

    2007-01-01

    Full Text Available High-temperature proton conductors are oxides in which low-valence cations are doped as electron acceptors; the incorporation of water molecules into the oxides results in the formation of protonic defects that act as charge carriers. Since the protons thus formed are in equilibrium with other electronic defects, electrons and holes, the oxides possibly have different proton-conduction properties at and near boundaries when they are in contact with another phase. In this paper, we present our recent experimental observation of a marked change in the electrical properties of a proton conductor upon the dispersal of fine platinum particles in the oxide. First, the material shows extremely low electrical conductivity in comparison with the original proton-conducting perovskite. Second, there was a threshold amount of platinum at which such a drop in conductivity occurred. A percolation model is employed to explain these experimental results; the fine platinum particles dispersed in the proton-conducting oxide wears highly resistive skin that is formed due to shifts in defect equilibriums, which prevents ionic/electronic conduction. The experiments suggest that the ion-conducting properties of oxides can be varied by introducing interfaces at a certain density; nanoionics is a key to yielding enhanced and/or controlled ionic conduction in solids.

  18. Development of accurate UWB dielectric properties dispersion at CST simulation tool for modeling microwave interactions with numerical breast phantoms

    International Nuclear Information System (INIS)

    Maher, A.; Quboa, K. M.

    2011-01-01

    In this paper, a reformulation for the recently published dielectric properties dispersion models of the breast tissues is carried out to be used by CST simulation tool. The reformulation includes tabulation of the real and imaginary parts versus frequency on ultra-wideband (UWB) for these models by MATLAB programs. The tables are imported and fitted by CST simulation tool to second or first order general equations. The results have shown good agreement between the original and the imported data. The MATLAB programs written in MATLAB code are included in the appendix.

  19. Additively manufactured metallic porous biomaterials based on minimal surfaces: A unique combination of topological, mechanical, and mass transport properties.

    Science.gov (United States)

    Bobbert, F S L; Lietaert, K; Eftekhari, A A; Pouran, B; Ahmadi, S M; Weinans, H; Zadpoor, A A

    2017-04-15

    Porous biomaterials that simultaneously mimic the topological, mechanical, and mass transport properties of bone are in great demand but are rarely found in the literature. In this study, we rationally designed and additively manufactured (AM) porous metallic biomaterials based on four different types of triply periodic minimal surfaces (TPMS) that mimic the properties of bone to an unprecedented level of multi-physics detail. Sixteen different types of porous biomaterials were rationally designed and fabricated using selective laser melting (SLM) from a titanium alloy (Ti-6Al-4V). The topology, quasi-static mechanical properties, fatigue resistance, and permeability of the developed biomaterials were then characterized. In terms of topology, the biomaterials resembled the morphological properties of trabecular bone including mean surface curvatures close to zero. The biomaterials showed a favorable but rare combination of relatively low elastic properties in the range of those observed for trabecular bone and high yield strengths exceeding those reported for cortical bone. This combination allows for simultaneously avoiding stress shielding, while providing ample mechanical support for bone tissue regeneration and osseointegration. Furthermore, as opposed to other AM porous biomaterials developed to date for which the fatigue endurance limit has been found to be ≈20% of their yield (or plateau) stress, some of the biomaterials developed in the current study show extremely high fatigue resistance with endurance limits up to 60% of their yield stress. It was also found that the permeability values measured for the developed biomaterials were in the range of values reported for trabecular bone. In summary, the developed porous metallic biomaterials based on TPMS mimic the topological, mechanical, and physical properties of trabecular bone to a great degree. These properties make them potential candidates to be applied as parts of orthopedic implants and/or as bone

  20. A noncovalent functionalization approach to improve the dispersibility and properties of polymer/MoS{sub 2} composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Keqing; Liu, Jiajia; Wen, Panyue; Hu, Yuan, E-mail: yuanhu@ustc.edu.cn; Gui, Zhou, E-mail: zgui@ustc.edu.cn

    2014-10-15

    Highlights: • In this work, we have reported a convenient method to modify molybdenum disulfide (MoS{sub 2}) nanosheets. • The organic modified MoS{sub 2} nanosheets dispersed well in organic solvents and aqueous solution simultaneously. • This well dispersion can be used to prepare polymer/MoS{sub 2} nanocomposites with an exfoliation structure by a simple solvent mixing method. • The organic modified MoS{sub 2} nanosheets show promising reinforcing efficiency in the thermal stability, fire resistance and thermomechanical properties of the polymer/MoS{sub 2} nanocomposites. - Abstract: In the evolution of high performance layered inorganic compounds/polymer nanocomposites, homogeneous dispersion of inorganic nanoplatelets in the polymer matrix and exact interface control are difficult to achieve due to the potent interlayer cohesive energy and surface inactiveness of the nanocomposites. Pristine MoS{sub 2} exhibits poor solubility in both water and organic solvents. Herein, it is necessary to modify the surface of molybdenum disulfide (MoS{sub 2}) nanosheets with functional groups, in order to enhance its dispersity and compatibility in various solvents and polymer matrices. In this paper, we have reported a convenient method to modify MoS{sub 2} nanosheets with common cationic surfactant and polymer, these organic modified MoS{sub 2} nanosheets dispersed well in organic solvents and aqueous solution simultaneously. This well dispersion can be used to prepare polymer/MoS{sub 2} nanocomposites by a simple solvent mixing method which was found to display an exfoliation structure of MoS{sub 2} nanosheets and improve the performances of the polymer nanocomposites. With the addition of 3 wt% CTAB-MoS{sub 2}, T{sub 10%} and T{sub 50%} of the samples are increased by 60 °C, respectively. Moreover, the storage modulus of sample PS/3% CTAB-MoS{sub 2} had 84% increment compared with that of pure PS at 30 °C.

  1. Design and Manufacture an Ultrasonic Dispersion System with Automatic Frequency Adjusting Property

    Directory of Open Access Journals (Sweden)

    Herlina ABDUL RAHIM

    2011-03-01

    Full Text Available This paper a novel ultrasonic dispersion system for the cleaning application or dispersing of particles which are mixed in liquid has been proposed. The frequency band of designed system is 30 kHz so that the frequency of ultrasonic wave sweeps from 30 kHz to 60 kHz with 100 Hz steps. One of the superiority of manufactured system in compare with the other similar systems which are available in markets is that this system can transfer the maximum and optimum energy of ultrasonic wave inside the liquid tank with the high efficiency in the whole of the usage time of the system. The used ultrasonic transducers in this system as the generator of ultrasonic wave is the type of air coupled ceramic ultrasonic piezoelectric with the nominal maximum power 50 Watt. The frequency characteristic of applied piezoelectric is that it produces the maximum amplitude of ultrasonic wave on the resonance frequency, so this system is designed to work on resonance frequency of piezoelectric, continuously. This is done by the use of control system which is consisted of two major parts, sensing part and controlling part. The manufactured ultrasonic dispersion system is consisted of 9 piezoelectrics so that it can produce 450 watt ultrasonic energy, totally. The main purpose of this project is to produce a safety system especially for fatigue car driver so as to prevent from accidents. The statistic on road fatality shows that human error constitute of 64.84 % road accidents fatality and 17.4 % due to technical factors. These systems encompassed the approach of hand pressure applied on the steering wheel. The steering will be installed with pressure sensors. At the same time these sensors can be used to measure gripping force while driving.

  2. INVESTIGATION OF THE PHARMACO-TECHNOLOGICAL PROPERTIES OF SOLID DISPERSIONS OF THIOCTIC ACID, OBTAINED BY MICRONIZATION

    Directory of Open Access Journals (Sweden)

    Kovalevska, I. V.

    2018-04-01

    Full Text Available Introduction. Thioctic acid is used in the treatment of diseases that are characterized by lack of mitochondrial activity, which is responsible for the formation of free radicals. Widespread use of thioctic acid is due to the chemical structure. The thioctic acid exhibits biological activity in both hydrophilic and hydrophobic environments. Thioctic acid is an enzyme cofactor and a powerful antioxidant, it regulates the transcription of numerous genes, participates in regulation of glucose and lipid metabolism, increases insulin sensitivity, and forms complexes with heavy metals. Thioctic acid has a high pharmacological potential, which is confirmed by the evidence base of clinical trials. An analysis of the literature on the oral use of thioctic acid indicates that solid dosage forms can be used for long-term therapy. This route of administration is limited by factors such as reduced solubility in acidic environments and enzymatic degradation. For this reason, the search for various compositions of auxiliary substances and methods of obtaining drugs is an urgent task of pharmaceutical technology. Material & methods. Objects of study were solid dispersions of thioctic acid (SDTA on the basis of cellulose derivatives: microcrystalline (MCC, HPMC (hydroxypropyl methylcellulose and polyvinylpyrrolidone (PVP as compared to thioctic acid (TA. The samples were made by solid phase method using micronization in a laboratory shredder at a ratio of 1: 1. Pharmacological and technological parameters were determined according to generally accepted methods. Results & discussion. In appearance the resulting mixtures had lemon color, without inclusions and the formation of conglomerates, with homogeneous sized particles According to the pharmaco-technological studies, the samples do not have a satisfactory flowability. The values of the Carr index and the ratio of Hausner make it possible to conclude that there is a large force of cohesion between the

  3. Low-loss photonic crystal fibers for data transmission and their dispersion properties

    DEFF Research Database (Denmark)

    Nielsen, Martin Dybendal; Jacobsen, Christian; Mortensen, Niels Asger

    2004-01-01

    We report on a single-mode photonic crystal fiber with attenuation and effective area at 1550 nm of 0.48 dB/km and 130 µm2, respectively. This is, to our knowledge, the lowest loss reported for a PCF not made from VAD prepared silica and at the same time the largest effective area for a low......-loss (data transmission and show for the first time, both numerically and experimentally, how the group velocity dispersion is related to the mode field diameter....

  4. A New Star-shaped Carbazole Derivative with Polyhedral Oligomeric Silsesquioxane Core: Crystal Structure and Unique Photoluminescence Property.

    Science.gov (United States)

    Xu, Zixuan; Yu, Tianzhi; Zhao, Yuling; Zhang, Hui; Zhao, Guoyun; Li, Jianfeng; Chai, Lanqin

    2016-01-01

    A new inorganic–organic hybrid material based on polyhedral oligomeric silsesquioxane (POSS) capped with carbazolyl substituents, octakis[3-(carbazol-9-yl)propyldimethylsiloxy]-silsesquioxane (POSS-8Cz), was successfully synthesized and characterized. The X-ray crystal structure of POSS-8Cz were described. The photophysical properties of POSS-8Cz were investigated by using UV–vis,photoluminescence spectroscopic analysis. The hybrid material exhibits blue emission in the solution and the solid film.The morphology and thermal stablity properties were measured by X-ray diffraction (XRD) and TG-DTA analysis.

  5. Nanocrystalline cellulose-dispersed AKD emulsion for enhancing the mechanical and multiple barrier properties of surface-sized paper.

    Science.gov (United States)

    Yang, Luming; Lu, Sheng; Li, Juanjuan; Zhang, Fengshan; Cha, Ruitao

    2016-01-20

    In this study, we employed nanocrystalline cellulose (NCC) as an efficient dispersant to perpare alkyl ketene dimer (AKD) emulsion. The particle size and zeta potential of AKD/NCC emulsion were measured, which were approximately 5 μm and -50 mV, respectively. The surface-sized paper possessed multiple barriers properties. The air permeability of surface-sized paper was 0.29 μm/Pas and the sizing degree reached 42 s when the amount of sizing was 12.58 g/m(2) with a 96.83% decrease and a 40.00%, increase, respectively. Furthermore, the mechanical properties were optimal when the amount of sizing was about 8 g/m(2). AKD/NCC emulsion acted as a good reinforcing agent in surface-sized paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Nanoparticles dispersion in processing functionalised PP/TiO2 nanocomposites: distribution and properties

    International Nuclear Information System (INIS)

    El-Dessouky, Hassan M.; Lawrence, Carl A.

    2011-01-01

    Future innovations in textiles and fibrous materials are likely to demand fibres with enhanced multifunctionality. The fibres can be functionalized by dispersing nanoadditives into the polymer during melt compounding/spinning. TiO 2 nanoparticles have the potential to improve UV resistance, antistatic, as well as impart self-cleaning by photocatalysis and thereby de-odour and antimicrobial effects. In this study, a micro-lab twin-screw extruder was used to produce samples of polypropylene (PP) nanocomposite monofilaments, doped with nano titanium oxide (TiO 2 )/manganese oxide (MnO) compound having size ranging from 60 to 200 nm. As a control sample, PP filaments without additives were also extruded. Three samples were produced containing different concentrations (wt%) of the TiO 2 compound, i.e. 0.95, 1.24 and 1.79%. Nano metal-oxide distribution in the as-spun and drawn nanocomposite filaments was analysed. Although, there are small clusters of the nanoparticles, the characterizing techniques showed good dispersion and distribution of the modified TiO 2 along and across the processed filaments. From UV spectroscopy and TGA, a significant enhancement of polypropylene UV protection and thermal stability were observed: PP with higher percentage of TiO 2 absorbed UV wavelength of 387 nm and thermally decomposed at 320.16 °C accompanied by 95% weight loss.

  7. Nacre-Templated Synthesis of Highly Dispersible Carbon Nanomeshes for Layered Membranes with High-Flux Filtration and Sensing Properties.

    Science.gov (United States)

    Kong, Meng; Li, Mingjie; Shang, Ruoxu; Wu, Jingyu; Yan, Peisong; Xu, Dongmei; Li, Chaoxu

    2018-01-24

    Marine shells not only represent a rapidly accumulating type of fishery wastes but also offer a unique sort of hybrid nanomaterials produced greenly and massively in nature. The elaborate "brick and mortar" structures of nacre enabled the synthesis of carbon nanomeshes with <1 nm thickness, hierarchical porosity, and high specific surface area through pyrolysis, in which two-dimensional (2D) organic layers served as the carbonaceous precursor and aragonite platelets as the hard template. Mineral bridges within 2D organic layers templated the formation of mesh pores of 20-70 nm. In contrast to other hydrophobic carbon nanomaterials, these carbon nanomeshes showed super dispersibility in diverse solvents and thus processability for membranes through filtration, patterning, spray-coating, and ink-writing. The carbon membranes with layered structures were capable of serving not only for high-flux filtration and continuous flow absorption but also for electrochemical and strain sensing with high sensitivity. Thus, utilization of marine shells, on one hand, relieves the environmental concern of shellfish waste, on the other hand, offers a facile, green, low-cost, and massive approach to synthesize unique carbon nanomeshes alternative to graphene nanomeshes and applicable in environmental adsorption, filtration, wearable sensors, and flexible microelectronics.

  8. Effect of dispersion capability of organoclay on cellular structure and physical properties of PMMA/clay nanocomposite foams

    International Nuclear Information System (INIS)

    Yeh, Jui-Ming; Chang, Kung-Chin; Peng, Chih-Wei; Lai, Mei-Chun; Hung, Chih-Bing; Hsu, Sheng-Chieh; Hwang, Shyh-Shin; Lin, Hong-Ru

    2009-01-01

    In this study, PMMA/clay nanocomposite (PCN) materials with two kinds of organoclay were prepared via in situ bulk polymerization. The as-prepared PCN materials were then characterized by Fourier transformation infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXRD) and transmission electron microscopy (TEM). WAXRD and TEM analysis revealed that combination of both intercalated and exfoliated nanocomposites was formed and the silicate layers of the clay were uniformly dispersed at a nanometer scale in PMMA matrix. The molecular weights of PMMA extracted from PCN materials and bulk PMMA were determined by gel permeation chromatography (GPC) with THF used as the eluant. The PCN materials were used to produce foams by a batch process in an autoclave using nitrogen as foaming agent. The cellular structure analysis of foams was examined by SEM. The effect of dispersion capability of organoclay on the dielectric and thermal transport properties of PCN materials and foams and mechanical properties of PCN foams were investigated by LCR meter, transient plane source (TPS) technique and dynamic mechanical analysis (DMA), respectively.

  9. Bridging adhesion and barrier properties with functional dispersions : towards waterborne anti-corrosion coatings

    NARCIS (Netherlands)

    Soer, W.J.

    2008-01-01

    The successful preparation of waterborne anti-corrosion coatings based on maleic anhydride containing copolymers is described in this thesis. To obtain good anticorrosion coatings, three different properties should be present in a coating system; they should display good mechanical properties, good

  10. Additively manufactured metallic porous biomaterials based on minimal surfaces : A unique combination of topological, mechanical, and mass transport properties

    NARCIS (Netherlands)

    Bobbert, F S L; Lietaert, K; Eftekhari, A A; Pouran, B; Ahmadi, S M; Weinans, H; Zadpoor, A A

    2017-01-01

    Porous biomaterials that simultaneously mimic the topological, mechanical, and mass transport properties of bone are in great demand but are rarely found in the literature. In this study, we rationally designed and additively manufactured (AM) porous metallic biomaterials based on four different

  11. Unique Piezoelectric Properties of the Monoclinic Phase in Pb (Zr ,Ti )O3 Ceramics: Large Lattice Strain and Negligible Domain Switching

    Science.gov (United States)

    Fan, Longlong; Chen, Jun; Ren, Yang; Pan, Zhao; Zhang, Linxing; Xing, Xianran

    2016-01-01

    The origin of the excellent piezoelectric properties at the morphotropic phase boundary is generally attributed to the existence of a monoclinic phase in various piezoelectric systems. However, there exist no experimental studies that reveal the role of the monoclinic phase in the piezoelectric behavior in phase-pure ceramics. In this work, a single monoclinic phase has been identified in Pb (Zr ,Ti )O3 ceramics at room temperature by in situ high-energy synchrotron x-ray diffraction, and its response to electric field has been characterized for the first time. Unique piezoelectric properties of the monoclinic phase in terms of large intrinsic lattice strain and negligible domain switching have been observed. The extensional strain constant d33 and the transverse strain constant d31 are calculated to be 520 and -200 pm /V , respectively. These large piezoelectric coefficients are mainly due to the large intrinsic lattice strain, with very little extrinsic contribution from domain switching. The unique properties of the monoclinic phase provide new insights into the mechanisms responsible for the piezoelectric properties at the morphotropic phase boundary.

  12. Unique Piezoelectric Properties of the Monoclinic Phase in Pb(Zr,Ti)O_{3} Ceramics: Large Lattice Strain and Negligible Domain Switching.

    Science.gov (United States)

    Fan, Longlong; Chen, Jun; Ren, Yang; Pan, Zhao; Zhang, Linxing; Xing, Xianran

    2016-01-15

    The origin of the excellent piezoelectric properties at the morphotropic phase boundary is generally attributed to the existence of a monoclinic phase in various piezoelectric systems. However, there exist no experimental studies that reveal the role of the monoclinic phase in the piezoelectric behavior in phase-pure ceramics. In this work, a single monoclinic phase has been identified in Pb(Zr,Ti)O_{3} ceramics at room temperature by in situ high-energy synchrotron x-ray diffraction, and its response to electric field has been characterized for the first time. Unique piezoelectric properties of the monoclinic phase in terms of large intrinsic lattice strain and negligible domain switching have been observed. The extensional strain constant d_{33} and the transverse strain constant d_{31} are calculated to be 520 and -200  pm/V, respectively. These large piezoelectric coefficients are mainly due to the large intrinsic lattice strain, with very little extrinsic contribution from domain switching. The unique properties of the monoclinic phase provide new insights into the mechanisms responsible for the piezoelectric properties at the morphotropic phase boundary.

  13. Magnetic nanoparticles based nano-composites: synthesis, contribution of the fillers dispersion and the chains conformation on the reinforcement properties

    International Nuclear Information System (INIS)

    Robbes, Anne-Sophie

    2011-01-01

    The mechanical properties of polymeric nano-composite films can be considerably enhanced by the inclusion of inorganic nanoparticles due to two main effects: (i) the local structure of fillers dispersion and (ii) the potential modification of the chains conformation and dynamics in the vicinity of the filler/polymer interface. However, the precise mechanisms which permit to correlate these contributions at nano-metric scale to the macroscopic mechanical properties of the materials are actually poorly described. In such a context, we have synthesized model nano-composites based on magnetic nanoparticles of maghemite γ-Fe 2 O 3 (naked or grafted with a polystyrene (PS) corona by radical controlled polymerization) dispersed in a PS matrix, that we have characterized by combining small angle scattering (X-Ray and neutron) and transmission electronic microscopy. By playing on different parameters such as the particle size, the concentration, or the size ratio between the grafted chains and the ones of the matrix in the case of the grafted fillers, we have obtained nano-composite films a large panel of controlled and reproducible controlled filler structures, going from individual nanoparticles or fractal aggregates up to the formation of a connected network of fillers. By applying an external magnetic field during the film processing, we succeeded in aligning the different structures along the direction of the field and we obtained materials with remarkable anisotropic reinforcement properties. The conformation of the chains of the matrix, experimentally determined thanks to the specific properties of neutron contrast of the system, is not affected by the presence of the fillers, whatever their confinement, the dispersion the fillers or their chemical state surface. The alignment of the fillers along the magnetic field has allowed us to describe precisely the evolution of the reinforcement modulus of the materials with the structural reorganization of the fillers and

  14. Improvement of thermoelectric properties induced by uniquely ordered lattice field in Bi2Se0.5Te2.5 pillar array

    International Nuclear Information System (INIS)

    Tan, Ming; Hao, Yanming; Wang, Gangzhi

    2014-01-01

    In this study, it was found that uniquely ordered lattice field favors transport of carriers but hinder that of phonons. The n-Bi 2 Se 0.5 Te 2.5 pillar array film was successfully achieved by a simple ion beam assisted deposition technique. This oriented pillar array structure is clear with pillar diameter of about 30 nm, exhibiting a uniquely ordered lattice field. The properties of the ordered Bi 2 Se 0.5 Te 2.5 pillar array were greatly enhanced in comparison with those of the ordinary film. The Bi 2 Se 0.5 Te 2.5 pillar array with a thermoelectric dimensionless figure-of-merit ZT=1.28 was obtained at room temperature. The in-plane transport mechanisms of the ordered pillar array and the ordinary structures, lattice field model, are proposed and investigated. The specially ordered lattice field is the main reason for the properties enhancement observed in the Bi 2 Se 0.5 Te 2.5 film. Introduction of such ordered lattice field into TE films is therefore a very promising approach. - Graphical abstract: In this study, it was found that uniquely ordered lattice field favors transport of carriers but hinder that of phonons. The Bi 2 Se 0.5 Te 2.5 pillar array film with a thermoelectric dimensionless figure-of-merit ZT=1.28 was obtained at room temperature. The in-plane transport mechanisms of the ordered pillar array and the ordinary structures, the lattice field model, are proposed and investigated. The specially ordered lattice field is the main reason for the properties enhancement observed in the Bi 2 Se 0.5 Te 2.5 pillar array. Introduction of such uniquely ordered lattice field into TE films is therefore a very promising approach. In (a) TEM and (b) HRTEM images of the ordered Bi 2 Se 0.5 Te 2.5 column array. - Highlights: • Uniquely ordered Bi 2 Se 0.5 Te 2.5 pillar array was achieved by an IBAD method. • The pillar array with an ordered lattice field exhibits attractive TE property. • The transport mechanism of such ordered pillar array is proposed and

  15. Effect of CNTs dispersion on the thermal and mechanical properties of Cu/CNTs nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Muhsan, Ali Samer, E-mail: alisameer2007@gmail.com, E-mail: faizahmad@petronas.com.my; Ahmad, Faiz, E-mail: alisameer2007@gmail.com, E-mail: faizahmad@petronas.com.my; Yusoff, Puteri Sri Melor Megat Bt, E-mail: puteris@petronas.com.my [Department of Mechanical Engineering, Universiti Teknologi PETRONAS (UTP) (Malaysia); Mohamed, Norani M., E-mail: noranimuti-mohamed@petronas.com.my [Centre of Innovative Nanostructures and Nanodevices (COINN), UTP (Malaysia); Raza, M. Rafi, E-mail: rafirazamalik@gmail.com [Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor (Malaysia)

    2014-10-24

    Modified technique of metal injection molding (MIM) was used to fabricate multiwalled carbon nanotube (CNT) reinforced Cu nanocomposites. The effect of adding different amount of CNTs (0-10 vol.%) on the thermal and mechanical behaviour of the fabricated nanocomposites is presented. Scanning electron microscope analysis revealed homogenous dispersion of CNTs in Cu matrices at different CNTs contents. The experimentally measured thermal conductivities of Cu/CNTs nanocomposites showed extraordinary increase (76% higher than pure sintered Cu) with addition of 10 vol.% CNTs. As compared to the pure sintered Cu, increase in modulus of elasticity (Young's modulus) of Cu/CNTs nanocomposites sintered at 1050°C for 2.5 h was measured to be 48%. However, in case of 7.5 vol.% CNTs, Young's modulus was increased significantly about 51% compared to that of pure sintered Cu.

  16. Inherent optical properties of Zamzam water in the visible spectrum: Dispersion analysis

    International Nuclear Information System (INIS)

    El-Zaiat, S.Y.

    2007-01-01

    Water samples have been taken from Zamzam well that is located in the holy city of Makkah in the Kingdom of Saudi Arabia. Refractive indices of Zamzam water samples have been measured by an Abbe refractometer at six discrete wavelengths across the visible spectrum. Some related optical parameters such as: group refractive index; permittivity; specific refraction; polarizability; reflectance and transmittance have been deduced. Dispersion of these optical parameters across the visible spectrum has been calculated. For comparison, these optical parameters have been determined for two samples of bottled drinking and distilled waters. Also the Abbe number and the single oscillator constants for the three waters have been calculated. Error analyses of the measured and calculated optical parameters have been given. It has been concluded that Zamzam water has special optical parameters that are different than those of bottled bottled drinking and distilled waters. (author)

  17. Electro-optical properties of low viscosity driven holographic polymer dispersed liquid crystals

    Science.gov (United States)

    Moon, K. R.; Bae, S. Y.; Kim, B. K.

    2015-04-01

    Relative diffraction efficiency (RDE), operating voltage, and response times are most important performance characteristics of holographic polymer dispersed liquid crystals (HPDLC). Two types of triallyl isocyanurate (TI) having different structures were incorporated into the conventional transmission grating of HPDLC. Premix viscosity decreased by 13-18% with up to 3% TI, beyond which it increased. TI eliminated induction period and augmented initial grating formation rate at all contents. Saturation RDE increased over 200% while threshold voltage and rise time decreased to about half and 2/3, respectively up to 3% TI, beyond which the tendencies were reversed. Among the two TIs, low viscosity monomer (TA) showed high RDE, while high miscibility monomer (TE) low characteristic voltages and short response times. It is concluded that grating formation is largely favored by low viscosity, while interface tensions and electro-optical performances by miscibility at similar viscosities.

  18. Dispersive properties and attraction instability of low-frequency collective modes in dusty plasmas

    International Nuclear Information System (INIS)

    Tsytovich, V.N.; Rezendes, D.

    1998-01-01

    A dispersion relation for low-frequency collective modes in dusty plasmas is derived with allowance for attractive and repulsive forces arising between the dust grains due to dissipative fluxes of plasma particles onto the grain surfaces. It is shown that these fluxes give rise to dust attraction instabilities, which are similar to the gravitational instability. In the range of wave numbers corresponding to the stability domain, two types of dust sound waves arise, depending on whether the wavelengths of the collective modes are longer or shorter than the mean free path of the plasma particles (i.e., the distance they travel before they collide with dust grains). The dispersion relation derived is valid for any ratio between the wavelength of the perturbations and the mean free path and encompasses the entire range of intermediate wave numbers. The critical wave numbers that determine the threshold for the onset of attraction instability, which is similar to the Jeans instability, can, in particular, lie within this range. The thresholds for attraction instability and the instability growth rates are obtained numerically for a wide range of the plasma parameters (such as the ratio of the ion temperature to the electron temperature) that are of interest for present-day experiments with dust crystals, plasma etching, and space plasma studies. Computer simulation shows that, in the nonlinear stage, the attraction instability causes the dust cloud to collapse, which leads to the formation of dust plasma crystals. Our investigation makes it possible to trace the processes in the initial stage of dust crystallization. Results are obtained for hydrogen and silicon plasmas, which are most typical of laboratory experiments

  19. Magnetic properties of Mn-oxide nanoparticles dispersed in an amorphous SiO2 matrix

    Science.gov (United States)

    Milivojević, D.; Babić-Stojić, B.; Jokanović, V.; Jagličić, Z.; Makovec, D.

    2011-03-01

    Samples of Mn-oxide nanoparticles dispersed in an amorphous SiO2 matrix with manganese concentration 0.7 and 3 at% have been synthesized by a sol-gel method. Transmission electron microscopy analysis has shown that the samples contain agglomerates of amorphous silica particles 10-20 nm in size. In silica matrix two types of Mn-rich particles are dispersed, smaller nanoparticles with dimensions between 3 and 10 nm, and larger crystalline areas consisting of aggregates of the smaller nanoparticles. High-temperature magnetic susceptibility study reveals that dominant magnetic phase at higher temperatures is λ-MnO2. At temperatures below TC=43 K strong ferrimagnetism originating from the minor Mn3O4 phase masks the relatively weak magnetism of λ-MnO2 with antiferromagnetic interactions. Magnetic field dependence of the maximum in the zero-field-cooled magnetization for both the samples in the vicinity of 40 K, and a frequency shift of the real component of the ac magnetic susceptibility in the sample with 3 at% Mn suggest that the magnetic moments of the smaller Mn3O4 nanoparticles with dimensions below 10 nm are exposed to thermally activated blocking process just below the Curie temperature TC. Appearance of a maximum in the zero-field-cooled magnetization for both the samples below 10 K indicates possible spin glass freezing of the magnetic moments at low temperatures which might occur in the geometrically frustrated Mn sublattice of the λ-MnO2 crystal structure.

  20. Wheat gluten/montmorillonite biocomposites: Effect of pH on the mechanical properties and clay dispersion

    Directory of Open Access Journals (Sweden)

    E. Cortes-Trivino

    2018-07-01

    Full Text Available The addition of inorganic fillers into a bioplastic could increase its mechanical properties, which will be influenced strongly by the type of the clay dispersion. In this work, we have used montmorillonite nanoclays (MMT to prepare biocomposites by means of an extrusion process. We present herein the effect of the pH and the addition of montmorillonite nanoclays (MMT on the barrier and mechanical properties of wheat gluten based bioplastics. The pH of the samples was modified by adding aqueous solution of a strong acid or base (H2SO4 and NaOH. Tensile, dynamic mechanical thermal analysis (DMTA, water absorption and X-ray tests were carried out to study the influence of the above-mentioned variables on the physicochemical properties and rheological behaviour of bioplastics and biocomposites obtained. Tensile results showed that both Young’s modulus and tensile strength are higher at unmodified pH. However, the addition of MMT to an alkaline biopolymer matrix produced remarkable improvements in the rheological and mechanical properties because of a high exfoliation of the nanoclay noticeable in X-ray results. To summarise, extrusion process and the use of nanoclays present an excellent opportunity to develop wheat gluten bioplastics able to replace conventional products.

  1. Water-dispersible sugar-coated iron oxide nanoparticles. An evaluation of their relaxometric and magnetic hyperthermia properties.

    Science.gov (United States)

    Lartigue, Lenaic; Innocenti, Claudia; Kalaivani, Thangavel; Awwad, Azzam; Sanchez Duque, Maria del Mar; Guari, Yannick; Larionova, Joulia; Guérin, Christian; Montero, Jean-Louis Georges; Barragan-Montero, Véronique; Arosio, Paolo; Lascialfari, Alessandro; Gatteschi, Dante; Sangregorio, Claudio

    2011-07-13

    Synthesis of functionalized magnetic nanoparticles (NPs) for biomedical applications represents a current challenge. In this paper we present the synthesis and characterization of water-dispersible sugar-coated iron oxide NPs specifically designed as magnetic fluid hyperthermia heat mediators and negative contrast agents for magnetic resonance imaging. In particular, the influence of the inorganic core size was investigated. To this end, iron oxide NPs with average size in the range of 4-35 nm were prepared by thermal decomposition of molecular precursors and then coated with organic ligands bearing a phosphonate group on one side and rhamnose, mannose, or ribose moieties on the other side. In this way a strong anchorage of the organic ligand on the inorganic surface was simply realized by ligand exchange, due to covalent bonding between the Fe(3+) atom and the phosphonate group. These synthesized nanoobjects can be fully dispersed in water forming colloids that are stable over very long periods. Mannose, ribose, and rhamnose were chosen to test the versatility of the method and also because these carbohydrates, in particular rhamnose, which is a substrate of skin lectin, confer targeting properties to the nanosystems. The magnetic, hyperthermal, and relaxometric properties of all the synthesized samples were investigated. Iron oxide NPs of ca. 16-18 nm were found to represent an efficient bifunctional targeting system for theranostic applications, as they have very good transverse relaxivity (three times larger than the best currently available commercial products) and large heat release upon application of radio frequency (RF) electromagnetic radiation with amplitude and frequency close to the human tolerance limit. The results have been rationalized on the basis of the magnetic properties of the investigated samples.

  2. Soybean-oil-based waterborne polyurethane dispersions: effects of polyol functionality and hard segment content on properties.

    Science.gov (United States)

    Lu, Yongshang; Larock, Richard C

    2008-11-01

    The environmentally friendly vegetable-oil-based waterborne polyurethane dispersions with very promising properties have been successfully synthesized without difficulty from a series of methoxylated soybean oil polyols (MSOLs) with different hydroxyl functionalities ranging from 2.4 to as high as 4.0. The resulting soybean-oil-based waterborne polyurethane (SPU) dispersions exhibit a uniform particle size, which increases from about 12 to 130 nm diameter with an increase in the OH functionality of the MSOL from 2.4 to 4.0 and decreases with increasing content of the hard segments. The structure and thermophysical and mechanical properties of the resulting SPU films, which contain 50-60 wt % MSOL as renewable resources, have been studied by Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, transmission electron microscopy, and mechanical testing. The experimental results reveal that the functionality of the MSOLs and the hard segment content play a key role in controlling the structure and the thermophysical and mechanical properties of the SPU films. These novel films exhibit tensile stress-strain behavior ranging from elastomeric polymers to rigid plastics and possess Young's moduli ranging from 8 to 720 MPa, ultimate tensile strengths ranging from 4.2 to 21.5 MPa, and percent elongation at break values ranging from 16 to 280%. This work has addressed concerns regarding gelation and higher cross-linking caused by the high functionality of vegetable-oil-based polyols. This article reports novel environmentally friendly biobased SPU materials with promising applications as decorative and protective coatings.

  3. Reversible pH-Sensitive Chitosan-Based Hydrogels. Influence of Dispersion Composition on Rheological Properties and Sustained Drug Delivery

    Directory of Open Access Journals (Sweden)

    Nieves Iglesias

    2018-04-01

    Full Text Available The present work deals with the synthesis of micro-structured biomaterials based on chitosan (CTS for their applications as biocompatible carriers of drugs and bioactive compounds. Twelve dispersions were prepared by means of functional cross-linking with tricarballylic acid (TCA; they were characterized by Fourier transform infrared spectroscopy (FT-IR, modulated temperature differential scanning calorimetry (MTDSC and scanning electron microscopy (SEM, and their rheological properties were studied. To the best of the authors’ knowledge, no study has been carried out on the influence of CTS concentration, degree of cross-linking and drug loading on chitosan hydrogels for drug delivery systems (DDS and is investigated herein for the first time. The influence of dispersion composition (polymer concentration and degree of cross-linking revealed to exert a marked impact on its rheological properties, going from liquid-like to viscoelastic gels. The release profiles of a model drug, diclofenac sodium (DCNa, as well as their relationships with polymer concentration, drug loading and degree of cross-linking were evaluated. Similar to the findings on rheological properties, a wide range of release profiles was encountered. These formulations were found to display a well-controlled drug release strongly dependent on the formulation composition. Cumulative drug release under physiological conditions for 96 h ranged from 8% to 67%. For comparative purpose, Voltaren emulgel® from Novartis Pharmaceuticals was also investigated and the latter was the formulation with the highest cumulative drug release (85%. Some formulations showed similar spreadability values to the commercial hydrogel. The comparative study of three batches confirmed the reproducibility of the method, leading to systems particularly suitable for their use as drug carriers.

  4. The study of polymeric hydro-gels with unique properties obtained by polymerization with gamma radiation processing

    International Nuclear Information System (INIS)

    Dragusin, M.

    1995-01-01

    This thesis presents the work carried out on polymeric hydro-gels obtained by radiation processing using 60 Co gamma rays from the irradiation facility IETI-10.000 (10 k Ci), and on the polymeric hydro-gels obtained by irradiation with the electron beams from a linear accelerator (6 MeV). The aim of the study was to determine the effect of the rate dose and total dose absorbed in the materials. There are presented the preparation methods of homo- and co-polymer hydro-gels (acrylics, namely anionic and neutral monomers (acrylamide, acrylic acid, vinyl acetate) and cationic monomers (di-methyl di-allyl ammonium chloride)) such as floculants, additives, absorbers, etc. Concerning with these we have analysed the preparation methods, the mechanical, thermal, diffusivity, and swelling properties of polymeric hydro-gels in a large variety of gels of type I or II. The technological aspects and end use were studied in connection with the characteristics of the radiation processing of these hydro-gels as a function of chemical composition rate and absorbed dose, swelling degree (low and very high hydro-soluble), mechanical and diffusional properties. (author) 33 figs., 12 tabs., 101 refs

  5. Unique biological properties of catalytic domain directed human anti-CAIX antibodies discovered through phage-display technology.

    Directory of Open Access Journals (Sweden)

    Chen Xu

    2010-03-01

    Full Text Available Carbonic anhydrase IX (CAIX, gene G250/MN-encoded transmembrane protein is highly expressed in various human epithelial tumors such as renal clear cell carcinoma (RCC, but absent from the corresponding normal tissues. Besides the CA signal transduction activity, CAIX may serve as a biomarker in early stages of oncogenesis and also as a reliable marker of hypoxia, which is associated with tumor resistance to chemotherapy and radiotherapy. Although results from preclinical and clinical studies have shown CAIX as a promising target for detection and therapy for RCC, only a limited number of murine monoclonal antibodies (mAbs and one humanized mAb are available for clinical testing and development. In this study, paramagnetic proteoliposomes of CAIX (CAIX-PMPLs were constructed and used for anti-CAIX antibody selection from our 27 billion human single-chain antibody (scFv phage display libraries. A panel of thirteen human scFvs that specifically recognize CAIX expressed on cell surface was identified, epitope mapped primarily to the CA domain, and affinity-binding constants (KD determined. These human anti-CAIX mAbs are diverse in their functions including induction of surface CAIX internalization into endosomes and inhibition of the carbonic anhydrase activity, the latter being a unique feature that has not been previously reported for anti-CAIX antibodies. These human anti-CAIX antibodies are important reagents for development of new immunotherapies and diagnostic tools for RCC treatment as well as extending our knowledge on the basic structure-function relationships of the CAIX molecule.

  6. Structural characterization of the bacterial proteasome homolog BPH reveals a tetradecameric double-ring complex with unique inner cavity properties.

    Science.gov (United States)

    Fuchs, Adrian C D; Maldoner, Lorena; Hipp, Katharina; Hartmann, Marcus D; Martin, Jörg

    2018-01-19

    Eukaryotic and archaeal proteasomes are paradigms for self-compartmentalizing proteases. To a large extent, their function requires interplay with hexameric ATPases associated with diverse cellular activities (AAA+) that act as substrate unfoldases. Bacteria have various types of self-compartmentalizing proteases; in addition to the proteasome itself, these include the proteasome homolog HslV, which functions together with the AAA+ HslU; the ClpP protease with its partner AAA+ ClpX; and Anbu, a recently characterized ancestral proteasome variant. Previous bioinformatic analysis has revealed a novel bacterial member of the proteasome family Betaproteobacteria proteasome homolog (BPH). Using cluster analysis, we here affirmed that BPH evolutionarily descends from HslV. Crystal structures of the Thiobacillus denitrificans and Cupriavidus metallidurans BPHs disclosed a homo-oligomeric double-ring architecture in which the active sites face the interior of the cylinder. Using small-angle X-ray scattering (SAXS) and electron microscopy averaging, we found that BPH forms tetradecamers in solution, unlike the dodecamers seen in HslV. Although the highly acidic inner surface of BPH was in striking contrast to the cavity characteristics of the proteasome and HslV, a classical proteasomal reaction mechanism could be inferred from the covalent binding of the proteasome-specific inhibitor epoxomicin to BPH. A ligand-bound structure implied that the elongated BPH inner pore loop may be involved in substrate recognition. The apparent lack of a partner unfoldase and other unique features, such as Ser replacing Thr as the catalytic residue in certain BPH subfamilies, suggest a proteolytic function for BPH distinct from those of known bacterial self-compartmentalizing proteases. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. Effect of Fatty acids and beeswax addition on properties of sodium caseinate dispersions and films.

    Science.gov (United States)

    Fabra, M J; Jiménez, A; Atarés, L; Talens, P; Chiralt, A

    2009-06-08

    Edible films based on sodium caseinate and different saturated fatty acids, oleic acid, or beeswax were formulated. Film-forming emulsions were characterized in terms of particle size distribution, rheological behavior and surface tension. In order to evaluate the influence of lipids on sodium caseinate matrices, mechanical, optical, and water vapor barrier properties were studied, taking into account the effect of water content and film structure on such properties. Saturated fatty acids affected the film properties in a particular way due to the formation of bilayer structures which limited water vapor permeability, giving rise to nonflexible and more opaque films. Oleic acid and beeswax were less effective as water vapor barriers, although the former imparted more flexibility to the caseinate films and did not reduce the film transparency notably.

  8. Effect of the Zr elements with thermal properties changes of U-7Mo-xZr/Al dispersion fuel

    International Nuclear Information System (INIS)

    Supardjo; Agoeng Kadarjono; Boybul; Aslina Br Ginting

    2016-01-01

    Thermal properties data of nuclear fuel is required as input data to predict material properties change phenomenon during the fabrication process and irradiated in a nuclear reactor. Study the influence of Zr element in the U-7Mo-xZr/Al (x = 1%, 2% and 3%) fuel dispersion to changes in the thermal properties at various temperatures have been stiffened. Thermal analysis includes determining the melting temperature, enthalpy, and phase changes made using Differential Thermal Analysis (DTA) in the temperature range between 30 °C up to 1400 °C, while the heat capacity of U-7Mo-xZr alloy and U-7Mo-xZr/Al dispersion fuel using Differential Scanning Calorimeter (DSC) at room temperature up to 450 °C. Thermal analyst data DTA shows that Zr levels of all three compositions showed a similar phenomenon. At temperatures between 565.60 °C - 584.98 °C change becomes α + δ to α + γ phase and at 649.22 °C – 650.13 °C happen smelting Al matrix Occur followed by a reaction between Al matrix with U-7Mo-xZr on 670.38 °C - 673.38 °C form U (Al, Mo)x Zr. Furthermore a phase change α + β becomes β + γ Occurs at temperatures 762.08 °C - 776.33 °C and diffusion between the matrix by U-7Mo-xZr/Al on 853.55 °C - 875.20 °C. Every phenomenon that Occurs, enthalpy posed a relative stable. Consolidation of uranium Occur in 1052.42 °C - 1104.99 °C and decomposition reaction of U (Al, Mo)x and U (Al, Zr)_x becomes (UAl_4, UAl_3, UAl_2), U-Mo, and UZr on 1328,34 °C - 1332,06 °C , The existence of Zr in U-Mo alloy increases the heat capacity of the U-7Mo-xZr/Al, dispersion fuel and the higher heat capacity of Zr levels increased due to interactions between the atoms of Zr with Al matrix so that the heat absorbed by the fuel increase. (author)

  9. Microstructural evolution and some mechanical properties of nanosized yttrium oxide dispersion strengthened 13Cr steel

    International Nuclear Information System (INIS)

    Nguyen, Van Tich; Doan, Dinh Phuong; Tran, Tran BaoTrung; Luong, Van Duong; Nguyen, Van An; Phan, Anh Tu

    2010-01-01

    Oxide dispersion strengthened (ODS) steels, manufactured by a mechanical alloying method, during the past few years, appear to be promising candidates for structural applications in nuclear power plants. The purpose of this work is to elaborate the manufacturing processes of ODS 13Cr steel with the addition of 1.0 wt% yttrium oxide through the powder metallurgy route using the high energy ball mill. Microstructural analysis by scanning electron microscopy (SEM), x-ray diffraction (XRD) and hardness testing have been used to optimize the technological parameters of milling, hot isostatic pressing and heat-treatment processes. The steel hardness increases with decreasing particle size of 13Cr ODS steel. The best hardness was obtained from more than 70 h of milling in the two tanks planetary ball mill or 30 h of milling in the one tank planetary ball mill and hot isostatic pressing at 1150 °C . The particle size of the steel is less than 100 nm, and the density and hardness are about 7.3 g cm −3 and 490 HB, respectively

  10. Experimental and Numerical Study on the Dispersion Patterns and Penetration Properties of MEFP with Seven Arc-Cone Liners

    Directory of Open Access Journals (Sweden)

    JianFeng Liu

    Full Text Available Abstract A new MEFP warhead with seven arc-cone liners which can form 7, 13 or 19 penetrators at different standoffs is designed. Dispersion patterns and penetration properties of MEFP are performed on five #45 steel targets of dimension 160cm x 160cm x 1.5cm at various standoffs (45cm, 60cm, 80cm, 120cm, 170cm. It reaches the conclusion that every surrounding liner is broken into three penetrators during the formation process of MEFP and a group of aimable penetrators consisting a central projectile surrounded by 18 penetrators is finally formed. Maximum divergence angle of surrounding penetrator is 9.8° and the damage area reaches 0.37m2 at 1.7m. A nonlinear surface fitting about perforations information on the targets at different standoffs provides a method of predicting the dispersion patterns of MEFP. Once initiated, damage probability for defeating light armor of MEFP warhead with seven arc-cone liners is significantly improved and the results provide important reference to the design and optimization of MEFP warhead in engineering.

  11. Evolution of Microstructure and Mechanical Properties of Oxide Dispersion Strengthened Steels Made from Water-Atomized Ferritic Powder

    Science.gov (United States)

    Arkhurst, Barton Mensah; Kim, Jeoung Han

    2018-05-01

    Nano-structured oxide dispersion strengthened (ODS) steels produced from a 410L stainless steel powder prepared by water-atomization was studied. The influences of Ti content and milling time on the microstructure and the mechanical properties were analysed. It was found that the ODS steels made from the Si bearing 410L powder contained Y-Ti-O, Y-Ti-Si-O, Y-Si-O, and TiO2 oxides. Most nanoparticles produced after 80 h of milling were aggregated nanoparticles; however, after 160 h of milling, most aggregated nanoparticles dissociated into smaller individual nanoparticles. Perfect mixing of Y and Ti was not achieved even after the longer milling time of 160 h; instead, the longer hours of milling rather resulted in Si incorporation into the Y-Ti-O rich nanoparticles and a change in the matrix morphology from an equiaxed microstructure to a tempered martensite-like microstructure. The overall micro-hardness of the ODS steel increased with the increase of milling time. After 80 and 160 h, the microhardnesses were over 400 HV, which primarily resulted from the finer dispersed nanoparticles and in part to the formation of martensitic phases. Tensile strength of the 410L ODS steels was comparable with that of ODS steel produced from gas-atomized powder.

  12. Effect of cellulose nanocrystals (CNC) particle morphology on dispersion and rheological and mechanical properties of polypropylene/CNC nanocomposites.

    Science.gov (United States)

    Khoshkava, Vahid; Kamal, Musa R

    2014-06-11

    Polypropylene (PP) nanocomposites containing spray-dried cellulose nanocrystals (CNC), freeze-dried CNC, and spray-freeze-dried CNC (CNCSFD) were prepared via melt mixing in an internal batch mixer. Polarized light, scanning electron, and atomic force microscopy showed significantly better dispersion of CNCSFD in PP/CNC nanocomposites compared with the spray-dried and freeze-dried CNCs. Rheological measurements, including linear and nonlinear viscoelastic tests, were performed on PP/CNC samples. The microscopy results were supported by small-amplitude oscillatory shear tests, which showed substantial rises in the magnitudes of key rheological parameters of PP samples containing CNCSFD. Steady-shear results revealed a strong shear thinning behavior of PP samples containing CNCSFD. Moreover, PP melts containing CNCSFD exhibited a yield stress. The magnitude of the yield stress and the degree of shear thinning behavior increased with CNCSFD concentration. It was found that CNCSFD agglomerates with a weblike structure were more effective in modifying the rheological properties. This effect was attributed to better dispersion of the agglomerates with the weblike structure. Dynamic mechanical analysis showed considerable improvement in the modulus of samples containing CNCSFD agglomerates. The percolation mechanical model with modified volume percolation threshold and filler network strength values and the Halpin-Kardos model were used to fit the experimental results.

  13. Reproducibility of aluminum foam properties: Effect of precursor distribution on the structural anisotropy and the collapse stress and its dispersion

    International Nuclear Information System (INIS)

    Nosko, M.; Simancik, F.; Florek, R.

    2010-01-01

    The porous structure of aluminum foam manufactured through the foaming of precursors containing blowing agent is stochastic in nature, usually with a random distribution of pores of different size and shape, creating difficulties in the modeling and prediction of foam properties. In this study, the effect of the initial location of the precursor material in the mold on the foam structure and compression behavior was investigated. Structural characterization showed that the porosity distribution, surface skin thickness and pore orientation was affected by the location of the precursors in the mold and by the extrusion direction of the precursors. Moreover, compression tests demonstrated a significant effect of the structural anisotropy on the collapse stress and its dispersion. The collapse stress of the foam increased if the loading was performed parallel to the thicker surface skin or parallel to the preferential pore orientation, leading to a 20% difference in collapse stress. The dispersion of the collapse stress could be significantly decreased if the loading was performed with regard to the structural anisotropy.

  14. The Relationship between the Monomer Chain Length and the Electro-Optical Properties of Polymer Dispersed Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Liu J.

    2016-03-01

    Full Text Available Five polymers dispersed liquid crystalline (LC films were fabricated using photo-polymerizable monomers with different lengths of carbon chains. These LC films have shown different electro-optical (EO properties. Through their SEM pictures, the relationship between the linear electro-optical effect and the mesh size of the polymer network was explored. With the increase of number of photo-polymerizable monomers, the mesh size of the polymer network would become larger. So the liquid crystal molecules would be easily oriented in the electric field and therefore, the threshold voltage and saturation voltage would decrease. The open state response times were also reduced and the off state response times would be extended. The DFT simulations have shown principal role of the ground state dipole moments in the observed electro-optical efficiency.

  15. Thermally and optically tunable lasing properties from dye-doped holographic polymer dispersed liquid crystal in capillaries

    Science.gov (United States)

    Chen, Maozhou; Dai, Haitao; Wang, Dongshuo; Yang, Yue; Luo, Dan; Zhang, Xiaodong; Liu, Changlong

    2018-03-01

    In this paper, we investigated tunable lasing properties from the dye-doped holographic polymer dispersed liquid crystal (HPDLC) gratings in capillaries with thermal and optical manners. The thermally tunable range of the lasing from the dye-doped HPDLC reached 8.60 nm with the temperature ranging from 23 °C to 50 °C. The optically tunable laser emission was achieved by doping azo-dye in HPDLC. The transition of azo-dye from trans- to cis-state could induce the reorientation of LC molecules after UV light irradiation, which resulted in the variation of refractive index contrast of LC-rich/polymer-rich layer in HPDLC. Experimentally, the emission wavelength of lasing showed a blueshift (about 2 nm) coupled with decreasing output intensities. The tunable laser based on HPDLC may enable more applications in laser displays, optical communication, biosensors, etc.

  16. Unique properties of multiple tandem copies of the M26 recombination hotspot in mitosis and meiosis in Schizosaccharomyces pombe.

    Science.gov (United States)

    Steiner, Walter W; Recor, Chelsea L; Zakrzewski, Bethany M

    2016-11-15

    The M26 hotspot of the fission yeast Schizosaccharomyces pombe is one of the best-characterized eukaryotic hotspots of recombination. The hotspot requires a seven bp sequence, ATGACGT, that serves as a binding site for the Atf1-Pcr1 transcription factor, which is also required for activity. The M26 hotspot is active in meiosis but not mitosis and is active in some but not all chromosomal contexts and not on a plasmid. A longer palindromic version of M26, ATGACGTCAT, shows significantly greater activity than the seven bp sequence. Here, we tested whether the properties of the seven bp sequence were also true of the longer sequence by placing one, two, or three copies of the sequence into the ade6 gene, where M26 was originally discovered. These constructs were tested for activity when located on a plasmid or on a chromosome in mitosis and meiosis. We found that two copies of the 10bp M26 motif on a chromosome were significantly more active for meiotic recombination than one, but no further increase was observed with three copies. However, three copies of M26 on a chromosome created an Atf1-dependent mitotic recombination hotspot. When located on a plasmid, M26 also appears to behave as a mitotic recombination hotspot; however, this behavior most likely results from Atf1-dependent inter-allelic complementation between the plasmid and chromosomal ade6 alleles. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. SiCO-doped carbon fibers with unique dual superhydrophilicity/superoleophilicity and ductile and capacitance properties.

    Science.gov (United States)

    Lu, Ping; Huang, Qing; Mukherjee, Amiya; Hsieh, You-Lo

    2010-12-01

    Silicon oxycarbide (SiCO) glass-doped carbon fibers with an average diameter of 163 nm were successfully synthesized by electrospinning polymer mixtures of preceramic precursor polyureasilazane (PUS) and carbon precursor polyacrylonitrile (PAN) into fibers then converting to ceramic/carbon hybrid via cross-linking, stabilization, and pyrolysis at temperatures up to 1000 °C. The transformation of PUS/PAN polymer precursors to SiCO/carbon structures was confirmed by EDS and FTIR. Both carbon and SiCO/carbon fibers were amorphous and slightly oxidized. Doping with SiCO enhanced the thermal stability of carbon fibers and acquired new ductile behavior in the SiCO/carbon fibers with significantly improved flexibility and breaking elongation. Furthermore, the SiCO/carbon fibers exhibited dual superhydrophilicity and superoleophilicity with water and decane absorbing capacities of 873 and 608%, respectively. The cyclic voltammetry also showed that SiCO/carbon composite fibers possess better capacitor properties than carbon fibers.

  18. Unique virulence properties of Yersinia enterocolitica O:3--an emerging zoonotic pathogen using pigs as preferred reservoir host.

    Science.gov (United States)

    Valentin-Weigand, Peter; Heesemann, Jürgen; Dersch, Petra

    2014-10-01

    Enteropathogenic Yersinia enterocolitica bioserotype 4/O:3 are the most frequent cause of human yersiniosis worldwide with symptoms ranging from mild diarrhea to severe complications of mesenteric lymphadenitis, liver abscesses and postinfectious extraintestinal sequelae. The main reservoir host of 4/O:3 strains are pigs, which represent a substantial disease-causing potential for humans, as they are usually asymptomatic carriers. Y. enterocolitica O:3 initiates infections by tight attachment to the intestinal mucosa. Colonization of the digestive tract is frequently followed by invasion of the intestinal layer primarily at the follicle-associated epithelium, allowing the bacteria to propagate in the lamina propria and disseminate into deeper tissues. Molecular characterization of Y. enterocolitica O:3 isolates led to the identification of (i) alternative virulence and fitness factors and (ii) small genetic variations which cause profound changes in their virulence gene expression pattern (e.g. constitutive expression of the primary invasion factor InvA). These changes provoke a major difference in the virulence properties, i.e. reduced colonization of intestinal tissues in mice, but improved long-term colonization in the pig intestine. Y. enterocolitica O:3 strains cause also a considerably lower level of proinflammatory cytokine IL-8 and higher levels of the anti-inflammatory cytokine IL-10 in porcine primary macrophages, as compared to murine macrophages, which could contribute to limiting inflammation, immunopathology and severity of the infection in pigs. Copyright © 2014 Elsevier GmbH. All rights reserved.

  19. Kainari, a Unique Greek Traditional Herbal Tea, from the Island of Lesvos: Chemical Analysis and Antioxidant and Antimicrobial Properties

    Directory of Open Access Journals (Sweden)

    Evangelia Bampali

    2018-01-01

    Full Text Available The chemical composition, as well as the total phenolic content (TPC and the potential antioxidant and antimicrobial activity, of three Kainari-herbal tea samples from different areas of Lesvos Island (Greece was evaluated. The rich aroma of the mixtures was studied through GC-MS, as well as through Headspace Solid-Phase Microextraction (HS-SPME/GC-MS analyses. Cinnamon, clove, nutmeg, pepper, and ginger were identified as main ingredients, while, throughout the chemical analysis of the volatiles of one selected sample, several secondary metabolites have been isolated and identified on the basis of GC-MS as well as spectral evidence as eugenol, cinnamic aldehyde and myristicin, cinnamyl alcohol, alpha-terpinyl acetate, and β-caryophyllene. Furthermore, two food dyes, azorubine and amaranth, were also isolated and identified from the infusions. The total phenolic content was estimated and the free radical scavenging activity was determined by DPPH and ABTS assays and the antimicrobial activity of the extracts was tested showing a very interesting profile against all the assayed microorganisms. Due to its very pleasant aroma and taste properties as well as to its bioactivities, Kainari-herbal tea could be further proposed as functional beverage.

  20. Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films.

    Science.gov (United States)

    Sun, Yujian; Zhang, Cuihong; Zhou, Le; Fang, Hua; Huang, Jianhua; Ma, Haipeng; Zhang, Yi; Yang, Jie; Zhang, Lan-Ying; Song, Ping; Gao, Yanzi; Xiao, Jiumei; Li, Fasheng; Li, Kexuan

    2016-12-30

    Polymer-dispersed liquid crystal (PDLC) films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.

  1. Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films

    Directory of Open Access Journals (Sweden)

    Yujian Sun

    2016-12-01

    Full Text Available Polymer-dispersed liquid crystal (PDLC films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.

  2. Magnetic properties of Co and Ni based alloy nanoparticles dispersed in a silica matrix

    Energy Technology Data Exchange (ETDEWEB)

    De Julian Fernandez, C. E-mail: dejulian@padova.infm.it; Sangregorio, C.; Mattei, G.; Maurizio, C.; Battaglin, G.; Gonella, F.; Lascialfari, A.; Lo Russo, S.; Gatteschi, D.; Mazzoldi, P.; Gonzalez, J.M.; D' Acapito, F

    2001-04-01

    A comparative study of the magnetic properties of Co and Ni based alloy nanoparticles (Ni-Co, Ni-Cu and Co-Cu) formed in a silica matrix by ion implantation is presented. Different ion doses and implantation sequences were realized in order to obtain different nanostructures. The structural and magnetic properties observed for the Cu{sub 50}Ni{sub 50} nanoparticles are similar to those of the Cu{sub 60}Ni{sub 40} bulk alloy. The crystal structure of Co{sub x}Ni{sub 1-x} (0{<=}x{<=}1) nanoparticles is similar to that of the corresponding bulk alloy. The magnetic properties depend on the ion-implanted dose and on the alloy composition. The samples prepared by implanting a 15x10{sup 16} ions/cm{sup 2} total dose contain nanoparticles, which are superparamagnetic at room temperature and their magnetic behavior is influenced by dipolar interparticle interactions. The magnetization of the CoNi samples at high magnetic field is larger than that of the corresponding bulk alloy and follows the same composition dependence of that quantity measured in the alloy.

  3. Magnetic properties of Co and Ni based alloy nanoparticles dispersed in a silica matrix

    International Nuclear Information System (INIS)

    De Julian Fernandez, C.; Sangregorio, C.; Mattei, G.; Maurizio, C.; Battaglin, G.; Gonella, F.; Lascialfari, A.; Lo Russo, S.; Gatteschi, D.; Mazzoldi, P.; Gonzalez, J.M.; D'Acapito, F.

    2001-01-01

    A comparative study of the magnetic properties of Co and Ni based alloy nanoparticles (Ni-Co, Ni-Cu and Co-Cu) formed in a silica matrix by ion implantation is presented. Different ion doses and implantation sequences were realized in order to obtain different nanostructures. The structural and magnetic properties observed for the Cu 50 Ni 50 nanoparticles are similar to those of the Cu 60 Ni 40 bulk alloy. The crystal structure of Co x Ni 1-x (0≤x≤1) nanoparticles is similar to that of the corresponding bulk alloy. The magnetic properties depend on the ion-implanted dose and on the alloy composition. The samples prepared by implanting a 15x10 16 ions/cm 2 total dose contain nanoparticles, which are superparamagnetic at room temperature and their magnetic behavior is influenced by dipolar interparticle interactions. The magnetization of the CoNi samples at high magnetic field is larger than that of the corresponding bulk alloy and follows the same composition dependence of that quantity measured in the alloy

  4. Unique Optoelectronic Structure and Photoreduction Properties of Sulfur-Doped Lead Chromates Explaining Their Instability in Paintings.

    Science.gov (United States)

    Rahemi, Vanoushe; Sarmadian, Nasrin; Anaf, Willemien; Janssens, Koen; Lamoen, Dirk; Partoens, Bart; De Wael, Karolien

    2017-03-21

    Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artist's material from the second quarter of the 19th century. The color of the pigment, in which the chromate ion acts as a chromophore, is related to its chemical composition (PbCr 1-x S x O 4 , with 0 ≤ x ≤ 0.8) and crystalline structure (monoclinic/orthorhombic). Their shades range from the yellow-orange to the paler yellow tones with increasing sulfate amount. These pigments show remarkable signs of degradation after limited time periods. Pure PbCrO 4 (crocoite in its natural form) has a deep yellow color and is relatively stable, while the coprecipitate with lead sulfate (PbCr 1-x S x O 4 ) has a paler shade and seems to degrade faster. This degradation is assumed to be related to the reduction of Cr(VI) to Cr(III). We show that, when the the sulfur(S)-content in chrome yellow increases, the band gap increases. Typically, when increasing the band gap, one might assume that a decrease in photoactivity is the result. However, the photoactivity relative to the Cr content and, thus, Cr reduction of sulfur-rich PbCr 1-x S x O 4 is found to be much higher compared to the sulfur-poor or nondoped lead chromates. This discrepancy can be explained by the evolution of the crystal and electronic structure as a function of the sulfur content: first-principles density functional theory calculations show that both the absorption coefficient and reflection coefficients of the lead chromates change as a result of the sulfate doping in such a way that the generation of electron-hole pairs under illumination relative to the total Cr content increases. These changes in the material properties explain why paler shade yellow colors of this pigment are more prone to discoloration. The electronic structure calculations also demonstrate that lead chromate and its coprecipitates are p-type semiconductors, which explains the observed reduction reaction. Because understanding this phenomenon is

  5. Unique negative permittivity of the pseudo conducting radial zinc oxide-poly(vinylidene fluoride) nanocomposite film: Enhanced dielectric and electromagnetic interference shielding properties

    Energy Technology Data Exchange (ETDEWEB)

    Aepuru, Radhamanohar [Department of Materials Engineering, Defence Institute of Advanced Technology, Girinagar, Pune 411025 (India); Bhaskara Rao, B.V.; Kale, S.N. [Department of Applied Physics, Defence Institute of Advanced Technology, Pune 411025 (India); Panda, H.S., E-mail: himanshusp@diat.ac.in [Department of Materials Engineering, Defence Institute of Advanced Technology, Girinagar, Pune 411025 (India)

    2015-11-01

    Flower like radial zinc oxide (RZnO) was prepared by using a facile solvothermal method and used to prepare poly(vinylidene fluoride) (PVDF) based nanocomposites. Structural informations of the samples are analyzed by X-ray diffraction and correlated with high resolution transmission electron microscopy along with high annular angular dark field scanning transmission electron microscopy (HAADF-STEM). For the first time, stability studies are carried out by solvent relaxation nuclear magnetic resonance experiments. Dielectric studies of the PVDF and PVDF-RZnO nanocomposites are reported over the wide range of frequency (0.01 Hz–1 MHz) and temperature (25–90 °C). Dielectric property of the PVDF-RZnO nanocomposites was significantly improved wrt filler percentage in PVDF. Unique negative permittivity was observed in the composites having higher filler content (>40 wt%) typically at low frequencies. First time, it is observed that the higher RZnO content in PVDF results the formation of pseudo conducting network and hence improved the electromagnetic shielding efficiency (85%) than PVDF and PVDF-commercial ZnO composites. - Highlights: • Radial ZnO-PVDF nanocomposites were fabricated by using solution casting. • Pseudo conducting network is confirmed through cryo-fracture morphology study. • Stability study of the nano fillers was performed in the polymer matrix. • Unique negative permittivity behavior of the nanocomposites was observed. • EMI shielding property of the radial ZnO-PVDF nanocomposites was performed.

  6. An integrated Drosophila model system reveals unique properties for F14512, a novel polyamine-containing anticancer drug that targets topoisomerase II.

    Directory of Open Access Journals (Sweden)

    Sonia Chelouah

    Full Text Available F14512 is a novel anti-tumor molecule based on an epipodophyllotoxin core coupled to a cancer-cell vectoring spermine moiety. This polyamine linkage is assumed to ensure the preferential uptake of F14512 by cancer cells, strong interaction with DNA and potent inhibition of topoisomerase II (Topo II. The antitumor activity of F14512 in human tumor models is significantly higher than that of other epipodophyllotoxins in spite of a lower induction of DNA breakage. Hence, the demonstrated superiority of F14512 over other Topo II poisons might not result solely from its preferential uptake by cancer cells, but could also be due to unique effects on Topo II interactions with DNA. To further dissect the mechanism of action of F14512, we used Drosophila melanogaster mutants whose genetic background leads to an easily scored phenotype that is sensitive to changes in Topo II activity and/or localization. F14512 has antiproliferative properties in Drosophila cells and stabilizes ternary Topo II/DNA cleavable complexes at unique sites located in moderately repeated sequences, suggesting that the drug specifically targets a select and limited subset of genomic sequences. Feeding F14512 to developing mutant Drosophila larvae led to the recovery of flies expressing a striking phenotype, "Eye wide shut," where one eye is replaced by a first thoracic segment. Other recovered F14512-induced gain- and loss-of-function phenotypes similarly correspond to precise genetic dysfunctions. These complex in vivo results obtained in a whole developing organism can be reconciled with known genetic anomalies and constitute a remarkable instance of specific alterations of gene expression by ingestion of a drug. "Drosophila-based anticancer pharmacology" hence reveals unique properties for F14512, demonstrating the usefulness of an assay system that provides a low-cost, rapid and effective complement to mammalian models and permits the elucidation of fundamental mechanisms of

  7. Universal properties of materials with the Dirac dispersion relation of low-energy excitations

    Energy Technology Data Exchange (ETDEWEB)

    Protogenov, A. P., E-mail: alprot@appl.sci-nnov.ru [Russian Academy of Sciences, Institute for Applied Physics (Russian Federation); Chulkov, E. V. [Universidad del Pais Vasco, Departamento de Fisica de Materiales (Spain)

    2015-12-15

    The N-terminal scheme is considered for studying the contribution of edge states to the response of a two-dimensional topological insulator. A universal distribution of the nonlocal resistance between terminals is determined in the ballistic transport approach. The calculated responses are identical to experimentally observed values. The spectral properties of surface electronic states in Weyl semimetals are also studied. The density of surface states is accurately determined. The universal behavior of these characteristics is a distinctive feature of the considered Dirac materials which can be used in practical applications.

  8. Universal properties of materials with the Dirac dispersion relation of low-energy excitations

    International Nuclear Information System (INIS)

    Protogenov, A. P.; Chulkov, E. V.

    2015-01-01

    The N-terminal scheme is considered for studying the contribution of edge states to the response of a two-dimensional topological insulator. A universal distribution of the nonlocal resistance between terminals is determined in the ballistic transport approach. The calculated responses are identical to experimentally observed values. The spectral properties of surface electronic states in Weyl semimetals are also studied. The density of surface states is accurately determined. The universal behavior of these characteristics is a distinctive feature of the considered Dirac materials which can be used in practical applications

  9. DTA and DSC study on the effect of mechanical dispersion on poly(tetrafluorethylene properties

    Directory of Open Access Journals (Sweden)

    Dumitraşa Mihai

    2014-12-01

    Full Text Available Poly(tetrafluorethylene particles were obtained by mechanical processing of the formed polymer (Teflon bar. In order to assess the effect of mechanical wear on polymer properties, their melting and crystallization behaviour was investigated by DSC and DTA, and the results were compared to the ones obtained for the native polymer. An increase of the crystallinity degree and an accentuated decrease of the average molecular weight were found for the samples submitted to mechanical wear, as a result of mechanical degradation of the polymer

  10. Properties of B4C–PbO–Al(OH)3-epoxy nanocomposite prepared by ultrasonic dispersion approach for high temperature neutron shields

    International Nuclear Information System (INIS)

    Lee, M.K.; Lee, J.K.; Kim, J.W.; Lee, G.J.

    2014-01-01

    High functional epoxy nanocomposites with three different filler materials, i.e., B 4 C, PbO, and Al(OH) 3 , were fabricated using an effective fabrication method consisting of an ultrasonic dispersion of nanoparticles in low-viscosity hardener and a subsequent mixing of a hardener-nanoparticle colloid with epoxy resins. It was confirmed that this approach provided not only an uniform dispersion but also an excellent wetting with enhanced interfacial adhesion of nano-particulate fillers within the matrix. By incorporating those three fillers, a synergistic effect was verified in multiple properties such as mechanical strength properties, thermal degradation, flame retardancy, and radiation shielding performance

  11. Mechanical properties of Mo-Si-B alloys fabricated by using core-shell powder with dispersion of yttria nanoparticles

    Science.gov (United States)

    Byun, Jong Min; Bang, Su-Ryong; Choi, Won June; Kim, Min Sang; Noh, Goo Won; Kim, Young Do

    2017-01-01

    In recent years, refractory materials with excellent high-temperature properties have been in the spotlight as a next generation's high-temperature materials. Among these, Mo-Si-B alloys composed of two intermetallic compound phases (Mo5SiB2 and Mo3Si) and a ductile α-Mo phase have shown an outstanding thermal properties. However, due to the brittleness of the intermetallic compound phases, Mo-Si-B alloys were restricted to apply for the structural materials. So, to enhance the mechanical properties of Mo-Si-B alloys, many efforts to add rare-earth oxide particles in the Mo-Si-B alloy were performed to induce the improvement of strength and fracture toughness. In this study, to investigate the effect of adding nano-sized Y2O3 particles in Mo-Si-B alloy, a core-shell powder consisting of intermetallic compound phases as the core and nano-sized α-Mo and Y2O3 particles surrounding the core was fabricated. Then pressureless sintering was carried out at 1400 °C for 3 h, and the mechanical properties of sintered bodies with different amounts of Y2O3 particles were evaluated by Vickers hardness and 3-point bending test. Vickers hardness was improved by dispersed Y2O3 particles in the Mo-Si-B alloy. Especially, Mo-3Si-1B-1.5Y2O3 alloy had the highest value, 589 Hv. The fracture toughness was measured using Mo-3Si-1B-1.5Y2O3 alloy and the value indicated as 13.5 MPa·√m.

  12. Effect of Surface Morphology and Dispersion Media on the Properties of PEDOT:PSS/n-Si Hybrid Solar Cell Containing Functionalized Graphene

    Directory of Open Access Journals (Sweden)

    Pham Van Trinh

    2017-01-01

    Full Text Available We present the results on the effect of surface morphology and dispersion media on the properties of PEDOT:PSS/n-Si hybrid solar cell containing functionalized graphene (Gr. The hybrid solar cells based on SiNWs showed higher power conversion efficiency (PCE compared to the planar based cells due to suppressing the carrier recombination and improving carrier transport efficiency. The PCE of hybrid solar cells could be improved by adding Gr into PEDOT:PSS. Different solvents including deionized (DI water, ethylene glycol (EG, and isopropyl alcohol (IPA were used as media for Gr dispersion. The best performance was obtained for the cell containing Gr dispersed in EG with a measured PCE of 7.33% and nearly 13% and 16% enhancement in comparison with the cells using Gr dispersed in IPA and DI water, respectively. The increase in PCE is attributed to improving the carrier-mobility, electrical conductivity, PEDOT crystallinity, and ordering.

  13. Dispersal, individual movement and spatial ecology a mathematical perspective

    CERN Document Server

    Maini, Philip; Petrovskii, Sergei

    2013-01-01

    Dispersal of plants and animals is one of the most fascinating subjects in ecology. It has long been recognized as an important factor affecting ecosystem dynamics. Dispersal is apparently a phenomenon of biological origin; however, because of its complexity, it cannot be studied comprehensively by biological methods alone. Deeper insights into dispersal properties and implications require interdisciplinary approaches involving biologists, ecologists and mathematicians. The purpose of this book is to provide a forum for researches with different backgrounds and expertise and to ensure further advances in the study of dispersal and spatial ecology. This book is unique in its attempt to give an overview of dispersal studies across different spatial scales, such as the scale of individual movement, the population scale and the scale of communities and ecosystems. It is written by top-level experts in the field of dispersal modeling and covers a wide range of problems ranging from the identification of Levy walks...

  14. Enhanced thermoelectric properties of nano SiC dispersed Bi2Sr2Co2Oy Ceramics

    Science.gov (United States)

    Hu, Qiujun; Wang, Kunlun; Zhang, Yingjiu; Li, Xinjian; Song, Hongzhang

    2018-04-01

    The thermoelectric properties of Bi2Sr2Co2Oy + x wt% nano SiC (x = 0.00, 0.025, 0.05, 0.1, 0.2, and 0.3) prepared by the solid-state reaction method were investigated from 300 K to 923 K. The resistivity can be reduced effectively by adding a small amount of SiC nano particles, which is attributed to the increase of the carrier concentration. At the same time, the Seebeck coefficients can be improved effectively due to the energy filtering effect that low energy carriers are strongly dispersed at the interface between the SiC nano particles and the matrix. The decrease of thermal conductivity is due to the increase of the scattering ability of the phonons by the SiC nanoparticles distributed at the boundary of the matrix. As a result, the Bi2Sr2Co2Oy + x wt% SiC composites exhibit better thermoelectric properties. The maximum ZT value 0.24 is obtained when x = 0.05 at 923 K. Compared with the sample without SiC nano particles, the ZT value is increased by about 59.7%.

  15. Multiwalled carbon nanotubes and dispersed nanodiamond novel hybrids: Microscopic structure evolution, physical properties, and radiation resilience

    International Nuclear Information System (INIS)

    Gupta, S.; Farmer, J.

    2011-01-01

    We report the structure and physical properties of novel hybrids of multiwalled carbon nanotubes (MWCNTs) and ultradispersed diamond (UDD) forming nanocomposite ensemble that were subjected to 50, 100, and 10 3 kGy gamma ray doses and characterized using various analytical tools to investigate hierarchical defects evolution. This work is prompted by recent work on single-walled CNTs and UDD ensemble [Gupta et al., J. Appl. Phys. 107, 104308 (2010)] where radiation-induced microscopic defects seem to be stabilized by UDD. The present experiments show similar effects where these hybrids display only a minimal structural modification under the maximum dose. Quantitative analyses of multiwavelength Raman spectra revealed lattice defects induced by irradiation assessed through the variation in prominent D, G, and 2D bands. A minimal change in the position of D, G, and 2D bands and a marginal increase in intensity of the defect-induced double resonant Raman scattered D and 2D bands are some of the implications suggesting the radiation coupling. The in-plane correlation length (L a ) was also determined following Tunistra-Koenig relation from the ratio of D to G band (I D /I G ) besides microscopic stress. However, we also suggest the following taking into account of intrinsic defects of the constituents: (a) charge transfer arising at the interface due to the difference in electronegativity of MWCNT C sp 2 and UDD core (C sp 3 ) leading to phonon and electron energy renormalization; (b) misorientation of C sp 2 at the interface of MWCNT and UDD shell (C sp 2 ) resulting in structural disorder; (c) softening or violation of the q∼0 selection rule leading to D band broadening and a minimal change in G band intensity; and (d) normalized intensity of D and G bands with 2D band help to distinguish defect-induced double resonance phenomena. The MWCNT when combined with nanodiamond showed a slight decrease in their conductance further affected by irradiation pointing at

  16. Preparation and dispersive properties of Ag colloid by electrical explosion of wire

    International Nuclear Information System (INIS)

    Yun, G.S.; Bac, L.H.; Kim, J.S.; Kwon, Y.S.; Choi, H.S.; Kim, J.C.

    2011-01-01

    Research highlights: → Wire diameter and synthetic temperature affect on properties of Ag colloid by EEW. → The lower temperature and smaller diameter make smaller size and narrower size distribution. → Ag colloid are more stable at lower synthetic temperature and smaller size. - Abstract: In this work, Ag colloid was prepared by electrical explosion of wire in deionized water with 0.2 mm and 0.3 mm wire diameter. The temperature of water used for medium of explosion process was change from 20 deg. C to 80 deg. C. Morphology and particle size of nanoparticles was observed by transmission electron microscope. The particle size and size distribution of nanoparticles was found to shift to a smaller size with a decrease of temperature and smaller wire diameter. Surface plasmon resonance of the silver colloids was studied by UV-vis spectroscopy. Stability of silver colloids was investigated by zeta-potential and Turbiscan techniques. The results indicated that temperature of medium during explosion affects much on the stability of Ag colloid. The silver colloidal stability prepared at lower temperature and smaller wire diameter was more stable.

  17. Oxide dispersion strengthened ferritic alloys. 14/20% chromium: effects of processing on deformation texture, recrystallization and tensile properties

    International Nuclear Information System (INIS)

    Regle, H.

    1994-01-01

    The ferritic oxide dispersion strengthened alloys are promising candidates for high temperature application materials, in particular for long life core components of advanced nuclear reactors. The aim of this work is to control the microstructure, in order to optimise the mechanical properties. The two ferritic alloys examined here, MA956 and MA957, are obtained by Mechanical Alloying techniques. They are characterised by quite anisotropic microstructure and mechanical properties. We have investigated the influence of hot and cold working processes (hot extrusion, swaging and cold-drawing) and recrystallization heat treatments on deformation textures, microstructures and tensile properties. The aim was to control the size of the grains and their anisotropic shape, using recrystallization heat treatments. After consolidation and hot extrusion, as-received materials present a extremely fine microstructure with elongated grains and a very strong (110) deformation texture with single-crystal character. At that stage of processing, recrystallization temperature are very high (1450 degrees C for MA957 alloy and 1350 degrees C for MA956 alloy) and materials develop millimetric recrystallized grains. Additional hot extrusion induce a fibre texture. Cold-drawing maintains a fibre texture, but the intensity decreases with increasing cold-work level. For both materials, the decrease of texture intensities correspond to a decrease of the recrystallization temperatures (from 1350 degrees C for a low cold-work level to 750 degrees C for 60 % cold-deformation, case of MA956 alloy) and a refinement of the grain size (from a millimetric size to less than an hundred of micrometer). Swaging develop a cyclic component where the intensity increases with increasing deformation in this case, the recrystallization temperature remains always very high and the millimetric grain size is slightly modified, even though cold-work level increases. Technologically, cold-drawing is the only way

  18. Two-photon fluorescent polysiloxane-based films with thermally responsive self switching properties achieved by a unique reversible spirocyclization mechanism.

    Science.gov (United States)

    Zuo, Yujing; Yang, Tingxin; Zhang, Yu; Gou, Zhiming; Tian, Minggang; Kong, Xiuqi; Lin, Weiying

    2018-03-14

    Responsiveness and reversibility are present in nature, and are ubiquitous in biological systems. The realization of reversibility and responsiveness is of great importance in the development of properties and the design of new materials. However, two-photon fluorescent thermal-responsive materials have not been reported to date. Herein, we engineered thermally responsive polysiloxane materials ( Dns-non ) that exhibited unique two-photon luminescence, and this is the first report about thermally responsive luminescent materials with two-photon fluorescence. The fluorescence of Dns-non could switch from the "on" to "off" state through a facile heating and cooling process, which could be observed by the naked eye. Monitoring the temperature of the CPU in situ was achieved by easily coating D1-non onto the CPU surface, which verified the potential application in devices of Dns-non . A unique alkaline tuned reversible transition mechanism of rhodamine-B from its spirocyclic to its ring-open state was proposed. Furthermore, Dns-non appeared to be a useful cell adhesive for the culture of cells on the surface. We believe that the constructed thermally responsive silicon films which have promising utilization as a new type of functional fluorescent material, may show broad applications in materials chemistry or bioscience.

  19. Effect of Li Adsorption on the Electronic and Hydrogen Storage Properties of Acenes: A Dispersion-Corrected TAO-DFT Study

    OpenAIRE

    Seenithurai, Sonai; Chai, Jeng-Da

    2016-01-01

    Due to the presence of strong static correlation effects and noncovalent interactions, accurate prediction of the electronic and hydrogen storage properties of Li-adsorbed acenes with n linearly fused benzene rings (n = 3 - 8) has been very challenging for conventional electronic structure methods. To meet the challenge, we study these properties using our recently developed thermally-assisted-occupation density functional theory (TAO-DFT) with dispersion corrections. In contrast to pure acen...

  20. One-pot synthesis of biocompatible Te-phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process

    International Nuclear Information System (INIS)

    Qian Haisheng; Zhu Enbo; Zheng Shunji; Yang Xingyun; Li Liangchao; Tong Guoxiu; Li Zhengquan; Hu Yong; Guo Changfa; Guo Huichen

    2010-01-01

    One-pot hydrothermal process has been developed to synthesize uniform Te-phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te-phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

  1. One-pot synthesis of biocompatible Te@phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process.

    Science.gov (United States)

    Qian, Haisheng; Zhu, Enbo; Zheng, Shunji; Li, Zhengquan; Hu, Yong; Guo, Changfa; Yang, Xingyun; Li, Liangchao; Tong, Guoxiu; Guo, Huichen

    2010-12-10

    One-pot hydrothermal process has been developed to synthesize uniform Te@phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te@phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

  2. One-pot synthesis of biocompatible Te-phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process

    Energy Technology Data Exchange (ETDEWEB)

    Qian Haisheng; Zhu Enbo; Zheng Shunji; Yang Xingyun; Li Liangchao; Tong Guoxiu [Department of Chemistry, College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004 (China); Li Zhengquan; Hu Yong; Guo Changfa [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Guo Huichen, E-mail: shqian@zjnu.cn, E-mail: ghch-2004@hotmail.com [State Key Laboratory of Veterinary Etiological Biology and Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 11, Lanzhou, Gansu 730046 (China)

    2010-12-10

    One-pot hydrothermal process has been developed to synthesize uniform Te-phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te-phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

  3. Solid-state characterization and dissolution properties of meloxicam-moringa coagulant-PVP ternary solid dispersions.

    Science.gov (United States)

    Noolkar, Suhail B; Jadhav, Namdeo R; Bhende, Santosh A; Killedar, Suresh G

    2013-06-01

    The effect of ternary solid dispersions of poor water-soluble NSAID meloxicam with moringa coagulant (obtained by salt extraction of moringa seeds) and polyvinylpyrrolidone on the in vitro dissolution properties has been investigated. Binary (meloxicam-moringa and meloxicam-polyvinylpyrrolidone (PVP)) and ternary (meloxicam-moringa-PVP) systems were prepared by physical kneading and ball milling and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffractometry. The in vitro dissolution behavior of meloxicam from the different products was evaluated by means of United States Pharmacopeia type II dissolution apparatus. The results of solid-state studies indicated the presence of strong interactions between meloxicam, moringa, and PVP which were of totally amorphous nature. All ternary combinations were significantly more effective than the corresponding binary systems in improving the dissolution rate of meloxicam. The best performance in this respect was given by the ternary combination employing meloxicam-moringa-PVP ratio of [1:(3:1)] prepared by ball milling, with about six times increase in percent dissolution rate, whereas meloxicam-moringa (1:3) and meloxicam-PVP (1:4) prepared by ball milling improved dissolution of meloxicam by almost 3- and 2.5-folds, respectively. The achieved excellent dissolution enhancement of meloxicam in the ternary systems was attributed to the combined effects of impartation of hydrophilic characteristic by PVP, as well as to the synergistic interaction between moringa and PVP.

  4. Microstructure and Mechanical Properties of Nano-Size Zirconium Carbide Dispersion Strengthened Tungsten Alloys Fabricated by Spark Plasma Sintering Method

    International Nuclear Information System (INIS)

    Xie Zhuoming; Liu Rui; Fang Qianfeng; Zhang Tao; Jiang Yan; Wang Xianping; Liu Changsong

    2015-01-01

    W-(0.2, 0.5, 1.0)wt% ZrC alloys with a relative density above 97.5% were fabricated through the spark plasma sintering (SPS) method. The grain size of W-1.0wt% ZrC is about 2.7 μm, smaller than that of pure W and W-(0.2, 0.5)wt% ZrC. The results indicated that the W-ZrC alloys exhibit higher hardness at room temperature, higher tensile strength at high temperature, and a lower ductile to brittle transition temperature (DBTT) than pure W. The tensile strength and total elongation of W-0.5wt% ZrC alloy at 700 °C is 535 MPa and 24.8%, which are respectively 59% and 114% higher than those of pure W (337 MPa, 11.6%). The DBTT of W-(0.2, 0.5, 1.0)wt% ZrC materials is in the range of 500°C–600°C, which is about 100 °C lower than that of pure W. Based on microstructure analysis, the improved mechanical properties of the W-ZrC alloys were suggested to originate from the enhanced grain boundary cohesion by ZrC capturing the impurity oxygen in tungsten and nano-size ZrC dispersion strengthening. (paper)

  5. Elevated temperature tensile properties of borated 304 stainless steel: Effect of boride dispersion on strength and ductility

    International Nuclear Information System (INIS)

    Stephens, J.J.; Sorenson, K.B.; McConnell, P.

    1991-01-01

    This paper has documented the increase in strain to fracture and yield strength obtained with Grade A versions of types 304B5 and 304B7 relative to their respective Grade B, counterparts. The apparent microstructural reason for these property increases is the finer dispersion of boride in the Grade A material, obtained by means of a Powder Metallurgy process, relative to the conventional Grade B material which is produced using an Ingot Metallurgy process. The area size distribution of borides can be well approximated using a log-normal distribution, with the largest boride particles in the Grade B material having areas in the range of 450--600 μm 2 . By comparison, the largest boride particles in the Grade A material have areas nearly an order of magnitude smaller than the largest particles in their Grade B counterparts. A Section III ASME B ampersand PV code case inquiry has been initiated for non-welded versions of 304B4A, 3045A and 3046A ,material

  6. Magnetic properties as tracers for source-to-sink dispersal of sediments: A case study in the Taiwan Strait

    Science.gov (United States)

    Horng, Chorng-Shern; Huh, Chih-An

    2011-09-01

    Different lithologies between Taiwan and southeastern China lead to diverse mineralogical composition for weathering products derived from the two shores of the Taiwan Strait. Pyrrhotite and magnetite are respectively the dominant magnetic minerals associated with fluvial sediments from western Taiwan and southeastern China. While magnetite commonly co-exists with pyrrhotite in sediments sourced from Taiwan, pyrrhotite has not been found in sediments sourced from mainland China. Associated with such a distinction are vast differences in magnetic properties, including magnetic susceptibility (χ), SIRM, HIRM and the S-ratio, which can be used to study the provenances of sediments in the Taiwan Strait and adjoining marginal seas. Based on any two of these parameters, the magnetic characteristics of much of the Taiwan Strait sediment can be explained using a two-endmember mixing model. Source-to-sink dispersal of sediments in the Taiwan Strait can then be traced from the distribution of these parameters. The results not only corroborate an earlier study based on radionuclides and particle size distribution ( Huh et al., 2011) but reveal more diagnostic details. Besides spatial distribution based on a large number (216) of surface sediments, we also analyzed temporal variation of magnetic properties in six well-dated cores collected at key sites along the sediment source-to-sink pathways. From profiles of these parameters in cores from the middle of the northern Taiwan Strait, it is calculated that sediment supply from Taiwan has increased substantially in the past five decades, which may very well be related to accelerated land use and increased frequency of intense rainfalls in Taiwan during the same period. The approach described in this work may be extended to other source-to-sink systems around the world and through time, especially the mountainous islands fringing the Pacific and Indian Oceans in southeastern Asia. As with Taiwan, these islands have high

  7. Using non-invasive molecular spectroscopic techniques to detect unique aspects of protein Amide functional groups and chemical properties of modeled forage from different sourced-origins.

    Science.gov (United States)

    Ji, Cuiying; Zhang, Xuewei; Yu, Peiqiang

    2016-03-05

    The non-invasive molecular spectroscopic technique-FT/IR is capable to detect the molecular structure spectral features that are associated with biological, nutritional and biodegradation functions. However, to date, few researches have been conducted to use these non-invasive molecular spectroscopic techniques to study forage internal protein structures associated with biodegradation and biological functions. The objectives of this study were to detect unique aspects and association of protein Amide functional groups in terms of protein Amide I and II spectral profiles and chemical properties in the alfalfa forage (Medicago sativa L.) from different sourced-origins. In this study, alfalfa hay with two different origins was used as modeled forage for molecular structure and chemical property study. In each forage origin, five to seven sources were analyzed. The molecular spectral profiles were determined using FT/IR non-invasive molecular spectroscopy. The parameters of protein spectral profiles included functional groups of Amide I, Amide II and Amide I to II ratio. The results show that the modeled forage Amide I and Amide II were centered at 1653 cm(-1) and 1545 cm(-1), respectively. The Amide I spectral height and area intensities were from 0.02 to 0.03 and 2.67 to 3.36 AI, respectively. The Amide II spectral height and area intensities were from 0.01 to 0.02 and 0.71 to 0.93 AI, respectively. The Amide I to II spectral peak height and area ratios were from 1.86 to 1.88 and 3.68 to 3.79, respectively. Our results show that the non-invasive molecular spectroscopic techniques are capable to detect forage internal protein structure features which are associated with forage chemical properties. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. A comparative study of the effect of spray drying and hot-melt extrusion on the properties of amorphous solid dispersions containing felodipine.

    Science.gov (United States)

    Mahmah, Osama; Tabbakh, Rami; Kelly, Adrian; Paradkar, Anant

    2014-02-01

    To compare the properties of solid dispersions of felodipine for oral bioavailability enhancement using two different polymers, polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose acetate succinate (HPMCAS), by hot-melt extrusion (HME) and spray drying. Felodipine solid dispersions were prepared by HME and spray drying techniques. PVP and HPMCAS were used as polymer matrices at different drug : polymer ratios (1 : 1, 1 : 2 and 1 : 3). Detailed characterization was performed using differential scanning calorimetry, powder X-ray diffractometry, scanning electron microscopy and in-vitro dissolution testing. Dissolution profiles were evaluated in the presence of sodium dodecyl sulphate. Stability of different solid dispersions was studied under accelerated conditions (40°C/75% RH) over 8 weeks. Spray-dried formulations were found to release felodipine faster than melt extruded formulations for both polymer matrices. Solid dispersions containing HMPCAS exhibited higher drug release rates and better wettability than those produced with a PVP matrix. No significant differences in stability were observed except with HPMCAS at a 1 : 1 ratio, where crystallization was detected in spray-dried formulations. Solid dispersions of felodipine produced by spray drying exhibited more rapid drug release than corresponding melt extruded formulations, although in some cases improved stability was observed for melt extruded formulations. © 2013 Royal Pharmaceutical Society.

  9. Influence of spray drying and dispersing agent on surface and dissolution properties of griseofulvin micro and nanocrystals.

    Science.gov (United States)

    Shah, Dhaval A; Patel, Manan; Murdande, Sharad B; Dave, Rutesh H

    2016-11-01

    The purpose for the current research is to compare and evaluate physiochemical properties of spray-dried (SD) microcrystals (MCs), nanocrystals (NCs), and nanocrystals with a dispersion agent (NCm) from a poorly soluble compound. The characterization was carried out by performing size and surface analysis, interfacial tension (at particle moisture interface), and in-vitro drug dissolution rate experiments. Nanosuspensions were prepared by media milling and were spray-dried. The SD powders that were obtained were characterized morphologically using scanning electron microscopy (SEM), polarized light microscopy (PLM), and Flowchem. Solid-state characterization was performed using X-ray powder diffraction (XRPD), Fourier transfer infrared spectroscopy (FT-IR), and differential scanning calorimetry (DSC) for the identification of the crystalline nature of all the SD powders. The powders were characterized for their redispersion tendency in the water and in pH 1.2. Significant differences in redispersion were noted for both the NCs in both dissolution media. The interfacial tension for particle moisture interface was determined by applying the BET (Braunauer-Emmett-Teller) equation to the vapor sorption data. No significant reduction in the interfacial tension was observed between MCs and NCs; however, a significant reduction in the interfacial tension was observed for NCm at both 25 °C and 35 °C temperatures. The difference in interfacial tension and redispersion behavior can be attributed to a difference in the wetting tendency for all the SD powders. The dissolution studies were carried out under sink and under non-sink conditions. The non-sink dissolution approach was found suitable for quantification of the dissolution rate enhancement, and also for providing the rank order to the SD formulations.

  10. Material properties of oxide dispersion strengthened (ODS) ferritic steels for core materials of FBR. Mechanical strength properties of sodium exposed and Nickel diffused materials. Interim report

    International Nuclear Information System (INIS)

    Kato, Shoichi; Yoshida, Eiichi

    2004-02-01

    An oxide dispersion strengthened (ODS) ferritic steel have excellent resistance to swelling and superior creep strength, they are expected to be used as a long-life cladding material in future advanced fast reactor. In this study, sodium environmental effects on the ODS steel developed by JNC were clarified through tensile test after sodium exposure for maximum 10,000hrs and creep-rupture test in sodium at elevated temperature. The exposure to sodium was conducted using a sodium test loop constituted by austenitic steels. For the conditions of sodium exposure test, the sodium temperatures were 923 K and 973 K, the oxygen concentration in sodium was below 2ppm and sodium flow rate on the surface of specimen was less than 1x10 -4 m/s. Further the specimen with the nickel diffused was prepared, which is simulate to nickel diffusing through sodium from the surface of structural stainless steels. The main results obtained were as follows; (1) The results showed excellent sodium-resistance up to a high temperature of about 973 K in stagnant sodium conditions, and its considered that the effects of sodium environment of tensile properties were negligible. In case of stagnant sodium condition, creep-rupture strength in sodium was equal to the in argon gas, and no sodium environmental effect was observed. The same is true for the creep-rupture ductility. (2) The tensile properties of nickel diffused test specimens at high temperatures simulating microstructure change were equal to that of the thermal aging process specimens. These tensile tests suggest that sodium environmental effects can be ignored. However, the effect of nickel diffusion on creep strength are not clear at present and experimental investigation are being conducted. (3) The coefficient of nickel diffusion in the ODS steel can be estimated based on the results of nickel concentration measurement. This value is larger than that of the diffusion coefficient for typical α-Fe steel at temperature below 973 K

  11. Material properties of oxide dispersion strengthened (ODS) ferritic steels for core materials of FBR. Tensile properties of sodium exposed and nickel diffused materials

    International Nuclear Information System (INIS)

    Kato, Shoichi; Yoshida, Eiichi

    2002-12-01

    An oxide dispersion strengthened (ODS) ferritic steel is candidate for a long-life core materials of future FBR, because of good swelling resistance and high creep strength. In this study, tensile tests were carried out the long-term extrapolation of sodium environmental effects on the mechanical properties of ODS steels. The tested heats of materials are M93, M11 and F95. The specimens were pre-exposed to sodium for 1,000 and 3,000 hours under non-stress conditions. The pre-exposure to sodium was conducted using a sodium test loop constituted by austenitic steels. For the conditions of sodium exposure test, the sodium temperature was 650 and 700degC, the oxygen concentration in sodium was about 1 ppm and sodium flow rate on the surface of specimen was less than 1x10 -4 m/seconds (nearly static). Further the specimen with the nickel diffused was prepared, which is simulate to nickel diffusing through sodium from the surface of structural stainless steels. The main results obtained were as follows; (1) The tensile strength and the fracture elongation after sodium exposure (maximum 3,000 hours) were same as that of as-received materials. If was considered that the sodium environmental effect is negligible under the condition of this study. (2) Tensile properties of nickel diffused specimens were slightly lower than that of the as-received specimens, but it remains equal to that of thermal aging specimens. (3) The change in microstructure such as a degraded layer was observed on the surface of nickel diffused specimen. In the region of the degraded layer, phase transformations from the α-phase to the γ-phase were recognized. But, the microscopic oxide particles were observed same as that of α-phase base metal. (author)

  12. Carbon nanotube modification using gum arabic and its effect on the dispersion and tensile properties of carbon nanotubes/epoxy nanocomposites.

    Science.gov (United States)

    Kim, Man Tae; Park, Ho Seok; Hui, David; Rhee, Kyong Yop

    2011-08-01

    In this study, the effects of a MWCNT treatment on the dispersion of MWCNTs in aqueous solution and the tensile properties of MWCNT/epoxy nanocomposites were investigated. MWCNTs were treated using acid and gum arabic, and MWCNT/epoxy nanocomposites were fabricated with 0.3 wt.% unmodified, oxidized and gum-treated MWCNTs. The dispersion states of the unmodified, oxidized, and Gum-treated MWCNTs were characterized in distilled water. The tensile strengths and elastic modulus of the three nanocomposites were determined and compared. The results indicated that the gum treatment produced better dispersion of the MWCNTs in distilled water and that gum-treated MWCNT/epoxy nanocomposites had a better tensile strength and elastic modulus than did the unmodified and acid-treated MWCNT/epoxy nanocomposites. Scanning electron microscope examination of the fracture surface showed that the improved tensile properties of the gum-treated MWCNT/epoxy nanocomposites were attributed to the improved dispersion of MWCNTs in the epoxy and to interfacial bonding between nanotubes and the epoxy matrix.

  13. Hydrothermal Synthesis of Highly Water-dispersible Anatase Nanoparticles with Large Specific Surface Area and Their Adsorptive Properties

    Directory of Open Access Journals (Sweden)

    Hu Xueting

    2016-01-01

    Full Text Available Highly water-dispersible and very small TiO2 nanoparticles (~3 nm anatase with large specific surface area have been synthesized by hydrolysis and hydrothermal reactions of titanium butoxide and used for the removal of three azo dyes (Congo red, orange II, and methyl orange with different molecular structure from simulated wastewaters. The synthesized TiO2 nanoparticles are well dispersed in water with large specific surface area up to 417 m2 g−1. Adsorption experiments demonstrated that the water-dispersible TiO2 nanoparticles possess excellent adsorption capacities for Congo red, orange II, and methyl orange, which could be attributed to their good water-dispersibility and large specific surface area.

  14. Hydrothermal Synthesis of Highly Water-dispersible Anatase Nanoparticles with Large Specific Surface Area and Their Adsorptive Properties

    OpenAIRE

    Hu Xueting; Zhang Dongyun; Zhao Siqin; Asuha Sin

    2016-01-01

    Highly water-dispersible and very small TiO2 nanoparticles (~3 nm anatase) with large specific surface area have been synthesized by hydrolysis and hydrothermal reactions of titanium butoxide and used for the removal of three azo dyes (Congo red, orange II, and methyl orange) with different molecular structure from simulated wastewaters. The synthesized TiO2 nanoparticles are well dispersed in water with large specific surface area up to 417 m2 g−1. Adsorption experiments demonstrated that th...

  15. Characterization of Thermo-Elastic Properties and Microcracking Behaviors of CFRP Laminates Using Cup-Stacked Carbon Nanotubes (CSCNT) Dispersed Resin

    Science.gov (United States)

    Yokozeki, Tomohiro; Iwahori, Yutaka; Ishiwata, Shin

    This study investigated the thermo-elastic properties and microscopic ply cracking behaviors in carbon fiber reinforced nanotube-dispersed epoxy laminates. The nanocomposite laminates used in this study consisted of traditional carbon fibers and epoxy resin filled with cup-stacked carbon nanotubes (CSCNTs). Thermo-mechanical properties of unidirectional nanocomposite laminates were evaluated, and quasi-static and fatigue tension tests of cross-ply laminates were carried out in order to observe the damage accumulation behaviors of matrix cracks. Clear retardation of matrix crack onset and accumulation was found in composite laminates with CSCNT compared to those without CSCNT. Fracture toughness associated with matrix cracking was evaluated based on the analytical model using the experimental results. It was concluded that the dispersion of CSCNT resulted in fracture toughness improvement and residual thermal strain decrease, and specifically, the former was the main contribution to the retardation of matrix crack formation.

  16. The Effect of Dispersion Phases of SiC and Al2O3 on the Properties of Galvanic Nickel Coatings

    Directory of Open Access Journals (Sweden)

    Kozik A.

    2016-03-01

    Full Text Available In this study, Ni, Ni-SiC and Ni-Al2O3 coatings were electroplated on the 2xxx series aluminium alloy. The following parameters of the electroplating process were applied: current density - 4A/dm2, time - 60 minutes, and temperature - 60°C. Hard particles of submicrometric size were used. The results of the research showing the effect of the addition of hard particles (introduced into the nickel bath as a dispersed phase on the properties of coatings, including the effect of the type (SiC or Al2O3 and content (0, 25, 50 g / l of these particles, were discussed. Based on extensive investigations, it was found that the type of ceramic particles significantly affects the structure of produced coatings. The dispersed particles incorporated into the nickel coatings improve their abrasion resistance. Improving of the corrosion properties were observed only in the case of coatings containing silicon carbide particles.

  17. From linking of metal-oxide building blocks in a dynamic library to giant clusters with unique properties and towards adaptive chemistry.

    Science.gov (United States)

    Müller, Achim; Gouzerh, Pierre

    2012-11-21

    Following Nature's lessons, today chemists can cross the boundary of the small molecule world to construct multifunctional and highly complex molecular nano-objects up to protein size and even cell-like nanosystems showing responsive sensing. Impressive examples emerge from studies of the solutions of some oxoanions of the early transition metals especially under reducing conditions which enable the controlled linking of metal-oxide building blocks. The latter are available from constitutional dynamic libraries, thus providing the option to generate multifunctional unique nanoscale molecular systems with exquisite architectures, which even opens the way towards adaptive and evolutive (Darwinian) chemistry. The present review presents the first comprehensive report of current knowledge (including synthesis aspects not discussed before) regarding the related giant metal-oxide clusters mainly of the type {Mo(57)M'(6)} (M' = Fe(III), V(IV)) (torus structure), {M(72)M'(30)} (M = Mo, M' = V(IV), Cr(III), Fe(III), Mo(V)), {M(72)Mo(60)} (M = Mo, W) (Keplerates), {Mo(154)}, {Mo(176)}, {Mo(248)} ("big wheels"), and {Mo(368)} ("blue lemon") - all having the important transferable pentagonal {(M)M(5)} groups in common. These discoveries expanded the frontiers of inorganic chemistry to the mesoscopic world, while there is probably no collection of discrete inorganic compounds which offers such a versatile chemistry and the option to study new phenomena of interdisciplinary interest. The variety of different properties of the sphere- and wheel-type metal-oxide-based clusters can directly be related to their unique architectures: The spherical Keplerate-type capsules having 20 crown-ether-type pores and tunable internal functionalities allow the investigation of confined matter as well as that of sphere-surface-supramolecular and encapsulation chemistry - including related new aspects of the biologically important hydrophobic effects - but also of nanoscale ion transport and

  18. Amorphization of thiamine chloride hydrochloride: A study of the crystallization inhibitor properties of different polymers in thiamine chloride hydrochloride amorphous solid dispersions.

    Science.gov (United States)

    Arioglu-Tuncil, Seda; Bhardwaj, Vivekanand; Taylor, Lynne S; Mauer, Lisa J

    2017-09-01

    Amorphous solid dispersions of thiamine chloride hydrochloride (THCl) were created using a variety of polymers with different physicochemical properties in order to investigate how effective the various polymers were as THCl crystallization inhibitors. THCl:polymer dispersions were prepared by lyophilizing solutions of THCl and amorphous polymers (guar gum, pectin, κ-carrageenan, gelatin, and polyvinylpyrrolidone (PVP)). These dispersions were stored at select temperature (25 and 40°C) and relative humidity (0, 23, 32, 54, 75, and 85% RH) conditions and monitored at different time points using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Moisture sorption isotherms of all samples were also obtained. Initially amorphous THCl was produced in the presence of ≥40% w/w pectin, κ-carrageenan, gelatin, and guar gum or ≥60% w/w PVP. Trends in polymer THCl crystallization inhibition (pectin≥κ-carrageenan>gelatin>guar gum≫PVP) were primarily based on the ability of the polymer to interact with THCl via hydrogen bonding and/or ionic interactions. The onset of THCl crystallization from the amorphous dispersions was also related to storage conditions. THCl remained amorphous at low RH conditions (0 and 23% RH) in all 1:1 dispersions except THCl:PVP. THCl crystallized in some dispersions below the glass transition temperature (T g ) but remained amorphous in others at T~T g . At high RHs (75 and 85% RH), THCl crystallized within one day in all samples. Given the ease of THCl amorphization in the presence of a variety of polymers, even at higher vitamin concentrations than would be found in foods, it is likely that THCl is amorphous in many low moisture foods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Preparation and properties of high storage stability polyester polyol dispersion for two-component waterborne polyurethane coating

    Science.gov (United States)

    Hao, H.; Hu, J. Q.; Wang, F.; Tu, W. P.

    2017-01-01

    A new type of polyester polyol dispersion with good storage stability was prepared based on a hydrophilic monomer 5-sodium sulfodimethyl isophthalate (5-SIPM), and frequently-used monomers such as neopentyl glycol (NPG), dimethyl terephthalate (DMT), dimethyl phthalate (DMP) and trimethylolpropane (TMP) by the transpolycondensation and polycondensation method. The polyester polyol dispersion was characterized by FTIR and GPC. The proper content of these monomers were determined by the performance of polyester dispersion: the content of TMP was 15wt%, the content of NPG was 7.5wt% and the hydrophilic monomer 5-SIPM content was 5wt%. Two-component waterborne polyurethane (2K-WPU) coatings were prepared by Bayhydur® XP2487/1 and polyester polyol dispersions, which were stored before and after at 40 ° for 6 weeks, the prepared films have no differences in drying time, adhesion, pencil hardness, gloss and chemical resistance, the result also reveals that the polyester polyol dispersion have excellent storage stability resistance.

  20. Controllable Absorption and Dispersion Properties of an RF-driven Five-Level Atom in a Double-Band Photonic-Band-Gap Material

    International Nuclear Information System (INIS)

    Ding Chunling; Li Jiahua; Yang Xiaoxue

    2011-01-01

    The probe absorption-dispersion spectra of a radio-frequency (RF)-driven five-level atom embedded in a photonic crystal are investigated by considering the isotropic double-band photonic-band-gap (PBG) reservoir. In the model used, the two transitions are, respectively, coupled by the upper and lower bands in such a PBG material, thus leading to some curious phenomena. Numerical simulations are performed for the optical spectra. It is found that when one transition frequency is inside the band gap and the other is outside the gap, there emerge three peaks in the absorption spectra. However, for the case that two transition frequencies lie inside or outside the band gap, the spectra display four absorption profiles. Especially, there appear two sharp peaks in the spectra when both transition frequencies exist inside the band gap. The influences of the intensity and frequency of the RF-driven field on the absorptive and dispersive response are analyzed under different band-edge positions. It is found that a transparency window appears in the absorption spectra and is accompanied by a very steep variation of the dispersion profile by adjusting system parameters. These results show that the absorption-dispersion properties of the system depend strongly on the RF-induced quantum interference and the density of states (DOS) of the PBG reservoir. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  1. Agglomerate properties and dispersibility changes of salmeterol xinafoate from powders for inhalation after storage at high relative humidity.

    Science.gov (United States)

    Das, Shyamal; Larson, Ian; Young, Paul; Stewart, Peter

    2009-06-28

    This study investigated changes in agglomeration and the mechanism of dispersibility decrease of salmeterol xinafoate (SX) from SX-lactose mixtures for inhalation after storage at 75% RH for 3 months. The dispersibility, PSD and in situ PSD of aerosol plumes of SX alone and SX-coarse lactose (CL) mixtures containing 0, 5, 10 and 20% micronized lactose (ML) before and after storage were determined by a Next Generation Impactor (NGI), a Mastersizer 2000 and a Spraytec, respectively. The PSD of ML increased after storage at 75% RH, but dispersibility of SX using the stored ML increased. After storage, the %SX of the mixture containing 20% ML (M20F) significantly increased (Pagglomerates, probably occurring through enhanced capillary interaction and/or solid bridging of ML, entrapping and preventing the release of SX particles.

  2. Comparative Study on Dispersion and Interfacial Properties of Single Walled Carbon Nanotube/Polymer Composites Using Hansen Solubility Parameters

    DEFF Research Database (Denmark)

    Ma, Jing; Larsen, Mikael

    2013-01-01

    fabricated by solution blending 1 wt % SWNTs with various modification (nonmodified, nitric acid functionalized, and amine functionalized SWNTs) and three kinds of polymeric materials (polycarbonate, polyvinylidene fluoride, and epoxy). Chemical compatibilities between SWNTs and solvents or polymers...... are calculated by the Hansen solubility parameters (HSP) method. The dispersion of the SWNTs in solvents is evaluated by dynamic light scattering. The dispersion of SWNTs in polymers evaluated by a light optical microscope (LOM) generally agrees with the HSP prediction. The strain transfer from the matrix...

  3. A highly selective dispersive liquid-liquid microextraction approach based on the unique fluorous affinity for the extraction and detection of per- and polyfluoroalkyl substances coupled with high performance liquid chromatography tandem-mass spectrometry.

    Science.gov (United States)

    Wang, Juan; Shi, Yali; Cai, Yaqi

    2018-04-06

    In the present study, a highly selective fluorous affinity-based dispersive liquid-liquid microextraction (DLLME) technique was developed for the extraction and analysis of per- and polyfluoroalkyl substances (PFASs) followed by high performance liquid chromatography tandem-mass spectrometry. Perfluoro-tert-butanol with multiple C-F bonds was chosen as the extraction solvent, which was injected into the aqueous samples with a dispersive solvent (acetonitrile) in a 120:800 (μL, v/v) mixture for PFASs enrichment. The fluorous affinity-based extraction mechanism was confirmed by the significantly higher extraction recoveries for PFASs containing multiple fluorine atoms than those for compounds with fewer or no fluorine atoms. The extraction recoveries of medium and long-chain PFASs (CF 2  > 5) exceeded 70%, except perfluoroheptanoic acid, while those of short-chain PFASs were lower than 50%, implying that the proposed DLLME may not be suitable for their extraction due to weak fluorous affinity. This highly fluoroselective DLLME technique can greatly decrease the matrix effect that occurs in mass spectrometry detection when applied to the analysis of urine samples. Under the optimum conditions, the relative recoveries of PFASs with CF 2  > 5 ranged from 80.6-121.4% for tap water, river water and urine samples spiked with concentrations of 10, 50 and 100 ng/L. The method limits of quantification for PFASs in water and urine samples were in the range of 0.6-8.7 ng/L. Furthermore, comparable concentrations of PFASs were obtained via DLLME and solid-phase extraction, confirming that the developed DLLME technique is a promising method for the extraction of PFASs in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Multi-walled carbon nanotube filled polypropylene nanocomposites based on masterbatch route: Improvement of dispersion and mechanical properties through PP-g-MA addition

    Directory of Open Access Journals (Sweden)

    2008-10-01

    Full Text Available Multi-wall carbon nanotubes (MWNTs filled polypropylene (PP nanocomposites were prepared through diluting a PP/MWNT masterbatch in a PP matrix by melt compounding with a twin screw extruder. Polypropylene grafted maleic anhydride (PP-g-MA was used to promote the carbon nanotubes dispersion. The effect of PP-g-MA addition on the rheological, mechanical and morphological properties of the nanocomposites was assessed for different MWNTs loadings. Scanning electron microscopy (SEM has shown that nanotubes are distributed reasonably uniformly. A better dispersion and good adhesion between the nanotubes and the PP matrix is caused by wrapping of PP-g-MA on MWNTs. When PP-g-MA is added, dynamic moduli and viscosity further increases compared to PP/MWNT nanocomposites. The rheological percolation threshold drops significantly. Tensile and flexural moduli and Charpy impact resistance of the nanocomposites also increases by the addition of PP-g-MA. The present study confirms that PP-g-MA is efficient to promote the dispersion of MWNTs in PP matrix and serves as an adhesive to increase their interfacial strength, hence greatly improving the rheological percolation threshold and mechanical properties of PP/MWNT nanocomposites.

  5. Industrial-Graded Epoxy Nanocomposites with Mechanically Dispersed Multi-Walled Carbon Nanotubes: Static and Damping Properties

    Directory of Open Access Journals (Sweden)

    Andrea Giovannelli

    2017-10-01

    Full Text Available The majority of currently published dispersion protocols of carbon nanotubes rely on techniques that are not scalable to an industrial level. This work shows how to obtain polymer nanocomposites with good mechanical characteristics using multi-walled carbon nanotubes epoxy resins obtained by mechanical mixing only. The mechanical dispersion method illustrated in this work is easily scalable to industrial level. The high shearing force due to the complex field of motion produces a good and reproducible carbon nanotube dispersion. We have tested an industrial epoxy matrix with good baseline mechanical characteristics at different carbon nanotube weight loads. ASTM-derived tensile and compressive tests show an increment in both Young’s modulus and compressive strength compared with the pristine resin from a starting low wt %. Comparative vibration tests show improvement in the damping capacity. The new carbon nanotube enhanced epoxy resin has superior mechanical proprieties compared to the market average competitor, and is among the top products in the bi-components epoxy resins market. The new dispersion method shows significant potential for the industrial use of CNTs in epoxy matrices.

  6. Electro-optic and thermo-optic and properties of phase separated polymer dispersed liquid crystal films

    Czech Academy of Sciences Publication Activity Database

    Malik, P.; Bubnov, Alexej M.; Raina, K.K.

    2008-01-01

    Roč. 494, č. 12 (2008), s. 242-251 ISSN 1542-1406 Institutional research plan: CEZ:AV0Z10100520 Keywords : polymer dispersed liquid crystals * electro-optics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.537, year: 2008

  7. Industrial-Graded Epoxy Nanocomposites with Mechanically Dispersed Multi-Walled Carbon Nanotubes: Static and Damping Properties.

    Science.gov (United States)

    Giovannelli, Andrea; Di Maio, Dario; Scarpa, Fabrizio

    2017-10-24

    The majority of currently published dispersion protocols of carbon nanotubes rely on techniques that are not scalable to an industrial level. This work shows how to obtain polymer nanocomposites with good mechanical characteristics using multi-walled carbon nanotubes epoxy resins obtained by mechanical mixing only. The mechanical dispersion method illustrated in this work is easily scalable to industrial level. The high shearing force due to the complex field of motion produces a good and reproducible carbon nanotube dispersion. We have tested an industrial epoxy matrix with good baseline mechanical characteristics at different carbon nanotube weight loads. ASTM-derived tensile and compressive tests show an increment in both Young's modulus and compressive strength compared with the pristine resin from a starting low wt %. Comparative vibration tests show improvement in the damping capacity. The new carbon nanotube enhanced epoxy resin has superior mechanical proprieties compared to the market average competitor, and is among the top products in the bi-components epoxy resins market. The new dispersion method shows significant potential for the industrial use of CNTs in epoxy matrices.

  8. The Theory of Adaptive Dispersion and Acoustic-phonetic Properties of Cross-language Lexical-tone Systems

    Science.gov (United States)

    Alexander, Jennifer Alexandra

    Lexical-tone languages use fundamental frequency (F0/pitch) to convey word meaning. About 41.8% of the world's languages use lexical tone (Maddieson, 2008), yet those systems are under-studied. I aim to increase our understanding of speech-sound inventory organization by extending to tone-systems a model of vowel-system organization, the Theory of Adaptive Dispersion (TAD) (Liljencrants and Lindblom, 1972). This is a cross-language investigation of whether and how the size of a tonal inventory affects (A) acoustic tone-space size and (B) dispersion of tone categories within the tone-space. I compared five languages with very different tone inventories: Cantonese (3 contour, 3 level tones); Mandarin (3 contour, 1 level tone); Thai (2 contour, 3 level tones); Yoruba (3 level tones only); and Igbo (2 level tones only). Six native speakers (3 female) of each language produced 18 CV syllables in isolation, with each of his/her language's tones, six times. I measured tonal F0 across the vowel at onset, midpoint, and offglide. Tone-space size was the F0 difference in semitones (ST) between each language's highest and lowest tones. Tone dispersion was the F0 distance (ST) between two tones shared by multiple languages. Following the TAD, I predicted that languages with larger tone inventories would have larger tone-spaces. Against expectations, tone-space size was fixed across level-tone languages at midpoint and offglide, and across contour-tone languages (except Thai) at offglide. However, within each language type (level-tone vs. contour-tone), languages with smaller tone inventories had larger tone spaces at onset. Tone-dispersion results were also unexpected. The Cantonese mid-level tone was further dispersed from a tonal baseline than the Yoruba mid-level tone; Cantonese mid-level tone dispersion was therefore greater than theoretically necessary. The Cantonese high-level tone was also further dispersed from baseline than the Mandarin high-level tone -- at midpoint

  9. Uniquely Strongly Clean Group Rings

    Institute of Scientific and Technical Information of China (English)

    WANG XIU-LAN

    2012-01-01

    A ring R is called clean if every element is the sum of an idempotent and a unit,and R is called uniquely strongly clean (USC for short) if every element is uniquely the sum of an idempotent and a unit that commute.In this article,some conditions on a ring R and a group G such that RG is clean are given.It is also shown that if G is a locally finite group,then the group ring RG is USC if and only if R is USC,and G is a 2-group.The left uniquely exchange group ring,as a middle ring of the uniquely clean ring and the USC ring,does not possess this property,and so does the uniquely exchange group ring.

  10. Two directional microstructure and effects of nanoscale dispersed Si particles on microhardness and tensile properties of AlSi7Mg melt-spun alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xixi, E-mail: dongxx09@mails.tsinghua.edu.cn [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); He, Liangju [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); School of Aerospace, Tsinghua University, Beijing 100084 (China); Mi, Guangbao [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); Li, Peijie [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2015-01-05

    Highlights: • Both surface and cross-sectional microstructure of AlSi7Mg ribbon were characterized. • 13–50 nm and 50-hundreds of nm Si particles were dispersed both in α-Al and its boundary. • Tensile property of AlSi7Mg ribbon was studied with UTS 1.5 times higher than ingot. • Effects of nanoscale Si particles on hardness and tensile properties were provided. - Abstract: The two directional microstructure and multiple mechanical properties of the AlSi7Mg ribbon produced by melt-spun were investigated by optical microscopy (OM), field emission gun scanning electron microscope (FEGSEM), X-ray diffraction (XRD), microhardness and tensile tests. Both the surface and cross-sectional microstructure of the melt-spun ribbon were characterized in detail to give a clear and integrated description of the microstructure. Two kinds of nanoscale Si particles were observed, i.e., small Si particles ranging from 13 to 50 nm and large Si particles ranging from 50 nm to several hundreds of nanometers with clear size boundary were dispersed both in the interior and boundary of fine α-Al. XRD results revealed supersaturated solution of Si in Al matrix to be 0.62 at.%. The ultimate tensile strength, yield strength, and hardness of the ribbon were 1.53, 1.75 and 1.56 times higher than that of the conventional cast ingot separately. The breaking elongation of the ribbon was 1.73% with intergranular fracture feature. The effects of nanoscale dispersed Si particles on the significant improvement of both hardness and tensile properties of the AlSi7Mg melt-spun ribbon were discussed in detail.

  11. Microstructure and mechanical properties of ZrO{sub 2} particle dispersion strengthened 16MnV steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.A. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Wang, N. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); CNOOC Research Institute of Oil and Petrochemicals (CRI), Beijing 100000 (China); Yang, Y.J.; Zhong, H. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Ma, M.Z., E-mail: mz550509@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, X.Y.; Liu, R.P. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2017-04-24

    The dispersion strengthened 16MnV steels with 0.5 wt% and 1.2 wt% ZrO{sub 2} particles were prepared using medium frequency induction melting furnace. The ZrO{sub 2} particles mixed with iron powder were added into the 16MnV steel through cored-wire injection process. Optical metallographic microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to observe and analyze the microstructure, fracture morphology, dislocation configuration and strengthening mechanism of ZrO{sub 2} particle dispersion strengthened 16MnV steel under as-cast, normalizing and quenching states. Results showed that the strength of 16MnV steel under various states increased significantly after the addition of dispersed ZrO{sub 2} particles. Analysis indicates that the dislocation cell formed by high density dislocation around ZrO{sub 2} particles and attractive interaction between those particles are the main strengthening mechanism of dispersion strengthened 16MnV steel. The tensile test results showed that remarkable strengthening effect of ZrO{sub 2} particle on 16MnV steel has been observed. As the addition of 1.2 wt% ZrO{sub 2}, the improvement of strength in ZrO{sub 2}/16MnV is approximately 37.69% for as-casting, 24.2% after normalization and 29.96% after quenching, respectively. The normalized ZrO{sub 2}/16MnV with 1.2 wt% ZrO{sub 2} has the highest strength of 1453 MPa.

  12. Physicochemical properties of direct compression tablets with spray dried and ball milled solid dispersions of tadalafil in PVP-VA.

    Science.gov (United States)

    Wlodarski, K; Tajber, L; Sawicki, W

    2016-12-01

    The aim of this research was to develop immediate release tablets comprising solid dispersion (IRSDTs) of tadalafil (Td) in a vinylpyrrolidone and vinyl acetate block copolymer (PVP-VA), characterized by improved dissolution profiles. The solid dispersion of Td in PVP-VA (Td/PVP-VA) in a weight ratio of 1:1 (w/w) was prepared using two different processes i.e. spray drying and ball milling. While the former process has been well established in the formulation of IRSDTs the latter has not been exploited in these systems yet. Regardless of the preparation method, both Td/PVP-VA solid dispersions were amorphous as confirmed by PXRD, DSC and FTIR. However, different morphology of particles (SEM) resulted in differences in water apparent solubility and disk intrinsic dissolution rate (DIDR). Both solid dispersions and crystalline Td were successfully made into directly compressible tablets at three doses of Td, i.e. 2.5mg, 10mgand20mg, yielding nine different formulations (D 1 -D 9 ). Each of the lots met the requirements set by Ph.Eur. and was evaluated with respect to appearance, diameter, thickness, mass, hardness, friability, disintegration time and content of Td. IRSDTs performed as supersaturable formulations and had significantly improved water dissolution profiles in comparison with equivalent tablets containing crystalline Td and the marketed formulations. Tablets with both spray dried and ball milled Td/PVP-VA revealed the greatest improvement in dissolution depending on the investigated doses, i.e. 2.5mgand20mg, respectively. Also, dissolution of Td from Td/PVP-VA delivered in different forms occurred in the following order: powders>tablets>capsules. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Processing/microstructure/mechanical-property relationships in FeAlZrB with and without an oxide dispersion

    International Nuclear Information System (INIS)

    Strothers, S.D.H.

    1991-01-01

    The effect of powder and processing variables on the microstructure of an extruded FeAlZrB alloy was investigated. Results shows that key parameters in microstructural development are extrusion temperature and powder particle size. In addition to powder and processing variables, the effect of a 1 vol% Y 2 O 3 dispersion was investigated. The microstructure of this material was very fine-grained. By manipulating powder and processing parameters and heat treatments, a very large range of microstructures were obtained. This enabled an evaluation of the role of microstructure and grain size on the room-temperature and elevated-temperature mechanical behavior of this alloy. At 1,100K the coarse-grained materials exhibited larger yield strengths in tension with the exception of the very-fine-grained oxide-dispersion-strengthened extrusions. These had the highest yields strengths despite their fine grain sizes. The oxide-dispersion-strengthened alloys also showed the greatest compression creep resistance at 1,100K even when heat treated to large grain sizes

  14. Dispersion of nano-silica in monomer casting nylon6 and its effect on the structure and properties of composites

    Directory of Open Access Journals (Sweden)

    2010-07-01

    Full Text Available To promote dispersion of nano-silica in monomer casting nylon6 (MC nylon6, nano-silica was dispersed in melted caprolactam with the assistance of ultrasound, anionic polymerization was then initiated to form silica/MC nylon6 in-situ nanocomposites. It was found that hydrogen bonds were formed between nano-silica and caprolactam, in the meantime, ultrasound helped to break the nanoparticles aggregations into smaller ones or even mono-dispersing particles. Therefore, the agglomerated nanoparticles were pulled apart and stabilized by caprolactam. Additionally, the rapid anionic polymerization of caprolactam also contributed to the avoidance of re-agglomeration and deposition of nanoparticles during the polymerization process, leading to the uniform distribution of nanoparticles in the polymer matrix. Mechanical tests indicated that the silica/MC nylon6 in-situ nanocomposites prepared according to the above strategy were simultaneously toughened, strengthened and stiffened. Thermogravimetric analysis (TGA results showed that thermal stability of nanocomposites was notably improved compared to neat MC nylon6.

  15. The Effect of Dispersion Phases of SiC and Al2O3 on the Properties of Galvanic Nickel Coatings

    OpenAIRE

    Kozik A.; Nowak M.; Gawlik M.; Bigaj M.; Karaś M.

    2016-01-01

    In this study, Ni, Ni-SiC and Ni-Al2O3 coatings were electroplated on the 2xxx series aluminium alloy. The following parameters of the electroplating process were applied: current density - 4A/dm2, time - 60 minutes, and temperature - 60°C. Hard particles of submicrometric size were used. The results of the research showing the effect of the addition of hard particles (introduced into the nickel bath as a dispersed phase) on the properties of coatings, including the effect of the type (SiC or...

  16. Determining the Surfactant Consistent with Concrete in order to Achieve the Maximum Possible Dispersion of Multi walled Carbon Nano tubes in Keeping the Plain Concrete Properties

    International Nuclear Information System (INIS)

    Adresi, M.; Hassani, A.; Javadian, S.; Tulliani, J. M.

    2016-01-01

    A new surfactant combination compatible with concrete formulation is proposed to avoid unwanted air bubbles created during mixing process in the absence of a defoamer and to achieve the uniform and the maximum possible dispersion of multi walled carbon nano tubes (MWCNTs) in water and subsequently in concrete. To achieve this goal, three steps have been defined: (1) concrete was made with different types and amount of surfactants containing a constant amount of MWCNTs (0.05 wt%) and the air bubbles were eliminated with a proper defoamer. (2) Finding a compatible surfactant with concrete compositions and eliminating unwanted air bubbles in the absence of a common defoamer are of fundamental importance to significantly increase concrete mechanical properties. In this step, the results showed that the poly carboxylate super plasticizer (SP-C) (as a compatible surfactant) dispersed MWCNTs worse than SDS/DTAB but unwanted air bubbles were removed, so the defoamer can be omitted in the mixing process. (3) To solve the problem, a new compatible surfactant composition was developed and different ratios of surfactants were tested and evaluated by means of performance criteria mentioned above. The results showed that the new surfactant composition (SDS and SP-C) can disperse MWCNTs around 24% more efficiently than the other surfactant compositions.

  17. Influence of the interface corrugation on the subband dispersions and the optical properties of (113)-oriented GaAs/AlAs superlattices

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Lüerssen, D.; Kalt, H.

    1996-01-01

    We report on the influence of the interface corrugation in (113)-grown GaAs/AlAs superlattices on their band-edge optical properties both in theory and experiment. We calculate the subband dispersions and the optical anisotropies in a multiband k . p formalism. The dominating contribution...... to the optical anisotropies is found to be due to the intrinsic properties of the valence-band structure. The corrugation modifies the density of states only slightly, giving no evidence of a quantum-win behavior. By comparing the calculation with the experimental optical anisotropy, we can estimate...... of the localized type-I states at the band-edge show an enhanced optical anisotropy in comparison to the luminescence of the extended states, revealing the anisotropic nature of their localization sites. In type-II samples, deeply localized, isolated type-I states (Gamma quantum boxes) dominate the luminescence...

  18. Mechanical properties of brazing joints of alumina dispersion strengthened copper to 316 stainless steel for fusion reactor divertor

    International Nuclear Information System (INIS)

    Nishi, Hiroshi; Araki, Toshiaki.

    1994-01-01

    Brazing of alumina dispersion strengthened copper to 316 stainless steel was carried out with the brazing parameters such as brazing alloy, clearance and time to investigate the influence of brazing conditions on the joint strength. Tensile and Charpy impact tests of the joint specimens were performed to evaluate their strength. Microstructure and hardness of the brazed zone were examined with an optical microscope and a Vickers hardness tester. The excellent brazing joint strength was achieved with BAu-2 brazing alloy. The tensile strength of the joint with the brazing clearance of 0.2mm and the brazing time of 300s was as large as that of the diffusion bonding joint. However, Charpy absorbed energy of the brazing was lower than that of the diffusion bonding. Alumina dispersion strengthened copper remelted near the brazed zone because of diffusion of the brazing alloy, and the specimens fractured at the remelted zone. The brazed zone included many voids, which caused a scattering of the strength. (author)

  19. Effects of SiO2 nano-particles on tribological and mechanical properties of aluminum matrix composites by different dispersion methods

    Science.gov (United States)

    Azadi, Mahboobeh; Zolfaghari, Mehrdad; Rezanezhad, Saeid; Azadi, Mohammad

    2018-05-01

    This study has been presented with mechanical properties of aluminum matrix composites, reinforced by SiO2 nano-particles. The stir casting method was employed to produce various aluminum matrix composites. Different composites by varying the SiO2 nano-particle content (including 0.5 and 1 weight percents) and two dispersion methods (including ball-milling and pre-heating) were made. Then, the density, the hardness, the compression strength, the wear resistance and the microstructure of nano-composites have been studied in this research. Besides, the distribution of nano-particles in the aluminum matrix for all composites has been also evaluated by the field emission scanning electron microscopy (FESEM). Obtained results showed that the density, the elongation and the ultimate compressive strength of various nano-composites decreased by the presence of SiO2 nano-particles; however, the hardness, the wear resistance, the yield strength and the elastic modulus of composites increased by auditioning of nano-particles to the aluminum alloy. FESEM images indicated better wetting of the SiO2 reinforcement in the aluminum matrix, prepared by the pre-heating dispersion method, comparing to ball-milling. When SiO2 nano-particles were added to the aluminum alloy, the morphology of the Si phase and intermetallic phases changed, which enhanced mechanical properties. In addition, the wear mechanism plus the friction coefficient value were changed for various nano-composites with respect to the aluminum alloy.

  20. Hydrodynamic disperser

    Energy Technology Data Exchange (ETDEWEB)

    Bulatov, A.I.; Chernov, V.S.; Prokopov, L.I.; Proselkov, Yu.M.; Tikhonov, Yu.P.

    1980-01-15

    A hydrodynamic disperser is suggested which contains a housing, slit nozzles installed on a circular base arranged opposite from each other, resonators secured opposite the nozzle and outlet sleeve. In order to improve the effectiveness of dispersion by throttling the flow, each resonator is made in the form of a crimped plate with crimpings that decrease in height in a direction towards the nozzle.

  1. Stabilization of aqueous nanoscale zerovalent iron dispersions by anionic polyelectrolytes: adsorbed anionic polyelectrolyte layer properties and their effect on aggregation and sedimentation

    International Nuclear Information System (INIS)

    Phenrat, Tanapon; Saleh, Navid; Sirk, Kevin; Kim, Hye-Jin; Tilton, Robert D.; Lowry, Gregory V.

    2008-01-01

    Nanoscale zerovalent iron (NZVI) particles are 5-40 nm sized Fe 0 /Fe-oxide particles that rapidly transform many environmental contaminants to benign products and are a promising in situ remediation agent. Rapid aggregation and limited mobility in water-saturated porous media limits the ability to deliver NZVI dispersions in the subsurface. This study prepares stable NZVI dispersions through physisorption of commercially available anionic polyelectrolytes, characterizes the adsorbed polymer layer, and correlates the polymer coating properties with the ability to prevent rapid aggregation and sedimentation of NZVI dispersions. Poly(styrene sulfonate) with molecular weights of 70 k and 1,000 k g/mol (PSS70K and PSS1M), carboxymethyl cellulose with molecular weights of 90 k and 700 k g/mol (CMC90K and CMC700K), and polyaspartate with molecular weights of 2.5 k and 10 k g/mol (PAP2.5K and 10K) were compared. Particle size distributions were determined by dynamic light scattering during aggregation. The order of effectiveness to prevent rapid aggregation and stabilize the dispersions was PSS70K(83%) > ∼PAP10K(82%) > PAP2.5K(72%) > CMC700K(52%), where stability is defined operationally as the volume percent of particles that do not aggregate after 1 h. CMC90K and PSS1M could not stabilize RNIP relative to bare RNIP. A similar trend was observed for their ability to prevent sedimentation, with 40, 34, 32, 20, and 5 wt%, of the PSS70K, PAP10K, PAP2.5K, CMC700K, and CMC90K modified NZVI remaining suspended after 7 h of quiescent settling, respectively. The stable fractions with respect to both aggregation and sedimentation correlate well with the adsorbed polyelectrolyte mass and thickness of the adsorbed polyelectrolyte layers as determined by Oshima's soft particle theory. A fraction of the particles cannot be stabilized by any modifier and rapidly agglomerates to micron sized aggregates, as is also observed for unmodified NZVI. This non-dispersible fraction is

  2. Single-particle properties of N = 12 to N = 20 silicon isotopes within the dispersive optical model

    Science.gov (United States)

    Bespalova, O. V.; Ermakova, T. A.; Klimochkina, A. A.; Spasskaya, T. I.

    2017-09-01

    Experimental neutron and proton single-particle energies in N = 12 to N = 20 silicon isotopes and data on neutron and proton scattering by nuclei of the isotope 28Si are analyzed on the basis of the dispersive optical model. Good agreement with available experimental data was attained. The occupation probabilities calculated for the single-particle states in question suggest a parallel-type filling of the 1 d and 2 s 1/2 neutron states in the isotopes 26,28,30,32,34Si. The single-particle spectra being considered are indicative of the closure of the Z = 14 proton subshell in the isotopes 30,32,34Si and the N = 20 neutron shell.

  3. Influence of Prosolv and Prosolv:Mannitol 200 direct compression fillers on the physicomechanical properties of atorvastatin oral dispersible tablets.

    Science.gov (United States)

    Gowda, Veeran; Pabari, Ritesh M; Kelly, John G; Ramtoola, Zebunnissa

    2015-06-01

    The objective of the present study was to evaluate the influence of Prosolv® and Prosolv®: Mannitol 200 direct compression (DC) fillers on the physicomechanical characteristics of oral dispersible tablets (ODTs) of crystalline atorvastatin calcium. ODTs were formulated by DC and were analyzed for weight uniformity, hardness, friability, drug content, disintegration and dissolution. Three disintegration time (DT) test methods; European Pharmacopoeia (EP) method for conventional tablets (Method 1), a modification of this method (Method 2) and the EP method for oral lyophilisates (Method 3) were compared as part of this study. All ODTs showed low weight variation of tablet hardness of ∼ 73 N, hardness decreased with increasing mannitol content. Friability of all formulations was 60% within 5 min despite the drug being crystalline. Prosolv® and Prosolv®:Mannitol-based ODTs are suitable for ODT formulations by DC to give ODTs with high mechanical strength, rapid disintegration and dissolution.

  4. Preparation of nickel-based amorphous alloys with finely dispersed lead and lead-bismuth particles and their superconducting properties

    International Nuclear Information System (INIS)

    Inoue, A.; Oguchi, M.; Harakawa, Y.; Masumoto, T.; Matsuzaki, K.

    1986-01-01

    The application of the melt-quenching technique to Ni-Si-B-Pb, Ni-P-B-Pb, Ni-Si-B-Pb-Bi and Ni-P-B-Pb-Bi alloys containing immiscible elements such as lead and bismuth has been tried and it has been found to result in the formation of a new type of material consisting of fine fcc Pb or hcp epsilon(Pb-Bi) + bct X(Pb-Bi) particles dispersed uniformly in the nickel-based amorphous matrix. The particle size and interparticle distance were 1 to 3 and 1 to 4 μm, respectively, for the lead phase, and less than 0.2 to 0.5 μm and 0.2 to 1.0 μm for the Pb-Bi phase. The uniform dispersion of such fine particles into the amorphous matrix was achieved in the composition range below about 6 at% Pb and 7 at% (Pb+Bi). Additionally, these amorphous alloys have been found to exhibit a superconductivity by the proximity effect of fcc Pb or epsilon(Pb-Bi) superconducting particles. The transition temperature Tsub(c) was in the range 6.8 to 7.5 K for the Ni-Si (or P)-B-Pb alloys and 8.6 to 8.8 K for the Ni-Si (or P)-B-Pb-Bi alloys. The upper critical field Hsub(c2) and the critical current density Jsub(c) for (Nisub(0.8)Psub(0.1)Bsub(0.1)) 95 Pb 3 Bi 2 at 4.2 K were, respectively, about 1.6 T and of the order of 7 x 10 7 Am -2 at zero applied field. (author)

  5. Physical Properties and Effect in a Battery of Safety Pharmacology Models for Three Structurally Distinct Enteric Polymers Employed as Spray-dried Dispersion Carriers

    Directory of Open Access Journals (Sweden)

    Ryan M Fryer

    2016-10-01

    Full Text Available Establishing a wide therapeutic index (TI for pre-clinical safety is important during lead optimization (LO in research, prior to clinical development, although is often limited by a molecules physiochemical characteristics. Recent advances in the application of the innovative vibrating mesh spray-drying technology to prepare amorphous solid dispersions may offer an opportunity to achieve high plasma concentrations of poorly soluble NCEs to enable testing and establishment of a wide TI in safety pharmacology studies. While some of the amorphous solid dispersion carriers are generally recognized as safe for clinical use, whether they are sufficiently benign to enable in vivo pharmacology studies has not been sufficiently demonstrated. Thus, the physical properties, and effect in a battery of in vivo safety pharmacology models, were assessed in three classes of polymers employed as spray-dried dispersion carriers. The polymers (HPMC-AS, Eudragit, PVAP displayed low affinity with acetone/methanol, suitable for solvent-based spray drying. The water sorption of the polymers was moderate, and the degree of hysteresis of HPMC-AS was smaller than Eudragit and PVAP indicating the intermolecular interaction of water-cellulose molecules is weaker than water-acrylate or water-polyvinyl molecules. The polymer particles were well-suspended without aggregation with a mean particle size less than 3 µm in an aqueous vehicle. When tested in conscious Wistar Han rats in safety pharmacology models (n=6-8/dose/polymer investigating effects on CNS, gastrointestinal, and cardiovascular function, no liabilities were identified at any dose tested (30-300 mg/kg PO, suspension. In brief, the polymers had no effect in a modified Irwin test that included observational and evoked endpoints related to stereotypies, excitation, sedation, pain/anesthesia, autonomic balance, reflexes, and others. No effect of the polymers on gastric emptying or intestinal transit was observed

  6. Dynamic Properties of Glass-Formers Governed by the Frequency Dispersion of the Structural α-Relaxation: Examples from Prilocaine.

    Science.gov (United States)

    Wojnarowska, Z; Rams-Baron, M; Knapik, J; Ngai, K L; Kruk, D; Paluch, M

    2015-10-01

    General and fundamental properties of glass-formers of various chemical bonding and physical structures have been found in the recent past. These important findings should be key to gain basic understanding of the dynamics at all time scales leading to glass transition. However, the entirety of these general properties has not been found in a single glass-former. For others to appreciate the importance of these properties, they need to collect the supporting experimental data from different glass-formers scattered over many publications. This hurdle may account for the current lack of universal recognition of the importance of these general properties by the research community. In this paper we present experimental studies of the dynamic processes over a broad range of time scales of a single glass-former, prilocaine. Practically the entire collection of fundamental properties has been found in this system. The advance should heighten the awareness of the importance of these properties in anyone's effort to solve the glass transition problem.

  7. Dispersion of SiC nanoparticles in cellulose for study of tensile, thermal and oxygen barrier properties.

    Science.gov (United States)

    Kisku, Sudhir K; Dash, Satyabrata; Swain, Sarat K

    2014-01-01

    Cellulose/silicon carbide (cellulose/SiC) nanobiocomposites were prepared by solution technique. The interaction of SiC nanoparticles with cellulose were confirmed by Fourier transformed infrared (FTIR) spectroscopy. The structure of cellulose/SiC nanobiocomposites was investigated by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The tensile properties of the nanobiocomposites were improved as compared with virgin cellulose. Thermal stabilities of cellulose/SiC nanobiocomposites were studied by thermogravimetric analysis (TGA). The cellulose/SiC nanobiocomposites were thermally more stable than the raw cellulose. It may be due to the delamination of SiC with cellulose matrix. The oxygen barrier properties of cellulose composites were measured using gas permeameter. A substantial reduction in oxygen permeability was obtained with increase in silicon carbide concentrations. The thermally resistant and oxygen barrier properties of the prepared nanobiocomposites may enable the materials for the packaging applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Enhancement of the energy storage properties of supercapacitors using graphene nanosheets dispersed with metal oxide-loaded carbon nanotubes

    Science.gov (United States)

    Rakhi, R. B.; Alshareef, H. N.

    2011-10-01

    Graphene nanosheets (GNs) dispersed with SnO2 nanoparticles loaded multiwalled carbon nanotubes (SnO2-MWCNTs) were investigated as electrode materials for supercapacitors. SnO2-MWCNTs were obtained by a chemical method followed by calcination. GNs/SnO2-MWCNTs nanocomposites were prepared by ultrasonication of the GNs and SnO2-MWCNTs. Electrochemical double layer capacitors were fabricated using the composite as the electrode material and aqueous KOH as the electrolyte. Electrochemical performance of the composite electrodes were compared to that of pure GNs electrodes and the results are discussed. Electrochemical measurements show that the maximum specific capacitance, power density and energy density obtained for supercapacitor using GNs/SnO2-MWCNTs nanocomposite electrodes were respectively 224 F g-1, 17.6 kW kg-1 and 31 Wh kg-1. The fabricated supercapacitor device exhibited excellent cycle life with ∼81% of the initial specific capacitance retained after 6000 cycles. The results suggest that the hybrid composite is a promising supercapacitor electrode material.

  9. Enhancement of the energy storage properties of supercapacitors using graphene nanosheets dispersed with metal oxide-loaded carbon nanotubes

    KAUST Repository

    Baby, Rakhi Raghavan

    2011-10-01

    Graphene nanosheets (GNs) dispersed with SnO2 nanoparticles loaded multiwalled carbon nanotubes (SnO2-MWCNTs) were investigated as electrode materials for supercapacitors. SnO2-MWCNTs were obtained by a chemical method followed by calcination. GNs/SnO2-MWCNTs nanocomposites were prepared by ultrasonication of the GNs and SnO 2-MWCNTs. Electrochemical double layer capacitors were fabricated using the composite as the electrode material and aqueous KOH as the electrolyte. Electrochemical performance of the composite electrodes were compared to that of pure GNs electrodes and the results are discussed. Electrochemical measurements show that the maximum specific capacitance, power density and energy density obtained for supercapacitor using GNs/SnO 2-MWCNTs nanocomposite electrodes were respectively 224 F g -1, 17.6 kW kg-1 and 31 Wh kg-1. The fabricated supercapacitor device exhibited excellent cycle life with ∼81% of the initial specific capacitance retained after 6000 cycles. The results suggest that the hybrid composite is a promising supercapacitor electrode material. © 2011 Elsevier B.V. All rights reserved.

  10. Preparation and third-order nonlinear optical property of poly(urethane-imide containing dispersed red chromophore

    Directory of Open Access Journals (Sweden)

    2008-11-01

    Full Text Available A novel poly(urethane-imide (PUI containing dispersed red chromophore was synthesized. The PUI was characterized by FT-IR, UV-Vis, DSC and TGA. The results of DSC and TGA indicated that the PUI exhibited high thermal stability up to its glass-transition temperature (Tg of 196°C and 5% heat weight loss temperature of 229°C. According to UV-Vis spectrum and working curve, the maximum molar absorption coefficient and absorption wavelength were measured. They were used to calculate the third-order nonlinear optical coefficient χ(3. At the same time, the chromophore density of PUI, nonlinear refractive index coefficient and molecular hyperpolarizability of PUI were obtained. The fluorescence spectra of PUI and model compound DR-19 were determined at excitation wavelength 300 nm. The electron donor and acceptor in polymer formed the exciplex through the transfer of the electric charges. The results show that the poly(urethane-imide is a promising candidate for application in optical devices.

  11. One-baryon spectrum and analytical properties of one-baryon dispersion curves in 3 + 1 dimensional strongly coupled lattice QCD with three flavors

    International Nuclear Information System (INIS)

    Faria da Veiga, Paulo A.; O’Carroll, Michael; Valencia Alvites, José C.

    2016-01-01

    Considering a 3 + 1 dimensional lattice quantum chromodynamics (QCD) model defined with the improved Wilson action, three flavors, and 4 × 4 Dirac spin matrices, in the strong coupling regime, we reanalyze the question of the existence of the eightfold way baryons and complete our previous work where the existence of isospin octet baryons was rigorously solved. Here, we show the existence of isospin decuplet baryons which are associated with isolated dispersion curves in the subspace of the underlying quantum mechanical Hilbert space with vectors constructed with an odd number of fermion and antifermion basic quark and antiquark fields. Moreover, smoothness properties for these curves are obtained. The present work deals with a case for which the traditional method to solve the implicit equation for the dispersion curves, based on the use of the analytic implicit function theorem, cannot be applied. We do not have only one but two solutions for each one-baryon decuplet sector with fixed spin third component. Instead, we apply the Weierstrass preparation theorem, which also provides a general method for the general degenerate case. This work is completed by analyzing a spectral representation for the two-baryon correlations and providing the leading behaviors of the field strength normalization and the mass of the spectral contributions with more than one-particle. These are needed results for a rigorous analysis of the two-baryon and meson-baryon particle spectra.

  12. One-baryon spectrum and analytical properties of one-baryon dispersion curves in 3 + 1 dimensional strongly coupled lattice QCD with three flavors

    Energy Technology Data Exchange (ETDEWEB)

    Faria da Veiga, Paulo A., E-mail: veiga@icmc.usp.br; O’Carroll, Michael, E-mail: michaelocarroll@gmail.com; Valencia Alvites, José C., E-mail: cien.mat@hotmail.com [Departamento de Matemática Aplicada e Estatística, ICMC, USP-São Carlos, C.P. 668, São Carlos, SP 13560-970 (Brazil)

    2016-03-15

    Considering a 3 + 1 dimensional lattice quantum chromodynamics (QCD) model defined with the improved Wilson action, three flavors, and 4 × 4 Dirac spin matrices, in the strong coupling regime, we reanalyze the question of the existence of the eightfold way baryons and complete our previous work where the existence of isospin octet baryons was rigorously solved. Here, we show the existence of isospin decuplet baryons which are associated with isolated dispersion curves in the subspace of the underlying quantum mechanical Hilbert space with vectors constructed with an odd number of fermion and antifermion basic quark and antiquark fields. Moreover, smoothness properties for these curves are obtained. The present work deals with a case for which the traditional method to solve the implicit equation for the dispersion curves, based on the use of the analytic implicit function theorem, cannot be applied. We do not have only one but two solutions for each one-baryon decuplet sector with fixed spin third component. Instead, we apply the Weierstrass preparation theorem, which also provides a general method for the general degenerate case. This work is completed by analyzing a spectral representation for the two-baryon correlations and providing the leading behaviors of the field strength normalization and the mass of the spectral contributions with more than one-particle. These are needed results for a rigorous analysis of the two-baryon and meson-baryon particle spectra.

  13. Molecular structure of sodium lignosulfonate from different sources and their properties as dispersant of TiO2 slurry

    Science.gov (United States)

    Haifeng Zhou; Dongjie Yang; Junyong Zhu

    2016-01-01

    The molecular structure and properties of four sodium lignosulfates (LSs) derived from pulping or bioethanol production were evaluated and compared. SXP and SAL were produced by sulfite pulping and sulfonation reaction of lignin from alkali pulping of poplar, respectively. LS-180 and LS-150 were from sulfite pretreatment to overcome recalcitrance of lignocelluloses (...

  14. Elevated temperature tensile properties of borated 304 stainless steel: Effect of boride dispersion on strength and ductility

    International Nuclear Information System (INIS)

    Stephens, J.J.; Sorenson, K.B.; McConnell, P.

    1992-01-01

    Conventional cast and wrought (open-quotes Ingot Metallurgyclose quotes) borated 304 stainless steel has been used for a number of years in spent fuel storage applications where a combination of structural integrity and neutron criticality control are required. Similar requirements apply for materials used in transport cask baskets. However, in the high boron contents (>1.0 wt. %) which are most useful for criticality control, the conventional cast and wrought material suffers from low ductility as well as low impact toughness. The microstructural reason for these poor properties is the relatively coarse size of the boride particles in these alloys, which act as sites for crack initiation. Recently, a open-quotes premiumclose quotes grade of borated 304 stainless steel has been introduced (Strober and Smith, 1988) which is made by a Powder Metallurgy (PM) process. This material has greatly improved ductility and impact properties relative to the conventional cast and wrought product. In addition, an ASTM specification (ATSM A887) has been developed for borated stainless steel, containing 8 different material Types with respect to boron content - with the highest level (Type B7) having permissible range from 1.75 to 2.25 wt. % boron - and each Type contains two different Grades of material based on tensile and impact properties. While the ASTM specification is properties-based and does not require a specific production process for a particular grade of material, the PM material qualifies as open-quotes Grade Aclose quotes material while the conventional Ingot Metallurgy (IM) material generally qualifies as open-quotes Grade Bclose quotes material. This paper presents a comparison of the tensile properties of PM open-quotes Grade Aclose quotes material with that of the conventional IM open-quotes Grade Bclose quotes material for two selected Types (i.e., boron contents) as defined by the ASTM A887 specification: Types 304B5 and 304B7

  15. Dispersion stability of thermal nanofluids

    Directory of Open Access Journals (Sweden)

    Fan Yu

    2017-10-01

    Full Text Available Thermal nanofluids, the engineered fluids with dispersed functional nanoparticles, have exhibited extraordinary thermophysical properties and added functionalities, and thus have enabled a broad range of important applications. The poor dispersion stability of thermal nanofluids, however, has been considered as a long-existing issue that limits their further development and practical application. This review overviews the recent efforts and progresses in improving the dispersion stability of thermal nanofluids such as mechanistic understanding of dispersion behavior of nanofluids, examples of both water-based and oil-based nanofluids, strategies to stabilize nanofluids, and characterization techniques for dispersion behavior of nanofluids. Finally, on-going research needs, and possible solutions to research challenges and future research directions in exploring stably dispersed thermal nanofluids are discussed. Keywords: Thermal nanofluids, Dispersion, Aggregation, Electrostatic stabilization, Steric stabilization

  16. The human CD8β M-4 isoform dominant in effector memory T cells has distinct cytoplasmic motifs that confer unique properties.

    Directory of Open Access Journals (Sweden)

    Deepshi Thakral

    Full Text Available The CD8 co-receptor influences T cell recognition and responses in both anti-tumor and anti-viral immunity. During evolution in the ancestor of humans and chimpanzees, the CD8B gene acquired two additional exons. As a result, in humans, there are four CD8β splice variants (M1 to M4 that differ in their cytoplasmic tails. The M-1 isoform which is the equivalent of murine CD8β, is predominantly expressed in naïve T cells, whereas, the M-4 isoform is predominantly expressed in effector memory T cells. The characteristics of the M-4 isoform conferred by its unique 36 amino acid cytoplasmic tail are not known. In this study, we identified a dihydrophobic leucine-based receptor internalization motif in the cytoplasmic tail of M-4 that regulated its cell surface expression and downregulation after activation. Further the M-4 cytoplasmic tail was able to associate with ubiquitinated targets in 293T cells and mutations in the amino acids NPW, a potential EH domain binding site, either enhanced or inhibited the interaction. In addition, the M-4 tail was itself mono-ubiquitinated on a lysine residue in both 293T cells and a human T cell line. When peripheral blood human T cells expressed CD8αβ M-4, the frequency of MIP-1β secreting cells responding to antigen presenting cells was two-fold higher as compared to CD8αβ M-1 expressing T cells. Thus, the cytoplasmic tail of the CD8β M-4 isoform has unique characteristics, which likely contributed to its selective expression and function in human effector memory T cells.

  17. Synthesis and dyeing properties of some new monoazo disperse dyes derived from 2-amino-4-(2′,4′-dichlorophenyl-1,3 thiazole

    Directory of Open Access Journals (Sweden)

    Divyesh R. Patel

    2014-12-01

    Full Text Available Ten new monoazo disperse dyes (4a–j have been synthesized by coupling of diazotized 2-amino-4-(2′,4′-dichlorophenyl-1,3 thiazole (2 with various N-alkyl derivatives of substituted aniline (3a–j and their dyeing performance on polyester fiber has been assessed. These dyes are characterized by elemental analysis, UV–vis spectra, IR and NMR spectroscopy. The absorption maxima (λmax were recorded in DMF and were found to be in the range of 530–600 nm. The dyed polyester fabric showed fair to very good light fastness and very good to excellent washing and rubbing fastness properties with superior depth and levelness.

  18. The Effect of Pigment Volume Concentration on Film Formation and the Mechanical Properties of Coatings Based on Water-Dispersion Paint and Varnish Materials

    Science.gov (United States)

    Kasyanenko, I. M.; Kramarenko, V. Yu.

    2018-01-01

    The effect of pigment volume concentration (PVC) on the film formation process and properties of coatings based on the water dispersion of an Acronal 290D styrene-acrylate copolymer and a pigment/filler system used for paint materials in construction was investigated. An analysis of the results obtained is performed within the framework of the concept of the critical PVC. It is shown that the initiation and development of internal stresses occurs the faster, the higher the PVC, but the position of the maximum or the inflection point of the internal stress-drying time curve complies with a universal value of the solid volume content in the compositions. It is found that the internal stresses and Young's modulus of coatings are characterized by an extreme concentration relation that, for the reduced elastic modulus, can be described by a system of equations based on the Halpin-Tsai equation.

  19. Probing the properties of the pulsar wind via studying the dispersive effects in the pulses from the pulsar companion in a double neutron-star binary system

    Science.gov (United States)

    Yi, Shu-Xu; Cheng, K.-S.

    2017-12-01

    The velocity and density distribution of e± in the pulsar wind are crucial distinction among magnetosphere models, and contain key parameters determining the high-energy emission of pulsar binaries. In this work, a direct method is proposed, which might probe the properties of the wind from one pulsar in a double-pulsar binary. When the radio signals from the first-formed pulsar travel through the relativistic e± flow in the pulsar wind from the younger companion, the components of different radio frequencies will be dispersed. It will introduce an additional frequency-dependent time-of-arrival delay of pulses, which is function of the orbital phase. In this paper, we formulate the above-mentioned dispersive delay with the properties of the pulsar wind. As examples, we apply the formula to the double-pulsar system PSR J0737-3039A/B and the pulsar-neutron star binary PSR B1913+16. For PSR J0737-3039A/B, the time delay in 300 MHz is ≲ 10 μ s-1 near the superior conjunction, under the optimal pulsar wind parameters, which is approximately half of the current timing accuracy. For PSR B1913+16, with the assumption that the neutron-star companion has a typical spin-down luminosity of 1033 erg s-1, the time delay is as large as 10 - 20 μ s-1 in 300 MHz. The best timing precision of this pulsar is ∼ 5 μ s-1 in 1400 MHz. Therefore, it is possible that we can find this signal in archival data. Otherwise, we can set an upper limit on the spin-down luminosity. Similar analysis can be applied to other 11 known pulsar-neutron star binaries.

  20. Fabrication, characterization and gamma rays shielding properties of nano and micro lead oxide-dispersed-high density polyethylene composites

    Science.gov (United States)

    Mahmoud, Mohamed E.; El-Khatib, Ahmed M.; Badawi, Mohamed S.; Rashad, Amal R.; El-Sharkawy, Rehab M.; Thabet, Abouzeid A.

    2018-04-01

    Polymer composites of high-density polyethylene (HD-PE) filled with powdered lead oxide nanoparticles (PbO NPs) and bulk lead oxide (PbO Blk) were prepared with filler weight fraction [10% and 50%]. These polymer composites were investigated for radiation-shielding of gamma-rays emitted from radioactive point sources [241Am, 133Ba, 137Cs, and 60Co]. The polymer was found to decrease the heaviness of the shielding material and increase the flexibility while the metal oxide fillers acted as principle radiation attenuators in the polymer composite. The prepared composites were characterized by Fourier transform infrared spectrophotometer (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area (BET) and field emission transmission electron microscope (FE-TEM). The morphological analysis of the assembled composites showed that, PbO NPs and PbO Blk materials exhibited homogenous dispersion in the polymer-matrix. Thermogravimetric analysis (TGA) demonstrated that the thermal-stability of HD-PE was enhanced in the presence of both PbO Blk and PbO NPs. The results declared that, the density of polymer composites was increase with the percentage of filler contents. The highest density value was identified as 1.652 g cm-3 for 50 wt% of PbO NPs. Linear attenuation coefficients (μ) have been estimated from the use of XCOM code and measured results. Reasonable agreement was attended between theoretical and experimental results. These composites were also found to display excellent percentage of heaviness with respect to other conventional materials.

  1. The effect of polyhedral oligomeric silsesquioxane dispersant and low surface energy additives on spectrally selective paint coatings with self-cleaning properties

    Energy Technology Data Exchange (ETDEWEB)

    Jerman, Ivan; Kozelj, Matjaz; Orel, Boris [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia)

    2010-02-15

    Thickness-Insensitive Spectrally Selective (TISS) paint coatings were made of fluoropolymer resin binder (Lumiflon (LF), Asahi Glass Co., Ltd., Japan) and their water- and oil-repellent properties were obtained (contact angle: {theta}{sub water}{proportional_to}150 , {theta}{sub n-hexadecane}{proportional_to}55 ) by the addition of Polyhedral Oligomeric Silsesquioxane (POSS) characterized by amino (AP), isooctyl (IO) and perfluoro (PF) groups (i.e. AP{sub 2}IO{sub 4}PF{sub 2}) attached on the silsesquioxane cube (-SiO{sub 3/2}){sub 8}. Paint dispersions were made by modifying of black spinel pigment with trisilanol isobutyl (IB{sub 7}T{sub 7}(OH){sub 3}) POSS dispersant and with a single-capped silane isobutyltrimethoxysilane (IBTMS). Infrared and {sup 29}Si NMR spectra measurements were used for the identification of the structural characteristic of the corresponding POSS compounds. Surface free energy values of the pure cross-linked (no pigment added) LF binder which was determined from the measured contact angles for water, diiodomethane and formamide revealed the {gamma}{sup tot} value of the LF unpigmented resin with added AP{sub 2}IO{sub 4}PF{sub 2} T{sub 8} POSS was about 16.4 mN/m, which led to the {theta}{sub water}{proportional_to}110 , indicating enhancement of the hydrophobicity of the pure LF resin binder ({theta}{sub water}{proportional_to}89 ). SEM micrographs, which were used for the assessment of the TISS paint coating surface morphology confirmed the beneficial dispersive effect of IB{sub 7} T{sub 7}(OH){sub 3} dispersant as compared to the IBTMS silane. The presence of large Aluminium flake pigment and finely ground black pigment led to the formation of TISS paint coating surface, which exhibited bi-hierarchical roughness, resulting in water sliding angles of less than 10 , indicating the possible self-cleaning effect ({theta}{sub water}>150 and {theta}{sub n-hexadecane}{proportional_to}55 ). The use of POSS dispersant and POSS low surface energy

  2. Impact of nanoclay dispersed phenol formaldehyde/fumed silica nanocomposites on physico-mechanical and thermal properties

    Science.gov (United States)

    Lai, Josephine Chang Hui; Rahman, Md. Rezaur; Hamdan, Sinin

    2017-12-01

    In this study, the physical, mechanical and thermal properties of phenol formaldehyde/fumed silica/nanoclay (PF/FS/clay) nanocomposites were investigated. PF/FS/clay nanocomposites were prepared via condensation polymerization method and the effect of different clays as compatibilizers were subsequently investigated. The properties of nanocomposites were characterized through Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA) and tensile test. FT-IR results confirmed the condensation polymerization and the formation of nanocomposites. SEM result revealed that the surface-modified clay (1.34TCN) had better compatibility with PF/FS matrix compared to surface-modified clay (1.28E), clay (1.30E) and clay (1.31PS). Besides, clay (1.34TCN)-loaded nanocomposites showed better surface morphology among all the nanocomposites. Furthermore, PF/FS/clay (1.34TCN) nanocomposite exhibited better tensile strength and modulus up to 68% due to the strong interfacial bonding between the polymer matrix and fillers. Thermal stability of PF/FS/clay (1.34TCN) nanocomposite showed the highest weight percent loss at the final degradation stage with higher activation energy. Overall, this study proved that clay (1.34TCN) was the most suitable to be introduced in PF/FS matrix.

  3. Synthesis, structural, optical and electrical properties of metal nanoparticle-rare earth ion dispersed in polymer film

    Science.gov (United States)

    Kumar, Brijesh; Kaur, Gagandeep; Singh, P.; Rai, S. B.

    2013-03-01

    Cu-nanoparticles have been prepared by ablating a copper target submerged in benzene with laser pulses of Nd:YAG (wavelength: 355, 532 nm and 1,064 nm). Colloidal nanoparticles have been characterized by UV-Vis spectroscopy and transmission electron microscopy. The obtained radius for the nanoparticles prepared using 1,064 nm irradiation lies in the range 15-30 nm, with absorption peak at 572 nm. Luminescence properties of Tb3+ ions in the presence and absence of Cu-nanoparticles have been investigated using 355 nm excitation. An enhancement in luminescence of Tb3+ by local field effect causing increase in lifetime of 5D4 level of Tb3+ ion has been observed. Frequency and temperature-dependent conductivity of Tb3+ doped PVA thin films with and without Cu-nanoparticles have been measured in the frequency range 20 Hz-1 MHz and in the temperature range 318-338 K (well below its melting temperature). Real part of the conductivity spectra has been explained in terms of power law. The electrical properties of the thin films show a decrease in dc conductivity on incorporation of the Cu-nanoparticles.

  4. Development of a novel cup cake with unique properties of essential oil of betel leaf (Piper betle L.) for sustainable entrepreneurship.

    Science.gov (United States)

    Roy, Arnab; Guha, Proshanta

    2015-08-01

    Betel vine (Piper betle L.) is a root climber with deep green heart shaped leaves. It belongs to the Piperaceae family. There is a huge wastage of the leaves during glut season and it can be reduced by various means including extraction of medicinal essential oil which can be considered as GRAS (generally recognized as safe) materials. Therefore, attempts were made to develop a novel cup cake by incorporating essential oil of betel leaf. The textural properties of the cakes were measured by texture analyzer instrument; whereas the organoleptic properties were adjudged by human preferences using sensory tables containing 9-point hedonic scale. Price estimation was done considering all costs and charges. Finally, all parameters of the developed cake were compared with different cup cakes available in the market for ascertaining consumer acceptability of the newly developed product in terms of quality and market price. Results revealed that the Novel cup cake developed with 0.005 % (v/w) essential oil of betel leaf occupied the 1st place among the four developed novel cup cakes. However, it occupied 4th place among the nine cup cakes in the overall preference list prepared based on the textural and organoleptic qualities, though its market price was calculated to be comparable to all the leading cupcakes available in the market. This indicates that manufacturing of novel cup cake with essential oil of betel leaf would be a profitable and self-sustaining entrepreneurship.

  5. Ligand design for alkali-metal-templated self-assembly of unique high-nuclearity CuII aggregates with diverse coordination cage units: crystal structures and properties.

    Science.gov (United States)

    Du, Miao; Bu, Xian-He; Guo, Ya-Mei; Ribas, Joan

    2004-03-19

    The construction of two unique, high-nuclearity Cu(II) supramolecular aggregates with tetrahedral or octahedral cage units, [(mu(3)-Cl)[Li subset Cu(4)(mu-L(1))(3)](3)](ClO(4))(8)(H(2)O)(4.5) (1) and [[Na(2) subset Cu(12)(mu-L(2))(8)(mu-Cl)(4)](ClO(4))(8)(H(2)O)(10)(H(3)O(+))(2)](infinity) (2) by alkali-metal-templated (Li(+) or Na(+)) self-assembly, was achieved by the use of two newly designed carboxylic-functionalized diazamesocyclic ligands, N,N'-bis(3-propionyloxy)-1,4-diazacycloheptane (H(2)L(1)) or 1,5-diazacyclooctane-N,N'-diacetate acid (H(2)L(2)). Complex 1 crystallizes in the trigonal R3c space group (a = b = 20.866(3), c = 126.26(4) A and Z = 12), and 2 in the triclinic P1 space group (a = 13.632(4), b = 14.754(4), c = 19.517(6) A, alpha = 99.836(6), beta = 95.793(5), gamma = 116.124(5) degrees and Z = 1). By subtle variation of the ligand structures and the alkali-metal templates, different polymeric motifs were obtained: a dodecanuclear architecture 1 consisting of three Cu(4) tetrahedral cage units with a Li(+) template, and a supramolecular chain 2 consisting of two crystallographically nonequivalent octahedral Cu(6) polyhedra with a Na(+) template. The effects of ligand functionality and alkali metal template ions on the self-assembly processes of both coordination supramolecular aggregates, and their magnetic behaviors are discussed in detail.

  6. Structural and electronic properties of graphene–ZnO interfaces: dispersion-corrected density functional theory investigations

    International Nuclear Information System (INIS)

    Xu Pengtao; Tang Qing; Zhou Zhen

    2013-01-01

    Detailed first-principles computations were performed on the geometric and electronic properties of the interfaces between graphene and ZnO polar surfaces. A notable van der Waals force exists at the interface, and charge transfer occurs between graphene and ZnO as a result of the difference in their work functions. The Dirac point of graphene remains intact despite its adsorption on ZnO, implying that its interaction with ZnO does not affect the superior conductivity of graphene. Excited electrons within the energy range of 0–3 eV (versus Fermi energy) in the hybrid systems are mainly accumulated on graphene. The computations provide a theoretical explanation for the good performance of graphene/ZnO hybrid materials in photocatalysts and solar cells. (paper)

  7. Low percolation transitions in carbon nanotube networks dispersed in a polymer matrix: dielectric properties, simulations and experiments.

    Science.gov (United States)

    Simoes, Ricardo; Silva, Jaime; Vaia, Richard; Sencadas, Vítor; Costa, Pedro; Gomes, João; Lanceros-Méndez, Senentxu

    2009-01-21

    The low concentration behaviour and the increase of the dielectric constant in carbon nanotubes/polymer nanocomposites near the percolation threshold are still not well understood. In this work, a numerical model has been developed which focuses on the effect of the inclusion of conductive fillers in a dielectric polymer matrix on the dielectric constant and the dielectric strength. Experiments have been carried out in carbon nanotubes/poly(vinylidene fluoride) nanocomposites in order to compare to the simulation results. This work shows how the critical concentration is related to the formation of capacitor networks and that these networks give rise to high variations in the electrical properties of the composites. Based on numerical studies, the dependence of the percolation transition on the preparation of the nanocomposite is discussed. Finally, based on numerical and experimental results, both ours and from other authors, the causes of anomalous percolation behaviour of the dielectric constant are identified.

  8. Effect of Li Adsorption on the Electronic and Hydrogen Storage Properties of Acenes: A Dispersion-Corrected TAO-DFT Study

    Science.gov (United States)

    Seenithurai, Sonai; Chai, Jeng-Da

    2016-01-01

    Due to the presence of strong static correlation effects and noncovalent interactions, accurate prediction of the electronic and hydrogen storage properties of Li-adsorbed acenes with n linearly fused benzene rings (n = 3–8) has been very challenging for conventional electronic structure methods. To meet the challenge, we study these properties using our recently developed thermally-assisted-occupation density functional theory (TAO-DFT) with dispersion corrections. In contrast to pure acenes, the binding energies of H2 molecules on Li-adsorbed acenes are in the ideal binding energy range (about 20 to 40 kJ/mol per H2). Besides, the H2 gravimetric storage capacities of Li-adsorbed acenes are in the range of 9.9 to 10.7 wt%, satisfying the United States Department of Energy (USDOE) ultimate target of 7.5 wt%. On the basis of our results, Li-adsorbed acenes can be high-capacity hydrogen storage materials for reversible hydrogen uptake and release at ambient conditions. PMID:27609626

  9. High-water-content mouldable polyvinyl alcohol-borax hydrogels reinforced by well-dispersed cellulose nanoparticles: dynamic rheological properties and hydrogel formation mechanism.

    Science.gov (United States)

    Han, Jingquan; Lei, Tingzhou; Wu, Qinglin

    2014-02-15

    Cellulose nanoparticle (CNP) reinforced polyvinyl alcohol-borax (PB) hydrogels were produced via a facile approach in an aqueous system. The effects of particle size, aspect ratio, crystal structure, and surface charge of CNPs on the rheological properties of the composite hydrogels were investigated. The rheological measurements confirmed the incorporation of well-dispersed CNPs to PB system significantly enhanced the viscoelasticity and stiffness of hydrogels. The obtained free-standing, high elasticity and mouldable hydrogels exhibited self-recovery under continuous step strain and thermo-reversibility under temperature sweep. With the addition of cellulose I nanofibers, a 19-fold increase in the high-frequency plateau of storage modulus was obtained compared with that of the pure PB. CNPs acted as multifunctional crosslinking agents and nanofillers to physically and chemically bridge the 3D network hydrogel. The plausible mechanism for the multi-complexation between CNPs, polyvinyl alcohol and borax was proposed to understand the relationship between the 3D network and hydrogel properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. [The study of antimicrobial properties of silver nanoparticles in the form of a colloidal solution in the matrix of finely dispersed silica].

    Science.gov (United States)

    Korchak, G I; Surmasheva, E V; Mikhienkova, A I; Nikonova, N A; Romanenko, L I; Oliĭnyk, Z A; Gorval', A K; Rosada, M A

    2012-01-01

    In the experimental study obtained with chemical method colloid solution of nanoparticles (NPs) of silver (Ag) and a composite on his base in the matrix of finely dispersed silica with particle size of 8-12 nm and NPs concentration in basic solution of 0,0016% (0,016 mg/cm3) were established to exhibit high antimicrobial activity against the test organisms: E. coli, P. aeruginosa, S. Aureus and C. Albicans, which depended on a set of factors. Antibacterial properties of tissue impregnated with Ag-NPs were studied. As stabilizing substances a mixture of surface-active substance sodium dodecyl sulfate and polymer polyvinylpyrrolidone was used Before the beginning of the study effective neutralizer was tailored. Times of preservation of antimicrobial activity of test samples have been established, and also their stability throughout long term of supervision (24 months) has been shown. Effect of organic pollution on antimicrobal activity of the samples has been studied. Based on obtained results the algorithm of the study of antimicrobial properties of nanopreparations has been elaborated.

  11. Chemical dispersants

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

    2016-01-01

    Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil

  12. Geometry of physical dispersion relations

    International Nuclear Information System (INIS)

    Raetzel, Dennis; Rivera, Sergio; Schuller, Frederic P.

    2011-01-01

    To serve as a dispersion relation, a cotangent bundle function must satisfy three simple algebraic properties. These conditions are derived from the inescapable physical requirements that local matter field dynamics must be predictive and allow for an observer-independent notion of positive energy. Possible modifications of the standard relativistic dispersion relation are thereby severely restricted. For instance, the dispersion relations associated with popular deformations of Maxwell theory by Gambini-Pullin or Myers-Pospelov are not admissible. Dispersion relations passing the simple algebraic checks derived here correspond to physically admissible Finslerian refinements of Lorentzian geometry.

  13. Uniqueness in time measurement

    International Nuclear Information System (INIS)

    Lorenzen, P.

    1981-01-01

    According to P. Janich a clock is defined as an apparatus in which a point ( hand ) is moving uniformly on a straight line ( path ). For the definition of uniformly first the scaling (as a constant ratio of velocities) is defined without clocks. Thereafter the uniqueness of the time measurement can be proved using the prove of scaling of all clocks. But the uniqueness can be defined without scaling, as it is pointed out here. (orig.) [de

  14. The Lyα properties of faint galaxies at z ∼ 2-3 with systemic redshifts and velocity dispersions from Keck-MOSFIRE

    Energy Technology Data Exchange (ETDEWEB)

    Erb, Dawn K. [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States); Steidel, Charles C.; Trainor, Ryan F.; Strom, Allison L.; Konidaris, Nicholas P.; Matthews, Keith [Cahill Center for Astrophysics, California Institute of Technology, 1216 East California Boulevard, MS 249-17, Pasadena, CA 91125 (United States); Bogosavljević, Milan [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia); Shapley, Alice E.; Nestor, Daniel B.; Mace, Gregory; McLean, Ian S. [Department of Physics and Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095 (United States); Kulas, Kristin R. [NASA Ames Research Center, Bldg. 211, Room 112, Moffett Field, CA 94035-1000 (United States); Law, David R. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); Rudie, Gwen C. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Reddy, Naveen A. [Department of Physics and Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521 (United States); Pettini, Max, E-mail: erbd@uwm.edu [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2014-11-01

    We study the Lyα profiles of 36 spectroscopically detected Lyα-emitters (LAEs) at z ∼ 2-3, using Keck MOSFIRE to measure systemic redshifts and velocity dispersions from rest-frame optical nebular emission lines. The sample has a median optical magnitude R=26.0, and ranges from R≃23 to R>27, corresponding to rest-frame UV absolute magnitudes M {sub UV} ≅ –22 to M {sub UV} > –18.2. Dynamical masses range from M {sub dyn} < 1.3 × 10{sup 8} M {sub ☉} to M {sub dyn} = 6.8 × 10{sup 9} M {sub ☉}, with a median value of M {sub dyn} = 6.3 × 10{sup 8} M {sub ☉}. Thirty of the 36 Lyα emission lines are redshifted with respect to the systemic velocity with at least 1σ significance, and the velocity offset with respect to systemic Δv {sub Lyα} is correlated with the R-band magnitude, M {sub UV}, and the velocity dispersion measured from nebular emission lines with >3σ significance: brighter galaxies with larger velocity dispersions tend to have larger values of Δv {sub Lyα}. We also make use of a comparison sample of 122 UV-color-selected R<25.5 galaxies at z ∼ 2, all with Lyα emission and systemic redshifts measured from nebular emission lines. Using the combined LAE and comparison samples for a total of 158 individual galaxies, we find that Δv {sub Lyα} is anti-correlated with the Lyα equivalent width with 7σ significance. Our results are consistent with a scenario in which the Lyα profile is determined primarily by the properties of the gas near the systemic redshift; in such a scenario, the opacity to Lyα photons in lower mass galaxies may be reduced if large gaseous disks have not yet developed and if the gas is ionized by the harder spectrum of young, low metallicity stars.

  15. Preparation, structure, and unique redox properties of mono-, bis-, and Tris(diarylmethylene)-1,3,5-trithianes and related compounds

    Science.gov (United States)

    Suzuki; Yoshino; Nishida; Ohkita; Tsuji

    2000-09-08

    A series of 1,3,5-trithianes 1-3 having diarylmethylene units were designed as novel electron donors giving highly colored cationic species upon oxidation. They were prepared along with the dithiane and dithiazine derivatives 4-6 by the reactions of lithiated heterocycles with diaryl ketones followed by dehydration. Voltammetric analyses indicate that a large structural change and/or transannular bonding are induced during their electrochemical oxidation. Mono(diarylmethylene) derivative 1a exhibits electrochromism with vivid change in color from faintly yellow to deep blue with concomitant rotation around the exocyclic bond. Both of the strongly colored salts obtained upon oxidation of 2,4-bis- and 2,4,6-tris(diarylmethylene)-1,3,5-trithianes (2aa and 3) consist of the dications with a 1,2,4-trithiane ring, suggesting the easy skeletal rearrangement of the transannular dications with a trithiabicylo[3.1.0]hexane ring. Upon reduction of these salts were obtained bright yellow 12 and 13, respectively, with high electron-donating properties due to the tetraarylbutadiene-type conjugation, thus giving another class of electrochromic compounds.

  16. Materials by design--exploiting the unique properties of pulsed laser deposition for the synthesis of novel hard materials and structures

    International Nuclear Information System (INIS)

    Willmott, P.R.; Spillmann, H.

    2002-01-01

    Novel multilayer thin film structures with an (A-B-C-B) four-sublayer periodicity were synthesized using pulsed reactive crossed-beam laser ablation. The layers were based on transition metal carbonitrides in which one sublayer (A=TiC x N 1-x ) was optimized for its high hardness, another (C=ZrC x N 1-x ) for its low frictional properties, and a third (B=VC x N 1-x ) which acted as a barrier to dislocation propagation. Control of growth and stoichiometry was facilitated by using thermally stable gases as sources for the carbon and nitrogen which were activated by collisions with the ablation plasma. It was discovered that the ablation yields of Ti, V, and Zr were almost identical, so that the sublayer thickness was directly proportional to the number of ablated shots per sublayer metal. The four-sublayer structures were harder (H-bar=35 GPa) than corresponding bilayer structures (H-bar=30 GPa) in which the VC x N 1-x sublayers were missing. Further improvements are expected by optimizing the sublayer ratios and the absolute period thickness

  17. Unique Infectious Strategy of H5N1 Avian Influenza Virus Is Governed by the Acid-Destabilized Property of Hemagglutinin.

    Science.gov (United States)

    Daidoji, Tomo; Watanabe, Yohei; Arai, Yasuha; Kajikawa, Junichi; Hirose, Ryohei; Nakaya, Takaaki

    Highly pathogenic avian influenza (HPAI) H5N1 virus emerged in 1997 as a zoonotic disease in Hong Kong. It has since spread to Asia and Europe and is a serious threat to both the poultry industry and human health. For effective surveillance and possible prevention/control of HPAI H5N1 viruses, it is necessary to understand the molecular mechanism underlying HPAI H5N1 pathogenesis. The hemagglutinin (HA) protein of influenza A viruses (IAVs) is one of the major determinants of host adaptation, transmissibility, and viral virulence. The main function of the HA protein is to facilitate viral entry and viral genome release within host cells before infection. To achieve viral infection, IAVs belonging to different subtypes or strains induce viral-cell membrane fusion at different endosomal pH levels after internalization through endocytosis. However, host-specific endosomal pH also affects induction of membrane fusion followed by infection. The HA protein of HPAI H5N1 has a higher pH threshold for membrane fusion than the HA protein of classical avian influenza viruses. Although this particular property of HA (which governs viral infection) is prone to deactivation in the avian intestine or in an ambient environment, it facilitates efficient infection of host cells, resulting in a broad host tropism, regardless of the pH in the host endosome. Accumulated knowledge, together with further research, about the HA-governed mechanism underlying HPAI H5N1 virulence (i.e., receptor tropism and pH-dependent viral-cell membrane fusion) will be helpful for developing effective surveillance strategies and for prevention/control of HPAI H5N1 infection.

  18. Might "Unique" Factors Be "Common"? On the Possibility of Indeterminate Common-Unique Covariances

    Science.gov (United States)

    Grayson, Dave

    2006-01-01

    The present paper shows that the usual factor analytic structured data dispersion matrix lambda psi lambda' + delta can readily arise from a set of scores y = lambda eta + epsilon, shere the "common" (eta) and "unique" (epsilon) factors have nonzero covariance: gamma = Cov epsilon,eta) is not equal to 0. Implications of this finding are discussed…

  19. Unique catalytic properties of a butoxy chain-containing ruthenated porphyrin towards oxidation of uric acid and reduction of dioxygen for visible light-enhanced fuel cells

    International Nuclear Information System (INIS)

    Liu, Junchen; Wang, Yi; Deng, Qiang; Zhu, Licai; Chao, Hui; Li, Hong

    2016-01-01

    Highlights: • Ru(II)PTPP/CdS shows two Ru(II)-based oxidation peaks at 0.296 V and 0.830 V. • Photoelectrocatalytic oxidation of UA exhibits good linear responses. • The butoxy chain endows Ru(II)PTPP with multifunctional catalytic properties. • Ru(II)PTPP on CF electrode can remarkably promote the reduction of oxygen. • The assembled cell has I_S_C of 0.136 mA cm"−"2 and P_m_a_x of 31.50 μW cm"−"2. - Abstract: This paper reports the photoelectrocatalytic activities of a ruthenated porphyrin [Ru(phen)_2(IP-C_4O-TPP)]"2"+ (denoted as Ru(II)PTPP, phen = 1,10-phenanthroline, IP = imidazo[4,5-f][1,10]phenanthroline and TPP = 5,10,15,20-tetraphenylporphyrin) containing a covalently-linked butoxy chain (-C_4O-) between IP and TPP moieties by means of various electrochemical techniques in combination with absorption spectroscopy and scanning electronic microscopy. Ru(II)PTPP is assembled on the surface of CdS nanoparticles, showing two Ru(II)-based peaks at 0.296 V and 0.830 V, where uric acid (UA) can be photoelectrocatalytically oxidized in a linear range of 0.01-10.0 mmol L"−"1. The −C_4O- chain endows the Ru(II)PTPP/carbon felt (CF) electrode with favorable dioxygen (O_2) binding sites to achieve a couple of new redox peaks at −0.213 V, where O_2 involves electrocatalytic reduction reactions. While employing 5.0 mmol L"−"1 UA as fuel, and 60 mL min"−"1 O_2 as oxidant, the proposed photoelectrochemical fuel cell shows open-circuit photovoltage of 0.656 V, short-circuit photocurrent density of 0.136 mA cm"−"2, and maximum power density of 31.50 μW cm"−"2 at 0.497 V under visible-light illumination of 0.18 mW cm"−"2. The present study provides an interesting platform for the utilization of renewable energy sources.

  20. The effect of polymeric excipients on the physical properties and performance of amorphous dispersions: Part I, free volume and glass transition.

    Science.gov (United States)

    Li, Jinjiang; Zhao, Junshu; Tao, Li; Wang, Jennifer; Waknis, Vrushali; Pan, Duohai; Hubert, Mario; Raghavan, Krishnaswamy; Patel, Jatin

    2015-02-01

    To investigate the structural effect of polymeric excipients on the behavior of free volume of drug-polymer dispersions in relation to glass transition. Two drugs (indomethacin and ketoconazole) were selected to prepare amorphous dispersions with PVP, PVPVA, HPC, and HPMCAS through spray drying. The physical attributes of the dispersions were characterized using SEM and PXRD. The free volume (hole-size) of the dispersions along with drugs and polymers was measured using positron annihilation lifetime spectroscopy (PALS). Their glass transition temperatures (Tgs) were determined using DSC and DMA. FTIR spectra were recorded to identify hydrogen bonding in the dispersions. The chain structural difference-flexible (PVP and PVPVA) vs. inflexible (HPC and HPMCAS)-significantly impacts the free volume and Tgs of the dispersions as well as their deviation from ideality. Relative to Tg, free volume seems to be a better measure of hydrogen bonding interaction for the dispersions of PVP, HPC, and HPMCAS. The free volume of polymers and their dispersions in general appears to be related to their conformations in solution. Both the backbone chain rigidity of polymers as well as drug-polymer interaction can impact the free volume and glass transition behaviors of the dispersions.

  1. Low-frequency dielectric dispersion and magnetic properties of La, Gd modified Pb(Fe1/2Ta1/2)O3 multiferroics

    International Nuclear Information System (INIS)

    Choudhury, R.N.P.; Rodriguez, C.; Bhattacharya, P.; Katiyar, R.S.; Rinaldi, C.

    2007-01-01

    Pb(Fe 1/2 Ta 1/2 )O 3 (PFT) modified by rare-earth (La and Gd) ions has been synthesized in a single phase using a double-stage synthesis (i.e., Columbite) technique. Scanning electron micrographs (SEM) of the pellet samples have shown a significant change in their grain size and uniform distribution of Gd/La at the Fe-sites. The room temperature X-ray structural analysis shows that the reported cubic (or tetragonal) structure of PFT has been distorted to a monoclinic system on substitution of La/Gd at the Fe-site. Detailed studies of dielectric properties of the above compound on La/Gd substitution have shown strong dielectric dispersion at low frequency (i.e. relaxor behavior) with drastic change in transition temperature. Magnetic characterization shows that though the PFT sample displays an antiferromagnetic transition at ∼150 K, the rare-earth ions-substituted samples do not. Furthermore, temperature dependence of magnetization measurements shows that spin glass transition observed in PFT at low temperatures (5-20 K) does not exist in the La and Gd substituted PFT. Doping of Gd in PFT increases the sample magnetization, especially at low temperature

  2. Dispersibility of silica fume in mortar and its effect on properties of mortar. Silica fume no bunsan to mortar no shotokusei

    Energy Technology Data Exchange (ETDEWEB)

    Oga, H; Uomoto, T [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science

    1992-08-01

    Effect of silica fume dispersibility on concrete characteristics was discussed. Properties of mortar mixed with silica fume to exhibit compression strength varied with displacement rates, patterns, and mixing time of silica fume. In submerged curing age of 28 days, the compression strength in a mortar mixed with silica fume at 10% was affected only very little by the mixing time for both pelletizing and non-pelletizing types for up to 180 seconds. The strength increased thereafter with the mixing time. The compression strength at 1020 seconds showed higher value by about 150 kgf/cm [sup 2] than when no silica fume is added, with a difference because of patterns disappearing. In the case of a mixing time of 1020 seconds, neutralization depth receives very little effect from a pattern difference, and decreases with increasing displacement rate. Neutralization coefficient of the mortar mixed with silica fume at 10% decreased with the mixing time, and it was possible to suppress the neutralization coefficient to 25% of the case without silica fume addition in a 1020-second mixing. 7 refs., 8 figs., 1 tab.

  3. Quasi-homogenous approximation for description of the properties of dispersed systems. The basic approaches to model hardening processes in nanodispersed silica systems. Part 1. Statical polymer method

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2015-02-01

    Full Text Available The paper deals with possibilities to use quasi-homogenous approximation for discription of properties of dispersed systems. The authors applied statistical polymer method based on consideration of average structures of all possible macromolecules of the same weight. The equiations which allow evaluating many additive parameters of macromolecules and the systems with them were deduced. Statistical polymer method makes it possible to model branched, cross-linked macromolecules and the systems with them which are in equilibrium or non-equilibrium state. Fractal analysis of statistical polymer allows modeling different types of random fractal and other objects examined with the mehods of fractal theory. The method of fractal polymer can be also applied not only to polymers but also to composites, gels, associates in polar liquids and other packaged systems. There is also a description of the states of colloid solutions of silica oxide from the point of view of statistical physics. This approach is based on the idea that colloid solution of silica dioxide – sol of silica dioxide – consists of enormous number of interacting particles which are always in move. The paper is devoted to the research of ideal system of colliding but not interacting particles of sol. The analysis of behavior of silica sol was performed according to distribution Maxwell-Boltzmann and free path length was calculated. Using this data the number of the particles which can overcome the potential barrier in collision was calculated. To model kinetics of sol-gel transition different approaches were studied.

  4. Polythiophene derivative functionalized with disperse red 1 chromophore: Its third-order nonlinear optical properties through Z-scan technique under continuous and femtosecond irradiation

    Science.gov (United States)

    de la Garza-Rubí, R. M. A.; Güizado-Rodríguez, M.; Mayorga-Cruz, D.; Basurto-Pensado, M. A.; Guerrero-Álvarez, J. A.; Ramos-Ortiz, G.; Rodríguez, M.; Maldonado, J. L.

    2015-08-01

    A copolymer of 3-hexylthiophene and thiophene functionalized with disperse red 1, poly(3-HT-co-TDR1), was synthesized. Chemical structure, molecular weight distribution, optical and thermal properties of this copolymer were characterized by NMR, FT-IR, UV-vis, GPC and DSC-TGA. An optical nonlinear analysis by Z-scan method was also performed for both continuous wave (CW) and pulsed laser pumping. In the CW regime the nonlinearities were evaluated in solid films, and a negative nonlinear refractive index in the range 2.7-4.1 × 10-4 cm2/W was obtained. These values are notoriously high and allowed to observe self-defocusing effects at very low laser intensities: below 1 mW. Further, nonlinear self-phase modulation patterns, during laser irradiation, were also observed. In the pulsed excitation the nonlinear response was evaluated in solution resulting in large two-photon absorption cross section of 5725 GM for the whole copolymer chain and with a value of 232 GM per repeated monomeric unit.

  5. Investigation of optical, electrical and magnetic properties of hexagonal NiTiO3 nanoparticles prepared via ultrasonic dispersion techniques for high power applications

    Science.gov (United States)

    Karmakar, Subrata; Manna, Ashis Kumar; Varma, Shikha; Behera, Dhrubananda

    2018-05-01

    Nickel titanate (NiTiO3) nanoparticles were synthesized by ultrasonic dispersion techniques using ethylene glycol monoetheline ether as a solvent. The x-ray diffraction (XRD), Raman, transmission electron micrographs (TEM) exhibit pure phase formation, fine hexagonal nanostructure, agglomerated and inhomogeneous grain growth in nm range (26.5 nm) of as-prepared NiTiO3 nanoparticles. Raman studies on NiTiO3 nanoparticles exposed almost all the active vibrational modes (5Ag + 5Eg) of its crystalline structure. A wide optical band gap (3.02 eV) was observed from UV-DRS spectra which arises from the hybridized Ni- 3d and O- 2p orbitals to the Ti -3d orbitals. The characteristics vibration bands of M-O (Ni–O, and Ti–O) were also analyzed using Fourier Transform Infrared spectrum. The antiferromagnetic (AFM) properties were examined from M-H loop with coercive field 75.02 ± 0.05 Oe and saturation magnetization 0.418 ± 0.05 emu gm‑1. respectively. The dielectrics constant and loss decays with high frequency evaluation and Maxwell–Wagner type of polarization were responsible for its dielectric behavior. The total conductivity was explained using NNH and VRH hopping relaxation model and dc activation energy (0.81 eV) were calculated from Arrhenius plot.

  6. Dispersible crystalline nanobundles of YPO{sub 4} and Ln (Eu, Tb)-doped YPO{sub 4}: rapid synthesis, optical properties and bio-probe applications

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Shafquat, E-mail: shafquatmajeed@gmail.com [Indian Institute of Science, Materials Research Centre (India); Bashir, Mohsin [Indian Institute of Science, Department of Molecular Reproduction, Development and Genetics (MRDG) (India); Shivashankar, S. A. [Indian Institute of Science, Materials Research Centre (India)

    2015-07-15

    Undoped and Ln{sup 3+} (Eu and Tb)-doped crystalline nanobundles of YPO{sub 4} were prepared by a facile microwave-assisted route with water as a solvent and without using any surfactant. TEM investigations reveal that the as-prepared powder consists of lenticular-shaped nanobundles (∼100 nm in diameter) made of very small nanorods with diameter less than 10 nm and length varying from 20 to 50 nm. Each nanorod in turn is single crystalline, as revealed by HRTEM imaging. The as-prepared nanobundles are easily dispersible in various solvents, especially water, without any surface functionalization, which is critical for various bio-probe applications like cell and tissue imaging. The Eu- and Tb-doped YPO{sub 4} nanobundles show good photoluminescence properties and were further evaluated for their use as fluorescent biolabels. Our results show that HeLa cells labelled with Eu- and Tb-doped YPO{sub 4} nanobundles show bright red (Eu) and green (Tb) intracellular luminescence under a confocal microscope. Concentration- and time-dependent MTT cell viability assays show that the nanobundles show low toxicity towards cells which makes them promising in bioimaging field.

  7. UV curable aqueous dispersions for wood coatings

    International Nuclear Information System (INIS)

    Peeters, S.; Bleus, J.P.; Wang, Z.J.; Arceneaux, J. A.; Hall, J.

    1999-01-01

    In this paper the characterisation of aqueous dispersions of UV curable resins is described. Two types of dispersions were used: dispersions that are tacky after water evaporation and tack - free before cure dispersions. The physical and rheological properties of these products have been determined and the performance of these dispersions in various formulations, especially for wood applications has been studied. With these dispersions, it is possible to produce coatings having a good cure speed, good surface hardness and good solvent -, chemical - and water resistance

  8. Pay Dispersion and Performance in Teams

    DEFF Research Database (Denmark)

    Bucciol, Alessandro; Foss, Nicolai J; Piovesan, Marco

    2014-01-01

    Extant research offers conflicting predictions about the effect of pay dispersion on team performance. We collected a unique dataset from the Italian soccer league to study the effect of intra-firm pay dispersion on team performance, under different definitions of what constitutes a "team". This ...

  9. Lattices with unique complements

    CERN Document Server

    Saliĭ, V N

    1988-01-01

    The class of uniquely complemented lattices properly contains all Boolean lattices. However, no explicit example of a non-Boolean lattice of this class has been found. In addition, the question of whether this class contains any complete non-Boolean lattices remains unanswered. This book focuses on these classical problems of lattice theory and the various attempts to solve them. Requiring no specialized knowledge, the book is directed at researchers and students interested in general algebra and mathematical logic.

  10. [Unique properties of highly radioresistant bacteria].

    Science.gov (United States)

    Romanovskaia, V A; Rokitko, P V; Malashenko, Iu R

    2000-01-01

    In connection with the Chernobyl Nuclear Power Plant (ChNPP) accident and the negative ecological after-effects for biota in this zone the interest has arisen to radioresistant bacteria, as to the most dynamic model of the given ecosystem, and to mechanisms which provide resistance of bacteria to ionizing radiation. The analysis of published data has shown that the radioresistant bacteria are not interrelated taxonomically and phylogenetically. The extreme radioresistant bacteria are represented by the Deinococcus species, which form a group phylogenetically close to the line Thermus-Meiothermus. Other radioresistant bacteria are the representatives of the genera Rubrobacter, Methylobacterium, Kocuria, Bacillus and some archebacteria. Data on natural habitats, of radioresistant bacteria are not numerous. In a number of cases it is difficult to distinguish their natural habitats, as they were isolated from the samples which were previously exposed to X-ray or gamma-irradiation, or from the ecosystems with the naturally raised radioactivity. To understand the strategy of survival of radioresistant bacteria, we briefly reviewed the mechanism of action of various species of radiation on cells and macromolecules; physiological signs of the cell damage caused by radiation; mechanisms eliminating (repairing) these damages. More details on mechanisms of the DNA repair in D. radiodurans are described. The extreme resistance of D. radiodurans to the DNA damaging factors is defined by 1) repair mechanisms which fundamentally differ from those in other procaryotes; 2) ability to increase the efficiency of a standard set of the DNA repairing proteins. Literary and own data on the effect of radiation on survival of various groups of bacteria in natural ecosystems are summarized. The ecological consequences of the ChNPP accident for soil bacteria in this region were estimated. The reduction of the number of soil bacteria and recession of microbial diversity under the effect of anthropogenic radiation was shown.

  11. Lagrangian properties of particles in turbulence

    NARCIS (Netherlands)

    Toschi, F.; Bodenschatz, E.

    2009-01-01

    The Lagrangian description of turbulence is characterized by a unique conceptual simplicity and by an immediate connection with the physics of dispersion and mixing. In this article, we report some motivations behind the Lagrangian description of turbulence and focus on the statistical properties of

  12. Dispersion strengthening

    International Nuclear Information System (INIS)

    Scattergood, R.O.; Das, E.S.P.

    1976-01-01

    Using digital computer-based methods, models for dispersion strengthening can now be developed which take into account many of the important effects that have been neglected in the past. In particular, the self interaction of a dislocation can be treated, and a computer simulation method was developed to determine the flow stress of a random distribution of circular, impenetrable obstacles, taking into account all such interactions. The flow stress values depended on the obstacle sizes and spacings, over and above the usual 1/L dependence where L is the average obstacle spacing. From an analysis of the results, it was found that the main effects of the self interactions can be captured in a line tension analogue in which the obstacles appear to be penetrable

  13. Manufacturing and mechanical property test of the large-scale oxide dispersion strengthened martensitic mother tube by hot isostatic pressing and hot extrusion process

    International Nuclear Information System (INIS)

    Narita, Takeshi; Ukai, Shigeharu; Kaito, Takeji; Ohtsuka, Satoshi; Fujiwara, Masayuki

    2003-09-01

    Mass production capability of Oxide Dispersion Strengthened (ODS) ferritic steel cladding (9Cr) is evaluated in the Phase II of the Feasibility Studies on Commercialized Fast Reactor Cycle System. The cost for manufacturing mother tube is a dominant factor in the total cost for manufacturing ODS ferritic cladding. In this study, the large-scale 9Cr-ODS martensitic mother tube was produced by overseas supplier with mass production equipments for commercialized ODS steels. The process of manufacturing the ODS mother tube consists of raw material powder production, mechanical alloying by high energy ball mill, hot isostatic pressing(HIP), and hot extrusion. Following results were obtained in this study. (1) Micro structure of the ODS steels is equivalent to that of domestic products, and fine oxides are uniformly distributed. The mechanical alloying by large capacity (1 ton) ball mill can be satisfactorily carried out. (2) A large scale mother tube (65 mm OD x 48 mm ID x 10,000 mm L), which can produce about 60 pieces of 3 m length ODS ferritic claddings by four times cold rolling, have been successfully manufactured through HIP and Hot Extrusion process. (3) Rough surface of the mother tubes produced in this study can be improved by selecting the reasonable hot extrusion condition. (4) Hardness and tensile strength of the manufactured ODS steels are lower than domestic products with same chemical composition. This is owing to the high aluminum content in the product, and those properties could be improved by decreasing the aluminum content in the raw material powder. (author)

  14. Optical constants, dispersion energy parameters and dielectric properties of ultra-smooth nanocrystalline BiVO4 thin films prepared by rf-magnetron sputtering

    Science.gov (United States)

    Sarkar, S.; Das, N. S.; Chattopadhyay, K. K.

    2014-07-01

    BiVO4 thin films have been prepared through radio frequency (rf) magnetron sputtering of a pre-fabricated BiVO4 target on ITO coated glass (ITO-glass) substrate and bare glass substrates. BiVO4 target material was prepared through solid-state reaction method by heating Bi2O3 and V2O5 mixture at 800 °C for 8 h. The films were characterized by X-ray diffraction, UV-Vis spectroscopy, LCR meter, field emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy. BiVO4 thin films deposited on the ITO-glass substrate are much smoother compared to the thin films prepared on bare glass substrate. The rms surface roughness calculated from the AFM images comes out to be 0.74 nm and 4.2 nm for the films deposited on the ITO-glass substrate and bare glass substrate for the deposition time 150 min respectively. Optical constants and energy dispersion parameters of these extra-smooth BiVO4 thin films have been investigated in detail. Dielectric properties of the BiVO4 thin films on ITO-glass substrate were also investigated. The frequency dependence of dielectric constant of the BiVO4 thin films has been measured in the frequency range from 20 Hz to 2 MHz. It was found that the dielectric constant increased from 145 to 343 at 20 Hz as the film thickness increased from 90 nm to 145 nm (deposition time increased from 60 min to 150 min). It shows higher dielectric constant compared to the literature value of BiVO4.

  15. Layer-by-layer films and colloidal dispersions of graphene oxide nanosheets for efficient control of the fluorescence and aggregation properties of the cationic dye acridine orange.

    Science.gov (United States)

    Hansda, Chaitali; Chakraborty, Utsav; Hussain, Syed Arshad; Bhattacharjee, Debajyoti; Paul, Pabitra Kumar

    2016-03-15

    Chemically derived graphene oxide (GO) nanosheets have received great deal of interest for technological application such as optoelectronic and biosensors. Aqueous dispersions of GO become an efficient template to induce the association of cationic dye namely Acridine Orange (AO). Interactions of AO with colloidal GO was governed by both electrostatic and π-π stacking cooperative interactions. The type of dye aggregations was found to depend on the concentration of GO in the mixed ensemble. Spectroscopic calculations revealed the formation of both H and J-type dimers, but H-type aggregations were predominant. Preparation of layer-by-layer (LbL) electrostatic self-assembled films of AO and GO onto poly (allylamine hydrochloride) (PAH) coated quartz substrate is also reported in this article. UV-Vis absorption, steady state and time resolve fluorescence and Raman spectroscopic techniques have been employed to explore the detail photophysical properties of pure AO, AO/GO mixed solution and AO/GO LbL films. Scanning electron microscopy was also used for visual evidence of the synthesized nanodimensional GO sheets. The fluorescence quenching of AO in the presence of GO in aqueous solution was due to the interfacial photoinduced electron transfer (PET) from photoexcited AO to GO i.e. GO acts as an efficient quenching agent for the fluorescence emission of AO. The quenching is found to be static in nature. Raman spectroscopic results also confirmed the interaction of AO with GO and the electron transfer. The formation of AO/GO complex via very fast excited state electron transfer mechanism may be proposed as to prepare GO-based fluorescence sensor for biomolecular detection without direct labeling the biomolecules by fluorescent probe. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Aggregation dynamics and magnetic properties of magnetic micrometer-sized particles dispersed in a fluid under the action of rotating magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Llera, María [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Codnia, Jorge [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Centro de Investigaciones en Láseres y Aplicaciones, CITEDEF-CONICET, Buenos Aires (Argentina); Jorge, Guillermo A., E-mail: gjorge@ungs.edu.ar [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina)

    2015-06-15

    We present a dynamic study of soft magnetic, commercial Fe and Ni micrometer-sized particles dispersed in oleic acid and subjected to a variable (rotating) magnetic field in the horizontal plane. A very complex structure is formed after the particles decant towards the bottom liquid–solid interface and the magnetic field is applied for several minutes. The dynamics of structure formation was studied by means of the registration and analysis of microscopic video images, through a Matlab image analysis script. Several parameters, such as the number of clusters, the perimeter-based fractal dimension and circularity, were calculated as a function of time. The time evolution of the number of clusters was found to follow a power-law behavior, with an exponent consistent with that found in other studies for magnetic systems, whereas the typical formation time depends on the particle diameter and field configuration. Complementarily, the magnetic properties of the formed structure were studied, reproducing the experiment with liquid paraffin as the containing fluid, and then letting it solidify. The sample obtained was studied by vibrating sample magnetometry. The magnetization curves show that the material obtained is a planar magnetically anisotropic material, which could eventually be used as an anisotropic magnetic sensor or actuator. - Highlights: • Dynamic study of Fe and Ni particles in oleic acid under rotating fields. • A very complex system of interconnected clusters was observed. • Larger particles had a smaller aggregation time. • A power law behavior of the number of clusters vs. time. • A Fe-paraffin sample with planar anisotropy characterized.

  17. A dispersive optical model for n + 120Sn from -15 to +80 MeV and properties of neutron single-particle and single-hole states

    International Nuclear Information System (INIS)

    Chen Zemin; Walter, R L; Tornow, W; Weisel, G J; Howell, C R

    2004-01-01

    Data for σ(θ) and A y (θ) previously obtained at the Triangle Universities Nuclear Laboratory for 120 Sn(n, n) are combined with other measurements of σ(θ) and A y (θ) to create an elastic-scattering database from 9.9 to 24 MeV. In addition, relatively recent high-accuracy measurements of the neutron total cross section σ T for Sn from 5 to 80 MeV are combined with earlier σ T data to form a detailed σ T database from 0.24 to 80 MeV. All of these data are analysed in the framework of a dispersive optical model (DOM). The DOM is extended to negative energies to investigate properties of single-particle and single-hole bound states. The DOM also is used in calculations of compound-nucleus contributions to σ(θ), so that DOM predictions can be compared to σ(θ) measurements. Excellent agreement is obtained for the entire set of scattering data from 0.4 to 24 MeV, and for σ T values from 0.05 to 80 MeV. Calculations of bound-state quantities are compared to values derived from experiment for energies down to -15 MeV. Reasonable agreement for the binding energies is achieved, while the predicted spectroscopic factors disagree somewhat with the values found in stripping and pickup experiments. Finally, the DOM is modified to investigate two features (volume absorption that is asymmetric about the Fermi energy and zero absorption in the vicinity of the Fermi energy) that have been ignored in many DOM models. These modifications have little effect on the agreement of the calculations with the scattering data or with the bound-state quantities

  18. A dispersive optical model for n + {sup 120}Sn from -15 to +80 MeV and properties of neutron single-particle and single-hole states

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zemin [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Walter, R L [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Weisel, G J [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Howell, C R [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

    2004-12-01

    Data for {sigma}({theta}) and A{sub y}({theta}) previously obtained at the Triangle Universities Nuclear Laboratory for {sup 120}Sn(n, n) are combined with other measurements of {sigma}({theta}) and A{sub y}({theta}) to create an elastic-scattering database from 9.9 to 24 MeV. In addition, relatively recent high-accuracy measurements of the neutron total cross section {sigma}{sub T} for Sn from 5 to 80 MeV are combined with earlier {sigma}{sub T} data to form a detailed {sigma}{sub T} database from 0.24 to 80 MeV. All of these data are analysed in the framework of a dispersive optical model (DOM). The DOM is extended to negative energies to investigate properties of single-particle and single-hole bound states. The DOM also is used in calculations of compound-nucleus contributions to {sigma}({theta}), so that DOM predictions can be compared to {sigma}({theta}) measurements. Excellent agreement is obtained for the entire set of scattering data from 0.4 to 24 MeV, and for {sigma}{sub T} values from 0.05 to 80 MeV. Calculations of bound-state quantities are compared to values derived from experiment for energies down to -15 MeV. Reasonable agreement for the binding energies is achieved, while the predicted spectroscopic factors disagree somewhat with the values found in stripping and pickup experiments. Finally, the DOM is modified to investigate two features (volume absorption that is asymmetric about the Fermi energy and zero absorption in the vicinity of the Fermi energy) that have been ignored in many DOM models. These modifications have little effect on the agreement of the calculations with the scattering data or with the bound-state quantities.

  19. Aggregation dynamics and magnetic properties of magnetic micrometer-sized particles dispersed in a fluid under the action of rotating magnetic fields

    International Nuclear Information System (INIS)

    Llera, María; Codnia, Jorge; Jorge, Guillermo A.

    2015-01-01

    We present a dynamic study of soft magnetic, commercial Fe and Ni micrometer-sized particles dispersed in oleic acid and subjected to a variable (rotating) magnetic field in the horizontal plane. A very complex structure is formed after the particles decant towards the bottom liquid–solid interface and the magnetic field is applied for several minutes. The dynamics of structure formation was studied by means of the registration and analysis of microscopic video images, through a Matlab image analysis script. Several parameters, such as the number of clusters, the perimeter-based fractal dimension and circularity, were calculated as a function of time. The time evolution of the number of clusters was found to follow a power-law behavior, with an exponent consistent with that found in other studies for magnetic systems, whereas the typical formation time depends on the particle diameter and field configuration. Complementarily, the magnetic properties of the formed structure were studied, reproducing the experiment with liquid paraffin as the containing fluid, and then letting it solidify. The sample obtained was studied by vibrating sample magnetometry. The magnetization curves show that the material obtained is a planar magnetically anisotropic material, which could eventually be used as an anisotropic magnetic sensor or actuator. - Highlights: • Dynamic study of Fe and Ni particles in oleic acid under rotating fields. • A very complex system of interconnected clusters was observed. • Larger particles had a smaller aggregation time. • A power law behavior of the number of clusters vs. time. • A Fe-paraffin sample with planar anisotropy characterized

  20. Interphase and particle dispersion correlations in polymer nanocomposites

    Science.gov (United States)

    Senses, Erkan

    Particle dispersion in polymer matrices is a major parameter governing the mechanical performance of polymer nanocomposites. Controlling particle dispersion and understanding aging of composites under large shear and temperature variations determine the processing conditions and lifetime of composites which are very important for diverse applications in biomedicine, highly reinforced materials and more importantly for the polymer composites with adaptive mechanical responses. This thesis investigates the role of interphase layers between particles and polymer matrices in two bulk systems where particle dispersion is altered upon deformation in repulsive composites, and good-dispersion of particles is retained after multiple oscillatory shearing and aging cycles in attractive composites. We demonstrate that chain desorption and re-adsorption processes in attractive composites under shear can effectively enhance the bulk microscopic mechanical properties, and long chains of adsorbed layers lead to a denser entangled interphase layer. We further designed experiments where particles are physically adsorbed with bimodal lengths of homopolymer chains to underpin the entanglement effect in interphases. Bimodal adsorbed chains are shown to improve the interfacial strength and used to modulate the elastic properties of composites without changing the particle loading, dispersion state or polymer conformation. Finally, the role of dynamic asymmetry (different mobilities in polymer blends) and chemical heterogeneity in the interphase layer are explored in systems of poly(methyl methacrylate) adsorbed silica nanoparticles dispersed in poly(ethylene oxide) matrix. Such nanocomposites are shown to exhibit unique thermal-stiffening behavior at temperatures above glass transitions of both polymers. These interesting findings suggest that the mobility of the surface-bound polymer is essential for reinforcement in polymer nanocomposites, contrary to existing glassy layer theories

  1. Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Departamento de Física Aplicada, Universidad de Huelva, 21071 Huelva (Spain); Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Mendiboure, B. [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR5150, Université de Pau et des Pays de l’Adour, B. P. 1155, Pau Cedex 64014 (France); Moreno-Ventas Bravo, A. I. [Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Departamento de Geología, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva (Spain)

    2014-11-14

    We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r{sub c} = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r{sub c} = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial

  2. Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

    International Nuclear Information System (INIS)

    Martínez-Ruiz, F. J.; Blas, F. J.; Mendiboure, B.; Moreno-Ventas Bravo, A. I.

    2014-01-01

    We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r c = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r c = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness

  3. Is Life Unique?

    Science.gov (United States)

    Abel, David L.

    2011-01-01

    Is life physicochemically unique? No. Is life unique? Yes. Life manifests innumerable formalisms that cannot be generated or explained by physicodynamics alone. Life pursues thousands of biofunctional goals, not the least of which is staying alive. Neither physicodynamics, nor evolution, pursue goals. Life is largely directed by linear digital programming and by the Prescriptive Information (PI) instantiated particularly into physicodynamically indeterminate nucleotide sequencing. Epigenomic controls only compound the sophistication of these formalisms. Life employs representationalism through the use of symbol systems. Life manifests autonomy, homeostasis far from equilibrium in the harshest of environments, positive and negative feedback mechanisms, prevention and correction of its own errors, and organization of its components into Sustained Functional Systems (SFS). Chance and necessity—heat agitation and the cause-and-effect determinism of nature’s orderliness—cannot spawn formalisms such as mathematics, language, symbol systems, coding, decoding, logic, organization (not to be confused with mere self-ordering), integration of circuits, computational success, and the pursuit of functionality. All of these characteristics of life are formal, not physical. PMID:25382119

  4. Dimensional analysis yields the general second-order differential equation underlying many natural phenomena: the mathematical properties of a phenomenon's data plot then specify a unique differential equation for it.

    Science.gov (United States)

    Kepner, Gordon R

    2014-08-27

    This study uses dimensional analysis to derive the general second-order differential equation that underlies numerous physical and natural phenomena described by common mathematical functions. It eschews assumptions about empirical constants and mechanisms. It relies only on the data plot's mathematical properties to provide the conditions and constraints needed to specify a second-order differential equation that is free of empirical constants for each phenomenon. A practical example of each function is analyzed using the general form of the underlying differential equation and the observable unique mathematical properties of each data plot, including boundary conditions. This yields a differential equation that describes the relationship among the physical variables governing the phenomenon's behavior. Complex phenomena such as the Standard Normal Distribution, the Logistic Growth Function, and Hill Ligand binding, which are characterized by data plots of distinctly different sigmoidal character, are readily analyzed by this approach. It provides an alternative, simple, unifying basis for analyzing each of these varied phenomena from a common perspective that ties them together and offers new insights into the appropriate empirical constants for describing each phenomenon.

  5. Study of mechanical properties of calcium phosphate cement with addition of sodium alginate and dispersant; Estudo das propriedades mecanicas de cimento de fosfato de calcio com adicao de alginato de sodio e defloculante

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.M.; Coelho, W.T.; Thurmer, M.B.; Vieira, P.S.; Santos, L.A., E-mail: julianafernandes2@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRS), RS (Brazil)

    2011-07-01

    Several studies in literature have shown that the addition of polymer additives and deflocculant has a strong influence on the mechanical properties of cements in general.The low mechanical strength is the main impediment to wider use of bone cement of calcium phosphate (CFCs) as the implant material, since they have mechanical strength which equals the maximum of trabecular bone.In order to evaluate the strength of a CFC compound alpha-tricalcium phosphate, sodium alginate were added (1%, 2% and 3% by weight) and dispersant ammonium polyacrylate (3%) in aqueous solution.Specimens were made and evaluated for density, porosity, crystalline phases and mechanical strength.The results show the increase of the mechanical properties of cement when added sodium alginate and dispersant. (author)

  6. Hydrodynamic dispersion

    International Nuclear Information System (INIS)

    Pryce, M.H.L.

    1985-01-01

    A dominant mechanism contributing to hydrodynamic dispersion in fluid flow through rocks is variation of travel speeds within the channels carrying the fluid, whether these be interstices between grains, in granular rocks, or cracks in fractured crystalline rocks. The complex interconnections of the channels ensure a mixing of those parts of the fluid which travel more slowly and those which travel faster. On a macroscopic scale this can be treated statistically in terms of the distribution of times taken by a particle of fluid to move from one surface of constant hydraulic potential to another, lower, potential. The distributions in the individual channels are such that very long travel times make a very important contribution. Indeed, while the mean travel time is related to distance by a well-defined transport speed, the mean square is effectively infinite. This results in an asymmetrical plume which differs markedly from a gaussian shape. The distribution of microscopic travel times is related to the distribution of apertures in the interstices, or in the microcracks, which in turn are affected in a complex way by the stresses acting on the rock matrix

  7. Relativistic plasma dispersion functions

    International Nuclear Information System (INIS)

    Robinson, P.A.

    1986-01-01

    The known properties of plasma dispersion functions (PDF's) for waves in weakly relativistic, magnetized, thermal plasmas are reviewed and a large number of new results are presented. The PDF's required for the description of waves with small wave number perpendicular to the magnetic field (Dnestrovskii and Shkarofsky functions) are considered in detail; these functions also arise in certain quantum electrodynamical calculations involving strongly magnetized plasmas. Series, asymptotic series, recursion relations, integral forms, derivatives, differential equations, and approximations for these functions are discussed as are their analytic properties and connections with standard transcendental functions. In addition a more general class of PDF's relevant to waves of arbitrary perpendicular wave number is introduced and a range of properties of these functions are derived

  8. A facile synthesis approach and impact of shell formation on morphological structure and luminescent properties of aqueous dispersible NaGdF{sub 4}:Yb/Er upconversion nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Anees A., E-mail: aneesaansari@gmail.com [King Saud University, King Abdullah Institute for Nanotechnology (Saudi Arabia); Yadav, Ranvijay; Rai, S. B. [Banaras Hindu University, Department of Physics (India)

    2016-12-15

    A general facile synthesis approach was used for fabrication of highly emissive aqueous dispersible hexagonal phase upconversion luminescent NaGdF{sub 4}:Yb/Er nanorods (core NRs) through metal complex decomposition process. An inert NaGdF{sub 4} and porous silica layers were grafted surrounding the surface of each and every NRs to enhance their luminescence efficiency and colloidal dispersibility in aqueous environment. Optical properties in terms of band gap energy of core, core/shell, and silica-coated core/shell/SiO{sub 2} nanorods were observed to investigate the influence of surface coating, which was gradually decreased after surface coating because of increase crystalline size after growth of inert and silica shells. The inert shell formation before silica surface grafting, upconversion luminescence intensity was greatly improved by about 20 times, owing to the effective surface passivation of the seed core and, therefore, protection of Er{sup 3+} ion in the core from the nonradiative decay caused by surface defects. Moreover, after silica coating, core/shell nanorods shows strong upconversion luminescence property similar to the hexagonal upconversion core NRs. It is expected that these NaGdF{sub 4}:Yb/Er@NaGdF{sub 4}@SiO{sub 2} (core/shell/SiO{sub 2}) NRs including highly upconversion emissive and aqueous dispersible properties make them an ideal materials for various photonic-based potential applications such as in upconversion luminescent bioimaging, magnetic resonance imaging, and photodynamic therapy.

  9. Building unique surface structure on aramid fibers through a green layer-by-layer self-assembly technique to develop new high performance fibers with greatly improved surface activity, thermal resistance, mechanical properties and UV resistance

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Lifang; Yuan, Li; Guan, Qingbao; Gu, Aijuan, E-mail: ajgu@suda.edu.cn; Liang, Guozheng, E-mail: lgzheng@suda.edu.cn

    2017-07-31

    Highlights: • A green technology is setup to build unique surface structure on aramid fiber (AF). • The method is layer-by-layer self-assembling SiO{sub 2} and layered double hydroxide. • The surface of AF is adjustable by controlling the self-assembly cycle number. • New AF has excellent surface activity, anti-UV, thermal and mechanical properties. • The origin behind attractive performances of new AFs was intensively studied. - Abstract: Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of aramid fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO{sub 2} and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91–95%, about 29–14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and

  10. Assessing risk from low energy radionuclide aerosol dispersal

    International Nuclear Information System (INIS)

    Waller, Edward; Perera, Sharman; Erhardt, Lorne; Cousins, Tom; Desrosiers, Marc

    2008-01-01

    Full text: When considering the potential dispersal of radionuclides into the environment, there are two broad classifications: explosive and non-explosive dispersal. An explosive dispersal relies on a violent and sudden release of energy, which may disrupt or vapourised any source containment. As such, the explosion provides the energy to both convert the source into a dispersable physical form and provides initial kinetic energy to transport the source away from the initiation point. This would be the case for sources of radiation in proximity to a steam or chemical explosion of high energy density. A low energy dispersal, on the other hand, may involve a lower energy initiator event (such as a fire or water spray) that transports particles into the near release zone, to be spread via wind or mechanical fields. For this type of dispersion to take place, the source must be in physical form ready for dispersal. In broad terms, this suggests either an ab initio powder form, or soluble/insoluble particulate form in a liquid matrix. This may be the case for radioactive material released from pressurized piping systems, material released through ventilation systems, or deliberate dispersals. To study aerosol dispersion of radionuclides and risk from low energy density initiators, there are a number of important parameters to consider. For example, particle size distribution, physicochemical form, atmospheric effects, charge effects, coagulation and agglomeration. At the University of Ontario Institute of Technology (UOIT) a unique small scale aerosol test chamber has been developed to study the low energy dispersal properties of a number of radioactive source simulant. Principle emphasis has been given to salts (CsCl and CoCl 2 ) and oxides (SrTiO 3 , CeO 2 and EuO 2 ). A planetary ball mill has been utilized to reduce particle size distributions when required. Particle sizing has been performed using Malvern Spraytec spray particle analyzers, cascade impactors, and

  11. Taylor dispersion of nanoparticles

    Science.gov (United States)

    Balog, Sandor; Urban, Dominic A.; Milosevic, Ana M.; Crippa, Federica; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

    2017-08-01

    The ability to detect and accurately characterize particles is required by many fields of nanotechnology, including materials science, nanotoxicology, and nanomedicine. Among the most relevant physicochemical properties of nanoparticles, size and the related surface-to-volume ratio are fundamental ones. Taylor dispersion combines three independent phenomena to determine particle size: optical extinction, translational diffusion, and sheer-enhanced dispersion of nanoparticles subjected to a steady laminar flow. The interplay of these defines the apparent size. Considering that particles in fact are never truly uniform nor monodisperse, we rigorously address particle polydispersity and calculate the apparent particle size measured by Taylor dispersion analysis. We conducted case studies addressing aqueous suspensions of model particles and large-scale-produced "industrial" particles of both academic and commercial interest of various core materials and sizes, ranging from 15 to 100 nm. A comparison with particle sizes determined by transmission electron microscopy confirms that our approach is model-independent, non-parametric, and of general validity that provides an accurate account of size polydispersity—independently on the shape of the size distribution and without any assumption required a priori.

  12. Seed dispersal in fens

    NARCIS (Netherlands)

    Middleton, Beth; van Diggelen, Rudy; Jensen, Kai

    Question: How does seed dispersal reduce fen isolation and contribute to biodiversity? Location: European and North American fens. Methods: This paper reviews the literature on seed dispersal to fens. Results: Landscape fragmentation may reduce dispersal opportunities thereby isolating fens and

  13. Non-contact evaluation of mechanical properties of electroplated wear resistant Ni-P layer from the velocity dispersion of laser SAW; Laser reiki Rayleigh ha no sokudo bunsan wo mochiita taimamo Ni-P mekkiso tokusei no hisesshoku hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Morikawa, Y.; Cho, H.; Takemoto, M. [Aoyama Gakuin University, Tokyo (Japan). Faculty of Science and Engineering; Nakayama, T. [Kobe Steel Ltd., Kobe (Japan)

    1996-11-01

    We developed a new laser surface acoustic wave (SAW) system and applied this to estimate the mechanical properties of the wear-resistant Ni-P layer electroplated on a stainless steel. The velocity dispersions of Rayleigh wave of the as -plated and heat-treated Ni-P layer were obtained by the one point time domain signal processing. The Ni-P layers with excellent wear resistance produced by the heated treatment higher than 725K were found to show higher Rayleigh velocities than that of the substrate steel, while the Ni-P layer with poor wear resistance showed lower velocities. Young`s moduli of the Ni-P layer, estimated so as the computed velocity dispersion agreed with the measured one, increased with the increase of wear resistance. 10 refs., 9 figs., 2 tabs.

  14. Cancer: Unique to Older Adults

    Science.gov (United States)

    ... A to Z › Cancer › Unique to Older Adults Font size A A A Print Share Glossary Unique ... group with other older people with the same type of cancer. Researchers have found that support groups ...

  15. Magnetic effects in anomalous dispersion

    International Nuclear Information System (INIS)

    Blume, M.

    1992-01-01

    Spectacular enhancements of magnetic x-ray scattering have been predicted and observed experimentally. These effects are the result of resonant phenomena closely related to anomalous dispersion, and they are strongest at near-edge resonances. The theory of these resonances will be developed with particular attention to the symmetry properties of the scatterer. While the phenomena to be discussed concern magnetic properties the transitions are electric dipole or electric quadrupole in character and represent a subset of the usual anomalous dispersion phenomena. The polarization dependence of the scattering is also considered, and the polarization dependence for magnetic effects is related to that for charge scattering and to Templeton type anisotropic polarization phenomena. It has been found that the strongest effects occur in rare-earths and in actinides for M shell edges. In addition to the scattering properties the theory is applicable to ''forward scattering'' properties such as the Faraday effect and circular dichroism

  16. A generalized advection dispersion equation

    Indian Academy of Sciences (India)

    This paper examines a possible effect of uncertainties, variability or heterogeneity of any dynamic system when being included in its evolution rule; the notion is illustrated with the advection dispersion equation, which describes the groundwater pollution model. An uncertain derivative is defined; some properties of.

  17. Narrow-gap physical vapour deposition synthesis of ultrathin SnS1-xSex (0 ≤ x ≤ 1) two-dimensional alloys with unique polarized Raman spectra and high (opto)electronic properties.

    Science.gov (United States)

    Gao, Wei; Li, Yongtao; Guo, Jianhua; Ni, Muxun; Liao, Ming; Mo, Haojie; Li, Jingbo

    2018-05-10

    Here we report ultrathin SnS1-xSex alloyed nanosheets synthesized via a narrow-gap physical vapour deposition approach. The SnS1-xSex alloy presents a uniform quadrangle shape with a lateral size of 5-80 μm and a thickness of several nanometers. Clear orthorhombic symmetries and unique in-plane anisotropic properties of the 2D alloyed nanosheets were found with the help of X-ray diffraction, high resolution transmission electron microscopy and polarized Raman spectroscopy. Moreover, 2D alloyed field-effect transistors were fabricated, exhibiting a unipolar p-type semiconductor behavior. This study also provided a lesson that the thickness of the alloyed channels played the major role in the current on/off ratio, and the high ratio of 2.10 × 102 measured from a large ultrathin SnS1-xSex device was two orders of magnitude larger than that of previously reported SnS, SnSe nanosheet based transistors because of the capacitance shielding effect. Obviously enhanced Raman peaks were also found in the thinner nanosheets. Furthermore, the ultrathin SnS0.5Se0.5 based photodetector showed a highest responsivity of 1.69 A W-1 and a short response time of 40 ms under illumination of a 532 nm laser from 405 to 808 nm. Simultaneously, the corresponding highest external quantum efficiency of 392% and detectivity of 3.96 × 104 Jones were also achieved. Hopefully, the narrow-gap synthesis technique provides us with an improved strategy to obtain large ultrathin 2D nanosheets which may tend to grow into thicker ones for stronger interlayer van der Waals forces, and the enhanced physical and (opto)electrical performances in the obtained ultrathin SnS1-xSex alloyed nanosheets prove their great potential in the future applications for versatile devices.

  18. Pay Dispersion and Performance in Teams

    Science.gov (United States)

    Bucciol, Alessandro; Foss, Nicolai J.; Piovesan, Marco

    2014-01-01

    Extant research offers conflicting predictions about the effect of pay dispersion on team performance. We collected a unique dataset from the Italian soccer league to study the effect of intra-firm pay dispersion on team performance, under different definitions of what constitutes a “team”. This peculiarity of our dataset can explain the conflicting evidence. Indeed, we also find positive, null, and negative effects of pay dispersion on team performance, using the same data but different definitions of team. Our results show that when the team is considered to consist of only the members who directly contribute to the outcome, high pay dispersion has a detrimental impact on team performance. Enlarging the definition of the team causes this effect to disappear or even change direction. Finally, we find that the detrimental effect of pay dispersion is due to worse individual performance, rather than a reduction of team cooperation. PMID:25397615

  19. In vitro characterization of a novel polymeric system for preparation of amorphous solid drug dispersions.

    Science.gov (United States)

    Mahmoudi, Zahra N; Upadhye, Sampada B; Ferrizzi, David; Rajabi-Siahboomi, Ali R

    2014-07-01

    Preparation of amorphous solid dispersions using polymers is a commonly used formulation strategy for enhancing the solubility of poorly water-soluble drugs. However, often a single polymer may not bring about a significant enhancement in solubility or amorphous stability of a poorly water-soluble drug. This study describes application of a unique and novel binary polymeric blend in preparation of solid dispersions. The objective of this study was to investigate amorphous solid dispersions of glipizide, a BCS class II model drug, in a binary polymeric system of polyvinyl acetate phthalate (PVAP) and hypromellose (hydroxypropyl methylcellulose, HPMC). The solid dispersions were prepared using two different solvent methods: rotary evaporation (rotavap) and fluid bed drug layering on sugar spheres. The performance and physical stability of the dispersions were evaluated with non-sink dissolution testing, powder X-ray diffraction (PXRD), and modulated differential scanning calorimetry (mDSC). PXRD analysis demonstrated an amorphous state for glipizide, and mDSC showed no evidence of phase separation. Non-sink dissolution testing in pH 7.5 phosphate buffer indicated more than twofold increase in apparent solubility of the drug with PVAP-HPMC system. The glipizide solid dispersions demonstrated a high glass transition temperature (Tg) and acceptable chemical and physical stability during the stability period irrespective of the manufacturing process. In conclusion, the polymeric blend of PVAP-HPMC offers a unique formulation approach for developing amorphous solid dispersions with the flexibility towards the use of these polymers in different ratios and combined quantities depending on drug properties.

  20. Quantum optical rotatory dispersion

    Science.gov (United States)

    Tischler, Nora; Krenn, Mario; Fickler, Robert; Vidal, Xavier; Zeilinger, Anton; Molina-Terriza, Gabriel

    2016-01-01

    The phenomenon of molecular optical activity manifests itself as the rotation of the plane of linear polarization when light passes through chiral media. Measurements of optical activity and its wavelength dependence, that is, optical rotatory dispersion, can reveal information about intricate properties of molecules, such as the three-dimensional arrangement of atoms comprising a molecule. Given a limited probe power, quantum metrology offers the possibility of outperforming classical measurements. This has particular appeal when samples may be damaged by high power, which is a potential concern for chiroptical studies. We present the first experiment in which multiwavelength polarization-entangled photon pairs are used to measure the optical activity and optical rotatory dispersion exhibited by a solution of chiral molecules. Our work paves the way for quantum-enhanced measurements of chirality, with potential applications in chemistry, biology, materials science, and the pharmaceutical industry. The scheme that we use for probing wavelength dependence not only allows one to surpass the information extracted per photon in a classical measurement but also can be used for more general differential measurements. PMID:27713928

  1. Liquid agents for dispersion of hard alloys

    International Nuclear Information System (INIS)

    Putintseva, M.N.

    2006-01-01

    Effects of dispersant properties on granulometric, chemical, and phase composition of the products of WC hard alloy electroerosion are considered. It is established that an increase of liquid dispersant permittivity results in enhanced powder dispersity, and an increase of boiling temperature and kinematic viscosity of a hydrocarbon liquid promotes a carbon loss from WC and intensifies pyrolysis of the liquid.On electroerosion of WC base hard alloy in oil a powder particle consists of b-WC+W 2 C phases, in kerosine - of a-WC+b-WC, in distilled water - of W+W 2 C. The viscosity of liquid dispersants practically has no effect on powder particle size [ru

  2. Application of elastic wave dispersion relations to estimate thermal properties of nanoscale wires and tubes of varying wall thickness and diameter

    International Nuclear Information System (INIS)

    Bifano, Michael F P; Kaul, Pankaj B; Prakash, Vikas

    2010-01-01

    This paper reports dependency of specific heat and ballistic thermal conductance on cross-sectional geometry (tube versus rod) and size (i.e., diameter and wall thickness), in free-standing isotropic non-metallic crystalline nanostructures. The analysis is performed using dispersion relations found by numerically solving the Pochhammer-Chree frequency equation for a tube. Estimates for the allowable phonon dispersion relations within the crystal lattice are obtained by modifying the elastic acoustic dispersion relations so as to account for the discrete nature of the material's crystal lattice. These phonon dispersion relations are then used to evaluate the specific heat and ballistic thermal conductance in the nanostructures as a function of the nanostructure geometry and size. Two major results are revealed in the analysis: increasing the outer diameter of a nanotube while keeping the ratio of the inner to outer tube radius (γ) fixed increases the total number of available phonon modes capable of thermal population. Secondly, decreasing the wall thickness of a nanotube (i.e., increasing γ) while keeping its outer diameter fixed, results in a drastic decrease in the available phonon mode density and a reduction in the frequency of the longitudinal and flexural acoustic phonon modes in the nanostructure. The dependency of the nanostructure's specific heat on temperature indicates 1D, 2D, and 3D geometric phonon confinement regimes. Transition temperatures for each phonon confinement regime are shown to depend on both the nanostructure's wall thickness and outer radius. Compared to nanowires (γ = 0), the frequency reduction of acoustic phonon modes in thinner walled nanotubes (γ = 0.96) is shown to elevate the ballistic thermal conductance of the thin-walled nanotube between 0.2 and 150 K. At 20 K, the ballistic thermal conductance of the thin-walled nanotube (γ = 0.96) becomes 300% greater than that of a solid nanowire. For temperatures above 150 K, the trend

  3. The effect of the presence of alcohol in the dispersing phase of oxide sols on the properties of RuO2-TiO2/Ti anodes obtained by the sol–gel procedure

    Directory of Open Access Journals (Sweden)

    R. ATANASOSKI

    2000-09-01

    Full Text Available The effect of the addition of ethanol and 2-propanol to the dispersing phase of TiO2 and RuO2 sols mixture on the morphology and, consequently, on the electrochemical properties of the sol-gel obtained activated titanium anodes was investigated. The properties of the obtained anodes were compared to those obtained by the thermal decomposition of appropriate chloride salts. The morphology of the anode coatings was examined by scanning tunneling microscopy. The electrochemical behaviour was investigated by cyclic voltammetry and by polarization measurements. An accelerated stability test was used for the examination of the stability of the anodes under simultaneous oxygen and chlorine evolution reaction. A dependence of the anode stability on the type of added alcohol is indicated.

  4. Single-particle dispersion in compressible turbulence

    Science.gov (United States)

    Zhang, Qingqing; Xiao, Zuoli

    2018-04-01

    Single-particle dispersion statistics in compressible box turbulence are studied using direct numerical simulation. Focus is placed on the detailed discussion of effects of the particle Stokes number and turbulent Mach number, as well as the forcing type. When solenoidal forcing is adopted, it is found that the single-particle dispersion undergoes a transition from the ballistic regime at short times to the diffusive regime at long times, in agreement with Taylor's particle dispersion argument. The strongest dispersion of heavy particles is announced when the Stokes number is of order 1, which is similar to the scenario in incompressible turbulence. The dispersion tends to be suppressed as the Mach number increases. When hybrid solenoidal and compressive forcing at a ratio of 1/2 is employed, the flow field shows apparent anisotropic property, characterized by the appearance of large shock wave structures. Accordingly, the single-particle dispersion shows extremely different behavior from the solenoidal forcing case.

  5. Fabrication and Enhanced Thermoelectric Properties of Alumina Nanoparticle-Dispersed Bi0.5Sb1.5Te3 Matrix Composites

    Directory of Open Access Journals (Sweden)

    Kyung Tae Kim

    2013-01-01

    Full Text Available Alumina nanoparticle-dispersed bismuth-antimony-tellurium matrix (Al2O3/BST composite powders were fabricated by using ball milling process of alumina nanoparticle about 10 nm and p-type bismuth telluride nanopowders prepared from the mechanochemical process (MCP. The fabricated Al2O3/BST composite powders were a few hundreds of nanometer in size, with a clear Bi0.5Sb1.5Te3 phase. The composite powders were consolidated into p-type bulk composite by spark plasma sintering process. High-resolution TEM images reveal that alumina nanoparticles were dispersed among the grain boundary or in the matrix grain. The sintered 0.3 vol.% Al2O3/BST composite exhibited significantly improved power factor and reduced thermal conductivity in the temperature ranging from 293 to 473 K compared to those of pure BST. From these results, the highly increased ZT value of 1.5 was obtained from 0.3 vol.% Al2O3/BST composite at 323 K.

  6. Phosphonium–based ionic liquid as dispersing agent for MWCNT in melt-mixing polystyrene blends: Rheology, electrical properties and EMI shielding effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Soares da Silva, Jéssica P. [Universidade Federal do Rio de Janeiro, Instituto de Macromoléculas, 21941-598, Rio de Janeiro (Brazil); Soares, Bluma G., E-mail: bluma@metalmat.ufrj.br [Universidade Federal do Rio de Janeiro, Instituto de Macromoléculas, 21941-598, Rio de Janeiro (Brazil); Universidade Federal do Rio de Janeiro, Programa de Engenharia Metalurgica e de Materiais - COPPE, Centro de Tecnologia, 21941-972, Rio de Janeiro (Brazil); Livi, Sebastien [Université de Lyon, F-69003, Lyon (France); INSA Lyon, F-69621, Villeurbanne (France); CNRS, UMR 5223, Ingénierie des Matériaux Polymères (France); Barra, Guilherme M.O. [Universidade Federal de Santa Catarina, Departamento de Engenharia Mecânica, Florianópolis, SC (Brazil)

    2017-03-01

    Conducting nanocomposites composed with polystyrene (PS) and multi-walled carbon nanotubes (MWCNT) were prepared by melt mixing procedure assisted by trihexyl-(tetradecyl)-phosphonium combined with bis(trifluoromethylsulfonyl) amide counteranion (TFSI) as the ionic liquid (IL). The non-covalent functionalization of MWCNT with the IL was confirmed by Raman spectroscopy and thermogravimetric analysis. The functionalized MWCNT provided better dispersion of the MWCNT within PS matrix, as indicated by transmission electron microscopy (TEM), and also an electrical conductivity as high as 10{sup −1} S/m with 0.66 m% of MWCNT combined with 3.34 m% of IL. This value is around four orders of magnitude higher when compared to nanocomposites with similar amount of untreated MWCNT. From rheological studies, it was observed that the transition between liquid-like to solid-like behavior occurred at lower frequencies for the systems containing functionalized MWCNT. Moreover, an improvement of around 170% in the electromagnetic interference shielding effectiveness (EMI SE) in the X-band frequency range was observed for the nanocomposites containing 1% of MWCNT non-covalently functionalized with the IL, that is, 1% of MWCNT and 5% of IL. - Highlights: • MWCNT well dispersed in PS matrix, in the presence of ionic liquid. • Outstanding electric conductivity of PS/MWCNT nanocomposite. • Improved EMI shielding effectiveness by addition of ionic liquid in PS/MWCNT nanocomposite.

  7. The influence of interfacial defect-region on the thermoelectric properties of nanodiamond-dispersed Bi2Te2.7Se0.3 matrix composites

    Science.gov (United States)

    Min, Tae Sik; Kim, Kyung Tae; Son, Injoon

    2017-09-01

    Nanodiamond-dispersed Bi2Te2.7Se0.3 (ND/BTSe) matrix composites were fabricated by a high energy ball milling followed by spark plasma sintering process. The fabricated ND/BTSe composites show that ND powders with 5 nm in size are dispersed in the BTSe matrix grain rather than agglomerated at the grain boundary. It was found that atomically disordered-lattice structure present nearby the newly formed ND/BTSe interfaces. This interfacial region artificially formed by addition of ND powders plays a role as atomic-scaled defects increasing electron concentration. Electric conductivities of all the ND/BTSe composites show significantly increased values compared to that of pure BTSe in the temperature range from 298 K to 473 K. However, total thermal conductivity of the composites exhibit higher values than the BTSe due to superior electric conductivity even though active lattice phonon scattering at the interfaces affect lowering thermal conductivity. The maximum ZT, 0.97 was obtained from 0.5vol%ND/BTSe composite at 473 K and enhancement in ZT values was clearly revealed above 348 K. Therefore, these results elucidate that addition of ND powders into n-type BTSe matrix is promising method to improve thermoelectric performances.

  8. Effect of TMP variables upon structure and properties in ODS alloy HDA 8077 sheet. [ThermoMechanical Processing of Oxide Dispersion Strengthened nickel alloy

    Science.gov (United States)

    Rothman, M. F.; Tawancy, H. M.

    1980-01-01

    The effects of oxide content level and variations in thermomechanical processing upon the final structure and properties of HDA 8077 sheet have been systematically examined. It was found that creep strength and formability are substantially influenced by both oxide content and TMP schedule. Variations in creep properties obtained appear to correlate with observed microstructures.

  9. A unique theory of all forces

    International Nuclear Information System (INIS)

    Di Vecchia, Paolo

    1997-01-01

    In discussing the construction of a consistent theory of quantum gravity unified with the gauge interactions we are naturally led to a string theory. We review its properties and the five consistent supersymmetric string theories in ten dimensions. We finally discuss the evidence that these theories are actually special limits of a unique 11-dimensional theory, called M-theory, and a recent conjecture for its explicit formulation as a supersymmetric Matrix theory

  10. Clock synchronization and dispersion

    International Nuclear Information System (INIS)

    Giovannetti, Vittorio; Lloyd, Seth; Maccone, Lorenzo; Wong, Franco N C

    2002-01-01

    We present a method to defeat effects of dispersion of timing signals when synchronizing clocks. It is based on the recently proposed 'conveyor belt synchronization' scheme and on the quantum dispersion cancellation effect

  11. Global Properties of M31’s Stellar Halo from the SPLASH Survey. III. Measuring the Stellar Velocity Dispersion Profile

    Science.gov (United States)

    Gilbert, Karoline M.; Tollerud, Erik; Beaton, Rachael L.; Guhathakurta, Puragra; Bullock, James S.; Chiba, Masashi; Kalirai, Jason S.; Kirby, Evan N.; Majewski, Steven R.; Tanaka, Mikito

    2018-01-01

    We present the velocity dispersion of red giant branch stars in M31’s halo, derived by modeling the line-of-sight velocity distribution of over 5000 stars in 50 fields spread throughout M31’s stellar halo. The data set was obtained as part of the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo (SPLASH) Survey, and covers projected radii of 9 to 175 kpc from M31’s center. All major structural components along the line of sight in both the Milky Way (MW) and M31 are incorporated in a Gaussian Mixture Model, including all previously identified M31 tidal debris features in the observed fields. The probability that an individual star is a constituent of M31 or the MW, based on a set of empirical photometric and spectroscopic diagnostics, is included as a prior probability in the mixture model. The velocity dispersion of stars in M31’s halo is found to decrease only mildly with projected radius, from 108 km s‑1 in the innermost radial bin (8.2 to 14.1 kpc) to ∼80 to 90 km s‑1 at projected radii of ∼40–130 kpc, and can be parameterized with a power law of slope ‑0.12 ± 0.05. The quoted uncertainty on the power-law slope reflects only the precision of the method, although other sources of uncertainty we consider contribute negligibly to the overall error budget. The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  12. Dispersing powders in liquids

    CERN Document Server

    Nelson, RD

    1988-01-01

    This book provides powder technologists with laboratory procedures for selecting dispersing agents and preparing stable dispersions that can then be used in particle size characterization instruments. Its broader goal is to introduce industrial chemists and engineers to the phenomena, terminology, physical principles, and chemical considerations involved in preparing and handling dispersions on a commercial scale. The book introduces novices to: - industrial problems due to improper degree of dispersion; - the nomenclature used in describing particles; - the basic physica

  13. Adsorption of an anionic dispersant on lignite

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, R.; Kucukbayrak, S. [Istanbul Technical University, Istanbul (Turkey). Dept. of Chemical Engineering, Chemical & Metallurgical Engineering Faculty

    2001-12-01

    Since coal is not a homogeneous substance but a mixture of carbonaceous materials and mineral matter, it has a variety of surface properties. Therefore, it is not easy to control the properties of coal suspensions by simply adjusting variables, such as pH and/or electrolyte. A chemical agent needs to be added to control the properties of the coal suspensions. The adsorption behavior of an anionic dispersant in the presence of a wetting agent using some Turkish lignite samples was investigated. The effects of dispersant concentration, temperature and pH on the dispersant adsorption were studied systematically, and the experimental results are presented. Pellupur B69 as a dispersant, commercial mixture of formaldehyde condensate sodium salt of naphthalene sulphonic acid, and Texapon N{sub 2}5 as a wetting agent, a sodium lauryl ether sulfate, have been used.

  14. Dispersion of Bed Load Particles

    OpenAIRE

    SAWAI, Kenji

    1987-01-01

    The motion of bed load particles is so irregular that they disperse remarkably with time.In this study, some flume tests using painted tracer particles were carried out, in which thedispersive property of tracers changed variously with sediment feed rate.In analysing this process, a stochastic simulation model is proposed where it is discussedabout the degree of exposure of individual particle near the bed surface and about the variationof its pick up rate. The exponential distribution of ste...

  15. Diabetes: Unique to Older Adults

    Science.gov (United States)

    ... Stroke Urinary Incontinence Related Documents PDF Choosing Wisely: Diabetes Tests and Treatments Download Related Video Join our e-newsletter! Aging & Health A to Z Diabetes Unique to Older Adults This section provides information ...

  16. Theory of dispersive microlenses

    Science.gov (United States)

    Herman, B.; Gal, George

    1993-01-01

    A dispersive microlens is a miniature optical element which simultaneously focuses and disperses light. Arrays of dispersive mircolenses have potential applications in multicolor focal planes. They have a 100 percent optical fill factor and can focus light down to detectors of diffraction spot size, freeing up areas on the focal plane for on-chip analog signal processing. Use of dispersive microlenses allows inband color separation within a pixel and perfect scene registration. A dual-color separation has the potential for temperature discrimination. We discuss the design of dispersive microlenses and present sample results for efficient designs.

  17. Nanostructured hybrid materials from aqueous polymer dispersions.

    Science.gov (United States)

    Castelvetro, Valter; De Vita, Cinzia

    2004-05-20

    Organic-inorganic (O-I) hybrids with well-defined morphology and structure controlled at the nanometric scale represent a very interesting class of materials both for their use as biomimetic composites and because of their potential use in a wide range of technologically advanced as well as more conventional application fields. Their unique features can be exploited or their role envisaged as components of electronic and optoelectronic devices, in controlled release and bioencapsulation, as active substrates for chromatographic separation and catalysis, as nanofillers for composite films in packaging and coating, in nanowriting and nanolithography, etc. A synergistic combination or totally new properties with respect to the two components of the hybrid can arise from nanostructuration, achieved by surface modification of nanostructures, self-assembling or simply heterophase dispersion. In fact, owing to the extremely large total surface area associated with the resulting morphologies, the interfacial interactions can deeply modify the bulk properties of each component. A wide range of starting materials and of production processes have been studied in recent years for the controlled synthesis and characterization of hybrid nanostructures, from nanoparticle or lamellar dispersions to mesoporous materials obtained from templating nanoparticle dispersions in a continuous, e.g. ceramic precursor, matrix. This review is aimed at giving some basic definitions of what is intended as a hybrid (O-I) material and what are the main synthetic routes available. The various methods for preparing hybrid nanostructures and, among them, inorganic-organic or O-I core-shell nanoparticles, are critically analyzed and classified based on the reaction medium (aqueous, non-aqueous), and on the role it plays in directing the final morphology. Particular attention is devoted to aqueous systems and water-borne dispersions which, in addition to being environmentally more acceptable or even a

  18. Dispersion of multi-walled carbon nanotubes in biocompatible dispersants

    International Nuclear Information System (INIS)

    Piret, J.-P.; Detriche, S.; Vigneron, R.; Vankoningsloo, S.; Rolin, S.; Mejia Mendoza, J. H.; Masereel, B.; Lucas, S.; Delhalle, J.; Luizi, F.; Saout, C.; Toussaint, O.

    2010-01-01

    Owing to their phenomenal electrical and mechanical properties, carbon nanotubes (CNT) have been an area of intense research since their discovery in 1991. Different applications for these nanoparticles have been proposed, among others, in electronics and optics but also in the medical field. In parallel, emerging studies have suggested potential toxic effects of CNT while others did not, generating some conflicting outcomes. These discrepancies could be, in part, due to different suspension approaches used and to the agglomeration state of CNT in solution. In this study, we described a standardized protocol to obtain stable CNT suspensions, using two biocompatible dispersants (Pluronic F108 and hydroxypropylcellulose) and to estimate the concentration of CNT in solution. CNT appear to be greatly individualized in these two dispersants with no detection of remaining bundles or agglomerates after sonication and centrifugation. Moreover, CNT remained perfectly dispersed when added to culture medium used for in vitro cell experiments. We also showed that Pluronic F108 is a better dispersant than hydroxypropylcellulose. In conclusion, we have developed a standardized protocol using biocompatible surfactants to obtain reproducible and stable multi-walled carbon nanotubes suspensions which can be used for in vitro or in vivo toxicological studies.

  19. Properties of An Oral Nanoformulation of A Molecularly Dispersed Amphotericin B Comprising A Composite Matrix of Theobroma Oil and Bee’S Wax

    Directory of Open Access Journals (Sweden)

    Chloe See Wei Tan

    2014-12-01

    Full Text Available An amphotericin B-containing (AmB solid lipid nanoparticulate drug delivery system intended for oral administration, comprised of bee’s wax and theobroma oil as lipid components was formulated with the aim to ascertain the location of AmB within the lipid matrix: (a a homogenous matrix; (b a drug-enriched shell; or (c a drug enriched core. Both the drug-loaded and drug-free nanoparticles were spherical with AmB contributing to an increase in both the z-average diameter (169 ± 1 to 222 ± 2 nm and zeta potential (40.8 ± 0.9 to 50.3 ± 1.0 mV of the nanoparticles. A maximum encapsulation efficiency of 21.4% ± 3.0%, corresponding to 10.7 ± 0.4 mg encapsulated AmB within the lipid matrix was observed. Surface analysis and electron microscopic imaging indicated that AmB was dispersed uniformly within the lipid matrix (option (a above and, therefore, this is the most suitable of the three models with regard to modeling the propensity for uptake by epithelia and release of AmB in lymph.

  20. Effect of Ga2O3 Nanoparticles Dispersion on Microstructure and Thermoelectric Properties of p-Type BiSbTe Based Alloys

    Directory of Open Access Journals (Sweden)

    Kim E.-B.

    2017-06-01

    Full Text Available In this study, p-type Bi0.5Sb1.5Te3 based nanocomposites with addition of different weight percentages of Ga2O3 nanoparticles are fabricated by mechanical milling and spark plasma sintering. The fracture surfaces of all Bi0.5Sb1.5Te3 nanocomposites exhibited similar grain distribution on the entire fracture surface. The Vickers hardness is improved for the Bi0.5Sb1.5Te3 nanocomposites with 6 wt% added Ga2O3 due to exhibiting fine microstructure, and dispersion strengthening mechanism. The Seebeck coefficient of Bi0.5Sb1.5Te3 nanocomposites are significantly improved owing to the decrease in carrier concentration. The electrical conductivity is decreased rapidly upon the addition of Ga2O3 nanoparticle due to increasing carrier scattering at newly formed interfaces. The peak power factor of 3.24 W/mK2 is achieved for the base Bi0.5Sb1.5Te3 sintered bulk. The Bi0.5Sb1.5Te3 nanocomposites show low power factor than base sample due to low electrical conductivity.

  1. Dynamics of Dispersive Wave Generation in Gas-Filled Photonic Crystal Fiber with the Normal Dispersion

    Directory of Open Access Journals (Sweden)

    Zhixiang Deng

    2017-01-01

    Full Text Available The absence of Raman and unique pressure-tunable dispersion is the characteristic feature of gas-filled photonic crystal fiber (PCF, and its zero dispersion points can be extended to the near-infrared by increasing gas pressure. The generation of dispersive wave (DW in the normal group velocity dispersion (GVD region of PCF is investigated. It is demonstrated that considering the self-steepening (SS and introducing the chirp of the initial input pulse are two suitable means to control the DW generation. The SS enhances the relative average intensity of blue-shift DW while weakening that of red-shift DW. The required propagation distance of DW emission is markedly varied by introducing the frequency chirp. Manipulating DW generation in gas-filled PCF by the combined effects of either SS or chirp and three-order dispersion (TOD provides a method for a concentrated transfer of energy into the targeted wavelengths.

  2. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    Czech Academy of Sciences Publication Activity Database

    Soltani, A.; Stolz, A.; Charrier, J.; Mattalah, M.; Gerbedoen, J.-C.; Barkad, H.A.; Mortet, Vincent; Rousseau, M.; Bourzgui, N.; BenMoussa, A.; De Jaeger, J.-C.

    2014-01-01

    Roč. 115, č. 16 (2014), "163515-1"-"163515-6" ISSN 0021-8979 Institutional support: RVO:68378271 Keywords : III-V semiconductors * AlN films * surface scattering * refractive index * optical properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2014

  3. The dispersion of SWCNTs treated by coupling and dispersing agents in fiber reinforced polymer composities

    Science.gov (United States)

    Duan, Yuexin; Yuan, Lu; Zhao, Yan; Guan, Fengxia

    2007-07-01

    It is an obstacle issue for Carbon nanotubes (CNTs) applied in fiber reinforced polymer composites that CNTs is dispersed in nano-level, particularly for single-wall Carbon nanotubes (SWCNTs). In this paper, SWCNTs were treated by the coupling agent like volan and dispersing agent as BYK to improve the dispersion in the Glass Fiber/Epoxy composites. The result of dispersion of SWCNTs in composites was observed by Scanning electron microscopy (SEM). Then the Glass Transition Temperature (Tg) of these kinds of composites with treated and untreated SWCNTs were obtained by Dynamic Mechanical Thermal Analysis (DMTA). Moreover, the bending properties of these composites were tested.

  4. Effects of the molecular level dispersion of graphene oxide on the free volume characteristics of poly(vinyl alcohol) and its impact on the thermal and mechanical properties of their nanocomposites.

    Science.gov (United States)

    Sharma, S K; Prakash, J; Pujari, P K

    2015-11-21

    Poly(vinyl alcohol), PVA, reinforced with carbon nanofillers has shown drastic variations in thermal as well as mechanical properties. In order to establish structure-property correlations, these variations have been correlated with modifications in the hydrogen bonding structure as well as the crystallinity of the PVA matrix without paying much attention to molecular packing in the amorphous region of this semicrystalline polymer. In order to investigate the molecular packing in PVA-graphene oxide (GO) nanocomposites, free volume characterization of PVA-GO nanocomposites has been carried out using ortho-positronium (o-Ps) probe. The variations in free volume size, density and size distribution have been determined through o-Ps lifetime and the corresponding intensity as well as its lifetime distribution. The variation in hydrogen bonding and its effect on crystallinity has been determined by Fourier Transform Infra Red (FTIR) and X-ray diffraction (XRD) measurements. The variation in the thermal (glass transition temperature) and mechanical (Young's modulus, tensile strength and percentage strain at break) properties of the nanocomposites is explained in view of the free volume structure and crystallinity of the PVA matrix which are severely modified due to the molecular-level dispersion of GO sheets in the PVA matrix.

  5. The ion exchange properties and equilibrium constants of Li+, Na+ and K+ on zirconium phosphate highly dispersed on a cellulose acetate fibers surface

    Directory of Open Access Journals (Sweden)

    Borgo Claudemir Adriano

    2004-01-01

    Full Text Available Highly dispersed zirconium phosphate was prepared by reacting celullose acetate/ZrO2 (ZrO2 = 11 wt%, 1.0 mmol g-1 of zirconium atom per gram of the material with phosphoric acid. High power decoupling magic angle spinning (HPDEC-MAS 31P NMR and X-ray photoelectron spectroscopy data indicated that HPO4(2- is the species present on the membrane surface. The specific concentration of acidic centers, determined by ammonia gas adsorption, is 0.60 mmol g-1. The ion exchange capacities for Li+, Na+ and K+ ions were determined from ion exchange isotherms at 298 K and showed the following values (in mmol g-1: Li+= 0.05, Na+= 0.38 and K+= 0.57. Due to the strong cooperative effect, the H+/Na+ and H+/K+ ion exchange is of non ideal nature. These ion exchange equilibria were treated with the use of models of fixed tridentate centers, which consider the surface of the sorbent as polyfunctional sorption centers. Both the observed ion exchange capacities with respect to the alkaline metal ions and the equilibrium constants are discussed by taking into consideration the sequence of the ionic hydration radii for Li+, Na+ and K+. The matrix affinity for the ions decreases with increasing the cations hydration radii from K+ to Li+. The high values of the separation factors S Na+/Li+ and S K+/Li+ (up to several hundreds support the application of this material for the quantitative separation of Na+ and K+ from Li+ from a mixture containing these three ions.

  6. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    International Nuclear Information System (INIS)

    Soltani, A.; Stolz, A.; Gerbedoen, J.-C.; Rousseau, M.; Bourzgui, N.; De Jaeger, J.-C.; Charrier, J.; Mattalah, M.; Barkad, H. A.; Mortet, V.; BenMoussa, A.

    2014-01-01

    Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450–1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films

  7. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, A., E-mail: ali.soltani@iemn.univ-lille1.fr; Stolz, A.; Gerbedoen, J.-C.; Rousseau, M.; Bourzgui, N.; De Jaeger, J.-C. [Institut d' Électronique, Microélectronique et Nanotechnologie, UMR-CNRS 8520, PRES Université Lille Nord de France, Cité Scientifique, Avenue Poincaré, CS 60069, 59652 Villeneuve d' Ascq Cedex (France); Charrier, J. [Fonctions Optiques pour les Technologies de l' informatiON, UMR-CNRS 6082, ENSSAT 6, rue de Kerampont, CS 80518, 22305 Lannion Cedex (France); Mattalah, M. [Laboratoire de Microélectronique, Université Djilali Liabes, 22000 Sidi Bel Abbes (Algeria); Barkad, H. A. [Institut Universitaire Technologique Industriel, Université de Djibouti, Avenue Georges Clémenceau, BP 1904 Djibouti (Djibouti); Mortet, V. [Institute of Physics of Academy of Sciences of Czech Republic, Fyzikální ústav AV CR, v.v.i., Na Slovance 1999/2 (Czech Republic); BenMoussa, A. [Solar Terrestrial Center of Excellence, Royal Observatory of Belgium, Circular 3, B-1180 Brussels (Belgium)

    2014-04-28

    Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450–1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films.

  8. Podem os dispersantes afetar as propriedades dos concretos refratários após a queima? Could the dispersants affect the properties of refractory castables after firing?

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2009-03-01

    Full Text Available A aplicação de concretos refratários é um processo em constante evolução e apresenta uma forte dependência dos avanços dos conhecimentos sobre os ligantes hidráulicos. Os cimentos de aluminato de cálcio constituem os agentes ligantes mais utilizados em concretos refratários, devido principalmente a sua disponibilidade, custo e capacidade de conferir alta resistência mecânica a verde. No entanto, a perda das ligações hidráulicas nestes materiais prejudica o seu desempenho a temperaturas intermediárias (500 a 1000 °C. Neste trabalho, as propriedades de concretos refratários foram avaliadas nesta faixa de temperatura, tendo como variável o tipo de dispersante utilizado uma vez que eles atuam no processo de hidratação de ligantes. Foi verificado que o efeito da atuação do dispersante é um dos fatores que determina o tipo de hidrato formado, que por sua vez influencia as propriedades de concretos. O aditivo que favoreceu a dispersão do concreto e menor consumo de água levou a formação de hidratos termicamente mais estáveis. Isso contribuiu para aumentar a resistência mecânica em temperaturas intermediárias e influenciou o comportamento termomecânico do concreto em alta temperatura.A growing demand for refractory castables with specific behavior has been inducing a continuous technological evolution, where one of the most important aspects is related to the hydraulic binders. The high alumina cements are the most important hydraulically setting agents used for bonding castables, mainly because they develop high strength within 6-24 h of placement. However, conventional castables show a characteristic drop in the mechanical strength in the 500 to 1000 °C temperature range, when the hydraulic bond is lost due to the dehydration process. In this work, the influence of dispersants in the refractory castables properties was evaluated as a function of firing temperature. It was verified that the hydrate type formed during

  9. The liberal illusion of uniqueness.

    Science.gov (United States)

    Stern, Chadly; West, Tessa V; Schmitt, Peter G

    2014-01-01

    In two studies, we demonstrated that liberals underestimate their similarity to other liberals (i.e., display truly false uniqueness), whereas moderates and conservatives overestimate their similarity to other moderates and conservatives (i.e., display truly false consensus; Studies 1 and 2). We further demonstrated that a fundamental difference between liberals and conservatives in the motivation to feel unique explains this ideological distinction in the accuracy of estimating similarity (Study 2). Implications of the accuracy of consensus estimates for mobilizing liberal and conservative political movements are discussed.

  10. Cefuroxime axetil solid dispersions prepared using solution enhanced dispersion by supercritical fluids.

    Science.gov (United States)

    Jun, Seoung Wook; Kim, Min-Soo; Jo, Guk Hyun; Lee, Sibeum; Woo, Jong Soo; Park, Jeong-Sook; Hwang, Sung-Joo

    2005-12-01

    Cefuroxime axetil (CA) solid dispersions with HPMC 2910/PVP K-30 were prepared using solution enhanced dispersion by supercritical fluids (SEDS) in an effort to increase the dissolution rate of poorly water-soluble drugs. Their physicochemical properties in solid state were characterized by differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy. No endothermic and characteristic diffraction peaks corresponding to CA were observed for the solid dispersions in DSC and PXRD. FTIR analysis demonstrated the presence of intermolecular hydrogen bonds between CA and HPMC 2910/PVP K-30 in solid dispersions, resulting in the formation of amorphous or non-crystalline CA. Dissolution studies indicated that the dissolution rates were remarkably increased in solid dispersions compared with those in the physical mixture and drug alone. In conclusion, an amorphous or non-crystalline CA solid dispersion prepared using SEDS could be very useful for the formulation of solid dosage forms.

  11. Dispersed Fringe Sensing Analysis - DFSA

    Science.gov (United States)

    Sigrist, Norbert; Shi, Fang; Redding, David C.; Basinger, Scott A.; Ohara, Catherine M.; Seo, Byoung-Joon; Bikkannavar, Siddarayappa A.; Spechler, Joshua A.

    2012-01-01

    Dispersed Fringe Sensing (DFS) is a technique for measuring and phasing segmented telescope mirrors using a dispersed broadband light image. DFS is capable of breaking the monochromatic light ambiguity, measuring absolute piston errors between segments of large segmented primary mirrors to tens of nanometers accuracy over a range of 100 micrometers or more. The DFSA software tool analyzes DFS images to extract DFS encoded segment piston errors, which can be used to measure piston distances between primary mirror segments of ground and space telescopes. This information is necessary to control mirror segments to establish a smooth, continuous primary figure needed to achieve high optical quality. The DFSA tool is versatile, allowing precise piston measurements from a variety of different optical configurations. DFSA technology may be used for measuring wavefront pistons from sub-apertures defined by adjacent segments (such as Keck Telescope), or from separated sub-apertures used for testing large optical systems (such as sub-aperture wavefront testing for large primary mirrors using auto-collimating flats). An experimental demonstration of the coarse-phasing technology with verification of DFSA was performed at the Keck Telescope. DFSA includes image processing, wavelength and source spectral calibration, fringe extraction line determination, dispersed fringe analysis, and wavefront piston sign determination. The code is robust against internal optical system aberrations and against spectral variations of the source. In addition to the DFSA tool, the software package contains a simple but sophisticated MATLAB model to generate dispersed fringe images of optical system configurations in order to quickly estimate the coarse phasing performance given the optical and operational design requirements. Combining MATLAB (a high-level language and interactive environment developed by MathWorks), MACOS (JPL s software package for Modeling and Analysis for Controlled Optical

  12. Coexistence of uniquely ergodic subsystems of interval mapping

    International Nuclear Information System (INIS)

    Ye Xiangdong.

    1991-10-01

    The purpose of this paper is to show that uniquely ergodic subsystems of interval mapping also coexist in the same way as minimal sets do. To do this we give some notations in section 2. In section 3 we define D-function of a uniquely ergodic system and show its basic properties. We prove the coexistence of uniquely ergodic subsystems of interval mapping in section 4. Lastly we give the examples of uniquely ergodic systems with given D-functions in section 5. 27 refs

  13. Effect of HIP temperatures on the microstructure and mechanical properties of carbide dispersed Ti-48Al-1Mn mechanically alloyed compacts

    International Nuclear Information System (INIS)

    Ameyama, Kei; Hashii, Mitsuya; Imai, Nobuyuki; Fujii, Toshinori; Sasaki, Nobuyuki.

    1996-01-01

    The effect of hot isostatic pressing (HIP) temperature on the microstructure and mechanical properties of Ti-48 mol%Al-1 mol%Mn compacts fabricated by mechanical alloying was investigated. N-heptane was used as a process control agent for the mechanical alloying. The compacts HIP treated at 1173, 1373 or 1573 K showed an ultra-fine equiaxed grain structure, i.e., a microduplex structure, consisting of TiAl (γ) and Ti 2 AlC phases, and their average grain sizes were 185 nm, 510 nm and 1.5 μm, respectively. The γ phase was considered to be formed by an α → γ massive transformation during heating. On the other hand, the compacts HIP treated at 1623 or 1673 K showed quite different microstructures from the above HIP compacts. The 1623 K-HIP compact was composed of equiaxed γ grains, whose size was approximately 11.5 μm, rectangular shaped Ti 2 AlC particles, and a small amount of the grain boundary nucleated α phase. Although the 1673 K-HIP compact showed a microstructure similar to the 1623 K-HIP compact, the γ grains were coarsened to be approximately 27.8 μm in diameter and the Ti 2 AlC particles were more elongated rectangles. Furthermore, the amount of the grain boundary nucleated α phase was increased and the lamella α phase nucleated at γ twin boundaries was observed in the 1673 K-HIP compact. Mechanical properties determined by compressive testing at various temperatures made clear that the compacts HIP treated at 1173, 1373 or 1573 K have good workability at elevated temperatures and those HIP treated at 1623 or 1673 K have good high temperature strength. These mechanical properties were influenced significantly by the microstructure, especially by the grain size and morphology of the Ti 2 AlC phase. (author)

  14. Non-unique Product Groups on Two Generators

    OpenAIRE

    Carter, William Paul

    2007-01-01

    The main purpose of this paper is to better understand groups that do not have the unique product property. In particular, the goal is to better understand Promislow's example, G, of such a group. In doing so, we will develop methods for generating examples of other sets that do not have the unique product property. With these methods we can show that there exists other distinct 14 element, square, non-unique product sets in G that are not inversions or translations. Also, this paper answers ...

  15. The general dispersion relation of induced streaming instabilities in quantum outflow systems

    Energy Technology Data Exchange (ETDEWEB)

    Mehdian, H., E-mail: mehdian@khu.ac.ir; Hajisharifi, K.; Hasanbeigi, A. [Department of Physics and Institute for Plasma Research, Kharazmi University, 49 Dr Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)

    2015-11-15

    In this manuscript the dispersion relations of streaming instabilities, by using the unique property (neutralized in charge and current by default) of plasma shells colliding, have been generalized and studied. This interesting property for interpenetrating beams enables one to find the general dispersion relations without any restrictions used in the previous works in this area. In our previous work [H. Mehdian et al., ApJ. 801, 89 (2015)], employing the plasma shell concept and boost frame method, the general dispersion relation for filamentation instability has been derived in the relativistic classical regime. But in this paper, using the above mentioned concepts, the general dispersion relations (for each of streaming instabilities, filamentation, two-stream and multi-stream) in the non-relativistic quantum regime have been derived by employing the quantum fluid equations together with Maxwell equations. The derived dispersion relations enable to describe any arbitrary system of interacting two and three beams, justified neutralization condition, by choosing the inertial reference frame embedded on the one of the beams. Furthermore, by the numerical and analytical study of these dispersion relations, many new features of streaming instabilities (E.g. their cut-off wave numbers and growth rates) in terms of all involved parameters have been illustrated. The obtained results in this paper can be used to describe many astrophysical systems and laboratory astrophysics setting, such as collision of non-parallel plasma shells over a background plasma or the collision of three neutralized plasma slabs, and justifying the many plasma phenomena such as particle accelerations and induced fields.

  16. Oxide dispersion strengthened ferritic alloys. 14/20% chromium: effects of processing on deformation texture, recrystallization and tensile properties; Alliages ferritiques 14/20% de chrome renforces par dispersion d`oxydes. Effets des procedes de mise en forme sur les textures de deformation, la recristallisation et les proprietes de traction

    Energy Technology Data Exchange (ETDEWEB)

    Regle, H

    1994-12-31

    The ferritic oxide dispersion strengthened alloys are promising candidates for high temperature application materials, in particular for long life core components of advanced nuclear reactors. The aim of this work is to control the microstructure, in order to optimise the mechanical properties. The two ferritic alloys examined here, MA956 and MA957, are obtained by Mechanical Alloying techniques. They are characterised by quite anisotropic microstructure and mechanical properties. We have investigated the influence of hot and cold working processes (hot extrusion, swaging and cold-drawing) and recrystallization heat treatments on deformation textures, microstructures and tensile properties. The aim was to control the size of the grains and their anisotropic shape, using recrystallization heat treatments. After consolidation and hot extrusion, as-received materials present a extremely fine microstructure with elongated grains and a very strong (110) deformation texture with single-crystal character. At that stage of processing, recrystallization temperature are very high (1450 degrees C for MA957 alloy and 1350 degrees C for MA956 alloy) and materials develop millimetric recrystallized grains. Additional hot extrusion induce a fibre texture. Cold-drawing maintains a fibre texture, but the intensity decreases with increasing cold-work level. For both materials, the decrease of texture intensities correspond to a decrease of the recrystallization temperatures (from 1350 degrees C for a low cold-work level to 750 degrees C for 60 % cold-deformation, case of MA956 alloy) and a refinement of the grain size (from a millimetric size to less than an hundred of micrometer). Swaging develop a cyclic component where the intensity increases with increasing deformation in this case, the recrystallization temperature remains always very high and the millimetric grain size is slightly modified, even though cold-work level increases. (Abstract Truncated)

  17. Microstructure and tensile properties of oxide dispersion strengthened Fe–14Cr–0.3Y2O3 and Fe–14Cr–2W–0.3Ti–0.3Y2O3

    International Nuclear Information System (INIS)

    Auger, M.A.; Castro, V. de; Leguey, T.; Monge, M.A.; Muñoz, A.; Pareja, R.

    2013-01-01

    Two ODS ferritic steels with nominal compositions (wt.%): Fe–14Cr–0.3Y 2 O 3 and Fe–14Cr–2W–0.3Ti–0.3Y 2 O 3 have been produced by mechanical alloying and consolidation by hot isostatic pressing. The microstructure and tensile properties of these materials after being forged and heat-treated at 1123 K have been investigated to clarify the interrelation between composition, microstructure and mechanical properties. The second-phase precipitates in these alloys have been analyzed by high-angle annular dark-field imaging in scanning TEM mode and electron diffraction. Fe–14Cr–2W–0.3Ti–0.3Y 2 O 3 exhibits a duplex microstructure consisting of large recrystallized grains, as large as 1.5 μm, and unrecovered regions containing submicron equiaxed grains. In addition, three types of secondary phase particles have been found: large M 23 C 6 particles containing W and Cr, (Cr + Ti) rich spherical particles with diameters between 50 and 500 nm, and fine (Y + Ti) oxide particles with sizes below 30 nm. In contrast, Fe14CrY shows a uniform structure of equiaxed grains, with sizes in the range 0.5–3 μm, containing a fine dispersion of Y oxide particles ( 2 O 3 at temperatures up to 773 K, but the opposite appears to occur beyond this temperature

  18. Dispersal of forest insects

    Science.gov (United States)

    Mcmanus, M. L.

    1979-01-01

    Dispersal flights of selected species of forest insects which are associated with periodic outbreaks of pests that occur over large contiguous forested areas are discussed. Gypsy moths, spruce budworms, and forest tent caterpillars were studied for their massive migrations in forested areas. Results indicate that large dispersals into forested areas are due to the females, except in the case of the gypsy moth.

  19. Improved new generation dispersants

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    The use of dispersants to combat oil spills has attracted controversy over the years, and there has been a number of accusations of the chemicals involved doing more harm than good. A new study by the International Petroleum Industry Environmental Conservation Association discusses the positive and the negatives of dispersant use to be considered when drawing up spill contingency plans. (author)

  20. Seed dispersal in fens

    Science.gov (United States)

    Middleton, B.; Van Diggelen, R.; Jensen, K.

    2006-01-01

    Question: How does seed dispersal reduce fen isolation and contribute to biodiversity? Location: European and North American fens. Methods: This paper reviews the literature on seed dispersal to fens. Results: Landscape fragmentation may reduce dispersal opportunities thereby isolating fens and reducing genetic exchange. Species in fragmented wetlands may have lower reproductive success, which can lead to biodiversity loss. While fens may have always been relatively isolated from each other, they have become increasingly fragmented in modern times within agricultural and urban landscapes in both Europe and North America. Dispersal by water, animals and wind has been hampered by changes related to development in landscapes surrounding fens. Because the seeds of certain species are long-lived in the seed bank, frequent episodes of dispersal are not always necessary to maintain the biodiversity of fens. However, of particular concern to restoration is that some dominant species, such as the tussock sedge Carex stricta, may not disperse readily between fens. Conclusions: Knowledge of seed dispersal can be used to maintain and restore the biodiversity of fens in fragmented landscapes. Given that development has fragmented landscapes and that this situation is not likely to change, the dispersal of seeds might be enhanced by moving hay or cattle from fens to damaged sites, or by reestablishing lost hydrological connections. ?? IAVS; Opulus Press.

  1. Kosovo case: A unique arbitrariness

    Directory of Open Access Journals (Sweden)

    Nakarada Radmila

    2007-01-01

    Full Text Available The end of Cold war, contrary to expectations has brought new conflicts and forms of violence, new divisions and new relativizations of the international legal order. Taking as an example the endeavors to resolve the Kosovo conflict, the author attempts to indicate the broader implications of the international efforts to constitute an independent state on part of the territory of an existing sovereign state. The arguments used to justify the redefinition of the borders of the Serbian state without its consent, the moral, democratic, peace arguments, are reviewed. Particular attention is paid to the argument that Kosovo is a unique case and therefore unique rules should be applied. The author seeks to understand the deeper significance of these efforts, concluding that dismantling the present international legal order is not only a potential danger but a possible aim.

  2. Uniqueness theorems in linear elasticity

    CERN Document Server

    Knops, Robin John

    1971-01-01

    The classical result for uniqueness in elasticity theory is due to Kirchhoff. It states that the standard mixed boundary value problem for a homogeneous isotropic linear elastic material in equilibrium and occupying a bounded three-dimensional region of space possesses at most one solution in the classical sense, provided the Lame and shear moduli, A and J1 respectively, obey the inequalities (3 A + 2 J1) > 0 and J1>O. In linear elastodynamics the analogous result, due to Neumann, is that the initial-mixed boundary value problem possesses at most one solution provided the elastic moduli satisfy the same set of inequalities as in Kirchhoffs theorem. Most standard textbooks on the linear theory of elasticity mention only these two classical criteria for uniqueness and neglect altogether the abundant literature which has appeared since the original publications of Kirchhoff. To remedy this deficiency it seems appropriate to attempt a coherent description ofthe various contributions made to the study of uniquenes...

  3. First-principles study of paraelectric and ferroelectric CsH2PO4 including dispersion forces: Stability and related vibrational, dielectric, and elastic properties

    Science.gov (United States)

    Van Troeye, Benoit; van Setten, Michiel Jan; Giantomassi, Matteo; Torrent, Marc; Rignanese, Gian-Marco; Gonze, Xavier

    2017-01-01

    Using density functional theory (DFT) and density functional perturbation theory (DFPT), we investigate the stability and response functions of CsH2PO4 , a ferroelectric material at low temperature. This material cannot be described properly by the usual (semi)local approximations within DFT. The long-range e--e- correlation needs to be properly taken into account, using, for instance, Grimme's DFT-D methods, as investigated in this work. We find that DFT-D3(BJ) performs the best for the members of the dihydrogenated alkali phosphate family (KH2PO4 , RbH2PO4 , CsH2PO4 ), leading to experimental lattice parameters reproduced with an average deviation of 0.5%. With these DFT-D methods, the structural, dielectric, vibrational, and mechanical properties of CsH2PO4 are globally in excellent agreement with the available experiments (<2 % MAPE for Raman-active phonons). Our study suggests the possible existence of a new low-temperature phase of CsH2PO4 , not yet reported experimentally. Finally, we report the implementation of DFT-D contributions to elastic constants within DFPT.

  4. Taylor dispersion on a fractal

    International Nuclear Information System (INIS)

    Mazo, R.M.

    1998-01-01

    Taylor dispersion is the greatly enhanced diffusion in the direction of a fluid flow caused by ordinary diffusion in directions orthogonal to the flow. It is essential that the system be bounded in space in the directions orthogonal to the flow. We investigate the situation where the medium through which the flow occurs has fractal properties so that diffusion in the orthogonal directions is anomalous and non-Fickian. The effective diffusion in the flow direction remains normal; its width grows proportionally with the time. However, the proportionality constant depends on the fractal dimension of the medium as well as its walk dimension. (author)

  5. Dispersal and metapopulation stability

    Directory of Open Access Journals (Sweden)

    Shaopeng Wang

    2015-10-01

    Full Text Available Metapopulation dynamics are jointly regulated by local and spatial factors. These factors may affect the dynamics of local populations and of the entire metapopulation differently. Previous studies have shown that dispersal can stabilize local populations; however, as dispersal also tends to increase spatial synchrony, its net effect on metapopulation stability has been controversial. Here we present a simple metapopulation model to study how dispersal, in interaction with other spatial and local processes, affects the temporal variability of metapopulations in a stochastic environment. Our results show that in homogeneous metapopulations, the local stabilizing and spatial synchronizing effects of dispersal cancel each other out, such that dispersal has no effect on metapopulation variability. This result is robust to moderate heterogeneities in local and spatial parameters. When local and spatial dynamics exhibit high heterogeneities, however, dispersal can either stabilize or destabilize metapopulation dynamics through various mechanisms. Our findings have important theoretical and practical implications. We show that dispersal functions as a form of spatial intraspecific mutualism in metapopulation dynamics and that its effect on metapopulation stability is opposite to that of interspecific competition on local community stability. Our results also suggest that conservation corridors should be designed with appreciation of spatial heterogeneities in population dynamics in order to maximize metapopulation stability.

  6. Superior Performance Nanocomposites from Uniformly Dispersed Octadecylamine Functionalized Multi-Walled Carbon Nanotubes

    KAUST Repository

    Chen, Ye

    2015-12-08

    Polyetherimide (PEI) is a widely applied as engineering plastic in the electronics, aerospace, and automotive industries but the disadvantages of extremely low conductivity, atmospheric moisture absorption, and poor fluidity at high temperature limits its application. Herein, commercial multi-walled carbon nanotubes (MWCNTs) were modified with a long alkyl chain molecule, octadecylamine (ODA), to produce a uniform dispersion in commercial PEI matrices. Both covalent and noncovalent modification of MWCNTs with ODA, were prepared and compared. Modified MWCNTs were incorporated in PEI matrices to fabricate nanocomposite membranes by a simple casting method. Investigating mechanical properties, thermal stability, and conductivity of the polyetherimide (PEI)/MWCNT composites showed a unique combination of properties, such as high electrical conductivity, high mechanical properties, and high thermal stability at a low content of 1.0 wt % loading of ODA modified MWCNTs. Moreover, electrical resistivity decreased around 10 orders of magnitude with only 0.5 wt % of modified MWCNTs.

  7. Superior Performance Nanocomposites from Uniformly Dispersed Octadecylamine Functionalized Multi-Walled Carbon Nanotubes

    KAUST Repository

    Chen, Ye; Tao, Jing; Ezzeddine, Alaa; Mahfouz, Remi; Al-Shahrani, Abdullah; Alabedi, Gasan; Khashab, Niveen M.

    2015-01-01

    Polyetherimide (PEI) is a widely applied as engineering plastic in the electronics, aerospace, and automotive industries but the disadvantages of extremely low conductivity, atmospheric moisture absorption, and poor fluidity at high temperature limits its application. Herein, commercial multi-walled carbon nanotubes (MWCNTs) were modified with a long alkyl chain molecule, octadecylamine (ODA), to produce a uniform dispersion in commercial PEI matrices. Both covalent and noncovalent modification of MWCNTs with ODA, were prepared and compared. Modified MWCNTs were incorporated in PEI matrices to fabricate nanocomposite membranes by a simple casting method. Investigating mechanical properties, thermal stability, and conductivity of the polyetherimide (PEI)/MWCNT composites showed a unique combination of properties, such as high electrical conductivity, high mechanical properties, and high thermal stability at a low content of 1.0 wt % loading of ODA modified MWCNTs. Moreover, electrical resistivity decreased around 10 orders of magnitude with only 0.5 wt % of modified MWCNTs.

  8. Diversity in the stellar velocity dispersion profiles of a large sample of brightest cluster galaxies z ≤ 0.3

    Science.gov (United States)

    Loubser, S. I.; Hoekstra, H.; Babul, A.; O'Sullivan, E.

    2018-06-01

    We analyse spatially resolved deep optical spectroscopy of brightestcluster galaxies (BCGs) located in 32 massive clusters with redshifts of 0.05 ≤ z ≤ 0.30 to investigate their velocity dispersion profiles. We compare these measurements to those of other massive early-type galaxies, as well as central group galaxies, where relevant. This unique, large sample extends to the most extreme of massive galaxies, spanning MK between -25.7 and -27.8 mag, and host cluster halo mass M500 up to 1.7 × 1015 M⊙. To compare the kinematic properties between brightest group and cluster members, we analyse similar spatially resolved long-slit spectroscopy for 23 nearby brightest group galaxies (BGGs) from the Complete Local-Volume Groups Sample. We find a surprisingly large variety in velocity dispersion slopes for BCGs, with a significantly larger fraction of positive slopes, unique compared to other (non-central) early-type galaxies as well as the majority of the brightest members of the groups. We find that the velocity dispersion slopes of the BCGs and BGGs correlate with the luminosity of the galaxies, and we quantify this correlation. It is not clear whether the full diversity in velocity dispersion slopes that we see is reproduced in simulations.

  9. Simple Technique of Exfoliation and Dispersion of Multilayer Graphene from Natural Graphite by Ozone-Assisted Sonication.

    Science.gov (United States)

    Lin, Zaw; Karthik, Paneer Selvam; Hada, Masaki; Nishikawa, Takeshi; Hayashi, Yasuhiko

    2017-05-27

    Owing to its unique properties, graphene has attracted tremendous attention in many research fields. There is a great space to develop graphene synthesis techniques by an efficient and environmentally friendly approach. In this paper, we report a facile method to synthesize well-dispersed multilayer graphene (MLG) without using any chemical reagents or organic solvents. This was achieved by the ozone-assisted sonication of the natural graphite in a water medium. The frequency or number of ozone treatments plays an important role for the dispersion in the process. The possible mechanism of graphene exfoliation and the introduction of functional groups have been postulated. The experimental setup is unique for ozone treatment and enables the elimination of ozone off-gas. The heat generated by the dissipation of ultrasonic waves was used as it is, and no additional heat was supplied. The graphene dispersion was stable, and no evidence of aggregation was observed---even after several months. The characterization results show that well-dispersed MLG was successfully synthesized without any significant damage to the overall structure. The graphene obtained by this method has potential applications in composite materials, conductive coatings, energy storage, and electronic devices.

  10. Simple Technique of Exfoliation and Dispersion of Multilayer Graphene from Natural Graphite by Ozone-Assisted Sonication

    Directory of Open Access Journals (Sweden)

    Zaw Lin

    2017-05-01

    Full Text Available Owing to its unique properties, graphene has attracted tremendous attention in many research fields. There is a great space to develop graphene synthesis techniques by an efficient and environmentally friendly approach. In this paper, we report a facile method to synthesize well-dispersed multilayer graphene (MLG without using any chemical reagents or organic solvents. This was achieved by the ozone-assisted sonication of the natural graphite in a water medium. The frequency or number of ozone treatments plays an important role for the dispersion in the process. The possible mechanism of graphene exfoliation and the introduction of functional groups have been postulated. The experimental setup is unique for ozone treatment and enables the elimination of ozone off-gas. The heat generated by the dissipation of ultrasonic waves was used as it is, and no additional heat was supplied. The graphene dispersion was stable, and no evidence of aggregation was observed---even after several months. The characterization results show that well-dispersed MLG was successfully synthesized without any significant damage to the overall structure. The graphene obtained by this method has potential applications in composite materials, conductive coatings, energy storage, and electronic devices.

  11. The Uniqueness of Milton Friedman

    OpenAIRE

    J. Daniel Hammond

    2013-01-01

    That there is no Milton Friedman today is not a mystery; the mystery is how Milton Friedman could have been. The facts of Friedman’s biography make him unique among twentieth-century public figures. He had extensive knowledge and expertise in mathematics and statistics. Yet he became a critic of ‘formal’ theory, exemplified by mathematical economics, that failed to engage with real-world facts and data, and of econometric modeling that presumed more knowledge of economic structure than Friedm...

  12. Unique Features of Halophilic Proteins.

    Science.gov (United States)

    Arakawa, Tsutomu; Yamaguchi, Rui; Tokunaga, Hiroko; Tokunaga, Masao

    2017-01-01

    Proteins from moderate and extreme halophiles have unique characteristics. They are highly acidic and hydrophilic, similar to intrinsically disordered proteins. These characteristics make the halophilic proteins soluble in water and fold reversibly. In addition to reversible folding, the rate of refolding of halophilic proteins from denatured structure is generally slow, often taking several days, for example, for extremely halophilic proteins. This slow folding rate makes the halophilic proteins a novel model system for folding mechanism analysis. High solubility and reversible folding also make the halophilic proteins excellent fusion partners for soluble expression of recombinant proteins.

  13. A unique gesture of sharing

    International Nuclear Information System (INIS)

    Mustafa, T.

    1985-01-01

    The Atoms for Peace program was a unique gesture of sharing on the part of the leading industrialized nation, and has very few parallels in modern history. The author says one of the major advantages of the program for developing nations was the much needed stimulation of their indigenous science and technology efforts and the awakening of their governments to the multifaceted benefits of atomic energy. The author discusses how the program benefited Pakistan in the production of electrical energy and in the application of nuclear techniques in the fields of agriculture and medicine, which help to alleviate hunger and combat disease

  14. New Examples of Torsion-Free Non-unique Product Groups

    OpenAIRE

    Carter, William

    2013-01-01

    We give an infinite family of torsion-free groups that do not satisfy the unique product property. For these examples, we also show that each group contains arbitrarily large sets whose square has no uniquely represented element.

  15. Modeling electrical dispersion phenomena in Earth materials

    Directory of Open Access Journals (Sweden)

    D. Patella

    2008-06-01

    Full Text Available It is illustrated that IP phenomena in rocks can be described using conductivity dispersion models deduced as solutions to a 2nd-order linear differential equation describing the motion of a charged particle immersed in an external electrical field. Five dispersion laws are discussed, namely: the non-resonant positive IP model, which leads to the classical Debye-type dispersion law and by extension to the Cole-Cole model, largely used in current practice; the non-resonant negative IP model, which allows negative chargeability values, known in metals at high frequencies, to be explained as an intrinsic physical property of earth materials in specific field cases; the resonant flat, positive or negative IP models, which can explain the presence of peak effects at specific frequencies superimposed on flat, positive or negative dispersion spectra.

  16. Functionalization and Dispersion of Carbon Nanomaterials Using an Environmentally Friendly Ultrasonicated Ozonolysis Process.

    Science.gov (United States)

    Yeo, Eudora S Y; Mathys, Gary I; Brack, Narelle; Thostenson, Erik T; Rider, Andrew N

    2017-05-30

    Functionalization of carbon nanomaterials is often a critical step that facilitates their integration into larger material systems and devices. In the as-received form, carbon nanomaterials, such as carbon nanotubes (CNTs) or graphene nanoplatelets (GNPs), may contain large agglomerates. Both agglomerates and impurities will diminish the benefits of the unique electrical and mechanical properties offered when CNTs or GNPs are incorporated into polymers or composite material systems. Whilst a variety of methods exist to functionalize carbon nanomaterials and to create stable dispersions, many the processes use harsh chemicals, organic solvents, or surfactants, which are environmentally unfriendly and may increase the processing burden when isolating the nanomaterials for subsequent use. The current research details the use of an alternative, environmentally friendly technique for functionalizing CNTs and GNPs. It produces stable, aqueous dispersions free of harmful chemicals. Both CNTs and GNPs can be added to water at concentrations up to 5 g/L and can be recirculated through a high-powered ultrasonic cell. The simultaneous injection of ozone into the cell progressively oxidizes the carbon nanomaterials, and the combined ultrasonication breaks down agglomerates and immediately exposes fresh material for functionalization. The prepared dispersions are ideally suited for the deposition of thin films onto solid substrates using electrophoretic deposition (EPD). CNTs and GNPs from the aqueous dispersions can be readily used to coat carbon- and glass-reinforcing fibers using EPD for the preparation of hierarchical composite materials.

  17. A costal dispersion model

    International Nuclear Information System (INIS)

    Rahm, L.; Nyberg, L.; Gidhagen, L.

    1990-01-01

    A dispersion model to be used off costal waters has been developed. The model has been applied to describe the migration of radionuclides in the Baltic sea. A summary of the results is presented here. (K.A.E)

  18. Wave-equation dispersion inversion

    KAUST Repository

    Li, Jing; Feng, Zongcai; Schuster, Gerard T.

    2016-01-01

    We present the theory for wave-equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. The dispersion curves are obtained

  19. Reactimeter dispersion equation

    OpenAIRE

    A.G. Yuferov

    2016-01-01

    The aim of this work is to derive and analyze a reactimeter metrological model in the form of the dispersion equation which connects reactimeter input/output signal dispersions with superimposed random noise at the inlet. It is proposed to standardize the reactimeter equation form, presenting the main reactimeter computing unit by a convolution equation. Hence, the reactimeter metrological characteristics are completely determined by this unit hardware function which represents a transient re...

  20. Transverse dispersion in heterogeneous fractures

    International Nuclear Information System (INIS)

    Dershowitz, Bill; Shuttle, Dawn; Klise, Kate; Outters, Nils; Hermanson, Jan

    2004-12-01

    This report evaluates the significance of transverse dispersion processes for solute transport in a single fracture. Transverse dispersion is a potentially significant process because it increases the fracture surface area available for sorptive and diffusive properties, and has the potential to transport solute between what would otherwise be distinctive, streamline pathways. Transverse dispersion processes are generally ignored in one-dimensional repository performance assessment approaches. This report provides an initial assessment of the magnitude of transverse dispersion effect in a single heterogeneous fracture on repository safety assessment. This study builds on a previous report which considered the network effects on transport dispersion including streamline routing and mixing at fracture intersections. The project uses FracMan software. This platform has been extensively used by SKB in other projects. FracMan software is designed to generate and analyze DFN's as well as to compute fluid flow in DFN's with the MAFIC Finite element method (FEM) code. Solute transport was modeled using the particle tracking inside MAFIC, the 2-D Laplace Transform Galerkin inside PAWorks/LTG, and the 1-D Laplace Transform approach designed to replicate FARF31 inside GoldSim.The study reported here focuses on a single, 20-meter scale discrete fracture, with simplified boundary conditions intended to represent the position of this fracture within a fracture network. The range of assumptions made regarding fracture heterogeneity were as follows: Base case, Heterogeneous fracture, geostatistical field, correlation length 0.01 m. Case 1a, Homogeneous fracture, transmissivity = 10 -7 m 2 /s. Case 1b, Heterogeneous fracture, non-channeled geostatistical field correlation length 5 m. Case 1c, Heterogeneous fracture, channeled, anisotropic geostatistical field. Case 1d, Heterogeneous fracture, fracture intersection zone (FIZ) permeability enhanced. Case 5, Simple channelized

  1. Fickian dispersion is anomalous

    Science.gov (United States)

    Cushman, John H.; O'Malley, Dan

    2015-12-01

    The thesis put forward here is that the occurrence of Fickian dispersion in geophysical settings is a rare event and consequently should be labeled as anomalous. What people classically call anomalous is really the norm. In a Lagrangian setting, a process with mean square displacement which is proportional to time is generally labeled as Fickian dispersion. With a number of counter examples we show why this definition is fraught with difficulty. In a related discussion, we show an infinite second moment does not necessarily imply the process is super dispersive. By employing a rigorous mathematical definition of Fickian dispersion we illustrate why it is so hard to find a Fickian process. We go on to employ a number of renormalization group approaches to classify non-Fickian dispersive behavior. Scaling laws for the probability density function for a dispersive process, the distribution for the first passage times, the mean first passage time, and the finite-size Lyapunov exponent are presented for fixed points of both deterministic and stochastic renormalization group operators. The fixed points of the renormalization group operators are p-self-similar processes. A generalized renormalization group operator is introduced whose fixed points form a set of generalized self-similar processes. Power-law clocks are introduced to examine multi-scaling behavior. Several examples of these ideas are presented and discussed.

  2. Quasi-homogenous approximation for description of the properties of dispersed systems. The basic approaches to model hardening processes in nanodispersed silica systems. Part 3. Penetration of energy barriers

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2015-06-01

    Full Text Available The paper deals with possibilities to use quasi-homogenous approximation for discription of properties of dispersed systems. The authors applied statistical polymer method based on consideration of average structures of all possible macromolecules of the same weight. The equiations which allow evaluating many additive parameters of macromolecules and the systems with them were deduced. Statistical polymer method makes it possible to model branched, cross-linked macromolecules and the systems with them which are in equilibrium or non-equilibrium state. Fractal analysis of statistical polymer allows modeling different types of random fractal and other objects examined with the mehods of fractal theory. The method of fractal polymer can be also applied not only to polymers but also to composites, gels, associates in polar liquids and other packaged systems. There is also a description of the states of colloid solutions of silica oxide from the point of view of statistical physics. This approach is based on the idea that colloid solution of silica dioxide – sol of silica dioxide – consists of enormous number of interacting particles which are always in move. The paper is devoted to the research of ideal system of colliding but not interacting particles of sol. The analysis of behavior of silica sol was performed according to distribution Maxwell-Boltzmann and free path length was calculated. Using this data the number of the particles which can overcome the potential barrier in collision was calculated. To model kinetics of sol-gel transition different approaches were studied.

  3. Quasi-homogenous approximation for description of the properties of dispersed systems. The basic approaches to model hardening processes in nanodispersed silica systems. Part 4. The Main Approaches to Modeling the Kinetics of the Sol-Gel Transition

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2015-08-01

    Full Text Available The paper deals with possibilities to use quasi-homogenous approximation for description of properties of dispersed systems. The authors applied statistical polymer method based on consideration of average structures of all possible macromolecules of the same weight. The equations which allow evaluating many additive parameters of macromolecules and the systems with them were deduced. Statistical polymer method makes it possible to model branched, cross-linked macromolecules and the systems with them which are in equilibrium or non-equilibrium state. Fractal analysis of statistical polymer allows modeling different types of random fractal and other objects examined with the methods of fractal theory. The method of fractal polymer can be applied not only to polymers but also to composites, gels, associates in polar liquids and other packaged systems. There is also a description of the states of colloid solutions of silica oxide from the point of view of statistical physics. This approach is based on the idea that colloid solution of silica dioxide – sol of silica dioxide – consists of enormous number of interacting particles which are always in move. The paper is devoted to the research of ideal system of colliding but not interacting particles of sol. The analysis of behavior of silica sol was performed according to distribution Maxwell-Boltzmann and free path length was calculated. Using this data the number of the particles which can overcome the potential barrier in collision was calculated. To model kinetics of sol-gel transition different approaches were studied.

  4. Quasi-homogenous approximation for description of the properties of dispersed systems. The basic approaches to model hardening processes in nanodispersed silica systems. Part 2. The hardening processes from the standpoint of statistical physics

    Directory of Open Access Journals (Sweden)

    KUDRYAVTSEV Pavel Gennadievich

    2015-04-01

    Full Text Available The paper deals with possibilities to use quasi-homogenous approximation for discription of properties of dispersed systems. The authors applied statistical polymer ethod based on consideration of average structures of all possible macromolecules of the same weight. The equiations which allow evaluating many additive parameters of macromolecules and the systems with them were deduced. Statistical polymer method makes it possible to model branched, cross-linked macromolecules and the systems with them which are in equilibrium or non-equilibrium state. Fractal analysis of statistical polymer allows modeling different types of random fractal and other objects examined with the mehods of fractal theory. The method of fractal polymer can be also applied not only to polymers but also to composites, gels, associates in polar liquids and other packaged systems. There is also a description of the states of colloid solutions of silica oxide from the point of view of statistical physics. This approach is based on the idea that colloid solution of silica dioxide – sol of silica dioxide – consists of enormous number of interacting particles which are always in move. The paper is devoted to the research of ideal system of colliding but not interacting particles of sol. The analysis of behavior of silica sol was performed according to distribution Maxwell-Boltzmann and free path length was calculated. Using this data the number of the particles which can overcome the potential barrier in collision was calculated. To model kinetics of sol-gel transition different approaches were studied.

  5. Unique Features of Mobile Commerce

    Institute of Scientific and Technical Information of China (English)

    DING Xiaojun; IIJIMA Junichi; HO Sho

    2004-01-01

    While the market potentials and impacts of web-based e-commerce are still in the ascendant, the advances in wireless technologies and mobile networks have brought about a new business opportunity and research attention, what is termed mobile commerce. Commonly, mobile commerce is considered to be another new application of existing web-based e-commerce onto wireless networks, but as an independent business area, mobile commerce has its own advantages and challenges as opposed to traditional e-commerce applications. This paper focuses on exploring the unique features of mobile commerce as. Compared with traditional e-commerce. Also, there are still some limitations arisen in m-commerce in contrast to web-based e-commerce. Finally, current state of mobile commerce in Japan is presented in brief, with an introduction of several cases involving mobile commerce applications in today 's marketplace.

  6. Unique features of space reactors

    International Nuclear Information System (INIS)

    Buden, D.

    1990-01-01

    This paper reports on space reactors that are designed to meet a unique set of requirements; they must be sufficiently compact to be launched in a rocket to their operational location, operate for many years without maintenance and servicing, operate in extreme environments, and reject heat by radiation to space. To meet these restrictions, operating temperatures are much greater than in terrestrial power plants, and the reactors tend to have a fast neutron spectrum. Currently, a new generation of space reactor power plants is being developed. The major effort is in the SP-100 program, where the power plant is being designed for seven years of full power, and no maintenance operation at a reactor outlet operating temperature of 1350 K

  7. The Uniqueness of Islamic Culture

    Directory of Open Access Journals (Sweden)

    Sinan YILMAZ

    2014-12-01

    Full Text Available Abstract This paper examines the main reasons behind why Islamic culture is different than other cultures. In the introduction part of the paper, the usage area of the words culture and civilization were tackled. In the first part of the paper, an evaluation of the uniqueness of Islamic culture was made and examples about this were given. In the second part of the paper, evaluations about how Islamic culture has struggled with modernization and secularization and how it has shaped itself as a result of this were made. In the third part of the paper, the situation in which Islamic civilization has regressed against the Western civilization causing emerging arguments and the current situation in Islamic civilization have been addressed by making evaluations on culture and civilization. In the final part, evaluations on thesis this paper has used were made.

  8. Preparation of Multiwalled Carbon Nanotube-Poly (4-Styrenesulfonic Acid Aqueous Dispersion for Dopamine Sensing

    Directory of Open Access Journals (Sweden)

    Aihua LIU

    2006-12-01

    Full Text Available A simple and facile method for the non-covalent functionalization of multi-walled carbon nanotubes (MWNTs using poly(4-styrenesulfonic acid (PSS is proposed. The resulting PSS-MWNTs dispersion is readily soluble in water and can be left to stand for 2 weeks at room temperature, no phase separation with aggregation of nanotubes at the bottom of the vials was observed. The as-prepared PSS-MWNTs dispersions could facilitate the processing of the nanotubes into composites with high nanotube loading. The PSS-MWNTs complex shows high electrocatalytic activity to the oxidation of neutrontransmitter of dopamine, suggesting that the coating of PSS onto carbon nanotubes surface without destroying the electronic structures of the pristine carbon nanotubes; therefore, the unique properties including the catalytic property of the nanotubes retained. It is envisioned that the PSS-MWNTs aqueous dispersions may find possible applications in the development of biosensors, bioelectronics, separation and environment protection as well as other biological events where water-based environment is required.

  9. Influence of the silicon content on the core corrosion properties of dispersion type fuel plates; Influencia del Contenido en silicio sobre la corrosion acuosa de los nucleos de placas combustibles

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, C; Saenz de Tejada, L M; Diaz Diaz, J

    1969-07-01

    A new process to produce aluminium base dispersion type fuel plates has been developed at the Spanish JEN (Junta de Energia Nuclear). The dispersed fuel material is obtained by an aluminothermic process to render a stoichiometric cermet of UAI{sub 3} and AI{sub 2}O{sub 3} according to the reaction. (Author)

  10. Statistical Physics of Colloidal Dispersions.

    Science.gov (United States)

    Canessa, E.

    Available from UMI in association with The British Library. Requires signed TDF. This thesis is concerned with the equilibrium statistical mechanics of colloidal dispersions which represent useful model systems for the study of condensed matter physics; namely, charge stabilized colloidal dispersions and polymer stabilized colloidal dispersions. A one-component macroparticle approach is adopted in order to treat the macroscopic and microscopic properties of these systems in a simple and comprehensive manner. The thesis opens with the description of the nature of the colloidal state before reviewing some basic definitions and theory in Chapter II. In Chapter III a variational theory of phase equilibria based on the Gibbs-Bogolyobov inequality is applied to sterically stabilized colloidal dispersions. Hard spheres are chosen as the reference system for the disordered phases while an Einstein model is used for the ordered phases. The new choice of pair potential, taken for mathematical convenience, is a superposition of two Yukawa functions. By matching a double Yukawa potential to the van der Waals attractive potential at different temperatures and introducing a purely temperature dependent coefficient to the repulsive part, a rich variety of observed phase separation phenomena is qualitatively described. The behaviour of the potential is found to be consistent with a small decrease of the polymer layer thickness with increasing temperature. Using the same concept of a collapse transition the non-monotonic second virial coefficient is also explained and quantified. It is shown that a reduction of the effective macroparticle diameter with increasing temperature can only be partially examined from the point of view of a (binary-) polymer solution theory. This chapter concludes with the description of the observed, reversible, depletion flocculation behaviour. This is accomplished by using the variational formalism and by invoking the double Yukawa potential to allow

  11. Silicate Dispersion and Mechanical Reinforcement in Polysiloxane/Layered Silicate Nanocomposites

    KAUST Repository

    Schmidt, Daniel F.

    2010-01-12

    We report the first in-depth comparison of the mechanical properties and equilibrium solvent uptake of a range of polysiloxane nanocomposites based on treated and untreated montmorillonite and fumed silica nanofillers. We demonstrate the ability of equilibrium solvent uptake data (and, thus, overall physical and chemical cross-link density) to serve as a proxy for modulus (combining rubber elasticity and Flory-Rehner theory), hardness (via the theory of Boussinesq), and elongation at break, despite the nonideal nature of these networks. In contrast, we find that tensile and tear strength are not well-correlated with solvent uptake. Interfacial strength seems to dominate equilibrium solvent uptake and the mechanical properties it predicts. In the montmorillonite systems in particular, this results in the surprising consequence that equilibrium solvent uptake and mechanical properties are independent of dispersion state. We conclude that edge interactions play a more significant role than degree of exfoliation, a result unique in the field of polymer nanocomposites. This demonstrates that even a combination of polymer/nanofiller compatibility and thermodynamically stable nanofiller dispersion levels may not give rise to reinforcement. These findings provide an important caveat when attempting to connect structure and properties in polymer nanocomposites, and useful guidance in the design of optimized polymer/layered silicate nanocomposites in particular. © 2009 American Chemical Society.

  12. Co-Processed Chitin-Mannitol as a New Excipient for Oro-Dispersible Tablets

    Directory of Open Access Journals (Sweden)

    Nidal Daraghmeh

    2015-03-01

    Full Text Available This study describes the preparation, characterization and performance of a novel excipient for use in oro-dispersible tablets (ODT. The excipient (Cop–CM consists of chitin and mannitol. The excipient with optimal physicochemical properties was obtained at a chitin: mannitol ratio of 2:8 (w/w and produced by roll compaction (RC. Differential scanning calorimetry (DSC, Fourier transform-Infrared (FT-IR, X-ray powder diffraction (XRPD and scanning electron microscope (SEM techniques were used to characterize Cop–CM, in addition to characterization of its powder and ODT dosage form. The effect of particle size distribution of Cop–CM was investigated and found to have no significant influence on the overall tablet physical properties. The compressibility parameter (a for Cop–CM was calculated from a Kawakita plot and found to be higher (0.661 than that of mannitol (0.576 due to the presence of the highly compressible chitin (0.818. Montelukast sodium and domperidone ODTs produced, using Cop–CM, displayed excellent physicochemical properties. The exceptional binding, fast wetting and superdisintegration properties of Cop–CM, in comparison with commercially available co-processed ODT excipients, results in a unique multifunctional base which can successfully be used in the formulation of oro-dispersible and fast immediate release tablets.

  13. Rheological Behavior of Bentonite-Polyester Dispersions

    Science.gov (United States)

    Abu-Jdayil, Basim; Al-Omari, Salah Addin

    2013-07-01

    The rheological behavior of a bentonite clay dispersed in unsaturated polyester was investigated. The effects of the solid content and particle size on the steady and transient rheological properties of the dispersions were studied. In addition, two types of bentonite with different Na+/Ca+2 ratio were used in this study. The Herschel-Bulkley and the Weltman models were used to describe the apparent viscosity of the bentonite-polyester composite in relation to the shear rate and shearing time. The bentonite-polyester dispersions were found to exhibit both Newtonian and non-Newtonian behavior. The transition from a Newtonian to a Bingham plastic and then to a shear-thinning material with a yield stress was found to depend on the solid concentration, the particle size, and the type of bentonite. At a low solid content, the apparent viscosity of the bentonite dispersion increased linearly with solid concentration. But a dramatic increase in the apparent viscosity beyond a solid content of 20 wt.% was observed. On the other hand, a thixotropic behavior was detected in bentonite-polyester dispersions with a high solid content and a low particle size. However, this behavior was more pronounced in dispersions with a high Na+/Ca+2 ratio.

  14. Characterization of Nanoreinforcement Dispersion in Inorganic Nanocomposites: A Review

    Directory of Open Access Journals (Sweden)

    Nouari Saheb

    2014-05-01

    Full Text Available Metal and ceramic matrix composites have been developed to enhance the stiffness and strength of metals and alloys, and improve the toughness of monolithic ceramics, respectively. It is possible to further improve their properties by using nanoreinforcement, which led to the development of metal and ceramic matrix nanocomposites, in which case, the dimension of the reinforcement is on the order of nanometer, typically less than 100 nm. However, in many cases, the properties measured experimentally remain far from those estimated theoretically. This is mainly due to the fact that the properties of nanocomposites depend not only on the properties of the individual constituents, i.e., the matrix and reinforcement as well as the interface between them, but also on the extent of nanoreinforcement dispersion. Therefore, obtaining a uniform dispersion of the nanoreinforcement in the matrix remains a key issue in the development of nanocomposites with the desired properties. The issue of nanoreinforcement dispersion was not fully addressed in review papers dedicated to processing, characterization, and properties of inorganic nanocomposites. In addition, characterization of nanoparticles dispersion, reported in literature, remains largely qualitative. The objective of this review is to provide a comprehensive description of characterization techniques used to evaluate the extent of nanoreinforcement dispersion in inorganic nanocomposites and critically review published work. Moreover, methodologies and techniques used to characterize reinforcement dispersion in conventional composites, which may be used for quantitative characterization of nanoreinforcement dispersion in nanocomposites, is also presented.

  15. Halloysite reinforced epoxy composites with improved mechanical properties

    Directory of Open Access Journals (Sweden)

    Saif Muhammad Jawwad

    2016-03-01

    Full Text Available Halloysite nanotubes (HNTs reinforced epoxy composites with improved mechanical properties were prepared. The prepared HNTs reinforced epoxy composites demonstrated improved mechanical properties especially the fracture toughness and flexural strength. The flexural modulus of nanocomposite with 6% mHNTs loading was 11.8% higher than that of neat epoxy resin. In addition, the nanocomposites showed improved dimensional stability. The prepared halloysite reinforced epoxy composites were characterized by thermal gravimetric analysis (TGA. The improved properties are attributed to the unique characteristics of HNTs, uniform dispersion of reinforcement and interfacial coupling.

  16. Coping with power dispersion?

    DEFF Research Database (Denmark)

    2014-01-01

    The last decades have witnessed a significant shift in policy competences away from central governments in Europe. The reallocation of competences spans over three dimensions: upwards; sideways; and downwards. This collection takes the dispersion of powers as a starting point and seeks to assess...... how the actors involved cope with the new configurations. In this introduction, we discuss the conceptualization of power dispersion and highlight the ways in which the contributions add to this research agenda. We then outline some general conclusions and end by indicating future avenues of research....... Taken together, the collection contributes some answers to the challenge of defining and measuring – in a comparative way – the control and co-ordination mechanisms which power dispersion generates. It also explores the tension between political actors' quest for autonomy and the acknowledgement...

  17. Property.

    Science.gov (United States)

    Piele, Philip K.

    Numerous cases in this year's chapter dealt with the same topics of previous years--contracts and bids for building construction, and detachment and annexation of a portion of a school district. The courts continued to attribute board discretionary authority to school boards in school property matters. Intergovernmental disputes over ownership or…

  18. Non-unique factorizations algebraic, combinatorial and analytic theory

    CERN Document Server

    Geroldinger, Alfred

    2006-01-01

    From its origins in algebraic number theory, the theory of non-unique factorizations has emerged as an independent branch of algebra and number theory. Focused efforts over the past few decades have wrought a great number and variety of results. However, these remain dispersed throughout the vast literature. For the first time, Non-Unique Factorizations: Algebraic, Combinatorial, and Analytic Theory offers a look at the present state of the theory in a single, unified resource.Taking a broad look at the algebraic, combinatorial, and analytic fundamentals, this book derives factorization results and applies them in concrete arithmetical situations using appropriate transfer principles. It begins with a basic introduction that can be understood with knowledge of standard basic algebra. The authors then move to the algebraic theory of monoids, arithmetic theory of monoids, the structure of sets of lengths, additive group theory, arithmetical invariants, and the arithmetic of Krull monoids. They also provide a s...

  19. Interface, a dispersed architecture

    NARCIS (Netherlands)

    Vissers, C.A.

    1976-01-01

    Past and current specification techniques use timing diagrams and written text to describe the phenomenology of an interface. This paper treats an interface as the architecture of a number of processes, which are dispersed over the related system parts and the message path. This approach yields a

  20. Psychorheology of food dispersions

    Czech Academy of Sciences Publication Activity Database

    Štern, Petr; Panovská, Z.; Pokorný, J.

    2010-01-01

    Roč. 58, č. 1 (2010), s. 29-35 ISSN 0042-790X R&D Projects: GA AV ČR IAA2060404 Institutional research plan: CEZ:AV0Z20600510 Keywords : psychorheology * food dispersions * tomato ketchup * rheology * sensory analysis Subject RIV: BK - Fluid Dynamics Impact factor: 0.553, year: 2010

  1. Dispersal of sticky particles

    Science.gov (United States)

    Reddy, Ramana; Kumar, Sanjeev

    2007-12-01

    In this paper, we show through simulations that when sticky particles are broken continually, particles are dispersed into fine dust only if they are present in a narrow range of volume fractions. The upper limit of this range is 0.20 in the 2D and 0.10 in the 3D space. An increase in the dimensionality of space reduces the upper limit nearly by a factor of two. This scaling holds for dispersal of particles in hyperdimensional space of dimensions up to ten, the maximum dimension studied in this work. The maximum values of volume fractions obtained are significantly lower than those required for close packing and random packing of discs in 2D and spheres in 3D space. These values are also smaller than those required for critical phenomena of cluster percolation. The results obtained are attributed to merger cascades of sticky particles, triggered by breakup events. A simple theory that incorporates this cascade is developed to quantitatively explain the observed scaling of the upper limit with the dimensionality of space. The theory also captures the dynamics of the dispersal process in the corresponding range of particle volume fractions. The theory suggests that cascades of order one and two predominantly decide the upper limit for complete dispersal of particles.

  2. Novel applications of the dispersive optical model

    Science.gov (United States)

    Dickhoff, W. H.; Charity, R. J.; Mahzoon, M. H.

    2017-03-01

    A review of recent developments of the dispersive optical model (DOM) is presented. Starting from the original work of Mahaux and Sartor, several necessary steps are developed and illustrated which increase the scope of the DOM allowing its interpretation as generating an experimentally constrained functional form of the nucleon self-energy. The method could therefore be renamed as the dispersive self-energy method. The aforementioned steps include the introduction of simultaneous fits of data for chains of isotopes or isotones allowing a data-driven extrapolation for the prediction of scattering cross sections and level properties in the direction of the respective drip lines. In addition, the energy domain for data was enlarged to include results up to 200 MeV where available. An important application of this work was implemented by employing these DOM potentials to the analysis of the (d, p) transfer reaction using the adiabatic distorted wave approximation. We review these calculations which suggest that physically meaningful results are easier to obtain by employing DOM ingredients as compared to the traditional approach which relies on a phenomenologically-adjusted bound-state wave function combined with a global (nondispersive) optical-model potential. Application to the exotic 132Sn nucleus also shows great promise for the extrapolation of DOM potentials towards the drip line with attendant relevance for the physics of FRIB. We note that the DOM method combines structure and reaction information on the same footing providing a unique approach to the analysis of exotic nuclei. We illustrate the importance of abandoning the custom of representing the non-local Hartree-Fock (HF) potential in the DOM by an energy-dependent local potential as it impedes the proper normalization of the solution of the Dyson equation. This important step allows for the interpretation of the DOM potential as representing the nucleon self-energy permitting the calculations of

  3. Introduction to nonlinear dispersive equations

    CERN Document Server

    Linares, Felipe

    2015-01-01

    This textbook introduces the well-posedness theory for initial-value problems of nonlinear, dispersive partial differential equations, with special focus on two key models, the Korteweg–de Vries equation and the nonlinear Schrödinger equation. A concise and self-contained treatment of background material (the Fourier transform, interpolation theory, Sobolev spaces, and the linear Schrödinger equation) prepares the reader to understand the main topics covered: the initial-value problem for the nonlinear Schrödinger equation and the generalized Korteweg–de Vries equation, properties of their solutions, and a survey of general classes of nonlinear dispersive equations of physical and mathematical significance. Each chapter ends with an expert account of recent developments and open problems, as well as exercises. The final chapter gives a detailed exposition of local well-posedness for the nonlinear Schrödinger equation, taking the reader to the forefront of recent research. The second edition of Introdu...

  4. Dispersivity in heterogeneous permeable media

    International Nuclear Information System (INIS)

    Chesnut, D.A.

    1994-01-01

    When one fluid displaces another through a one-dimensional porous medium, the composition changes from pure displacing fluid at the inlet to pure displaced fluid some distance downstream. The distance over which an arbitrary percentage of this change occurs is defined as the mixing zone length, which increases with increasing average distance traveled by the displacement front. For continuous injection, the mixing zone size can be determined from a breakthrough curve as the time required for the effluent displacing fluid concentration to change from, say, 10% to 90%. In classical dispersion theory, the mixing zone grows in proportion to the square root of the mean distance traveled, or, equivalently, to the square root of the mean breakthrough time. In a multi-dimensional heterogeneous medium, especially at field scales, the size of the mixing zone grows almost linearly with mean distance or travel time. If an observed breakthrough curve is forced to fit the, clinical theory, the resulting effective dispersivity, instead of being constant, also increases almost linearly with the spatial or temporal scale of the problem. This occurs because the heterogeneity in flow properties creates a corresponding velocity distribution along the different flow pathways from the inlet to the outlet of the system. Mixing occurs mostly at the outlet, or wherever the fluid is sampled, rather than within the medium. In this paper, we consider the effects. of this behavior on radionuclide or other contaminant migration

  5. Dispersivity in heterogeneous permeable media

    International Nuclear Information System (INIS)

    Chesnut, D.A.

    1994-01-01

    When one fluid displaces another through a one-dimensional porous medium, the composition changes from pure displacing fluid at the inlet to pure displaced fluid some distance downstream. The distance over which an arbitrary percentage (typically 80%) of this change occurs is defined as the mixing zone length, which increases with increasing average distance traveled by the displacement front. Alternatively, for continuous injection, the mixing zone size can be determined from a breakthrough curve as the time required for the effluent displacing fluid concentration to change from, say, 10% to 90%. In classical dispersion theory, the mixing zone grows in proportion to the square root of the mean distance traveled, or, equivalently, to the square root of the mean breakthrough time. In a multi-dimensional heterogeneous medium, especially at field scales, the size of the mixing zone grows almost linearly with mean distance or travel time. If an observed breakthrough curve is forced to fit the classical theory, the resulting effective dispersivity, instead of being constant, also increases almost linearly with the spatial or temporal scale of the problem. This occurs because the heterogeneity in flow properties creates a corresponding velocity distribution along the different flow pathways from the inlet to the outlet of the system. Mixing occurs mostly at the outlet, or wherever the fluid is sampled, rather than within the medium. In this paper, we consider the effects of this behavior on radionuclide or other contaminant migration

  6. Multilayer cladding with hyperbolic dispersion for plasmonic waveguides

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Shalaginov, Mikhail Y.; Ishii, Satoshi

    2015-01-01

    We study the properties of plasmonic waveguides with a dielectric core and multilayer metal-dielectric claddings that possess hyperbolic dispersion. The waveguides hyperbolic multilayer claddings show better performance in comparison to conventional plasmonic waveguides. © OSA 2015....

  7. Fabrication and properties of shape-memory polymer coated with conductive nanofiber paper

    Science.gov (United States)

    Lu, Haibao; Liu, Yanju; Gou, Jan; Leng, Jinsong

    2009-07-01

    A unique concept of shape-memory polymer (SMP) nanocomposites making up of carbon nanofiber paper was explored. The essential element of this method was to design and fabricate nanopaper with well-controlled and optimized network structure of carbon nanofibers. In this study, carbon nanofiber paper was prepared under ultrasonicated processing and vapor press method, while the dispersion of nanofiber was treated by BYK-191 dispersant. The morphologies of carbon nanofibers within the paper were characterized with scanning electron microscopy (SEM). In addition, the thermomechanical properties of SMP coated with carbon nanofiber paper were measured by the dynamic mechanical thermal analysis (DMTA). It was found that the glass transition temperature and thermomechanical properties of nanocomposites were strongly determined by the dispersion of polymer in conductive paper. Subsequently, the electrical conductivity of conductive paper and nanocomposites were measured, respectively. And experimental results revealed that the conductive properties of nanocoposites were significantly improved by carbon nanopaper, resulting in actuation driven by electrical resistive heating.

  8. Plume dispersion in four pine thinning scenarios: development of a simple pheromone dispersion model

    Science.gov (United States)

    Holly Peterson; Harold Thistle; Brian Lamb; Gene Allwine; Steve Edburg; Brian Strom

    2010-01-01

    A unique field campaign was conducted in 2004 to examine how changes in stand density may affect dispersion of insect pheromones in forest canopies. Over a l4-day period, 126 tracer tests were performed, and conditions ranged from an unthinned loblolly pine (Pinus taeda) canopy through a series of thinning scenarios with basal areas of32.l, 23.0, and 16.1 m2ha-l.ln...

  9. Determining hydraulic parameters of a karst aquifer using unique ...

    African Journals Online (AJOL)

    Although karst aquifers constitute some of the most important water resources worldwide, generally accepted methods for reliably characterising their hydraulic properties are still elusive. This paper aims at contributing to the discussion by a first-ever attempt to utilise various sets of unique historical data derived from ...

  10. Microstructure characterization and magnetic properties of nano structured materials

    International Nuclear Information System (INIS)

    Sun, X.C.

    2000-01-01

    The present thesis deals with the unique microstructural properties and their novel magnetic properties of core-shell Ni-Ce nano composite particles, carbon encapsulated Fe, Co, and Ni nanoparticles and the nano crystallization behavior of typical ferromagnetic Fe 78 Si 9 B 13 ribbons. These properties have intensively been investigated by high resolution transmission electron microscopy (HREM), X-ray diffraction (XRD), scanning electron microscopy (Sem), X-ray energy dispersive spectroscopy (Eds.); selected area electron diffraction pattern (SAED), Ft-IR, differential scanning calorimeter (DSC). In addition, magnetic moments measurements at different temperatures and applied fields have been performed by transmission Moessbauer spectroscopy, superconducting quantum interference device magnetometer (SQUID), and vibrating sample magnetometer (VSM). The present studies may provide the insights for the better understanding of the correlation between the unique microstructure and novel magnetic properties for several magnetic nano structured materials. (Author)

  11. Microstructure characterization and magnetic properties of nano structured materials

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.C

    2000-07-01

    The present thesis deals with the unique microstructural properties and their novel magnetic properties of core-shell Ni-Ce nano composite particles, carbon encapsulated Fe, Co, and Ni nanoparticles and the nano crystallization behavior of typical ferromagnetic Fe{sub 78}Si{sub 9}B{sub 13} ribbons. These properties have intensively been investigated by high resolution transmission electron microscopy (HREM), X-ray diffraction (XRD), scanning electron microscopy (Sem), X-ray energy dispersive spectroscopy [eds.]; selected area electron diffraction pattern (SAED), Ft-IR, differential scanning calorimeter (DSC). In addition, magnetic moments measurements at different temperatures and applied fields have been performed by transmission Moessbauer spectroscopy, superconducting quantum interference device magnetometer (SQUID), and vibrating sample magnetometer (VSM). The present studies may provide the insights for the better understanding of the correlation between the unique microstructure and novel magnetic properties for several magnetic nano structured materials. (Author)

  12. Unique Fock quantization of scalar cosmological perturbations

    Science.gov (United States)

    Fernández-Méndez, Mikel; Mena Marugán, Guillermo A.; Olmedo, Javier; Velhinho, José M.

    2012-05-01

    We investigate the ambiguities in the Fock quantization of the scalar perturbations of a Friedmann-Lemaître-Robertson-Walker model with a massive scalar field as matter content. We consider the case of compact spatial sections (thus avoiding infrared divergences), with the topology of a three-sphere. After expanding the perturbations in series of eigenfunctions of the Laplace-Beltrami operator, the Hamiltonian of the system is written up to quadratic order in them. We fix the gauge of the local degrees of freedom in two different ways, reaching in both cases the same qualitative results. A canonical transformation, which includes the scaling of the matter-field perturbations by the scale factor of the geometry, is performed in order to arrive at a convenient formulation of the system. We then study the quantization of these perturbations in the classical background determined by the homogeneous variables. Based on previous work, we introduce a Fock representation for the perturbations in which: (a) the complex structure is invariant under the isometries of the spatial sections and (b) the field dynamics is implemented as a unitary operator. These two properties select not only a unique unitary equivalence class of representations, but also a preferred field description, picking up a canonical pair of field variables among all those that can be obtained by means of a time-dependent scaling of the matter field (completed into a linear canonical transformation). Finally, we present an equivalent quantization constructed in terms of gauge-invariant quantities. We prove that this quantization can be attained by a mode-by-mode time-dependent linear canonical transformation which admits a unitary implementation, so that it is also uniquely determined.

  13. [Effect of the crystallization conditions of tetracycline base on the properties of the powders and drug forms obtained. The dependence of the degree of dispersion of tetracycline base on the crystallization conditions].

    Science.gov (United States)

    Lin'kov, G I; Zhukovskaia, S A; Dzhabarov, D N; Nabokov, V S

    1977-09-01

    Characteristics of the powder dispersity of tetracycline base samples prepared by directed crystallization with variation of the process conditions were determined by the sedimentation method. It was found that the speed of the solution agitation had the maximum effect on the level and nature of the dispersity. The rate of the solution temperature and pH changing during the crystallization process had also a significant effect at low agitation speed.

  14. Forging Oxide-Dispersion-Strengthened Superalloys

    Science.gov (United States)

    Harf, F. H.; Glasgow, T. K.; Moracz, D. J.; Austin, C. M.

    1986-01-01

    Cladding of mild steel prevents surface cracking when alloy contacts die. Continual need for improvements in properties of alloys capable of withstanding elevated temperatures. Accomplished by using oxide-dispersion-strengthed superalloys such as Inconel Alloy MA 6000. Elevated tensile properties of forged alloy equal those of hot-rolled MA 6000 bar. Stress-rupture properties somewhat lower than those of bar stock but, at 1,100 degrees C, exceed those of strongest commercial single crystal, directionally solidified and conventionally cast superalloys.

  15. Heart Failure: Unique to Older Adults

    Science.gov (United States)

    ... to Z › Heart Failure › Unique to Older Adults Font size A A A Print Share Glossary Unique ... will suffer from depression at some point. This type of severe depression is more serious than the ...

  16. Computational topology and the Unique Games Conjecture

    OpenAIRE

    Grochow, Joshua A.; Tucker-Foltz, Jamie

    2018-01-01

    Covering spaces of graphs have long been useful for studying expanders (as "graph lifts") and unique games (as the "label-extended graph"). In this paper we advocate for the thesis that there is a much deeper relationship between computational topology and the Unique Games Conjecture. Our starting point is Linial's 2005 observation that the only known problems whose inapproximability is equivalent to the Unique Games Conjecture - Unique Games and Max-2Lin - are instances of Maximum Section of...

  17. Chemical dispersibility testing of fresh and weathered oils

    International Nuclear Information System (INIS)

    Brandvik, P.J.; Daling, P.S.; Aareskjold, K.

    1991-05-01

    This activity in the DIspersants on Weathered Oils-project (DIWO) is a continuation and an extended study of the dispersibility study described in DIWO report No. 3. The main objective has been to study the chemical dispersibility of fresh and weathered oils produced or transported in Norwegian waters. Other important aims of this study have been: To correlate the effectiveness results obtained by three different laboratory methods; to determine the relationship between the dispersant effectiveness and the change in the oils' physico-chemical properties due to weathering (topping, photo-oxidation and w/o-emulsification). This study has been performed with 8 different oil types and 12 different weathering degrees of each oil type. The work performed clearly demonstrates that the oil type and especially the weathering properties are essential for the performance of dispersants at sea. 41 figs., 5 tabs., 16 refs

  18. Dispersion and stabilization of cochleate nanoparticles.

    Science.gov (United States)

    Bozó, Tamás; Wacha, András; Mihály, Judith; Bóta, Attila; Kellermayer, Miklós S Z

    2017-08-01

    Cochleates, calcium-stabilized membrane rolls of nanoscale diameter, promise a unique and efficient way of delivering lipid-soluble drugs, proteins or nucleic acids into biological systems because they protect the encapsulated material against enzymatic or chemical degradation. Self-aggregation, which typically arises during production and storage is a major obstacle that has so far precluded the development of an efficient cochleate-based drug-delivery system. Here we show that citric acid, added transiently in a narrow concentration range, effectively disperses cochleate aggregates, stabilizes the disperse state for long-term storage and preserves the canonical ultrastructure and topological characteristics of cochleate nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Adsorption factor effect on dispersive ability of polymethylmethylmethacrylate

    International Nuclear Information System (INIS)

    Gorokhovskij, G.A.; Samsonov, G.V.; Gorshunov, V.P.

    1977-01-01

    A relationhsip between the rate of polymer macromolecules absorption on some refractory compounds and the dispersion ability of polymer-abrasive compositions was investigated at various contents of the polymethacrylate polymer in an abrasive composition. The solid phase used was powders of Al 2 O 3 , WC, W 2 B 5 , TiB 2 . It was established that the dispersion ability of the polymer-abrasive compositions was a function not only of the cutting properties of the abrasives and the dispersion ability of the polymers, but also of the adsorption properties of the solid phase and of its capacity to transport macromolecules to the surface being worked

  20. In and out of Madagascar: Dispersal to Peripheral Islands, Insular Speciation and Diversification of Indian Ocean Daisy Trees (Psiadia, Asteraceae)

    Science.gov (United States)

    Strijk, Joeri S.; Noyes, Richard D.; Strasberg, Dominique; Cruaud, Corinne; Gavory, Fredéric; Chase, Mark W.; Abbott, Richard J.; Thébaud, Christophe

    2012-01-01

    Madagascar is surrounded by archipelagos varying widely in origin, age and structure. Although small and geologically young, these archipelagos have accumulated disproportionate numbers of unique lineages in comparison to Madagascar, highlighting the role of waif-dispersal and rapid in situ diversification processes in generating endemic biodiversity. We reconstruct the evolutionary and biogeographical history of the genus Psiadia (Asteraceae), a plant genus with near equal numbers of species in Madagascar and surrounding islands. Analyzing patterns and processes of diversification, we explain species accumulation on peripheral islands and aim to offer new insights on the origin and potential causes for diversification in the Madagascar and Indian Ocean Islands biodiversity hotspot. Our results provide support for an African origin of the group, with strong support for non-monophyly. Colonization of the Mascarenes took place by two evolutionary distinct lineages from Madagascar, via two independent dispersal events, each unique for their spatial and temporal properties. Significant shifts in diversification rate followed regional expansion, resulting in co-occurring and phenotypically convergent species on high-elevation volcanic slopes. Like other endemic island lineages, Psiadia have been highly successful in dispersing to and radiating on isolated oceanic islands, typified by high habitat diversity and dynamic ecosystems fuelled by continued geological activity. Results stress the important biogeographical role for Rodrigues in serving as an outlying stepping stone from which regional colonization took place. We discuss how isolated volcanic islands contribute to regional diversity by generating substantial numbers of endemic species on short temporal scales. Factors pertaining to the mode and tempo of archipelago formation and its geographical isolation strongly govern evolutionary pathways available for species diversification, and the potential for successful

  1. In and out of Madagascar: dispersal to peripheral islands, insular speciation and diversification of Indian Ocean daisy trees (Psiadia, Asteraceae.

    Directory of Open Access Journals (Sweden)

    Joeri S Strijk

    Full Text Available Madagascar is surrounded by archipelagos varying widely in origin, age and structure. Although small and geologically young, these archipelagos have accumulated disproportionate numbers of unique lineages in comparison to Madagascar, highlighting the role of waif-dispersal and rapid in situ diversification processes in generating endemic biodiversity. We reconstruct the evolutionary and biogeographical history of the genus Psiadia (Asteraceae, a plant genus with near equal numbers of species in Madagascar and surrounding islands. Analyzing patterns and processes of diversification, we explain species accumulation on peripheral islands and aim to offer new insights on the origin and potential causes for diversification in the Madagascar and Indian Ocean Islands biodiversity hotspot. Our results provide support for an African origin of the group, with strong support for non-monophyly. Colonization of the Mascarenes took place by two evolutionary distinct lineages from Madagascar, via two independent dispersal events, each unique for their spatial and temporal properties. Significant shifts in diversification rate followed regional expansion, resulting in co-occurring and phenotypically convergent species on high-elevation volcanic slopes. Like other endemic island lineages, Psiadia have been highly successful in dispersing to and radiating on isolated oceanic islands, typified by high habitat diversity and dynamic ecosystems fuelled by continued geological activity. Results stress the important biogeographical role for Rodrigues in serving as an outlying stepping stone from which regional colonization took place. We discuss how isolated volcanic islands contribute to regional diversity by generating substantial numbers of endemic species on short temporal scales. Factors pertaining to the mode and tempo of archipelago formation and its geographical isolation strongly govern evolutionary pathways available for species diversification, and the

  2. Dispersed flow film boiling

    International Nuclear Information System (INIS)

    Andreani, M.; Yadigaroglu, G.

    1989-12-01

    Dispersed flow film boiling is the heat transfer regime that occurs at high void fractions in a heated channel. The way this transfer mode is modelled in the NRC computer codes (RELAP5 and TRAC) and the validity of the assumption and empirical correlations used is discussed. An extensive review of the theoretical and experimental work related with heat transfer to highly dispersed mixtures reveals the basic deficiencies of these models: the investigation refers mostly to the typical conditions of low rate bottom reflooding, since the simulation of this physical situation by the computer codes has often showed poor results. The alternative models that are available in the literature are reviewed, and their merits and limits are highlighted. The modification that could improve the physics of the models implemented in the codes are identified. (author) 13 figs., 123 refs

  3. Working document dispersion models

    International Nuclear Information System (INIS)

    Dop, H. van

    1988-01-01

    This report is a summary of the most important results from June 1985 of the collaboration of the RIVM (Dutch National Institute for Public Health and Environment Hygiene) and KNMI (Royal Dutch Meteorologic Institute) on the domain of dispersion models. It contains a short description of the actual SO x /NO x -model. Furthermore it contains recommendations for modifications of some numerical-mathematical aspects and an impulse to a more complete description of chemical processes in the atmosphere and the (wet) deposition process. A separate chapter is devoted to the preparation of meteorologic data which are relevant for dispersion as well as atmospheric chemistry and deposition. This report serves as working document for the final formulation of a acidifying- and oxidant-model. (H.W.). 69 refs.; 51 figs.; 13 tabs.; 3 schemes

  4. Spatially Dispersed Employee Recovery

    DEFF Research Database (Denmark)

    Hvass, Kristian Anders; Torfadóttir, Embla

    2014-01-01

    Employee recovery addresses either employee well-being or management's practices in aiding employees in recovering themselves following a service failure. This paper surveys the cabin crew at a small, European, low-cost carrier and investigates employees' perceptions of management practices to aid...... personnel achieve service recovery. Employee recovery within service research often focuses on front-line employees that work in a fixed location, however a contribution to the field is made by investigating the recovery of spatially dispersed personnel, such as operational personnel in the transport sector......, who have a work place away from a fixed or central location and have minimal management contact. Results suggest that the support employees receive from management, such as recognition, information sharing, training, and strategic awareness are all important for spatially dispersed front...

  5. Heat dispersion in rivers

    International Nuclear Information System (INIS)

    Shaw, T.L.

    1974-01-01

    One of the tasks of the Sonderforschungsbereich 80 is to study the dispersion of heat discharged into rivers and other bodies of water and to develop methods which permit prediction of detrimental effects caused by the heated discharges. In order to help the SFB 80 to specify this task, Dr. Shaw, lecturer of Civil Engineering at the Bristol University, conducted a literature survey on heat-dispersion studies during the two months which he spent as a visiting research fellow with the SFB 80 at the University of Karlsruhe in the summer of 1973. The following report is the outcome of this survey. It gives Dr. Shaw's assessment of the present state of knowledge - based almost exclusively on literature in the English language - and compares this with the knowledge required by river planners. The apparent discrepancy leads to suggestions for future research. Selected references as well as a representative bibliography can be found at the end of the report. (orig.) [de

  6. Meat production and quality two unique properties of young camels

    Directory of Open Access Journals (Sweden)

    M. N. Bakkar

    2000-02-01

    Full Text Available Eighteen one-hump black (Majaheem young camels were used to study growth rate and carcass percentage. The animals were selected and bought of similar age (about six months and weight (around 150 kg. They were assigned randomly into three feeding groups. Each group was fed two types of rations: (A concentrated pellets 18% crude protein at the rate of 1.5% CWT; and (B one of three types of roughage: (a alfalfa hay, (b Rhodes grass hay, or (c wheat straw treated with ammonia gas. Roughage was weighed and fed ad libitum. The experiment was ended when anirnals were about 14 months of age. Average body weights were 315, 298.8 and 291.4 kg for the three groups, respectively. Average daily gains for the three respective groups were 932, 803 and 767 g per day. Average carcass weights/kg (and carcass percentages of each group were 180.6 (57.3% for alfalfa, 170.7 (57.1% for Rhodes and 168.1 (57.7% for treated straw. Average forequarters weights/kg (and percentages to the carcass were 98.9 (54.8%, 95.6 (56% and 88.1 (52.4% for the three groups, respectively. The hindquarters average weights/kg (and percentages for the three respective groups were: 81,7 (45.2%, 75.1 (44% and 80 (47.6%. Eight-year records (1986-1994 on carcasses of carnels, cattle and sheep were obtained from Riyadh Modem Slaughterhouse. The total number of animals killed was 3,891,301. Comparisons were made between the number of anirnals killed and the number of carcasses destroyed for each of the three species. It was found that on average for every carnel carcass destroyed 12 carcasses of cattle and 19 carcasses of sheep were destroyed. These results show clearly that camels produce the most hygienic meat for human consumption in comparison with cattle and sheep.

  7. A deep-sea bacterium with unique nitrifying property

    Digital Repository Service at National Institute of Oceanography (India)

    Ram, A.; LokaBharathi, P.A.; Nair, S.; Chandramohan, D.

    assay (chemical assay). Bianchi et al . 10 had shown that the a c tivity determined by chemical assay was comparable to 15 N method. For the present study we used only the chemical assay. The activity in terms of ammonia and nitrite conversion... s tributed in the marine environment, the number of nitrif i ers mediating this process has rarely been deter - mined. N i trification is generally carried out by known nitrifiers which either oxidize ammonia to nit rite (Phase I) or nitrite to nitrate...

  8. Does Light from Steady Sources Bear Any Observable Imprint of the Dispersive Intergalactic Medium?

    Science.gov (United States)

    Lieu, Richard; Duan, Lingze

    2018-02-01

    There has recently been some interest in the prospect of detecting ionized intergalactic baryons by examining the properties of incoherent light from background cosmological sources, namely quasars. Although the paper by Lieu et al. proposed a way forward, it was refuted by the later theoretical work of Hirata & McQuinn and the observational study of Hales et al. In this paper we investigate in detail the manner in which incoherent radiation passes through a dispersive medium both from the frameworks of classical and quantum electrodynamics, leading us to conclude that the premise of Lieu et al. would only work if the pulses involved are genuinely classical ones containing many photons per pulse; unfortunately, each photon must not be treated as a pulse that is susceptible to dispersive broadening. We are nevertheless able to change the tone of the paper at this juncture by pointing out that because current technology allows one to measure the phase of individual modes of radio waves from a distant source, the most reliable way of obtaining irrefutable evidence of dispersion, namely via the detection of its unique signature of a quadratic spectral phase, may well be already accessible. We demonstrate how this technique is only applied to measure the column density of the ionized intergalactic medium.

  9. Elastic-resilience-induced dispersion of carbon nanotubes: a novel way of fabricating high performance elastomer

    International Nuclear Information System (INIS)

    Wu, Siwu; Lin, Tengfei; Guo, Baochun

    2013-01-01

    State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs. (paper)

  10. Seed dispersal increases local species richness and reduces spatial turnover of tropical tree seedlings.

    Science.gov (United States)

    Wandrag, Elizabeth M; Dunham, Amy E; Duncan, Richard P; Rogers, Haldre S

    2017-10-03

    Dispersal is thought to be a key process underlying the high spatial diversity of tropical forests. Just how important dispersal is in structuring plant communities is nevertheless an open question because it is very difficult to isolate dispersal from other processes, and thereby measure its effect. Using a unique situation, the loss of vertebrate seed dispersers on the island of Guam and their presence on the neighboring islands of Saipan and Rota, we quantify the contribution of vertebrate seed dispersal to spatial patterns of diversity of tree seedlings in treefall gaps. The presence of vertebrate seed dispersers approximately doubled seedling species richness within canopy gaps and halved species turnover among gaps. Our study demonstrates that dispersal plays a key role in maintaining local and regional patterns of diversity, and highlights the potential for ongoing declines in vertebrate seed dispersers to profoundly alter tropical forest composition.

  11. Nanoparticles in Polymers: Assembly, Rheology and Properties

    Science.gov (United States)

    Rao, Yuanqiao

    Inorganic nanoparticles have the potential of providing functionalities that are difficult to realize using organic materials; and nanocomposites is an effective mean to impart processibility and construct bulk materials with breakthrough properties. The dispersion and assembly of nanoparticles are critical to both processibility and properties of the resulting product. In this talk, we will discuss several methods to control the hierarchical structure of nanoparticles in polymers and resulting rheological, mechanical and optical properties. In one example, polymer-particle interaction and secondary microstructure were designed to provide a low viscosity composition comprising exfoliated high aspect ratio clay nanoparticles; in another example, the microstructure control through templates was shown to enable unique thermal mechanical and optical properties. Jeff Munro, Stephanie Potisek, Phillip Hustad; all of the Dow Chemical Company are co-authors.

  12. Structural properties of small Lin (n = 5-8) atomic clusters via ab initio random structure searching: A look into the role of different implementations of long-range dispersion corrections

    Science.gov (United States)

    Putungan, Darwin Barayang; Lin, Shi-Hsin

    2018-01-01

    In this work, we looked into the lowest energy structures of small lithium clusters (Lin, n = 5, 6, 7, 8) utilizing conventional PBE exchange-correlation functional, PBE with D2 dispersion correction and PBE with Tkatchenko and Scheffler (TS) dispersion correction, and searched using ab initio random structure searching. Results show that in general, dispersion-corrected PBE obtained similar lowest minima structures as those obtained via conventional PBE regardless of the type of implementation, although both D2 and TS found several high-energy isomers that conventional PBE did not arrive at, with TS in general giving more structures per energy range that could be attributed to its environment-dependent implementation. Moreover, D2 and TS dispersion corrections found a lowest energy geometry for Li8 cluster that is in agreement with the structure obtained via the typical benchmarking method diffusion Monte Carlo in a recent work. It is thus suggested that for much larger lithium clusters, utilization of dispersion correction could be of help in searching for lowest energy minima that is in close agreement with that of diffusion Monte Carlo results, but computationally inexpensive.

  13. Scaling of Natal Dispersal Distances in Terrestrial Birds and Mammals

    Directory of Open Access Journals (Sweden)

    Glenn D. Sutherland

    2000-07-01

    Full Text Available Natal dispersal is a process that is critical in the spatial dynamics of populations, including population spread, recolonization, and gene flow. It is a central focus of conservation issues for many vertebrate species. Using data for 77 bird and 68 mammal species, we tested whether median and maximum natal dispersal distances were correlated with body mass, diet type, social system, taxonomic family, and migratory status. Body mass and diet type were found to predict both median and maximum natal dispersal distances in mammals: large species dispersed farther than small ones, and carnivorous species dispersed farther than herbivores and omnivores. Similar relationships occurred for carnivorous bird species, but not for herbivorous or omnivorous ones. Natal dispersal distances in birds or mammals were not significantly related to broad categories of social systems. Only in birds were factors such as taxonomic relatedness and migratory status correlated with natal dispersal, and then only for maximum distances. Summary properties of dispersal processes appeared to be derived from interactions among behavioral and morphological characteristics of species and from their linkages to the dynamics of resource availability in landscapes. In all the species we examined, most dispersers moved relatively short distances, and long-distance dispersal was uncommon. On the basis of these findings, we fit an empirical model based on the negative exponential distribution for calculating minimum probabilities that animals disperse particular distances from their natal areas. This model, coupled with knowledge of a species' body mass and diet type, can be used to conservatively predict dispersal distances for different species and examine possible consequences of large-scale habitat alterations on connectedness between populations. Taken together, our results can provide managers with the means to identify species vulnerable to landscape-level habitat changes

  14. Equilibrium Price Dispersion in a Matching Model with Divisible Money

    NARCIS (Netherlands)

    Kamiya, K.; Sato, T.

    2002-01-01

    The main purpose of this paper is to show that, for any given parameter values, an equilibrium with dispersed prices (two-price equilibrium) exists in a simple matching model with divisible money presented by Green and Zhou (1998).We also show that our two-price equilibrium is unique in certain

  15. Nozzle for electric dispersion reactor

    Science.gov (United States)

    Sisson, W.G.; Basaran, O.A.; Harris, M.T.

    1995-11-07

    A nozzle for an electric dispersion reactor includes two concentric electrodes, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 4 figs.

  16. Synthesis and properties of layered synthetic microstructure (LSM) dispersion elements for 62 eV (200A) to 1.24 keV (10A) radiation. Final report

    International Nuclear Information System (INIS)

    Barbee, T.W. Jr.

    1981-08-01

    The opportunities offered by engineered synthetic multilayer dispersion elements for x-rays have been recognized since the earliest days of x-ray diffraction analysis. In this paper, application of sputter deposition technology to the synthesis of Layered Synthetic Microstructure (LSMs) of sufficient quality for use as x-ray dispersion elements is discussed. It will be shown that high efficiency, controllable bandwidth dispersion elements, with d spacings varying from 15 A to 180 A, may be synthesized onto both mechanically stiff and flexible substrates. Multilayer component materials include tungsten, niobium, molybdenum, titanium, vanadium, and silicon layers separated by carbon layers. Experimental observations of peak reflectivity in first order, integrated reflectivity in first order, and diffraction performance at selected photon energies in the range, 100 to 15,000 eV, are reported and compared to theory

  17. Attenuation and velocity dispersion in the exploration seismic frequency band

    Science.gov (United States)

    Sun, Langqiu

    In an anelastic medium, seismic waves are distorted by attenuation and velocity dispersion, which depend on petrophysical properties of reservoir rocks. The effective attenuation and velocity dispersion is a combination of intrinsic attenuation and apparent attenuation due to scattering, transmission response, and data acquisition system. Velocity dispersion is usually neglected in seismic data processing partly because of insufficient observations in the exploration seismic frequency band. This thesis investigates the methods of measuring velocity dispersion in the exploration seismic frequency band and interprets the velocity dispersion data in terms of petrophysical properties. Broadband, uncorrelated vibrator data are suitable for measuring velocity dispersion in the exploration seismic frequency band, and a broad bandwidth optimizes the observability of velocity dispersion. Four methods of measuring velocity dispersion in uncorrelated vibrator VSP data are investigated, which are the sliding window crosscorrelation (SWCC) method, the instantaneous phase method, the spectral decomposition method, and the cross spectrum method. Among them, the SWCC method is a new method and has satisfactory robustness, accuracy, and efficiency. Using the SWCC method, velocity dispersion is measured in the uncorrelated vibrator VSP data from three areas with different geological settings, i.e., Mallik gas hydrate zone, McArthur River uranium mines, and Outokumpu crystalline rocks. The observed velocity dispersion is fitted to a straight line with respect to log frequency for a constant (frequency-independent) Q value. This provides an alternative method for calculating Q. A constant Q value does not directly link to petrophysical properties. A modeling study is implemented for the Mallik and McArthur River data to interpret the velocity dispersion observations in terms of petrophysical properties. The detailed multi-parameter petrophysical reservoir models are built according to

  18. Structural investigation of biogenic ferrihydrite nanoparticles dispersion

    International Nuclear Information System (INIS)

    Balasoiu, M.; Ishchenko, L.A.; Stolyar, S.V.; Iskhakov, R.S.; Rajkher, Yu.L.; Kuklin, A.I.; Solov'ev, D.V.; Arzumanyan, G.M.; Kurkin, T.S.; Aranghel, D.

    2010-01-01

    Structural properties of biogenic ferrihydrite nanoparticles produced by bacteria Klebsiella oxytoca are investigated. Investigations of morphology and size of particles dispersed in water by means of high-resolution transmission electron microscopy and small angle X-ray scattering measurements were performed. By model calculations followed by fitting procedure the structural parameters of a cylinder of radius R = (4.87 ± 0.02) nm and height L = (2.12 ± 0.04) nm are obtained

  19. Plasma Dispersion Functions for Complex Frequencies

    International Nuclear Information System (INIS)

    Pavlov, S. S.; Castejon, F.

    2005-01-01

    Plasma dispersion functions for complex wave propagation frequency in the weak relativistic regime for arbitrary longitudinal refractive index are estimated and presented in this work. These functions, that are know as Shkarofsky functions in the case of real frequency, are estimated using a new method that avoids the singularities that appear in previous calculations shown in the preceding literature. These results can be used to obtain the properties of plasma instabilities in the weakly relativistic regime. (Author) 14 refs

  20. Tracer dispersion - experiment and CFD

    International Nuclear Information System (INIS)

    Zitny, R.

    2004-01-01

    Description of tracer distribution by means of dispersion models is a method successfully used in process engineering for fifty years. Application of dispersion models in reactor engineering for characterization of flows in column apparatus, heat exchangers, etc. is summarized and experimental tracer techniques as well as CFD methods for dispersion coefficients evaluation are discussed. Possible extensions of thermal axial dispersion model (ADM) and a core-wall ADM model suitable for description of tracer dispersion in laminar flows are suggested as well as CFD implementation as 1D finite elements. (author)