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Sample records for particle properties

  1. Review of particle properties

    International Nuclear Information System (INIS)

    Trippe, T.G.; Barbaro-Galtieri, A.; Kelly, R.L.; Rittenberg, A.; Rosenfeld, A.H.; Yost, G.P.; Barash-Schmidt, N.; Bricman, C.; Hemingway, R.J.; Losty, M.J.; Roos, M.; Chaloupka, V.; Armstrong, B.

    1976-01-01

    This review of the properties of leptons, mesons, and baryons is an updating of Review of Particle Properties, Particle Data Group [Phys. Letters 50B, No.1 (1974), and Supplement, Rev. Mod. Phys. 47 (1975) 535]. Data are evaluated, listed, averaged, and summarized in tables. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available

  2. Review of particle properties

    Energy Technology Data Exchange (ETDEWEB)

    Yost, G P; Barnett, R M; Hinchliffe, I; Lynch, G R; Rittenberg, A; Ross, R R; Suzuki, M; Trippe, T G; Wohl, C G; Armstrong, B

    1988-04-14

    This review of the properties of gauge bosons, leptons, mesons, and baryons is an updating of the Review of Particle Properties, Particle Data Group (Phys. Lett. 170B (1986)). Data are evaluated, listed, averaged, and summarized in tables. We continue the more orderly set of particle names implemented in the 1986 edition. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available.

  3. Review of particle properties

    International Nuclear Information System (INIS)

    Montanet, L.; Gieselmann, K. Technical Associate; Barnett, R.M.; Groom, D.E.; Trippe, T.G.; Wohl, C.G.; Armstrong, B. Technical Associate; Wagman, G.S. Technical Associate; Murayama, H.; Stone, J.; Hernandez, J.J.; Porter, F.C.; Morrison, R.J.; Manohar, A.; Aguilar-Benitez, M.; Caso, C.; Lantero, P. Technical Associate; Crawford, R.L.; Roos, M.; Toernqvist, N.A.; Hayes, K.G.; Hoehler, G.

    1994-01-01

    This biennial review summarizes much of Particle Physics. Using data from previous editions, plus 2300 new measurements from 700 papers, we list evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, monopoles, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review

  4. Review of particle properties

    International Nuclear Information System (INIS)

    Bricman, C.; Dionisi, C.; Hemingway, R.J.; Mazzucato, M.; Montanet, L.; Barash-Schmidt, N.; Crawford, R.C.; Roos, M.; Barbaro-Galtieri, A.; Horne, C.P.; Kelly, R.L.; Losty, M.J.; Rittenberg, A.; Trippe, T.G.; Yost, G.P.; Armstrong, B.

    1978-01-01

    This review of the properties of leptons, mesons, and baryons is an updating of Review of Particle Properties, Particle Data Group [Rev. Mod. Phys. 48 (1976) No. 2, Part II; and Supplement, Phys. Lett. 68B (1977) 1]. Data are evaluated, listed, averaged, and summarized in tables. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available. (Auth.)

  5. Review of particle properties

    International Nuclear Information System (INIS)

    Hikasa, K.; Hagiwara, K.; Kawabata, S.; Barnett, R.M.; Groom, D.E.; Trippe, T.G.; Wohl, C.G.; Yost, G.P.; Armstrong, B. Technical Associate; Wagman, G.S. Technical Associate; Stone, J.; Porter, F.C.; Morrison, R.J.; Cutkosky, R.E.; Montanet, L.; Gieselmann, K. Technical Associate; Aguilar-Benitez, M.; Caso, C.; Crawford, R.L.; Roos, M.; Toernqvist, N.A.; Hayes, K.G.; Hoehler, G.; Manley, D.M.

    1992-01-01

    In this Review, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, the top quark, heavy neutrinos, monopoles, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. A booklet is available containing the Summary Tables and abbreviated versions of some other sections of this full Review

  6. Review of particle properties. Particle Data Group

    International Nuclear Information System (INIS)

    1978-04-01

    This review of the properties of leptons, mesons, and baryons is an updating of Review of Particle Properties, Particle Data Group [Rev. Mod. Phys. 48 (1976) No. 2, Part II; and Supplement, Phys. Lett. 68B (1977) 1]. Data are evaluated, listed, averaged, and summarized in tables. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available

  7. Particles in water properties and processes

    CERN Document Server

    Gregory, John

    2005-01-01

    INTRODUCTION Particles in the Aquatic Environment Colloidal Aspects PARTICLE SIZE AND RELATED PROPERTIES Particle Size and Shape Particle Size Distributions Particle Transport Light Scattering and Turbidity Measurement of Particle Size SURFACE CHARGE Origin of Surface Charge The Electrical Double Layer Electrokinetic Phenomena COLLOID INTERACTIONS AND COLLOID STABILITY Colloid Interactions - General Concepts van der Waals Interaction Electrical Double Layer Interaction Combined Interaction - DLVO Theory Non-DLVO Interactions AGGREGATION KINETICS Collision Frequency - Smoluchow

  8. Review of Particle Properties, 1982-1983

    CERN Document Server

    Particle Data Group. Berkeley; Porter, F C; Aguilar-Benítez, M; Montanet, Lucien; Walck, C; Crawford, R L; Kelly, Robert L; Rittenberg, Alan; Trippe, Thomas G; Wohl, Charles G; Yost, George P; Shimada, T; Losty, Michael J; Gopal, Gian P; Hendrick, R E; Shrock, R E; Frosch, R; Roper, L D; Armstrong, Betty

    1982-01-01

    This review of the properties of leptons, mesons, and baryons is an updating of Review of Particle Properties, Particle Data Group [Rev. Mod. Phys. 52 (1980) No. 2, Part II]. Data are evaluated, listed, averaged, and summarized in tables. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available.

  9. Hygroscopic properties of Diesel engine soot particles

    Energy Technology Data Exchange (ETDEWEB)

    Weingartner, E.; Baltensperger, U. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Burtscher, H. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-11-01

    The hygroscopic properties of combustion particles, freshly emitted from a Diesel engine were investigated. It was found that these particles start to grow by water condensation at a relative humidity (RH)>80%. The hygroscopicity of these particles was enhanced when the sulfur content of the fuel was increased or when the particles were artificially aged (i.e. particles were subjected to an ozone or UV pre-treatment). (author) 2 figs., 5 refs.

  10. The Review-of-Particle-Properties system

    International Nuclear Information System (INIS)

    Trippe, T.G.

    1984-01-01

    The Berkeley Particle Data Group is engaged in a major modernization of its primary project, the Review of Particle Properties, a compilation of experimental data on elementary particles. The goal of this modernization is to develop an integrated system for data storage, manipulation, interactive access and publication using modern technqiues for database management, text processing and phototypesetting. The existing system and the plans for modernization are described. The group's other projects and the computer systems used are also discussed. (orig.)

  11. Particle agglomeration and properties of nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Yang Yijun; Oztekin, Alparslan, E-mail: alo2@lehigh.edu; Neti, Sudhakar [Lehigh University, Department of Mechanical Engineering and Mechanics (United States); Mohapatra, Satish [Dynalene Inc. (United States)

    2012-05-15

    The present study demonstrates the importance of actual agglomerated particle size in the nanofluid and its effect on the fluid properties. The current work deals with 5 to 100 nm nanoparticles dispersed in fluids that resulted in 200 to 800 nm agglomerates. Particle size distributions for a range of nanofluids are measured by dynamic light scattering (DLS). Wet scanning electron microscopy method is used to visualize agglomerated particles in the dispersed state and to confirm particle size measurements by DLS. Our results show that a combination of base fluid chemistry and nanoparticle type is very important to create stable nanofluids. Several nanofluids resulted in stable state without any stabilizers, but in the long term had agglomerations of 250 % over a 2 month period. The effects of agglomeration on the thermal and rheological properties are presented for several types of nanoparticle and base fluid chemistries. Despite using nanodiamond particles with high thermal conductivity and a very sensitive laser flash thermal conductivity measurement technique, no anomalous increases of thermal conductivity was measured. The thermal conductivity increases of nanofluid with the particle concentration are as those predicted by Maxwell and Bruggeman models. The level of agglomeration of nanoparticles hardly influenced the thermal conductivity of the nanofluid. The viscosity of nanofluids increased strongly as the concentration of particle is increased; it displays shear thinning and is a strong function of the level of agglomeration. The viscosity increase is significantly above of that predicted by the Einstein model even for very small concentration of nanoparticles.

  12. Particle agglomeration and properties of nanofluids

    International Nuclear Information System (INIS)

    Yang Yijun; Oztekin, Alparslan; Neti, Sudhakar; Mohapatra, Satish

    2012-01-01

    The present study demonstrates the importance of actual agglomerated particle size in the nanofluid and its effect on the fluid properties. The current work deals with 5 to 100 nm nanoparticles dispersed in fluids that resulted in 200 to 800 nm agglomerates. Particle size distributions for a range of nanofluids are measured by dynamic light scattering (DLS). Wet scanning electron microscopy method is used to visualize agglomerated particles in the dispersed state and to confirm particle size measurements by DLS. Our results show that a combination of base fluid chemistry and nanoparticle type is very important to create stable nanofluids. Several nanofluids resulted in stable state without any stabilizers, but in the long term had agglomerations of 250 % over a 2 month period. The effects of agglomeration on the thermal and rheological properties are presented for several types of nanoparticle and base fluid chemistries. Despite using nanodiamond particles with high thermal conductivity and a very sensitive laser flash thermal conductivity measurement technique, no anomalous increases of thermal conductivity was measured. The thermal conductivity increases of nanofluid with the particle concentration are as those predicted by Maxwell and Bruggeman models. The level of agglomeration of nanoparticles hardly influenced the thermal conductivity of the nanofluid. The viscosity of nanofluids increased strongly as the concentration of particle is increased; it displays shear thinning and is a strong function of the level of agglomeration. The viscosity increase is significantly above of that predicted by the Einstein model even for very small concentration of nanoparticles.

  13. Electroweak properties of particle physics. Volume 2

    International Nuclear Information System (INIS)

    Aleksan, R.; Ellis, N.; Falvard, A.; Fayard, L.; Frere, J.M.; Kuehn, J.H.; Le Yaouanc, A.; Roudeau, P.; Wormser, G.

    1991-01-01

    The 23th GIf school was held at Ecole Polytechnique, Palaiseau, France from 16 to 20 September 1991. The subject was large: Electroweak properties of heavy quarks. The second part has been devoted to B physics at hadron machines, search for Top, Charm particle physics and Quarkonium physics

  14. Optical Properties of Airborne Soil Organic Particles

    Energy Technology Data Exchange (ETDEWEB)

    Veghte, Daniel P. [William; China, Swarup [William; Weis, Johannes [Chemical; Department; Kovarik, Libor [William; Gilles, Mary K. [Chemical; Laskin, Alexander [Department

    2017-09-27

    Recently, airborne soil organic particles (ASOP) were reported as a type of solid organic particles emitted after water droplets impacted wet soils. Chemical constituents of ASOP are macromolecules such as polysaccharides, tannins, and lignin (derived from degradation of plants and biological organisms). Optical properties of ASOP were inferred from the quantitative analysis of the electron energy-loss spectra acquired over individual particles in the transmission electron microscope. The optical constants of ASOP are further compared with those measured for laboratory generated particles composed of Suwanee River Fulvic Acid (SRFA) reference material, which was used as a laboratory surrogate of ASOP. The particle chemical compositions were analyzed using energy dispersive x-ray spectroscopy, electron energy-loss spectroscopy, and synchrotron-based scanning transmission x-ray microscopy with near edge x-ray absorption fine structure spectroscopy. ASOP and SRFA exhibit similar carbon composition, but SRFA has minor contributions of S and Na. When ASOP are heated to 350 °C their absorption increases as a result of their pyrolysis and partial volatilization of semi-volatile organic constituents. The retrieved refractive index (RI) at 532 nm of SRFA particles, ASOP, and heated ASOP were 1.22-62 0.07i, 1.29-0.07i, and 1.90-0.38i, respectively. Compared to RISRFA, RIASOP has a higher real part but similar imaginary part. These measurements of ASOP optical constants suggest that they have properties characteristic of atmospheric brown carbon and therefore their potential effects on the radiative forcing of climate need to be assessed in atmospheric models.

  15. Thermodynamic properties of particles with intermediate statistics

    International Nuclear Information System (INIS)

    Joyce, G.S.; Sarkar, S.; Spal/ek, J.; Byczuk, K.

    1996-01-01

    Analytic expressions for the distribution function of an ideal gas of particles (exclusons) which have statistics intermediate between Fermi-Dirac and Bose-Einstein are obtained for all values of the Haldane statistics parameter α element-of[0,1]. The analytic structure of the distribution function is investigated and found to have no singularities in the physical region when the parameter α lies in the range 0 V of the D-dimensional excluson gas. The low-temperature series for the thermodynamic properties illustrate the pseudofermion nature of exclusons. copyright 1996 The American Physical Society

  16. Structure and properties of carbon black particles

    Science.gov (United States)

    Xu, Wei

    Structure and properties of carbon black particles were investigated using atomic force microscopy, gas adsorption, Raman spectroscopy, and X-ray diffraction. Supplementary information was obtained using TEM and neutron scattering. The AFM imaging of carbon black aggregates provided qualitative visual information on their morphology, complementary to that obtained by 3-D modeling based on TEM images. Our studies showed that carbon black aggregates were relatively flat. The surface of all untreated carbon black particles was found to be rough and its fractal dimension was 2.2. Heating reduced the roughness and fractal dimension for all samples heat treated at above 1300 K to 2.0. Once the samples were heat treated rapid cooling did not affect the surface roughness. However, rapid cooling reduced crystallite sizes, and different Raman spectra were obtained for carbon blacks of various history of heat treatment. By analyzing the Raman spectra we determined the crystallite sizes and identified amorphous carbon. The concentration of amorphous carbon depends on hydrogen content. Once hydrogen was liberated at increased temperature, the concentration of amorphous carbon was reduced and crystallites started to grow. Properties of carbon blacks at high pressure were also studied. Hydrostatic pressure did not affect the size of the crystallites in carbon black particles. The pressure induced shift in Raman frequency of the graphitic component was a result of increased intermolecular forces and not smaller crystallites. Two methods of determining the fractal dimension, the FHH model and the yardstick technique based on the BET theory were used in the literature. Our study proved that the FHH model is sensitive to numerous assumptions and leads to wrong conclusions. On the other hand the yardstick method gave correct results, which agreed with the AFM results.

  17. Physical properties of charged particle beams for use in radiotherapy

    International Nuclear Information System (INIS)

    Knapp, E.A.

    1975-01-01

    The physical properties of the possible charged particle beams used for cancer radiotherapy are reviewed. Each property is discussed for all interesting particles (π, p, α, Ne ion) and the differences are emphasized. This is followed by a short discussion of the several beam delivery systems used in particle therapy today, emphasizing the differences in the problems for the several different radiations, particularly the differences between the accelerated particle beams and those of a secondary nature. Dose calculation techniques are described

  18. Elastic Property Simulation of Nano-particle Reinforced Composites

    Directory of Open Access Journals (Sweden)

    He Jiawei

    2016-01-01

    Full Text Available A series of numerical micro-mechanical models for two kinds of particle (cylindrical and discal particle reinforced composites are developed to investigate the effect of microstructural parameters on the elastic properties of composites. The effects of both the degree of particle clustering and particle’s shape on the elastic mechanical properties of composites are investigated. In addition, single particle unit cell approximation is good enough for the analysis of the effect of averaged parameters when only linear elastic response is considered without considering the particle clustering in particle-reinforced composites.

  19. Magnetic Properties of Nanometer-sized Crystalline and Amorphous Particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Bødker, Franz; Hansen, Mikkel Fougt

    1997-01-01

    Amorphous transition metal-metalloid alloy particles can be prepared by chemical preparation techniques. We discuss the preparation of transition metal-boron and iron-carbon particles and their magnetic properties. Nanometer-sized particles of both crystalline and amorphous magnetic materials...... are superparamagnetic at finite temperatures. The temperature dependence of the superparamagnetic relaxation time and the influence of inter-particle interactions is discussed. Finally, some examples of studies of surface magnetization of alpha-Fe particles are presented....

  20. Fatigue properties of particle reinforced aluminium alloys

    International Nuclear Information System (INIS)

    Tabernig, B.J.

    2000-06-01

    In this work the particle reinforced Al-alloys 359 T6 + 20 % SiC and 2124 + 17 % SiC which differ significantly in their production and microstructure are investigated. Standard and in-situ tensile tests show, that in the powder metallurgically produced alloy 2124 reinforcement leads to a higher Young's modulus, yield and ultimate tensile stress where the cast alloy 359 + 20 % SiC exhibit increased stiffness, but low ductility due to cast porosity of some 100 μm. The failure mechanism governed by microstructural parameters is found to play an important role for ductility. The fatigue properties are investigated with specific regard to the influence of the in-service condition (load ratio, temperature, variable amplitude loading) in the foreseen applications in the automobile- and aerospace industry. Standard fatigue tests point out that the endurance limit is improved by reinforcement, but is strongly dependent on the size of given initial defects. The fatigue crack properties are characterised by standard crack growth curves and r(esistance)-curves for the threshold of stress intensity factor range. Both composites exhibit a higher effective threshold than their unreinforced alloys. Furthermore the fatigue resistance described by the R-curve as well as the long crack threshold are improved in the alloy 2124 + 17 % SiC. While in crack growth tests under constant amplitude loading the alloy 2124 + 17 % SiC shows lower crack growth rates than its unreinforced alloy, the opposite case is in the alloy 359 + 20 % SiC at high DK. Periodic overloads lead in the 359 + 20 % SiC to particle fracture at the crack tip and to a steeper increase in the crack growth rate. In the 2124 + 17% SiC the fatigue crack grows predominately in the matrix and a retardation effect due to overloads is observed. In order to describe the fatigue limit of components as a function of initial defect size an analytical concept is developed assuming that the fatigue limit is controlled by the

  1. Properties of supersymmetric particles and processes

    International Nuclear Information System (INIS)

    Barnett, R.M.

    1986-01-01

    The motivations for experimental searches for supersymmetric particles are discussed. The role of R-parity in these searches is described. The production and decay characteristics of each class of supersymmetric particles are investigated in the context of both e+e- and hadron machines. There is a detailed presentation of a sample calculation of a supersymmetric process. Emphasis is given to the signatures for detection of supersymmetric particles and processes. The current limits for supersymmetric particles are given. 125 refs., 50 figs

  2. Properties of microcement mortar with nano particles

    Science.gov (United States)

    Alimeneti, Narasimha Reddy

    Carbon nanotubes (CNT) and Carbon nanofibers (CNF) are one of the toughest and stiffest materials in the world presently with extreme properties yet to be discovered in terms of elastic modulus and tensile strength. Due to the advanced properties of these materials they are being used in almost all fields of science at nanolevel and are being used in construction industry recently for improvement of material properties. Microcement is fine ground cement which as half the particle size of ordinary Portland cement. In this research the behavior of cement mortar of micro cement with the addition of nanoparticles is studied. Due to high aspect ratio and strong van der Waal forces between the particles of CNT and CNF, they agglomerate and form bundles when mixed with water, sonication method is used to mix nanoparticles with few drops of surfactant and super plasticizer. Mechanical properties such as compressive strength and flexural strength with CNT and CNF composites are examined and compared with control samples. 0.1% and 0.05 % of nanoparticles (both CNT and CNF) by the weight of cement are used in this research and 0.8% of super plasticizer by weight of cement was also used along with 0.4, 0.45 and 0.50 water cement ratios for making specimens for compression test. The compressive strength results are not satisfactory as there was no constant increase in strength with all the composites, however strength of few nanocomposites increased by a good percentage. 0.5 water cement ratio cement mortar had compressive strength of 7.15 ksi (49.3 MPa), whereas sample with 0.1% CNT showed 8.38 ksi (57.8 MPa) with 17% increase in strength after 28 days. Same trend was followed by 0.4 water cement ratio as the compressive strength of control sample was 8.89 ksi (61.3 MPa), with 0.05% of CNT strength increased to 10.90 ksi (75.2 MPa) with 23% increase in strength. 0.4 water cement ratio was used for flexural tests including 0.1%, 0.05% of CNT and 0.1%, 0.05% of CNF with 0

  3. Magnetic properties of carbonyl iron particles in magnetorheological fluids

    International Nuclear Information System (INIS)

    Gorodkin, S R; James, R O; Kordonski, W I

    2009-01-01

    Knowledge of the magnetic properties of dispersed magnetic particles is a prerequisite to the design an MR fluid with desired performance. A term specific susceptibility is introduced for characterization of particle susceptibility. The study was performed with the Bartington MS2B magnetic susceptibility system on small samples volume. Specific magnetic susceptibility of iron particles was found to be a linear function of median particle size. Structural change in the fluid, including particle organization, led to susceptibility drift and may affect fluid performance. It was shown that susceptibility data can be used for evaluation of the concentration of carbonyl iron particles in MR fluids.

  4. Redox properties of small semiconductor particles

    International Nuclear Information System (INIS)

    Liver, N.; Nitzan, A.

    1992-01-01

    The size dependence of electrical and thermodynamic quantities of intermediate-sized semiconductor particles in an electrolyte solution with a given redox pair are studied. The equilibrium constant for this system is then derived based on the relationship of the electrolytic redox components to the size, charges, and concentration of the semiconductor particles. 25 refs., 9 figs., 1 tab

  5. Analytic properties of many-particle amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Medvedev, B V; Pavlov, V P; Polivanov, M K; Sukhanov, A D [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Teoreticheskoj i Ehksperimental' noj Fiziki; AN SSSR, Moscow. Matematicheskij Inst.)

    1982-08-01

    In the framework of N. N. Bogolyubov axiomatic approach the complete proof of the existence of an analytic function the boundary values of which are the amplitudes of any channel of n-particle process is given. The one-particle structure of this function is described.

  6. Review of particle properties. 25th anniversary edition

    International Nuclear Information System (INIS)

    1982-04-01

    This review is a reprint of Physics Letters, Vol. IIIB, April 22, 1982, and is an updating through December 1981 of our previous review of particle properties [Particle Data Group (1980)]. As in previous editions we have attempted to make the text as complete and self-contained as possible. The results of our compilation are presented in two sections, the Tables of Particle Properties and the Data Card Listings. The Tables summarize the properties of only those particles whose existence is in our judgment experimentally well founded and which have a high probability of standing the test of time. The Data Card Listings give up-to-date information, with references, on all reported particles, whether considered well established or not. The Listings also contain mini-reviews on questions of interest. As in previous editions, we include a section of miscellaneous tables, figures, and formulae. These are aimed at the practicing high energy physics experimentalist

  7. Effective modification of particle surface properties using ultrasonic water mist

    DEFF Research Database (Denmark)

    Genina, Natalja; Räikkönen, Heikki; Heinämäki, Jyrki

    2009-01-01

    The goal of the present study was to design a new technique to modify particle surface properties and, through that, to improve flowability of poorly flowing drug thiamine hydrochloride and pharmaceutical sugar lactose monohydrate of two different grades. The powdered particles were supplied...... properties. It was found that rapid exposition of pharmaceutical materials by water mist resulted in the improvement of powder technical properties. The evident changes in flowability of coarser lactose were obviously due to smoothing of particle surface and decreasing in the level of fines with very slight...... increment in particle size. The changes in thiamine powder flow were mainly due to narrowing in particle size distribution where the tendency for better flow of finer lactose was related to surface and size modifications. The aqueous mist application did not cause any alteration of the crystal structures...

  8. Review of particle properties 1975: Supplement to 1974 edition

    CERN Document Server

    Particle Data Group. Berkeley; Bricman, Claude; Barbaro-Galtieri, Angela; Chew, Denyse M; Kelly, Robert L; Lasinski, Thomas A; Rittenberg, Alan; Rosenfeld, Arthur Hinton; Trippe, Thomas G; Uchiyama, Fumiyo; Yost, George P; Barash-Schmidt, Naomi; Roos, Matts

    1975-01-01

    This supplement to the 1974 edition of "Review of Particle Properties," Particle Data Group Phys. Lett. 50B, (1974), contains an announcement concerning the postponement of the usual Review, a list of Errata, and a tabulation of the experimental results on the newly discovered mesons.

  9. The properties of charmonium and charm particles

    International Nuclear Information System (INIS)

    Schopper, H.

    1977-12-01

    An impressive amount of data has been accumulated over the past three years which support strongly the idea that elementary particles are composed of four quarks instead of three. All the predictions based on the existence of the fourth, the charm quark, have in principal been born out by experiments and from detailed investigations very interesting results could be obtained for the strong and the weak interaction. Most of these results have been obtained with electron-positron storage rings, and only these will be discussed in this report. Additional data from hadronic or neutrino interactions are in general agreement with the e + e - data and will not be discussed here. This series of lectures will be entirely devoted to a discussion of mesons, i.e. quark-antiquark systems. Although some indications have been found for the existence of charmed baryons, these data are still rather scanty. In the last chapter we shall also discuss the upsilon particle. (orig.) [de

  10. Relaxation property of the fractional Brownian particle

    International Nuclear Information System (INIS)

    Wang Litan; Lung, C.W.

    1988-08-01

    Dynamic susceptibility of a diffusion system associated with the fractional Brownian motion (fBm) was examined for the fractal property of the Non-Debye relaxation process. The comparisons between fBm and other approaches were made. Anomalous diffusion and the Non-Debye relaxation processes were discussed with this approach. (author). 8 refs, 1 fig

  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. Properties of magnetic nano-particles

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1997-01-01

    The intrinsic thermodynamic magnetic properties of clusters are discussed using spin wave theory for a Heisenberg model, with a fixed magnitude of the spins S-i = S and site independent nearest neighbor exchange interaction. The consequences of the more realistic Hubbard model is considered...... in which we allow for a magnetization profile at T = 0 and a structural relaxation, which in turn will give rise to a site dependent exchange interaction. Et is concluded that correlation effects among the electrons play a very important role in small clusters, albeit not modifying the thermodynamic...... properties drastically. The finite cluster size gives foremost rise to a discrete excitation spectrum with a large energy gap to the ground state. The relaxation of the magnetization during the reversal of the external magnetic field is discussed. A first step towards a quantitative understanding...

  13. Waste Slurry Particle Properties for Use in Slurry Flow Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Jewett, J. R.; Conrads, T. J.; Julyk, L. J.; Reynolds, D. A.; Jensen, L.; Kirch, N. W.; Estey, S. D.; Bechtold, D. B.; Callaway III, W. S.; Cooke, G. A.; Herting, D. L.; Person, J. C.; Duncan, J. B.; Onishi, Y.; Tingey, J. M.

    2003-02-26

    Hanford's tank farm piping system must be substantially modified to deliver high-level wastes from the underground storage tanks to the Waste Treatment Plant now under construction. Improved knowledge of the physical properties of the solids was required to support the design of the modified system. To provide this additional knowledge, particle size distributions for composite samples from seven high-level waste feed tanks were measured using two different laser lightscattering particle size analyzers. These measurements were made under a variety of instrumental conditions, including various flow rates through the sample loop, various stirring rates in the sample reservoir, and before and after subjecting the particles to ultrasonic energy. A mean value over all the tanks of 4.2 {micro}m was obtained for the volume-based median particle size. Additional particle size information was obtained from sieving tests, settling tests and microscopic observations.

  14. Diffusion properties of active particles with directional reversal

    International Nuclear Information System (INIS)

    Großmann, R; Bär, M; Peruani, F

    2016-01-01

    The diffusion properties of self-propelled particles which move at constant speed and, in addition, reverse their direction of motion repeatedly are investigated. The internal dynamics of particles triggering these reversal processes is modeled by a stochastic clock. The velocity correlation function as well as the mean squared displacement is investigated and, furthermore, a general expression for the diffusion coefficient for self-propelled particles with directional reversal is derived. Our analysis reveals the existence of an optimal, finite rotational noise amplitude which maximizes the diffusion coefficient. We comment on the relevance of these results with regard to biological systems and suggest further experiments in this context. (paper)

  15. Properties of submicron particles in Atmospheric Brown Clouds

    Science.gov (United States)

    Adushkin, V. V.; Chen, B. B.; Dubovskoi, A. N.; Friedrich, F.; Pernik, L. M.; Popel, S. I.; Weidler, P. G.

    2010-05-01

    The Atmospheric Brown Clouds (ABC) is an important problem of this century. Investigations of last years and satellite data show that the ABC (or brown gas, smog, fog) cover extensive territories including the whole continents and oceans. The brown gas consists of a mixture of particles of anthropogenic sulfates, nitrates, organic origin, black carbon, dust, ashes, and also natural aerosols such as sea salt and mineral dust. The brown color is a result of absorption and scattering of solar radiation by the anthropogenic black carbon, ashes, the particles of salt dust, and nitrogen dioxide. The investigation of the ABC is a fundamental problem for prevention of degradation of the environment. At present in the CIS in-situ investigations of the ABC are carried out on Lidar Station Teplokluchenka (Kyrgyz Republic). Here, we present the results of experimental investigation of submicron (nanoscale) particles originating from the ABC and the properties of the particles. Samples of dust precipitating from the ABC were obtained at the area of Lidar Station Teplokluchenka as well as scientific station of the Russian Academy of Sciences near Bishkek. The data for determination of the grain composition were obtained with the aid of the scanning electron microscopes JEOL 6460 LV and Philips XL 30 FEG. Analysis of the properties of the particles was performed by means of the X-ray diffraction using diffractometer Siemens D5000. The images of the grains were mapped. The investigation allows us to get (after the image processing) the grain composition within the dust particle size range of 60 nm to 700 μm. Distributions of nano- and microscale particles in sizes were constructed using Rozin-Rammler coordinates. Analysis of the distributions shows that the ABC contain submicron (nanoscale) particles; 2) at higher altitudes the concentration of the submicron (nanoscale) particles in the ABC is higher than at lower altitudes. The chemical compositions of the particles are shown to

  16. r-particle irreducible kernels, asymptotic completeness and analyticity properties of several particle collision amplitudes

    International Nuclear Information System (INIS)

    Bros, J.

    1984-01-01

    An account is given of the present status of many-particle structure analysis in the general framework of massive quantum field theory. Two main questions are discussed, namely: i) the equivalence between the asymptotic completeness of a field and the r-particle irreducibility of associated Bether-Salpeter type kernels; ii) the derivation of extended analyticity properties of the Green functions and multiparticle collision amplitudes around the corresponding physical regions. Substantial results concerning the 3→3 particle processes are described. An analogous multiparticle version of these results yields a partial understanding of the general case

  17. Controlling the scattering properties of thin, particle-doped coatings

    Science.gov (United States)

    Rogers, William; Corbett, Madeleine; Manoharan, Vinothan

    2013-03-01

    Coatings and thin films of small particles suspended in a matrix possess optical properties that are important in several industries from cosmetics and paints to polymer composites. Many of the most interesting applications require coatings that produce several bulk effects simultaneously, but it is often difficult to rationally formulate materials with these desired optical properties. Here, we focus on the specific challenge of designing a thin colloidal film that maximizes both diffuse and total hemispherical transmission. We demonstrate that these bulk optical properties follow a simple scaling with two microscopic length scales: the scattering and transport mean free paths. Using these length scales and Mie scattering calculations, we generate basic design rules that relate scattering at the single particle level to the film's bulk optical properties. These ideas will be useful in the rational design of future optically active coatings.

  18. Assembling and properties of the polymer-particle nanostructured materials

    Science.gov (United States)

    Sheparovych, Roman

    Complementary properties of the soft and hard matter explain its common encounter in many natural and manmade applications. A combination of flexible organic macromolecules and hard mineral clusters results in new materials far advantageous than its constituents alone. In this work we study assembling of colloidal nanocrystals and polymers into complex nanostructures. Magnetism, surface wettability and adhesion comprise properties of interest for the obtained nanocomposites. Applying a magnetic field induces a reversible 1D ordering of the magnetically susceptible particles. This property was employed in the fabrication of the permanent chains of magnetite nanocrystals (d=15nm). In the assembling process the aligned particles were bound together using polyelectrolyte macromolecules. The basics of the binding process involved an electrostatic interaction between the positively charged polyelectrolyte and the negative surface of the particles (aqueous environment). Adsorption of the polymer molecules onto several adjacent particles in the aligned 1D aggregate results in the formation of the permanent particulate chains. Positive charges of the adsorbed polyelectrolyte molecules stabilize the dispersion of the obtained nanostructures in water. Magnetization measurements revealed that superparamagnetic nanoparticles, being assembled into 1D ordered structures, attain magnetic coercivity. This effect originates from the magnetostatic interaction between the neighboring magnetite nanocrystals. The preferable dipole alignment of the assembled nanoparticles is directed along the chain axis. Another system studied in this project includes polymer-particle responsive surface coatings. Tethered polymer chains and particles bearing different functionalities change surface properties upon restructuring of the composite layer. When the environment favors polymer swelling (good solvent), the polymer chains segregate to the surface and cover the particles. In the opposite case

  19. Electromagnetic properties of off-shell particles and gauge invariance

    NARCIS (Netherlands)

    Nagorny, S. I.; Dieperink, A. E. L.

    1998-01-01

    Abstract: Electromagnetic properties of off-shell particles are discussed on the basis of a purely electromagnetic reaction: virtual Compton scattering off a proton. It is shown that the definition of off-shell electromagnetic form factors is not gauge invariant and that these cannot be investigated

  20. Modulation of Cyclodextrin Particle Amphiphilic Properties to Stabilize Pickering Emulsion.

    Science.gov (United States)

    Xi, Yongkang; Luo, Zhigang; Lu, Xuanxuan; Peng, Xichun

    2018-01-10

    Cyclodextrins have been proven to form complexes with linear oil molecules and stabilize emulsions. Amphiphilic properties of cyclodextrin particles were modulated through esterification reaction between β-cyclodextrin (β-CD) and octadecenyl succinic anhydride (ODSA) under alkaline conditions. ODS-β-CD particles with degree of substitution (DS) of 0.003, 0.011, and 0.019 were obtained. The introduced hydrophobic long chain that was linked within β-CD cavity led to the change of ODS-β-CD in terms of morphological structure, surface charge density, size, and contact angle, upon which the properties and stability of the emulsions stabilized by ODS-β-CD were highly dependent. The average diameter of ODS-β-CD particles ranged from 449 to 1484 nm. With the DS increased from 0.003 to 0.019, the contact angle and absolute zeta potential value of these ODS-β-CD particles improved from 25.7° to 47.3° and 48.1 to 62.8 mV, respectively. The cage structure of β-CD crystals was transformed to channel structure, then further to amorphous structure after introduction of the octadecenyl succinylation chain. ODS-β-CD particles exhibited higher emulsifying ability compared to β-CD. The resulting Pickering emulsions formed by ODS-β-CD particles were more stable during storage. This study investigates the ability of these ODS-β-CD particles to stabilize oil-in-water emulsions with respect to their amphiphilic character and structural properties.

  1. Aerodynamic properties of six organo-mineral fertiliser particles

    Directory of Open Access Journals (Sweden)

    Marcello Biocca

    2013-09-01

    Full Text Available Agricultural fertilisers are generally applied by means of centrifugal disk spreaders. The machinery, the working conditions and the physical characteristics of fertilizers (including the aerodynamic characteristics of particles may affect the behaviour of particles after the discarding from the spreader. We investigated the aerodynamic properties of organo-mineral fertilisers (a class of slow release fertilisers that are less investigated since they are relatively new in the market using a vertical wind tunnel similar to an elutriator. In the same time, the morphological characteristics of individual fertilizer particles were measured by means of an image analysis procedure. In the study we compare six different fertilisers and we discuss the suitability of the employed methods. The results provide the terminal velocity – Vt – (the velocity value that overcome the gravity force of the particles of the particles, ranging from 8.60 to 9.55 m s-1, and the relationships between Vt and some physical properties (mass, shape, dimensions of the fertilizers. Moreover, the results of field distribution trials show the behaviour of the tested fertilizers during practical use. Such data can contribute to enhance the quality of application of these products in field.

  2. Properties of amorphous FeCoB alloy particles (abstract)

    DEFF Research Database (Denmark)

    Charles, S. W.; Wells, S.; Meagher, A.

    1988-01-01

    -ray diffraction. Magnetic measurements of the saturation magnetization, coercivity, and remanence of the particles have been measured. The transition from the amorphous-to-crystalline state has been studied using differential scanning calorimetry (DSC) and thermomagnetometry up to a temperature of 450 °C (see Fig......Amorphous and crystalline alloy particles (0.05–0.5 nm) of FexCoyBz in which the ratio x:y ranges from 0 to 1 have been prepared by the borohydride reduction of iron and cobalt salts in aqueous solution. The structure of the particles has been studied using Mössbauer spectroscopy and x....... 1). It has been shown that the fraction of boron in the alloys (10–35 at. %) is dependent upon the rate of addition of salts to borohydride and the concentration of cobalt present; this in turn influences the crystallinity and magnetic properties . Journal of Applied Physics is copyrighted...

  3. Mechanical properties of epoxy/coconut shell filler particle composites

    International Nuclear Information System (INIS)

    Sapuan, S.M.; Harimi, M.; Maleque, M.A.

    2003-01-01

    This paper presents the tensile and flexural properties of composites made from coconut shell filler particles and epoxy resin. The tensile and flexural tests of composites based on coconut shell filler particles at three different filler contents viz., 5%, 0% and 15%were carried out using universal tensile testing machine according to ASTM D 3039/D M-95a and ASTM D790-90 tensile respectively and their results were presented. Experimental results showed that tensile and flexural properties of the composites increased with the increase of the filler particle content. The composite materials demonstrate somewhat linear behavior and sharp structure for tensile and slight nonlinear behavior and sharp fracture of flexural testing. The relation between stress and percentage of filler for tensile and flexural tests were found to b linear with correlation factors of 0.9929 and 0.9973 respectively. Concerning the relation between the modulus and percentage of filler for tensile and flexural tests, it was found to be a quadratic relation with the same correlation factor approximated to 1. The same behavior was observed for the strain versus percentage of filler tensile and flexural tests, with the same correlation factor. (author)

  4. Quantum algebras in phenomenological description of particle properties

    International Nuclear Information System (INIS)

    Gavrilik, A.M.

    2001-01-01

    Quantum and q-deformed algebras find their application not only in mathematical physics and field theoretical context, but also in phenomenology of particle properties. We describe (i) the use of quantum algebras U q (su n ) corresponding to Lie algebras of the groups SU n , taken for flavor symmetries of hadrons, in deriving new high-accuracy hadron mass sum rules, and (ii) the use of (multimode) q-oscillator algebras along with q-Bose gas picture in modelling the properties of the intercept λ of two-pion (two-kaon) correlations in heavy-ion collisions, as λ shows sizable observed deviation from the expected Bose-Einstein type behavior. The deformation parameter q is in case (i) argued and in case (ii) conjectured to be connected with the Cabibbo angle θ c

  5. Measurement of the particle production properties in ATLAS

    CERN Document Server

    Bruni, Alessia; The ATLAS collaboration

    2017-01-01

    Measurements of the particle production properties with the ATLAS detector A correct modelling of the underlying event in proton-proton collisions is important for the proper simulation of kinematic distributions of high-energy collisions. The ATLAS collaboration extended previous studies at 7 TeV with a leading track or jet or Z boson by a new study at 13 TeV, measuring the number and transverse-momentum sum of charged particles as a function of pseudorapidity and azimuthal angle in dependence of the reconstructed leading track. These measurements are sensitive to the underlying-event as well as the onset of hard emissions. The results are compared to predictions of several MC generators. A similar comparison between measurements and MC generator predictions will be shown for the strange meson content in topquark pair events. Studies of particle correlations in high-energy collisions can provide valuable insights into the detailed understanding of the space-time geometry of the hadronization region. The ATLA...

  6. Influence of Particle Size on Properties of Expanded Graphite

    Directory of Open Access Journals (Sweden)

    Kurajica, S

    2010-02-01

    Full Text Available Expanded graphite has been applied widely in thermal insulation, adsorption, vibration damping, gasketing, electromagnetic interference shielding etc. It is made by intercalation of natural flake graphite followed by thermal expansion. Intercalation is a process whereby an intercalant material is inserted between the graphene layers of a graphite crystal. Exfoliation, a huge unidirectional expansion of the starting intercalated flakes, occurs when the graphene layers are forced apart by the sudden decomposition and vaporization of the intercalated species by thermal shock. Along with production methodologies, such as the intercalation process and heat treatment, the raw material characteristics, especially particle size, strongly influence the properties of the final product.This report evaluates the influence of the particle size of the raw material on the intercalation and expansion processes and consequently the properties of the exfoliated graphite. Natural crystalline flake graphite with wide particle diameter distribution (between dp = 80 and 425 µm was divided into four size-range portions by sieving. Graphite was intercalated via perchloric acid, glacial acetic acid and potassium dichromate oxidation and intercalation procedure. 5.0 g of graphite, 7.0 g of perchloric acid, 4.0 g of glacial acetic acid and 2.0 g of potassium dichromate were placed in glass reactor. The mixture was stirred with n = 200 min–1 at temperature of 45 °C during 60 min. Then it was filtered and washed with distilled water until pH~6 and dried at 60 °C during 24 h. Expansion was accomplished by thermal shock at 1000 °C for 1 min. The prepared samples were characterized by means of exfoliation volume measurements, simultaneous differential thermal analysis and thermo-gravimetry (DTA/TGA, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, BET measurements and scanning electron microscopy (SEM.X-ray diffraction indicated a change of distance

  7. Statistical properties of the normalized ice particle size distribution

    Science.gov (United States)

    Delanoë, Julien; Protat, Alain; Testud, Jacques; Bouniol, Dominique; Heymsfield, A. J.; Bansemer, A.; Brown, P. R. A.; Forbes, R. M.

    2005-05-01

    Testud et al. (2001) have recently developed a formalism, known as the "normalized particle size distribution (PSD)", which consists in scaling the diameter and concentration axes in such a way that the normalized PSDs are independent of water content and mean volume-weighted diameter. In this paper we investigate the statistical properties of the normalized PSD for the particular case of ice clouds, which are known to play a crucial role in the Earth's radiation balance. To do so, an extensive database of airborne in situ microphysical measurements has been constructed. A remarkable stability in shape of the normalized PSD is obtained. The impact of using a single analytical shape to represent all PSDs in the database is estimated through an error analysis on the instrumental (radar reflectivity and attenuation) and cloud (ice water content, effective radius, terminal fall velocity of ice crystals, visible extinction) properties. This resulted in a roughly unbiased estimate of the instrumental and cloud parameters, with small standard deviations ranging from 5 to 12%. This error is found to be roughly independent of the temperature range. This stability in shape and its single analytical approximation implies that two parameters are now sufficient to describe any normalized PSD in ice clouds: the intercept parameter N*0 and the mean volume-weighted diameter Dm. Statistical relationships (parameterizations) between N*0 and Dm have then been evaluated in order to reduce again the number of unknowns. It has been shown that a parameterization of N*0 and Dm by temperature could not be envisaged to retrieve the cloud parameters. Nevertheless, Dm-T and mean maximum dimension diameter -T parameterizations have been derived and compared to the parameterization of Kristjánsson et al. (2000) currently used to characterize particle size in climate models. The new parameterization generally produces larger particle sizes at any temperature than the Kristjánsson et al. (2000

  8. Microphysical Properties of Single Secondary Organic Aerosol (SOA) Particles

    Science.gov (United States)

    Rovelli, Grazia; Song, Young-Chul; Pereira, Kelly; Hamilton, Jacqueline; Topping, David; Reid, Jonathan

    2017-04-01

    Secondary Organic Aerosols (SOA) deriving from the oxidation of volatile organic compounds (VOCs) can account for a substantial fraction of the overall atmospheric aerosol mass.[1] Therefore, the investigation of SOA microphysical properties is crucial to better comprehend their role in the atmospheric processes they are involved in. This works describes a single particle approach to accurately characterise the hygroscopic response, the optical properties and the gas-particle partitioning kinetics of water and semivolatile components for laboratory generated SOA. SOA was generated from the oxidation of different VOCs precursors (e.g. α-pinene, toluene) in a photo-chemical flow reactor, which consists of a temperature and relative humidity controlled 300 L polyvinyl fluoride bag. Known VOC, NOx and ozone concentrations are introduced in the chamber and UV irradiation is performed by means of a Hg pen-ray. SOA samples were collected with an electrical low pressure impactor, wrapped in aluminium foil and kept refrigerated at -20°C. SOA samples were extracted in a 1:1 water/methanol mixture. Single charged SOA particles were generated from the obtained solution using a microdispenser and confined within an electrodynamic balance (EDB), where they sit in a T (250-320 K) and RH (0-95%) controlled nitrogen flow. Suspended droplets are irradiated with a 532 nm laser and the evolving angularly resolved scattered light is used to keep track of changes in droplet size. One of the key features of this experimental approach is that very little SOA solution is required because of the small volumes needed to load the dispensers (evaporation kinetics experiments (CK-EDB) of suspended probe and sample droplets.[2] The variation of the refractive index of SOA droplets following to water or SVOCs evaporative loss was measured as a function of water activity by fitting the collected light scattering patterns with a generated Mie-Theory library of phase functions.[3] Long trapping

  9. Quantifying the motion of magnetic particles in excised tissue: Effect of particle properties and applied magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, Sandip, E-mail: sandip.d.kulkarni@gmail.com [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Ramaswamy, Bharath; Horton, Emily; Gangapuram, Sruthi [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Nacev, Alek [Weinberg Medical Physics, LLC (United States); Depireux, Didier [The Institute for Systems Research, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States); Shimoji, Mika [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States); Shapiro, Benjamin [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); The Institute for Systems Research, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States)

    2015-11-01

    This article presents a method to investigate how magnetic particle characteristics affect their motion inside tissues under the influence of an applied magnetic field. Particles are placed on top of freshly excised tissue samples, a calibrated magnetic field is applied by a magnet underneath each tissue sample, and we image and quantify particle penetration depth by quantitative metrics to assess how particle sizes, their surface coatings, and tissue resistance affect particle motion. Using this method, we tested available fluorescent particles from Chemicell of four sizes (100 nm, 300 nm, 500 nm, and 1 μm diameter) with four different coatings (starch, chitosan, lipid, and PEG/P) and quantified their motion through freshly excised rat liver, kidney, and brain tissues. In broad terms, we found that the applied magnetic field moved chitosan particles most effectively through all three tissue types (as compared to starch, lipid, and PEG/P coated particles). However, the relationship between particle properties and their resulting motion was found to be complex. Hence, it will likely require substantial further study to elucidate the nuances of transport mechanisms and to select and engineer optimal particle properties to enable the most effective transport through various tissue types under applied magnetic fields.

  10. Static and dynamic properties of smoothed dissipative particle dynamics

    Science.gov (United States)

    Alizadehrad, Davod; Fedosov, Dmitry A.

    2018-03-01

    In this paper, static and dynamic properties of the smoothed dissipative particle dynamics (SDPD) method are investigated. We study the effect of method parameters on SDPD fluid properties, such as structure, speed of sound, and transport coefficients, and show that a proper choice of parameters leads to a well-behaved and accurate fluid model. In particular, the speed of sound, the radial distribution function (RDF), shear-thinning of viscosity, the mean-squared displacement (〈R2 〉 ∝ t), and the Schmidt number (Sc ∼ O (103) - O (104)) can be controlled, such that the model exhibits a fluid-like behavior for a wide range of temperatures in simulations. Furthermore, in addition to the consideration of fluid density variations for fluid compressibility, a more challenging test of incompressibility is performed by considering the Poisson ratio and divergence of velocity field in an elongational flow. Finally, as an example of complex-fluid flow, we present the applicability and validity of the SDPD method with an appropriate choice of parameters for the simulation of cellular blood flow in irregular geometries. In conclusion, the results demonstrate that the SDPD method is able to approximate well a nearly incompressible fluid behavior, which includes hydrodynamic interactions and consistent thermal fluctuations, thereby providing, a powerful approach for simulations of complex mesoscopic systems.

  11. Viscous properties of ferrofluids containing both micrometer-size magnetic particles and fine needle-like particles

    Energy Technology Data Exchange (ETDEWEB)

    Ido, Yasushi, E-mail: ido.yasushi@nitech.ac.jp [Department of Electric and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya (Japan); Nishida, Hitoshi [Department of Electrical and Control Systems Engineering, National Institute of Technology, Toyama College, 13 Hongo-cho, Toyama (Japan); Iwamoto, Yuhiro [Department of Electric and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya (Japan); Yokoyama, Hiroki [KYB Corporation, 2-4-1 Hamamatsu-cho, Minato-ku, Tokyo (Japan)

    2017-06-01

    Ferrofluids containing both micrometer-size spherical magnetic particles and nanometer-size needle-like nonmagnetic hematite particles were newly produced. Average length of long axis of the needle-like nonmagnetic particles was 194 nm and the aspect ratio was 8.3. Shear stress and viscosity were measured using the rheometer with the additional equipment for viscosity measurements in the presence of magnetic field. When the total volume fraction of particles in the fluid is constant (0.30), there is the specific mixing ratio of the particles to increase viscosity of the fluid drastically in the absence of magnetic field due to the percolation phenomenon. The fluid of the specific mixing ratio shows solid-like behavior even in the absence of magnetic field. Mixing the needle-like nonmagnetic particles causes strong yield stress and strong viscous force in the presence of magnetic field. - Highlights: • Viscous properties of new magnetic functional fluids were studied experimentally. • The new fluids contain spherical magnetic particles and needle-like particles. • Percolation occurs in the fluid of specific mixing ratio of particles without field. • The fluid of the specific mixing ratio behaves like solid without field. • Mixing needle-like particles causes strong yield stress of the fluid in the field.

  12. TRISO coated fuel particles with enhanced SiC properties

    International Nuclear Information System (INIS)

    Lopez-Honorato, E.; Tan, J.; Meadows, P.J.; Marsh, G.; Xiao, P.

    2009-01-01

    The silicon carbide (SiC) layer used for the formation of TRISO coated fuel particles is normally produced at 1500-1650 deg. C via fluidized bed chemical vapor deposition from methyltrichlorosilane in a hydrogen environment. In this work, we show the deposition of SiC coatings with uniform grain size throughout the coating thickness, as opposed to standard coatings which have larger grain sizes in the outer sections of the coating. Furthermore, the use of argon as the fluidizing gas and propylene as a carbon precursor, in addition to hydrogen and methyltrichlorosilane, allowed the deposition of stoichiometric SiC coatings with refined microstructure at 1400 and 1300 deg. C. The deposition of SiC at lower deposition temperatures was also advantageous since the reduced heat treatment was not detrimental to the properties of the inner pyrolytic carbon which generally occurs when SiC is deposited at 1500 deg. C. The use of a chemical vapor deposition coater with four spouts allowed the deposition of uniform and spherical coatings.

  13. Snow particles extracted from X-ray computed microtomography imagery and their single-scattering properties

    Science.gov (United States)

    Ishimoto, Hiroshi; Adachi, Satoru; Yamaguchi, Satoru; Tanikawa, Tomonori; Aoki, Teruo; Masuda, Kazuhiko

    2018-04-01

    Sizes and shapes of snow particles were determined from X-ray computed microtomography (micro-CT) images, and their single-scattering properties were calculated at visible and near-infrared wavelengths using a Geometrical Optics Method (GOM). We analyzed seven snow samples including fresh and aged artificial snow and natural snow obtained from field samples. Individual snow particles were numerically extracted, and the shape of each snow particle was defined by applying a rendering method. The size distribution and specific surface area distribution were estimated from the geometrical properties of the snow particles, and an effective particle radius was derived for each snow sample. The GOM calculations at wavelengths of 0.532 and 1.242 μm revealed that the realistic snow particles had similar scattering phase functions as those of previously modeled irregular shaped particles. Furthermore, distinct dendritic particles had a characteristic scattering phase function and asymmetry factor. The single-scattering properties of particles of effective radius reff were compared with the size-averaged single-scattering properties. We found that the particles of reff could be used as representative particles for calculating the average single-scattering properties of the snow. Furthermore, the single-scattering properties of the micro-CT particles were compared to those of particle shape models using our current snow retrieval algorithm. For the single-scattering phase function, the results of the micro-CT particles were consistent with those of a conceptual two-shape model. However, the particle size dependence differed for the single-scattering albedo and asymmetry factor.

  14. Absorption and scattering properties of arbitrarily shaped particles in the Rayleigh domain

    International Nuclear Information System (INIS)

    Min, M.; Hovenier, J.W.; Dominik, C.; Koter, A. de; Yurkin, M.A.

    2006-01-01

    We provide a theoretical foundation for the statistical approach for computing the absorption properties of particles in the Rayleigh domain. We present a general method based on the discrete dipole approximation to compute the absorption and scattering properties of particles in the Rayleigh domain. The method allows to separate the geometrical aspects of a particle from its material properties. Doing the computation of the optical properties of a particle once, provides them for any set of refractive indices, wavelengths and orientations. This allows for fast computations of e.g. absorption spectra of arbitrarily shaped particles. Other practical applications of the method are in the interpretation of atmospheric and radar measurements as well as computations of the scattering matrix of small particles as a function of the scattering angle. In the statistical approach, the optical properties of irregularly shaped particles are represented by the average properties of an ensemble of particles with simple shapes. We show that the absorption cross section of an ensemble of arbitrarily shaped particles with arbitrary orientations can always be uniquely represented by the average absorption cross section of an ensemble of spheroidal particles with the same composition and fixed orientation. This proves for the first time that the statistical approach is generally viable in the Rayleigh domain

  15. Effect of particle-size dynamics on properties of dense spongy-particle systems: Approach towards equilibrium

    Science.gov (United States)

    Zakhari, Monica E. A.; Anderson, Patrick D.; Hütter, Markus

    2017-07-01

    Open-porous deformable particles, often envisaged as sponges, are ubiquitous in biological and industrial systems (e.g., casein micelles in dairy products and microgels in cosmetics). The rich behavior of these suspensions is owing to the elasticity of the supporting network of the particle, and the viscosity of permeating solvent. Therefore, the rate-dependent size change of these particles depends on their structure, i.e., the permeability. This work aims at investigating the effect of the particle-size dynamics and the underlying particle structure, i.e., the particle permeability, on the transient and long-time behavior of suspensions of spongy particles in the absence of applied deformation, using the dynamic two-scale model developed by Hütter et al. [Farad. Discuss. 158, 407 (2012), 10.1039/c2fd20025b]. In the high-density limit, the transient behavior is found to be accelerated by the particle-size dynamics, even at average size changes as small as 1 % . The accelerated dynamics is evidenced by (i) the higher short-time diffusion coefficient as compared to elastic-particle systems and (ii) the accelerated formation of the stable fcc crystal structure. Furthermore, after long times, the particle-size dynamics of spongy particles is shown to result in lower stationary values of the energy and normal stresses as compared to elastic-particle systems. This dependence of the long-time behavior of these systems on the permeability, that essentially is a transport coefficient and hence must not affect the equilibrium properties, confirms that full equilibration has not been reached.

  16. Influence of the precursors on the properties of alumina supported rhodium particles

    International Nuclear Information System (INIS)

    Coq, B.; Figueras, F.; Tazi, T.

    1989-01-01

    The effect of chlorine on the properties of Rh particles supported on alumina was studied using the hydroconversion of alkanes as a molecular probe. Chloride ions on the alumina have little influence on the Rh particles. Chlorine adsorbed on the Rh particles decreases the chemisorption capacity and increases the metal-support interaction, which results in modifications of their catalytic properties. Depending on the alkane processed, specific activity can be depressed up to four orders of magnitude. (orig.)

  17. Statistical properties of the ice particle distribution in stratiform clouds

    Science.gov (United States)

    Delanoe, J.; Tinel, C.; Testud, J.

    2003-04-01

    This paper presents an extensive analysis of several microphysical data bases CEPEX, EUCREX, CLARE and CARL to determine statistical properties of the Particle Size Distribution (PSD). The data base covers different type of stratiform clouds : tropical cirrus (CEPEX), mid-latitude cirrus (EUCREX) and mid-latitude cirrus and stratus (CARL,CLARE) The approach for analysis uses the concept of normalisation of the PSD developed by Testud et al. (2001). The normalization aims at isolating three independent characteristics of the PSD : its "intrinsic" shape, the "average size" of the spectrum and the ice water content IWC, "average size" is meant the mean mass weighted diameter. It is shown that concentration should be normalized by N_0^* proportional to IWC/D_m^4. The "intrinsic" shape is defined as F(Deq/D_m)=N(Deq)/N_0^* where Deq is the equivalent melted diameter. The "intrinsic" shape is found to be very stable in the range 001.5, more scatter is observed, but future analysis should decide if it is representative of real physical variation or statistical "error" due to counting problem. Considering an overall statistics over the full data base, a large scatter of the N_0^* against Dm plot is found. But in the case of a particular event or a particular leg of a flight, the N_0^* vs. Dm plot is much less scattered and shows a systematic trend for decaying of N_0^* when Dm increases. This trend is interpreted as the manifestation of the predominance of the aggregation process. Finally an important point for cloud remote sensing is investigated : the normalised relationships IWC/N_0^* against Z/N_0^* is much less scattered that the classical IWC against Z the radar reflectivity factor.

  18. Influence of particle shape on the microstructure evolution and the mechanical properties of granular materials

    Science.gov (United States)

    Tian, Jianqiu; Liu, Enlong; Jiang, Lian; Jiang, Xiaoqiong; Sun, Yi; Xu, Ran

    2018-06-01

    In order to study the influence of particle shape on the microstructure evolution and the mechanical properties of granular materials, a two-dimensional DEM analysis of samples with three particle shapes, including circular particles, triangular particles, and elongated particles, is proposed here to simulate the direct shear tests of coarse-grained soils. For the numerical test results, analyses are conducted in terms of particle rotations, fabric evolution, and average path length evolution. A modified Rowe's stress-dilatancy equation is also proposed and successfully fitted onto simulation data.

  19. Variable property, steady, axi-symmetric, laminar, continuum plasma flow over spheroidal particles

    International Nuclear Information System (INIS)

    Wen Yuemin; Jog, Milind A.

    2005-01-01

    Steady, continuum, laminar plasma flow over spheroidal particles has been numerically investigated in this paper using a finite volume method. To body-fit the non-spherical particle surface, an adaptive orthogonal grid is generated. The flow field and the temperature distribution are calculated for oblate and prolate particle shapes. A number of particle surface temperatures and far field temperatures are considered and thermo-physical property variation is fully accounted for in our model. The particle shapes are represented in terms of axis ratio which is defined as the ratio of axis perpendicular to the flow direction to the axis along the flow direction. For oblate shape, axis ratios from 1.6 (disk-like) to 1 (sphere) are used whereas for prolate shape, axis ratios of 1(sphere) to 0.4 (cylinder-like) are used. Effects of flow Reynolds number, particle shape, surface and far field temperatures, and variable properties, on the flow field, temperature variations, drag coefficient, and Nusselt number are outlined. Results show that particle shape has significant effect on flow and heat transfer to particle surface. Compared to a constant property flow, accounting for thermo-physical property variation leads to prediction of higher temperature and velocity gradients in the vicinity of the particle surface. Based on the numerical results, a correlation for the Nusslet number is proposed that accounts for the effect of particle shape in continuum flow with large thermo-physical property variation

  20. Synthesis and surface properties of submicron barium sulfate particles

    International Nuclear Information System (INIS)

    Zhang Ming; Zhang Bao; Li Xinhai; Yin Zhoulan; Guo Xueyi

    2011-01-01

    Barium sulfate particles were synthesized in the presence of EDTA at room temperature. X-ray diffractometry (XRD), Fourier transform infrared resonance (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of BaSO 4 particles. The effect of the preparation parameters on the particle size distribution and morphology was investigated. The conditional formation constants of Ba-EDTA at different pH values were calculated. The results show that the size and morphology of BaSO 4 particles can be effectively controlled by adding EDTA in the precipitation process. Among all the operation conditions, the pH value has significant effect on the particle size. The obtained barium sulfate particles are spherical and well dispersed at pH = 9-10. Zeta potentials of BaSO 4 were measured at different pH. The isoelectric point (IEP) of barium sulfate colloid appears at pH 6.92. The model of the solid-solution interface at a particle of BaSO 4 was presented. The FTIR result indicates that the surface of the prepared BaSO 4 absorbs the functional groups of EDTA, which lower the IEP of the barium sulfate particles.

  1. Synthesis and surface properties of submicron barium sulfate particles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Ming, E-mail: csu.light@yahoo.com.cn [College of Chemistry and Chemical Engineering, Zhaoqing University, Zhaoqing 526061 (China); School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Zhang Bao; Li Xinhai [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Yin Zhoulan [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Guo Xueyi [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China)

    2011-10-15

    Barium sulfate particles were synthesized in the presence of EDTA at room temperature. X-ray diffractometry (XRD), Fourier transform infrared resonance (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of BaSO{sub 4} particles. The effect of the preparation parameters on the particle size distribution and morphology was investigated. The conditional formation constants of Ba-EDTA at different pH values were calculated. The results show that the size and morphology of BaSO{sub 4} particles can be effectively controlled by adding EDTA in the precipitation process. Among all the operation conditions, the pH value has significant effect on the particle size. The obtained barium sulfate particles are spherical and well dispersed at pH = 9-10. Zeta potentials of BaSO{sub 4} were measured at different pH. The isoelectric point (IEP) of barium sulfate colloid appears at pH 6.92. The model of the solid-solution interface at a particle of BaSO{sub 4} was presented. The FTIR result indicates that the surface of the prepared BaSO{sub 4} absorbs the functional groups of EDTA, which lower the IEP of the barium sulfate particles.

  2. 2D and 3D organisation of nano-particles: synthesis and specific properties

    International Nuclear Information System (INIS)

    Taleb, Abdelhafed

    1998-01-01

    The first part of this research thesis addresses the synthesis of nano-particles of silver and cobalt in the inverse micellar system, and highlights the feasibility of two- and three-dimensional structures of these particles. The author first presents the micellar system (micro-emulsions, surfactant, properties of inverse micelles, functionalized inverse micelles, application to the synthesis of nano-particles), and then reports the study of the synthesis and organisation of colloids in 2D and 3D. He also reports the study of optical properties of metallic colloids: free electron approximation, optical properties of electron gases, optical properties of colloids, optical response of two-dimensional and three-dimensional nano-structures. The magnetic properties of colloids are then studied: magnetism of the massive metallic state, magnetic properties of nano-particles (influence of size, interactions and field, notions of magnetic order and disorder), effect of organisation. The second part of this thesis is made of a set of published articles: Synthesis of highly mono-disperse silver nano-particles from AOT reverse micelles (a way to 2D and 3D self-organisation), Optical properties of self-assembled 2D and 3D super-lattices of silver nano-particles, Collective optical properties of silver nano-particles organised in 2D super-lattices, Self assembled in 2D cobalt nano-sized particles, Self organisation of magnetic nano-sized cobalt particles, Organisation in 2D cobalt nano-particles (synthesis, characterization and magnetic properties) [fr

  3. The effect of particles in different sizes on the mechanical properties of spray formed steel composites

    DEFF Research Database (Denmark)

    Petersen, Kenneth; Pedersen, A. S.; Pryds, N.

    2000-01-01

    particle size of 46 and 134 μm were carried out with respect to their mechanical properties e.g. wear resistance and tensile strength. It was found that the addition of Al2O3 particles to the steel improves its wear properties and reduces the elongation and tensile strength of the material......The main objective of the work was to investigate the effect of addition of ceramic particles with different size distributions on the mechanical properties, e.g. wear resistance and tensile strength, of spray formed materials. The experiments were carried out in a spray-forming unit at Risø...... National Laboratory, Denmark, where composites with a low alloyed boron steel (0.2 wt.% carbon) matrix containing alumina particles were produced. A comparison between cast hot-rolled material without particles, spray formed material without particles and the spray formed composites with an average ceramic...

  4. The effect of particle shape and size distribution on the acoustical properties of mixtures of hemp particles.

    Science.gov (United States)

    Glé, Philippe; Gourdon, Emmanuel; Arnaud, Laurent; Horoshenkov, Kirill-V; Khan, Amir

    2013-12-01

    Hemp concrete is an attractive alternative to traditional materials used in building construction. It has a very low environmental impact, and it is characterized by high thermal insulation. Hemp aggregate particles are parallelepiped in shape and can be organized in a plurality of ways to create a considerable proportion of open pores with a complex connectivity pattern, the acoustical properties of which have never been examined systematically. Therefore this paper is focused on the fundamental understanding of the relations between the particle shape and size distribution, pore size distribution, and the acoustical properties of the resultant porous material mixture. The sound absorption and the transmission loss of various hemp aggregates is characterized using laboratory experiments and three theoretical models. These models are used to relate the particle size distribution to the pore size distribution. It is shown that the shape of particles and particle size control the pore size distribution and tortuosity in shiv. These properties in turn relate directly to the observed acoustical behavior.

  5. Novel Online Diagnostic Analysis for In-Flight Particle Properties in Cold Spraying

    Science.gov (United States)

    Koivuluoto, Heli; Matikainen, Ville; Larjo, Jussi; Vuoristo, Petri

    2018-02-01

    In cold spraying, powder particles are accelerated by preheated supersonic gas stream to high velocities and sprayed on a substrate. The particle velocities depend on the equipment design and process parameters, e.g., on the type of the process gas and its pressure and temperature. These, in turn, affect the coating structure and the properties. The particle velocities in cold spraying are high, and the particle temperatures are low, which can, therefore, be a challenge for the diagnostic methods. A novel optical online diagnostic system, HiWatch HR, will open new possibilities for measuring particle in-flight properties in cold spray processes. The system employs an imaging measurement technique called S-PTV (sizing-particle tracking velocimetry), first introduced in this research. This technique enables an accurate particle size measurement also for small diameter particles with a large powder volume. The aim of this study was to evaluate the velocities of metallic particles sprayed with HPCS and LPCS systems and with varying process parameters. The measured in-flight particle properties were further linked to the resulting coating properties. Furthermore, the camera was able to provide information about variations during the spraying, e.g., fluctuating powder feeding, which is important from the process control and quality control point of view.

  6. Cosmological constraints on the properties of weakly interacting massive particles

    International Nuclear Information System (INIS)

    Steigman, G.; Turner, M.S.

    1984-10-01

    Considerations of the age and density of, as well as the evolution of structure in, the Universe lead to constraints on the masses and lifetimes of weakly interacting massive particles (WIMPs). 26 references

  7. Cosmological constraints on the properties of weakly interacting massive particles

    Energy Technology Data Exchange (ETDEWEB)

    Steigman, G.; Turner, M.S.

    1984-10-01

    Considerations of the age and density of, as well as the evolution of structure in, the Universe lead to constraints on the masses and lifetimes of weakly interacting massive particles (WIMPs). 26 references.

  8. Morphology and Optical Properties of Black-Carbon Particles Relevant to Engine Emissions

    Science.gov (United States)

    Michelsen, H. A.; Bambha, R.; Dansson, M. A.; Schrader, P. E.

    2013-12-01

    Black-carbon particles are believed to have a large influence on climate through direct radiative forcing, reduction of surface albedo of snow and ice in the cryosphere, and interaction with clouds. The optical properties and morphology of atmospheric particles containing black carbon are uncertain, and characterization of black carbon resulting from engines emissions is needed. Refractory black-carbon particles found in the atmosphere are often coated with unburned fuel, sulfuric acid, water, ash, and other combustion by-products and atmospheric constituents. Coatings can alter the optical and physical properties of the particles and therefore change their optical properties and cloud interactions. Details of particle morphology and coating state can also have important effects on the interpretation of optical diagnostics. A more complete understanding of how coatings affect extinction, absorption, and incandescence measurements is needed before these techniques can be applied reliably to a wide range of particles. We have investigated the effects of coatings on the optical and physical properties of combustion-generated black-carbon particles using a range of standard particle diagnostics, extinction, and time-resolved laser-induced incandescence (LII) measurements. Particles were generated in a co-flow diffusion flame, extracted, cooled, and coated with oleic acid. The diffusion flame produces highly dendritic soot aggregates with similar properties to those produced in diesel engines, diffusion flames, and most natural combustion processes. A thermodenuder was used to remove the coating. A scanning mobility particle sizer (SMPS) was used to monitor aggregate sizes; a centrifugal particle mass analyzer (CPMA) was used to measure coating mass fractions, and transmission electron microscopy (TEM) was used to characterize particle morphologies. The results demonstrate important differences in optical measurements between coated and uncoated particles.

  9. Investigation of some properties of the dielectric particle detector

    Energy Technology Data Exchange (ETDEWEB)

    Gavalyan, V.G.; Gukasyan, S.M.; Kavalov, R.L.; Karapetyan, R.A.; Lorikyan, M.P. (Erevanskij Fizicheskij Inst. (USSR))

    1981-01-01

    Results of investigation into temporary dispersion and amplitude resolution of a dielectric detector (DD) of particles are given. In this detector secondary electrons produced by a particle passing through a dielectric layer are gathered on thin anode filaments strenched inside the dielectric layer. As a working substance of the detector investigated used was CsI having 1.7% relative density of monocrystal, gap between planes of 20 ..mu..m diameter anode filaments and cathode electrodes was approximately equal to 200 ..mu..m, distance between anode filaments was approximately 250 ..mu..m. DD having working area S=5 cm/sup 2/ was placed at a distance of 2 cm from 5 MeV radioactive alpha source of 10/sup 4/ particle/s intensity. Curve of particle detection efficiency for this detector reached plateau at a level of 100% in the range of working voltages from 800 to 1200 V. Coincidence method together with a time-amplitude converter, at inlets of which applied were pulses from DD and a scintillation counter placed under DD, were used to measure temporary dispersion. Data on behaviour of particle registration efficiency depending on time of continuous effect of working and inverse voltages are given. It is found that temporary dispersion of the DD and scintillation counter system is a value of order of 1 ns and amplitude resolution of DD is an order of 100%.

  10. Properties of the particles emitted at mid-rapidity

    International Nuclear Information System (INIS)

    Lefort, T.; Cussol, D; Peter, J.; Bocage, F.; Bougault, R.; Brou, R.; Colin, J; Durand, D.; Genouin-Duhamel, E.; Gulminelli, F.; Lecolley, J.F.; Le Neindre, N.; Lopez, O.; Louvel, M.; Nguyen, A.D.; Steckmeyer, J. C.; Tamain, B.; Vient, E.

    1997-01-01

    Mid-rapidity emission studies allow the access at the very first instances of collision between two nuclei. Its study as a function of the energy of incident projectile permits to follow the evolution of the phenomena in the entrance channel from the lowest energies where these phenomena are essentially collective up to high energies where they are essentially governed by nucleon-nucleon collisions. The first method called the 'method E' consists in evaluating first the contribution of the quasi-projectile to the rapidity distribution and then to subtract it from the total spectrum to obtain the contribution from the mid-rapidity particles. For light particles the mid-rapidity emissions have a spectrum extended up to rapidities close to that of the quasi-projectile. This method under-estimates the contribution due to mid-rapidity. The second method called the 'method M' consists in determining directly the contribution from the mid-rapidity particles supposing that their rapidity spectrum is homothetic to the triton spectrum. This method over-estimates the contribution of mid-rapidity particles to the measure where the rapidity spectrum of the evaporated particles may extend up to Y nn , the rapidity of the nucleon-nucleon frame. The relative proportion of the particles coming from mid-rapidity emissions as a function of the experimental impact parameter and incident energy for the system Ar+Ni is shown. Also, results concerning the energy spectrum of light particles emitted at mid-rapidity as a function of the excitation energy of quasi-projectile are shown for the same system. Conclusions concerning the mid-rapidity emission are the following: the amount of particles depends essentially on the geometric overlap between the projectile and the target; these particles are issued out of a zone richer in neutrons than the total system; the energy per nucleon stored in this zone is independent of the violence of collision what indicates a production process essentially

  11. Internalisation of engineered nanoparticles into mammalian cells in vitro: influence of cell type and particle properties

    International Nuclear Information System (INIS)

    Busch, Wibke; Bastian, Susanne; Trahorsch, Ulrike; Iwe, Maria; Kühnel, Dana; Meißner, Tobias; Springer, Armin; Gelinsky, Michael; Richter, Volkmar; Ikonomidou, Chrysanthy; Potthoff, Annegret; Lehmann, Irina; Schirmer, Kristin

    2011-01-01

    Cellular internalisation of industrial engineered nanoparticles is undesired and a reason for concern. Here we investigated and compared the ability of seven different mammalian cell cultures in vitro to incorporate six kinds of engineered nanoparticles, focussing on the role of cell type and particle properties in particle uptake. Uptake was examined using light and electron microscopy coupled with energy dispersive X-ray spectroscopy (EDX) for particle element identification. Flow cytometry was applied for semi-quantitative analyses of particle uptake and for exploring the influence on uptake by the phagocytosis inhibitor Cytochalasin D (CytoD). All particles studied were found to enter each kind of cultured cells. Yet, particles were never found within cell nuclei. The presence of the respective particles within the cells was confirmed by EDX. Live-cell imaging revealed the time-dependent process of internalisation of technical nanoparticles, which was exemplified by tungsten carbide particle uptake into the human skin cells, HaCaT. Particles were found to co-localise with lysosomal structures within the cells. The incorporated nanoparticles changed the cellular granularity, as measured by flow cytometry, already after 3 h of exposure in a particle specific manner. By correlating particle properties with flow cytometry data, only the primary particle size was found to be a weakly influential property for particle uptake. CytoD, an inhibitor of actin filaments and therewith of phagocytosis, significantly inhibited the internalisation of particle uptake in only two of the seven investigated cell cultures. Our study, therefore, supports the notion that nanoparticles can enter mammalian cells quickly and easily, irrespective of the phagocytic ability of the cells.

  12. Acceleration of Particles as a Universal Property of Ergosphere

    Science.gov (United States)

    Zaslavskii, O. B.

    2013-04-01

    We show that recent observation made by Grib and Pavlov, [A. A. Grib and Yu. V. Pavlov, Europhys. Lett.101, 20004 (2013)] for the Kerr black hole is valid in the general case of rotating axially symmetric metric. Namely, collision of two particles in the ergosphere leads to indefinite growth of the energy in the center-of-mass frame, provided the angular momentum of one of the two particles is negative and increases without limit for a fixed energy at infinity. General approach enabled us to elucidate why the role of the ergosphere is crucial in this process.

  13. The Effects of Fe-Particles on the Tensile Properties of Al-Si-Cu Alloys

    Directory of Open Access Journals (Sweden)

    Anton Bjurenstedt

    2016-12-01

    Full Text Available The effect of Fe-rich particles has been a topic for discussion in the aluminum casting industry because of the negative impact they exert on the mechanical properties. However, there are still contradictions on the effects of various morphologies of Fe-particles. In this study, microstructural characterization of tensile tested samples has been performed to reveal how unmodified and modified Fe-rich particles impact on the tensile behavior. Analysis of additions of Fe modifiers such as Mn and Cr, showed higher amounts of primary Fe-rich particles (sludge with increased porosity and, as result, degraded tensile properties. From the fracture analysis of tensile tested hot isostatic pressed (HIPed samples it could be concluded that the mechanical properties were mainly governed by the Fe-rich particles, which were fracturing through cleavage, not by the porosity.

  14. Physical properties of the arctic summer aerosol particles in relation ...

    Indian Academy of Sciences (India)

    The sea-salt particles of marine origin generated within the Arctic circle are identified as the main source of the Arctic summer aerosols. ... concentration starts decreasing within a few minutes from the start of these events but requires a few hours to restore to the normal background aerosol level after the end of event.

  15. Decay properties of high-lying single-particles modes

    NARCIS (Netherlands)

    Beaumel, D; Fortier, S; Gales, S; Guillot, J; LangevinJoliot, H; Laurent, H; Maison, JM; Vernotte, J; Bordewijck, J; Brandenburg, S; Krasznahorkay, A; Crawley, GM; Massolo, CP; Renteria, M; Khendriche, A

    1996-01-01

    The neutron decay of high-lying single-particle states in Ni-64, Zr-90, Sn-120 and (208)pb excited by means of the (alpha,He-3) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular

  16. Physical properties of the arctic summer aerosol particles in relation ...

    Indian Academy of Sciences (India)

    tion associated with the winds from the oceanic sector is spread over the whole range of particle sizes, the increase in ... the levels at densely polluted urban areas. These changes ..... forest fires in Siberia or biomass burning in the. Eurasian ...

  17. Directive properties of active coated nano-particles

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, W.

    2012-01-01

    and optical gain constant on the directivities. While significant variations in the directivities are realized in the cylindrical cases for different source locations within and slightly outside the nano-particles and values of the optical gain constant, the corresponding spherical cases exhibit negligible...

  18. Constraining properties of dark matter particles using astrophysical data

    NARCIS (Netherlands)

    Iakubovskyi, Dmytro

    2013-01-01

    A microscopic origin of dark matter phenomenon is the most plausible hypothesis to explain the mystery of dark matter. The dark matter particle hypothesis necessarily implies an extension of the Standard Model. In this thesis, we undertook a systematic model-independent program of studying the

  19. Single-particle properties from Kohn-Sham Green's functions

    International Nuclear Information System (INIS)

    Bhattacharyya, Anirban; Furnstahl, R.J.

    2005-01-01

    An effective action approach to Kohn-Sham density functional theory is used to illustrate how the exact Green's function can be calculated in terms of the Kohn-Sham Green's function. An example based on Skyrme energy functionals shows that single-particle Kohn-Sham spectra can be improved by adding sources used to construct the energy functional

  20. Size-resolved chemical composition, effective density, and optical properties of biomass burning particles

    Science.gov (United States)

    Zhai, Jinghao; Lu, Xiaohui; Li, Ling; Zhang, Qi; Zhang, Ci; Chen, Hong; Yang, Xin; Chen, Jianmin

    2017-06-01

    Biomass burning aerosol has an important impact on the global radiative budget. A better understanding of the correlations between the mixing states of biomass burning particles and their optical properties is the goal of a number of current studies. In this work, the effective density, chemical composition, and optical properties of rice straw burning particles in the size range of 50-400 nm were measured using a suite of online methods. We found that the major components of particles produced by burning rice straw included black carbon (BC), organic carbon (OC), and potassium salts, but the mixing states of particles were strongly size dependent. Particles of 50 nm had the smallest effective density (1.16 g cm-3) due to a relatively large proportion of aggregate BC. The average effective densities of 100-400 nm particles ranged from 1.35 to 1.51 g cm-3 with OC and inorganic salts as dominant components. Both density distribution and single-particle mass spectrometry showed more complex mixing states in larger particles. Upon heating, the separation of the effective density distribution modes confirmed the external mixing state of less-volatile BC or soot and potassium salts. The size-resolved optical properties of biomass burning particles were investigated at two wavelengths (λ = 450 and 530 nm). The single-scattering albedo (SSA) showed the lowest value for 50 nm particles (0.741 ± 0.007 and 0.889 ± 0.006) because of the larger proportion of BC content. Brown carbon played an important role for the SSA of 100-400 nm particles. The Ångström absorption exponent (AAE) values for all particles were above 1.6, indicating the significant presence of brown carbon in all sizes. Concurrent measurements in our work provide a basis for discussing the physicochemical properties of biomass burning aerosol and its effects on the global climate and atmospheric environment.

  1. A database of microwave and sub-millimetre ice particle single scattering properties

    Science.gov (United States)

    Ekelund, Robin; Eriksson, Patrick

    2016-04-01

    Ice crystal particles are today a large contributing factor as to why cold-type clouds such as cirrus remain a large uncertainty in global climate models and measurements. The reason for this is the complex and varied morphology in which ice particles appear, as compared to liquid droplets with an in general spheroidal shape, thus making the description of electromagnetic properties of ice particles more complicated. Single scattering properties of frozen hydrometers have traditionally been approximated by representing the particles as spheres using Mie theory. While such practices may work well in radio applications, where the size parameter of the particles is generally low, comparisons with measurements and simulations show that this assumption is insufficient when observing tropospheric cloud ice in the microwave or sub-millimetre regions. In order to assist the radiative transfer and remote sensing communities, a database of single scattering properties of semi-realistic particles is being produced. The data is being produced using DDA (Discrete Dipole Approximation) code which can treat arbitrarily shaped particles, and Tmatrix code for simpler shapes when found sufficiently accurate. The aim has been to mainly cover frequencies used by the upcoming ICI (Ice Cloud Imager) mission with launch in 2022. Examples of particles to be included are columns, plates, bullet rosettes, sector snowflakes and aggregates. The idea is to treat particles with good average optical properties with respect to the multitude of particles and aggregate types appearing in nature. The database will initially only cover macroscopically isotropic orientation, but will eventually also include horizontally aligned particles. Databases of DDA particles do already exist with varying accessibility. The goal of this database is to complement existing data. Regarding the distribution of the data, the plan is that the database shall be available in conjunction with the ARTS (Atmospheric

  2. Characterization of the geometrical properties of agglomerated aerosol particles

    International Nuclear Information System (INIS)

    Weber, A.P.

    1992-12-01

    A method for the absolute mass determination of agglomerated aerosol particles is presented. Based on this method it is possible to determine simultaneously and in situ mass, exposed surface and mobility diameter. From these measurements the fractal dimension of aerosol particles can be derived. For silver agglomerates produced by spark discharge it was found that they are bifractal. The fractal dimension was 3 in the free molecular regime and 1.9 in the transition regime. By variation of the gas mean free path it was shown that the region where the agglomerate structure changes from close-packed particle to low density agglomerates depends on the Knudsen number. In the free molecular regime the fractal dimension was not at all affected by any change of the generation conditions. Only sintering caused an increase in the density which was attributed to mass transport within the agglomerate. In the transition regime the fractal dimension remained constant with increasing monomer concentration and with increasing flow rate, but it increased with increasing pressure, increasing Ar:He ratio and with increasing sintering temperature. For sintering this effect was explained by the minimization of the surface free energy. It was found that the structure changing rate is proportional to the product of sintering temperature and residence time in the sintering oven. By carefully adjusting the temperature it is possible to produce agglomerates of a well defined structure. In desorption experiments of 136 I from silver and carbon agglomerates it could be shown that the desorption behavior is different. It was found that the desorption enthalpy of iodine from graphite and silver particles were -142 kJ/mol and -184 kJ/mol, respectively. Moreover, it was demonstrated that the 136 I attachment to particles is different for silver agglomerates with the same mobility, but different structures. (author) 41 figs., refs

  3. Effects of cement particle size distribution on performance properties of Portland cement-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, D.P.; Garboczi, E.J.; Haecker, C.J.; Jensen, O.M.

    1999-10-01

    The original size, spatial distribution, and composition of Portland cement particles have a large influence on hydration kinetics, microstructure development, and ultimate properties of cement-based materials. In this paper, the effects of cement particle size distribution on a variety of performance properties are explored via computer simulation and a few experimental studies. Properties examined include setting time, heat release, capillary porosity percolation, diffusivity, chemical shrinkage, autogenous shrinkage, internal relative humidity evolution, and interfacial transition zone microstructure. The effects of flocculation and dispersion of the cement particles in the starting microstructures on resultant properties are also briefly evaluated. The computer simulations are conducted using two cement particle size distributions that bound those commonly in use today and three different water-to-cement ratios: 0.5, 0.3, and 0.246. For lower water-to-cement ratio systems, the use of coarser cements may offer equivalent or superior performance, as well as reducing production costs for the manufacturer.

  4. Optical properties and quantum confinement of nanocrystalline II-IV semiconductor particles

    NARCIS (Netherlands)

    Dijken, Albert van

    1999-01-01

    In this thesis, experiments are described that were performed on suspensions of nanocrystalline II-IV semiconductor particles.The object of this research is to study quantum size effects in relation to the luminescence properties of these particles. A pre-requisite for performing studies of

  5. Effect of particle size of granules on some mechanical properties of ...

    African Journals Online (AJOL)

    Solid dosage forms are invariably multiparticulate systems of heterogenous particle size distribution. The purpose of this study was to investigate the effect of particle size distribution of paracetamol granules on some tablet mechanical properties of paracetamol tablets. Granules were formed by wet massing paracetamol ...

  6. Determining the radiative properties of pulverized-coal particles from experiments. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Menguec, M.P.

    1992-02-01

    A comprehensive coupled experimental-theoretical study has been performed to determine the effective radiative properties of pulverized-coal/char particles. The results obtained show that the ``effective`` scattering phase function of coal particles are highly forward scattering and show less sensitivity to the size than predicted from the Lorenz-Mie theory. The main reason for this is the presence of smaller size particles associated with each larger particle. Also, the coal/char particle clouds display more side scattering than predicted for the same size range spheres, indicating the irregular shape of the particles and fragmentation. In addition to these, it was observed that in the visible wavelength range the coal absorption is not gray, and slightly vary with the wavelength. These two experimental approaches followed in this study are unique in a sense that the physics of the problem are not approximated. The properties determined include all uncertainties related to the particle shape, size distribution, inhomogeneity and spectral complex index of refraction data. In order to obtain radiative property data over a wider wavelength spectrum, additional ex-situ experiments have been carried out using a Fourier Transform Infrared (FT-IR) Spectrometer. The spectral measurements were performed over the wavelength range of 2 to 22 {mu}m. These results were interpreted to obtain the ``effective`` efficiency factors of coal particles and the corresponding refractive index values. The results clearly show that the coal/char radiative properties display significant wavelength dependency in the infrared spectrum.

  7. Influence of layer eccentricity on the resonant properties of cylindrical active coated nano-particles

    DEFF Research Database (Denmark)

    Thorsen, R. O.; Arslanagic, Samel

    2015-01-01

    We report on the influence of the layer eccentricity on the resonant properties of active coated nano-particles made of a silver core and gain impregnated silica shell illuminated by a near-by magnetic line source. For a fixed over-all size of the particle, designs with small and large cores...

  8. Vertical Profiles and Chemical Properties of Aerosol Particles upon Ny-Ålesund (Svalbard Islands

    Directory of Open Access Journals (Sweden)

    B. Moroni

    2015-01-01

    Full Text Available Size-segregated particle samples were collected in the Arctic (Ny-Ålesund, Svalbard in April 2011 both at ground level and in the free atmosphere exploiting a tethered balloon equipped also with an optical particle counter (OPC and meteorological sensors. Individual particle properties were investigated by scanning electron microscopy coupled with energy dispersive microanalysis (SEM-EDS. Results of the SEM-EDS were integrated with particle size and optical measurements of the aerosols properties at ground level and along the vertical profiles. Detailed analysis of two case studies reveals significant differences in composition despite the similar structure (layering and the comparable texture (grain size distribution of particles in the air column. Differences in the mineral chemistry of samples point at both local (plutonic/metamorphic complexes in Svalbard and remote (basic/ultrabasic magmatic complexes in Greenland and/or Iceland geological source regions for dust. Differences in the particle size and shape are put into relationship with the mechanism of particle formation, that is, primary (well sorted, small or secondary (idiomorphic, fine to coarse grained origin for chloride and sulfate crystals and transport/settling for soil (silicate, carbonate and metal oxide particles. The influence of size, shape, and mixing state of particles on ice nucleation and radiative properties is also discussed.

  9. Hygroscopic Properties and Chemical Composition of Aerosol Particles at the High Alpine Site Jungfraujoch

    Energy Technology Data Exchange (ETDEWEB)

    Weingarter, E.; Gysel, M.; Sjoegren, S.; Baltesperger, U.; Alfarra, R.; Bower, K.; Coe, H.

    2004-03-01

    The hygroscopic properties of aerosols play a significant role in atmospheric phenomena such as acid deposition, visibility degradation and climate change. Due to the hygroscopic growth of the particles, water is often the dominant component of the ambient aerosol at high relative humidity (RH) conditions. The ability to absorb water depends on the particle chemical composition, dry size, and shape. The aim of this study is to link the chemical composition of the atmospheric aerosol to its hygroscopic properties. (author)

  10. Synthesis and properties of unagglomerated nanocomposite particles for nanomedical applications

    Science.gov (United States)

    Rouse, Sarah M.

    2005-11-01

    Methods have been developed to prepare stable, unagglomerated active-medical-agent nanoparticles in a range of sizes, based on reverse-micelle microemulsion techniques. The process used to prepare monodisperse, spherical nanocomposite particles is based on methods originally outlined in detail by Adair et al. and Li et al. The "Molecular Dot" (MD) nanoparticles incorporate a variety of medically-active substances, such as organic fluorophores and therapeutic drugs, internally distributed in silica, titania, calcium phosphate, or calcium phospho-silicate matrices. The synthesis techniques have also been modified to produce nanoparticles containing combinations of fluorophores and medicinal agents, in order to monitor drug release and location. The specific biomedical application for the nanocomposite particles dictates the selection of core and shell-matrix materials. For example, the protective shell-matrices of the silica and titania MDs shield the active-medical agents from damage due to changes in pH, temperature, and other environmental effects. Conversely, the calcium phosphate and calcium phospho-silicate shell-matrix nanoparticles can potentially be engineered to dissolve in physiological environments. The method used to remove residual precursor materials while maintaining a well-dispersed assembly of nanoparticles is critical to the use of nanocolloids in medical applications. The dispersion approach is based on protection-dispersion theory tailored to accommodate the high surface areas and reactivity of sub-50 nm particles in aqueous or water/ethanol mixtures. Dispersion of the nanocomposite particles is further enhanced with the use of size-exclusion high performance liquid chromatography (HPLC) to simultaneously wash and disperse the nanocomposite particle suspensions. The state of dispersion of the nanosuspensions is evaluated using the average agglomeration number (AAN) approach in conjunction with other characterization techniques. The formulation of

  11. Bio-composites based on polypropylene reinforced with Almond Shells particles: Mechanical and thermal properties

    International Nuclear Information System (INIS)

    Essabir, H.; Nekhlaoui, S.; Malha, M.; Bensalah, M.O.; Arrakhiz, F.Z.; Qaiss, A.; Bouhfid, R.

    2013-01-01

    Highlights: • Almond Shells (ASs) particles have been used as reinforcement in polypropylene matrix. • The SEBS-g-MA has been used to improve the adhesion between matrix and particles. • The mechanical and thermal properties of the composite have been improved by the AS. - Abstract: In this work, Almond Shells (ASs) particles are used as reinforcement in a thermoplastic matrix as polypropylene (PP). Composites containing Almond Shells (ASs) particles with and without compatibilizer (maleic anhydride grafted polypropylene; SEBS-g-MA) for various particle content (5, 10, 15, 20, 25, 30 wt.%) was investigated by means of studying their mechanical, thermal and rheological properties. The composites were prepared in a twin-screw extruder and assessed by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), tensile testing and Dynamic Mechanical Analysis (DMA). Results show a clear improvement in mechanical and rheological properties from the use of Almond Shells particles in the matrix without and with maleic anhydride compatibilizer, corresponding to a gain in Young’s modulus of 56.2% and 35% respectively, at 30 wt.% particle loading. Thermal analysis revealed that incorporation of particle in the composites resulted in increase in the initial thermal decomposition temperatures

  12. The Microwave Properties of Simulated Melting Precipitation Particles: Sensitivity to Initial Melting

    Science.gov (United States)

    Johnson, B. T.; Olson, W. S.; Skofronick-Jackson, G.

    2016-01-01

    A simplified approach is presented for assessing the microwave response to the initial melting of realistically shaped ice particles. This paper is divided into two parts: (1) a description of the Single Particle Melting Model (SPMM), a heuristic melting simulation for ice-phase precipitation particles of any shape or size (SPMM is applied to two simulated aggregate snow particles, simulating melting up to 0.15 melt fraction by mass), and (2) the computation of the single-particle microwave scattering and extinction properties of these hydrometeors, using the discrete dipole approximation (via DDSCAT), at the following selected frequencies: 13.4, 35.6, and 94.0GHz for radar applications and 89, 165.0, and 183.31GHz for radiometer applications. These selected frequencies are consistent with current microwave remote-sensing platforms, such as CloudSat and the Global Precipitation Measurement (GPM) mission. Comparisons with calculations using variable-density spheres indicate significant deviations in scattering and extinction properties throughout the initial range of melting (liquid volume fractions less than 0.15). Integration of the single-particle properties over an exponential particle size distribution provides additional insight into idealized radar reflectivity and passive microwave brightness temperature sensitivity to variations in size/mass, shape, melt fraction, and particle orientation.

  13. Optical properties, morphology and elemental composition of atmospheric particles at T1 supersite on MILAGRO campaign

    Science.gov (United States)

    Carabali, G.; Mamani-Paco, R.; Castro, T.; Peralta, O.; Herrera, E.; Trujillo, B.

    2012-03-01

    Atmospheric particles were sampled at T1 supersite during MILAGRO campaign, in March 2006. T1 was located at the north of Mexico City (MC). Aerosol sampling was done by placing copper grids for Transmission Electron Microscope (TEM) on the last five of an 8-stage MOUDI cascade impactor. Samples were obtained at different periods to observe possible variations on morphology. Absorption and scattering coefficients, as well as particle concentrations (0.01-3 μm aerodynamic diameter) were measured simultaneously using a PSAP absorption photometer, a portable integrating nephelometer, and a CPC particle counter. Particle images were acquired at different magnifications using a CM 200 Phillips TEM-EDAX system, and then calculated the border-based fractal dimension. Also, Energy Dispersive X-Ray Spectroscopy (EDS) was used to determine the elemental composition of particles. The morphology of atmospheric particles for two aerodynamic diameters (0.18 and 1.8 μm) was compared using border-based fractal dimension to relate it to the other particle properties, because T1-generated particles have optical, morphological and chemical properties different from those transported by the MC plume. Particles sampled under MC pollution influence showed not much variability, suggesting that more spherical particles (border-based fractal dimension close to 1.0) are more common in larger sizes (d50 = 1.8 μm), which may be attributed to aerosol aging and secondary aerosol formation. Between 06:00 and 09:00 a.m., smaller particles (d50 = 0.18 μm) had more irregular shapes resulting in higher border-based fractal dimensions (1.2-1.3) for samples with more local influence. EDS analysis in d50 = 0.18 μm particles showed high contents of carbonaceous material, Si, Fe, K, and Co. Perhaps, this indicates an impact from industrial and vehicle emissions on atmospheric particles at T1.

  14. Decay properties of high-lying single-particles modes

    Science.gov (United States)

    Beaumel, D.; Fortier, S.; Galès, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J. M.; Vernotte, J.; Bordewijck, J.; Brandenburg, S.; Krasznahorkay, A.; Crawley, G. M.; Massolo, C. P.; Renteria, M.; Khendriche, A.

    1996-02-01

    The neutron decay of high-lying single-particle states in 64Ni, 90Zr, 120Sn and 208Pb excited by means of the (α, 3He) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular correlation analysis. The structure located between 11 and 15 MeV in 91Zr, and between 8 and 12 MeV excitation energy in 209Pb display large departures from a pure statistical decay. The corresponding non-statistical branching ratios are compared with the results of two theoretical calculations.

  15. Effect of nanodiamond particles on properties of epoxy composites

    Czech Academy of Sciences Publication Activity Database

    Špitalský, Z.; Kromka, Alexander; Matějka, Libor; Černoch, Peter; Kovářová, Jana; Kotek, Jiří; Šlouf, Miroslav

    2008-01-01

    Roč. 17, č. 1 (2008), s. 29-34 ISSN 0963-6935 R&D Projects: GA MŠk LC510; GA AV ČR IAA400500701 Grant - others:EU FP6 Marie Curie RTN DRIVE(XE) MRTN-CT-2004-512224 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z40500505 Keywords : nanodiamond * carbon nanotubes * mechanical properties * thermal properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.270, year: 2008

  16. Temperature dependence of single-particle properties in nuclear matter

    International Nuclear Information System (INIS)

    Zuo, W.; Lu, G.C.; Li, Z.H.; Lombardo, U.; Schulze, H.-J.

    2006-01-01

    The single-nucleon potential in hot nuclear matter is investigated in the framework of the Brueckner theory by adopting the realistic Argonne V 18 or Nijmegen 93 two-body nucleon-nucleon interaction supplemented by a microscopic three-body force. The rearrangement contribution to the single-particle potential induced by the ground state correlations is calculated in terms of the hole-line expansion of the mass operator and provides a significant repulsive contribution in the low-momentum region around and below the Fermi surface. Increasing temperature leads to a reduction of the effect, while increasing density makes it become stronger. The three-body force suppresses somewhat the ground state correlations due to its strong short-range repulsion, increasing with density. Inclusion of the three-body force contribution results in a quite different temperature dependence of the single-particle potential at high enough densities as compared to that adopting the pure two-body force. The effects of three-body force and ground state correlations on the nucleon effective mass are also discussed

  17. Particle size distribution of rice flour affecting the starch enzymatic hydrolysis and hydration properties.

    Science.gov (United States)

    de la Hera, Esther; Gomez, Manuel; Rosell, Cristina M

    2013-10-15

    Rice flour is becoming very attractive as raw material, but there is lack of information about the influence of particle size on its functional properties and starch digestibility. This study evaluates the degree of dependence of the rice flour functional properties, mainly derived from starch behavior, with the particle size distribution. Hydration properties of flours and gels and starch enzymatic hydrolysis of individual fractions were assessed. Particle size heterogeneity on rice flour significantly affected functional properties and starch features, at room temperature and also after gelatinization; and the extent of that effect was grain type dependent. Particle size heterogeneity on rice flour induces different pattern in starch enzymatic hydrolysis, with the long grain having slower hydrolysis as indicated the rate constant (k). No correlation between starch digestibility and hydration properties or the protein content was observed. It seems that in intact granules interactions with other grain components must be taken into account. Overall, particle size fractionation of rice flour might be advisable for selecting specific physico-chemical properties. Copyright © 2013. Published by Elsevier Ltd.

  18. Voltage-Induced Nonlinear Conduction Properties of Epoxy Resin/Micron-Silver Particles Composites

    Science.gov (United States)

    Qu, Zhaoming; Lu, Pin; Yuan, Yang; Wang, Qingguo

    2018-01-01

    The nonlinear conduction properties of epoxy resin (ER)/micron-silver particles (MP) composites were investigated. Under sufficient high intensity applied constant voltage, the obvious nonlinear conduction properties of the samples with volume fraction 25% were found. With increments in the voltage, the conductive switching effect was observed. The nonlinear conduction mechanism of the ER/MP composites under high applied voltages could be attributed to the electrical current conducted via discrete paths of conductive particles induced by the electric field. The test results show that the ER/MP composites with nonlinear conduction properties are of great potential application in electromagnetic protection of electron devices and systems.

  19. Decay properties of high-lying single-particles modes

    Energy Technology Data Exchange (ETDEWEB)

    Beaumel, D. [Institut de Physique Nucleaire, 91 - Orsay (France); Fortier, S. [Institut de Physique Nucleaire, 91 - Orsay (France); Gales, S. [Institut de Physique Nucleaire, 91 - Orsay (France); Guillot, J. [Institut de Physique Nucleaire, 91 - Orsay (France); Langevin-Joliot, H. [Institut de Physique Nucleaire, 91 - Orsay (France); Laurent, H. [Institut de Physique Nucleaire, 91 -Orsay (France); Maison, J.M. [Institut de Physique Nucleaire, 91 - Orsay (France); Vernotte, J. [Institut de Physique Nucleaire, 91 - Orsay (France); Bordewijck, J. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Brandenburg, S. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Krasznahorkay, A. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Crawley, G.M. [NSCL, Michigan State University, East Lansing, MI 48824 (United States); Massolo, C.P. [Universitad Nacional de La Plata, 1900 La Plata (Argentina); Renteria, M. [Universitad Nacional de La Plata, 1900 La Plata (Argentina); Khendriche, A. [University of Tizi-Ouzou, Tizi-Ouzou (Algeria)

    1996-03-18

    The neutron decay of high-lying single-particle states in {sup 64}Ni, {sup 90}Zr, {sup 120}Sn and {sup 208}Pb excited by means of the ({alpha},{sup 3}He) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular correlation analysis. The structure located between 11 and 15 MeV in {sup 91}Zr, and between 8 and 12 MeV excitation energy in {sup 209}Pb display large departures from a pure statistical decay. The corresponding non-statistical branching ratios are compared with the results of two theoretical calculations. (orig.).

  20. Size distribution and hygroscopic properties of aerosol particles from dry-season biomass burning in Amazonia

    Directory of Open Access Journals (Sweden)

    J. Rissler

    2006-01-01

    Full Text Available Aerosol particle number size distributions and hygroscopic properties were measured at a pasture site in the southwestern Amazon region (Rondonia. The measurements were performed 11 September-14 November 2002 as part of LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate, and cover the later part of the dry season (with heavy biomass burning, a transition period, and the onset of the wet period. Particle number size distributions were measured with a DMPS (Differential Mobility Particle Sizer, 3-850nm and an APS (Aerodynamic Particle Sizer, extending the distributions up to 3.3 µm in diameter. An H-TDMA (Hygroscopic Tandem Differential Mobility Analyzer measured the hygroscopic diameter growth factors (Gf at 90% relative humidity (RH, for particles with dry diameters (dp between 20-440 nm, and at several occasions RH scans (30-90% RH were performed for 165nm particles. These data provide the most extensive characterization of Amazonian biomass burning aerosol, with respect to particle number size distributions and hygroscopic properties, presented until now. The evolution of the convective boundary layer over the course of the day causes a distinct diel variation in the aerosol physical properties, which was used to get information about the properties of the aerosol at higher altitudes. The number size distributions averaged over the three defined time periods showed three modes; a nucleation mode with geometrical median diameters (GMD of ~12 nm, an Aitken mode (GMD=61-92 nm and an accumulation mode (GMD=128-190 nm. The two larger modes were shifted towards larger GMD with increasing influence from biomass burning. The hygroscopic growth at 90% RH revealed a somewhat external mixture with two groups of particles; here denoted nearly hydrophobic (Gf~1.09 for 100 nm particles and moderately hygroscopic (Gf~1.26. While the hygroscopic growth factors were surprisingly similar over the

  1. Prediction of elastic properties for polymer-particle nanocomposites exhibiting an interphase

    International Nuclear Information System (INIS)

    Deng Fei; Van Vliet, Krystyn J

    2011-01-01

    Particle-polymer nanocomposites often exhibit mechanical properties described poorly by micromechanical models that include only the particle and matrix phases. Existence of an interfacial region between the particle and matrix, or interphase, has been posited and indirectly demonstrated to account for this effect. Here, we present a straightforward analytical approach to estimate effective elastic properties of composites comprising particles encapsulated by an interphase of finite thickness and distinct elastic properties. This explicit solution can treat nanocomposites that comprise either physically isolated nanoparticles or agglomerates of such nanoparticles; the same framework can also treat physically isolated nanoparticle aggregates or agglomerates of such aggregates. We find that the predicted elastic moduli agree with experiments for three types of particle-polymer nanocomposites, and that the predicted interphase thickness and stiffness of carbon black-rubber nanocomposites are consistent with measured values. Finally, we discuss the relative influence of the particle-polymer interphase thickness and stiffness to identify maximum possible changes in the macroscale elastic properties of such materials.

  2. Effect of the primary particle morphology on the micromechanical properties of nanostructured alumina agglomerates

    International Nuclear Information System (INIS)

    Schilde, Carsten; Westphal, Bastian; Kwade, Arno

    2012-01-01

    Depending on the application of nanoparticles, certain characteristics of the product quality such as size, morphology, abrasion resistance, specific surface, dispersibility and tendency to agglomeration are important. These characteristics are a function of the physicochemical properties, i.e. the micromechanical properties of the nanostructured material. The micromechanical properties of these nanostructured agglomerates such as the maximum indentation force, the plastic and elastic deformation energy and the strength give information on the product properties, e.g. the efficiency of a dispersion process of the agglomerates, and can be measured by nanoindentation. In this study a Berkovich indenter tip was used for the characterisation of model aggregates out of sol–gel produced silica and precipitated alumina agglomerates with different primary particle morphologies (dimension of 15–40 nm). In general, the effect of the primary particle morphology and the presence or absence of solid bonds can be characterised by the measurement of the micromechanical properties via nanoindentation. The micromechanical behaviour of aggregates containing solid bonds is strongly affected by the elastic–plastic deformation behaviour of the solid bonds and the breakage of solid bonds. Moreover, varying the primary particle morphology for similar particle material and approximately isotropic agglomerate behaviour the particle–particle interactions within the agglomerates can be described by the elementar breaking stress according to the formula of Rumpf.

  3. Relation between particle size and properties of some bituminous coals

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, A.D.; Cheng, M.; Goulet, J.-C.; Furimsky, E. (CANMET, Ottawa, ON (Canada). Energy Research Laboratories)

    1990-02-01

    Coal fractions of different size distributions exhibited different H/C ratio, ash and sulphur contents, and surface structures. This was confirmed using two low-sulphur and two high-sulphur bituminous coals. The effect was much less pronounced for low-sulphur coals than for high-sulphur coals. A significant difference in properties was noted between the two high-sulphur coals in spite of similar basic compositional parameters. This was confirmed by the fractal dimensionality factor D of Illinois No. 6 coal, which exceeded the theoretical value. 14 refs., 9 figs., 5 tabs.

  4. Mass spectrometric analysis and aerodynamic properties of various types of combustion-related aerosol particles

    Science.gov (United States)

    Schneider, J.; Weimer, S.; Drewnick, F.; Borrmann, S.; Helas, G.; Gwaze, P.; Schmid, O.; Andreae, M. O.; Kirchner, U.

    2006-12-01

    Various types of combustion-related particles in the size range between 100 and 850 nm were analyzed with an aerosol mass spectrometer and a differential mobility analyzer. The measurements were performed with particles originating from biomass burning, diesel engine exhaust, laboratory combustion of diesel fuel and gasoline, as well as from spark soot generation. Physical and morphological parameters like fractal dimension, effective density, bulk density and dynamic shape factor were derived or at least approximated from the measurements of electrical mobility diameter and vacuum aerodynamic diameter. The relative intensities of the mass peaks in the mass spectra obtained from particles generated by a commercial diesel passenger car, by diesel combustion in a laboratory burner, and by evaporating and re-condensing lubrication oil were found to be very similar. The mass spectra from biomass burning particles show signatures identified as organic compounds like levoglucosan but also others which are yet unidentified. The aerodynamic behavior yielded a fractal dimension (Df) of 2.09 +/- 0.06 for biomass burning particles from the combustion of dry beech sticks, but showed values around three, and hence more compact particle morphologies, for particles from combustion of more natural oak. Scanning electron microscope images confirmed the finding that the beech combustion particles were fractal-like aggregates, while the oak combustion particles displayed a much more compact shape. For particles from laboratory combusted diesel fuel, a Df value of 2.35 was found, for spark soot particles, Df [approximate] 2.10. The aerodynamic properties of fractal-like particles from dry beech wood combustion indicate an aerodynamic shape factor [chi] that increases with electrical mobility diameter, and a bulk density of 1.92 g cm-3. An upper limit of [chi] [approximate] 1.2 was inferred for the shape factor of the more compact particles from oak combustion.

  5. The necessity of microscopy to characterize the optical properties of size-selected, nonspherical aerosol particles.

    Science.gov (United States)

    Veghte, Daniel P; Freedman, Miriam A

    2012-11-06

    It is currently unknown whether mineral dust causes a net warming or cooling effect on the climate system. This uncertainty stems from the varied and evolving shape and composition of mineral dust, which leads to diverse interactions of dust with solar and terrestrial radiation. To investigate these interactions, we have used a cavity ring-down spectrometer to study the optical properties of size-selected calcium carbonate particles, a reactive component of mineral dust. The size selection of nonspherical particles like mineral dust can differ from spherical particles in the polydispersity of the population selected. To calculate the expected extinction cross sections, we use Mie scattering theory for monodisperse spherical particles and for spherical particles with the polydispersity observed in transmission electron microscopy images. Our results for calcium carbonate are compared to the well-studied system of ammonium sulfate. While ammonium sulfate extinction cross sections agree with Mie scattering theory for monodisperse spherical particles, the results for calcium carbonate deviate at large and small particle sizes. We find good agreement for both systems, however, between the calculations performed using the particle images and the cavity ring-down data, indicating that both ammonium sulfate and calcium carbonate can be treated as polydisperse spherical particles. Our results indicate that having an independent measure of polydispersity is essential for understanding the optical properties of nonspherical particles measured with cavity ring-down spectroscopy. Our combined spectroscopy and microscopy techniques demonstrate a novel method by which cavity ring-down spectroscopy can be extended for the study of more complex aerosol particles.

  6. Local analyticity properties of the n particle scattering amplitude

    CERN Document Server

    Bros, J; Glaser, Vladimir Jurko

    1972-01-01

    The connected part F/sub /c(p) of the scattering amplitude (p/sub 1 /...p/sub /r mod S-1 mod p/sub r+1/,..., p/sub n/) defined on the mass shell p/sub i//sup 2/=m/sub i//sup 2/ and deduced from a local field theory involving only (stable) particles with strictly positive masses can be represented in a suitable neighbourhood of any physical point p as a finite sum f/sub /c(p)= Sigma /sub 1//sup N/F/sub i/(p) of partial amplitudes', each F/sub i/(k) analytic in a certain domain F /sub i/ of the complex mass shell k/sub i//sup 2/=m/sub i//sup 2/. The mentioned real neighbourhood lies on the boundary of each F/sub i/. The above decomposition may fail to hold only at points p where any two incoming or any two outgoing four-momenta become parallel (thresholds). The number N as well as the shape of the domains F/sub i / depend on the number n and on the real neighbourhood considered. For a generic configuration p the intersection of the domains F/sub i/ is empty. When this does not happen, F/sub i/(p) is the boundar...

  7. Structural and fractal properties of particles emitted from spark ignition engines.

    Science.gov (United States)

    Chakrabarty, Rajan K; Moosmüller, Hans; Arnott, W Patrick; Garro, Mark A; Walker, John

    2006-11-01

    Size, morphology, and microstructure of particles emitted from one light-duty passenger vehicle (Buick Century; model year 1990; PM (particulate matter) mass emission rate 3.1 mg/km) and two light-duty trucks (Chevrolet C2; model year 1973; PM mass emission rate 282 mg/km, and Chevrolet El Camino; model year 1976; PM mass emission rate 31 mg/km), running California's unified driving cycles (UDC) on a chassis dynamometer, were studied using scanning electron microscopy (SEM). SEM images yielded particle properties including three-dimensional density fractal dimensions, monomer and agglomerate number size distributions, and three different shape descriptors, namely aspect ratio, root form factor, and roundness. The density fractal dimension of the particles was between 1.7 and 1.78, while the number size distribution of the particles placed the majority of the particles in the accumulation mode (0.1-0.3 microm). The shape descriptors were found to decrease with increasing particle size. Partial melting of particles, a rare and previously unreported phenomenon, was observed upon exposure of particles emitted during phase 2 of the UDC to the low accelerating voltage electron beam of the SEM. The rate of melting was quantified for individual particles, establishing a near linear relationship between the melting rate and the organic carbon 1 to elemental carbon ratio.

  8. Influence of complex particle emission on properties of giant dipole resonance of hot nuclei

    International Nuclear Information System (INIS)

    Wen Wanxin; Jin Genming

    2003-01-01

    The possible reasons for the discrepancy between calculation results based on the statistical evaporation model and experimental data of giant dipole resonance of very hot nuclei are discussed. Both of simulations with the standard CASCADE code and the code coupling complex particle emission are carried out. It is shown that the complex particle emission affects the properties of giant dipole resonance of very hot nuclei

  9. Fabrication and electromagnetic properties of flake ferrite particles based on diatomite

    International Nuclear Information System (INIS)

    Zhang Deyuan; Zhang Wenqiang; Cai Jun

    2011-01-01

    Hexagonal ferrite BaZn 1.1 Co 0.9 Fe 16 O 27 coated surfaces of diatomite flakes of low density were synthesized by a sol-gel method. The phase structures, morphologies, particle size and chemical compositions of the composites were characterized by X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectroscopy. The results show that hexagonal ferrite coated diatomite flakes can be achieved, and that the coating consisted of BaZn 1.1 Co 0.9 Fe 16 O 27 nanoparticles. The vibranting sample magnetometer results reveal that the flake ferrite particles have static magnetic properties. The complex permeability and permittivity of the composites were measured in the frequency range of 1-18 GHz. The microwave absorption properties of these ferrite particles are discussed. The results indicate that the flake ferrites have the potential to be used as a lightweight broad band microwave absorber. - Highlights: → We synthesize the flake ferrite particles using diatomite as a template. → Flake ferrite particles' coating layers are constituted by BaZn 1.1 Co 0.9 Fe 16 O 27 nanoparticles. → Flake ferrite particles have good static magnetic properties.→ Flake ferrites are a kind lightweight broad band microwave absorber.

  10. Fabrication and electromagnetic properties of flake ferrite particles based on diatomite

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang Wenqiang, E-mail: zwqzwqzwqzwq@126.com [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Cai Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China)

    2011-09-15

    Hexagonal ferrite BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} coated surfaces of diatomite flakes of low density were synthesized by a sol-gel method. The phase structures, morphologies, particle size and chemical compositions of the composites were characterized by X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectroscopy. The results show that hexagonal ferrite coated diatomite flakes can be achieved, and that the coating consisted of BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} nanoparticles. The vibranting sample magnetometer results reveal that the flake ferrite particles have static magnetic properties. The complex permeability and permittivity of the composites were measured in the frequency range of 1-18 GHz. The microwave absorption properties of these ferrite particles are discussed. The results indicate that the flake ferrites have the potential to be used as a lightweight broad band microwave absorber. - Highlights: > We synthesize the flake ferrite particles using diatomite as a template. > Flake ferrite particles' coating layers are constituted by BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} nanoparticles. > Flake ferrite particles have good static magnetic properties. > Flake ferrites are a kind lightweight broad band microwave absorber.

  11. Correlation between morphology and magnetic properties of electrochemically produced cobalt powder particles

    Directory of Open Access Journals (Sweden)

    Maksimović Vesna M.

    2015-01-01

    Full Text Available Cobalt 3D powder particles were successfully prepared by the galvanostatic electrodeposition. Electrodeposited cobalt powder were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, Energy Dispersive Spectroscopy (EDS analysis and SQUID magnetometry. It has been shown that morphology, structure and magnetic properties of cobalt particles are closely associated and can be easily controlled by adjusting process parameters of electrodeposition. Morphology of cobalt powder particles is strongly affected by hydrogen evolution reaction as a parallel reaction to cobalt electrodeposition. Depending on the applied current density, the two types of powder particles were formed: dendrites at lower and spongy-like particles at higher current densities. Morphologies and structures of powder particles are correlated with their magnetic properties, and compared with those of the bulk cobalt. In comparison with the properties of bulk cobalt, the obtained 3D structures exhibited a decreased saturation magnetization (MS, but an enhanced coercivity (HC which is explained by their peculiar morphology. [Projekat Ministarstva nauke Republike Srbije, br. III 45012

  12. Effect of particle size on microstructure and mechanical properties of composites produced by ARB process

    Energy Technology Data Exchange (ETDEWEB)

    Jamaati, Roohollah, E-mail: r.jamaatikenari@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Amirkhanlou, Sajjad; Toroghinejad, Mohammad Reza; Niroumand, Behzad [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2011-02-25

    Research highlights: {yields} Microstructure of MMC with larger particles becomes completely uniform, sooner. {yields} When the number of cycles increased, tensile strength for both samples improved. {yields} Up to the seventh cycle, tensile strength of MMC with larger particles was bigger. {yields} First, the tensile elongation of MMCs was decreased, and then it was improved. - Abstract: In the present work, Al/10 vol.% SiC metal matrix composite (MMC) was manufactured by accumulative roll bonding (ARB) process. The silicon carbide particles with two various particle sizes of 40 and 2 {mu}m were used. Effect of particle size on microstructure (by scanning electron microscopy) and mechanical properties (tensile strength and elongation) at various ARB cycles was investigated. It was found that the microstructural evolution in MMC with 40 {mu}m particle size was more salient compared to the MMCs with 2 {mu}m particle size. Also, the composite strip with 40 {mu}m particle size became uniform with high bonding quality and without any porosity sooner than the strip of 2 {mu}m particle size. Moreover, when the number of cycles was increased, the tensile strength for both samples was improved. The tensile strength of the composite strip with 40 {mu}m particle size was more than the composite strip with 2 {mu}m up to the seventh cycle. By increasing the number of cycles after the seventh cycle, the value of tensile strength of MMC with 40 {mu}m particle size became saturated and then decreased, and its tensile strength became less than that of the composite with 2 {mu}m particle size for the ninth and eleventh cycles. Up to the seventh cycle, when the number of ARB cycles was increased, the elongation of composite strips was decreased, but after the ninth cycle, the tensile elongation for both samples was improved.

  13. Effect of particle size on microstructure and mechanical properties of composites produced by ARB process

    International Nuclear Information System (INIS)

    Jamaati, Roohollah; Amirkhanlou, Sajjad; Toroghinejad, Mohammad Reza; Niroumand, Behzad

    2011-01-01

    Research highlights: → Microstructure of MMC with larger particles becomes completely uniform, sooner. → When the number of cycles increased, tensile strength for both samples improved. → Up to the seventh cycle, tensile strength of MMC with larger particles was bigger. → First, the tensile elongation of MMCs was decreased, and then it was improved. - Abstract: In the present work, Al/10 vol.% SiC metal matrix composite (MMC) was manufactured by accumulative roll bonding (ARB) process. The silicon carbide particles with two various particle sizes of 40 and 2 μm were used. Effect of particle size on microstructure (by scanning electron microscopy) and mechanical properties (tensile strength and elongation) at various ARB cycles was investigated. It was found that the microstructural evolution in MMC with 40 μm particle size was more salient compared to the MMCs with 2 μm particle size. Also, the composite strip with 40 μm particle size became uniform with high bonding quality and without any porosity sooner than the strip of 2 μm particle size. Moreover, when the number of cycles was increased, the tensile strength for both samples was improved. The tensile strength of the composite strip with 40 μm particle size was more than the composite strip with 2 μm up to the seventh cycle. By increasing the number of cycles after the seventh cycle, the value of tensile strength of MMC with 40 μm particle size became saturated and then decreased, and its tensile strength became less than that of the composite with 2 μm particle size for the ninth and eleventh cycles. Up to the seventh cycle, when the number of ARB cycles was increased, the elongation of composite strips was decreased, but after the ninth cycle, the tensile elongation for both samples was improved.

  14. Effects of fuel components and combustion particle physicochemical properties on toxicological responses of lung cells.

    Science.gov (United States)

    Jaramillo, Isabel C; Sturrock, Anne; Ghiassi, Hossein; Woller, Diana J; Deering-Rice, Cassandra E; Lighty, JoAnn S; Paine, Robert; Reilly, Christopher; Kelly, Kerry E

    2018-03-21

    The physicochemical properties of combustion particles that promote lung toxicity are not fully understood, hindered by the fact that combustion particles vary based on the fuel and combustion conditions. Real-world combustion-particle properties also continually change as new fuels are implemented, engines age, and engine technologies evolve. This work used laboratory-generated particles produced under controlled combustion conditions in an effort to understand the relationship between different particle properties and the activation of established toxicological outcomes in human lung cells (H441 and THP-1). Particles were generated from controlled combustion of two simple biofuel/diesel surrogates (methyl decanoate and dodecane/biofuel-blended diesel (BD), and butanol and dodecane/alcohol-blended diesel (AD)) and compared to a widely studied reference diesel (RD) particle (NIST SRM2975/RD). BD, AD, and RD particles exhibited differences in size, surface area, extractable chemical mass, and the content of individual polycyclic aromatic hydrocarbons (PAHs). Some of these differences were directly associated with different effects on biological responses. BD particles had the greatest surface area, amount of extractable material, and oxidizing potential. These particles and extracts induced cytochrome P450 1A1 and 1B1 enzyme mRNA in lung cells. AD particles and extracts had the greatest total PAH content and also caused CYP1A1 and 1B1 mRNA induction. The RD extract contained the highest relative concentration of 2-ring PAHs and stimulated the greatest level of interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNFα) cytokine secretion. Finally, AD and RD were more potent activators of TRPA1 than BD, and while neither the TRPA1 antagonist HC-030031 nor the antioxidant N-acetylcysteine (NAC) affected CYP1A1 or 1B1 mRNA induction, both inhibitors reduced IL-8 secretion and mRNA induction. These results highlight that differences in fuel and combustion conditions

  15. Improved ice particle optical property simulations in the ultraviolet to far-infrared regime

    International Nuclear Information System (INIS)

    Bi, Lei; Yang, Ping

    2017-01-01

    To derive the bulk radiative properties of ice clouds, aircraft contrails and snow grains, which are fundamental to atmospheric radiative transfer calculations in downstream applications, it is necessary to accurately simulate the scattering of light by individual ice particles. An ice particle optical property database reported in 2013 (hereafter, TAMUice2013) is updated (hereafter, TAMUice2016) to incorporate recent advances in computation of the optical properties of nonspherical particles. Specifically, we employ the invariant imbedding T-matrix (II-TM) method to compute the optical properties of particles with small to moderate size parameters. Both versions use the Improved Geometric Optics Method (IGOM) to compute the optical properties of large ice crystals, but TAMUice2016 improves the treatment of inhomogeneous waves inside the scattering particles in the case where ice is absorptive such as at infrared wavelengths. To bridge the gap between the extinction efficiencies computed from the II-TM and the IGOM, TAMUice2016 includes spectrally dependent higher order terms of the edge effect in addition to the first order counterpart considered in TAMUice2013. Furthermore, the differences between TAMUice2013 and TAMUice2016 are quantified with respect to the computation of the bulk optical properties of ice clouds. - Highlights: • A previous database of the single-scattering properties of ice crystals is improved. • A combination of the invariant imbedding T-matrix and improved geometric optics methods is used. • The treatment of inhomogeneous waves in an absorptive ice crystal is improved. • Higher order terms of the edge effect are considered in the updated database.

  16. Laboratory Studies of the Optical Properties and Condensation Processes of Cosmic Dust Particles

    Science.gov (United States)

    Abbas, Mian M.; Craven, Paul D.; Spann, James F.; Tankosic, Dragana; Six, N. Frank (Technical Monitor)

    2002-01-01

    A laboratory facility for levitating single isolated dust particles in an electrodynamics balance has been developing at NASA/Marshall Space Flight Center for conducting a variety of experimental, of astrophysical interest. The objective of this research is to employ this innovative experimental technique for studies of the physical and optical properties of the analogs of cosmic grains of 0.2-10 micron size in a chamber with controlled pressure/temperatures simulating astrophysical environments. In particular, we will carry out three classes of experiments to investigate the microphysics of the analogs of interstellar and interplanetary dust grains. (1) Charge characteristics of micron size single dust grains to determine the photoelectric efficiencies, yields, and equilibrium potentials when exposed to UV radiation. These measurements will provide the much-needed photoelectric emission data relating to individual particles as opposed to that for the bulk materials available so far. (2) Infrared optical properties of dust particles obtained by irradiating the particles with radiation from tunable infrared diode lasers and measuring the scattered radiation. Specifically, the complex refractive indices, the extinction coefficients, the scattering phase functions, and the polarization properties of single dust grains of interest in interstellar environments, in the 1-25 micron spectral region will be determined. (3) Condensation experiments to investigate the deposition of volatile gases on colder nucleated particles in dense interstellar clouds and lower planetary atmospheres. The increase in the mass or m/q ratio due to condensation on the particle will be monitored as a function of the dust particle temperature and the partial pressure of the injected volatile gas. The measured data wild permit determination of the sticking efficiencies of volatile gases of astrophysical interest. Preliminary results based on photoelectric emission experiments on 0.2-6.6 micron

  17. Physical properties of elongated magnetic particles: magnetization and friction coefficient anisotropies.

    Science.gov (United States)

    Vereda, Fernando; de Vicente, Juan; Hidalgo-Alvarez, Roque

    2009-06-02

    Anisotropy counts: A brief review of the main physical properties of elongated magnetic particles (EMPs) is presented. The most important characteristic of an EMP is the additional contribution of shape anisotropy to the total anisotropy energy of the particle, when compared to spherical magnetic particles. The electron micrograph shows Ni-ferrite microrods fabricated by the authors.We present an overview of the main physical properties of elongated magnetic particles (EMPs), including some of their more relevant properties in suspension. When compared to a spherical magnetic particle, the most important characteristic of an EMP is an additional contribution of shape anisotropy to the total anisotropy energy of the particle. Increasing aspect ratios also lead to an increase in both the critical single-domain size of a magnetic particle and its resistance to thermally activated spontaneous reversal of the magnetization. For single-domain EMPs, magnetization reversal occurs primarily by one of two modes, coherent rotation or curling, the latter being facilitated by larger aspect ratios. When EMPs are used to prepare colloidal suspensions, other physical properties come into play, such as their anisotropic friction coefficient and the consequent enhanced torque they experience in a shear flow, their tendency to align in the direction of an external field, to form less dense sediments and to entangle into more intricate aggregates. From a more practical point of view, EMPs are discussed in connection with two interesting types of magnetic colloids: magnetorheological fluids and suspensions for magnetic hyperthermia. Advances reported in the literature regarding the use of EMPs in these two systems are included. In the final section, we present a summary of the most relevant methods documented in the literature for the fabrication of EMPs, together with a list of the most common ferromagnetic materials that have been synthesized in the form of EMPs.

  18. Ultrafine particles in concrete: Influence of ultrafine particles on concrete properties and application to concrete mix design

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, Carsten

    2010-07-01

    In this work, the influence of ultrafine particles on concrete properties was investigated. In the context of this work, ultrafine particles (reactive and inert materials) are particles finer than cement. Due to the development of effective superplasticizers, the incorporation of ultrafine particles in concrete is nowadays possible. Different minerals, usually considered inert, were tested. These minerals were also used in combination with reactive silica fume. The modified Andreassen model was used to optimise the particle size distribution and thus the packing density of the complete mix composition. Heat of hydration, compressive strength, shrinkage, frost resistance and the microstructure were investigated.The influence of different ultrafine inert materials on the cement hydration was investigated. The results show that most of the minerals have an accelerating effect. They provide nucleation sites for hydration products and contribute in that way to a faster dissolution of cement grains. Minerals containing calcium were found to influence the early stage of hydration as well. These minerals shortened the dormant period of the cement hydration, the effect is known from limestone filler in self-compacting concrete. In a first test series on concrete, different ultrafine inert particles were used to replace cement. That was done in several ways; with constant water content or constant w/c. The results from this test series show that the best effect is achieved when cement is replaced by suitable ultrafines while the w/c is kept constant. In doing so, the compressive strength can be increased and shrinkage can be reduced. The microstructure is improved and becomes denser with improved packing at microlevel. Efficiency factors (k values) for the ultrafine inert materials were calculated from the compressive strength results. The k values are strongly dependent on the mode of cement replacement, fineness and type of the replacement material and curing time. Drying

  19. Laboratory studies of the growth, sublimation, and light- scattering properties of single levitated ice particles

    Science.gov (United States)

    Bacon, Neil Julian

    2001-12-01

    I describe experiments to investigate the properties of microscopic ice particles. The goal of the work was to measure parameters that are important in cloud processes and radiative transfer, using a novel technique that avoids the use of substrates. The experiments were conducted in two separate electrodynamic balance chambers. Single, charged ice particles were formed from frost particles or from droplets frozen either homogeneously or heteroge neously with a bionucleant. The particles were trapped at temperatures between -38°C and -4°C and grown or sublimated according to the temperature gradient in the cham ber. I describe observations of breakup of sublimating frost particles, measurements of light scattering by hexagonal crystals, and observations of the morphology of ice particles grown from frozen water droplets and frost particles. The breaking strength of frost particles was an order of magnitude less than that of bulk ice. Light scattering features not previously observed were analyzed and related to crystal dimension. Initial results from a computer model failed to reproduce these features. The widths of scattering peaks suggest that surface roughness may play a role in determining the angular distribution of scattered light. Ice particle mass evolution was found to be consistent with diffusion- limited growth. Crystals grown slowly from frozen droplets adopted isometric habits, while faster growth resulted in thin side-planes, although there was not an exact correspondence between growth conditions and particle morphology. From the morphological transition, I infer lower limits for the critical supersaturation for layer nucleation on the prism face of 2.4% at -15°C, 4.4% at -20°C, and 3.1% at -25°C. Analytic expressions for the size dependence of facet stability are developed, indicating a strong dependence of stability on both crystal size and surface kinetics, and compared with data. I discuss the role of complex particle morphologies in

  20. Inherent optical properties of pollen particles: a case study for the morning glory pollen.

    Science.gov (United States)

    Liu, Chao; Yin, Yan

    2016-01-25

    Biological aerosols, such as bacteria, fungal spores, and pollens, play an important role on various atmospheric processes, whereas their inherent optical property is one of the most uncertainties that limit our ability to assess their effects on weather and climate. A numerical model with core-shell structure, hexagonal grids and barbs is developed to represent one kind of realistic pollen particles, and their inherent optical properties are simulated using a pseudo-spectral time domain method. Both the hexagonal grids and barbs substantially affect the modeled pollen optical properties. Results based on the realistic particle model are compared with two equivalent spherical approximations, and the significant differences indicate the importance of considering pollen geometries for their optical properties.

  1. Effect of photochemical ageing on the ice nucleation properties of diesel and wood burning particles

    Directory of Open Access Journals (Sweden)

    C. Chou

    2013-01-01

    Full Text Available A measurement campaign (IMBALANCE conducted in 2009 was aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro without emission aftertreatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC at three nominal temperatures, −30 °C, −35 °C and −40 °C. Freshly emitted diesel particles showed ice formation only at −40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi and 92% relative humidity with respect to water (RHw, and photochemical ageing did not play a role in modifying their ice nucleation behaviour. Only one diesel experiment where α-pinene was added for the ageing process, showed an ice nucleation enhancement at −35 °C. Wood burning particles also act as ice nuclei (IN at −40 °C in the deposition mode at the same conditions as for diesel particles and photochemical ageing also did not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at −35 °C whereas no ice nucleation was observed at −30 °C. Photochemical ageing did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below −40 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical ageing on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

  2. Field measurements of hygroscopic properties and state of mixing of nucleation mode particles

    Directory of Open Access Journals (Sweden)

    M. Väkevä

    2002-01-01

    Full Text Available An Ultrafine Tandem Differential Mobility Analyser (UF-TDMA has been used in several field campaigns over the last few years. The investigations were focused on the origin and properties of nucleation event aerosols, which are observed frequently in various environments. This paper gives a summary of the results of 10 nm and 20 nm particle hygroscopic properties from different measurement sites: an urban site, an urban background site and a forest site in Finland and a coastal site in western Ireland. The data can be classified in four hygroscopic growth classes: hydrofobic, less-hygroscopic, more-hygroscopic and sea-salt. Similar classification has been earlier presented for Aitken and accumulation mode particles. In urban air, the summertime 10 nm particles showed varying less-hygroscopic growth behaviour, while winter time 10 nm and 20 nm particles were externally mixed with two different hygroscopic growth modes. The forest measurements revealed diurnal behaviour of hygroscopic growth, with high growth factors at day time and lower during night. The urban background particles had growth behaviour similar to the urban and forest measurement sites depending on the origin of the observed particles. The coastal measurements were strongly affected by air mass history. Both 10 nm and 20 nm particles were hygroscopic in marine background air. The 10 nm particles produced during clean nucleation burst periods were hydrofobic. Diurnal variation and higher growth factors of 10 nm particles were observed in air affected by other source regions. External mixing was occasionally observed at all the sites, but incidents with more than two growth modes were extremely rare.

  3. Physico-chemical properties and biological effects of diesel and biomass particles

    KAUST Repository

    Longhin, Eleonora

    2016-05-15

    © 2016 Elsevier Ltd. Diesel combustion and solid biomass burning are the major sources of ultrafine particles (UFP) in urbanized areas. Cardiovascular and pulmonary diseases, including lung cancer, are possible outcomes of combustion particles exposure, but differences in particles properties seem to influence their biological effects.Here the physico-chemical properties and biological effects of diesel and biomass particles, produced under controlled laboratory conditions, have been characterized. Diesel UFP were sampled from a Euro 4 light duty vehicle without DPF fuelled by commercial diesel and run over a chassis dyno. Biomass UFP were collected from a modern automatic 25 kW boiler propelled by prime quality spruce pellet. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of both diesel and biomass samples showed aggregates of soot particles, but in biomass samples ash particles were also present. Chemical characterization showed that metals and PAHs total content was higher in diesel samples compared to biomass ones.Human bronchial epithelial (HBEC3) cells were exposed to particles for up to 2 weeks. Changes in the expression of genes involved in xenobiotic metabolism were observed after exposure to both UFP already after 24 h. However, only diesel particles modulated the expression of genes involved in inflammation, oxidative stress and epithelial-to-mesenchymal transition (EMT), increased the release of inflammatory mediators and caused phenotypical alterations, mostly after two weeks of exposure.These results show that diesel UFP affected cellular processes involved in lung and cardiovascular diseases and cancer. Biomass particles exerted low biological activity compared to diesel UFP. This evidence emphasizes that the study of different emission sources contribution to ambient PM toxicity may have a fundamental role in the development of more effective strategies for air quality improvement.

  4. Scaling Properties of Particle Density Fields Formed in Simulated Turbulent Flows

    Science.gov (United States)

    Hogan, Robert C.; Cuzzi, Jeffrey N.; Dobrovolskis, Anthony R.; DeVincenzi, Donald (Technical Monitor)

    1998-01-01

    inertial-range energy dissipation fields of experimental turbulent flows at Re(sub lambda) = 110 and 1100. Based on this agreement, and the expectation that both dissipation and particle concentration are controlled by the same cascade process, we hypothesize that singularity spectra similar to the ones found in this work provide a good characterization of the spatially averaged statistical properties of preferentially concentrated particles in higher Re(sub lambda) turbulent flows.

  5. Microstructure and wear properties of the electroslag remelting layer reinforced by TiC particles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The electroslag remelting (ESR) layer reinforced by TiC particles was obtained by electroslag remelting.The microstructure and wear properties of the ESR layer were studied by means of scanning electron microscopy (SEM),X-ray diffraction (XRD),and wear test.The results indicate that TiC particles are synthesized by self-propagating high-temperature synthesis (SHS) reaction during the electroslag remelting process.The size of TiC particles is in the range of 1-10 μm,and the distribution of TiC particles is uniform,from outside to inside of the ESR layer,and the volume fraction and the size of TiC particles decrease gradually.Molten iron and slag flow into porosity due to the SHS process leading to rapid densification and the elimination of porosity in the ESR layer during the ESR process.TiC particles enhance the wear resistance of the ESR layer,whereas CaF2 can improve the high temperature lubricating property of the ESR layer.

  6. Effect of the carbonyl iron particles on acoustic absorption properties of magnetic polyurethane foam

    Science.gov (United States)

    Geng, Jialu; Wang, Caiping; Zhu, Honglang; Wang, Xiaojie

    2018-03-01

    Elastomeric matrix embedded with magnetic micro-sized particles has magnetically controllable properties, which has been investigated extensively in the last decades. In this study we develop a new magnetically controllable elastomeric material for acoustic applications at lower frequencies. The soft polyurethane foam is used as matrix material due to its extraordinary elastic and acoustic absorption properties. One-step method is used to synthesize polyurethane foam, in which all components including polyether polyols 330N, MDI, deionized water, silicone oil, carbonyl iron particle (CIP) and catalyst are put into one container for curing. Changing any component can induce the change of polyurethane foam's properties, such as physical and acoustic properties. The effect of the content of MDI on acoustic absorption is studied. The CIPs are aligned under extra magnetic field during the foaming process. And the property of polyurethane foam with aligned CIPs is also investigated. Scanning electron microscope (SEM) is used to observe the structure of pore and particle-chain. The two-microphone impedance tube and the transfer function method are used to test acoustic absorption property of the magnetic foams.

  7. The single- and double-particle properties and the current reversal of coupled Brownian motors

    International Nuclear Information System (INIS)

    Li, Chen-Pu; Chen, Hong-Bin; Zheng, Zhi-Gang; Fan, Hong; Shen, Wen-Mei

    2017-01-01

    In this paper, we investigate the directed transport of coupled Brownian motors composed of two identical particles which is individually subject to a time-symmetric rocking force in spatially-symmetric periodic potentials. We find that both the coupling free length and the coupling strength can induce the reversed motion of the coupled Brownian motors, the essence of which is the coupled Brownian motors can exhibit completely different single- or double-particle properties under certain conditions. Namely, the current reversal is the result of the mutual conversion between the single- and double-particle properties of the coupled Brownian motors. Moreover, the directed current of coupled Brownian motors can be optimized and manipulated by adjusting the strength, the period, the phase difference of the rocking forces, and the noise intensity. (paper)

  8. Highly temperature responsive core-shell magnetic particles: synthesis, characterization and colloidal properties.

    Science.gov (United States)

    Rahman, Md Mahbubor; Chehimi, Mohamed M; Fessi, Hatem; Elaissari, Abdelhamid

    2011-08-15

    Temperature responsive magnetic polymer submicron particles were prepared by two step seed emulsion polymerization process. First, magnetic seed polymer particles were obtained by emulsion polymerization of styrene using potassium persulfate (KPS) as an initiator and divinylbenzne (DVB) as a cross-linker in the presence of oil-in-water magnetic emulsion (organic ferrofluid droplets). Thereafter, DVB cross-linked magnetic polymer particles were used as seed in the precipitation polymerization of N-isopropylacrylamide (NIPAM) to induce thermosensitive PNIPAM shell onto the hydrophobic polymer surface of the cross-linked magnetic polymer particles. To impart cationic functional groups in the thermosensitive PNIPAM backbone, the functional monomer aminoethylmethacrylate hydrochloride (AEMH) was used to polymerize with NIPAM while N,N'-methylenebisacrylamide (MBA) and 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (V-50) were used as a cross-linker and as an initiator respectively. The effect of seed to monomer (w/w) ratio along with seed nature on the final particle morphology was investigated. Dynamic light scattering (DLS) results demonstrated particles swelling at below volume phase transition temperature (VPTT) and deswelling above the VPTT. The perfect core (magnetic) shell (polymer) structure of the particles prepared was confirmed by Transmission Electron Microscopy (TEM). The chemical composition of the particles were determined by thermogravimetric analysis (TGA). The effect of temperature, pH, ionic strength on the colloidal properties such as size and zeta potential of the micron sized thermo-sensitive magnetic particles were also studied. In addition, a short mechanistic discussion on the formation of core-shell morphology of magnetic polymer particles has also been discussed. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Properties of potential eco-friendly gas replacements for particle detectors in high-energy physics

    Science.gov (United States)

    Saviano, G.; Ferrini, M.; Benussi, L.; Bianco, S.; Piccolo, D.; Colafranceschi, S.; KjØlbro, J.; Sharma, A.; Yang, D.; Chen, G.; Ban, Y.; Li, Q.; Grassini, S.; Parvis, M.

    2018-03-01

    Gas detectors for elementary particles require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. This work studies properties of potential eco-friendly gas replacements by computing the physical and chemical parameters relevant for use as detector media, and suggests candidates to be considered for experimental investigation.

  10. Green's functions for theories with massless particles (in perturbation theory). [Growth properties, momentum space, mass renormalization

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, P [European Organization for Nuclear Research, Geneva (Switzerland); Seneor, R [European Organization for Nuclear Research, Geneva (Switzerland); Ecole Polytechnique, 75 - Paris (France). Centre de Physique Theorique)

    1975-01-01

    With the method of perturbative renormalization developed by Epstein and Glaser it is shown that Green's functions exist for theories with massless particles such as Q.E.D. and lambda:PHI/sup 2n/ theories. Growth properties are given in momentum space. In the case of Q.E.D., it is also shown that one can perform the physical mass renormalization.

  11. Plastic tube hadron calorimeter: study of operation properties and particle separation

    International Nuclear Information System (INIS)

    Akopdzhanov, G.A.; Belousov, V.I.; Blik, A.M.; Romanovski, V.I.

    1988-01-01

    The DELPHI hadron calorimeter prototype plastic tubes were tested to show a long-term stability of the prototype operating with the gas mixture carbon dioxide isobutane. The operating properties of the prototype are investigated and presented as well as the results on particles separation. 5 refs.; 11 figs.; 9 tabs

  12. Graphene oxide-modified ZnO particles: synthesis, characterization, and antibacterial properties

    Directory of Open Access Journals (Sweden)

    Zhong LL

    2015-08-01

    Full Text Available Linlin Zhong, Kyusik Yun Department of Bionanotechnology, Gachon University, Gyeonggi-do, Republic of Korea Abstract: Nanosized ZnO particles with diameters of 15 nm were prepared with a solution precipitation method at low cost and high yield. The synthesis of the particles was functionalized by the organic solvent dimethylformamide, and the particles were covalently bonded to the surface of graphene oxide. The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy. Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the physical and chemical properties of the ZnO/graphene oxide composites that differed from those of the individual components. Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV. Excellent antibacterial activity of ZnO/graphene oxide composites was observed with a microdilution method in which minimum inhibitory concentrations of 6.25 µg/mL for Escherichia coli and Salmonella typhimurium, 12.5 µg/mL for Bacillus subtilis, and 25 µg/mL for Enterococcus faecalis. After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties. Keywords: graphene oxide, ZnO, characterization, antibacterial property

  13. The anomalous physical and chemical properties of gold nano-particles

    International Nuclear Information System (INIS)

    Cortie, M.B.

    2003-01-01

    Full text: Although gold is the most inert of all metallic elements, it has been discovered during the last two decades that it has interesting properties as a nano-particle. Some of the properties of interest include its activity as a heterogeneous catalyst, particularly at low temperatures, its optical properties, and the tendency of its nano-particles to adopt non-crystallographic structures. There are a number of curious aspects to catalysis by gold that are attracting academic and industrial investigation and much is still not understood about the mechanism by which they work. For example, apparently similar preparation techniques result in activities of hugely varying magnitude. In the present talk I assess the what is known about gold nano-particles, with particular reference to their physical, electronic, crystallographic and catalytic properties. It is shown that there is much evidence in favour of the belief that it is the unique electronic structure of these particles that imbues them with catalytic activity. If this is true then tighter control of the electronic structure would allow for the design of more specific and more active catalysts

  14. Improvements in mechanical properties in SiC by the addition of TiC particles

    International Nuclear Information System (INIS)

    Wei, G.C.; Becher, P.F.

    1984-01-01

    Silicon carbide ceramics containing up to 24.6 vol% dispersed TiC particles yielded fully dense composites by hot-pressing at 2000 0 C with 1 wt% Al and 1 wt% C added. The microstructure consists of fine TiC particles in a fine-grained SiC matrix. Addition of TiC particles increases the critical fracture toughness of SiC (to approx. =6 MPa /SUP ./ m /SUP 1/2/ at 24.6 vol% TiC) and yields high flexure strength (greater than or equal to 680 MPa), with both properties increasing with increasing volume fraction of TiC. The strengths at high temperatures are also improved by the TiC additions. Observations of the fracture path indicate that the improved toughness and strength are a result of crack deflection by the TiC particles

  15. A study on coated particle fuel properties and performances and phase-I data base establishment

    International Nuclear Information System (INIS)

    Kim, Yong Soo; Lee, Hyo Cheol; Im, Byeong Ju; Yun, Sang Pil; Son, Seung Beom; Lee, Gyeong Hui; Jang, Jeong Nam

    2006-03-01

    For the successful development of the high temperature gas cooled reactor acquisition and generation of the high temperature properties of reactor materials, especially temperature and burn-up dependent properties of coated particle fuel and fuel element, are crucially essential. Recently national project for HTGR for hydrogen production has been kicked off. However, we have had little experience on this new challenges. Therefore, it became necessary to build up the materials properties and fuel performance data base. In this study, a primitive properties and performance DB for coated particle fuel was developed. This database report consists two sections: materials properties and fuel performance. The materials properties has three parts: kernel materials, carbide coating materials, and fuel elements and graphite matrix. UO 2 and UCO belong to kernel materials while PyC, SiC, and ZrC comprises the coating materials section. Thermal, mechanical and physical properties of these materials were collected, reviewed, and summarized. Additionally, the property change induced by manufacture process and irradiation were collected and summarized. Performance data were also collected, reviewed, and analyzed based on the key phenomena and failure mechanism. All of these data will be accessible in the on-line system. These results will be directly used for HTGR fuel design and fabrication and preliminary fuel performance analysis under irradiation

  16. Biological properties of purified recombinant HCV particles with an epitope-tagged envelope

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hitoshi; Akazawa, Daisuke [Department of Virology II, National Institute of Infectious Diseases, Tokyo (Japan); Toray Industries, Inc., Kanagawa (Japan); Kato, Takanobu; Date, Tomoko [Department of Virology II, National Institute of Infectious Diseases, Tokyo (Japan); Shirakura, Masayuki [Department of Virology II, National Institute of Infectious Diseases, Tokyo (Japan); Toray Industries, Inc., Kanagawa (Japan); Nakamura, Noriko; Mochizuki, Hidenori [Toray Industries, Inc., Kanagawa (Japan); Tanaka-Kaneko, Keiko; Sata, Tetsutaro [Department of Pathology, National Institute of Infectious Diseases, Tokyo (Japan); Tanaka, Yasuhito [Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medicine, Nagoya (Japan); Mizokami, Masashi [Research Center for Hepatitis and Immunology, Kohnodai Hospital, International Medical Center of Japan, Chiba (Japan); Suzuki, Tetsuro [Department of Virology II, National Institute of Infectious Diseases, Tokyo (Japan); Wakita, Takaji, E-mail: wakita@nih.go.jp [Department of Virology II, National Institute of Infectious Diseases, Tokyo (Japan)

    2010-05-14

    To establish a simple system for purification of recombinant infectious hepatitis C virus (HCV) particles, we designed a chimeric J6/JFH-1 virus with a FLAG (FL)-epitope-tagged sequence at the N-terminal region of the E2 hypervariable region-1 (HVR1) gene (J6/JFH-1/1FL). We found that introduction of an adaptive mutation at the potential N-glycosylation site (E2N151K) leads to efficient production of the chimeric virus. This finding suggests the involvement of glycosylation at Asn within the envelope protein(s) in HCV morphogenesis. To further analyze the biological properties of the purified recombinant HCV particles, we developed a strategy for large-scale production and purification of recombinant J6/JFH-1/1FL/E2N151K. Infectious particles were purified from the culture medium of J6/JFH-1/1FL/E2N151K-infected Huh-7 cells using anti-FLAG affinity chromatography in combination with ultrafiltration. Electron microscopy of the purified particles using negative staining showed spherical particle structures with a diameter of 40-60 nm and spike-like projections. Purified HCV particle-immunization induced both an anti-E2 and an anti-FLAG antibody response in immunized mice. This strategy may contribute to future detailed analysis of HCV particle structure and to HCV vaccine development.

  17. Dependence of the microstructural properties of ZnO particles on their synthesis

    International Nuclear Information System (INIS)

    Music, Svetozar; Saric, Ankica; Popovic, Stanko

    2008-01-01

    The influence of experimental conditions on the precipitation of ZnO particles and their microstructural properties has been investigated using X-ray powder diffraction, Fourier transform infrared spectroscopy and thermal field emission scanning electron microscopy. Mixing of ZnCl 2 or Zn(ac) 2 solution with Na 2 CO 3 solution of proper concentrations yielded aggregates of fine Zn 5 (CO 3 ) 2 (OH) 6 particles, which were converted to nanosize ZnO particles at 300 deg. C. The size of these ZnO particles increased to around 100 nm upon heating at 600 deg. C, whereas a small fraction of them turned out in the form of aggregates. The obtained ZnO particles assumed a pseudospherical shape; however, their basic structure was based on the hexagonal space group. Precipitation of Zn 2+ ions in decomposing HMTA at 90 deg. C yielded ZnO particles around micron range. Crystalline Zn(OH) 2 was not detected in the precipitates. ZnO particles obtained by this method were strongly elongated in the direction of the crystallographic c-axis

  18. Biological properties of purified recombinant HCV particles with an epitope-tagged envelope

    International Nuclear Information System (INIS)

    Takahashi, Hitoshi; Akazawa, Daisuke; Kato, Takanobu; Date, Tomoko; Shirakura, Masayuki; Nakamura, Noriko; Mochizuki, Hidenori; Tanaka-Kaneko, Keiko; Sata, Tetsutaro; Tanaka, Yasuhito; Mizokami, Masashi; Suzuki, Tetsuro; Wakita, Takaji

    2010-01-01

    To establish a simple system for purification of recombinant infectious hepatitis C virus (HCV) particles, we designed a chimeric J6/JFH-1 virus with a FLAG (FL)-epitope-tagged sequence at the N-terminal region of the E2 hypervariable region-1 (HVR1) gene (J6/JFH-1/1FL). We found that introduction of an adaptive mutation at the potential N-glycosylation site (E2N151K) leads to efficient production of the chimeric virus. This finding suggests the involvement of glycosylation at Asn within the envelope protein(s) in HCV morphogenesis. To further analyze the biological properties of the purified recombinant HCV particles, we developed a strategy for large-scale production and purification of recombinant J6/JFH-1/1FL/E2N151K. Infectious particles were purified from the culture medium of J6/JFH-1/1FL/E2N151K-infected Huh-7 cells using anti-FLAG affinity chromatography in combination with ultrafiltration. Electron microscopy of the purified particles using negative staining showed spherical particle structures with a diameter of 40-60 nm and spike-like projections. Purified HCV particle-immunization induced both an anti-E2 and an anti-FLAG antibody response in immunized mice. This strategy may contribute to future detailed analysis of HCV particle structure and to HCV vaccine development.

  19. Probing the micro-rheological properties of aerosol particles using optical tweezers

    International Nuclear Information System (INIS)

    Power, Rory M; Reid, Jonathan P

    2014-01-01

    The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques. Direct measurements of the viscosity of the particle bulk are derived from the damped oscillations in shape following coalescence of two particles, a consequence of the interplay between viscous and surface forces and the capillary driven relaxation of the approximately spheroidal composite particle. Holographic optical tweezers provide a facile method for the manipulation of arrays of particles allowing coalescence to be controllably induced between two micron-sized aerosol particles. The optical forces, while sufficiently strong to confine the composite particle, are several orders of magnitude weaker than the capillary forces driving relaxation. Light, elastically back-scattered by the particle, is recorded with sub-100 ns resolution allowing measurements of fast relaxation (low viscosity) dynamics, while the brightfield image can be used to monitor the shape relaxation extending to times in excess of 1000 s. For the slowest relaxation dynamics studied (particles with the highest viscosity) the presence and line shape of whispering gallery modes in the cavity enhanced Raman spectrum can be used to infer the relaxation time while serving the dual purpose of allowing the droplet size and refractive index to be measured with accuracies of ±0.025% and ±0.1%, respectively. The time constant for the damped relaxation can be used to infer the bulk viscosity, spanning from the dilute solution limit to a value approaching that of a glass, typically considered to be >10 12

  20. Probing the micro-rheological properties of aerosol particles using optical tweezers

    Science.gov (United States)

    Power, Rory M.; Reid, Jonathan P.

    2014-07-01

    The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques. Direct measurements of the viscosity of the particle bulk are derived from the damped oscillations in shape following coalescence of two particles, a consequence of the interplay between viscous and surface forces and the capillary driven relaxation of the approximately spheroidal composite particle. Holographic optical tweezers provide a facile method for the manipulation of arrays of particles allowing coalescence to be controllably induced between two micron-sized aerosol particles. The optical forces, while sufficiently strong to confine the composite particle, are several orders of magnitude weaker than the capillary forces driving relaxation. Light, elastically back-scattered by the particle, is recorded with sub-100 ns resolution allowing measurements of fast relaxation (low viscosity) dynamics, while the brightfield image can be used to monitor the shape relaxation extending to times in excess of 1000 s. For the slowest relaxation dynamics studied (particles with the highest viscosity) the presence and line shape of whispering gallery modes in the cavity enhanced Raman spectrum can be used to infer the relaxation time while serving the dual purpose of allowing the droplet size and refractive index to be measured with accuracies of ±0.025% and ±0.1%, respectively. The time constant for the damped relaxation can be used to infer the bulk viscosity, spanning from the dilute solution limit to a value approaching that of a glass, typically considered to be >1012 Pa s, whilst

  1. Waste Tire Particles and Gamma Radiation as Modifiers of the Mechanical Properties of Concrete

    Directory of Open Access Journals (Sweden)

    Eduardo Sadot Herrera-Sosa

    2014-01-01

    Full Text Available In polymer reinforced concrete, the Young’s modulus of both polymers and cement matrix is responsible for the detrimental properties of the concrete, including compressive and tensile strength, as well as stiffness. A novel methodology for solving such problems is based on use of ionizing radiation, which has proven to be a good tool for improvement on physical and chemical properties of several materials including polymers, ceramics, and composites. In this work, particles of 0.85 mm and 2.80 mm obtained from waste tire were submitted at 250 kGy of gamma radiation in order to modify their physicochemical properties and then used as reinforcement in Portland cement concrete for improving mechanical properties. The results show diminution on mechanical properties in both kinds of concrete without (or with irradiated tire particles with respect to plain concrete. Nevertheless such diminutions (from 2 to 16% are compensated with the use of high concentration of waste tire particles (30%, which ensures that the concrete will not significantly increase the cost.

  2. The single scattering properties of the aerosol particles as aggregated spheres

    International Nuclear Information System (INIS)

    Wu, Y.; Gu, X.; Cheng, T.; Xie, D.; Yu, T.; Chen, H.; Guo, J.

    2012-01-01

    The light scattering and absorption properties of anthropogenic aerosol particles such as soot aggregates are complicated in the temporal and spatial distribution, which introduce uncertainty of radiative forcing on global climate change. In order to study the single scattering properties of anthorpogenic aerosol particles, the structures of these aerosols such as soot paticles and soot-containing mixtures with the sulfate or organic matter, are simulated using the parallel diffusion limited aggregation algorithm (DLA) based on the transmission electron microscope images (TEM). Then, the single scattering properties of randomly oriented aerosols, such as scattering matrix, single scattering albedo (SSA), and asymmetry parameter (AP), are computed using the superposition T-matrix method. The comparisons of the single scattering properties of these specific types of clusters with different morphological and chemical factors such as fractal parameters, aspect ratio, monomer radius, mixture mode and refractive index, indicate that these different impact factors can respectively generate the significant influences on the single scattering properties of these aerosols. The results show that aspect ratio of circumscribed shape has relatively small effect on single scattering properties, for both differences of SSA and AP are less than 0.1. However, mixture modes of soot clusters with larger sulfate particles have remarkably important effects on the scattering and absorption properties of aggregated spheres, and SSA of those soot-containing mixtures are increased in proportion to the ratio of larger weakly absorbing attachments. Therefore, these complex aerosols come from man made pollution cannot be neglected in the aerosol retrievals. The study of the single scattering properties on these kinds of aggregated spheres is important and helpful in remote sensing observations and atmospheric radiation balance computations.

  3. Dielectric properties of polymer-particle nanocomposites influenced by electronic nature of filler surfaces.

    Science.gov (United States)

    Siddabattuni, Sasidhar; Schuman, Thomas P; Dogan, Fatih

    2013-03-01

    The interface between the polymer and the particle has a critical role in altering the properties of a composite dielectric. Polymer-ceramic nanocomposites are promising dielectric materials for many electronic and power devices, combining the high dielectric constant of ceramic particles with the high dielectric breakdown strength of a polymer. Self-assembled monolayers of electron rich or electron poor organophosphate coupling groups were applied to affect the filler-polymer interface and investigate the role of this interface on composite behavior. The interface has potential to influence dielectric properties, in particular the leakage and breakdown resistance. The composite films synthesized from the modified filler particles dispersed into an epoxy polymer matrix were analyzed by dielectric spectroscopy, breakdown strength, and leakage current measurements. The data indicate that significant reduction in leakage currents and dielectric losses and improvement in dielectric breakdown strengths resulted when electropositive phenyl, electron-withdrawing functional groups were located at the polymer-particle interface. At a 30 vol % particle concentration, dielectric composite films yielded a maximum energy density of ~8 J·cm(-3) for TiO2-epoxy nanocomposites and ~9.5 J·cm(-3) for BaTiO3-epoxy nanocomposites.

  4. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Wallenhorst, L.M.; Loewenthal, L.; Avramidis, G.; Gerhard, C.; Militz, H.; Ohms, G.; Viöl, W.

    2017-01-01

    Highlights: • Zn/ZnO mixed systems were deposited from elemental zinc by a cold plasma-spray process. • Oxidation was confirmed by XPS. • The coatings exhibited a strong absorption in the UV spectral range, thus being suitable as protective layers, e.g. on thermosensitive materials. - Abstract: In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  5. Correlation of Optical Properties with Atmospheric Solid Organic Particles (ASOPs) in the Southern Great Plains

    Science.gov (United States)

    Bonanno, D.; Fraund, M. W.; Pham, D.; China, S.; Wang, B.; Laskin, A.; Gilles, M. K.; Moffet, R.

    2017-12-01

    The Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) Campaign was carried out to gain a better understanding of the lifecycle of shallow clouds. The HISCALE experiment was designed to contrast two seasons, wet and dry, and determine their effect on atmospheric cloud and aerosol processes. The spring component to HISCALE was selected to characterize mixing state for particles collected onto substrates. Sampling was performed to obtain airborne soil organic particles (ASOP), which are believed to be ejected following rain events. The unique composition of the ASOP have been shown to affect optical properties. The collection of particles took place at the Atmospheric Radiation Measurement Southern Great Plains (ARM SGP) field site. The Scanning Transmission X-Ray Microscope (STXM) was used to image the samples collected during the first HI-SCALE Campaign to determine the carbonaceous mixing state. Scanning Electron Microscopy Energy-dispersive X-ray (SEM/EDX) analysis is more sensitive to the inorganic makeup of particles, while STXM renders a more comprehensive analysis of the organics. Measurements such as nephelometry, Particle Soot Absorption Photometry (PSAP) from the ARM archive are correlated with microscopy measurements. The primary focus is the relation between composition and morphology of ASOP with optical properties.

  6. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Wallenhorst, L.M., E-mail: lena.wallenhorst@hawk-hhg.de [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Loewenthal, L.; Avramidis, G. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Gerhard, C. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Fraunhofer Institute for Surface Engineering and Thin Films, Application Center for Plasma and Photonics, Von-Ossietzky-Str. 100, 37085 Göttingen (Germany); Militz, H. [Wood Biology and Wood Products, Burckhardt Institute, Georg-August-University Göttingen, Büsgenweg 4, 37077 Göttingen (Germany); Ohms, G. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Viöl, W. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Fraunhofer Institute for Surface Engineering and Thin Films, Application Center for Plasma and Photonics, Von-Ossietzky-Str. 100, 37085 Göttingen (Germany)

    2017-07-15

    Highlights: • Zn/ZnO mixed systems were deposited from elemental zinc by a cold plasma-spray process. • Oxidation was confirmed by XPS. • The coatings exhibited a strong absorption in the UV spectral range, thus being suitable as protective layers, e.g. on thermosensitive materials. - Abstract: In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  7. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    Science.gov (United States)

    Wallenhorst, L. M.; Loewenthal, L.; Avramidis, G.; Gerhard, C.; Militz, H.; Ohms, G.; Viöl, W.

    2017-07-01

    In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  8. Mechanical and thermal properties of phthalonitrile resin reinforced with silicon carbide particles

    International Nuclear Information System (INIS)

    Derradji, Mehdi; Ramdani, Noureddine; Zhang, Tong; Wang, Jun; Feng, Tian-tian; Wang, Hui; Liu, Wen-bin

    2015-01-01

    Highlights: • SiC microparticles improve the mechanical properties of phthalonitrile resin. • Excellent thermal stability achieved by adding SiC particles in phthalonitrile resin. • Adding 20 wt.% of SiC microparticles increases the T g by 38 °C. • Silane coupling agent can enhance the adhesion and dispersion of particles/matrix. - Abstract: A new type of composite based on phthalonitrile resin reinforced with silicon carbide (SiC) microparticles was prepared. For various weight ratios ranging between 0% and 20%, the effect of the micro-SiC particles on the mechanical and thermal properties has been studied. Results from thermal analysis revealed that the starting decomposition temperature and the residual weight were significantly improved upon adding the reinforcing phase. At the maximum micro-SiC loading, dynamic mechanical analysis (DMA) showed an important enhancement in both the storage modulus and glass transition temperature (T g ), reaching 3.1 GPa and 338 °C, respectively. The flexural strength and modulus as well as the microhardness were significantly enhanced by adding the microfillers. Tensile test revealed enhancements in the composites toughness upon adding the microparticles. Polarization optical microscope (POM) and scanning electron microscope (SEM) analysis confirmed that mechanical and thermal properties improvements are essentially attributed to the good dispersion and adhesion between the particles and the resin

  9. Improvement in mechanical properties of high concentration particle doped thermoset composites

    International Nuclear Information System (INIS)

    Ahmed, N.

    2009-01-01

    The paper relates to high concentration particle doped composites based on thermosetting polymer systems in which the sequential addition of particles of certain size distribution is followed by curing and casting of the slurry to form a thermoset composite. Conventionally, at a threshold of beyond 90% of particles by weight of the polymer using triglyceride, the mechanical properties of the composite exhibit a sharp decline. The present research mitigates this behavior by incorporating a unique combination of cross-linking agents in the base polymer to impart exceptional mechanical properties to the composite. More specifically, the base polymer consists of butadiene, with triglyceride as cross-linking agent together with hydroxy-alkane as the chain extension precursors, when tune to the appropriate level of hard segment ratio in the polymer. An added advantage according to the present work resides in the analytical nature of butadiene pre-polymer as opposed to natural product; traditional composites based on natural sources are hampered by their inconsistent chemical composition and poor shelf life in the fabricated composite. The thermoset composite according the present research exhibits superior tensile strength (200-300 psi) properties using particle loading as high as 92% by weight of the fabricated composite as measured on a Tinius Olsen machine. Dynamic Mechanical Testing reveals interesting combination of storage and loss moduli in the fabricated specimens as a function of optimizing the thermal response of the viscoelastic composite to imposed vibration loading. (author)

  10. Nanodiamond particles/PVDF nanocomposite flexible films: thermal, mechanical and physical properties

    Science.gov (United States)

    Jaleh, Babak; Sodagar, Shima; Momeni, Amir; Jabbari, Ameneh

    2016-08-01

    Recently, polymer nanocomposites reinforced with nanoparticles have attracted a lot of attention due to their unique physical and mechanical properties. In this work, poly (vinylidene fluoride)/nanodiamond particles nanocomposite films were prepared by solution casting method with various nanodiamond particles contents. The samples were investigated by Fourier transform infrared spectroscopy and x-ray diffraction technique. The results revealed an obvious α to β-phase transformation compared to pure PVDF. The most (or the maximum) phase transformation from α to β-phase (>90%) was found for nanocomposite film with 8% wt nanodiamond particles. Scanning electron micrographs showed considerable decrease in the size of spherulitic crystal structure of PVDF with adding nanoparticles. The photoluminescence property of nanocomposite films was investigated by photoluminescence spectroscopy and the optical band gap value was calculated from the UV-visible absorption spectra. The results showed that after the incorporation of nanoparticles into PVDF, the value of optical band gap decreased. Thermal stability of samples was studied by thermogravimetric analysis. Due to an increase in the electroactive phase (β) percentage by adding nanoparticles, the resistance of samples to thermal degradation improved. The mechanical properties of samples were investigated by tensile test and hardness measurements. The elastic modulus and hardness of samples were enhanced by adding nanodiamond particles and elongation to fracture decreased.

  11. Electromagnetic absorbing property of the flaky carbonyl iron particles by chemical corrosion process

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Dianliang, E-mail: 272895980@qq.com [College of Aeronautical Engineering, Jilin Institute of Chemical Technology, Jilin 132022 (China); Liu, Ting; Zhou, Li [College of Aeronautical Engineering, Jilin Institute of Chemical Technology, Jilin 132022 (China); Xu, Yonggang [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai 200438 (China)

    2016-12-01

    The flaky carbonyl iron particles (CIPs) were prepared using a milling process at the first step, then the chemical corrosion process was done to optimize the particle shape. The particle morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2–18 GHz and the reflection loss (RL) was calculated. The results showed that the saturation magnetization value of the CIPs decreased as the CIPs was corroded to the small flakes in chemical corrosion process. The diffraction peaks of the single α-Fe existed in the XRD pattern of CIPs, and the characteristic peaks was more obvious and the intensity of the diffraction pattern was lower by corrosion. The permittivity and the permeability of the corroded milling CIPs was a little larger than the milling CIPs, it was due to the larger aspect ratio based on the fitting calculation process. At thickness 0.6 mm and 0.8 mm, the corroded milling CIPs composite had the better absorbing property than the other two samples. The frequency band (RL<−5 dB) could be widened to 8.96–18 GHz at 0.6 mm and 5.92–18 GHz at 0.8 mm, and RL less than −8 dB began to exist in 8.96–14.72 GHz at 0.8 mm. - Graphical abstract: The property of absorber using corrosion process could be enhanced. - Highlights: • The chemical corrosion process was done to optimize the particle shape. • The permittivity and permeability of corroded milling CIPs increased. • The aspect ratio of flaky CIPs increased in the corrosion process. • The corroded milling CIPs composite had the better absorbing property.

  12. Dynamical properties of a particle in a time-dependent double-well potential

    International Nuclear Information System (INIS)

    Leonel, Edson D; McClintock, P V E

    2004-01-01

    Some chaotic properties of a classical particle interacting with a time-dependent double-square-well potential are studied. The dynamics of the system is characterized using a two-dimensional nonlinear area-preserving map. Scaling arguments are used to study the chaotic sea in the low-energy domain. It is shown that the distributions of successive reflections and of corresponding successive reflection times obey power laws with the same exponent. If one or both wells move randomly, the particle experiences the phenomenon of Fermi acceleration in the sense that it has unlimited energy growth

  13. Comparison of mechanical and tribotechnical properties of UHMWPE reinforced with basalt fibers and particles

    Science.gov (United States)

    Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Qitao, Huang; Ivanova, L. R.

    2016-11-01

    Mechanical and tribotechnical properties of UHMWPE composites reinforced with basalt fibers and particles under dry sliding friction and abrasion were investigated. It is shown that adding of the basalt particles provides higher wear resistance under the dry sliding friction while at abrasion filling by the basalt fibers is more efficient since the wear resistance of the reinforced UHMWPE composites is by 3.7 times higher in contrast with the neat polymer. Wear mechanisms of the polymeric UHMWPE composites under various types of wear are discussed.

  14. Comparison of Micro- and Nanoscale Fe+3-Containing (Hematite) Particles for Their Toxicological Properties in Human Lung Cells In Vitro

    NARCIS (Netherlands)

    Bhattacharya, K.; Hoffmann, E.; Schins, R.F.P.; Boertz, J.; Prantl, E.M.; Alink, G.M.; Byrne, H.J.; Kuhlbusch, T.A.J.; Rahman, Q.; Wiggers, H.; Schulz, C.; Dopp, E.

    2012-01-01

    The specific properties of nanoscale particles, large surface-to-mass ratios and highly reactive surfaces, have increased their commercial application in many fields. However, the same properties are also important for the interaction and bioaccumulation of the nonbiodegradable nanoscale particles

  15. Physicochemical conditions and properties of particles in urban runoff and rivers: Implications for runoff pollution.

    Science.gov (United States)

    Wang, Qian; Zhang, Qionghua; Wu, Yaketon; Wang, Xiaochang C

    2017-04-01

    In this study, to gain an improved understanding of the fate and fractionation of particle-bound pollutants, we evaluated the physicochemical conditions and the properties of particles in rainwater, urban runoff, and rivers of Yixing, a city with a large drainage density in the Taihu Lake Basin, China. Road runoff and river samples were collected during the wet and dry seasons in 2015 and 2016. There were significant differences between the physicochemical conditions (pH, oxidation-reduction potential (ORP), and electroconductivity (EC)) of rainwater, runoff, and rivers. The lowest pH and highest ORP values of rainwater provide the optimal conditions for leaching of particle-bound pollutants such as heavy metals. The differences in the physicochemical conditions of the runoff and rivers may contribute to the redistribution of pollutants between particulate and dissolved phases after runoff is discharged into waterways. Runoff and river particles were mainly composed of silt and clay (runoff particles contained a higher proportion of nano-scale particles (runoff pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Effects of particles thickness and veneer reiforced layer in the properties of oriented strand boards OSB

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2009-03-01

    Full Text Available This work evaluated the effects of particle thickness and veneer reinforced layer on the physical and mechanicalproperties of OSB made of Pinus taeda L. The boards were manufactured with particle thickness of 0.4, 0.7 and 1.0 mm and phenolformaldehyderesin in the proportion of 6% of solid content. To the veneer reinforced layer was used veneer from Pinus taeda with 2.0mm of thickness. The increase in the slenderness (length/thickness ratio of thins particles, results in the higher values of MOE andMOR in the cross direction. The increase in the particles thickness contributed to higher values of the board internal bond. Thedifferent particles thickness did not clearly affected on the physical properties of OSB. The veneer reinforced layer results in the higheraverage values of MOE and MOR in the cross direction. All of the results of MOE and MOR obtained for boards with differentthickness attend tominimum values required per CSA 0437 (CSA, 1993. For the internal bond, the results were satisfactory to boardsmanufactured with particles thickness of 0.7 and 1.0 mm. According to the results the main conclusions were: (i The increase in theparticles thickness contributed to lower values of MOE and MOR, and higher values of the board internal bond; (ii the veneerreinforced layer increased MOE and MOR values in the cross direction.

  17. Selected mechanical properties of aluminum composite materials reinforced with SiC particles

    Directory of Open Access Journals (Sweden)

    A. Kurzawa

    2008-07-01

    Full Text Available This work presents the results of research concerning influence of ceramic particles’ content of silicon carbide on selected mechanical properties of type AW-AlCu4Mg2Mn - SiC composite materials. Composites produced of SiC particles with pressure infiltration method of porous preform and subject to hot plastic forming in the form of open die forging were investigated. The experimental samples contained from 5% up to 45% of reinforcing SiC particles of 8÷10μm diameter. Studies of strength properties demonstrated that the best results, in case of tensile strength as well as offset yield strength, might be obtained while applying reinforcement in the amount of 20-25% vol. of SiC. Application of higher than 25% vol. contents of reinforcing particles leads to gradual strength loss. The investigated composites were characterized by very high functional properties, such as hardness and abrasive wear resistance, whose values increase strongly with the increase of reinforcement amount. The presented results of the experiments shall allow for a more precise component selection of composite materials at the stage of planning and design of their properties.

  18. Mechanical properties of dental resin composites by co-filling diatomite and nanosized silica particles

    International Nuclear Information System (INIS)

    Wang Hua; Zhu Meifang; Li Yaogang; Zhang Qinghong; Wang Hongzhi

    2011-01-01

    The aim of this study was to investigate the mechanical property effects of co-filling dental resin composites with porous diatomite and nanosized silica particles (OX-50). The purification of raw diatomite by acid-leaching was conducted in a hot 5 M HCl solution at 80 deg. C for 12 h. Both diatomite and nanosized SiO 2 were silanized with 3-methacryloxypropyltrimethoxysilane. The silanized inorganic particles were mixed into a dimethacrylate resin. Purified diatomite was characterized by X-ray diffraction, UV-vis diffuse reflectance spectroscopy and an N 2 adsorption-desorption isotherm. Silanized inorganic particles were characterized using Fourier transform infrared spectroscopy and a thermogravimetric analysis. The mechanical properties of the composites were tested by three-point bending, compression and Vicker's microhardness. Scanning electron microscopy was used to show the cross-section morphologies of the composites. Silanization of diatomite and nanosized silica positively reinforced interactions between the resin matrix and the inorganic particles. The mechanical properties of the resin composites gradually increased with the addition of modified diatomite (m-diatomite). The fracture surfaces of the composites exhibited large fracture steps with the addition of m-diatomite. However, when the mass fraction of m-diatomite was greater than 21 wt.% with respect to modified nanosized silica (mOX-50) and constituted 70% of the resin composite by weight, the mechanical properties of the resin composites started to decline. Thus, the porous structure of diatomite appears to be a crucial factor to improve mechanical properties of resin composites.

  19. Mechanical properties of dental resin composites by co-filling diatomite and nanosized silica particles

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hua; Zhu Meifang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Li Yaogang [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Donghua University, Shanghai 201620 (China); Zhang Qinghong, E-mail: zhangqh@dhu.edu.cn [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Donghua University, Shanghai 201620 (China); Wang Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China)

    2011-04-08

    The aim of this study was to investigate the mechanical property effects of co-filling dental resin composites with porous diatomite and nanosized silica particles (OX-50). The purification of raw diatomite by acid-leaching was conducted in a hot 5 M HCl solution at 80 deg. C for 12 h. Both diatomite and nanosized SiO{sub 2} were silanized with 3-methacryloxypropyltrimethoxysilane. The silanized inorganic particles were mixed into a dimethacrylate resin. Purified diatomite was characterized by X-ray diffraction, UV-vis diffuse reflectance spectroscopy and an N{sub 2} adsorption-desorption isotherm. Silanized inorganic particles were characterized using Fourier transform infrared spectroscopy and a thermogravimetric analysis. The mechanical properties of the composites were tested by three-point bending, compression and Vicker's microhardness. Scanning electron microscopy was used to show the cross-section morphologies of the composites. Silanization of diatomite and nanosized silica positively reinforced interactions between the resin matrix and the inorganic particles. The mechanical properties of the resin composites gradually increased with the addition of modified diatomite (m-diatomite). The fracture surfaces of the composites exhibited large fracture steps with the addition of m-diatomite. However, when the mass fraction of m-diatomite was greater than 21 wt.% with respect to modified nanosized silica (mOX-50) and constituted 70% of the resin composite by weight, the mechanical properties of the resin composites started to decline. Thus, the porous structure of diatomite appears to be a crucial factor to improve mechanical properties of resin composites.

  20. Dynamic properties of micro-particles in ultrasonic transportation using phase-controllable standing waves

    International Nuclear Information System (INIS)

    Jia, Kun; Mei, Deqing; Meng, Jianxin; Yang, Keji

    2014-01-01

    Ultrasonic manipulation has become an attractive method for surface-sensitive objects in micro-technology. Related phenomena, such as radiation force, multiple scattering, and acoustic streaming, have been widely studied. However, in current studies, the behavior of micro-particles in potential force fields is always analyzed in a quasi-static manner. We developed a dynamic model of a dilute micro-particle in the commonly used two-dimensional ultrasonic manipulation system to provide a systemic and quantitative analysis of the transient properties of particle movement. In this model, the acoustic streaming and hydrodynamic forces, omitted in previous work, were both considered. The trajectory of a spherical silica particle with different initial conditions was derived by numerically solving the established nonlinear differential integral equation system, which was then validated experimentally. The envelope of the experimental data on the x-axis showed good agreement with the theoretical calculation, and the greater influence on the y-axis of the deviation between the actual sound field and the ideal distribution employed in our dynamic model could account for the differences in displacement in that direction. Finally, the influence of particle size on its movement and the effect of acoustic streaming on calculating the hydrodynamic forces for an isolated particle with motion relative to the fluid were analyzed theoretically. It was found that the ultrasonic manipulation system will translate from an under-damped system to an over-damped system with a decrease in particle size and the micro-scale acoustic streaming velocity was negligible when calculating the hydrodynamic forces on the particle in the ultrasonic manipulation system.

  1. Dynamic properties of micro-particles in ultrasonic transportation using phase-controllable standing waves

    Science.gov (United States)

    Jia, Kun; Mei, Deqing; Meng, Jianxin; Yang, Keji

    2014-10-01

    Ultrasonic manipulation has become an attractive method for surface-sensitive objects in micro-technology. Related phenomena, such as radiation force, multiple scattering, and acoustic streaming, have been widely studied. However, in current studies, the behavior of micro-particles in potential force fields is always analyzed in a quasi-static manner. We developed a dynamic model of a dilute micro-particle in the commonly used two-dimensional ultrasonic manipulation system to provide a systemic and quantitative analysis of the transient properties of particle movement. In this model, the acoustic streaming and hydrodynamic forces, omitted in previous work, were both considered. The trajectory of a spherical silica particle with different initial conditions was derived by numerically solving the established nonlinear differential integral equation system, which was then validated experimentally. The envelope of the experimental data on the x-axis showed good agreement with the theoretical calculation, and the greater influence on the y-axis of the deviation between the actual sound field and the ideal distribution employed in our dynamic model could account for the differences in displacement in that direction. Finally, the influence of particle size on its movement and the effect of acoustic streaming on calculating the hydrodynamic forces for an isolated particle with motion relative to the fluid were analyzed theoretically. It was found that the ultrasonic manipulation system will translate from an under-damped system to an over-damped system with a decrease in particle size and the micro-scale acoustic streaming velocity was negligible when calculating the hydrodynamic forces on the particle in the ultrasonic manipulation system.

  2. Effects of the shape properties of talc and quartz particles on the wettability based separation processes

    International Nuclear Information System (INIS)

    Hicyilmaz, C.; Ulusoy, U.; Yekeler, M.

    2004-01-01

    Shape properties of talc and quartz particles ground by a laboratory size ball, rod, and autogenous mills were studied using scanning electron microscope (SEM). More than 100 particles were measured to do the shape analysis of each mill product. The wettability behavior of (γ c ) a highly hydrophobic of talc mineral was determined by contact angle measurements and micro-flotation tests using a contact angle goniometer and EMDEE MicroFLOT test tube, respectively. On the other hand, wettability (γ c ) of quartz, which is a highly hydrophilic mineral, was determined by the micro-flotation method only. The results showed that the particles ground by rod mill gave higher flatness and elongation ratio, which meant higher hydrophobicity with lower γ c values in the separations by flotation method

  3. Tribological Properties of Aluminum Alloy treated by Fine Particle Peening/DLC Hybrid Surface Modification

    Directory of Open Access Journals (Sweden)

    Nanbu H.

    2010-06-01

    Full Text Available In order to improve the adhesiveness of the DLC coating, Fine Particle Peening (FPP treatment was employed as pre-treatment of the DLC coating process. FPP treatment was performed using SiC shot particles, and then AA6061-T6 aluminum alloy was DLC-coated. A SiC-rich layer was formed around the surface of the aluminum alloy by the FPP treatment because small chips of shot particles were embedded into the substrate surface. Reciprocating sliding tests were conducted to measure the friction coefficients. While the DLC coated specimen without FPP treatment showed a sudden increase in friction coefficient at the early stage of the wear cycles, the FPP/DLC hybrid treated specimen maintained a low friction coefficient value during the test period. Further investigation revealed that the tribological properties of the substrate after the DLC coating were improved with an increase in the amount of Si at the surface.

  4. Synthesis, multi-nonlinear dielectric resonance and electromagnetic absorption properties of hcp-cobalt particles

    International Nuclear Information System (INIS)

    Wen, Shulai; Liu, Ying; Zhao, Xiuchen; Cheng, Jingwei; Li, Hong

    2014-01-01

    Hcp-cobalt particles were successfully prepared by a liquid phase reduction method, and the microstructure, static magnetic properties, electromagnetic and microwave absorption properties of the cobalt particles with irregular shape were investigated in detail. The measured results indicate that the saturation magnetization was less than that of hcp-Co single crystals, and the coercivity was larger than that of bulk cobalt crystal. The permittivity presents multi-nonlinear dielectric resonance, which may result from the irregular shape containing parts of cutting angle of dodecahedron of cobalt particles. The real part of permeability decreases with the frequency, and the imaginary part has a wide resonant peak. The paraffin-based composite containing 70 wt% cobalt particles possessed strong absorption characteristics with a minimum RL of −38.97 dB at 10.81 GHz and an absorption band with RL under −10 dB from 8.72 to 13.26 GHz when the thickness is 1.8 mm, which exhibits excellent microwave absorption in middle and high frequency. The architectural design of material morphologies is important for improving microwave absorption properties toward future application. - Highlights: • Hcp-cobalt particles were prepared by a liquid phase reduction method. • The saturation magnetization was less than that of hcp-Co single crystals. • The permittivity presents multi-nonlinear dielectric resonance. • The real part of permeability decreases with frequency, and the imaginary part presents a wide resonant peak. • The paraffin-based composite possessed a minimum RL of −38.97 dB at 10.81 GHz

  5. Ice nucleation properties of atmospheric aerosol particles collected during a field campaign in Cyprus

    Science.gov (United States)

    Yordanova, Petya; Maier, Stefanie; Lang-Yona, Naama; Tamm, Alexandra; Meusel, Hannah; Pöschl, Ulrich; Weber, Bettina; Fröhlich-Nowoisky, Janine

    2017-04-01

    Atmospheric aerosol particles, including desert and soil dust as well as marine aerosols, are well known to act as ice nuclei (IN) and thus have been investigated in numerous ice nucleation studies. Based on their cloud condensation nuclei potential and their impacts on radiative properties of clouds (via scattering and absorption of solar radiation), aerosol particles may significantly affect the cloud and precipitation development. Atmospheric aerosols of the Eastern Mediterranean have been described to be dominated by desert dust, but only little is known on their composition and ice nucleating properties. In this study we investigated the ice nucleating ability of total suspended particles (TSP), collected at the remote site Agia Marina Xyliatou on Cyprus during a field campaign in April 2016. Airborne TSP samples containing air masses of various types such as African (Saharan) and Arabian dust and European and Middle Eastern pollution were collected on glass fiber filters at 24 h intervals. Sampling was performed ˜5 m above ground level and ˜521 m above sea level. During the sampling period, two major dust storms (PM 10max 118 μg/m3 and 66 μg/m3) and a rain event (rainfall amount: 3.4 mm) were documented. Chemical and physical characterizations of the particles were analyzed experimentally through filtration, thermal, chemical and enzyme treatments. Immersion freezing experiments were performed at relatively high subzero temperatures (-1 to -15˚ C) using the mono ice nucleation array. Preliminary results indicate that highest IN particle numbers (INPs) occurred during the second dust storm event with lower particle concentrations. Treatments at 60˚ C lead to a gradual IN deactivation, indicating the presence of biological INPs, which were observed to be larger than 300 kDa. Additional results originating from this study will be shown. Acknowledgement: This work was funded by the DFG Ice Nuclei Research Unit (INUIT).

  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. Single-particle properties of the Hubbard model in a novel three-pole approximation

    Science.gov (United States)

    Di Ciolo, Andrea; Avella, Adolfo

    2018-05-01

    We study the 2D Hubbard model using the Composite Operator Method within a novel three-pole approximation. Motivated by the long-standing experimental puzzle of the single-particle properties of the underdoped cuprates, we include in the operatorial basis, together with the usual Hubbard operators, a field describing the electronic transitions dressed by the nearest-neighbor spin fluctuations, which play a crucial role in the unconventional behavior of the Fermi surface and of the electronic dispersion. Then, we adopt this approximation to study the single-particle properties in the strong coupling regime and find an unexpected behavior of the van Hove singularity that can be seen as a precursor of a pseudogap regime.

  8. Enhancement of transport properties of a Brownian particle due to quantum effects: Smoluchowski limit

    International Nuclear Information System (INIS)

    Shit, Anindita; Chattopadhyay, Sudip; Chaudhuri, Jyotipratim Ray

    2012-01-01

    Graphical abstract: By invoking physically motivated coordinate transformation into quantum Smoluchowski equation, we have presented a transparent treatment for the determination of the effective diffusion coefficient and current of a quantum Brownian particle. Substantial enhancement in the efficiency of the diffusive transport is envisaged due to the quantum correction effects. Highlights:: ► Transport of a quantum Brownian particle in a periodic potential has been addressed. ► Governing quantum Smoluchowski equation (QSE) includes state dependent diffusion. ► A coordinate transformation is used to recast QSE with constant diffusion. ► Transport properties increases in comparison to the corresponding classical result. ► This enhancement is purely a quantum effect. - Abstract: The transport property of a quantum Brownian particle that interacts strongly with a bath (in which a typical damping constant by far exceeds a characteristic frequency of the isolated system) under the influence of a tilted periodic potential has been studied by solving quantum Smoluchowski equation (QSE). By invoking physically motivated coordinate transformation into QSE, we have presented a transparent treatment for the determination of the effective diffusion coefficient of a quantum Brownian particle and the current (the average stationary velocity). Substantial enhancement in the efficiency of the diffusive transport is envisaged due to the quantum correction effects only if the bath temperature hovers around an appropriate range of intermediate values. Our findings also confirm the results obtained in the classical cases.

  9. Properties and toxicological effects of particles from the interaction between tyres, road pavement and winter traction material

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Mats [Swedish National Road and Transport Research Institute (VTI), SE-581 95 Linkoeping (Sweden)], E-mail: mats.gustafsson@vti.se; Blomqvist, Goeran [Swedish National Road and Transport Research Institute (VTI), SE-581 95 Linkoeping (Sweden); Gudmundsson, Anders; Dahl, Andreas [Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden); Swietlicki, Erik [Division of Nuclear Physics, Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden); Bohgard, Mats [Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden); Lindbom, John; Ljungman, Anders [Faculty of Health Sciences, Department of Molecular and Clinical Medicine, Division of Occupational and Environmental Medicine, SE-581 85 Linkoeping (Sweden)

    2008-04-15

    In regions where studded tyres and traction material are used during winter, e.g. the Nordic countries, northern part of USA, Canada, and Japan, mechanically generated particles from traffic are the main reason for high particle mass concentrations in busy street and road environments. In many Nordic municipalities the European environmental quality standard for inhalable particles (PM{sub 10}) is exceeded due to these particles. In this study, particles from the wear of studded and studless friction tyres on two pavements and traction sanding were generated using a road simulator. The particles were characterized using particle sizers, Particle Induced X-Ray Emission Analysis and electron microscopy. Cell studies were conducted on particles sampled from the tests with studded tyres and compared with street environment, diesel exhaust and subway PM{sub 10}, respectively. The results show that in the road simulator, where resuspension is minimized, studded tyres produce tens of times more particles than friction tyres. Chemical analysis of the sampled particles shows that the generated wear particles consist almost entirely of minerals from the pavement stone material, but also that Sulfur is enriched for the submicron particles and that Zink is enriched for friction tyres for all particles sizes. The chemical data can be used for source identification and apportionment in urban aerosol studies. A mode of ultra-fine particles was also present and is hypothesised to originate in the tyres. Further, traction material properties affect PM{sub 10} emission. The inflammatory potential of the particles from wear of pavements seems to depend on type of pavement and can be at least as potent as diesel exhaust particles. The results imply that there is a need and a good potential to reduce particle emission from pavement wear and winter time road and street operation by adjusting both studded tyre use as well as pavement and traction material properties.

  10. Properties and toxicological effects of particles from the interaction between tyres, road pavement and winter traction material

    International Nuclear Information System (INIS)

    Gustafsson, Mats; Blomqvist, Goeran; Gudmundsson, Anders; Dahl, Andreas; Swietlicki, Erik; Bohgard, Mats; Lindbom, John; Ljungman, Anders

    2008-01-01

    In regions where studded tyres and traction material are used during winter, e.g. the Nordic countries, northern part of USA, Canada, and Japan, mechanically generated particles from traffic are the main reason for high particle mass concentrations in busy street and road environments. In many Nordic municipalities the European environmental quality standard for inhalable particles (PM 10 ) is exceeded due to these particles. In this study, particles from the wear of studded and studless friction tyres on two pavements and traction sanding were generated using a road simulator. The particles were characterized using particle sizers, Particle Induced X-Ray Emission Analysis and electron microscopy. Cell studies were conducted on particles sampled from the tests with studded tyres and compared with street environment, diesel exhaust and subway PM 10 , respectively. The results show that in the road simulator, where resuspension is minimized, studded tyres produce tens of times more particles than friction tyres. Chemical analysis of the sampled particles shows that the generated wear particles consist almost entirely of minerals from the pavement stone material, but also that Sulfur is enriched for the submicron particles and that Zink is enriched for friction tyres for all particles sizes. The chemical data can be used for source identification and apportionment in urban aerosol studies. A mode of ultra-fine particles was also present and is hypothesised to originate in the tyres. Further, traction material properties affect PM 10 emission. The inflammatory potential of the particles from wear of pavements seems to depend on type of pavement and can be at least as potent as diesel exhaust particles. The results imply that there is a need and a good potential to reduce particle emission from pavement wear and winter time road and street operation by adjusting both studded tyre use as well as pavement and traction material properties

  11. Naima: a Python package for inference of particle distribution properties from nonthermal spectra

    Science.gov (United States)

    Zabalza, V.

    2015-07-01

    The ultimate goal of the observation of nonthermal emission from astrophysical sources is to understand the underlying particle acceleration and evolution processes, and few tools are publicly available to infer the particle distribution properties from the observed photon spectra from X-ray to VHE gamma rays. Here I present naima, an open source Python package that provides models for nonthermal radiative emission from homogeneous distribution of relativistic electrons and protons. Contributions from synchrotron, inverse Compton, nonthermal bremsstrahlung, and neutral-pion decay can be computed for a series of functional shapes of the particle energy distributions, with the possibility of using user-defined particle distribution functions. In addition, naima provides a set of functions that allow to use these models to fit observed nonthermal spectra through an MCMC procedure, obtaining probability distribution functions for the particle distribution parameters. Here I present the models and methods available in naima and an example of their application to the understanding of a galactic nonthermal source. naima's documentation, including how to install the package, is available at http://naima.readthedocs.org.

  12. Quantum Radiation Properties of Dirac Particles in General Nonstationary Black Holes

    Directory of Open Access Journals (Sweden)

    Jia-Chen Hua

    2014-01-01

    Full Text Available Quantum radiation properties of Dirac particles in general nonstationary black holes in the general case are investigated by both using the method of generalized tortoise coordinate transformation and considering simultaneously the asymptotic behaviors of the first-order and second-order forms of Dirac equation near the event horizon. It is generally shown that the temperature and the shape of the event horizon of this kind of black holes depend on both the time and different angles. Further, we give a general expression of the new extra coupling effect in thermal radiation spectrum of Dirac particles which is absent from the thermal radiation spectrum of scalar particles. Also, we reveal a relationship that is ignored before between thermal radiation and nonthermal radiation in the case of scalar particles, which is that the chemical potential in thermal radiation spectrum is equal to the highest energy of the negative energy state of scalar particles in nonthermal radiation for general nonstationary black holes.

  13. Effect of sorghum flour composition and particle size on quality properties of gluten-free bread.

    Science.gov (United States)

    Trappey, Emily Frederick; Khouryieh, Hanna; Aramouni, Fadi; Herald, Thomas

    2015-04-01

    White, food-grade sorghum was milled to flour of varying extraction rates (60%, 80%, and 100%) and pin-milled at different speeds (no pin-milling, low-speed, and high-speed) to create flours of both variable composition and particle size. Flours were characterized for flour composition, total starch content, particle size distribution, color, damaged starch, and water absorption. Bread was characterized for specific volume, crumb structure properties, and crumb firmness. Significant differences were found (P Breads produced from 60% extraction flour had significantly higher specific volumes, better crumb properties, and lower crumb firmness when compared with all other extractions and flour types. The specific volume of bread slices ranged from 2.01 mL/g (100% extraction, no pin-milling) to 2.54 mL/g (60% extraction, low-speed pin-milling), whereas the firmness ranged from 553.28 g (60% extraction, high-speed pin-milling) to 1096.26 g (commercial flour, no pin-milling). The bread characteristics were significantly impacted by flour properties, specifically particle size, starch damage, and fiber content (P < 0.05). © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  14. The Field-Dependent Rheological Properties of Magnetorheological Grease Based on Carbonyl-Iron-Particles

    Science.gov (United States)

    Mohamad, N.; Mazlan, S. A.; Ubaidillah; Choi, Seung-Bok; Nordin, M. F. M.

    2016-09-01

    This paper presents dynamic viscoelastic properties of magnetorheological (MR) grease under variation of magnetic fields and magnetic particle fractions. The tests to discern the field-dependent properties are undertaken using both rotational and oscillatory shear rheometers. As a first step, the MR grease is developed by dispersing the carbonyl iron (CI) particles into grease medium with a mechanical stirrer. Experimental data are obtained by changing the magnetic field from 0 to 0.7 T at room temperature of 25 °C. It is found that a strong Payne effect limits the linear viscoelastic region of MR grease at strains above 0.1%. The results exhibit a high dynamic yield stress which is equivalent to Bingham plastic rheological model, and show relatively good MR effect at high shear rate of 2000 s-1. In addition, high dispersion of the magnetic particles and good thermal properties are proven. The results presented in this work directly indicate that MR grease is a smart material candidate that could be widely applicable to various fields including vibration control.

  15. Killer smog of London, 50 years on: particle properties and oxidative capacity.

    Science.gov (United States)

    Whittaker, Andy; BéruBé, Kelly; Jones, Tim; Maynard, Robert; Richards, Roy

    2004-12-01

    Total suspended particulate (TSP) samples collected on glass fibre filters in London before (1955) and after (1958-1974) the Clean Air Act was examined for physicochemical characteristics and oxidative capacity. High-resolution microscopy identified most of the material as soot with smelter spheres, fly ash (FA), sodium chloride and calcium sulphate particles. Image analysis (IA) was used to show that most of the soot aggregates were less than 1 microm in size and contained chains of individual particles of 10-50 nm. Speed mapping of large agglomerates of the historic particles confirmed that the samples were enriched with soot probably derived from a sulphur-rich coal called nutty slack which was used extensively at this time. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to examine elemental composition. Meaningful quantitation of certain elements (Mg, Al and Zn) proved impossible because they were in high quantities in the glass fibre filters. However, high quantities of Fe>Pb>Cu>Mn>V>As were detected which may explain in part the bioreactivity of the samples. Using a simple in vitro test of oxidative capacity (plasmid assay), one historic particulate sample (1958) showed three times the activity of a modern-day diesel exhaust particle (DEP) sample but ten times less activity than a modern-day urban ambient particle collection. Such studies are continuing to link particle physicochemical properties and bioreactivity with a wider range of the samples collected between 1955 and 74 and how such historic samples compare with present-day London ambient particles.

  16. Aqueous Lubrication, Structure and Rheological Properties of Whey Protein Microgel Particles.

    Science.gov (United States)

    Sarkar, Anwesha; Kanti, Farah; Gulotta, Alessandro; Murray, Brent S; Zhang, Shuying

    2017-12-26

    Aqueous lubrication has emerged as an active research area in recent years due to its prevalence in nature in biotribological contacts and its enormous technological soft-matter applications. In this study, we designed aqueous dispersions of biocompatible whey-protein microgel particles (WPM) (10-80 vol %) cross-linked via disulfide bonding and focused on understanding their rheological, structural and biotribological properties (smooth polydimethylsiloxane (PDMS) contacts, R a ball bearings", the latter supported by negligible change in size and microstructure of the WPM particles after tribology. An ultralow boundary friction coefficient, μ ≤ 0.03 was achieved using WPM between O 2 plasma-treated hydrophilic PDMS contacts coated with bovine submaxillary mucin (water contact angle 47°), and electron micrographs revealed that the WPM particles spread effectively as a layer of particles even at low ϕ∼ 10%, forming a lubricating load-bearing film that prevented the two surfaces from true adhesive contact. However, above an optimum volume fraction, μ increased in HL+BSM surfaces due to the interpenetration of particles that possibly impeded effective rolling, explaining the slight increase in friction. These effects are reflected in the highly shear thinning nature of the WPM dispersions themselves plus the tendency for the apparent viscosity to fall as dispersions are forced to very high volume fractions. The present work demonstrates a novel approach for providing ultralow friction in soft polymeric surfaces using proteinaceous microgel particles that satisfy both load bearing and kinematic requirements. These findings hold great potential for designing biocompatible particles for aqueous lubrication in numerous soft matter applications.

  17. Retrieving simulated volcanic, desert dust and sea-salt particle properties from two/three-component particle mixtures using UV-VIS polarization lidar and T matrix

    Directory of Open Access Journals (Sweden)

    G. David

    2013-07-01

    Full Text Available During transport by advection, atmospheric nonspherical particles, such as volcanic ash, desert dust or sea-salt particles experience several chemical and physical processes, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this paper, a new methodology is proposed to analyse this complex vertical layering in the case of a two/three-component particle external mixtures. This methodology relies on an analysis of the spectral and polarization properties of the light backscattered by atmospheric particles. It is based on combining a sensitive and accurate UV-VIS polarization lidar experiment with T-matrix numerical simulations and air mass back trajectories. The Lyon UV-VIS polarization lidar is used to efficiently partition the particle mixture into its nonspherical components, while the T-matrix method is used for simulating the backscattering and depolarization properties of nonspherical volcanic ash, desert dust and sea-salt particles. It is shown that the particle mixtures' depolarization ratio δ p differs from the nonspherical particles' depolarization ratio δns due to the presence of spherical particles in the mixture. Hence, after identifying a tracer for nonspherical particles, particle backscattering coefficients specific to each nonspherical component can be retrieved in a two-component external mixture. For three-component mixtures, the spectral properties of light must in addition be exploited by using a dual-wavelength polarization lidar. Hence, for the first time, in a three-component external mixture, the nonsphericity of each particle is taken into account in a so-called 2β + 2δ formalism. Applications of this new methodology are then demonstrated in two case studies carried out in Lyon, France, related to the mixing of Eyjafjallajökull volcanic ash with sulfate particles (case of a two-component mixture and to the mixing of dust with sea-salt and water-soluble particles

  18. Laboratory and Cloud Chamber Studies of Formation Processes and Properties of Atmospheric Ice Particles

    Science.gov (United States)

    Leisner, T.; Abdelmonem, A.; Benz, S.; Brinkmann, M.; Möhler, O.; Rzesanke, D.; Saathoff, H.; Schnaiter, M.; Wagner, R.

    2009-04-01

    The formation of ice in tropospheric clouds controls the evolution of precipitation and thereby influences climate and weather via a complex network of dynamical and microphysical processes. At higher altitudes, ice particles in cirrus clouds or contrails modify the radiative energy budget by direct interaction with the shortwave and longwave radiation. In order to improve the parameterisation of the complex microphysical and dynamical processes leading to and controlling the evolution of tropospheric ice, laboratory experiments are performed at the IMK Karlsruhe both on a single particle level and in the aerosol and cloud chamber AIDA. Single particle experiments in electrodynamic levitation lend themselves to the study of the interaction between cloud droplets and aerosol particles under extremely well characterized and static conditions in order to obtain microphysical parameters as freezing nucleation rates for homogeneous and heterogeneous ice formation. They also allow the observation of the freezing dynamics and of secondary ice formation and multiplication processes under controlled conditions and with very high spatial and temporal resolution. The inherent droplet charge in these experiments can be varied over a wide range in order to assess the influence of the electrical state of the cloud on its microphysics. In the AIDA chamber on the other hand, these processes are observable under the realistic dynamic conditions of an expanding and cooling cloud- parcel with interacting particles and are probed simultaneously by a comprehensive set of analytical instruments. By this means, microphysical processes can be studied in their complex interplay with dynamical processes as for example coagulation or particle evaporation and growth via the Bergeron - Findeisen process. Shortwave scattering and longwave absorption properties of the nucleating and growing ice crystals are probed by in situ polarised laser light scattering measurements and infrared extinction

  19. The Effect Of Organic Surfactants On The Properties Of Common Hygroscopic Particles: Effective Densities, Reactivity And Water Evaporation Of Surfactant Coated Particles

    Science.gov (United States)

    Cuadrarodriguez, L.; Zelenyuk, A.; Imre, D.; Ellison, B.

    2006-12-01

    Measurements of atmospheric aerosol compositions routinely show that organic compounds account for a very large fraction of the particle mass. The organic compounds that make up this aerosol mass represent a wide range of molecules with a variety of properties. Many of the particles are composed of hygroscopic salts like sulfates, nitrates and sea-salt internally mixed with organics. While the properties of the hygroscopic salts are known, the effect of the organic compounds on the microphysical and chemical properties which include CCN activity is not clear. .One particularly interesting class of internally mixed particles is composed of aqueous salts solutions that are coated with organic surfactants which are molecules with long aliphatic chain and a water soluble end. Because these molecules tend to coat the particles' surfaces, a monolayer might be sufficient to drastically alter their hygroscopic properties, their CCN activity, and reactivity. The aliphatic chains, being exposed to the oxidizing atmosphere are expected to be transformed through heterogeneous chemistry, yielding complex products with mixed properties. We will report the results from a series of observations on ammonium sulfate, sodium chloride and sea salt particles coated with three types of surfactant molecules: sodium lauryl sulfate, sodium oleate and laurtrimonium chloride. We have been able to measure the effective densities of internally mixed particles with a range of surfactant concentration that start below a monolayer and extend all the way to particles composed of pure surfactant. For many of the measurements the data reveal a rather complex picture that cannot be simply interpreted in terms of the known pure-compound densities. For unsaturated hydrocarbons we observed and quantified the effect of oxidation by ozone on particle size, effective density and individual particle mass spectral signatures. One of the more important properties of these surfactants is that they can form a

  20. A study on properties-performances of coated particle fuel and on-line DB establishment

    International Nuclear Information System (INIS)

    Kim, Yong Soo; Lee, Hyo Cheol; Jang, Jeong Nam; Kwon, Seok Hwan

    2007-03-01

    Recently national project for HTGR for hydrogen production has been kicked off. However, For the successful development of the high temperature gas cooled reactor high temperature and burn-up dependent properties of the reactor materials are essentially and crucially required. Therefore, it was proposed to build up the materials properties and fuel performance data base. In this study, a phase - 1 properties and performance DB for coated particle fuel was developed. This database report consists two sections: materials properties and fuel performance. The materials properties has three parts: kernel materials, carbide coating materials, and fuel elements and graphite matrix. UO2 and UCO belong to kernel materials while PyC, SiC, and ZrC comprises the coating materials section. Thermal, mechanical and physical properties data of these materials were collected, reviewed, and summarized. Additionally, the property change induced by manufacture process and irradiation were reviewed. Fuel performance data were also collected, reviewed, and analyzed based on the key phenomena and failure mechanism, These performance data are divided into two: normal and accident. All of these data will be accessible in the pc based stand-alone system. These results will be directly used for HTGR fuel design and fabrication and preliminary fuel performance analysis under irradiation

  1. Properties of particleboards fabricated with eucalyptus (Eucalyptus urophylla, parica (Schizolobium amazonicum and vassoura (Sida spp. particles

    Directory of Open Access Journals (Sweden)

    Juliana Jerásio Bianche

    2012-12-01

    Full Text Available The genus Sida may become a promising alternative source for the production of particleboards. Nowadays it is used for manufacturing ropes due to the quality of its fibers, however, there is no research relating the production of particleboards using this lignocelluloses material. This study aimed to evaluate the effect of eucalyptus (Eucalyptus urophylla, paricá (Schizolobium amazonicum and vassoura (Sida spp. on the physical and mechanical properties of particleboard. Particleboard contained 25, 50, 75 and 100% of eucalyptus and paricá or eucalytus and vassoura or paricá an vassoura were fabricated. Two (6% and 8% amounts of urea-formaldehyde adhesive were used. The physical and mechanical properties were determined according to NBR / ABNT 14810-3 (ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS - ABNT, 2002. It was observed that increase in resin content in the improved some physical and mechanical properties. It was concluded that the amount of vassoura particles on panels had different effects depending on the species used. The increase in the percentage of vassoura particles in the Eucalyptus panels did not affect the internal bond, screw withdrawal and hardness. Increasing the percentage of vassoura particles on the panels produced with paricá did not affect its hardness and resistance to screw withdrawal. The panels produced with vassoura particle absorbed more water and, consequently, increased the thickness swelling, and therefore is not recommended for use in environments with high humidity. It was concluded that the genus Sida, in general, has potential for particleboard production.

  2. Effect of Particle Size on Microstructure and Mechanical Properties of Al-Based Composite Reinforced with 10 Vol.% Mechanically Alloyed Mg-7.4%Al Particles

    Directory of Open Access Journals (Sweden)

    Anil K. Chaubey

    2016-11-01

    Full Text Available The effect of Mg-7.4%Al reinforcement particle size on the microstructure and mechanical properties in pure Al matrix composites was investigated. The samples were prepared by hot consolidation using 10 vol.% reinforcement in different size ranges, D, 0 < D < 20 µm (0–20 µm, 20 ≤ D < 40 µm (20–40 µm, 40 ≤ D < 80 µm (40–80 µm and 80 ≤ D < 100 µm (80–100 µm. The result reveals that particle size has a strong influence on the yield strength, ultimate tensile strength and percentage elongation. As the particle size decreases from 80 ≤ D < 100 µm to 0 < D < 20 µm, both tensile strength and ductility increases from 195 MPa to 295 MPa and 3% to 4% respectively, due to the reduced ligament size and particle fracturing. Wear test results also corroborate the size effect, where accelerated wear is observed in the composite samples reinforced with coarse particles.

  3. Preparation of SnO_2-Glass Composite Containing Cu Particles Reduced from Copper Ions in Glass Matrix : Effect of Glass Particle Size on Microstructure and Electrical Property

    OpenAIRE

    Haruhisa, SHIOMI; Kaori, UMEHARA; Faculty of Engineering and Design, Kyoto Institute of Technology; Faculty of Engineering and Design, Kyoto Institute of Technology

    2000-01-01

    An attempt was made to improve the electrical properties of SnO_2-glass composites by dispersing Cu particles with low resistivity and positive temperature coefficient of resistance(TCR)in the glass matrix. Cu metal particles were precipitated by reducing Cu_2O previously dissolved into the matrix glass by adding LaB_6 as a reducing agent. The effect of the glass particle size, which influences the homogeneity of LaB_6 dispersion in the powder mixture before firing, on the Cu precipitation in...

  4. A critical look at 50 years particle theory from the perspective of the crossing property

    International Nuclear Information System (INIS)

    Schroer, Bert; Freie Universitaet, Berlin

    2010-02-01

    The crossing property, which originated more than 5 decades ago in the aftermath of dispersion relations, was the central new concept which opened an S-matrix based line of research in particle theory. Many constructive ideas in particle theory outside perturbative QFT, among them the S-matrix bootstrap program, the dual resonance model and the various stages of string theory have their historical roots in this property. The crossing property is perhaps the most subtle aspect of the particle-field relation. Although it is not difficult to state its content in terms of certain analytic properties relating different matrix elements of the S-matrix or form factors, its relation to the localization- and positive energy spectral principles requires a level of insight into the inner workings of QFT which goes beyond anything which can be found in typical textbooks on QFT. This paper presents a recent account based on new ideas derived from 'modular localization' including a mathematic appendix on this subject. The main content is an in-depth criticism of the dual model and its string theoretic extension. The conceptual flaws of these models are closely related to misunderstandings of the true meaning of crossing. The correct interpretation of string theory is that of a dynamic infinite component wave function or pointlike field i.e. a theory which under irreducible Poincare decomposition into an infinite mass/spin tower but which also contains operators which do not commute with the generators of the Poincare group but rather intertwine between different mass/spin levels. (author)

  5. A critical look at 50 years particle theory from the perspective of the crossing property

    Energy Technology Data Exchange (ETDEWEB)

    Schroer, Bert [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Freie Universitaet, Berlin (Germany). Inst. fuer Theoretische Physik

    2010-02-15

    The crossing property, which originated more than 5 decades ago in the aftermath of dispersion relations, was the central new concept which opened an S-matrix based line of research in particle theory. Many constructive ideas in particle theory outside perturbative QFT, among them the S-matrix bootstrap program, the dual resonance model and the various stages of string theory have their historical roots in this property. The crossing property is perhaps the most subtle aspect of the particle-field relation. Although it is not difficult to state its content in terms of certain analytic properties relating different matrix elements of the S-matrix or form factors, its relation to the localization- and positive energy spectral principles requires a level of insight into the inner workings of QFT which goes beyond anything which can be found in typical textbooks on QFT. This paper presents a recent account based on new ideas derived from 'modular localization' including a mathematic appendix on this subject. The main content is an in-depth criticism of the dual model and its string theoretic extension. The conceptual flaws of these models are closely related to misunderstandings of the true meaning of crossing. The correct interpretation of string theory is that of a dynamic infinite component wave function or pointlike field i.e. a theory which under irreducible Poincare decomposition into an infinite mass/spin tower but which also contains operators which do not commute with the generators of the Poincare group but rather intertwine between different mass/spin levels. (author)

  6. Shear jamming: where does it come from and how is it affected by particle properties?

    Science.gov (United States)

    Wang, Dong

    Granular systems have been shown to be able to behave like solids, under shear, even when their densities are below the critical packing fraction for frictionless isotropic jamming. To understand such a phenomena, called shear jamming, the questions we address here is: how does shear bring a system from a unjammed state to a jammed state and how do particle properties, such as inter-particle friction and particle shape, affect shear jamming? Since Z can be used to distinguish jammed states from unjammed ones (Z = 3 is the isotropic jamming point for 2 D frictional disks), it is vital to understand how shear increases Z. In the first part of this talk, we propose a set of three particles in contact, denoted as a trimer, as the basic unit to microscopically characterize the deformation of the system. Trimers, stabilized by inter-grain friction, are then expected to bend in response to shear to make extra contacts to regain stability. By defining a projection operator of the opening angle of the trimer to the compression direction in the shear, O, we see a systematically linear decrease of this quantity with respect to shear strain, demonstrating the bending of trimers as expected. In the second part of this talk, we look into the effect of particle properties on shear jamming. Photoelastic disks either wrapped with Teflon to reduce friction or with fine teeth on the edge to increase friction are used to study the effect of friction. In addition, disks are replaced with ellipses to introduce anisotropy into the particle shape. Shear jamming is observed for all the cases. For the disk system, the lowest packing fraction that can reach a shear jammed state increases with friction. For the ellipse system, shear brings the system to a more ordered state and particles tend to align to a certain angle relative to the principal directions of shear, regardless of packing fraction. Support by NSF DMR1206351, NASA NNX15AD38G, the W. M. Keck Foundation and a Triangle MRSEC

  7. Microphysical Properties of Frozen Particles Inferred from Global Precipitation Measurement (GPM) Microwave Imager (GMI) Polarimetric Measurements

    Science.gov (United States)

    Gong, Jie; Wu, Dongliang

    2017-01-01

    Scattering differences induced by frozen particle microphysical properties are investigated, using the vertically (V) and horizontally (H) polarized radiances from the Global Precipitation Measurement (GPM) Microwave Imager (GMI) 89 and 166GHz channels. It is the first study on global frozen particle microphysical properties that uses the dual-frequency microwave polarimetric signals. From the ice cloud scenes identified by the 183.3 3GHz channel brightness temperature (TB), we find that the scatterings of frozen particles are highly polarized with V-H polarimetric differences (PD) being positive throughout the tropics and the winter hemisphere mid-latitude jet regions, including PDs from the GMI 89 and 166GHz TBs, as well as the PD at 640GHz from the ER-2 Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) during the TC4 campaign. Large polarization dominantly occurs mostly near convective outflow region (i.e., anvils or stratiform precipitation), while the polarization signal is small inside deep convective cores as well as at the remote cirrus region. Neglecting the polarimetric signal would result in as large as 30 error in ice water path retrievals. There is a universal bell-curve in the PD TB relationship, where the PD amplitude peaks at 10K for all three channels in the tropics and increases slightly with latitude. Moreover, the 166GHz PD tends to increase in the case where a melting layer is beneath the frozen particles aloft in the atmosphere, while 89GHz PD is less sensitive than 166GHz to the melting layer. This property creates a unique PD feature for the identification of the melting layer and stratiform rain with passive sensors. Horizontally oriented non-spherical frozen particles are thought to produce the observed PD because of different ice scattering properties in the V and H polarizations. On the other hand, changes in the ice microphysical habitats or orientation due to turbulence mixing can also lead to a reduced PD in the deep

  8. Light scattering and absorption properties of dust particles retrieved from satellite measurements

    International Nuclear Information System (INIS)

    Hu, R.-M.; Sokhi, R.S.

    2009-01-01

    We use the radiative transfer model and chemistry transport model to improve our retrievals of dust optical properties from satellite measurements. The optical depth and absorbing optical depth of mineral dust can be obtained from our improved retrieval algorithm. We find the nonsphericity and absorption of dust particles strongly affect the scattering signatures such as phase function and polarization at the ultraviolet wavelengths. From our retrieval results, we find the high levels of dust concentration occurred over most desert regions such as Saharan and Gobi deserts. The dust absorption is found to be sensitive to mineral chemical composition, particularly the fraction of strongly absorbing dust particles. The enhancement of polarization at the scattering angles exceeding 120 0 is found for the nonspherical dust particles. If the polarization is neglected in the radiative transfer calculation, a maximum 50 percent error is introduced for the case of forward scattering and 25 percent error for the case of backscattering. We suggest that the application of polarimeter at the ultraviolet wavelengths has the great potential to improve the satellite retrievals of dust properties. Using refined optical model and radiative transfer model to calculate the solar radiative forcing of dust aerosols can reduce the uncertainties in aerosol radiative forcing assessment.

  9. Microwave absorbing property of silicone rubber composites with added carbonyl iron particles and graphite platelet

    International Nuclear Information System (INIS)

    Xu, Yonggang; Zhang, Deyuan; Cai, Jun; Yuan, Liming; Zhang, Wenqiang

    2013-01-01

    Silicone rubber composites filled with carbonyl iron particles (CIPs) and graphite platelet (GP) were prepared using non-coating or coating processes. The complex permittivity and permeability of the composites were measured using a vector network analyzer in the frequency range of 1–18 GHz and dc electric conductivity was measured by the standard four-point contact method. The results showed that CIPs/GP composites fabricated in the coating process had the highest permittivity and permeability due to the particle orientation and interactions between the two absorbents. The coating process resulted in a decreased effective eccentricity of the absorbents, and the dc conductivity increased according to Neelakanta's equations. The reflection loss (RL) value showed that the composites had an excellent absorbing property in the L-band, minimum −11.85 dB at 1.5 mm and −15.02 dB at 2 mm. Thus, GP could be an effective additive in preparing thin absorbing composites in the L-band. - Highlights: ► The added GP increased the permittivity and permeability of composites filled with CIPs. ► The enhancement was owing to interactions of the two absorbents and the fabrication process. ► The coating process decreased the effective eccentricity of the particles, and increased the conductivity of the composites. ► The composites to which CIPs/GP were added in coating process had excellent absorbing properties in the L-band.

  10. The effects of particle properties on nanoparticle drug retention and release in dynamic minoxidil foams.

    Science.gov (United States)

    Zhao, Yanjun; Brown, Marc B; Jones, Stuart A

    2010-01-04

    Nanocarriers may act as useful tools to deliver therapeutic agents to the skin. However, balancing the drug-particle interactions; to ensure adequate drug loading, with the drug-vehicle interactions; to allow efficient drug release, presents a significant challenge using traditional semi-solid vehicles. The aim of this study was to determine how the physicochemical properties of nanoparticles influenced minoxidil release pre and post dose application when formulated as a simple aqueous suspension compared to dynamic hydrofluoroalkane (HFA) foams. Minoxidil loaded lipid nanoparticles (LN, 1.4 mg/ml, 50 nm) and polymeric nanoparticles with a lipid core (PN, 0.6 mg/ml, 260 nm) were produced and suspended in water to produce the aqueous suspensions. These aqueous suspensions were emulsified with HFA using pluronic surfactant to generate the foams. Approximately 60% of the minoxidil loaded into the PN and 80% of the minoxidil loaded into the LN was released into the external aqueous phase 24h after production. Drug permeation was superior from the PN, i.e. it was the particle that retained the most drugs, irrespective of the formulation method. Premature drug release, i.e. during storage, resulted in the performance of the topical formulation being dictated by the thermodynamic activity of the solubilised drug not the particle properties.

  11. Modifications of the optical properties for DAM-ADC nuclear track detector exposed to alpha particles

    Science.gov (United States)

    Rammah, Y. S.; Awad, E. M.

    2018-05-01

    Modifications of the optical properties of diallyl maleate-allyl diglycol carbonate (DAM-ADC) nuclear detector induced by alpha particles are described. DAM-ADC samples were irradiated perpendicularly by thin 241Am disk source that emits alpha particles with 5.48 MeV. The optical absorption has been measured using the ultraviolet-visible (UV-1100) spectroscopy. It was found that DAM-ADC polymer shows substantial modifications in its optical characteristics upon irradiated with alpha particles with different energies. The optical energy band gap (Egap) for the detector was calculated for the direct and the indirect allowed transitions in K-space using two approaches (Tauc's model and absorption spectrum fitting (ASF) method). Urbach's energy (Ea), number of carbon atoms per conjugated length (N), number of carbon atoms per cluster (M), and refractive index (n) for the present samples were determined. Results reveal that the values of energy gap in direct transition are greater than those of indirect, before and after irradiation. (Egap), (Ea), (N), (M), and (n) of the present samples are changed significantly with irradiation time and value of alpha energy. Results reflect the possibility of using DAM-ADC polymer track detectors to estimate alpha particle energies using the variation of the absorbance.

  12. Effect of Wheat Straw Pretreatments and Glue Formulations on particle board properties

    International Nuclear Information System (INIS)

    Jabeen, S.; Naveed, S.; Yousaf, S.; Ramzan, N.

    2014-01-01

    In this paper, the effect of wheat straw (WS) pretreatments and glue formulations on mechanical (i.e. Compressive Strength (CS) and Impact Strength (IS)) and water resistance properties (i.e. Thickness Swelling (TS) and water absorption (WA)) of particle board have been investigated and the results have been compared with conventional wooden particleboard. Wheat straw was treated with steam available at 110 degree C and 20 psig, for the retention time of 5, 10 and 15 min. The solution of 10% HCl was also used for removing the lignin. Particleboard was prepared by bonding treated WS with four types of glue recipes of synthetic and natural binders like urea formaldehyde (UF), polyvinyl acetate (PVA), corn flour (CF) and wheat flour (WF). The particle board was formed at the hydraulic pressure and temperature of 2800 psig and 80 degree C respectively. It was observed that WS particleboard has low mechanical strength and high water resistance in comparison with conventional board. The particle board prepared with HCl cured wheat straw and glue having high urea formaldehyde and corn flour has higher CS and IS as well as low TS and WA. It may be concluded that wheat straw is a good substitute of wood for particle board while using HCl as a modifying chemical and strong binders like urea formaldehyde and corn flour. (author)

  13. Simulation study on the structural properties of colloidal particles with offset dipoles.

    Science.gov (United States)

    Rutkowski, David M; Velev, Orlin D; Klapp, Sabine H L; Hall, Carol K

    2017-05-03

    A major research theme in materials science is determining how the self-assembly of new generations of colloidal particles of complex shape and surface charge is guided by their interparticle interactions. In this paper, we describe results from quasi-2D Monte Carlo simulations of systems of colloidal particles with offset transversely-oriented extended dipole-like charge distributions interacting via an intermediate-ranged Yukawa potential. The systems are cooled slowly through an annealing procedure during which the temperature is lowered in discrete steps, allowing the system to equilibrate. We perform ground state calculations for two, three and four particles at several shifts of the dipole vector from the particle center. We create state diagrams in the plane spanned by the temperature and the area fraction outlining the boundaries between fluid, string-fluid and percolated states at various values of the shift. Remarkably we find that the effective cooling rate in our simulations has an impact on the structures formed, with chains being more prevalent if the system is cooled quickly and cyclic structures more prevalent if the system is cooled slowly. As the dipole is further shifted from the center, there is an increased tendency to assemble into small cyclic structures at intermediate temperatures. These systems further self-assemble into open lattice-like arrangements at very low temperatures. The novel structures identified might be useful for photonic applications, new types of porous media for filtration and catalysis, and gel matrices with unusual properties.

  14. Analysis of Physical and Mechanical Properties of Marble Particles Floor-Tile Composite

    International Nuclear Information System (INIS)

    Parikin; Arslan, A.; Ismoyo, A.H.; Jodi, H.E.; Nurhasanah, S.

    2002-01-01

    Two criteria that very predictable to quality products of marble particles composite floor-tile are physical and mechanical properties. Simple manufacturing was conducted from powdering refuges of marble to molding and drying the specimens at ambient atmosphere. The characterization, to observe; density, crystal structure, microstructure, hardness and compressive/bending strength of the material, was performed in Serpong and IPB-Bogor. The analysis shows that polymeric crystallization was occurred by HEXA and the density and the hardness generally rise up with the improvements in mesh and composition of marble particles. But it is not always followed by the real improvements of compressive and bending strength, which related to the material stiffness. The curves figured that these two strengths give the maximum values at 60% composition of marble particles. It can be concluded that density and hardness are dependent on mesh and composition, whereas the stiffness (modulus) is only correlation with composition of particulate. The theoretical modulus of marble particles composite floor-tile has been evaluated at about 56.19 GPa. (author)

  15. Structure organization and magnetic properties of microscale ferrogels: The effect of particle magnetic anisotropy

    Science.gov (United States)

    Ryzhkov, Aleksandr V.; Melenev, Petr V.; Balasoiu, Maria; Raikher, Yuriy L.

    2016-08-01

    The equilibrium structure and magnetic properties of a ferrogel object of small size (microferrogel(MFG)) are investigated by coarse-grained molecular dynamics. As a generic model of a microferrogel (MFG), a sample with a lattice-like mesh is taken. The solid phase of the MFG consists of magnetic (e.g., ferrite) nanoparticles which are mechanically linked to the mesh making some part of its nodes. Unlike previous models, the finite uniaxial magnetic anisotropy of the particles, as it is the case for real ferrogels, is taken into account. For comparison, two types of MFGs are considered: MFG-1, which dwells in virtually non-aggregated state independently of the presence of an external magnetic field, and MFG-2, which displays aggregation yet under zero field. The structure states of the samples are analyzed with the aid of angle-resolved radial distribution functions and cluster counts. The results reveal the crucial role of the matrix elasticity on the structure organization as well as on magnetization of both MFGs. The particle anisotropy, which plays insignificant role in MFG-1 (moderate interparticle magnetodipole interaction), becomes an important factor in MFG-2 (strong interaction). There, the restrictions imposed on the particle angular freedom by the elastic matrix result in notable diminution of the particle chain lengths as well as the magnetization of the sample. The approach proposed enables one to investigate a large variety of MFGs, including those of capsule type and to purposefully choose the combination of their magnetoelastic parameters.

  16. Ambient black carbon particle hygroscopic properties controlled by mixing state and composition

    Directory of Open Access Journals (Sweden)

    D. Liu

    2013-02-01

    Full Text Available The wet removal of black carbon aerosol (BC in the atmosphere is a crucial factor in determining its atmospheric lifetime and thereby the vertical and horizontal distributions, dispersion on local and regional scales, and the direct, semi-direct and indirect radiative forcing effects. The in-cloud scavenging and wet deposition rate of freshly emitted hydrophobic BC will be increased on acquisition of more-hydrophilic components by coagulation or coating processes. The lifetime of BC is still subject to considerable uncertainty for most of the model inputs, which is largely due to the insufficient constraints on the BC hydrophobic-to-hydrophilic conversion process from observational field data. This study was conducted at a site along UK North Norfolk coastline, where the BC particles were transported from different regions within Western Europe. A hygroscopicity tandem differential mobility analyser (HTDMA was coupled with a single particle soot photometer (SP2 to measure the hygroscopic properties of BC particles and associated mixing state in real time. In addition, a Soot Particle AMS (SP-AMS measured the chemical compositions of additional material associated with BC particles. The ensemble of BC particles persistently contained a less-hygroscopic mode at a growth factor (gf of around 1.05 at 90% RH (dry diameter 163 nm. Importantly, a more-hygroscopic mode of BC particles was observed throughout the experiment, the gf of these BC particles extended up to ~1.4–1.6 with the minimum between this and the less hygroscopic mode at a gf ~1.25, or equivalent effective hygroscopicity parameter κ ~0.1. The gf of BC particles (gfBC was highly influenced by the composition of associated soluble material: increases of gfBC were associated with secondary inorganic components, and these increases were more pronounced when ammonium nitrate was in the BC particles; however the presence of secondary organic matter suppressed

  17. The relationship between the particle properties, mechanical behavior, and surface roughness of some pharmaceutical excipient compacts

    International Nuclear Information System (INIS)

    Narayan, Padma; Hancock, Bruno C.

    2003-01-01

    Several common pharmaceutical excipient powders were compacted at a constant solid fraction (SF) in order to study the relationship between powder properties, compact surface roughness, and compact mechanical properties such as hardness, elasticity, and brittleness. The materials used in this study included microcrystalline cellulose (MCC), fumaric acid, mannitol, lactose monohydrate, spray dried lactose, sucrose, and dibasic calcium phosphate dihydrate. A slow consolidation process was used to make compacts at a SF of 0.85 (typical for most pharmaceutical tablets) from single excipient components. A model was proposed to describe the surface roughness of compacts based on the brittle or ductile deformation tendencies of the powder materials. The roughness profile would also be dependent upon the magnitude of the compression stress in relation to the yield stress (onset of irreversible deformation) values of the excipients. It was hypothesized that brittle materials would produce smooth compacts with high surface variability due to particle fracture, and the converse would apply for ductile materials. Compact surfaces should be smoother if the materials were compressed above their yield pressure values. Non-contact optical profilometry was used along with scanning electron microscopy to quantify and characterize the surface morphology of the excipient compacts. The roughness parameters R a (average roughness), R q (RMS roughness), R q /R a (ratio describing surface variability), and R sk (skewness) were found to correlate with the deformation properties of the excipients. Brittle materials such as lactose, sucrose, and calcium phosphate produced compacts with low values of R a and R q , high variability, and negative R sk . The opposite was found with plastic materials such as MCC, mannitol, and fumaric acid. The highly negative skewness values for brittle material compacts may indicate their propensity to be vulnerable to cracks or surface defects. These findings

  18. The relationship between the particle properties, mechanical behavior, and surface roughness of some pharmaceutical excipient compacts

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Padma; Hancock, Bruno C

    2003-08-25

    Several common pharmaceutical excipient powders were compacted at a constant solid fraction (SF) in order to study the relationship between powder properties, compact surface roughness, and compact mechanical properties such as hardness, elasticity, and brittleness. The materials used in this study included microcrystalline cellulose (MCC), fumaric acid, mannitol, lactose monohydrate, spray dried lactose, sucrose, and dibasic calcium phosphate dihydrate. A slow consolidation process was used to make compacts at a SF of 0.85 (typical for most pharmaceutical tablets) from single excipient components. A model was proposed to describe the surface roughness of compacts based on the brittle or ductile deformation tendencies of the powder materials. The roughness profile would also be dependent upon the magnitude of the compression stress in relation to the yield stress (onset of irreversible deformation) values of the excipients. It was hypothesized that brittle materials would produce smooth compacts with high surface variability due to particle fracture, and the converse would apply for ductile materials. Compact surfaces should be smoother if the materials were compressed above their yield pressure values. Non-contact optical profilometry was used along with scanning electron microscopy to quantify and characterize the surface morphology of the excipient compacts. The roughness parameters R{sub a} (average roughness), R{sub q} (RMS roughness), R{sub q}/R{sub a} (ratio describing surface variability), and R{sub sk} (skewness) were found to correlate with the deformation properties of the excipients. Brittle materials such as lactose, sucrose, and calcium phosphate produced compacts with low values of R{sub a} and R{sub q}, high variability, and negative R{sub sk}. The opposite was found with plastic materials such as MCC, mannitol, and fumaric acid. The highly negative skewness values for brittle material compacts may indicate their propensity to be vulnerable to

  19. Theoretical analysis of the particle properties and polarization measurements made in microgravity

    International Nuclear Information System (INIS)

    Penttilae, A.; Lumme, K.; Worms, J.C.; Hadamcik, E.; Renard, J.B.; Levasseur-Regourd, A.C.

    2003-01-01

    We propose a new model to describe the shapes of stochastic polyhedra used in the microgravity experiment PROGRA 2 on board the Airbus A300 aircraft. The polarization measurements of scattering of visible light by boron carbide (B 4 C) particles with sizes between 9 and 88 μm can nicely be explained with the derived shape statistics and the (currently unknown) refractive index obtained. For the latter we derive 2 (-0.15/+0.1)+0.04i(-0.0025/+0.015) at 632.8 nm wavelength. The polarization method is a reliable and sensitive means to estimate various particle properties in various remote sensing applications, including the planetary sciences

  20. Theoretical analysis of the particle properties and polarization measurements made in microgravity

    CERN Document Server

    Penttilae, A; Worms, J C; Hadamcik, E; Renard, J B; Levasseur-Regourd, A C

    2003-01-01

    We propose a new model to describe the shapes of stochastic polyhedra used in the microgravity experiment PROGRA sup 2 on board the Airbus A300 aircraft. The polarization measurements of scattering of visible light by boron carbide (B sub 4 C) particles with sizes between 9 and 88 mu m can nicely be explained with the derived shape statistics and the (currently unknown) refractive index obtained. For the latter we derive 2 (-0.15/+0.1)+0.04i(-0.0025/+0.015) at 632.8 nm wavelength. The polarization method is a reliable and sensitive means to estimate various particle properties in various remote sensing applications, including the planetary sciences.

  1. Iron particle and anisotropic effects on mechanical properties of magneto-sensitive elastomers

    Science.gov (United States)

    Kumar, Vineet; Lee, Dong-Joo

    2017-11-01

    Rubber specimens were prepared by mixing micron-sized iron particles dispersed in room-temperature-vulcanized (RTV) silicone rubber by solution mixing. The possible correlations of the particle volume, size, and distribution with the mechanical properties of the specimens were examined. An isotropic mechanical test shows that at 60 phr, the elastic modulus was 3.29 MPa (electrolyte), 2.92 MPa (carbonyl), and 2.61 MPa (hybrid). The anisotropic effect was examined by curing the specimen under magnetic fields of 0.5-2.0 T at 90° relative to the applied strain. The measurements show anisotropic effects of 11% (carbonyl), 9% (electrolyte), and 6% (hybrid) at 40 phr and 1 T. At 80 phr, the polymer-filler compatibility factor (c-factor) was estimated using the Pythagorean theorem as 0.53 (regular) and 0.73 (anisotropic studies). The improved features could be useful in applications such as controlled damping, vibrational absorption, or automotive bushings.

  2. First correlated measurements of the shape and light scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS probe

    Directory of Open Access Journals (Sweden)

    A. Abdelmonem

    2011-10-01

    Full Text Available Studying the radiative impact of cirrus clouds requires knowledge of the relationship between their microphysics and the single scattering properties of cloud particles. Usually, this relationship is obtained by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS designed to measure simultaneously the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles. Clouds containing particles ranging from a few micrometers to about 800 μm diameter in size can be characterized systematically with an optical resolution power of 2 μm and polar scattering resolution of 1° for forward scattering directions (from 1° to 10° and 8° for side and backscattering directions (from 18° to 170°. The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced size distributions and images comparable to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF program. PHIPS is a highly promising novel airborne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurement instruments.

  3. First correlated measurements of the shape and scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS) probe

    Science.gov (United States)

    Abdelmonem, A.; Schnaiter, M.; Amsler, P.; Hesse, E.; Meyer, J.; Leisner, T.

    2011-05-01

    Studying the radiative impact of cirrus clouds requires the knowledge of the link between their microphysics and the single scattering properties of the cloud particles. Usually, this link is created by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS) designed to measure the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles, simultaneously. Clouds containing particles ranging in size from a few micrometers to about 800 μm diameter can be systematically characterized with an optical resolution power of 2 μm and polar scattering resolution of 1° for forward scattering directions (from 1° to 10°) and 8° for side and backscattering directions (from 18° to 170°). The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns which were conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced comparable size distributions and images to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF) program. PHIPS is candidate to be a novel air borne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurements instruments.

  4. First correlated measurements of the shape and light scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS) probe

    Science.gov (United States)

    Abdelmonem, A.; Schnaiter, M.; Amsler, P.; Hesse, E.; Meyer, J.; Leisner, T.

    2011-10-01

    Studying the radiative impact of cirrus clouds requires knowledge of the relationship between their microphysics and the single scattering properties of cloud particles. Usually, this relationship is obtained by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS) designed to measure simultaneously the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles. Clouds containing particles ranging from a few micrometers to about 800 μm diameter in size can be characterized systematically with an optical resolution power of 2 μm and polar scattering resolution of 1° for forward scattering directions (from 1° to 10°) and 8° for side and backscattering directions (from 18° to 170°). The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced size distributions and images comparable to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF) program. PHIPS is a highly promising novel airborne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurement instruments.

  5. An Analytical Approach for Fast Recovery of the LSI Properties in Magnetic Particle Imaging

    Directory of Open Access Journals (Sweden)

    Hamed Jabbari Asl

    2016-01-01

    Full Text Available Linearity and shift invariance (LSI characteristics of magnetic particle imaging (MPI are important properties for quantitative medical diagnosis applications. The MPI image equations have been theoretically shown to exhibit LSI; however, in practice, the necessary filtering action removes the first harmonic information, which destroys the LSI characteristics. This lost information can be constant in the x-space reconstruction method. Available recovery algorithms, which are based on signal matching of multiple partial field of views (pFOVs, require much processing time and a priori information at the start of imaging. In this paper, a fast analytical recovery algorithm is proposed to restore the LSI properties of the x-space MPI images, representable as an image of discrete concentrations of magnetic material. The method utilizes the one-dimensional (1D x-space imaging kernel and properties of the image and lost image equations. The approach does not require overlapping of pFOVs, and its complexity depends only on a small-sized system of linear equations; therefore, it can reduce the processing time. Moreover, the algorithm only needs a priori information which can be obtained at one imaging process. Considering different particle distributions, several simulations are conducted, and results of 1D and 2D imaging demonstrate the effectiveness of the proposed approach.

  6. Effects of particle shape and size on nanofluid properties for potential Enhanced Oil Recovery (EOR

    Directory of Open Access Journals (Sweden)

    Tengku Mohd Tengku Amran

    2016-01-01

    Full Text Available Application of Enhanced Oil Recovery (EOR in oil and gas industry is very important to increase oil recovery and prolong the lifetime of a reservoir but it has been very costly and losing properties of EOR agent due to harsh condition. Nanoparticles have been used in EOR application since they are not degradable in reservoir condition and used in smaller amount compared to polymer usage. Commonly, EOR techniques are focusing on increasing the sweep efficiency by controlling the mobility ratio between reservoir fluid and injected fluid. Thus, this research aimed to analyze the nanofluid viscosity at different particle size and shape, volumetric concentration and types of dispersing fluid, as well as to determine the oil recovery performance at different nanofluid concentration. The nanofluid viscosity was investigated at nanoparticle sizes of 15nm and 60nm and shapes of 15nm spherical-solid and porous. Five nanofluid samples with concentration ranging from 0.1wt.% to 7wt.% were used to investigate the effect of volumetric concentration. Distilled water, ethanol, ethylene glycol (EG and brine were used for the effect of dispersing fluids. Oil recovery was investigated at five different concentrations of nanofluid samples through flooding test. It was found that viscosity of nanofluid increased with decreasing particle size and increasing volumetric concentration. Solid shape particle and increasing dispersing fluid viscosity resulted in higher nanofluid viscosity. The higher the nanofluid concentration, the higher the oil recovery obtained. It can be concluded that nanofluid properties have been significantly affected by the environment and the particle used for potential EOR application.

  7. The mechanical properties of nanofilled resin-based composites: characterizing discrete filler particles and agglomerates using a micromanipulation technique.

    LENUS (Irish Health Repository)

    Curtis, Andrew R

    2009-02-01

    To assess the mechanical properties of discrete filler particles representative of several inorganic fillers in modern dental resin-based composites (RBCs) and to assess the validity of a novel micromanipulation technique.

  8. Mechanical Properties and Structures of Pyrolytic Carbon Coating Layer in HTR Coated Particle Fuel

    International Nuclear Information System (INIS)

    Lee, Young Woo; Kim, Young Min; Kim, Woong Ki; Cho, Moon Sung

    2009-01-01

    The TRISO(tri-isotropic)-coated fuel particle for a HTR(High Temperature gas-cooled Reactor) has a diameter of about 1 mm, composed of a nuclear fuel kernel and four different outer coating layers, consisting of a buffer PyC (pyrolytic carbon) layer, inner PyC layer, SiC layer, and outer PyC layer with different coating thicknesses following a specific fuel design. While the fuel kernel is a source for a heat generation by a nuclear fission of fissile uranium, each of the four coating layers acts as a different role in view of retaining the generated fission products and the other interactions during an in-reactor service. Among these coating layers, PyC properties are scarcely in agreement among various investigators and the dependency of their changes upon the deposition condition is comparatively large due to their additional anisotropic properties. Although a recent review work has contributed to an establishment of relationship between the material properties and QC measurements, the data on the mechanical properties and structural parameters of PyC coating layers remain still unclearly evaluated. A review work on dimensional changes of PyC by neutron irradiation was one of re-evaluative works recently attempted by the authors. In this work, an attempt was made to analyze and re-evaluate the existing data of the experimental results of the mechanical properties, i.e., Young's modulus and fracture stress, in relation with the coating conditions, density and the BAF (Bacon Anisotropy Factor), an important structural parameter, of PyC coating layers obtained from various experiments performed in the early periods of the HTR coated particle development

  9. Size effect of added LaB6 particles on optical properties of LaB6/Polymer composites

    International Nuclear Information System (INIS)

    Yuan Yifei; Zhang Lin; Hu Lijie; Wang Wei; Min Guanghui

    2011-01-01

    Modified LaB 6 particles with sizes ranging from 50 nm to 400 nm were added into polymethyl methacrylate (PMMA) matrix in order to investigate the effect of added LaB 6 particles on optical properties of LaB 6 /PMMA composites. Method of in-situ polymerization was applied to prepare PMMA from raw material—methyl methacrylate (MMA), a process during which LaB 6 particles were dispersed in MMA. Ultraviolet–visible–near infrared (UV–vis–NIR) absorption spectrum was used to study optical properties of the as-prepared materials. The difference in particle size could apparently affect the composites' absorption of visible light around wavelength of 600 nm. Added LaB 6 particles with size of about 70 nm resulted in the best optical properties among these groups of composites. - Graphical abstract: 70 nm LaB 6 particles resulted in the best performance on absorption of VIS and NIR, which could not be apparently achieved by LaB 6 particles beyond nano-scale. Highlights: ► LaB 6 /PMMA composites were prepared using the method of in-situ polymerization. ► LaB 6 particles added in MMA prolonged the time needed for its pre-polymerization. ► Nanosized LaB 6 particles could obviously absorb much NIR but little VIS.

  10. Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

    International Nuclear Information System (INIS)

    Zhang, Dongya; Dong, Guangneng; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-01

    Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm 2 for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

  11. Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere

    Directory of Open Access Journals (Sweden)

    A. Wonaschütz

    2013-10-01

    Full Text Available During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE, a plume of organic aerosol was produced by a smoke generator and emitted into the marine atmosphere from aboard the R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, the plume particles had very low hygroscopic growth factors (GFs: between 1.05 and 1.09 for 30 nm and between 1.02 and 1.1 for 150 nm dry size at a relative humidity (RH of 92%, contrasted by an average marine background GF of 1.6. New particles were produced in large quantities (several 10 000 cm−3, which lead to substantially increased cloud condensation nuclei (CCN concentrations at supersaturations between 0.07 and 0.88%. Ratios of oxygen to carbon (O : C and water-soluble organic mass (WSOM increased with plume age: from −3, respectively, while organic mass fractions decreased slightly (~ 0.97 to ~ 0.94. High-resolution aerosol mass spectrometer (AMS spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small, new particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions: an average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, and a GF of 1.04 for an organic mass fraction of 0.35.

  12. Cellular uptake of nanoparticles as determined by particle properties, experimental conditions, and cell type.

    Science.gov (United States)

    Kettler, Katja; Veltman, Karin; van de Meent, Dik; van Wezel, Annemarie; Hendriks, A Jan

    2014-03-01

    The increased application of nanoparticles (NPs) is increasing the risk of their release into the environment. Although many toxicity studies have been conducted, the environmental risk is difficult to estimate, because uptake mechanisms are often not determined in toxicity studies. In the present study, the authors review dominant uptake mechanisms of NPs in cells, as well as the effect of NP properties, experimental conditions, and cell type on NP uptake. Knowledge of NP uptake is crucial for risk assessment and is essential to predict the behavior of NPs based on their physical-chemical properties. Important uptake mechanisms for eukaryotic cells are macropinocytosis, receptor-mediated endocytosis, and phagocytosis in specialized mammalian cells. The studies reviewed demonstrate that uptake into nonphagocytic cells depends strongly on NP size, with an uptake optimum at an NP diameter of approximately 50 nm. Increasing surface charges, either positive or negative, have been shown to increase particle uptake in comparison with uncharged NPs. Another important factor is the degree of (homo-) aggregation. Results regarding shape have been ambiguous. Difficulties in the production of NPs, with 1 property changed at a time, call for a full characterization of NP properties. Only then will it be possible to draw conclusions as to which property affected the uptake. © 2013 SETAC.

  13. The Use Of Optical Properties Of Cr-39 In Alpha Particle Equivalent Dose Measurements

    International Nuclear Information System (INIS)

    Shnishin, K.A.

    2007-01-01

    In this work, optical properties of alpha irradiated Cr-39 were measured as a function of optical photon wavelength from 200-1100 nm. Optical energy gap and optical absorption at finite wavelength was also calculated and correlated to alpha fluence and dose equivalent. Alpha doses were calculated from the corresponding irradiation fluence and specific energy loss using TRIM computer program. It was found that, the optical absorption of unattached Cr-39 was varied with alpha fluence and corresponding equivalent doses. Also the optical energy gab was varied with fluence and dose equivalent of alpha particles. This work introduces a reasonably simple method for the Rn dose equivalent calculation by Cr-39 track

  14. Pairing and low temperature properties of 2 D Fermi-systems with attraction between particles

    International Nuclear Information System (INIS)

    Gorbar, E.V.; Gusynin, V.P.; Loktev, V.M.

    1992-01-01

    Proceeding from microscopic model Hamiltonian for the system of Fermi-particles with attraction the effective Lagrangian, admitting the analysis of its superconducting properties at arbitrary fermion concentration, is obtained.Exact solution for gap and chemical potential makes it possible to trace from local pair situation to Cooper pairing. The crucial parameter discriminating between the regions of exotic and normal superconducting behaviour is show to be that of the energy of the bound fermion state, which, however, rapidly disappears with fermion density increasing. The solutions of the equations for the case of finite temperatures are analysed. (author). 42 refs

  15. Nuclear matter with a pseudo-particle model: static bulk and surface properties

    International Nuclear Information System (INIS)

    Idier, D.; Benhassine, B.; Farine, M.; Remaud, B.; Sebille, F.

    1993-01-01

    Direct calculations of cold and hot nuclear matter (bulk and surface properties) are carried out within the frame of a pseudo-particle model using a gaussian decomposition of the distribution function. Comparisons with Hartree-Fock calculations, for a large class of effective interactions, show that such a model is reliable to reproduce accurately the equation of state of nuclear matter for large ranges of densities and temperatures. The number of gaussians per nucleon and the gaussian widths are critical parameters in that semi-classical model. (orig.)

  16. Nuclear matter with pseudo-particle model: static bulk and surface properties

    Energy Technology Data Exchange (ETDEWEB)

    Idier, D.; Benhassine, B.; Farine, M.; Remaud, B.; Sebille, F.

    1993-12-31

    Direct calculations of cold and hot nuclear matter (bulk and surface properties) are carried out within the frame of a pseudo-particle model using a Gaussian decomposition of the distribution function. Comparisons with Hartree-Fock calculations, for a large class of effective interactions, show that such a model is reliable to reproduce accurately the equation of state of nuclear matter for large ranges of densities and temperatures. The number of Gaussian per nucleon and the Gaussian widths are critical parameters in that semi-classical model. (author) 13 refs.; 9 figs.; 2 tabs.

  17. Nuclear matter with pseudo-particle model: static bulk and surface properties

    International Nuclear Information System (INIS)

    Idier, D.; Benhassine, B.; Farine, M.; Remaud, B.; Sebille, F.

    1993-01-01

    Direct calculations of cold and hot nuclear matter (bulk and surface properties) are carried out within the frame of a pseudo-particle model using a Gaussian decomposition of the distribution function. Comparisons with Hartree-Fock calculations, for a large class of effective interactions, show that such a model is reliable to reproduce accurately the equation of state of nuclear matter for large ranges of densities and temperatures. The number of Gaussian per nucleon and the Gaussian widths are critical parameters in that semi-classical model. (author) 13 refs.; 9 figs.; 2 tabs

  18. Nuclear matter with a pseudo-particle model: static bulk and surface properties

    Energy Technology Data Exchange (ETDEWEB)

    Idier, D. (Lab. de Physique Nucleaire CNRS/IN2P3, Univ. de Nantes (France)); Benhassine, B. (Lab. de Physique Nucleaire CNRS/IN2P3, Univ. de Nantes (France)); Farine, M. (Lab. de Physique Nucleaire CNRS/IN2P3, Univ. de Nantes (France)); Remaud, B. (Lab. de Physique Nucleaire CNRS/IN2P3, Univ. de Nantes (France)); Sebille, F. (Lab. de Physique Nucleaire CNRS/IN2P3, Univ. de Nantes (France))

    1993-11-15

    Direct calculations of cold and hot nuclear matter (bulk and surface properties) are carried out within the frame of a pseudo-particle model using a gaussian decomposition of the distribution function. Comparisons with Hartree-Fock calculations, for a large class of effective interactions, show that such a model is reliable to reproduce accurately the equation of state of nuclear matter for large ranges of densities and temperatures. The number of gaussians per nucleon and the gaussian widths are critical parameters in that semi-classical model. (orig.)

  19. Study on EM-parameters and EM-wave absorption properties of materials with bio-flaky particles added

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenqiang, E-mail: zwqcau@gmail.com [College of Engineering, China Agricultural University, Beijing 100083 (China); Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang, Deyuan; Xu, Yonggang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); McNaughton, Ryan [Department of Biomedical Engineering, Boston University, Boston 02215 (United States)

    2016-01-01

    Bio-flaky particles, fabricated through deposition of carbonyl iron on the surface of disk shaped diatomite, demonstrated beneficial performance on electromagnetic parameters. This paper will detail the improvements to the electromagnetic parameters and absorbing properties of traditional absorbing material generated by the addition of bio-flaky particles. Composites' electromagnetic parameters were measured using the transmission method. Calculated test results confirmed with bio-flaky particles were added, composites' permittivity increased due to the high permeability of bio-flaky particles. Secondly, the permeability of composites increased as a result of the increased volume content of iron particles. Composites with bio-flaky particles added exhibited superlative absorption properties at 0.5 mm thickness, with a maximum reflection loss of approximately −5.1 dB at 14.4 GHz. - Highlights: • Light weight absorbing composites were fabricated with bio-flaky particles added. • SEM results show bio-flaky particles could help the arrangement of FCIPs. • Composites' RL could be improved with bio-flaky particles added. • The RL peak move to lower frequency with bio-flaky particles added.

  20. Study on EM-parameters and EM-wave absorption properties of materials with bio-flaky particles added

    International Nuclear Information System (INIS)

    Zhang, Wenqiang; Zhang, Deyuan; Xu, Yonggang; McNaughton, Ryan

    2016-01-01

    Bio-flaky particles, fabricated through deposition of carbonyl iron on the surface of disk shaped diatomite, demonstrated beneficial performance on electromagnetic parameters. This paper will detail the improvements to the electromagnetic parameters and absorbing properties of traditional absorbing material generated by the addition of bio-flaky particles. Composites' electromagnetic parameters were measured using the transmission method. Calculated test results confirmed with bio-flaky particles were added, composites' permittivity increased due to the high permeability of bio-flaky particles. Secondly, the permeability of composites increased as a result of the increased volume content of iron particles. Composites with bio-flaky particles added exhibited superlative absorption properties at 0.5 mm thickness, with a maximum reflection loss of approximately −5.1 dB at 14.4 GHz. - Highlights: • Light weight absorbing composites were fabricated with bio-flaky particles added. • SEM results show bio-flaky particles could help the arrangement of FCIPs. • Composites' RL could be improved with bio-flaky particles added. • The RL peak move to lower frequency with bio-flaky particles added.

  1. Microphysical characteristics of squall-line stratiform precipitation and transition zones inferred using an ice particle property-evolving model

    Science.gov (United States)

    Jensen, A. A.; Harrington, J. Y.; Morrison, H.

    2017-12-01

    A quasi-idealized 3D squall line (based on a June 2007 Oklahoma case) is simulated using a novel bulk microphysics scheme called the Ice-Spheroids Habit Model with Aspect-ratio Evolution (ISHMAEL). In ISHMAEL, the evolution of ice particle properties, such as mass, shape, maximum diameter, density, and fall speed, are tracked as these properties evolve from vapor growth, sublimation, riming, and melting. Thus, ice properties evolve from various microphysical processes without needing separate unrimed and rimed ice categories. Simulation results show that ISHMAEL produces both a squall-line transition zone and an enhanced stratiform precipitation region. The ice particle properties produced in this simulation are analyzed and compared to observations to determine the characteristics of ice that lead to the development of these squall-line features. It is shown that rimed particles advected rearward from the convective region produce the enhanced stratiform precipitation region. The development of the transition zone results from hydrometer sorting: the evolution of ice particle properties in the convective region produces specific fall speeds that favor significant ice advecting rearward of the transition zone before reaching the melting level, causing a local minimum in precipitation rate and reflectivity there. Microphysical sensitivity studies, for example turning rime splintering off, that lead to changes in ice particle properties reveal that the fall speed of ice particles largely determines both the location of the enhanced stratiform precipitation region and whether or not a transition zone forms.

  2. The influence of particle size and fluorine content of aluminosilicate glass on the glass ionomer cement properties.

    Science.gov (United States)

    De Caluwé, T; Vercruysse, C W J; Fraeyman, S; Verbeeck, R M H

    2014-09-01

    Glass ionomer cements (GIC) are clinically accepted dental restorative materials mainly due to their direct chemical adhesion to both enamel and dentin and their ability to release fluoride. However, their mechanical properties are inferior compared to those of amalgam and composite. The aim of this study is to investigate if combinations of nano- and macrogranular glass with different compositions in a glass ionomer cement can improve the mechanical and physical properties. Glasses with the composition 4.5 SiO2-3 Al2O3-1.5 P2O5-(5-x) CaO-x CaF2 (x=0 and x=2) were prepared. Of each type of glass, particles with a median size of about 0.73 μm and 6.02 μm were made. The results show that the setting time of GIC decreases when macrogranular glass particles are replaced by nanogranular glass particles, whereas the compressive strength and Young's modulus, measured after 24 h setting, increase. The effects are more pronounced when the nanogranular glass particles contain fluoride. After thermocycling, compressive strength decreases for nearly all formulations, the effect being most pronounced for cements containing nanogranular glass particles. Hence, the strength of the GIC seems mainly determined by the macrogranular glass particles. Cumulative F--release decreases when the macrogranular glass particles with fluoride are replaced by nanogranular glass particles with(out) fluoride. The present study thus shows that replacing macro- by nanogranular glass particles with different compositions can lead to cements with approximately the same physical properties (e.g. setting time, consistency), but with different physicochemical (e.g. F--release, water-uptake) and initial mechanical properties. On the long term, the mechanical properties are mainly determined by the macrogranular glass particles. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. The effect of particle aspect ratio on the electroelastic properties of piezoelectric nanocomposites

    International Nuclear Information System (INIS)

    Andrews, C; Lin, Y; Sodano, H A

    2010-01-01

    Piezoelectric materials offer exceptional sensing and actuation properties; however, they are prone to breakage and difficult to apply on curved surfaces in their monolithic form. One method of alleviating these issues is through the use of 0–3 nanocomposites, which are formed by embedding piezoelectric particles into a polymer matrix. Material of this class offers certain advantages over monolithic materials; however, it has seen little use due to its low coupling. Here we develop micromechanics and finite element models to study the electroelastic properties of an active nanocomposite, as a function of the aspect ratio and alignment of the piezoelectric filler. Our results show that the aspect ratio is critical for achieving high electromechanical coupling, and with an increase from 1 to 10 at 30% volume fraction of piezoelectric filler the coupling can increase to 60 times its initial value and achieve a bulk composite coupling as high as 90% for a pure PZT-7A piezoelectric constituent

  4. Molecular and structural properties of polymer composites filled with activated charcoal particles

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, Dahlang, E-mail: dtahir@fmipa.unhas.ac.id; Bakri, Fahrul [Department of Physics, Hasanuddin University, Makassar 90245 Indonesia (Indonesia); Liong, Syarifuddin [Department of Chemistry, Hasanuddin University, Makassar 90245 Indonesia (Indonesia)

    2016-03-11

    We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH{sub 3}) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO{sub 3}, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is about 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.

  5. Dynamical properties for an ensemble of classical particles moving in a driven potential well with different time perturbation

    International Nuclear Information System (INIS)

    Costa, Diogo Ricardo da; Caldas, I.L.; Leonel, Edson D.

    2013-01-01

    We consider dynamical properties for an ensemble of classical particles confined to an infinite box of potential and containing a time-dependent potential well described by different nonlinear functions. For smooth functions, the phase space contains chaotic trajectories, periodic islands and invariant spanning curves preventing the unlimited particle diffusion along the energy axis. Average properties of the chaotic sea are characterised as a function of the control parameters and exponents describing their behaviour show no dependence on the perturbation functions. Given invariant spanning curves are present in the phase space, a sticky region was observed and show to modify locally the diffusion of the particles

  6. Mechanical properties study of particles reinforced aluminum matrix composites by micro-indentation experiments

    Directory of Open Access Journals (Sweden)

    Yuan Zhanwei

    2014-04-01

    Full Text Available By using instrumental micro-indentation technique, the microhardness and Young’s modulus of SiC particles reinforced aluminum matrix composites were investigated with micro-compression-tester (MCT. The micro-indentation experiments were performed with different maximum loads, and with three loading speeds of 2.231, 4.462 and 19.368 mN/s respectively. During the investigation, matrix, particle and interface were tested by micro-indentation experiments. The results exhibit that the variations of Young’s modulus and microhardness at particle, matrix and interface were highly dependent on the loading conditions (maximum load and loading speed and the locations of indentation. Micro-indentation hardness experiments of matrix show the indentation size effects, i.e. the indentation hardness decreased with the indentation depth increasing. During the analysis, the effect of loading conditions on Young’s modulus and microhardness were explained. Besides, the elastic–plastic properties of matrix were analyzed. The validity of calculated results was identified by finite element simulation. And the simulation results had been preliminarily analyzed from statistical aspect.

  7. Aging behavior and mechanical properties of maraging steels in the presence of submicrocrystalline Laves phase particles

    International Nuclear Information System (INIS)

    Mahmoudi, A.; Ghavidel, M.R. Zamanzad; Nedjad, S. Hossein; Heidarzadeh, A.; Ahmadabadi, M. Nili

    2011-01-01

    Cold rolling and annealing of homogenized Fe-Ni-Mn-Mo-Ti-Cr maraging steels resulted in the formation of submicrocrystalline Fe 2 (Mo,Ti) Laves phase particles. Optical and scanning electron microscopy, X-ray diffraction, tensile and hardness tests were used to study the microstructure, aging behavior and mechanical properties of the annealed steels. The annealed microstructures showed age hardenability during subsequent isothermal aging at 753 K. Ultrahigh fracture stress but poor tensile ductility was obtained after substantial age hardening in the specimens with 2% and 4% chromium. Increasing chromium addition up to 6% toughened the aged microstructure at the expense of the fracture stress by increasing the volume fraction of retained austenite. The Laves phase particles acted as crack nucleation sites during tensile deformation. - Highlights: → Laves phases dispersed in a BCC iron matrix by annealing of cold rolled samples. → The samples showed age hardenability during subsequent isothermal aging at 753 K. → Ultrahigh fracture stress but poor ductility was obtained after age hardening. → Increasing chromium addition toughened the aged microstructure. → Laves phase particles acting as crack nucleation sites during tensile deformation.

  8. Particle morphology of hydroxyapatite and its influence on the properties of biocomposite plasma coatings

    Directory of Open Access Journals (Sweden)

    Melnikova I.P.

    2013-09-01

    Full Text Available The purpose of the article is to identify patterns of change in the properties of biocompatible coatings during modernization of its structure by changing the morphology and crystallinity of the starting powder particles of hydroxyapatite (HA for agglomeration and subsequent grinding. Material and methods. We investigated the morphology, degree of crystallinity and internal tension in HA powder with a particle size of 40-90 microns in the initial state and after the agglomeration process and structure piasmasprayed HA coatings application methods ray analysis (XRF and XRD on DRON-3, infrared spectroscopy (FT-IR spectrometer Nicolet 6700, optical (MIM-8 and atomic force microscopy (SMM-2000, the laser microprobe (Spectrum 2000. Results: It was shown that change in particle morphology HA agglomerated and subsequently grinding increases the uniformity of the porous structure, its crystallinity, reduce internal stresses developing surface morphology of the coating and its nanostructuring. Conclusion. It is recommended for the improvement of characteristics of the porous structure (uniformity, strength, adhesion, and the surface morphology of implant to use agglomerating starting powders and their subsequent grinding.

  9. Surface modification of silica particles and its effects on cure and mechanical properties of the natural rubber composites

    Energy Technology Data Exchange (ETDEWEB)

    Theppradit, Thawinan [Program in Petrochemistry and Polymer Science, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Prasassarakich, Pattarapan [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Poompradub, Sirilux, E-mail: sirilux.p@chula.ac.th [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

    2014-12-15

    The efficiency of modified silica (SiO{sub 2}) particles in the reinforcement of natural rubber (NR) vulcanizates was evaluated. The SiO{sub 2} particles were synthesized via a sol–gel reaction using tetraethyl orthosilicate as the precursor, and then the formed SiO{sub 2} particles were modified with methyl, vinyl or aminopropyl groups using methyltriethoxysilane, vinyltriethoxysilane or aminopropyltrimethoxysilane, respectively. Fourier transform infrared spectroscopy and elemental analysis confirmed the successful modification of the surface of the silica particles. The water contact angle measurement revealed the greater hydrophobicity of the three modified silica preparations compared to the unmodified SiO{sub 2}. NR vulcanizates filled with modified SiO{sub 2} particles were prepared and the mechanical, thermal and dynamic mechanical properties of composites were investigated. The morphology of composite materials was also investigated by scanning electron microscopy. The modified SiO{sub 2} particles were well dispersed in the NR matrix leading to the good compatibility between the rubber and filler, and so an improved cure, mechanical, thermal and dynamic mechanical properties of the composite vulcanizate materials. - Highlights: • Modification of SiO{sub 2} particles by MTES, VTES and APTES. • Improvement of hydrophobicity of SiO{sub 2} particle and compatibility between SiO{sub 2} and rubbery matrix. • Improvement of cure, mechanical, thermal, dynamic mechanical properties of NR vulcanizates.

  10. Effect of particle size and concentration on the mechanical properties of polyester/date palm seed particulate composites

    Directory of Open Access Journals (Sweden)

    Alewo Opuada AMEH

    2015-05-01

    Full Text Available The use of cellulosic materials as reinforcement in composites can greatly enhance their properties. The thrust of this study was to investigate the effect of date palm seed particle on the properties of reinforced polyester. Unsaturated polyester resin was reinforced with date palm seed particles of 0.5, 2.0 and 2.8mm particle sizes using variable particle loadings of 5, 10, 15, 20 and 25wt%. The composites obtained were subjected to various types of mechanical and physical tests in order to assess their performance. The optimum tensile strength of 16.7619N/mm2 and elastic modulus of 343.8N/mm2 were attained at 15wt% and 10wt% loading (using 0.5mm particles respectively and percent water absorption was found to be least for 0.5mm particle size. The hardness was enhanced to the maximum of 74 HRF (Rockwell Hardness Factor by 2mm particle size at 25wt% loading. Pure unsaturated polyester resin recorded tensile strength of 17.5959N/mm2, elastic modulus of 316.7N/mm2 and hardness of 33.5 HRF. The results indicated that the use of date palm seed particles as reinforcement can enhance the properties of polyester composites.

  11. Corrosion and magnetic properties of encapsulated carbonyl iron particles in aqueous suspension by inorganic thin films for magnetorheological finishing application

    Science.gov (United States)

    Esmaeilzare, Amir; Rezaei, Seyed Mehdi; Ramezanzadeh, Bahram

    2018-04-01

    Magnetorheological fluid is composed of micro-size carbonyl iron (CI) particles for polishing of optical substrates. In this paper, the corrosion resistance of carbonyl iron (CI) particles modified with three inorganic thin films based on rare earth elements, including cerium oxide (CeO2), lanthanum oxide (La2O3) and praseodymium oxide (Pr2O3), was investigated. The morphology and chemistry of the CI-Ce, CI-Pr and CI-La particles were examined by high resolution Field Emission-Scanning Electron Microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests were carried out to investigate the corrosion behavior of CI particles in aquatic environment. In addition, the Vibrating Sample Magnetometer (VSM) technique was utilized for determination of magnetic saturation properties of the coated particles. Afterwards, gas pycnometry and contact angle measurement methods were implemented to evaluate the density and hydrophilic properties of these particles. The results showed that deposition of all thin films increased the hydrophilic nature of these particles. In addition, it was observed that the amount of magnetic saturation properties attenuation for Pr2O3 and La2O3 films is greater than the CeO2 film. The EIS and polarization tests results confirmed that the CI-Ce had the maximum corrosion resistant among other samples. In addition, the thermogravimetric analysis (TGA) showed that the ceria coating provided particles with enhanced surface oxidation resistance.

  12. Assembly and luminescence properties of lanthanide-polyoxometalates/polyethyleneimine/SiO{sub 2} particles with core–shell structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun, E-mail: junwang924@yahoo.com.cn; Fan, Shaohua; Zhao, Weiqian; Zhang, Hongyan

    2013-01-01

    In this paper, two lanthanide-polyoxometalate (LnW{sub 10}) complexes were bonded on the surface of the polyethyleneimine (PEI)-modified silica nanoparticles with different sizes, resulting in the formation of LnW{sub 10}/PEI/SiO{sub 2} particles. The hybrid core–shell particles were characterized by infrared, luminescent spectra, scanning electronic microscope, and transmission electronic microscope. The particles obtained exhibit the fine spherical core–shell structure and the excellent luminescence properties. The luminescence spectra studies revealed that the formation of LnW{sub 10}/PEI/SiO{sub 2} particles and the size of particle have an influence on the luminescence properties of lanthanide ions. - Highlights: ► SiO{sub 2}/polyethyleneimine (PEI) shows the chemisorption for Ln-polyoxometalates (LnW{sub 10}). ► The core-shell LnW{sub 10}/PEI/SiO{sub 2} nanoparticles with different sizes were fabricated. ► The hybrid particles exhibit the excellent luminescence properties. ► The sizes of particles affect the luminescence properties of lanthanide ions.

  13. Evolution of Single Particle and Collective properties in the Neutron-Rich Mg Isotopes

    CERN Multimedia

    Reiter, P; Wiens, A; Fitting, J; Lauer, M; Van duppen, P L E; Finke, F

    2002-01-01

    We propose to study the single particle and collective properties of the neutron-rich Mg isotopes in transfer reactions and Coulomb excitation using REX-ISOLDE and MINIBALL. From the Coulomb excitation measurement precise and largely model independent B( E2 ; 0$^{+}_{g.s.}\\rightarrow$ 2$^{+}_{1}$ ) will be determined for the even-even isotopes. For the odd isotopes the distribution of the E2 strength over a few low-lying states will be measured. The sign of the M1/E2 mixing ratio, extracted from angular distributions, is characteristic of the sign of the deformation, as is the resulting level scheme. The neutron-pickup channel in the transfer reactions will allow for a determination of the single particle properties (spin, parity, spectroscopic factors) of these nuclei. This information will give new insights in changes of nuclear structure in the vicinity of the island of deformation around $^{32}$Mg. A total of 24 shifts of REX beam time is requested.

  14. Enhanced antioxidation and microwave absorbing properties of SiO2-coated flaky carbonyl iron particles

    Science.gov (United States)

    Zhou, Yingying; Xie, Hui; Zhou, Wancheng; Ren, Zhaowen

    2018-01-01

    SiO2 was successfully coated on the surface of flaky carbonyl iron particles using a chemical bath deposition method in the presence of 3-aminopropyl triethoxysilane (APTES). The morphologies, composition, valence states of elements, as well as antioxidation and electromagnetic properties of the samples were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) and microwave network analyzer. TG curve shows the obvious weight gain of carbonyl iron was deferred to 360 °C after SiO2-coated, which can be ascribed to the exits of SiO2 overlayer. Compared with the raw carbonyl iron, SiO2-coated sample shows good wave absorption performance due to its impedance matching. The electromagnetic properties of raw and SiO2-coated carbonyl iron particles were characterized in X band before and after heat treatment at 250 °C for 10 h. It was established that SiO2-coated carbonyl iron demonstrate good thermal stability, indicating SiO2-coating is useful in the usage of microwave absorbers operating at temperature up to 250 °C.

  15. Synthesis, Characterization, and Magnetic Properties of Pure and EDTA-Capped NiO Nanosized Particles

    Directory of Open Access Journals (Sweden)

    H. T. Rahal

    2017-01-01

    Full Text Available The effect of ethylenediaminetetraacetic acid (EDTA as a capping agent on the structure, morphology, optical, and magnetic properties of nickel oxide (NiO nanosized particles, synthesized by coprecipitation method, was investigated. Nickel chloride hexahydrate and sodium hydroxide (NaOH were used as precursors. The resultant nanoparticles were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and scanning electron microscopy (SEM. XRD patterns showed that NiO have a face-centered cubic (FCC structure. The crystallite size, estimated by Scherrer formula, has been found in the range of 28–33 nm. It is noticed that EDTA-capped NiO nanoparticles have a smaller size than pure nanoparticles. Thus, the addition of 0.1 M capping agent EDTA can form a nucleation point for nanoparticles growth. The optical and magnetic properties were investigated by Fourier transform infrared spectroscopy (FTIR and UV-vis absorption spectroscopy (UV as well as electron paramagnetic resonance (EPR and magnetization measurements. FTIR spectra indicated the presence of absorption bands in the range of 402–425 cm−1, which is a common feature of NiO. EPR for NiO nanosized particles was measured at room temperature. An EPR line with g factor ≈1.9–2 is detected for NiO nanoparticles, corresponding to Ni2+ ions. The magnetic hysteresis of NiO nanoparticles showed that EDTA capping recovers the surface magnetization of the nanoparticles.

  16. The magnetic field dependent dynamic properties of magnetorheological elastomers based on hard magnetic particles

    Science.gov (United States)

    Wen, Qianqian; Wang, Yu; Gong, Xinglong

    2017-07-01

    In this study, novel magnetorheological elastomers based on hard magnetic particles (H-MREs) were developed and the magnetic field dependent dynamic properties of the H-MREs were further investigated. The storage modulus of H-MREs could not only be increased by increasing magnetic field but also be decreased by the increasing magnetic field of opposite orientation. For the anisotropic H-MREs with 80 wt% NdFeB particles, the field-induced increasing and decreasing modulus was 426 kPa and 118 kPa respectively. Moreover, the dynamic performances of H-MREs significantly depended on the pre-structure magnetic field, magnetizing field and test magnetic field. The H-MREs were initially magnetized and formed the chain-like microstructure by the pre-structure magnetic field. The field-induced increasing and decreasing modulus of H-MREs both raised with increasing of the magnetizing field. When the magnetizing field increased from 400 to 1200 kA m-1, the field induced decreasing modulus of the 80 wt% isotropic H-MREs raised from 3 to 47 kPa. The magnetic field dependent curves of H-MREs’ storage modulus were asymmetric if the magnetizing field was higher than the test magnetic field. Based on the dipolar model of MREs and magnetic properties of hard magnetic material, a reasonable explanation was proposed to understand the H-MREs’ field dependent mechanical behaviors.

  17. Fractal scaling of particle size distribution and relationships with topsoil properties affected by biological soil crusts.

    Directory of Open Access Journals (Sweden)

    Guang-Lei Gao

    Full Text Available BACKGROUND: Biological soil crusts are common components of desert ecosystem; they cover ground surface and interact with topsoil that contribute to desertification control and degraded land restoration in arid and semiarid regions. METHODOLOGY/PRINCIPAL FINDINGS: To distinguish the changes in topsoil affected by biological soil crusts, we compared topsoil properties across three types of successional biological soil crusts (algae, lichens, and mosses crust, as well as the referenced sandland in the Mu Us Desert, Northern China. Relationships between fractal dimensions of soil particle size distribution and selected soil properties were discussed as well. The results indicated that biological soil crusts had significant positive effects on soil physical structure (P<0.05; and soil organic carbon and nutrients showed an upward trend across the successional stages of biological soil crusts. Fractal dimensions ranged from 2.1477 to 2.3032, and significantly linear correlated with selected soil properties (R(2 = 0.494∼0.955, P<0.01. CONCLUSIONS/SIGNIFICANCE: Biological soil crusts cause an important increase in soil fertility, and are beneficial to sand fixation, although the process is rather slow. Fractal dimension proves to be a sensitive and useful index for quantifying changes in soil properties that additionally implies desertification. This study will be essential to provide a firm basis for future policy-making on optimal solutions regarding desertification control and assessment, as well as degraded ecosystem restoration in arid and semiarid regions.

  18. Properties and effects of dust particles suspended in the martian atmosphere

    International Nuclear Information System (INIS)

    Pollack, J.B.; Colburn, D.S.; Flasar, M.; Kahn, R.; Carlston, C.E.; Pidek, D.

    1979-01-01

    Direct measurements of the optical depth above the two Viking landers are reported for a period of covering the summer, fall, and winter seasons in the northern hemisphere, a time period during which two global dust storms occurred. The optical depth had a value of about 1 just before the onset of each storm; it increased very rapidly, on a time scale of a few days, to peak values of about 3 and 6 with the arrival of the first and second storms, respectively; and its steadily decreased shortly thereafter (> or approx. = few days to few weeks) for both storms, with the decay occurring more rapidly during the initial period of decay. We have also carried out further analyses of observations of the sky brightness made with the lander cameras during the summer season to obtain improved estimates of other dust particle parameters, including the cross section weighted mean particle radius, several shape factors, and the imaginary indices of refraction. These results have been used to define the radiative properties of the suspended dust particles at solar wavelenths. The derived radiative properties of the dust were incorporated into a 1D radiative convective model. Satisfactory agreement with the temperature structure determined during the descent of the landers to the surface. Is achieved when allowance is made for the effects of vertical motions induced by large scale atmospheric dynamics. The diurnal temperature variations predicted by the 1D calculations for the observed optical depths are also in crude agreement with values inferred from orbiter and lander measurements. The 1D model predicts that the diurnal temperature change and daily mean temperature, averaged over the entire atmospheric vertical column, steadily increase as the optical depth of the dust increases to a value of several, and then subsequently change little

  19. Global particle balance and wall recycling properties of long duration discharges on TRIAM-1M

    International Nuclear Information System (INIS)

    Sakamoto, M.; Yuno, M.; Itoh, S.

    2003-01-01

    The longest tokamak discharge with the duration of 11406 s (3 h 10 min) was achieved. The global particle balance has been investigated. In the longest discharge, the global balance between the particle absorption and release of the wall was achieved around t∼30 min and then the fueling was automatically stopped. After that the plasma density was maintained by the recycling flux alone until the end of the discharge. The maximum wall inventory is about 3.6 x 10 20 H at t ∼ 30 min but it is finally released from the wall at the end of the discharge. The global balance seems to be caused by the increase in the hydrogen release from the main chamber resulting from its temperature rise. Moreover, it has been observed a large difference between properties of wall recycling in the continuous gas feed case (i.e. static condition) and the additional gas puff case (i.e. dynamic condition). In the static condition, the effective particle confinement time increases almost linearly to about 10 s during the one-minute discharge. In the dynamic condition, the decay time of the electron density just after the gas puff, i.e. the effective particle confinement time, is 0.2 to 0.3 s during the one-minute discharge. The large difference was also reproduced in the longest discharge. It is considered that the enhanced wall pumping is caused by the increase in fluxes of the diffused ions and charge exchange neutrals due to the additional gas puff. (author)

  20. Ice Nucleating Particle Properties in the Saharan Air Layer Close to the Dust Source

    Science.gov (United States)

    Boose, Y.; Garcia, I. M.; Rodríguez, S.; Linke, C.; Schnaiter, M.; Nickovic, S.; Lohmann, U.; Kanji, Z. A.; Sierau, B.

    2015-12-01

    In August 2013 and 2014 measurements of ice nucleating particle (INP) concentrations, aerosol particle size distributions, chemistry and fluorescence were conducted at the Izaña Atmospheric Observatory located at 2373 m asl on Tenerife, west off the African shore. During summer, the observatory is frequently within the Saharan Air Layer and thus often exposed to dust. Absolute INP concentrations and activated fractions at T=-40 to -15°C and RHi=100-150 % were measured. In this study, we discuss the in-situ measured INP properties with respect to changes in the chemical composition, the biological content, the source regions as well as transport pathways and thus aging processes of the dust aerosol. For the first time, ice crystal residues were also analyzed with regard to biological content by means of their autofluorescence signal close to a major dust source region. Airborne dust samples were collected with a cyclone for additional offline analysis in the laboratory under similar conditions as in the field. Both, in-situ and offline dust samples were chemically characterized using single-particle mass spectrometry. The DREAM8 dust model extended with dust mineral fractions was run to simulate meteorological and dust aerosol conditions for ice nucleation. Results show that the background aerosol at Izaña was dominated by carbonaceous particles, which were hardly ice-active under the investigated conditions. When Saharan dust was present, INP concentrations increased by up to two orders of magnitude even at water subsaturated conditions at T≤-25°C. Differences in the ice-activated fraction were found between different dust periods which seem to be linked to variations in the aerosol chemical composition (dust mixed with changing fractions of sea salt and differences in the dust aerosol itself). Furthermore, two biomass burning events in 2014 were identified which led to very low INP concentrations under the investigated temperature and relative humidity

  1. Effect of aluminium particles on mechanical and morphological properties of epoxy nanocomposites

    Directory of Open Access Journals (Sweden)

    Bello Sefiu A.

    2017-01-01

    Full Text Available Bumper is a front or rear part of automobiles. It is designed and shaped to be impact absorbing and protecting automobiles from damage in low impact collisions. Initially, they were made from heavy steels, increasing the weight of automobiles and fuel consumption. Also, high impacts of steel bumpers on pedestrians during accidental collision cause fatalities and or disabilities. An effort to enhance fuel efficiency, safety, freedom of design and shape detailing, heavy alloys for automobile applications are now being replaced with polymeric composites. Aluminium micro particles and nanoparticles were prepared from aluminium cans through sand casting, lathe machine spinning, and ball milling techniques. Both types of aluminium particles were incorporated into a mixture of diglycidyl ether of bisphenol A (DGEBA, epoxy resin cured with amine base hardener (ABH. Phases of the epoxy polymer and composites were identified using Xray Diffraction (XRD. Spatial arrangement of the phases within the matrix and their elemental composition were examined using Scanning Electron Microscope with attached energy dispersive X-ray spectroscopy (SEM/EDX. Tensile, impact and micro hardness tests were conducted on the prepared epoxy/aluminium composites. Results of the XRD showed the presence of aluminium compounds/phases due to chemical reactions between aluminium particles and DGEBA/ABH system. SEM confirmed a homogeneous distribution of the phases within the epoxy matrix, and that there is a strong adhesion between the epoxy matrix and aluminium particles. Correlation between the mechanical properties of the prepared nanocomposite and the procured bumper materials exhibited a fair suitability of the prepared nanocomposites for automobile applications.

  2. Structural properties of silver nanoparticle agglomerates based on transmission electron microscopy: relationship to particle mobility analysis

    International Nuclear Information System (INIS)

    Shin, Weon Gyu; Wang Jing; Mertler, Michael; Sachweh, Bernd; Fissan, Heinz; Pui, David Y. H.

    2009-01-01

    In this work, the structural properties of silver nanoparticle agglomerates generated using condensation and evaporation method in an electric tube furnace followed by a coagulation process are analyzed using Transmission Electron Microscopy (TEM). Agglomerates with mobility diameters of 80, 120, and 150 nm are sampled using the electrostatic method and then imaged by TEM. The primary particle diameter of silver agglomerates was 13.8 nm with a standard deviation of 2.5 nm. We obtained the relationship between the projected area equivalent diameter (d pa ) and the mobility diameter (d m ), i.e., d pa = 0.92 ± 0.03 d m for particles from 80 to 150 nm. We obtained fractal dimensions of silver agglomerates using three different methods: (1) D f = 1.84 ± 0.03, 1.75 ± 0.06, and 1.74 ± 0.03 for d m = 80, 120, and 150 nm, respectively from projected TEM images using a box counting algorithm; (2) fractal dimension (D fL ) = 1.47 based on maximum projected length from projected TEM images using an empirical equation proposed by Koylu et al. (1995) Combust Flame 100:621-633; and (3) mass fractal-like dimension (D fm ) = 1.71 theoretically derived from the mobility analysis proposed by Lall and Friedlander (2006) J Aerosol Sci 37:260-271. We also compared the number of primary particles in agglomerate and found that the number of primary particles obtained from the projected surface area using an empirical equation proposed by Koylu et al. (1995) Combust Flame 100:621-633 is larger than that from using the relationship, d pa = 0.92 ± 0.03 d m or from using the mobility analysis.

  3. Multiscale structure, interfacial cohesion, adsorbed layers, miscibility and properties in dense polymer-particle mixtures

    Science.gov (United States)

    Schweizer, Ken

    2012-02-01

    A major goal in polymer nanocomposite research is to understand and predict how the chemical and physical nature of individual polymers and nanoparticles, and thermodynamic state (temperature, composition, solvent dilution, filler loading), determine bulk assembly, miscibility and properties. Microscopic PRISM theory provides a route to this goal for equilibrium disordered mixtures. A major prediction is that by manipulating the net polymer-particle interfacial attraction, miscibility is realizable via the formation of thin thermodynamically stable adsorbed layers, which, however, are destroyed by entropic depletion and bridging attraction effects if interface cohesion is too weak or strong, respectively. This and related issues are quantitatively explored for miscible mixtures of hydrocarbon polymers, silica nanospheres, and solvent using x-ray scattering, neutron scattering and rheology. Under melt conditions, quantitative agreement between theory and silica scattering experiments is achieved under both steric stabilization and weak depletion conditions. Using contrast matching neutron scattering to characterize the collective structure factors of polymers, particles and their interface, the existence and size of adsorbed polymer layers, and their consequences on microstructure, is determined. Failure of the incompressible RPA, accuracy of PRISM theory, the nm thickness of adsorbed layers, and qualitative sensitivity of the bulk modulus to interfacial cohesion and particle size are demonstrated for concentrated PEO-silica-ethanol nanocomposites. Temperature-dependent complexity is discovered when water is the solvent, and nonequilibrium effects emerge for adsorbing entangled polymers that strongly impact structure. By varying polymer chemistry, the effect of polymer-particle attraction on the intrinsic viscosity is explored with striking non-classical effects observed. This work was performed in collaboration with S.Y.Kim, L.M.Hall, C.Zukoski and B.Anderson.

  4. The Effects of Particle Size on the Surface Properties of an HVOF Coating of WC-Co

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Tong Yul; Yoon, Jae Hong; Yoon, Sang Hwan; Joo, Yun Kon [Changwon National University, Changwon (Korea, Republic of); Choi, Won Ho; Son, Young Bok [Xinix Metallizing Co., Ltd, Gyungnam (Korea, Republic of)

    2017-04-15

    The effects of particle size on the surface properties of HVOF spray coating were studied to improve of the durability of metal components. Micro and nano sized WC-12Co powders were coated on the surface of Inconel718, and the effects of particle size on surface properties were studied. Surface hardness was reduced when the particle sizes of the powder were decreased, because the larger specific surface area of the smaller particles caused greater heat absorption and decomposition of the hard WC to less hard W{sub 2}C and graphite. Porosity was increased by decreasing the particle size, because the larger specific surface area of the smaller particles caused a greater decomposition of WC to W{sub 2}C and free carbon. The free carbon formed carbon oxide gases which created the porous surface. The friction coefficient was reduced by decreasing the particle size because the larger specific surface area of the smaller particles produced more free carbon free Co and Co oxide which acted as solid lubricants. The friction coefficient increased when the surface temperature was increased from 25 to 500 ℃, due to local cold welding. To improve the durability of metal mechanical components, WC-Co coating with the proper particle size is recommended.

  5. Physical properties and structure of fine core-shell particles used as packing materials for chromatography Relationships between particle characteristics and column performance.

    Science.gov (United States)

    Gritti, Fabrice; Leonardis, Irene; Abia, Jude; Guiochon, Georges

    2010-06-11

    The recent development of new brands of packing materials made of fine porous-shell particles, e.g., Halo and Kinetex, has brought great improvements in potential column efficiency, demanding considerable progress in the design of chromatographic instruments. Columns packed with Halo and Kinetex particles provide minimum values of their reduced plate heights of nearly 1.5 and 1.2, respectively. These packing materials have physical properties that set them apart from conventional porous particles. The kinetic performance of 4.6mm I.D. columns packed with these two new materials is analyzed based on the results of a series of nine independent and complementary experiments: low-temperature nitrogen adsorption (LTNA), scanning electron microscopy (SEM), inverse size-exclusion chromatography (ISEC), Coulter counter particle size distributions, pycnometry, height equivalent to a theoretical plate (HETP), peak parking method (PP), total pore blocking method (TPB), and local electrochemical detection across the column exit section (LED). The results of this work establish links between the physical properties of these superficially porous particles and the excellent kinetic performance of columns packed with them. It clarifies the fundamental origin of the difference in the chromatographic performances of the Halo and the Kinetex columns. Copyright 2010 Elsevier B.V. All rights reserved.

  6. Preparation, microstructure and magnetic properties of Sm(Co,Hf){sub 7}/Co nanocomposite particles by polyol method

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Shao-Jing; Duan, Xiu-Li; Han, Xu-Hao; Sun, Ji-Bing, E-mail: hbgdsjb@126.com; Chi, Xiang; Cui, Chun-Xiang

    2017-02-01

    Hard/soft Sm-Co/Co nanocomposite particles were prepared by reducing CoCl{sub 2}·6H{sub 2}O in the solution containing ball-milled Sm(Co, Hf){sub 7} particles by a simple polyol method with ethylene glycol as the solvent. Phase composition, microstructure and magnetic properties of the particles were analyzed by XRD, TEM (HRTEM) and VSM, respectively. It has been found that Sm-Co/Co core/shell structure is formed in which the Co shell is 3–5 nm in thickness and mainly exists in hcp-Co phase. At the same time, fcc-Co tends to nucleate and grow independently between Sm-Co particles. The formation mechanism of Sm-Co/Co composite particles is discussed and corresponding model is established. Sm-Co/Co composite particles perform obvious remanence enhancement effects especially after being heated at 450 °C for 15 min.

  7. The effect of SiC particle size on the properties of Cu–SiC composites

    International Nuclear Information System (INIS)

    Celebi Efe, G.; Zeytin, S.; Bindal, C.

    2012-01-01

    Graphical abstract: The relative densities of Cu–SiC composites sintered at 700 °C for 2 h are ranged from 97.3% to 91.8% for SiC with 1 μm particle size and 97.5% to 95.2% for SiC with 5 μm particle size, microhardness of composites ranged from 143 to 167 HV for SiC having 1 μm particle size and 156–182 HVN for SiC having 5 μm particle size and the electrical conductivity of composites changed between 85.9% IACS and 55.7% IACS for SiC with 1 μm particle size, 87.9% IACS and 65.2%IACS for SiC with 5 μm particle size. It was found that electrical conductivity of composites containing SiC with 5 μm particle size is better than that of Cu–SiC composites containing SiC with particle size of 1 μm. Highlights: ► In this research, the effect of SiC particle size on some properties of Cu–SiC composites were investigated. ► The mechanical properties were improved. ► The electrical properties were obtained at desirable level. -- Abstract: SiC particulate-reinforced copper composites were prepared by powder metallurgy (PM) method and conventional atmospheric sintering. Scanning electron microscope (SEM), X-ray diffraction (XRD) techniques were used to characterize the sintered composites. The effect of SiC content and particle size on the relative density, hardness and electrical conductivity of composites were investigated. The relative densities of Cu–SiC composites sintered at 700 °C for 2 h are ranged from 97.3% to 91.8% for SiC with 1 μm particle size and from 97.5% to 95.2% for SiC with 5 μm particle size. Microhardness of composites ranged from 143 to 167 HV for SiC having 1 μm particle size and from 156 to 182 HV for SiC having 5 μm particle size. The electrical conductivity of composites changed between 85.9% IACS and 55.7% IACS for SiC with 1 μm particle size, between 87.9% IACS and 65.2% IACS for SiC with 5 μm particle size.

  8. Effect of Particle Size on Mechanical Properties of Sawdust-High Density Polyethylene Composites under Various Strain Rates

    Directory of Open Access Journals (Sweden)

    Haliza Jaya

    2016-06-01

    Full Text Available There is a need to understand the effect of wood particle size, as it affects the characteristics of wood-based composites. This study considers the effect of wood particle size relative to the dynamic behavior of wood composites. The compression Split Hopkinson Pressure Bar (SHPB was introduced to execute dynamic compression testing at the strain rate of 650 s-1, 900 s-1, and 1100 s-1, whereas a conventional universal testing machine (UTM was used to perform static compression testing at the strain rate of 0.1 s-1, 0.01 s-1, and 0.001 s-1 for four different particle sizes (63 µm, 125 µm, 250 µm, and 500 µm. The results showed that mechanical properties of composites were positively affected by the particle sizes, where the smallest particle size gave the highest values compared to the others. Moreover, the particle size also affected the rate sensitivity and the thermal activation volume of sawdust/HDPE, where smaller particles resulted in lower rate sensitivity. For the post-damage analysis, the applied strain rates influenced deformation behavior differently for all particle sizes of the specimens. In a fractographic analysis under dynamic loading, the composites with large particles experienced severe catastrophic deformation and damages compared to the smaller particles.

  9. Hygroscopic properties of internally mixed particles composed of NaCl and water-soluble organic acids.

    Science.gov (United States)

    Ghorai, Suman; Wang, Bingbing; Tivanski, Alexei; Laskin, Alexander

    2014-02-18

    Atmospheric aging of naturally emitted marine aerosol often leads to formation of internally mixed particles composed of sea salts and water-soluble organic compounds of anthropogenic origin. Mixing of sea salt and organic components has profound effects on the evolving chemical composition and hygroscopic properties of the resulted particles, which are poorly understood. Here, we have studied chemical composition and hygroscopic properties of laboratory generated NaCl particles mixed with malonic acid (MA) and glutaric acid (GA) at different molar ratios using micro-FTIR spectroscopy, atomic force microscopy, and X-ray elemental microanalysis. Hygroscopic properties of internally mixed NaCl and organic acid particles were distinctly different from pure components and varied significantly with the type and amount of organic compound present. Experimental results were in a good agreement with the AIM modeling calculations of gas/liquid/solid partitioning in studied systems. X-ray elemental microanalysis of particles showed that Cl/Na ratio decreased with increasing organic acid component in the particles with MA yielding lower ratios relative to GA. We attribute the depletion of chloride to the formation of sodium malonate and sodium glutarate salts resulted by HCl evaporation from dehydrating particles.

  10. Preparation and magnetic properties of nano size nickel ferrite particles using hydrothermal method

    Directory of Open Access Journals (Sweden)

    Nejati Kamellia

    2012-03-01

    Full Text Available Abstract Background Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate on the particles growth is investigated. Methods For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FT-IR, vibrating sample magnetometer (VSM and inductively coupled plasma atomic emission spectrometer (ICP-AES techniques were used to characterize the samples. Results The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature. Conclusions Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of

  11. Production of bone cement composites: effect of fillers, co-monomer and particles properties

    Energy Technology Data Exchange (ETDEWEB)

    Santos Junior, J.G.F.; Melo, P.A.; Pinto, J.C., E-mail: jjunior@peq.coppe.ufrj.b, E-mail: melo@peq.coppe.ufrj.b, E-mail: pinto@peq.coppe.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia. (PEQ/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Quimica; Pita, V.J.R.R., E-mail: vjpita@ima.ufrj.b [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Eloisa Mano; Nele, M. [Universidade Federal do Rio de Janeiro (EQ/UFRJ), RJ (Brazil). Escola de Quimica

    2011-04-15

    Artificial bone cements (BCs) based on poly(methyl methacrylate) (PMMA) powders and methyl methacrylate (MMA) liquid monomer also present in their formulation small amounts of other substances, including a chemical initiator compound and radiopaque agents. Because inadequate mixing of the recipe components during the manufacture of the bone cement may compromise the mechanical properties of the final pieces, new techniques to incorporate the fillers into the BC and their effect upon the mechanical properties of BC pieces were investigated in the present study. PMMA powder composites were produced in situ in the reaction vessel by addition of X-ray contrasts to the reacting MMA mixture. It is shown that this can lead to much better mechanical properties of test pieces, when compared to standard bone cement formulations, because enhanced dispersion of the radiopaque agents can be achieved. Moreover, it is shown that the addition of hydroxyapatite (HA) and acrylic acid (AA) to the bone cement recipe can be beneficial for the mechanical performance of the final material. It is also shown that particle morphology can exert a tremendous effect upon the performance of test pieces, indicating that the suspension polymerization step should be carefully controlled when optimization of the bone cement formulation is desired. (author)

  12. Production of bone cement composites: effect of fillers, co-monomer and particles properties

    Directory of Open Access Journals (Sweden)

    J. G. F. Santos Jr.

    2011-06-01

    Full Text Available Artificial bone cements (BCs based on poly(methyl methacrylate (PMMA powders and methyl methacrylate (MMA liquid monomer also present in their formulation small amounts of other substances, including a chemical initiator compound and radiopaque agents. Because inadequate mixing of the recipe components during the manufacture of the bone cement may compromise the mechanical properties of the final pieces, new techniques to incorporate the fillers into the BC and their effect upon the mechanical properties of BC pieces were investigated in the present study. PMMA powder composites were produced in-situ in the reaction vessel by addition of X-ray contrasts to the reacting MMA mixture. It is shown that this can lead to much better mechanical properties of test pieces, when compared to standard bone cement formulations, because enhanced dispersion of the radiopaque agents can be achieved. Moreover, it is shown that the addition of hydroxyapatite (HA and acrylic acid (AA to the bone cement recipe can be beneficial for the mechanical performance of the final material. It is also shown that particle morphology can exert a tremendous effect upon the performance of test pieces, indicating that the suspension polymerization step should be carefully controlled when optimization of the bone cement formulation is desired.

  13. Heavy metal toxicity and bioavailability of dissolved nutrients to a bacterivorous flagellate are linked to suspended particle physical properties

    International Nuclear Information System (INIS)

    Boenigk, Jens; Wiedlroither, Anneliese; Pfandl, Karin

    2005-01-01

    Many dissolved substances attach easily to sediment particles. In the presence of suspended sediments bioavailability of dissolved substances is therefore, usually reduced and clays are even applied to 'wash' natural waters upon pollution. In organisms which feed on food organisms in the size range of these suspended sediment particles, however, bioavailability of such substances may even increase. For microorganisms the interaction with dissolved substances and suspended sediment particles so far has hardly been investigated. We specifically tested: (1) the importance of suspended particles as an uptake route for dissolved substances; and (2) the significance of particle surface properties, i.e. surface load and mineralogy. As a model system we used an axenically cultured strain of a widespread and often abundant flagellate ('Spumella-like' flagellate strain JBM10). We tested the toxicity of cadmium (II) and mercury (II) as well as availability of dissolved organic matter (DOM) in the absence as well as in the presence of different natural clays, i.e. a kaolinite, a montmorillonite, and a mixed clay, and of artificial silicate particles of different surface charge. When applied separately the presence of the heavy metals cadmium and mercury as well as of suspended particles negatively affected the investigated flagellate but nutritive organics supported growth of the investigated flagellate. Toxic stress response comprises behavioral changes including enhanced swimming activity and stress egestion of ingested particles and was generally similar for a variety of different flagellate species. In combination with suspended particles, the respective effect of trace metals and nutritive substances decreased. Regarding the particle quality, cadmium toxicity increased with increasingly negative surface charge, i.e. increasing surface density of silanol groups (Pearson's product moment, P = 0.005). For mercury particle mineralogy still had a significant effect (P < 0

  14. Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

    Directory of Open Access Journals (Sweden)

    M. Ehn

    2007-01-01

    Full Text Available The hygroscopic growth of aerosol particles present in a boreal forest was measured at a relative humidity of 88%. Simultaneously the gas phase concentration of sulfuric acid, a very hygroscopic compound, was monitored. The focus was mainly on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF correlated positively with the gaseous phase sulfuric acid concentrations. The smaller the particles, the stronger the correlation, with r=0.20 for 50 nm and r=0.50 for 10 nm particles. The increase in GF due to condensing sulfuric acid is expected to be larger for particles with initially smaller masses. During new particle formation, the changes in solubility of the new particles were calculated during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that the initial particle growth was due to more hygroscopic compounds, whereas the later growth during the evening and night was mainly caused by less hygroscopic or even hydrophobic compounds. For all the measured sizes, a diurnal variation in GF was observed both during days with and without particle formation. The GF was lowest at around midnight, with a mean value of 1.12–1.24 depending on particle size and if new particle formation occurred during the day, and increased to 1.25–1.34 around noon. This can be tentatively explained by day- and nighttime gas-phase chemistry; different vapors will be present depending on the time of day, and through condensation these compounds will alter the hygroscopic properties of the particles in different ways.

  15. Mechanical and thermal properties of bio-composites based on polypropylene reinforced with Nut-shells of Argan particles

    International Nuclear Information System (INIS)

    Essabir, H.; Hilali, E.; Elgharad, A.; El Minor, H.; Imad, A.; Elamraoui, A.; Al Gaoudi, O.

    2013-01-01

    Highlights: ► Nuts-shells of Argan particles are used as reinforcement in thermoplastic matrix. ► Particles are homogeneously dispersed and distributed within PP matrix. ► Mechanical and thermal characterization of the composite are applied. ► Particles–matrix adhesion was assured by the use of a SBS compatibilizer. - Abstract: This study treats the combined effects of both particle sizes and particle loading on the mechanical and thermal properties of polypropylene (PP) composites reinforced with Nut-shells of Argan (NA) particles. Three range sizes of particles were used in the presence of a polypropylene matrix grafted with 8 wt.% of a linear block copolymer based on styrene and butadiene coupling agent, to improve adhesion between the particles and the matrix. The composites were prepared through melt-blending using an internal mixer and the tensile specimens were prepared using a hot press molding machine. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and tensile tests were employed to characterize the composites at 10, 15, 20 and 25 wt.% particle contents. Results show a clear improvement in Young’s modulus from the use of particles when compared to the neat PP, a gain of 42.65%, 26.7% and 2.9% at 20 wt.% particle loading, for particle range 1, 2 and 3, respectively. In addition a notable increase in the Young’s modulus was observed when decrease the particle size. The thermal stability of composites exhibits a slight decrease (256–230 °C) with particles loading from 10 to 25 wt.%, against neat PP (258 °C)

  16. Experimental investigation of the effect of inlet particle properties on the capture efficiency in an exhaust particulate filter

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Sandeep; Rothamer, David; Zelenyuk, Alla; Stewart, Mark; Bell, David

    2017-11-01

    The impact of inlet particle properties on the filtration performance of clean and particulate matter (PM) laden cordierite filter samples was evaluated using PM generated by a spark-ignition direct-injection (SIDI) engine fuelled with tier II EEE certification gasoline. Prior to the filtration experiments, a scanning mobility particle spectrometer (SMPS) was used to measure the electrical-mobility based particle size distribution (PSD) in the SIDI exhaust from distinct engine operating conditions. An advanced aerosol characterization system that comprised of a centrifugal particle mass analyser (CPMA), a differential mobility analyser (DMA), and a single particle mass spectrometer (SPLAT II) was used to obtain additional information on the SIDI particulate, including particle composition, mass, and dynamic shape factors (DSFs) in the transition () and free-molecular () flow regimes. During the filtration experiments, real-time measurements of PSDs upstream and downstream of the filter sample were used to estimate the filtration performance and the total trapped mass within the filter using an integrated particle size distribution method. The filter loading process was paused multiple times to evaluate the filtration performance in the partially loaded state. The change in vacuum aerodynamic diameter () distribution of mass-selected particles was examined for flow through the filter to identify whether preferential capture of particles of certain shapes occurred in the filter. The filter was also probed using different inlet PSDs to understand their impact on particle capture within the filter sample. Results from the filtration experiment suggest that pausing the filter loading process and subsequently performing the filter probing experiments did not impact the overall evolution of filtration performance. Within the present distribution of particle sizes, filter efficiency was independent of particle shape potentially due to the diffusion-dominant filtration

  17. Effect of nanoclay particles on some physical and mechanical properties of soils

    Directory of Open Access Journals (Sweden)

    H Sharifnasab

    2016-04-01

    Full Text Available Introduction: As a mechanical tillage practices on soil preparation improve soil structure, increase in porosity, better distribution of soil aggregates and eventually modify the physical properties of soil. The use of nano-technology in agricultural science and its application in tillage for improving the physical properties and mechanical issues has grown substantially. Nanotechnology is an appropriate way to reduce soil limitations. However the nanoparticles are very small amounts in soil, due to features such as high surface area, surface charge (appearance and sometimes porous nano-engineering of physical-chemical properties of soil are affected significantly (Mohammadi & Niazian, 2013. To use of nanomaterials in the territory of a new issue (Taipodia et al., 2011. Small developments on the use of nanoparticles to improve soil quality and land reform have been taken (Theron et al., 2008. Clay soil was used to enhance the compressive strength (Yonekura & Miwa, 1993. Nanosilica particle effects were examined for increasing resistance against penetration and consolidation (Noll et al., 1992. In 2005, these particles were used to increase adhesion and reduce viscosity. It seemed that the adhesion of the particles was depended on Nanosilica (Mohammadi & Niazian, 2013. The use of nanomaterials showed that the increased pH and soil fertility, improved soil physical structure, and reduced mobility, availability and toxicity of heavy metals and other environmental factors and those that will stabilize the soil components and subsides the erosion in the mining pick, (Lal, 2008. In agriculture, the soil conditioner studies have shown that nanoparticles can mine the soil quality by increasing water-holding capacity, increasing silt and clay and improve levels of nutrients, and eliminate toxins, (Liu and Lal, 2012.In this study, the effect on some physical and mechanical properties of soil contain clay gradation, Atterberg limits, specifications

  18. On The Importance of Connecting Laboratory Measurements of Ice Crystal Growth with Model Parameterizations: Predicting Ice Particle Properties

    Science.gov (United States)

    Harrington, J. Y.

    2017-12-01

    Parameterizing the growth of ice particles in numerical models is at an interesting cross-roads. Most parameterizations developed in the past, including some that I have developed, parse model ice into numerous categories based primarily on the growth mode of the particle. Models routinely possess smaller ice, snow crystals, aggregates, graupel, and hail. The snow and ice categories in some models are further split into subcategories to account for the various shapes of ice. There has been a relatively recent shift towards a new class of microphysical models that predict the properties of ice particles instead of using multiple categories and subcategories. Particle property models predict the physical characteristics of ice, such as aspect ratio, maximum dimension, effective density, rime density, effective area, and so forth. These models are attractive in the sense that particle characteristics evolve naturally in time and space without the need for numerous (and somewhat artificial) transitions among pre-defined classes. However, particle property models often require fundamental parameters that are typically derived from laboratory measurements. For instance, the evolution of particle shape during vapor depositional growth requires knowledge of the growth efficiencies for the various axis of the crystals, which in turn depends on surface parameters that can only be determined in the laboratory. The evolution of particle shapes and density during riming, aggregation, and melting require data on the redistribution of mass across a crystals axis as that crystal collects water drops, ice crystals, or melts. Predicting the evolution of particle properties based on laboratory-determined parameters has a substantial influence on the evolution of some cloud systems. Radiatively-driven cirrus clouds show a broader range of competition between heterogeneous nucleation and homogeneous freezing when ice crystal properties are predicted. Even strongly convective squall

  19. Characterizing physical properties and heterogeneous chemistry of single particles in air using optical trapping-Raman spectroscopy

    Science.gov (United States)

    Gong, Z.; Wang, C.; Pan, Y. L.; Videen, G.

    2017-12-01

    Heterogeneous reactions of solid particles in a gaseous environment are of increasing interest; however, most of the heterogeneous chemistry studies of airborne solids were conducted on particle ensembles. A close examination on the heterogeneous chemistry between single particles and gaseous-environment species is the key to elucidate the fundamental mechanisms of hydroscopic growth, cloud nuclei condensation, secondary aerosol formation, etc., and reduce the uncertainty of models in radiative forcing, climate change, and atmospheric chemistry. We demonstrate an optical trapping-Raman spectroscopy (OT-RS) system to study the heterogeneous chemistry of the solid particles in air at single-particle level. Compared to other single-particle techniques, optical trapping offers a non-invasive, flexible, and stable method to isolate single solid particle from substrates. Benefited from two counter-propagating hollow beams, the optical trapping configuration is adaptive to trap a variety of particles with different materials from inorganic substitution (carbon nanotubes, silica, etc.) to organic, dye-doped polymers and bioaerosols (spores, pollen, etc.), with different optical properties from transparent to strongly absorbing, with different sizes from sub-micrometers to tens of microns, or with distinct morphologies from loosely packed nanotubes to microspheres and irregular pollen grains. The particles in the optical trap may stay unchanged, surface degraded, or optically fragmented according to different laser intensity, and their physical and chemical properties are characterized by the Raman spectra and imaging system simultaneously. The Raman spectra is able to distinguish the chemical compositions of different particles, while the synchronized imaging system can resolve their physical properties (sizes, shapes, morphologies, etc.). The temporal behavior of the trapped particles also can be monitored by the OT-RS system at an indefinite time with a resolution from

  20. The effect of fast particles' irradiation on electrooptical properties of GaP LEDs

    International Nuclear Information System (INIS)

    Gontaruk, O.; Kovalenko, A.; Malyj, E.; Petrenko, I.; Pinkovska, M.; Polivtcev, L.; Tartachnyk, V.

    2013-01-01

    The electrooptical properties of industrial AL 102 GaP light-emitting diodes (LEDs) irradiated with fast particles have been studied. 2 MeV electrons and fast reactor neutrons were used and devices' microplsma emitting, current-voltage and capacitance-voltage characteristics were measured. It was shown that electron irradiation in the range (2-5)10 16 cm -2 leads to the drop of microplasma emitting intensity, decrease of capacity and reverse currents and increase of reverse bias. The annealing study of current-voltage characteristics after neutron irradiation of diodes confirms the assumption about prevailing radiation influence on diode base due to induce of deep levels. (authors)

  1. Effect of Modified Rubber Particles Mixing Amount on Properties of Cement Mortar

    Directory of Open Access Journals (Sweden)

    Gang Xue

    2017-01-01

    Full Text Available The crumb rubber cement mortar is prepared by the crumb rubber aggregates in 60 mesh which are modified by 1% polyvinyl alcohol (PVA solution. Some mechanical properties of cement mortar with different crumb rubber aggregate amounts are researched including compressive strength, flexural strength, the ratio of compressive strength to flexural strength, impact resistance, and dry contraction percentage. In our tests, we consider six kinds of the rubber contents, 0%, 7.5%, 15%, 19%, 22.5%, and 30%, respectively. The optimal mixing amount of crumb rubber is determined by measuring three indices, the ratio of compressive strength to flexural strength, impact resistance, and dry contraction percentage. It is shown by test that the ratio of compressive strength to flexural strength is the smallest when the mixing amount of rubber is 19%; meanwhile high impact resistance and rational drying shrinkage are observed. The optimal mixing amount of the rubber particles is 19% determined by this test.

  2. Properties of amorphous silicon thin films synthesized by reactive particle beam assisted chemical vapor deposition

    International Nuclear Information System (INIS)

    Choi, Sun Gyu; Wang, Seok-Joo; Park, Hyeong-Ho; Jang, Jin-Nyoung; Hong, MunPyo; Kwon, Kwang-Ho; Park, Hyung-Ho

    2010-01-01

    Amorphous silicon thin films were formed by chemical vapor deposition of reactive particle beam assisted inductively coupled plasma type with various reflector bias voltages. During the deposition, the substrate was heated at 150 o C. The effects of reflector bias voltage on the physical and chemical properties of the films were systematically studied. X-ray diffraction and Raman spectroscopy results showed that the deposited films were amorphous and the films under higher reflector voltage had higher internal energy to be easily crystallized. The chemical state of amorphous silicon films was revealed as metallic bonding of Si atoms by using X-ray photoelectron spectroscopy. An increase in reflector voltage induced an increase of surface morphology of films and optical bandgap and a decrease of photoconductivity.

  3. Investigating fundamental properties of wind turbine wake structure using particle image velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Whale, J. [Univ. of Edinburgh, Dept. of Mechanical Engineering, Edinburgh (United Kingdom)

    1997-08-01

    Low Reynolds number flow visualization tests are often used for showing the flow pattern changes associated with changes in lift-coefficients at a higher Reynolds number. In wind turbine studies, analysis of measured wake structures at small scale may reveal fundamental properties of the wake which will offer wake modellers a more complete understanding of rotor flows. Measurements are presented from experiments on a model wind turbine rig conducted in a water channel. The laser-optics technique of Particle Image Velocimetry (PIV) is used to make simultaneous multi-point measurements of the wake flow behind small-scale rotors. Analysis of the PIV data shows trends in velocity and vorticity structure in the wake. Study of the flow close to the rotor plane reveals information on stalled flow and blade performance. (au)

  4. THE STRUCTURE AND PROPERTIES OF COMPOSITE LASER CLAD COATINGS WITH Ni BASED MATRIX WITH WC PARTICLES

    Directory of Open Access Journals (Sweden)

    Zita Iždinská

    2010-09-01

    Full Text Available In this work, the influence of the processing conditions on the microstructure and abrasive wear behavior of composite laser clad coatings with Ni based matrix reinforced with 50% WC particles is analyzed. Composite powder was applied in the form of coatings onto a mild steel substrate (Fe–0.17% C by different laser powers and cladding speeds. The microstructure of the coatings was analyzed by scanning electron microscopy (SEM. Tribological properties of coatings were evaluated by pin-on-disc wear test. It appeared that the hardness of the matrix of composite coatings decreases with increasing cladding speed. However, wear resistance of composite coatings with decreasing hardness of Ni based matrix increases. Significantly enhanced wear resistance of WC composite coatings in comparison with Ni based coatings is attributed to the hard phase structures in composite coatings.

  5. Inverse Estimation of Surface Radiation Properties Using Repulsive Particle Swarm Optimization Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyun Ho [Sejong University, Sejong (Korea, Republic of); Kim, Ki Wan [Agency for Defense Development, Daejeon (Korea, Republic of)

    2014-09-15

    The heat transfer mechanism for radiation is directly related to the emission of photons and electromagnetic waves. Depending on the participation of the medium, the radiation can be classified into two forms: surface and gas radiation. In the present study, unknown radiation properties were estimated using an inverse boundary analysis of surface radiation in an axisymmetric cylindrical enclosure. For efficiency, a repulsive particle swarm optimization (RPSO) algorithm, which is a relatively recent heuristic search method, was used as inverse solver. By comparing the convergence rates and accuracies with the results of a genetic algorithm (GA), the performances of the proposed RPSO algorithm as an inverse solver was verified when applied to the inverse analysis of the surface radiation problem.

  6. Inverse Estimation of Surface Radiation Properties Using Repulsive Particle Swarm Optimization Algorithm

    International Nuclear Information System (INIS)

    Lee, Kyun Ho; Kim, Ki Wan

    2014-01-01

    The heat transfer mechanism for radiation is directly related to the emission of photons and electromagnetic waves. Depending on the participation of the medium, the radiation can be classified into two forms: surface and gas radiation. In the present study, unknown radiation properties were estimated using an inverse boundary analysis of surface radiation in an axisymmetric cylindrical enclosure. For efficiency, a repulsive particle swarm optimization (RPSO) algorithm, which is a relatively recent heuristic search method, was used as inverse solver. By comparing the convergence rates and accuracies with the results of a genetic algorithm (GA), the performances of the proposed RPSO algorithm as an inverse solver was verified when applied to the inverse analysis of the surface radiation problem

  7. Influence of particle surface properties on the dielectric behavior of silica/epoxy nanocomposites

    International Nuclear Information System (INIS)

    Cheng Lihong; Zheng Liaoying; Li Guorong; Zeng Jiangtao; Yin Qingrui

    2008-01-01

    Silica/epoxy composites have been widely used in functional electric device applications. Silica nanoparticles, both unmodified and modified with the coupling agent KH-550, were used to prepare epoxy composites. Dielectric measurements showed that nanocomposites exhibit a higher dielectric constant than the control sample, and had more obvious dielectric relaxation characteristics. Results showed that particle surface properties have a profound effect on the dielectric behavior of the nanocomposites. These characteristics are attributed to the local ununiformity of the microstructure caused by the large interface area and the interaction between the filler and the matrix. This phenomenon is explained in terms of prolonging chemical chains created during the curing process. The mechanism is discussed with measurements of X-ray diffraction (XRD) and Fourier transform infrared (FTIR)

  8. Preparation and Hydrogen Storage Properties of Mg-Rich Mg-Ni Ultrafine Particles

    Directory of Open Access Journals (Sweden)

    Jianxin Zou

    2012-01-01

    Full Text Available In the present work, Mg-rich Mg-Ni ultrafine powders were prepared through an arc plasma method. The phase components, microstructure, and hydrogen storage properties of the powders were carefully investigated. It is found that Mg2Ni and MgNi2 could be obtained directly from the vapor state reactions between Mg and Ni, depending on the local vapor content in the reaction chamber. A nanostructured MgH2 + Mg2NiH4 hydrogen storage composite could be generated after hydrogenation of the Mg-Ni ultrafine powders. After dehydrogenation, MgH2 and Mg2NiH4 decomposed into nanograined Mg and Mg2Ni, respectively. Thermogravimetry/differential scanning calorimetry (TG/DSC analyses showed that Mg2NiH4 phase may play a catalytic role in the dehydriding process of the hydrogenated Mg ultrafine particles.

  9. The effect of particle properties on the depth profile of buoyant plastics in the ocean

    Science.gov (United States)

    Kooi, Merel; Reisser, Julia; Slat, Boyan; Ferrari, Francesco F.; Schmid, Moritz S.; Cunsolo, Serena; Brambini, Roberto; Noble, Kimberly; Sirks, Lys-Anne; Linders, Theo E. W.; Schoeneich-Argent, Rosanna I.; Koelmans, Albert A.

    2016-10-01

    Most studies on buoyant microplastics in the marine environment rely on sea surface sampling. Consequently, microplastic amounts can be underestimated, as turbulence leads to vertical mixing. Models that correct for vertical mixing are based on limited data. In this study we report measurements of the depth profile of buoyant microplastics in the North Atlantic subtropical gyre, from 0 to 5 m depth. Microplastics were separated into size classes (0.5-1.5 and 1.5-5.0 mm) and types (‘fragments’ and ‘lines’), and associated with a sea state. Microplastic concentrations decreased exponentially with depth, with both sea state and particle properties affecting the steepness of the decrease. Concentrations approached zero within 5 m depth, indicating that most buoyant microplastics are present on or near the surface. Plastic rise velocities were also measured, and were found to differ significantly for different sizes and shapes. Our results suggest that (1) surface samplers such as manta trawls underestimate total buoyant microplastic amounts by a factor of 1.04-30.0 and (2) estimations of depth-integrated buoyant plastic concentrations should be done across different particle sizes and types. Our findings can assist with improving buoyant ocean plastic vertical mixing models, mass balance exercises, impact assessments and mitigation strategies.

  10. Effect of carbide particles on the ablation properties of tungsten composites

    International Nuclear Information System (INIS)

    Song Guiming; Zhou Yu; Wang Yujin

    2003-01-01

    The high temperature ablation behavior of tungsten composites containing carbides produced by vacuum hot pressing is studied as a function of reinforcement chemistry (ZrC and TiC) and content using a self-made oxyacetylene ablation equipment. A dynamic responding multiwavelength pyrometer was employed to measure the temperature of the ablation surface, and a thermocouple was employed to measure the temperature of the back surface during the time that a specimen was being ablated. The mass and linear ablation rates are lower in composites containing ZrC, decreasing with increasing particle content in both composites system. The values of the mass and linear ablation rates were in the order from high to low: W>30TiC/W>40TiC/W>30ZrC/W>40ZrC/W (30TiC/W stands for 30 vol.% TiC particle content in the W matrix, the same below). The important temperature curves of the ablation surfaces of specimens were successfully detected online. Ablated surfaces and vertical sections of the specimens were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Thermochemical oxidation of tungsten, TiC, and ZrC was the main ablation mechanism of ZrC/W and TiC/W composites. These ablation behaviors are discussed based on the thermophysical and chemical properties of both the composite systems

  11. Properties of Arctic Aerosol Particles and Residuals of Warm Clouds: Cloud Activation Efficiency and the Aerosol Indirect Effect

    Science.gov (United States)

    Zelenyuk, A.; Imre, D. G.; Leaitch, R.; Ovchinnikov, M.; Liu, P.; Macdonald, A.; Strapp, W.; Ghan, S. J.; Earle, M. E.

    2012-12-01

    Single particle mass spectrometer, SPLAT II, was used to characterize the size, composition, number concentration, density, and shape of individual Arctic spring aerosol. Background particles, particles above and below the cloud, cloud droplet residuals, and interstitial particles were characterized with goal to identify the properties that separate cloud condensation nuclei (CCN) from background aerosol particles. The analysis offers a comparison between warm clouds formed on clean and polluted days, with clean days having maximum particle concentrations (Na) lower than ~250 cm-3, as compared with polluted days, in which maximum concentration was tenfold higher. On clean days, particles were composed of organics, organics mixed with sulfates, biomass burning (BB), sea salt (SS), and few soot and dust particles. On polluted days, BB, organics associated with BB, and their mixtures with sulfate dominated particle compositions. Based on the measured compositions and size distributions of cloud droplet residuals, background aerosols, and interstitial particles, we conclude that these three particle types had virtually the same compositions, which means that cloud activation probabilities were surprisingly nearly composition independent. Moreover, these conclusions hold in cases in which less than 20% or more than 90% of background particles got activated. We concluded that for the warm clouds interrogated in this study particle size played a more important factor on aerosol CCN activity. Comparative analysis of all studied clouds reveals that aerosol activation efficiency strongly depends on the aerosol concentrations, such that at Na <200 cm-3, nearly all particles activate, and at higher concentrations the activation efficiency is lower. For example, when Na was greater than 1500 cm-3, less than ~30% of particles activated. The data suggest that as the number of nucleated droplets increases, condensation on existing droplets effectively competes with particle

  12. Microphysical and optical properties of aerosol particles in urban zone during ESCOMPTE

    Science.gov (United States)

    Mallet, M.; Roger, J. C.; Despiau, S.; Dubovik, O.; Putaud, J. P.

    2003-10-01

    Microphysical and optical properties of the main aerosol species on a peri-urban site have been investigated during the ESCOMPTE experiment. Ammonium sulfate (AS), nitrate (N), black carbon (BC), particulate organic matter (POM), sea salt (SS) and mineral aerosol (D) size distributions have been used, associated with their refractive index, to compute, from the Mie theory, the key radiative aerosol properties as the extinction coefficient Kext, the mass extinction efficiencies σext, the single scattering albedo ω0 and the asymmetry parameter g at the wavelength of 550 nm. Optical computations show that 90% of the light extinction is due to anthropogenic aerosol and only 10% is due to natural aerosol (SS and D). 44±6% of the extinction is due to (AS) and 40±6% to carbonaceous particles (20±4% to BC and 21±4% to POM). Nitrate aerosol has a weak contribution of 5±2%. Computations of the mass extinction efficiencies σext, single scattering albedo ω0 and asymmetry parameter g indicate that the optical properties of the anthropogenic aerosol are often quite different from those yet published and generally used in global models. For example, the (AS) mean specific mass extinction presents a large difference with the value classically adopted at low relative humidity ( h<60%) (2.6±0.5 instead of 6 m 2 g -1 at 550 nm). The optical properties of the total aerosol layer, including all the aerosol species, indicate a mean observed single-scattering albedo ω0=0.85±0.05, leading to an important absorption of the solar radiation and an asymmetry parameter g=0.59±0.05 which are in a reasonably good agreements with the AERONET retrieval of ω0 (=0.86±0.05) and g (=0.64±0.05) at this wavelength.

  13. Improving the particle distribution and mechanical properties of friction-stir-welded composites by using a smooth pin tool

    Science.gov (United States)

    Liu, Huijie; Hu, Yanying; Zhao, Yunqiang; Fujii, Hidetoshi

    2017-09-01

    Friction stir welding (FSW) is a very promising technique for joining particle-reinforced aluminum-matrix composites (PRAMCs), but with increase in the volume fraction of reinforcing particles, their distribution in welds becomes inhomogeneous. This leads to an inconsistent deformation of welds and their destruction at low stresses. In order to improve the weld microstructure, a smooth pin tool was used for the friction stir welding of AC4A + 30 vol.% SiC particle-reinforced aluminum-matrix composites. The present work describes the effect of welding parameters on the characteristics of particle distribution and the mechanical properties of welds. The ultimate strength of weld reached, 309 MPa, was almost 190% of that of the basic material. The mechanism of SiC particle conglomeration is clearly illustrated by means of schematic illustrations.

  14. Defatted wheat germ application: Influence on cookies' properties with regard to its particle size and dough moisture content.

    Science.gov (United States)

    Petrović, Jovana; Rakić, Dušan; Fišteš, Aleksandar; Pajin, Biljana; Lončarević, Ivana; Tomović, Vladimir; Zarić, Danica

    2017-10-01

    The introduction of agro-food industry by-products rich in bioactive compounds represents major challenge in food industry sector. The influence of wheat germ particle size (Box-Behnken experimental design. The substitution of wheat flour with wheat germ increased the protein, fat, mineral, and fiber content of the cookies. The particle size of wheat germ affected the textural properties of cookies. As the particle size of wheat germ increased, the hardness of cookies decreased. The color of the cookie was most influenced by the interaction of dough moisture content and wheat germ particle size. Wheat germ level up to 15% had no significant effect on the sensory characteristics of cookies. A suitable combination of defatted wheat germ level, its particle size, and dough moisture content can improve the nutritional value of cookies, without causing a negative effect on the cookies' sensory characteristics.

  15. Effects of Eutectic Si Particles on Mechanical Properties and Fracture Toughness of Cast A356 Aluminum Alloys

    International Nuclear Information System (INIS)

    Lee, Kyu Hong; Lee, Sung Hak; Kwon, Yong Nam

    2007-01-01

    The present study aims at investigating the effects of eutectic Si particles on mechanical properties and fracture toughness of three A356 aluminum alloys. These A356 alloys were fabricated by casting processes such as rheo-casting, squeeze-casting, and casting-forging, and their mechanical properties and fracture toughness were analyzed in relation with microfracture mechanism study. All the cast A356 alloys contained eutectic Si particles mainly segregated along solidification cells, and the distribution of Si particles was modified by squeeze-casting and casting-forging processes. Microfracture observation results showed that eutectic Si particles segregated along cells were cracked first, but that aluminum matrix played a role in blocking crack propagation. Tensile properties and fracture toughness of the squeeze cast and cast-forged alloys having homogeneous distribution of eutectic Si particles were superior to those of the rheo-cast alloy. In particular, the cast-forged alloy had excellent hardness, strength, ductility, and fracture toughness because of the matrix strengthening and homogeneous distribution of eutectic Si particles due to forging process

  16. The effect of Co particle structures on the mechanical properties and microstructure of TiCN-based cermets

    International Nuclear Information System (INIS)

    Deng, Y.; Jiang, X.Q.; Zhang, Y.H.; Chen, H.; Tu, M.J.; Deng, L.; Zou, J.P.

    2016-01-01

    Ti(C,N) based cermets are composite materials composed of a hard phase and a binder phase structure. Cubic-structured Co particles are the best choice for the binder phase of Ti(C,N) based cermets due to their excellent toughness performance. However, the application of β-Co particles in cermets has not been reported in the literature so far. In this pioneer study, ultrafine Ti(C,N) based cermet samples were prepared by separately using Co particles of different structures as the binder phase, and the effect of the Co particle structures on the mechanical properties and microstructure of the cermets were studied: First, the Empirical Electron Theory was used to calculate the difference in the interface density (∆ρ) for different crystals, and the interface combined strength between the hard phase of different structures containing Co particles were evaluated. Second, we systematically investigated the evolution of the microstructures of the two cermets during the sintering process, and evaluated the characteristics of the microstructure (which determines the properties of the cermets). Finally, the mechanical properties of the samples were tested, and the performances of the Co structures were evaluated. The results show that β-Co particles can optimize the cermet microstructure, which leads to excellent mechanical performance.

  17. The effect of Co particle structures on the mechanical properties and microstructure of TiCN-based cermets

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Y. [Chongqing University of Arts and Science, Chongqing 402160 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Jiang, X.Q. [Southwest University, Chongqing Academy Science and Technology, Chongqing 4100715 (China); Zhang, Y.H.; Chen, H.; Tu, M.J. [Chongqing University of Arts and Science, Chongqing 402160 (China); Deng, L., E-mail: dengying.163@163.com [Chengdu Chengliang Tool Group Co., Ltd., Chengdu 610056 (China); Zou, J.P., E-mail: 1042551842@qq.com [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2016-10-15

    Ti(C,N) based cermets are composite materials composed of a hard phase and a binder phase structure. Cubic-structured Co particles are the best choice for the binder phase of Ti(C,N) based cermets due to their excellent toughness performance. However, the application of β-Co particles in cermets has not been reported in the literature so far. In this pioneer study, ultrafine Ti(C,N) based cermet samples were prepared by separately using Co particles of different structures as the binder phase, and the effect of the Co particle structures on the mechanical properties and microstructure of the cermets were studied: First, the Empirical Electron Theory was used to calculate the difference in the interface density (∆ρ) for different crystals, and the interface combined strength between the hard phase of different structures containing Co particles were evaluated. Second, we systematically investigated the evolution of the microstructures of the two cermets during the sintering process, and evaluated the characteristics of the microstructure (which determines the properties of the cermets). Finally, the mechanical properties of the samples were tested, and the performances of the Co structures were evaluated. The results show that β-Co particles can optimize the cermet microstructure, which leads to excellent mechanical performance.

  18. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

    Directory of Open Access Journals (Sweden)

    C. H. Twohy

    2013-03-01

    Full Text Available The southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles on the stratocumulus deck was investigated during the VOCALS field experiment. Aerosol measurements below and above cloud were made with a ultra-high sensitivity aerosol spectrometer and analytical electron microscopy. In addition to more standard in-cloud measurements, droplets were collected and evaporated using a counterflow virtual impactor (CVI, and the non-volatile residual particles were analyzed. Many flights focused on the gradient in cloud properties on an E-W track along 20° S from near the Chilean coast to remote areas offshore. Mean statistics, including their significance, from eight flights and many individual legs were compiled. Consistent with a continental source of cloud condensation nuclei, below-cloud accumulation-mode aerosol and droplet number concentration generally decreased from near shore to offshore. Single particle analysis was used to reveal types and sources of the enhanced particle number that influence droplet concentration. While a variety of particle types were found throughout the region, the dominant particles near shore were partially neutralized sulfates. Modeling and chemical analysis indicated that the predominant source of these particles in the marine boundary layer along 20° S was anthropogenic pollution from central Chilean sources, with copper smelters a relatively small contribution. Cloud droplets were smaller in regions of enhanced particles near shore. However, physically thinner clouds, and not just higher droplet number concentrations from pollution, both contributed to the smaller droplets. Satellite measurements were used to show that cloud albedo was highest 500–1000 km offshore, and actually slightly lower closer to shore due to the generally thinner clouds and lower

  19. Dynamic properties of polydisperse colloidal particles in the presence of thermal gradient studied by a modified Brownian dynamic model

    Science.gov (United States)

    Song, Dongxing; Jin, Hui; Jing, Dengwei; Wang, Xin

    2018-03-01

    Aggregation and migration of colloidal particles under the thermal gradient widely exists in nature and many industrial processes. In this study, dynamic properties of polydisperse colloidal particles in the presence of thermal gradient were studied by a modified Brownian dynamic model. Other than the traditional forces on colloidal particles, including Brownian force, hydrodynamic force, and electrostatic force from other particles, the electrostatic force from the asymmetric ionic diffusion layer under a thermal gradient has been considered and introduced into the Brownian dynamic model. The aggregation ratio of particles (R A), the balance time (t B) indicating the time threshold when {{R}A} becomes constant, the porosity ({{P}BA} ), fractal dimension (D f) and distributions of concentration (DISC) and aggregation (DISA) for the aggregated particles were discussed based on this model. The aggregated structures formed by polydisperse particles are less dense and the particles therein are loosely bonded. Also it showed a quite large compressibility as the increases of concentration and interparticle potential can significantly increase the fractal dimension. The thermal gradient can induce two competitive factors leading to a two-stage migration of particles. When t{{t}B} , the thermophoresis becomes dominant thus the migrations of particles are against the thermal gradient. The effect of thermophoresis on the aggregate structures was found to be similar to the effect of increasing particle concentration. This study demonstrates how the thermal gradient affects the aggregation of monodisperse and polydisperse particles and can be a guide for the biomimetics and precise control of colloid system under the thermal gradient. Moreover, our model can be easily extended to other more complex colloidal systems considering shear, temperature fluctuation, surfactant, etc.

  20. Oriented particleboard made from tali bamboo (Gigantochloa Apus): effect of particle length on physical and mechanical properties

    Science.gov (United States)

    Iswanto, A. H.

    2018-02-01

    Strength properties are one of the problems of particleboard. The objective of this research was to analyze the effect of particle length on physical and mechanical properties oriented particleboard (OPB). The variation particle length size in this experiment namely 3, 5, and 7 cm. The width and thickness size of all bamboo particles were 1 and 0.1 cm respectively. 12% mixed resin of UF and MDI (70/30 %w/w) used for binding. Board size fabricated in 25 by 25 cm2 with thickness and density target of 1 cm and 0.75 gcm-3. The OPB layers for face and back layers aligned perpendicular to the core layer. The weight ratio of the face-to-core-to-back layers were set at 1:2:1. Mat was pressed at 160 °C under 30 kgcm-2 as the pressure for 10 minutes. The results showed that 7 cm length particle produced of the best strength and dimensional stability. The increase of particle length resulted in increasing of strength properties. Over all the parameters of physical and mechanical properties fulfill requirements of JIS A 5908 (2003) excepted of thickness swelling and modulus of elasticity.

  1. Effect of polyacrylamide on morphology and electromagnetic properties of chrysanthemum-like ZnO particles

    International Nuclear Information System (INIS)

    Jun-Feng, Yan; Zhi-Yong, Zhang; Tian-Gui, You; Wu, Zhao; Jiang-Ni, Yun; Fu-Chun, Zhang

    2009-01-01

    Through hydrothermal process, the chrysanthemum-like ZnO particles are prepared with zinc acetate dihydrate (Zn(CH 3 COO) 2 ·2H 2 O) and sodium hydroxide (NaOH) used as main resources under the different concentrations of surfactant polyacrylamide (PAM). The microstructure, morphology and the electromagnetic properties of the as-prepared products are characterized by high-resolution transmissïon electron microscopy (HRTEM), field emission environment scanning electron microscope (FEESEM) and microwave vector network analyzer, respectively. The experimental results indicate that the as-prepared products are ZnO single crystalline with hexagona wurtzite structure, that the values of slenderness ratio L d are different in different PAM concentrations, and that the good magnetic loss property is found in the ZnO products, and the average magnetic loss tangent tan δ u increases with PAM concentration increasing, while the dielectric loss tangent tan δ e decreases. (cross-disciplinary physics and related areas of science and technology)

  2. DEFLECTIONS OF FAST CORONAL MASS EJECTIONS AND THE PROPERTIES OF ASSOCIATED SOLAR ENERGETIC PARTICLE EVENTS

    International Nuclear Information System (INIS)

    Kahler, S. W.; Akiyama, S.; Gopalswamy, N.

    2012-01-01

    The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The original idea was that a CH lying between the solar SEP source region and the magnetic footpoint of the 1 AU observer would result in a delay in onset and/or a decrease in the peak intensity of that SEP event. Recently, Gopalswamy et al. showed that CHs near coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven shocks may show variations attributable to CH deflections of the CME trajectories. Here, we use a CH magnetic force parameter to examine possible effects of CHs on the timing and intensities of 41 observed gradual E ∼ 20 MeV SEP events with CME source regions within 20° of CM. We find no systematic CH effects on SEP event intensity profiles. Furthermore, we find no correlation between the CME leading-edge measured position angles and SEP event properties, suggesting that the widths of CME-driven shock sources of the SEPs are much larger than the CMEs. Independently of the SEP event properties, we do find evidence for significant CME deflections by CH fields in these events.

  3. DEFLECTIONS OF FAST CORONAL MASS EJECTIONS AND THE PROPERTIES OF ASSOCIATED SOLAR ENERGETIC PARTICLE EVENTS

    Energy Technology Data Exchange (ETDEWEB)

    Kahler, S. W. [Air Force Research Laboratory, Space Vehicles Directorate, 3550 Aberdeen Avenue, Kirtland AFB, NM 87117 (United States); Akiyama, S. [Institute for Astrophyics and Computational Sciences, Catholic University of America, Washington, DC 20064 (United States); Gopalswamy, N., E-mail: AFRL.RVB.PA@kirtland.af.mil [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-08-01

    The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The original idea was that a CH lying between the solar SEP source region and the magnetic footpoint of the 1 AU observer would result in a delay in onset and/or a decrease in the peak intensity of that SEP event. Recently, Gopalswamy et al. showed that CHs near coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven shocks may show variations attributable to CH deflections of the CME trajectories. Here, we use a CH magnetic force parameter to examine possible effects of CHs on the timing and intensities of 41 observed gradual E {approx} 20 MeV SEP events with CME source regions within 20 Degree-Sign of CM. We find no systematic CH effects on SEP event intensity profiles. Furthermore, we find no correlation between the CME leading-edge measured position angles and SEP event properties, suggesting that the widths of CME-driven shock sources of the SEPs are much larger than the CMEs. Independently of the SEP event properties, we do find evidence for significant CME deflections by CH fields in these events.

  4. Deflections of Fast Coronal Mass Ejections and the Properties of Associated Solar Energetic Particle Events

    Science.gov (United States)

    Kahler, S. W.; Akiyama, S.; Gopalswamy, N.

    2012-01-01

    The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The original idea was that a CH lying between the solar SEP source region and the magnetic footpoint of the 1 AU observer would result in a delay in onset and/or a decrease in the peak intensity of that SEP event. Recently, Gopalswamy et al. showed that CHs near coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven shocks may show variations attributable to CH deflections of the CME trajectories. Here, we use a CH magnetic force parameter to examine possible effects of CHs on the timing and intensities of 41 observed gradual E approx 20 MeV SEP events with CME source regions within 20 deg. of CM. We find no systematic CH effects on SEP event intensity profiles. Furthermore, we find no correlation between the CME leading-edge measured position angles and SEP event properties, suggesting that the widths of CME-driven shock sources of the SEPs are much larger than the CMEs. Independently of the SEP event properties, we do find evidence for significant CME deflections by CH fields in these events

  5. Particle Engineering of Excipients for Direct Compression: Understanding the Role of Material Properties.

    Science.gov (United States)

    Mangal, Sharad; Meiser, Felix; Morton, David; Larson, Ian

    2015-01-01

    Tablets represent the preferred and most commonly dispensed pharmaceutical dosage form for administering active pharmaceutical ingredients (APIs). Minimizing the cost of goods and improving manufacturing output efficiency has motivated companies to use direct compression as a preferred method of tablet manufacturing. Excipients dictate the success of direct compression, notably by optimizing powder formulation compactability and flow, thus there has been a surge in creating excipients specifically designed to meet these needs for direct compression. Greater scientific understanding of tablet manufacturing coupled with effective application of the principles of material science and particle engineering has resulted in a number of improved direct compression excipients. Despite this, significant practical disadvantages of direct compression remain relative to granulation, and this is partly due to the limitations of direct compression excipients. For instance, in formulating high-dose APIs, a much higher level of excipient is required relative to wet or dry granulation and so tablets are much bigger. Creating excipients to enable direct compression of high-dose APIs requires the knowledge of the relationship between fundamental material properties and excipient functionalities. In this paper, we review the current understanding of the relationship between fundamental material properties and excipient functionality for direct compression.

  6. Investigating on Effect of Particle Form and Mixing Method on applied Properties Green Composite

    Directory of Open Access Journals (Sweden)

    Sahar Daii

    2014-05-01

    Full Text Available Nowadays Paulownia as the fast growing species has noticed for wood industry in the world. In this research, Paulownia fortuni planted in Shaskolateh forest of Gorgan were studied. Two particle form, flour (60 mesh size and fiber (RMP, L/D= 21/54 were prepared. 60 percent of this material with 37% of HDPE , 3% of MAPE were blended separately. Part from this material by internal mixer and other part by extruder blended. Output was prepared like pellets. Samples were prepared in dimensions of 30cm×30cm×1cm, and nominal density 1 g/cm3 by hot press. The mechanical testing of the panels (flexural, hardness, unnotched impact strength and the physical testing of the panels (thickness swelling and water absorption after 2 & 24 hours immersion in water were measured. The result showed that modulus of rupture, hardness, unnotched impact strength of composite made of fiber-PE were lower than composite made of flour-PE. Flexural elastic modulus of composite made of fiber-PE were higher than flour-PE. Water absorption and thickness swelling of composite made of fiber-PE were higher than flour-PE. Also physical and mechanical properties of composites blended by internal mixer improved in compared composites blended by extruder. Physical and mechanical properties of composite made of fiber-PE blended by internal mixer improved in compared composite made of fiber-PE blended by extruder.

  7. DNA-linked NanoParticle Lattices with Diamond Symmetry: Stability, Shape and Optical Properties

    Science.gov (United States)

    Emamy, Hamed; Tkachenko, Alexei; Gang, Oleg; Starr, Francis

    The linking of nanoparticles (NP) by DNA has been proven to be an effective means to create NP lattices with specific order. Lattices with diamond symmetry are predicted to offer novel photonic properties, but self-assembly of such lattices has proven to be challenging due to the low packing fraction, sensitivity to bond orientation, and local heterogeneity. Recently, we reported an approach to create diamond NP lattices based on the association between anisotropic particles with well-defined tetravalent DNA binding topology and isotropically functionalized NP. Here, we use molecular dynamics simulations to evaluate the Gibbs free energy of these lattices, and thereby determine the stability of these lattices as a function of NP size and DNA stiffness. We also predict the equilibrium shape for the cubic diamond crystallite using the Wulff construction method. Specifically, we predict the equilibrium shape using the surface energy for different crystallographic planes. We evaluate surface energy directly form molecular dynamics simulation, which we correlate with theoretical estimates from the expected number of broken DNA bonds along a facet. Furthermore we study the optical properties of this structure, e.g optical bandgap.

  8. Parametric analysis of the thermodynamic properties for a medium with strong interaction between particles

    International Nuclear Information System (INIS)

    Dubovitskii, V.A.; Pavlov, G.A.; Krasnikov, Yu.G.

    1996-01-01

    Thermodynamic analysis of media with strong interparticle (Coulomb) interaction is presented. A method for constructing isotherms is proposed for a medium described by a closed multicomponent thermodynamic model. The method is based on choosing an appropriate nondegenerate frame of reference in the extended space of thermodynamic variables and provides efficient thermodynamic calculations in a wide range of parameters, for an investigation of phase transitions of the first kind, and for determining both the number of phases and coexistence curves. A number of approximate thermodynamic models of hydrogen plasma are discussed. The approximation corresponding to the n5/2 law, in which the effects of particle attraction and repulsion are taken into account qualitatively, is studied. This approximation allows studies of thermodynamic properties of a substance for a wide range of parameters. In this approximation, for hydrogen at a constant temperature, various properties of the degree of ionization are revealed. In addition, the parameters of the second critical point are found under conditions corresponding to the Jovian interior

  9. Fabrication of BaTiO3/Ni composite particles and their electro-magneto responsive properties

    International Nuclear Information System (INIS)

    Lu, Yaping; Gao, Lingxiang; Wang, Lijuan; Xie, Zunyuan; Gao, Meixiang; Zhang, Weiqiang

    2017-01-01

    Graphical abstract: The spherical BaTiO 3 /Ni particles with excellent structure were made by one-step method through fixing the metal Ni(0) reduced by a specific reducing agent (N 2 H 4 ·H 2 O) on the surface of the BaTiO 3 particles with grain diameter of ∼500 nm. BaTiO 3 /Ni particle has double responses of electric and magnetic field simultaneously. Consequentially, coating magnetic metal on BT particle is proposed an effective method to prepare novel electro-magneto responsive particles and one basis of electro-magneto responsive elastomers. - Highlights: • The BaTiO 3 /Ni composite particles were fabricated. • The content of Ni(0) in nickel sheath is 70.2%. • The BaTiO 3 /Ni particles have double responses of electric and magnetic field. - Abstract: BaTiO 3 (BT)/Ni composite particles were made by one-step method through agglomerating the metal Ni(0) nanoparticles reduced by a specific reducing agent (N 2 H 4 ·H 2 O) on the surface of BT sphere with diameter of ∼500 nm. The BT/Ni composite particles were characterized by the means of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). In BT/Ni particles, pure BT spherical particle was coated with Ni nanoparticles agglomerated on its surface. The average thickness of the Ni sheath was ∼30 nm and the content of Ni(0) and Ni (II) in the sheath were 70.2% and 29.8%, respectively. The responsive effects of BT/Ni particles filled in hydrogel elastomer were investigated by the viscoelastic properties. The results indicate that the BT/Ni particles exhibit electro and magneto coordinated responsive properties (E = 1 kV/mm, H = 0.1 T/mm), which is superior to BT particles with individual electro response.

  10. Fabrication of BaTiO{sub 3}/Ni composite particles and their electro-magneto responsive properties

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yaping [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China); Gao, Lingxiang, E-mail: gaolx@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China); Wang, Lijuan [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China); Xie, Zunyuan, E-mail: zyxie123@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China); Gao, Meixiang [Yulin Vocational and Technical College, Yulin 719000 (China); Zhang, Weiqiang [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China)

    2017-07-15

    Graphical abstract: The spherical BaTiO{sub 3}/Ni particles with excellent structure were made by one-step method through fixing the metal Ni(0) reduced by a specific reducing agent (N{sub 2}H{sub 4}·H{sub 2}O) on the surface of the BaTiO{sub 3} particles with grain diameter of ∼500 nm. BaTiO{sub 3}/Ni particle has double responses of electric and magnetic field simultaneously. Consequentially, coating magnetic metal on BT particle is proposed an effective method to prepare novel electro-magneto responsive particles and one basis of electro-magneto responsive elastomers. - Highlights: • The BaTiO{sub 3}/Ni composite particles were fabricated. • The content of Ni(0) in nickel sheath is 70.2%. • The BaTiO{sub 3}/Ni particles have double responses of electric and magnetic field. - Abstract: BaTiO{sub 3} (BT)/Ni composite particles were made by one-step method through agglomerating the metal Ni(0) nanoparticles reduced by a specific reducing agent (N{sub 2}H{sub 4}·H{sub 2}O) on the surface of BT sphere with diameter of ∼500 nm. The BT/Ni composite particles were characterized by the means of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). In BT/Ni particles, pure BT spherical particle was coated with Ni nanoparticles agglomerated on its surface. The average thickness of the Ni sheath was ∼30 nm and the content of Ni(0) and Ni (II) in the sheath were 70.2% and 29.8%, respectively. The responsive effects of BT/Ni particles filled in hydrogel elastomer were investigated by the viscoelastic properties. The results indicate that the BT/Ni particles exhibit electro and magneto coordinated responsive properties (E = 1 kV/mm, H = 0.1 T/mm), which is superior to BT particles with individual electro response.

  11. Improved electrical properties of cadmium substituted cobalt ferrites nano-particles for microwave application

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Rabia [Institute of Chemical Sciences, Gomal University, D. I. Khan (Pakistan); Hussain Gul, Iftikhar, E-mail: iftikhar.gul@scme.nust.edu.pk [Thermal Transport Laboratory (TTL), Materials Engineering Department, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology - NUST, H-12 Campus, Islamabad (Pakistan); Zarrar, Muhammad [Thermal Transport Laboratory (TTL), Materials Engineering Department, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology - NUST, H-12 Campus, Islamabad (Pakistan); Anwar, Humaira [Islamabad Model College for Girls G-10/2, Islamabad (Pakistan); Khan Niazi, Muhammad Bilal [Department of Chemicals Engineering, SCME, NUST, H-12 Campus, Islamabad (Pakistan); Khan, Azim [Institute of Chemical Sciences, Gomal University, D. I. Khan (Pakistan)

    2016-05-01

    Cadmium substituted cobalt ferrites with formula Cd{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4} (x=0.0, 0.2, 0.35, 0.5), have been synthesized by wet chemical co-precipitation technique. Electrical, morphological and Structural properties of the samples have been studied using DC electrical resistivity and Impedance analyzer, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), respectively. XRD, SEM and AFM have been used to study the structural parameters such as measured density, lattice constant, X-ray density, crystallite size and morphology of the synthesized nano-particles. Debye–Scherrer formula has been used for the estimation of crystallite sizes. The estimated crystallite sizes were to be 15–19±2 nm. Hopping length of octahedral and tetrahedral sites have been calculated using indexed XRD data. The porosity and lattice constant increased as Cd{sup 2+}concentration increases. DC electrical resistivity was performed using two probe technique. The decrease of resistivity with temperature confirms the semiconducting nature of the samples. The dielectric properties variation has been studied at room temperature as a function of frequency. Variation of dielectric properties from 100 Hz to 5 MHz has been explained on the basis of Maxwell and Wagner’s model and hoping of electrons on octahedral sites. To separates the grains boundary and grains of the system Cd{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4} the impedance analysis were performed. - Highlights: • Preparation of homogeneous, spherical and single phase well crystallized cobalt ferrites. • A simple and economical PEG assisted wet chemical co-precipitation method has been used. • Increased in DC electrical resistivity and activation energy. • Decease in dielectric constant used for microwave absorber. • AC conductivity of Cd{sup 2+} substituted Co-ferrites increases.

  12. Improved electrical properties of cadmium substituted cobalt ferrites nano-particles for microwave application

    International Nuclear Information System (INIS)

    Ahmad, Rabia; Hussain Gul, Iftikhar; Zarrar, Muhammad; Anwar, Humaira; Khan Niazi, Muhammad Bilal; Khan, Azim

    2016-01-01

    Cadmium substituted cobalt ferrites with formula Cd x Co 1−x Fe 2 O 4 (x=0.0, 0.2, 0.35, 0.5), have been synthesized by wet chemical co-precipitation technique. Electrical, morphological and Structural properties of the samples have been studied using DC electrical resistivity and Impedance analyzer, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), respectively. XRD, SEM and AFM have been used to study the structural parameters such as measured density, lattice constant, X-ray density, crystallite size and morphology of the synthesized nano-particles. Debye–Scherrer formula has been used for the estimation of crystallite sizes. The estimated crystallite sizes were to be 15–19±2 nm. Hopping length of octahedral and tetrahedral sites have been calculated using indexed XRD data. The porosity and lattice constant increased as Cd 2+ concentration increases. DC electrical resistivity was performed using two probe technique. The decrease of resistivity with temperature confirms the semiconducting nature of the samples. The dielectric properties variation has been studied at room temperature as a function of frequency. Variation of dielectric properties from 100 Hz to 5 MHz has been explained on the basis of Maxwell and Wagner’s model and hoping of electrons on octahedral sites. To separates the grains boundary and grains of the system Cd x Co 1−x Fe 2 O 4 the impedance analysis were performed. - Highlights: • Preparation of homogeneous, spherical and single phase well crystallized cobalt ferrites. • A simple and economical PEG assisted wet chemical co-precipitation method has been used. • Increased in DC electrical resistivity and activation energy. • Decease in dielectric constant used for microwave absorber. • AC conductivity of Cd 2+ substituted Co-ferrites increases.

  13. The effect of α-alumina particles on the properties of EN AC-44200 Al alloy based composite materials

    OpenAIRE

    J.W. Kaczmar; A. Kurzawa

    2012-01-01

    Purpose: The unreinforced EN AC-44200 aluminium alloy is characterized by the medium mechanical properties and the purpose of performed investigations was improvement of mechanical properties of this alloy by introducing stable ceramic α-alumina particles.Design/methodology/approach: The composite materials were manufactured by squeeze casting of porous ceramic preforms characterized by the open porosities of 90%, 80%, 70% and 60% with the liquid EN AC- 44200 aluminum alloy. The composite mat...

  14. Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

    Energy Technology Data Exchange (ETDEWEB)

    Pavithradevi, S. [Assistant Professor, Department of Physics, Park College of Engineering and Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: madurasuri2210@yahoo.com [Prof & Head, Department of Physics, Government College of Technology, Coimbatore (India); Boobalan, T. [Lecturer, Department of Physics, PSG Polytechnic College, Coimbatore (India)

    2017-03-15

    Nanocrystalline copper ferrite CuFe{sub 2}O{sub 4} is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe{sub 2}O{sub 4} is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe{sub 2}O{sub 4} nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm{sup −1} and 4000 cm{sup −1}. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25–34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field. - Highlights: • Complete removal of hematite phase along with ethylene glycol at 1050 °C. • Large decrease in particle sizes noticed along with ethylene glycol. • Ethylene glycol improves purity of the

  15. Measurements and properties of ice particles and carbon dioxide bubbles in aqueous mixture utilizing optical techniques

    Science.gov (United States)

    Diallo, Amadou O.

    Optical techniques are used to determine the size, shape and many other properties of particles ranging from the micro to a nano-level. These techniques have endless applications. This research is based on a project assigned by a "Vendor" that wants anonymity. The Leica optical microscope and the Dark Field Polarizing Metallurgical Microscope is used to determine the size and count of ice crystals (Vendors products) in multiple time frames. Since the ice temperature influences, its symmetry and the shape is subject to changes at room temperature (300 K) and the atmospheric pressure that is exerted on the ice crystals varies. The ice crystals are in a mixture of water, electrolytes and carbon dioxide with the optical spectroscopy (Qpod2) and Spectra suite, the optical density of the ice crystals is established from the absorbance and transmission measurements. The optical density in this case is also referred to as absorption; it is plotted with respect to a frequency (GHz), wavelength (nm) or Raman shift (1/cm) which shows the light colliding with the ice particles and CO2. Depending on the peaks positions, it is possible to profile the ice crystal sizes using a mean distribution plots. The region of absorbency wavelength expected for the ice is in the visible range; the water molecules in the (UV) Ultra-violet range and the CO2 in the (IR) infrared region. It is also possible to obtain the reflection and transmission output as a percentage change with the wavelengths ranging from 200 to 1100 nm. The refractive index of the ice can be correlated to the density based on the optical acoustic theorem, or Mie Scattering Theory. The viscosity of the ice crystals and the solutions from which the ice crystals are made of as well are recorded with the SV-10 viscometer. The baseline viscosity is used as reference and set lower than that of the ice crystals. The Zeta potential of the particles present in the mixture are approximated by first finding the viscosity of the

  16. Effect of in-situ formed Al3Ti particles on the microstructure and mechanical properties of 6061 Al alloy

    Science.gov (United States)

    Gupta, Rahul; Chaudhari, G. P.; Daniel, B. S. S.

    2018-03-01

    In this study, in situ Titanium-tri-aluminide (Al3Ti) particles reinforced Al 6061 alloy matrix composites were fabricated by the reaction of potassium hexafluorotitanate (K2TiF6) inorganic salt with molten Al 6061 alloy via liquid metallurgy route. The development of in-situ Al3Ti particles and their effects on the mechanical properties such as yield strength (YS), ductility, ultimate tensile strength (UTS) and hardness, and microstructure of Al 6061 alloy were studied. It was observed from the results that in-situ formed Al3Ti particles were blocky in morphology whose average size was around 2.6 ± 1.1 μm. Microstructure studies showed that grain size of Al matrix was reduced due to the nucleating effect of Al3Ti particles. It was observed from the mechanical properties analysis that when the volume fraction of Al3Ti particles was increased, the hardness, UTS and YS of the composites were also increased as compared to that of Al 6061 alloy. An improvement in ductility was observed with the dispersion of Al3Ti particles in base alloy which is contrary to many other composites.

  17. Effects of physical properties of powder particles on binder liquid requirement and agglomerate growth mechanisms in a high shear mixer.

    Science.gov (United States)

    Johansen, A; Schaefer, T

    2001-09-01

    A study was performed in order to elucidate the effects of the physical properties of small powder particles on binder liquid requirement and agglomerate growth mechanisms. Three grades of calcium carbonate having different particle size distribution, surface area, and particle shape but approximately the same median particle size (4-5 microm), were melt agglomerated with polyethylene glycol (PEG) 3000 or 20,000 in an 8-l high shear mixer at three impeller speeds. The binder liquid requirement was found to be very dependent on the packing properties of the powder, a denser packing resulting in a lower binder liquid requirement. The densification of the agglomerates in the high shear mixer could be approximately predicted by compressing a powder sample in a compaction simulator. With the PEG having the highest viscosity (PEG 20,000), the agglomerate formation and growth occurred primarily by the immersion mechanism, whereas PEG 3000 gave rise to agglomerate growth by coalescence. Powder particles with a rounded shape and a narrow size distribution resulted in breakage of agglomerates with PEG 3000, whereas no breakage was seen with PEG 20,000. Powder particles having an irregular shape and surface structure could be agglomerated with PEG 20,000, whereas agglomerate growth became uncontrollable with PEG 3000. When PEG 20,000 was added as a powder instead of flakes, the resultant agglomerates became rounder and the size distribution narrower.

  18. Analysis of the hygroscopic and volatile properties of ammonium sulphate seeded and unseeded SOA particles

    Directory of Open Access Journals (Sweden)

    N. K. Meyer

    2009-01-01

    Full Text Available The volatile and hygroscopic properties of ammonium sulphate seeded and unseeded secondary organic aerosol (SOA derived from the photo-oxidation of atmospherically relevant concentrations of α-pinene were studied. The seed particles were electrospray generated ammonium sulphate ((NH42SO4 having diameters of approximately 33 nm with a quasi-mono-disperse size distribution (geometric standard deviation σg=1.3. The volatile and hygroscopic properties of both seeded and unseeded SOA were simultaneously measured with a VH-TDMA (volatility – hygroscopicity tandem differential mobility analyzer. VH-TDMA measurements of unseeded SOA show a decrease in the hygroscopic growth (HGF factor for increased volatilisation temperatures such that the more volatile compounds appear to be more hygroscopic. This is opposite to the expected preferential evaporation of more volatile but less hygroscopic material, but could also be due to enhanced oligomerisation occurring at the higher temperature in the thermodenuder. In addition, HGF measurements of seeded SOA were measured as a function of time at two relative humidities, below (RH 75% and above (RH 85% the deliquescence relative humidity (DRH of the pure ammonium sulphate seeds. As these measurements were conducted during the onset phase of photo-oxidation, during particle growth, they enabled us to find the dependence of the HGF as a function of the volume fraction of the SOA coating. HGF's measured at RH of 85% showed a continuous decrease as the SOA coating thickness increased. The measured growth factors show good agreements with ZSR predictions indicating that, at these RH values, there are only minor solute-solute interactions. At 75% RH, as the SOA fraction increased, a rapid increase in the HGF was observed indicating that an increasing fraction of the (NH42SO4 is subject to a phase transition, going into solution, with an

  19. Analysis of the hygroscopic and volatile properties of ammonium sulphate seeded and unseeded SOA particles

    Science.gov (United States)

    Meyer, N. K.; Duplissy, J.; Gysel, M.; Metzger, A.; Dommen, J.; Weingartner, E.; Alfarra, M. R.; Prevot, A. S. H.; Fletcher, C.; Good, N.; McFiggans, G.; Jonsson, Â. M.; Hallquist, M.; Baltensperger, U.; Ristovski, Z. D.

    2009-01-01

    The volatile and hygroscopic properties of ammonium sulphate seeded and unseeded secondary organic aerosol (SOA) derived from the photo-oxidation of atmospherically relevant concentrations of α-pinene were studied. The seed particles were electrospray generated ammonium sulphate ((NH4)2SO4) having diameters of approximately 33 nm with a quasi-mono-disperse size distribution (geometric standard deviation σg=1.3). The volatile and hygroscopic properties of both seeded and unseeded SOA were simultaneously measured with a VH-TDMA (volatility - hygroscopicity tandem differential mobility analyzer). VH-TDMA measurements of unseeded SOA show a decrease in the hygroscopic growth (HGF) factor for increased volatilisation temperatures such that the more volatile compounds appear to be more hygroscopic. This is opposite to the expected preferential evaporation of more volatile but less hygroscopic material, but could also be due to enhanced oligomerisation occurring at the higher temperature in the thermodenuder. In addition, HGF measurements of seeded SOA were measured as a function of time at two relative humidities, below (RH 75%) and above (RH 85%) the deliquescence relative humidity (DRH) of the pure ammonium sulphate seeds. As these measurements were conducted during the onset phase of photo-oxidation, during particle growth, they enabled us to find the dependence of the HGF as a function of the volume fraction of the SOA coating. HGF's measured at RH of 85% showed a continuous decrease as the SOA coating thickness increased. The measured growth factors show good agreements with ZSR predictions indicating that, at these RH values, there are only minor solute-solute interactions. At 75% RH, as the SOA fraction increased, a rapid increase in the HGF was observed indicating that an increasing fraction of the (NH4)2SO4 is subject to a phase transition, going into solution, with an increasing volume fraction of SOA. To our knowledge this is the first time that SOA derived

  20. Physico-chemical properties and biological effects of diesel and biomass particles

    KAUST Repository

    Longhin, Eleonora; Gualtieri, Maurizio; Capasso, Laura; Bengalli, Rossella; Mollerup, Steen; Holme, Jø rn A.; Ø vrevik, Johan; Casadei, Simone; Di Benedetto, Cristiano; Parenti, Paolo; Camatini, Marina

    2016-01-01

    © 2016 Elsevier Ltd. Diesel combustion and solid biomass burning are the major sources of ultrafine particles (UFP) in urbanized areas. Cardiovascular and pulmonary diseases, including lung cancer, are possible outcomes of combustion particles

  1. Effects of liquid morphology and distribution on the apparent properties of porous media made of stacked particles

    Directory of Open Access Journals (Sweden)

    Mingzhi Yu

    2015-05-01

    Full Text Available To understand the effects of liquid morphology on the apparent transfer properties of porous media formed by stacked particles, the authors investigate the particles’ aggregation state, apparent volume, thermal conductivity, and electrical conductivity of wet stacked glass beads. It shows that the liquid mainly exists as liquid bridges when the liquid content is low and connects each other when high. The transformation of liquid morphology and distribution influences the liquid effects on particles, thus changing the aggregation state of the particles and the apparent properties of the porous media in turn. A model is developed for predicting the critical liquid content at which the liquid morphology shifts from the state of liquid bridges into the state of interconnectedness. The prediction from the model is in good agreement with the experiment.

  2. Life cycle impact assessment modeling for particulate matter: A new approach based on physico-chemical particle properties.

    Science.gov (United States)

    Notter, Dominic A

    2015-09-01

    Particulate matter (PM) causes severe damage to human health globally. Airborne PM is a mixture of solid and liquid droplets suspended in air. It consists of organic and inorganic components, and the particles of concern range in size from a few nanometers to approximately 10μm. The complexity of PM is considered to be the reason for the poor understanding of PM and may also be the reason why PM in environmental impact assessment is poorly defined. Currently, life cycle impact assessment is unable to differentiate highly toxic soot particles from relatively harmless sea salt. The aim of this article is to present a new impact assessment for PM where the impact of PM is modeled based on particle physico-chemical properties. With the new method, 2781 characterization factors that account for particle mass, particle number concentration, particle size, chemical composition and solubility were calculated. Because particle sizes vary over four orders of magnitudes, a sound assessment of PM requires that the exposure model includes deposition of particles in the lungs and that the fate model includes coagulation as a removal mechanism for ultrafine particles. The effects model combines effects from particle size, solubility and chemical composition. The first results from case studies suggest that PM that stems from emissions generally assumed to be highly toxic (e.g. biomass combustion and fossil fuel combustion) might lead to results that are similar compared with an assessment of PM using established methods. However, if harmless PM emissions are emitted, established methods enormously overestimate the damage. The new impact assessment allows a high resolution of the damage allocatable to different size fractions or chemical components. This feature supports a more efficient optimization of processes and products when combating air pollution. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. The influence of particle size distribution on the properties of metal-injection-moulded 17-4 PH stainless steel

    CSIR Research Space (South Africa)

    Seerane, Mandy

    2016-10-01

    Full Text Available Metal injection moulding (MIM) is a near-net-shaping powder metallurgy technique suitable for the cost-effective mass production of small and complex components. In this paper, the effects of the metal powder particle size on the final properties...

  4. The influence of particle size distribution on the properties of metalinjection-moulded 17-4 PH stainless steel

    CSIR Research Space (South Africa)

    Seerane, Mandy

    2016-10-01

    Full Text Available Metal injection moulding (MIM) is a near-net-shaping powder metallurgy technique suitable for the cost-effective mass production of small and complex components. In this paper, the effects of the metal powder particle size on the final properties...

  5. 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.

  6. Synthesis and electrochemistry properties of Sn-Sb ultrafine particles as anode of lithium-ion batteries

    International Nuclear Information System (INIS)

    Wang, Zhong; Tian, Wenhuai; Li, Xingguo

    2007-01-01

    Ultrafine particles of Sn-Sb alloys with different chemical composition have been prepared by hydrogen plasma-metal reaction. Structure, morphology, size and chemical composition of the Sn-Sb ultrafine particles were investigated by transmission electron microscopy, X-ray diffraction, BET gas adsorption, and induction-coupled plasma spectroscopy. It was found that all the particles have spherical shapes, with average particle size in the range of 100-300 nm. The electrochemistry properties as an alternative anode material for lithium-ion batteries have been characterized by constant current cycling and cyclic voltammetry. Electrochemical measurements showed that the alloys with Sn-46.5 at.% Sb have best reversible capacity and capacity retention. It exhibited a high reversible lithium-ion storage capacity of 701 mAh g -1 in the initial cycle, which has remained at 81% (i.e., 566 mAh g -1 ) of its original capacity after 20 cycles

  7. Particle formation induced by sonication during yogurt fermentation - Impact of exopolysaccharide-producing starter cultures on physical properties.

    Science.gov (United States)

    Körzendörfer, Adrian; Nöbel, Stefan; Hinrichs, Jörg

    2017-07-01

    Two major quality defects of yogurt are syneresis and the presence of large particles, and several reasons have been extensively discussed. Vibrations during fermentation, particularly generated by pumps, must be considered as a further cause as latest research showed that both ultrasound and low frequencies induced visible particles. The aim of this study was to investigate the impact of sonication during fermentation with starter cultures differing in exopolysaccharide (EPS) synthesis on the physical properties of set (syneresis, firmness) and stirred yogurt (large particles, laser diffraction, rheology). Skim milk was fermented with starter cultures YC-471 (low EPS) or YF-L 901 (high EPS) (Chr. Hansen) and sonicated for 5min at pH5.2. Sonicated set gels exhibited syneresis and were softer than respective controls. The mechanical treatment was adjusted to quantify visible particles (d≥0.9mm) in stirred yogurts properly. Sonication significantly increased particle numbers, however, the effect was less pronounced when YF-L 901 was used, indicating EPS as a tool to reduce syneresis and particle formation due to vibrations. Rheological parameters and size of microgel particles were rather influenced by starter cultures than by sonication. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Effectiveness of amorphous silica encapsulation technology on welding fume particles and its impact on mechanical properties of welds

    International Nuclear Information System (INIS)

    Wang, Jun; Wu, Chang-Yu; Franke, Gene

    2014-01-01

    Highlights: • A novel welding shielding gas containing a silica precursor. • Up to 76% of the welding fume particles encapsulated in an amorphous silica layer. • No statistical difference between different types of welds in mechanical tests. • Can potentially reduce the toxicity of welding fume particles. - Abstract: Stainless steel welding generates nano-sized fume particles containing toxic metals which may cause serious health effects upon inhalation. The objective of this study was to investigate the effectiveness of an amorphous silica encapsulation (ASE) technology by evaluating its silica coating efficiency (SCE), particle morphology, and its impact on the weld’s mechanical properties. Tetramethylsilane (TMS) added to the welding shielding gas decomposed at the high-temperature arc zone to enable the silica coating. Collected welding fume particles were digested by two acid mixtures with different degrees of silica solubility, and the measured mass differences in the digests were used to determine the SCE. The SCEs were around 48–64% at the low and medium primary shielding gas flow rates. The highest SCE of 76% occurred at the high shielding gas flow rate (30 Lpm) with a TMS carrier gas flow of 0.64 Lpm. Transmission electron microscopy (TEM) images confirmed the amorphous silica layer on the welding fume particles at most gas flow rates, as well as abundant stand-alone silica particles formed at the high gas flow rate. Metallography showed that welds from the baseline and from the ASE technology were similar except for a tiny crack found in one particular weld made with the ASE technology. Tensile tests showed no statistical difference between the baseline and the ASE welds. All the above test results confirm that welding equipment retrofitted with the ASE technology has the potential to effectively address the toxicity problem of welding fume particles without affecting the mechanical properties of the welds

  9. Study of SUSY particles properties at the future International Linear Collider with the International Large Detector

    International Nuclear Information System (INIS)

    Wichmann, K.

    2009-01-01

    Recently, Letters of Intent (LoI) for experiments at the International Linear Collider (ILC) have been submitted. Among the three proposals is the International Large Detector (ILD) concept which is at the focus of these studies. From various subjects addressed in the LoI, a wide spectrum of studies of SUSY particle properties is presented here. Most of them are benchmark reactions for the ILC and can be used both in physics studies and in work on detector design and optimization, respectively. All studies were performed with a full detector simulation using GEANT4, which is a great improvement compared to the previous results with much less detailed, so called f ast , simulation (SIMDET). The importance of this improved simulation is reflected in the results. The presented analyzes have been chosen to be the most challenging for the detector to study its performance and guide the detector development. Additionally an important problem of unavoidable beam induced backgrounds at linear colliders is addressed and ways of reducing its impact on physics studies are shown for an example SUSY analysis. (author)

  10. Measurement of fragmentation properties of charmed particle production in charged-current neutrino interactions

    CERN Document Server

    Onengüt, G; De Jong, M; Konijn, J; Melzer, O; Oldeman, R G C; Pesen, E; Van der Poel, C A F J; Visschers, J L; Güler, M; Köse, U; Serin-Zeyrek, M; Kama, S; Sever, R; Tolun,, P; Zeyrek, M T; Catanesi, M G; De Serio, M; Ieva, M; Muciaccia, M T; Radicioni, E; Simone, S; Bülte, A; Winter, Klaus; Van de Vyver, B; Vilain, P; Wilquet, G; Saitta, B; Di Capua, E; Ogawa, S; Shibuya, H; Artamonov, A V; Brunner, J; Chizhov, M; Cussans, D G; Doucet, M; Fabre, Jean-Paul; Hristova, I R; Kawamura, T; Kolev, D; Litmaath, M; Meinhard, H; Panman, J; Papadopoulos, I M; Ricciardi, S; Rozanov, A; Saltzberg, D; Tsenov, R V; Uiterwijk, J W E; Zucchelli, P; Goldberg, J; Chikawa, M; Arik, E; Song, J S; Yoon, C S; Kodama, K; Ushida, N; Aoki, S; Hara, T; Delbar, T; Favart, D; Grégoire, G; Kalinin, S; Makhlyoueva, I V; Gorbunov, P; Khovanskii, V D; Shamanov, V V; Tsukerman, I; Bruski, N; Frekers, D; Rondeshagen, D; Wolff, T; Hoshino, K; Kawada, J; Komatsu, M; Miyanishi, M; Nakamura, M; Nakano, T; Narita, K; Niu, K; Niwa, K; Nonaka, N; Sato, O; Toshito, T; Buontempo, S; Cocco, A G; D'Ambrosio, N; De Lellis, G; De Rosa, G; Di Capua, F; Ereditato, A; Fiorillo, G; Marotta, A; Messina, M; Migliozzi, P; Pistillo, C; Santorelli, R; Scotto-Lavina, L; Strolin, P; Tioukov, V; Nakamura, K; Okusawa, T; Dore, U; FLoverre, P; Ludovici, L; Maslennikov, A L; Righini, P; Rosa, G; Santacesaria, R; Satta, A; Spada, F R; Barbuto, E; Bozza, C; Grella, G; Romano, G; Sirignano, C; Sorrentino, S; Sato, Y; Tezuka, I

    2004-01-01

    During the years 1994-97, the emulsion target of the CHORUS detector was exposed to the wideband neutrino beam of the CERN SPS. In total about 100 000 charged-current neutrino interactions were located in the nuclear emulsion target and fully reconstructed. From this sample of events which was based on the data acquired by new automatic scanning systems, 1048 D0 events were selected by a pattern recognition program. They were confirmed as neutral-particle decays through visual inspection. Fragmentation properties of deep-inelastic charm production were measured using these events. Distributions of the D0 momentum, Feynman x(x_F), z and tan thetaôut, the transverse angle out of the leptonic plane defined by the muon and the neutrino, are presented. The mean value of z was measured to be (z) = 0.63 +- 0.03(stat) +- 0.01(syst). From fits to the z distribution, values for the Peterson parameter epsilon_p = 0.108 +- 0.017(stat) +- 0.013(syst) and the Collins-Spiller parameter epsilon_CS = 0.21^+0.05_-0.04(stat) +...

  11. Performances and nitrification properties of biological aerated filters with zeolite, ceramic particle and carbonate media.

    Science.gov (United States)

    Qiu, Liping; Zhang, Shoubin; Wang, Guangwei; Du, Mao'an

    2010-10-01

    The performance and nitrification properties of three BAFs, with ceramic, zeolite and carbonate media, respectively, were investigated to evaluate the feasibility of employing these materials as biological aerated filter media. All three BAFs shown a promising COD and SS removal performance, while influent pH was 6.5-8.1, air-liquid ratio was 5:1 and HRT was 1.25-2.5 h, respectively. Ammonia removal in BAFs was inhibited when organic and ammonia nitrogen loading were increased, but promoted effectively with the increase pH value. Zeolite and carbonate were more suitable for nitrification than ceramic particle when influent pH below 6.5. It is feasible to employ these media in BAF and adequate bed volume has to be supplied to satisfy the requirement of removal COD, SS and ammonia nitrogen simultaneously in a biofilter. The carbonate with a strong buffer capacity is more suitable to treat the wastewater with variable or lower pH. Copyright 2010 Elsevier Ltd. All rights reserved.

  12. Effect of Recycled Rubber Particles and Silica on Tensile and Tear Properties of Natural Rubber Composites

    Directory of Open Access Journals (Sweden)

    Velu CHANDRAN

    2016-05-01

    Full Text Available Application of scrap rubber and worn out tires in natural rubber compounds has been studied. The scrap rubber can, however, be recycled and compounded with natural rubber and thus can be generated as a rubber composite. In this work, recycled rubber particles (RRP were prepared using pulverization process. Then, RRP was blended with natural rubber and silica compounds, and it was synthesized by two- roll mill and hydraulic press at specified operating conditions. The samples ranging from 0 to 40 phr of RRP loaded with silica were used as constant filler. The mechanical properties and morphological analysis were carried out. The results showed that tensile strength and elongation at break gradually decreased with increasing RRP loading in natural rubber and silica compounds. Tensile modulus went down at 10 phr of RRP and then showed an increasing trend. Hardness increased up to 30 phr of RRP and tear strength increased up to 20 phr of RRP. A comparative study was also carried out with virgin natural rubber vulcanizates. The incorporation of RRP and silica up to 20 phr in natural rubber did not lower the performance of rubber articles. Morphological studies revealed that better filler dispersion, interfacial adhesion, and cross link density could increase the tensile and tear strengths.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.7330

  13. Thermoplastic starch composites with TiO2 particles: Preparation, morphology, rheology and mechanical properties.

    Science.gov (United States)

    Ostafińska, A; Mikešová, J; Krejčíková, S; Nevoralová, M; Šturcová, A; Zhigunov, A; Michálková, D; Šlouf, M

    2017-08-01

    Composites of thermoplastic starch (TPS) with titanium dioxide particles (mTiO 2 ; average size 0.1μm) with very homogeneous matrix and well-dispersed filler were prepared by a two-step method, including solution casting (SC) followed by melt mixing (MM). Light and scanning electron microscopy confirmed that only the two-step procedure (SC+MM) resulted in ideally homogeneous TPS/mTiO 2 systems. The composites prepared by single-step MM contained non-plasticized starch granules and the composites prepared by single-step SC suffered from mTiO 2 agglomeration. Dynamic mechanical measurements showed an increase modulus with increasing filler concentration. In TPS containing 3wt.% of mTiO 2 the stiffness was enhanced by >40%. Further experiments revealed that the recommended addition of chitosan or the exchange of mTiO 2 for anisometric titanate nanotubes with high aspect ratio did not improve the properties of the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Dependence of equilibrium properties of channeled particles on transverse quasi temperature

    International Nuclear Information System (INIS)

    Kashlev, Yu.A.

    2006-01-01

    Quasi-equilibrium and kinetic characteristics of channeled particles are investigated by methods of nonequilibrium statistical thermodynamics. The equilibrium equation of the transverse energy of fast particles and the equilibrium equation of the transverse momentum of particles are derived. It is shown that equilibrium equations solution permits to obtain the expression for the transverse quasi-temperature of the channeled particle subsystem. The quasi-equilibrium angular distribution of particles after transmission through a thin monocrystal and the angular distribution at backscattering are studied. The evaluated data of the transverse quasi-temperature are presented for the case of iodine ion channeling through silver crystals [ru

  15. Chemical and Physical Properties of Individual Aerosol Particles Characterized in Sacramento, CA during CARES Field Campaign

    Science.gov (United States)

    Zelenyuk, A.; Beranek, J.; Vaden, T.; Imre, D. G.; Zaveri, R. A.

    2011-12-01

    We present results of measurements conducted by our Single Particle Mass Spectrometer, SPLAT II, in Sacramento, CA over the month of June 2010. SPLAT II measured the size of 195 million particles, and compositions of 10 million particles. In addition to size and composition, SPLAT II simultaneously measured size, density and composition of 121,000 individual particles. These measurements were conducted 2 - 3 times per day, depending on conditions. The data show that throughout the day particles were relatively small (<200 nm), and the vast majority were composed of oxygenated organics mixed with various amounts of sulfate. In addition, we characterized fresh and processed soot, biomass burning aerosol, organic amines, fresh and processed sea salt, and few dust particles. The data show a reproducible diurnal pattern in aerosol size distributions, number concentrations, and compositions. Early in the day, number concentrations were low, particles were very small, and the size distributions peaked at ~70 nm. At this time of the day, 80 nm particles had a density of 1.3 g cm-3; while the density of 200 nm particles was 1.6 g cm-3, consistent with our mass spectra showing that smaller particles were composed of organics mixed with ~10% sulfates, while larger particles were composed mostly of sulfate mixed with a small amount of organics. Later in the day, secondary organic aerosols (SOA) formation led to a number of nucleation events that significantly increased the number concentrations of very small particles. By mid-afternoon, as more SOA formed and condensed, particles increased in size the number concentrations of particles larger than 70 nm increased and the densities of particles 80 to 200 nm particles was ~1.3 g cm-3. The vast majority of these particles were composed of oxygenated organics mixed with a ~10% sulfate. In other words they were SOA particles mixed with a small amount of sulfate. The mass spectra of these particles shows that there were two types of

  16. Study of relationships between microstructures and service properties, of U(Mo) fissile alloys particles

    International Nuclear Information System (INIS)

    Champion, G.

    2013-01-01

    This thesis enters in the Material and Testing Reactors (MTRs) framework where the necessity to use a Low- Enriched Uranium (LEU) fuel has led to the development of a dense fissile material based on U(Mo) alloys. The designed fuel is a composite material, made of dispersed U(Mo) particles embedded in an Al based matrix. Post- Irradiation Examinations of these LEU fuel plates showed that the irradiation behaviour of the fuel is not fit for purpose yet. This is mainly due to the growth of an interaction layer between the fuel and the matrix and to the bad gas retention efficiency of the fuel particles. This thesis had for purpose the development of several solutions in order to modify and/or decrease or even inhibit the fuel/matrix interaction and to increase the gas retention capacities of the fuel. In order to achieve so, two solutions have been tested during this thesis, (i) optimization of the U(Mo) alloy intrinsic microstructural properties and (ii) modification of the fuel meat/matrix interface, through the deposition of a layer acting as a 'diffusion barrier'. Concerning the first axis of study, a characterization campaign of the reference powders has been performed, as a first step, in order to identify the key parameters for the development of products showing an 'optimized' microstructure. Two novel products have then been developed: one based on a combined process associating 'atomization + grinding' and another, which consists in a magnesiothermy process. These products were subjected to characterization: X-Ray and neutron diffraction, electron backscattered diffraction and transmission electron microscopy have been performed in particular. We managed to show that these powders can be an advantage concerning the issue with the gas retention capacities of the fuel. Concerning the growth of the interaction layer, a third product has been developed: an U(Mo) atomized powder, coated with an alumina layer. We managed to show that a thickness between 100 and

  17. Micrometer-sized Water Ice Particles for Planetary Science Experiments: Influence of Surface Structure on Collisional Properties

    Science.gov (United States)

    Gaertner, Sabrina; Gundlach, Bastian; Headen, Thomas F.; Ratte, Judy; Oesert, Joachim; Gorb, Stanislav N.; Youngs, Tristan G. A.; Bowron, Daniel T.; Blum, Jürgen; Fraser, Helen

    2018-06-01

    Models and observations suggest that particle aggregation at and beyond the snowline is aided by water ice. As icy particles play such a crucial role in the earliest stages of planet formation, many laboratory studies have exploited their collisional properties across a wide range of parameters (particle size, impact velocity, temperature T, and pressure P).However, not all of these parameters have always been varied systematically, leading to apparently contradictory results on collision outcomes. Previous experiments only agreed that a temperature dependence set in above ≈210 K. Open questions remain as to what extent the structural properties of the particles themselves dictate collision outcomes. The P–T gradients in protoplanetary disks mean that the ices are constantly processed, undergoing phase changes between different solid phases and the gas phase. To understand how effectively collision experiments reproduce protoplanetary disk conditions, environmental impacts on particle structure need to be investigated.We characterized the bulk and surface structure of icy particles used in collision experiments, exploiting the unique capabilities of the NIMROD neutron scattering instrument. Varying temperature at a constant pressure of around 30 mbar, we studied structural alterations to determine which of the observed properties matches the temperature dependencies observed in collisional behaviour.Our icy grains are formed under liquid nitrogen and heated from 103 to 247 K. As a result, they undergo changes in the crystalline ice-phase, sublimation, sintering and surface pre-melting. An increase in the thickness of the diffuse surface layer from ≈10 to ≈30 Å (≈2.5 to 12 bilayers) suggests increased molecular mobility at temperatures above ≈210 K.Because none of the other changes ties in with the temperature trends in collisional outcomes, we conclude that the diffuse interface plays a key role in collision experiments at these temperatures

  18. Optical properties of non-spherical desert dust particles in the terrestrial infrared – An asymptotic approximation approach

    International Nuclear Information System (INIS)

    Klüser, Lars; Di Biagio, Claudia; Kleiber, Paul D.; Formenti, Paola; Grassian, Vicki H.

    2016-01-01

    Optical properties (extinction efficiency, single scattering albedo, asymmetry parameter and scattering phase function) of five different desert dust minerals have been calculated with an asymptotic approximation approach (AAA) for non-spherical particles. The AAA method combines Rayleigh-limit approximations with an asymptotic geometric optics solution in a simple and straightforward formulation. The simulated extinction spectra have been compared with classical Lorenz–Mie calculations as well as with laboratory measurements of dust extinction. This comparison has been done for single minerals and with bulk dust samples collected from desert environments. It is shown that the non-spherical asymptotic approximation improves the spectral extinction pattern, including position of the extinction peaks, compared to the Lorenz–Mie calculations for spherical particles. Squared correlation coefficients from the asymptotic approach range from 0.84 to 0.96 for the mineral components whereas the corresponding numbers for Lorenz–Mie simulations range from 0.54 to 0.85. Moreover the blue shift typically found in Lorenz–Mie results is not present in the AAA simulations. The comparison of spectra simulated with the AAA for different shape assumptions suggests that the differences mainly stem from the assumption of the particle shape and not from the formulation of the method itself. It has been shown that the choice of particle shape strongly impacts the quality of the simulations. Additionally, the comparison of simulated extinction spectra with bulk dust measurements indicates that within airborne dust the composition may be inhomogeneous over the range of dust particle sizes, making the calculation of reliable radiative properties of desert dust even more complex. - Highlights: • A fast and simple method for estimating optical properties of dust. • Can be used with non-spherical particles of arbitrary size distributions. • Comparison with Mie simulations and

  19. Controlling the radiative properties of cool black-color coatings pigmented with CuO submicron particles

    International Nuclear Information System (INIS)

    Gonome, Hiroki; Baneshi, Mehdi; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao

    2014-01-01

    The objective of this study was to design a pigmented coating with dark appearance that maintains a low temperature while exposed to sunlight. The radiative properties of a black-color coating pigmented with copper oxide (CuO) submicron particles are described. In the present work, the spectral behavior of the CuO-pigmented coating was calculated. The radiative properties of CuO particles were evaluated, and the radiative transfer in the pigmented coating was modeled using the radiation element method by ray emission model (REM 2 ). The coating is made using optimized particles. The reflectivity is measured by spectroscopy and an integrating sphere in the visible (VIS) and near infrared (NIR) regions. By using CuO particles controlled in size, we were able to design a black-color coating with high reflectance in the NIR region. The coating substrate also plays an important role in controlling the reflectance. The NIR reflectance of the coating on a standard white substrate with appropriate coating thickness and volume fraction was much higher than that on a standard black substrate. From the comparison between the experimental and calculated results, we know that more accurate particle size control enables us to achieve better performance. The use of appropriate particles with optimum size, coating thickness and volume fraction on a suitable substrate enables cool and black-color coating against solar irradiation. -- Highlights: • A new approach in designing pigmented coatings was used. • The effects of particles size on both visible and near infrared reflectivities were studied. • The results of numerical calculation were compared with experimental ones for CuO powders

  20. Precipitation of amorphous SiO2 particles and their properties

    Directory of Open Access Journals (Sweden)

    S. Musić

    2011-03-01

    Full Text Available The experimental conditions were optimized for the synthesis of amorphous SiO2 particles by the reaction of neutralization of sodium silicate solution with H2SO4 solution. Amorphous SiO2 particles were characterized by XRD, FT-IR, FE-SEM, EDS and microelectrophoresis. The amorphous peak was located at 2θ = 21.8º in the XRD pattern. Primary SiO2 particles were ~ 15 to ~ 30 nm in size and they aggregated into bigger particles. Amorphous SiO2 particles showed a specific surface area up to 130 m²g-1, dependent on the parameters of the precipitation process. The EDS spectrum of amorphous SiO2 particles did not show contamination with sulfate or other ions, which cannot be excluded in traces. pHzpc =1.7 was obtained by microelectrophoresis.

  1. A comparison of solar energetic particle event timescales with properties of associated coronal mass ejections

    International Nuclear Information System (INIS)

    Kahler, S. W.

    2013-01-01

    The dependence of solar energetic proton (SEP) event peak intensities Ip on properties of associated coronal mass ejections (CMEs) has been extensively examined, but the dependence of SEP event timescales is not well known. We define three timescales of 20 MeV SEP events and ask how they are related to speeds v CME or widths W of their associated CMEs observed by LASCO/SOHO. The timescales of the EPACT/Wind 20 MeV events are TO, the onset time from CME launch to SEP onset; TR, the rise time from onset to half the peak intensity (0.5Ip); and TD, the duration of the SEP intensity above 0.5Ip. This is a statistical study based on 217 SEP-CME events observed during 1996-2008. The large number of SEP events allows us to examine the SEP-CME relationship in five solar-source longitude ranges. In general, we statistically find that TO declines slightly with v CME , and TR and TD increase with both v CME and W. TO is inversely correlated with log Ip, as expected from a particle background effect. We discuss the implications of this result and find that a background-independent parameter TO+TR also increases with v CME and W. The correlations generally fall below the 98% significance level, but there is a significant correlation between v CME and W which renders interpretation of the timescale results uncertain. We suggest that faster (and wider) CMEs drive shocks and accelerate SEPs over longer times to produce the longer TR and TD SEP timescales.

  2. Effects of baking conditions, dough fermentation, and bran particle size on antioxidant properties of whole-wheat pizza crusts.

    Science.gov (United States)

    Moore, Jeffrey; Luther, Marla; Cheng, Zhihong; Yu, Liangli Lucy

    2009-02-11

    This study investigated the effects of processing conditions including bran particle size, dough fermentation time, and baking time and temperature on the extractable antioxidant properties of whole-wheat pizza crust. Experiments were carried out using two different varieties of hard white winter wheat, Trego and Lakin. Antioxidant properties examined included oxygen radical absorbing capacity (ORAC), hydroxyl radical scavenging capacity (HOSC), relative 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity (RDSC), cation 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging capacity, total phenolic contents (TPC), and ferulic acid contents. Results indicated that bran particle size had no effect on the antioxidant properties evaluated. Increasing dough fermentation time from 0 to 48 h had no significant influence on antioxidant properties except HOSC, which increased as much as 28%, possibly as a result of increase in soluble free ferulic acid, which increased as much as 130%. Increasing baking temperature from 204 to 288 degrees C with a 7 min bake time increased all evaluated antioxidant properties by as much as 82%. Increasing baking time from 7 to 14 min with 204 degrees C baking temperature might increase some antioxidant properties as much as 60%. The results from this study suggest that longer dough fermentation times and increased baking time or temperature may be potential approaches to increase the antioxidant availability in whole-wheat pizza crust.

  3. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    Science.gov (United States)

    Petzold, A.; Hasselbach, J.; Lauer, P.; Baumann, R.; Franke, K.; Gurk, C.; Schlager, H.; Weingartner, E.

    2008-05-01

    Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel)-1 by number for non-volatile particles and 174±43 mg (kg fuel)-1 by mass for Black Carbon (BC). Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dp<0.3 μm, showing a bi-modal structure. The combustion particle mode is centred at modal diameters of 0.05 μm for raw emissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

  4. The effect of gas-phase polycyclic aromatic hydrocarbons on the formation and properties of biogenic secondary organic aerosol particles

    Energy Technology Data Exchange (ETDEWEB)

    Zelenyuk, Alla [Pacific Northwest National Laboratory; USA; Imre, Dan G. [Imre Consulting; USA; Wilson, Jacqueline [Pacific Northwest National Laboratory; USA; Bell, David M. [Pacific Northwest National Laboratory; USA; Suski, Kaitlyn J. [Pacific Northwest National Laboratory; USA; Shrivastava, Manish [Pacific Northwest National Laboratory; USA; Beránek, Josef [Pacific Northwest National Laboratory; USA; Alexander, M. Lizabeth [Pacific Northwest National Laboratory; USA; Kramer, Amber L. [Department of Chemistry; Oregon State University; USA; Massey Simonich, Staci L. [Department of Chemistry; Oregon State University; USA; Environmental and Molecular Toxicology; Oregon State University

    2017-01-01

    When secondary organic aerosol (SOA) particles are formed by ozonolysis in the presence of gas-phase polycyclic aromatic hydrocarbons (PAHs), their formation and properties are significantly different from SOA particles formed without PAHs. For all SOA precursors and all PAHs, discussed in this study, the presence of the gas-phase PAHs during SOA formation significantly affects particle mass loadings, composition, growth, evaporation kinetics, and viscosity. SOA particles formed in the presence of PAHs have, as part of their compositions, trapped unreacted PAHs and products of heterogeneous reactions between PAHs and ozone. Compared to ‘pure’ SOA particles, these particles exhibit slower evaporation kinetics, have higher fractions of non-volatile components, like oligomers, and higher viscosities, assuring their longer atmospheric lifetimes. In turn, the increased viscosity and decreased volatility provide a shield that protects PAHs from chemical degradation and evaporation, allowing for the long-range transport of these toxic pollutants. The magnitude of the effect of PAHs on SOA formation is surprisingly large. The presence of PAHs during SOA formation increases mass loadings by factors of two to five, and particle number concentrations, in some cases, by more than a factor of 100. Increases in SOA mass, particle number concentrations, and lifetime have important implications to many atmospheric processes related to climate, weather, visibility, and human health, all of which relate to the interactions between biogenic SOA and anthropogenic PAHs. The synergistic relationship between SOA and PAHs presented here are clearly complex and call for future research to elucidate further the underlying processes and their exact atmospheric implications.

  5. Fractal aggregation in relation to formation and properties of particle gels

    NARCIS (Netherlands)

    Bremer, L.G.B.

    1992-01-01

    The purpose of this study is to gain insight into the conditions determining whether small particles in a liquid are able to jointly occupy the total volume thus forming a gel network. In order to build a network the colloidal particles have to be 'sticky', unstable. In the unassociated

  6. Magnetic properties of magnetic liquids with iron-oxide particles - the influence of anisotropy and interactions

    DEFF Research Database (Denmark)

    Johansson, C.; Hanson, M.; Pedersen, Michael Stanley

    1997-01-01

    Magnetic liquids containing iron-oxide particles were investigated by magnetization and Mossbauer measurements. The particles were shown to be maghemite with a spontanious saturation magentization Ms = 320 kA m-1 at 200 K and a normalized high-field susceptibility x/M0 = 5.1x10-6 mkA-1, practically...... independent of temperature. Ms increases with decreasing temperature according to an effective Bloch law with an exponent larger than 1.5, as expected for fine magnetic particles. The model of magnetic particles with uniaxial anisotropy and the actual size distribution gives a consistent description...... of independent measurements of the temperature dependence of the hyperfine field and the isothermal magnetization versus field. From this an effective anisotropy constant of about 4.5x10 4 J m-3 is estimated for a particle with diameter 7.5 nm. The magnetic relaxation, as observed in zero...

  7. Structural and fluorescence properties of Ni:MgO-SiO2 particles synthesized by flame spray pyrolysis

    International Nuclear Information System (INIS)

    Suzuki, Takenobu; Ohishi, Yasutake; Tani, Takao

    2006-01-01

    Structural and fluorescence properties of flame spray-synthesized Ni 1 mol%-doped MgO-SiO 2 nano-particles (MgO:SiO 2 = 100:0, 50:50, 25:75 and 0:100 in mol%) were investigated as a first step to prepare transparent materials containing Ni:MgO for optical gain media. Polyhedral aggregates of primary particles with diameters of 8-19 nm were obtained for all compositions. The 100MgO particles were single crystalline and showed the fluorescences (centered at 1260 and 1320 nm) and lifetime (3.8 ms) similar to those of solid state-synthesized Ni:MgO polycrystalline powder under laser excitation at 976 nm, suggesting Ni ions incorporated in MgO

  8. Effect of suspension characteristics on in-flight particle properties and coating microstructures achieved by suspension plasma spray

    Science.gov (United States)

    Aubignat, E.; Planche, M. P.; Allimant, A.; Billières, D.; Girardot, L.; Bailly, Y.; Montavon, G.

    2014-11-01

    This paper focuses on the influence of suspension properties on the manufacturing of coatings by suspension plasma spraying (SPS). For this purpose, alumina suspensions were formulated with two different liquid phases: water and ethanol. Suspensions were atomized with a twin-fluid nozzle and injected in an atmospheric plasma jet. Suspension injection was optimized thanks to shadowgraphy observations and drop size distribution measurements performed by laser diffraction. In-flight particle velocities were evaluated by particle image velocimetry. In addition, splats were collected on glass substrates, with the same conditions as the ones used during the spray process. Scanning electron microscopy (SEM) and profilometry analyses were then performed to observe the splat morphology and thus to get information on plasma / suspension interactions, such as particle agglomeration. Finally, coatings were manufactured, characterized by SEM and compared to each other.

  9. Particle size distribution and property of bacteria attached to carbon fines in drinking water treatment

    Directory of Open Access Journals (Sweden)

    Wang Leilei

    2008-06-01

    Full Text Available The quantitative change and size distribution of particles in the effluents from a sand filter and a granular activated carbon (GAC filter in a drinking water treatment plant were investigated. The average total concentration of particles in the sand filter effluent during a filter cycle was 148 particles/mL, 27 of which were larger than 2 µm in size. The concentration in the GAC effluent (561 particles/mL was significantly greater than that in the sand filter effluent. The concentration of particles larger than 2 µm in the GAC filter effluent reached 201 particles/mL, with the amount of particles with sizes between 2 µm and 15 µm increasing. The most probable number (MPN of carbon fines reached 43 unit/L after six hours and fines between 0.45 µm and 8.0 µm accounted for more than 50%. The total concentration of outflowing bacteria in the GAC filter effluent, 350 CFU (colony-forming units/mL, was greater than that in the sand filter effluent, 210 CFU/mL. The desorbed bacteria concentration reached an average of 310 CFU/mg fines. The disinfection efficiency of desorbed bacteria was lower than 40% with 1.5 mg/L of chlorine. The disinfection effect showed that the inactivation rate with 2.0 mg/L of chloramine (90% was higher than that with chlorine (70%. Experimental results indicated that the high particle concentration in raw water and sedimentation effluent led to high levels of outflowing particles in the sand filter effluent. The activated carbon fines in the effluent accounted for a small proportion of the total particle amount, but the existing bacteria attached to carbon fines may influence the drinking water safety. The disinfection efficiency of desorbed bacteria was lower than that of free bacteria with chlorine, and the disinfection effect on bacteria attached to carbon fines with chloramine was better than that with only chlorine.

  10. Effect of chemical mixing state on the hygroscopicity and cloud nucleation properties of calcium mineral dust particles

    Directory of Open Access Journals (Sweden)

    R. C. Sullivan

    2009-05-01

    Full Text Available Atmospheric mineral dust particles can alter cloud properties and thus climate by acting as cloud condensation nuclei (CCN that form cloud droplets. The CCN activation properties of various calcium mineral dust particles were studied experimentally to investigate the consequences of field observations showing the segregation of sulphate from nitrate and chloride between individual aged Asian dust particles, and the enrichment of oxalic acid in Asian dust. Each mineral's observed apparent hygroscopicity was primarily controlled by its solubility, which determines the degree to which the mineral's intrinsic hygroscopicity can be expressed. The significant increase in hygroscopicity caused by mixing soluble hygroscopic material with insoluble mineral particles is also presented. Insoluble minerals including calcium carbonate, representing fresh unprocessed dust, and calcium sulphate, representing atmospherically processed dust, had similarly small apparent hygroscopicities. Their activation is accurately described by a deliquescence limit following the Kelvin effect and corresponded to an apparent single-hygroscopicity parameter, κ, of ~0.001. Soluble calcium chloride and calcium nitrate, representing atmospherically processed mineral dust particles, were much more hygroscopic, activating similar to ammonium sulphate with κ~0.5. Calcium oxalate monohydrate (κ=0.05 was significantly less CCN-active than oxalic acid (κ=0.3, but not as inactive as its low solubility would predict. These results indicate that the common assumption that all mineral dust particles become more hygroscopic and CCN-active after atmospheric processing should be revisited. Calcium sulphate and calcium oxalate are two realistic proxies for aged mineral dust that remain non-hygroscopic. The dust's apparent hygroscopicity will be controlled by its chemical mixing state, which is determined by its mineralogy and the chemical reaction pathways it experiences

  11. Electronic properties of single crystal CVD diamond and its suitability for particle detection in hadron physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Pomorski, Michal

    2008-08-07

    This work presents the study on the suitability of single-crystal CVD diamond for particle-detection systems in present and future hadron physics experiments. Different characterization methods of the electrical and the structural properties were applied to gain a deeper understanding of the crystal quality and the charge transport properties of this novel semiconductor material. First measurements regarding the radiation tolerance of diamond were performed with sensors heavily irradiated with protons and neutrons. Finally, detector prototypes were fabricated and successfully tested in various experiments as time detectors for minimum ionizing particles as well as for spectroscopy of heavy ions at the energy ranges available at the SIS and the UNILAC facilities of GSI. (orig.)

  12. Electronic properties of single crystal CVD diamond and its suitability for particle detection in hadron physics experiments

    International Nuclear Information System (INIS)

    Pomorski, Michal

    2008-01-01

    This work presents the study on the suitability of single-crystal CVD diamond for particle-detection systems in present and future hadron physics experiments. Different characterization methods of the electrical and the structural properties were applied to gain a deeper understanding of the crystal quality and the charge transport properties of this novel semiconductor material. First measurements regarding the radiation tolerance of diamond were performed with sensors heavily irradiated with protons and neutrons. Finally, detector prototypes were fabricated and successfully tested in various experiments as time detectors for minimum ionizing particles as well as for spectroscopy of heavy ions at the energy ranges available at the SIS and the UNILAC facilities of GSI. (orig.)

  13. Mesoscale Characterization of Fracture Properties of Steel Fiber-Reinforced Concrete Using a Lattice–Particle Model

    Directory of Open Access Journals (Sweden)

    Francisco Montero-Chacón

    2017-02-01

    Full Text Available This work presents a lattice–particle model for the analysis of steel fiber-reinforced concrete (SFRC. In this approach, fibers are explicitly modeled and connected to the concrete matrix lattice via interface elements. The interface behavior was calibrated by means of pullout tests and a range for the bond properties is proposed. The model was validated with analytical and experimental results under uniaxial tension and compression, demonstrating the ability of the model to correctly describe the effect of fiber volume fraction and distribution on fracture properties of SFRC. The lattice–particle model was integrated into a hierarchical homogenization-based scheme in which macroscopic material parameters are obtained from mesoscale simulations. Moreover, a representative volume element (RVE analysis was carried out and the results shows that such an RVE does exist in the post-peak regime and until localization takes place. Finally, the multiscale upscaling strategy was successfully validated with three-point bending tests.

  14. Mesoscale Characterization of Fracture Properties of Steel Fiber-Reinforced Concrete Using a Lattice-Particle Model.

    Science.gov (United States)

    Montero-Chacón, Francisco; Cifuentes, Héctor; Medina, Fernando

    2017-02-21

    This work presents a lattice-particle model for the analysis of steel fiber-reinforced concrete (SFRC). In this approach, fibers are explicitly modeled and connected to the concrete matrix lattice via interface elements. The interface behavior was calibrated by means of pullout tests and a range for the bond properties is proposed. The model was validated with analytical and experimental results under uniaxial tension and compression, demonstrating the ability of the model to correctly describe the effect of fiber volume fraction and distribution on fracture properties of SFRC. The lattice-particle model was integrated into a hierarchical homogenization-based scheme in which macroscopic material parameters are obtained from mesoscale simulations. Moreover, a representative volume element (RVE) analysis was carried out and the results shows that such an RVE does exist in the post-peak regime and until localization takes place. Finally, the multiscale upscaling strategy was successfully validated with three-point bending tests.

  15. Mesoscale Characterization of Fracture Properties of Steel Fiber-Reinforced Concrete Using a Lattice–Particle Model

    Science.gov (United States)

    Montero-Chacón, Francisco; Cifuentes, Héctor; Medina, Fernando

    2017-01-01

    This work presents a lattice–particle model for the analysis of steel fiber-reinforced concrete (SFRC). In this approach, fibers are explicitly modeled and connected to the concrete matrix lattice via interface elements. The interface behavior was calibrated by means of pullout tests and a range for the bond properties is proposed. The model was validated with analytical and experimental results under uniaxial tension and compression, demonstrating the ability of the model to correctly describe the effect of fiber volume fraction and distribution on fracture properties of SFRC. The lattice–particle model was integrated into a hierarchical homogenization-based scheme in which macroscopic material parameters are obtained from mesoscale simulations. Moreover, a representative volume element (RVE) analysis was carried out and the results shows that such an RVE does exist in the post-peak regime and until localization takes place. Finally, the multiscale upscaling strategy was successfully validated with three-point bending tests. PMID:28772568

  16. Morphology, Mechanical Properties and Dimensional Stability of Biomass Particles/High Density Polyethylene Composites: Effect of Species and Composition

    Directory of Open Access Journals (Sweden)

    Binshan Mu

    2018-03-01

    Full Text Available The utilization of four types of biomass particles, including hardwood (poplar, softwood (radiata pine, crop (wheat straw and bamboo (moso bamboo, as reinforcing fillers in preparing high density polyethylene (HDPE based composites was studied. To improve interfacial compatibility, maleic anhydride grafted polyethylene (MAPE was applied as the coupling agent. The effects of the biomass species on the mechanical and water absorption properties of the resulting composites were evaluated based on chemical composition analysis. A creep-recovery test was conducted in single cantilever mode using a dynamic mechanical analyzer. Results show that the four types of biomass particles had similar chemical compositions but different composition contents. Poplar particles with high cellulose content loading in the HDPE matrix exhibited higher tensile and flexure properties and creep resistance. Fracture morphology analysis indicated a weak particle-matrix interface in wheat straw based composites. Given the high crystallinity and minimum hemicellulose content, the moso bamboo reinforced composite showed high impact strength and better water resistance.

  17. Systematic description of the effect of particle shape on the strength properties of granular media

    Directory of Open Access Journals (Sweden)

    Azéma Emilien

    2017-01-01

    Full Text Available In this paper, we explore numerically the effect of particle shape on the mechanical behavior of sheared granular packings. In the framework of the Contact Dynamic (CDMethod, we model angular shape as irregular polyhedral particles, non-convex shape as regular aggregates of four overlapping spheres, elongated shape as rounded cap rectangles and platy shape as square-plates. Binary granular mixture consisting of disks and elongated particles are also considered. For each above situations, the number of face of polyhedral particles, the overlap of spheres, the aspect ratio of elongated and platy particles, are systematically varied from spheres to very angular, non-convex, elongated and platy shapes. The level of homogeneity of binary mixture varies from homogenous packing to fully segregated packings. Our numerical results suggest that the effects of shape parameters are nonlinear and counterintuitive. We show that the shear strength increases as shape deviate from spherical shape. But, for angular shapes it first increases up to a maximum value and then saturates to a constant value as the particles become more angular. For mixture of two shapes, the strength increases with respect of the increase of the proportion of elongated particles, but surprisingly it is independent with the level of homogeneity of the mixture. A detailed analysis of the contact network topology, evidence that various contact types contribute differently to stress transmission at the micro-scale.

  18. Large particles increase viscosity and yield stress of pig cecal contents without changing basic viscoelastic properties.

    Science.gov (United States)

    Takahashi, Toru; Sakata, Takashi

    2002-05-01

    The viscosity of gut contents should influence digestion and absorption. Earlier investigators measured the viscosity of intestinal contents after the removal of solid particles. However, we previously found that removal of solid particles from pig cecal contents dramatically lowered the viscosity of the contents. Accordingly, we examined the contribution of large solid particles to viscoelastic parameters of gut contents in the present study. We removed large particles from pig cecal contents by filtration through surgical gauze. Then, we reconstructed the cecal contents by returning all, one half or none of the original amount of the large particles to the filtrate. We measured the viscosity, shear stress and shear rate of these reconstructed cecal contents using a tube-flow viscometer. The coefficient of viscosity was larger when the large-particle content was higher (P Bingham plastic nature irrespective of large-particle content. We calculated the yield stress of these fluids assuming that the fluids behave as Bingham plastic. The yield stress of the cecal contents was greater (P Bingham plastic characteristics to pig cecal contents.

  19. Physical and Mechanical Properties of LoVAR: A New Lightweight Particle-Reinforced Fe-36Ni Alloy

    Science.gov (United States)

    Stephenson, Timothy; Tricker, David; Tarrant, Andrew; Michel, Robert; Clune, Jason

    2015-01-01

    Fe-36Ni is an alloy of choice for low thermal expansion coefficient (CTE) for optical, instrument and electrical applications in particular where dimensional stability is critical. This paper outlines the development of a particle-reinforced Fe-36Ni alloy that offers reduced density and lower CTE compared to the matrix alloy. A summary of processing capability will be given relating the composition and microstructure to mechanical and physical properties.

  20. A many-particle quantum-kinetic formalism for describing properties of light emitters in frozen dielectrics

    Directory of Open Access Journals (Sweden)

    Gladush M.G.

    2017-01-01

    Full Text Available A many particle quantum-kinetic formalism is suggested to derive the Maxwell-Bloch-type equations which describe the interaction of quantum emitters with light in a frozen dielectric. It is shown that the quantum-kinetic formalism can meet the concept of local variations of dielectric properties and their influence on the emitter. The definitions of the local response and the effective refractive index in macroscopically homogeneous media are discussed.

  1. The mechanical properties of magnesium matrix composites reinforced with 10 wt.% W14Al86 alloy particles

    International Nuclear Information System (INIS)

    Tang, H.G.; Ma, X.F.; Zhao, W.; Cai, S.G.; Zhao, B.; Qiao, Z.H.

    2007-01-01

    The Mg-based metal matrix composite reinforced by 10 wt.% W 14 Al 86 alloy particles has been prepared by mechanical alloying and press-forming process. X-ray diffraction studies confirm the formation of the composite. Microstructure characterization of the samples reveals the uniform distribution of fine W 14 Al 86 alloy. Mechanical properties characterization revealed that the reinforcement of W 14 Al 86 alloy lead to a significant increase in hardness and tensile strength of Mg and AZ91

  2. Bronchial Mucus as a Complex Fluid: Molecular Interactions and Influence of Nanostructured Particles on Rheological and Transport Properties

    Directory of Open Access Journals (Sweden)

    Odziomek Marcin

    2017-06-01

    Full Text Available Transport properties of bronchial mucus are investigated by two-stage experimental approach focused on: (a rheological properties and (b mass transfer rate through the stagnant layer of solutions of mucus components (mucine, DNA, proteins and simulated multi-component mucus. Studies were done using thermostated horizontal diffusion cells with sodium cromoglycate and carminic acid as transferred solutes. Rheological properties of tested liquids was studied by a rotational viscometer and a cone-plate rheometer (dynamic method. First part of the studies demonstrated that inter-molecular interactions in these complex liquids influence both rheological and permeability characteristics. Transfer rate is governed not only by mucus composition and concentration but also by hydrophobic/hydrophilic properties of transported molecules. Second part was focused on the properties of such a layer in presence of selected nanostructured particles (different nanoclays and graphene oxide which may be present in lungs after inhalation. It was shown that most of such particles increase visco-elasticity of the mucus and reduce the rate of mass transfer of model drugs. Measured effects may have adverse impact on health, since they will reduce mucociliary clearance in vivo and slow down drug penetration to the bronchial epithelium during inhalation therapy.

  3. CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: Pair interaction of bilayer-coated nanoscopic particles

    Science.gov (United States)

    Zhang, Qi-Yi

    2009-02-01

    The pair interaction between bilayer membrane-coated nanosized particles has been explored by using the self-consistent field (SCF) theory. The bilayer membranes are composed of amphiphilic polymers. For different system parameters, the pair-interaction free energies are obtained. Particular emphasis is placed on the analysis of a sequence of structural transformations of bilayers on spherical particles, which occur during their approaching processes. For different head fractions of amphiphiles, the asymmetrical morphologies between bilayers on two particles and the inverted micellar intermediates have been found in the membrane fusion pathway. These results can benefit the fabrication of vesicles as encapsulation vectors for drug and gene delivery.

  4. The analysis of composite properties reinforced with particles from palm oil industry waste produced by casting methods

    Science.gov (United States)

    Tugiman; Ariani, F.; Taher, F.; Hasibuan, M. S.; Suprianto

    2017-12-01

    Palm oil processing industries are very attractive because they offer plenty products with high economic value. The CPO factory processes not only produces crude palm oil but also generates fly ash (FA) particles waste in its final process. The purpose of this investigation to analyze and increase the benefits of particles as reinforcement materials for fabricating aluminum matrix composites (AMC’s) by different casting route. Stirring, centrifugal and squeeze casting method was conducted in this study. Further, the chemical composition of FA particles, densities and mechanical properties have been analyzed. The characteristics of composite material were investigated using an Optical microscope, scanning electron microscope (SEM), hardness (Brinell), impact strength (Charpy). The pin on disc method was used to measure the wear rate. The results show that SiO2, Fe2O3, and Al2O3 are the main compounds of fly ash particles. These particles enhanced the hardness and reduce wear resistance of aluminum matrix composites. The squeeze method gives better results than stir and centrifugal casting.

  5. Optical Properties of the Urban Aerosol Particles Obtained from Ground Based Measurements and Satellite-Based Modelling Studies

    Directory of Open Access Journals (Sweden)

    Genrik Mordas

    2015-01-01

    Full Text Available Applications of satellite remote sensing data combined with ground measurements and model simulation were applied to study aerosol optical properties as well as aerosol long-range transport under the impact of large scale circulation in the urban environment in Lithuania (Vilnius. Measurements included the light scattering coefficients at 3 wavelengths (450, 550, and 700 nm measured with an integrating nephelometer and aerosol particle size distribution (0.5–12 μm and number concentration (Dpa > 0.5 μm registered by aerodynamic particle sizer. Particle number concentration and mean light scattering coefficient varied from relatively low values of 6.0 cm−3 and 12.8 Mm−1 associated with air masses passed over Atlantic Ocean to relatively high value of 119 cm−3 and 276 Mm−1 associated with South-Western air masses. Analysis shows such increase in the aerosol light scattering coefficient (276 Mm−1 during the 3rd of July 2012 was attributed to a major Sahara dust storm. Aerosol size distribution with pronounced coarse particles dominance was attributed to the presence of dust particles, while resuspended dust within the urban environment was not observed.

  6. Monodispersepoly[BMA-co-(COPS-I)] Particles by Soap-Free Emulsion Copolymerization and Its Optical Properties as Photonic Crystals.

    Science.gov (United States)

    Lee, Ki Chang; Choo, Hun Seung

    2015-10-01

    In order to study the surfactant-free emulsion copolymerization of benzyl methacrylate (BMA) with sodium 1-allyloxy-2-hydroxypropane sulfonate (COPS-I) and the resulting optical properties, a series of experiments was carried out at various reaction conditions such as the changes of BMA concentration, COPS-I concentration, BMA concentration under a fixed COPS-I amount, initiator and divinyl benzene (DVB) concentration. All the latices showed highly monodispersed spherical particles in the size range of 144~435 nm and the respective shiny structural colors from their colloidal photonic crystals. It is found that the changes in such polymerization factors greatly affect the number of particles and particle diameter, polymerization rate, molecular weight, zeta-potential, and refractive indices. The increase of number of particles led to the increased rate of polymerization and zeta-potential of the latices, on the other hand, to the decreased molecular weight. Refractive indices and the reflectivity increased with COPS-I concentration, on the other hand, and decreased with DVB concentration. Especially, refractive indices of the resulting poly[BMA-co-(COPS-I)] colloidal photonic crystals showed much higher values of 1.65~2.21 than that of polystyrene, due to the formation of core-shell shaped morphology. Monodisperse and high refractive index of poly[BMA-co-(COPS-I)] particles prepared in this work could be used for the study in photonic crystals and electrophoretic display.

  7. Effect of Mineral Filler Type and Particle Size on the Engineering Properties of Stone Mastic Asphalt Pavements

    Directory of Open Access Journals (Sweden)

    R Muniandy

    2013-12-01

    Full Text Available This study examines four types of industrial and by-product waste fillers, namely limestone dust (LSD, which was the reference filler; ceramic waste dust (CWD; coal fly ash (CFA, and steel slag mixture (SSD. The filler consisted of an aggregate (10% of total weight with three proportions: 100% passing 75μm, 50% passing 75μm/20μm, and 100% passing 20μm. Comprehensive laboratory tests were performed to determine the impact of different types and particle sizes of fillers on the engineering and mechanical properties of fine mastics and stone mastic asphalt mixture. The results indicate that the application of industrial by-products used as fillers improves the engineering properties of stone mastic asphalt mixtures. The increased stiffness due to the addition of the filler is represented by an increase in the softening point, viscosity, stability, and resilient modulus, as well as a decrease in penetration. The optimum asphalt content increased with the decrease in filler particle size for LSD and SSD, and decreased for CWD and CFA. It was also determined that the filler type and particle size has a significant effect on the mixture properties. Among these three proportions, the samples prepared with the filler size proportion of 50/50 gave the best value in terms of stability, Marshall quotient, and resilient modulus than the other filler size proportions.

  8. Influence of high-dose gamma radiation and particle size on antioxidant properties of Maize ( Zea mays L.) flour

    International Nuclear Information System (INIS)

    Nawaz, Haq; Shad, Muhammad Aslam; Rehman, Tanzila; Ramzan, Ayesha

    2016-01-01

    Influence of high-dose gamma radiation and particle size on antioxidant properties of maize (Zea mays L.) flour was studied using response surface methodology. A central composite design based on three levels of each of particle size, in terms of mesh number (40, 60 and 80 meshes), and gamma radiation dose (25, 50 and 75 kGy) was constructed. A statistically significant dose-dependent decrease (p<0.05) in antioxidant properties of gamma irradiated flour was observed. However, an increase in the mesh number (decrease in particle size of flour) resulted in an increase in antioxidant properties. The optimum level of radiation dose to achieve maximum value of responses was found to be 50 kGy for Trolox equivalent total antioxidant activity (TETAOA), 25 kGy for iron chelating ability (ICA), 25 kGy for reducing power (RP) and 75 kGy for linoleic acid reduction capacity (LARC). However, the optimum level of mesh number to achieve desired levels of TETAOA, ICA, RP and LARC was found to be 80 meshes. (author)

  9. Influence of high-dose gamma radiation and particle size on antioxidant properties of Maize ( Zea mays L.) flour

    Energy Technology Data Exchange (ETDEWEB)

    Nawaz, Haq; Shad, Muhammad Aslam; Rehman, Tanzila; Ramzan, Ayesha, E-mail: haqnawaz@bzu.edu.pk [Bahauddin Zakariya University, Multan (Pakistan)

    2016-10-15

    Influence of high-dose gamma radiation and particle size on antioxidant properties of maize (Zea mays L.) flour was studied using response surface methodology. A central composite design based on three levels of each of particle size, in terms of mesh number (40, 60 and 80 meshes), and gamma radiation dose (25, 50 and 75 kGy) was constructed. A statistically significant dose-dependent decrease (p<0.05) in antioxidant properties of gamma irradiated flour was observed. However, an increase in the mesh number (decrease in particle size of flour) resulted in an increase in antioxidant properties. The optimum level of radiation dose to achieve maximum value of responses was found to be 50 kGy for Trolox equivalent total antioxidant activity (TETAOA), 25 kGy for iron chelating ability (ICA), 25 kGy for reducing power (RP) and 75 kGy for linoleic acid reduction capacity (LARC). However, the optimum level of mesh number to achieve desired levels of TETAOA, ICA, RP and LARC was found to be 80 meshes. (author)

  10. Simultaneous measurement of local particle movement, solids concentrations and bubble properties in fluidized bed reactors using a novel fiber optical technique

    Energy Technology Data Exchange (ETDEWEB)

    Tayebi, Davoud

    1999-12-31

    This thesis develops a new method for simultaneous measurements of local flow properties in highly concentrated multiphase flow systems such as gas-solid fluidized bed reactors. The method is based on fiber optical technique and tracer particles. A particle present in the measuring volume in front of the probe is marked with a fluorescent dye. A light source illuminates the particles and the detecting fibres receive reflected light from uncoated particles and fluorescent light from the tracer particle. Using optical filters, the fluorescent light can be distinguished and together with a small fraction of background light from uncoated particles can be used for determination of local flow properties. Using this method, one can simultaneously measure the local movement of a single tracer particle, local bubble properties and the local solids volume fractions in different positions in the bed. The method is independent of the physical properties of the tracer particles. It is also independent of the local solids concentrations in the range of 0 to 60 vol.-%, but is mainly designed for highly concentrated flow systems. A computer programme that uses good signals from at least three sensors simultaneously to calculate the tracer particle velocity in two dimensions have been developed. It also calculates the bubble properties and local solids volume fractions from the same time series. 251 refs., 150 figs., 5 tabs.

  11. Simultaneous measurement of local particle movement, solids concentrations and bubble properties in fluidized bed reactors using a novel fiber optical technique

    Energy Technology Data Exchange (ETDEWEB)

    Tayebi, Davoud

    1998-12-31

    This thesis develops a new method for simultaneous measurements of local flow properties in highly concentrated multiphase flow systems such as gas-solid fluidized bed reactors. The method is based on fiber optical technique and tracer particles. A particle present in the measuring volume in front of the probe is marked with a fluorescent dye. A light source illuminates the particles and the detecting fibres receive reflected light from uncoated particles and fluorescent light from the tracer particle. Using optical filters, the fluorescent light can be distinguished and together with a small fraction of background light from uncoated particles can be used for determination of local flow properties. Using this method, one can simultaneously measure the local movement of a single tracer particle, local bubble properties and the local solids volume fractions in different positions in the bed. The method is independent of the physical properties of the tracer particles. It is also independent of the local solids concentrations in the range of 0 to 60 vol.-%, but is mainly designed for highly concentrated flow systems. A computer programme that uses good signals from at least three sensors simultaneously to calculate the tracer particle velocity in two dimensions have been developed. It also calculates the bubble properties and local solids volume fractions from the same time series. 251 refs., 150 figs., 5 tabs.

  12. Effect of particle size of granules on some mechanical properties of ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... compacts formed from larger granules as a result of plastic deformation and fragmentation than ... whether an increase or a decrease in particle size will ... many) was used for the preparation of the tablets from the various.

  13. Contribution of silicon recombination properties in resolution of short-range particle detectors

    International Nuclear Information System (INIS)

    Verbitskaya, E.M.; Eremin, V.K.; Malyarenko, A.M.; Strokan, N.B.; Sukhanov, V.L.

    1987-01-01

    Tracks of short-range particles represent dense clusters of electron-hole pairs 2-4 μm in diameter and 20-30 μm long. Thus, conditions for charge carrier transport in microscopic Si volume are discovered at registration of each particle. Statistical distribution by the specimen square of the main parameter - lifetime of charge carriers (τ) is disclosed as a result of particle chaotic hitting the detector. Analytical description for the shape of the spectral line of the detector is found in the assumption of Gauss distribution τ. The function is applied to the analysis of detector spectra with maximum energy resolution, for which contributions to the shape of the line of the fundamental factors and nonperfection of Si or of the detector structure as a whole are comparable. Excess fluctuations of α-particle energy transformation to the charge of electron-hole pairs are found relatively to adopted values

  14. Contribution of silicon recombination properties in resolution of short-range particle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Verbitskaya, E M; Eremin, V K; Malyarenko, A M; Strokan, N B; Sukhanov, V L

    1987-10-01

    Tracks of short-range particles represent dense clusters of electron-hole pairs 2-4 ..mu..m in diameter and 20-30 ..mu..m long. Thus, conditions for charge carrier transport in microscopic Si volume are discovered at registration of each particle. Statistical distribution by the specimen square of the main parameter - lifetime of charge carriers (tau) is disclosed as a result of particle chaotic hitting the detector. Analytical description for the shape of the spectral line of the detector is found in the assumption of Gauss distribution tau. The function is applied to the analysis of detector spectra with maximum energy resolution, for which contributions to the shape of the line of the fundamental factors and nonperfection of Si or of the detector structure as a whole are comparable. Excess fluctuations of ..cap alpha..-particle energy transformation to the charge of electron-hole pairs are found relatively to adopted values.

  15. Symmetry properties of the transport coefficients of charged particles in disordered materials

    International Nuclear Information System (INIS)

    Baird, J.K.

    1979-01-01

    The transport coefficients of a charged particle in an isotropic material are shown to be even functions of the applied electric field. We discuss the limitation which this result and its consequences place upon formulae used to represent these coefficients

  16. Study of the structural and magnetic properties of metallic iron-hematite particles for use in magnetorheological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Osorio Ospina, Diana Marcela; Castro Navas, Irvin Jadway [Universidad del Valle, Escuela de Ingenieria de Materiales (Colombia); Perez Alcazar, German Antonio; Tabares, Jesus Anselmo, E-mail: jesus_tabares_8@hotmail.com [Universidad del Valle, Departamento de Fisica (Colombia)

    2012-03-15

    Magnetorheological (MR) fluids are new iron-based materials, whose applications include brakes, dampers, clutches, shock absorbers systems and polishing of optical surfaces (lens and mirrors). They are dependent on the size and shape of particles as the magnetic properties. Interested in the possibility of using iron-rich powders, commonly used in nondestructive testing, ranging in size from a few {mu}m to about 200 {mu}m and lower cost than those commercially used for MR fluids, a study of the structural and magnetic properties of iron-rich metallic particles by X-ray diffraction (XRD) and Moessbauer spectroscopy (MS) at room temperature has been done. Powders, as received, were separated into particle sizes smaller than 20 {mu}m (sample A) and in the range of 20-38 {mu}m (sample B) because these are the sizes generally required for applications in MR fluids. The particles whose sizes exceed the above values were ground in a high energy planetary mill for 3 h, using different values of rotational speed/time: 200 rpm for one hour, a pause of 10 s, 140 rpm for one hour, pause 10 s and then 175 rpm during the last hour. These powders were sieved to obtain particles smaller than 20 {mu}m (sample C). According XRD results, in all samples, only {alpha}-Fe (lattice parameter a = 2,867(2) Angstrom-Sign ) and Fe{sub 2}O{sub 3} (lattice parameter a 5,037(1) Angstrom-Sign and c = 13,755(8) Angstrom-Sign ) were present. The Moessbauer spectra were fitted with two sextets. The hyperfine parameters values allowed us to assign the highest relative area spectrum (sextet) corresponding to {alpha}-Fe and the second one to Fe{sub 2}O{sub 3} in accord to the XRD results. Thus, the preparation method using mechanical milling for diminishing the size of the metallic particles allowed us to get particles with size and magnetic properties that could lead to potentially MR fluids applications.

  17. Study of the structural and magnetic properties of metallic iron-hematite particles for use in magnetorheological fluids

    International Nuclear Information System (INIS)

    Osorio Ospina, Diana Marcela; Castro Navas, Irvin Jadway; Pérez Alcázar, German Antonio; Tabares, Jesus Anselmo

    2012-01-01

    Magnetorheological (MR) fluids are new iron-based materials, whose applications include brakes, dampers, clutches, shock absorbers systems and polishing of optical surfaces (lens and mirrors). They are dependent on the size and shape of particles as the magnetic properties. Interested in the possibility of using iron-rich powders, commonly used in nondestructive testing, ranging in size from a few μm to about 200 μm and lower cost than those commercially used for MR fluids, a study of the structural and magnetic properties of iron-rich metallic particles by X-ray diffraction (XRD) and Mössbauer spectroscopy (MS) at room temperature has been done. Powders, as received, were separated into particle sizes smaller than 20 μm (sample A) and in the range of 20–38 μm (sample B) because these are the sizes generally required for applications in MR fluids. The particles whose sizes exceed the above values were ground in a high energy planetary mill for 3 h, using different values of rotational speed/time: 200 rpm for one hour, a pause of 10 s, 140 rpm for one hour, pause 10 s and then 175 rpm during the last hour. These powders were sieved to obtain particles smaller than 20 μm (sample C). According XRD results, in all samples, only α-Fe (lattice parameter a = 2,867(2) Å) and Fe 2 O 3 (lattice parameter a 5,037(1) Å and c = 13,755(8) Å) were present. The Mössbauer spectra were fitted with two sextets. The hyperfine parameters values allowed us to assign the highest relative area spectrum (sextet) corresponding to α-Fe and the second one to Fe 2 O 3 in accord to the XRD results. Thus, the preparation method using mechanical milling for diminishing the size of the metallic particles allowed us to get particles with size and magnetic properties that could lead to potentially MR fluids applications.

  18. Synthesis and hyperthermia property of hydroxyapatite-ferrite hybrid particles by ultrasonic spray pyrolysis

    International Nuclear Information System (INIS)

    Inukai, Akihiro; Sakamoto, Naonori; Aono, Hiromichi; Sakurai, Osamu; Shinozaki, Kazuo; Suzuki, Hisao; Wakiya, Naoki

    2011-01-01

    Biocompatible hybrid particles composed of hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HAp) and ferrite (γ-Fe 2 O 3 and Fe 3 O 4 ) were synthesized using a two-step procedure. First, the ferrite particles were synthesized by co-precipitation. Second, the suspension, which was composed of ferrite particles by a co-precipitation method, Ca(NO 3 ) 2 , and H 3 PO 4 aqueous solution with surfactant, was nebulized into mist ultrasonically. Then the mist was pyrolyzed at 1000 o C to synthesize HAp-ferrite hybrid particles. The molar ratio of Fe ion and HAp was (Fe 2+ and Fe 3+ )/HAp=6. The synthesized hybrid particle was round and dimpled, and the average diameter of a secondary particle was 740 nm. The cross section of the synthesized hybrid particles revealed two phases: HAp and ferrite. The ferrite was coated with HAp. The synthesized hybrid particles show a saturation magnetization of 11.8 emu/g. The net saturation magnetization of the ferrite component was calculated as 32.5 emu/g. The temperature increase in the AC-magnetic field (370 kHz, 1.77 kA/m) was 9 o C with 3.4 g (the ferrite component was 1.0 g). These results show that synthesized hybrid particles are biocompatible and might be useful for magnetic transport and hyperthermia studies. - Research Highlights: → Biocompatible hybrid particles composed of hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HAp) and ferrite (γ-Fe 2 O 3 and Fe 3 O 4 ) were synthesized using a two-step synthesis, which is comprised of co-precipitation and ultrasonic spray pyrolysis. → Cross sectional TEM observation and X-ray diffraction revealed that synthesized hybrid particles showed two phases (HAp and ferrite), and the ferrite was coated with HAp. → The saturation magnetization of ferrite in the HAp-ferrite hybrid was 32.49 emu/g. → The increased temperature in the AC-magnetic field (370 kHz, 1.77 kA/m) was 9 o C with 3.4 g (the ferrite component was 1.0 g).

  19. The influence of powder particle size on properties of Cu-Al2O3 composites

    Directory of Open Access Journals (Sweden)

    Rajković V.

    2009-01-01

    Full Text Available Inert gas atomized prealloyed copper powder containing 2 wt.% Al (average particle size ≈ 30 μm and a mixture consisting of copper (average particle sizes ≈ 15 μm and 30 μm and 4 wt.% of commercial Al2O3 powder particles (average particle size ≈ 0.75 μm were milled separately in a high-energy planetary ball mill up to 20 h in air. Milling was performed in order to strengthen the copper matrix by grain size refinement and Al2O3 particles. Milling in air of prealloyed copper powder promoted formation of finely dispersed nano-sized Al2O3 particles by internal oxidation. On the other side, composite powders with commercial micro-sized Al2O3 particles were obtained by mechanical alloying. Following milling, powders were treated in hydrogen at 400 0C for 1h in order to eliminate copper oxides formed on their surface during milling. Hot-pressing (800 0C for 3 h in argon at pressure of 35 MPa was used for compaction of milled powders. Hot-pressed composite compacts processed from 5 and 20 h milled powders were additionally subjected to high temperature exposure (800°C for 1 and 5h in argon in order to examine their thermal stability. The results were discussed in terms of the effects of different size of starting powders, the grain size refinement and different size of Al2O3 particles on strengthening, thermal stability and electrical conductivity of copper-based composites.

  20. The effect of particle size and concentration on the flow properties of a homogeneous slurry

    International Nuclear Information System (INIS)

    Abbas, M.A.; Crowe, C.T.

    1986-01-01

    This paper presents the results of the effects of particle size and concentration on the velocity distribution in the fully developed flow of a homogeneous slurry. The slurry consisted of chloroform and silica gel with matched index of refraction to enable Laser-Doppler anemometry (LDA) measurements through the mixture. Slurries with two particle sizes and solids concentration up to 30% by volume were studied. Measurements were made over a Reynolds number range of 1,200 to 30,000

  1. Employment of the porous particles for preparation of the capsules containing aspirin and drug release property

    International Nuclear Information System (INIS)

    Hosoi, Fumio; Makuuchi, Keizo; Saito, Kenji; Koishi, Masumi.

    1985-01-01

    Polymer-coated porous particles containing aspirin as a drug were prepared and the rate of release of aspirin was studied. The impregnation of aspirin was carried out by post-graft polymerization, where methyl methacrylate or methacrylic acid was treated with porous particles, pre-irradiated with γ-ray from 60 Co, in the presence of aspirin. Release of aspirin from modified particles was tested with 50 % methanol solution and/or pH 5.2 buffer solution of acetic acid. The amount of aspirin released from capsules increased with time and reached a constant values after 140 h. The amount of aspirin absorbed in porous particles was increased with graft polymerization. In addition, absorption of aspirin in porous particles was significantly enhanced by treating the particle surface with TiO 2 before irradiation. The amount of aspirin released was linearly to the square root of time. It was concluded that the diffusion of aspirin through the polymer matrix was the rate limiting step. (author)

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

    Science.gov (United States)

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

    2016-08-01

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

  3. Fabrication of Superhydrophobic Surface with Controlled Wetting Property by Hierarchical Particles.

    Science.gov (United States)

    Xu, Jianxiong; Liu, Weiwei; Du, Jingjing; Tang, Zengmin; Xu, Lijian; Li, Na

    2015-04-01

    Hierarchical particles were prepared by synthetically joining appropriately functionalized polystyrene spheres of poly[styrene-co-(3-(4-vinylphenyl)pentane-2,4-dione)] (PS-co-PVPD) nanoparticles and poly(styrene-co-chloromethylstyrene) (PS-co-PCMS) microparticles. The coupling reaction of nucleophilic substitution of pendent β-diketone groups with benzyl chloride was used to form the hierarchical particles. Since the polymeric nanoparticles and microparticles were synthesized by dispersion polymerization and emulsion polymerization, respectively, both the core microparticles and the surface nanoparticles can be different size and chemical composition. By means of changing the size of the PS-co-PVPD surface nanoparticles, a series of hierarchical particles with different scale ratio of the micro/nano surface structure were successfully prepared. Moreover, by employing the PS-co-PVPD microparticles and PS-co-PCMS nanoparticles as building blocks, hierarchical particles with surface nanoaprticles of different composition were made. These as-prepared hierarchical particles were subsequently assembled on glass substrates to form particulate films. Contact angle measurement shows that superhydrophobic surfaces can be obtained and the contact angle of water on the hierarchically structured surface can be adjusted by the scale ratio of the micro/nano surface structure and surface chemical component of hierarchical particles.

  4. Laboratory and modeling studies on the effects of water and soot emissions and ambient conditions on the properties of contrail ice particles in the jet regime

    Directory of Open Access Journals (Sweden)

    H.-W. Wong

    2013-10-01

    Full Text Available Contrails and contrail-induced cirrus clouds are identified as the most uncertain components in determining aviation impacts on global climate change. Parameters affecting contrail ice particle formation immediately after the engine exit plane (< 5 s in plume age may be critical to ice particle properties used in large-scale models predicting contrail radiative forcing. Despite this, detailed understanding of these parametric effects is still limited. In this paper, we present results from recent laboratory and modeling studies conducted to investigate the effects of water and soot emissions and ambient conditions on near-field formation of contrail ice particles and ice particle properties. The Particle Aerosol Laboratory (PAL at the NASA Glenn Research Center and the Aerodyne microphysical parcel model for contrail ice particle formation were employed. Our studies show that exhaust water concentration has a significant impact on contrail ice particle formation and properties. When soot particles were introduced, ice particle formation was observed only when exhaust water concentration was above a critical level. When no soot or sulfuric acid was introduced, no ice particle formation was observed, suggesting that ice particle formation from homogeneous nucleation followed by homogeneous freezing of liquid water was unfavorable. Soot particles were found to compete for water vapor condensation, and higher soot concentrations emitted into the chamber resulted in smaller ice particles being formed. Chamber conditions corresponding to higher cruising altitudes were found to favor ice particle formation. The microphysical model captures trends of particle extinction measurements well, but discrepancies between the model and the optical particle counter measurements exist as the model predicts narrower ice particle size distributions and ice particle sizes nearly a factor of two larger than measured. These discrepancies are likely due to particle

  5. Morphology and mechanical properties of poly(β-hydroxybutyrate)/poly(ε-caprolactone) blends controlled with cellulosic particles.

    Science.gov (United States)

    Chen, Jianxiang; Wang, Yuankun; Yin, Zeren; Tam, Kam C; Wu, Defeng

    2017-10-15

    The rigid microcrystalline cellulose (MCC) particles and semi-rigid ethyl cellulose (EC) were used to control phase morphology and mechanical properties of immiscible poly(β-hydroxybutyrate) (PHB)/poly(ε-caprolactone) (PCL) blends. The interfacial properties were evaluated by the fiber retraction and contact angle methods MCC is incompatible with PHB and PCL, and dispersed independently in the two polymer phases in their blends. However, EC is more compatible with the two polymers, with a higher affinity for PCL. And EC prefers locating in PCL domains and at the phase interface. Selective localization of MCC and EC affects the mechanical properties and phase structure of PHB/PCL blends strongly. For the co-continuous samples, the presence of MCC and EC improves both the tensile and impact strengths. For the 'sea-island' ones, however, the changes of strengths depends strongly on the phase adhesion. This work will help focus efforts on moderating structure and properties of immiscible polymer blends using cellulose particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. The effect of reinforcement percentages on properties of copper matrix composites reinforced with TiC particles

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, GH.A., E-mail: Gh.a.bagheri65@gmail.com

    2016-08-15

    In this research, copper matrix composites reinforced with different amounts of titanium carbide particles were produced by mechanical milling and in-situ formation of reinforcements. Morphology and size of milled powders were inspected by scanning electron microscopy (SEM) several times during milling process. Changes in lattice parameter, crystallite size, lattice strain, dislocation density and Gibbs free energy changes (due to increasing in dislocation densities and grain boundaries) in different samples (with different TiC particles contents) were studied by X-Ray Diffraction technique with Cu-kα radiation and using Nelson–Riley method and Williamson–Hall equation. Microstructure of samples after sintering was investigated by FESEM. Finally, densitometry, hardness, determination of electrical resistance and pin on disk wear test were performed and effect of reinforcement percentages on the physical and mechanical properties of composites was studied. Results show incredible improvement in mechanical properties with increasing in TiC value, even though, electrical conductivity dropped off considerably. - Highlights: • Microstructures, mechanical and physical properties of composites have been studied. • Stored Gibbs free energy of dislocations and grain boundaries has been calculated. • Gibbs free energy increased with increasing in titanium percent. • Higher TiC percentage led to better mechanical and unfavorable physical properties.

  7. Magnetic properties in an ash flow tuff with continuous grain size variation: a natural reference for magnetic particle granulometry

    Science.gov (United States)

    Till, J.L.; Jackson, M.J.; Rosenbaum, J.G.; Solheid, P.

    2011-01-01

    The Tiva Canyon Tuff contains dispersed nanoscale Fe-Ti-oxide grains with a narrow magnetic grain size distribution, making it an ideal material in which to identify and study grain-size-sensitive magnetic behavior in rocks. A detailed magnetic characterization was performed on samples from the basal 5 m of the tuff. The magnetic materials in this basal section consist primarily of (low-impurity) magnetite in the form of elongated submicron grains exsolved from volcanic glass. Magnetic properties studied include bulk magnetic susceptibility, frequency-dependent and temperature-dependent magnetic susceptibility, anhysteretic remanence acquisition, and hysteresis properties. The combined data constitute a distinct magnetic signature at each stratigraphic level in the section corresponding to different grain size distributions. The inferred magnetic domain state changes progressively upward from superparamagnetic grains near the base to particles with pseudo-single-domain or metastable single-domain characteristics near the top of the sampled section. Direct observations of magnetic grain size confirm that distinct transitions in room temperature magnetic susceptibility and remanence probably denote the limits of stable single-domain behavior in the section. These results provide a unique example of grain-size-dependent magnetic properties in noninteracting particle assemblages over three decades of grain size, including close approximations of ideal Stoner-Wohlfarth assemblages, and may be considered a useful reference for future rock magnetic studies involving grain-size-sensitive properties.

  8. Hygroscopic properties of atmospheric particles emitted during wintertime biomass burning episodes in Athens

    Science.gov (United States)

    Psichoudaki, Magda; Nenes, Athanasios; Florou, Kalliopi; Kaltsonoudis, Christos; Pandis, Spyros N.

    2018-04-01

    This study explores the Cloud Condensation Nuclei (CCN) activity of atmospheric particles during intense biomass burning periods in an urban environment. During a one-month campaign in the center of Athens, Greece, a CCN counter coupled with a Scanning Mobility Particle Sizer (SMPS) and a high resolution Aerosol Mass Spectrometer (HR-AMS) were used to measure the size-resolved CCN activity and composition of the atmospheric aerosols. During the day, the organic fraction of the particles was more than 50%, reaching almost 80% at night, when the fireplaces were used. Positive Matrix Factorization (PMF) analysis revealed 4 factors with biomass burning being the dominant source after 18:00 until the early morning. The CCN-based overall hygroscopicity parameter κ ranged from 0.15 to 0.25. During the night, when the biomass burning organic aerosol (bbOA) dominated, the hygroscopicity parameter for the mixed organic/inorganic particles was on average 0.16. The hygroscopicity of the biomass-burning organic particles was 0.09, while the corresponding average value for all organic particulate matter during the campaign was 0.12.

  9. Particle size distribution properties in mixed-phase monsoon clouds from in situ measurements during CAIPEEX

    Science.gov (United States)

    Patade, Sachin; Prabha, T. V.; Axisa, D.; Gayatri, K.; Heymsfield, A.

    2015-10-01

    A comprehensive analysis of particle size distributions measured in situ with airborne instrumentation during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) is presented. In situ airborne observations in the developing stage of continental convective clouds during premonsoon (PRE), transition, and monsoon (MON) period at temperatures from 25 to -22°C are used in the study. The PRE clouds have narrow drop size and particle size distributions compared to monsoon clouds and showed less development of size spectra with decrease in temperature. Overall, the PRE cases had much lower values of particle number concentrations and ice water content compared to MON cases, indicating large differences in the ice initiation and growth processes between these cloud regimes. This study provided compelling evidence that in addition to dynamics, aerosol and moisture are important for modulating ice microphysical processes in PRE and MON clouds through impacts on cloud drop size distribution. Significant differences are observed in the relationship of the slope and intercept parameters of the fitted particle size distributions (PSDs) with temperature in PRE and MON clouds. The intercept values are higher in MON clouds than PRE for exponential distribution which can be attributed to higher cloud particle number concentrations and ice water content in MON clouds. The PRE clouds tend to have larger values of dispersion of gamma size distributions than MON clouds, signifying narrower spectra. The relationships between PSDs parameters are presented and compared with previous observations.

  10. Synthesis of nanosilver particles by reverse micelle method and study of their bactericidal properties

    Energy Technology Data Exchange (ETDEWEB)

    Tran Thi Ngoc Dung; Ngo Quoc Buu; Dang Viet Quang; Le Anh Bang; Nguyen Hoai Chau; Nguyen Thi Ly [Institute of Environmental Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay Distr., Hanoi (Viet Nam); Huynh Thi Ha [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay Distr., Hanoi (Viet Nam); Nguyen Vu Trung [National Institute for Infectious and Tropical Diseases, 1 Ton That Tung, Dong Da Distr., Hanoi (Viet Nam)], E-mail: ttndzung@yahoo.com, E-mail: buu_nq@yahoo.com

    2009-09-01

    Nanosilver particles have been synthesized by the reverse micelle method, where AgNO{sub 3} was used as a silver ions source, NaBH{sub 4} and quercetin - as reducing agents, CTAB, SDOSS and AOT- as surfactants, while the stabilizer was Vietnamese chitosan. Studying the factors influencing the process of nanosilver particle formation, it was shown that the particle size of the nanosilver products depends on the concentration of the reaction components and their stoichiometric ratio. It was also shown that the reaction system using AOT surfactant is capable of producing nanosilver particles with smallest nanoparticles ({phi}{sub av} {approx} 5 nm) and good particle-size distribution. The study on bactericidal activity of the nanosilver products indicated that the disinfecting solution with a nanosilver concentration of 3 ppm was able to inhibit all E.coli and Coliforms, TPC and fungi at 15 ppm, while Vibrio cholerae cells were inactivated completely with 0.5 ppm of nanosilver after 30 minutes exposition.

  11. Processing, microstructure and mechanical properties of nickel particles embedded aluminium matrix composite

    International Nuclear Information System (INIS)

    Yadav, Devinder; Bauri, Ranjit

    2011-01-01

    Research highlights: → Al-Ni particle composite was successfully processed by FSP. → No harmful intermetallics formed. → The composite showed a 3 fold increase in yield strength with high ductility. → FSP also lead to a refined recrystallized grain structure. → A continuous type dynamic recrystallization process seems to be working during FSP. - Abstract: Nickel particles were embedded into an Al matrix by friction stir processing (FSP) to produce metal particle reinforced composite. FSP resulted in uniform dispersion of nickel particles with excellent interfacial bonding with the Al matrix and also lead to significant grain refinement of the matrix. The novelty of the process is that the composite was processed in one step without any pretreatment being given to the constituents and no harmful intermetallic formed. The novel feature of the composite is that it shows a three fold increase in the yield strength while appreciable amount of ductility is retained. The hardness also improved significantly. The fracture surface showed a ductile failure mode and also revealed the superior bonding between the particles and the matrix. Electron backscattered diffraction (EBSD) and transmission electron microscopy analysis revealed a dynamically recrystallized equiaxed microstructure. A gradual increase in misorientation from sub-grain to high-angle boundaries is observed from EBSD analysis pointing towards a continuous type dynamic recrystallization mechanism.

  12. Flow properties and chemical composition of carob (Ceratonia siliqua L.) flours as related to particle size and seed presence.

    Science.gov (United States)

    Benković, Maja; Belščak-Cvitanović, Ana; Bauman, Ingrid; Komes, Draženka; Srečec, Siniša

    2017-10-01

    Due to abundance in carbohydrates, dietary fibres and bioactive compounds, as well as for its outspread and low prices, carob (Ceratonia siliqua L.) flour has a great potential of use as a functional ingredient. The aim of this study was to analyse this potential by physical and chemical properties assessment of different particle sizes of carob flour with and without seeds. The influence of seed presence on physical and chemical properties of flour was also investigated. Seed presence in carob flour led to higher cohesivity and cake strength. It also affected the extraction efficiency of polyphenols, which was confirmed by the ranking of samples according to their procyanidin and tannins contents. With regard to the carbohydrate content, significant differences (Pflours. These findings confirm the importance of understanding physical and chemical properties of carob flours in order to use them efficiently as a functional food ingredient. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Accounting for particle non-sphericity in modeling of mineral dust radiative properties in the thermal infrared

    International Nuclear Information System (INIS)

    Legrand, M.; Dubovik, O.; Lapyonok, T.; Derimian, Y.

    2014-01-01

    Spectral radiative parameters (extinction optical depth, single scattering albedo, asymmetry factor) of spheroids of mineral dust composed of quartz and clays have been simulated at wavelengths between 7.0 and 10.2 µm using a T-matrix code. In spectral intervals with high values of complex index of refraction and for large particles, the parameters cannot be fully calculated with the code. Practically, the calculations are stopped at a truncation radius over which the particles contribution cannot thus be taken into account. To deal with this issue, we have developed and applied an accurate corrective technique of T-matrix Size Truncation Compensation (TSTC). For a mineral dust described by its AERONET standard aspect ratio (AR) distribution, the full error margin when applying the TSTC is within 0.3% (or ±0.15%), whatever the radiative parameter and the wavelength considered, for quartz (the most difficult case). Large AR values limit also the possibilities of calculation with the code. The TSTC has been able to complete the calculations of the T-matrix code for a modified AERONET AR distribution with a maximum AR of 4.7 instead of 3 for the standard distribution. Comparison between the simulated properties of spheroids and of spheres of same volume confirms, in agreement with the literature, that significant differences are observed in the vicinity of the mineral resonant peaks (λ ca. 8.3–8.7 µm for quartz, ca. 9.3–9.5 µm for clays) and that they are due to absorption by the small particles. This is a favorable circumstance for the TSTC, which is concerned with the contribution of the largest particles. This technique of numerical calculation improves the accuracy of the simulated radiative parameters of mineral dust, which must lead to a progress in view of applications such as remote sensing or determination of energy balance of dust in the thermal infrared (TIR), incompletely investigated so far. - Highlights: • Completion of computation of mineral

  14. Mechanical, thermal and friction properties of rice bran carbon/nitrile rubber composites: Influence of particle size and loading

    International Nuclear Information System (INIS)

    Li, Mei-Chun; Zhang, Yinhang; Cho, Ur Ryong

    2014-01-01

    Highlights: • A novel rice bran carbon (RBC) is used to reinforce nitrile rubber. • We study the effect of RBC particle size on the performances of nitrile rubber. • We study the effect of RBC loading on the performances of nitrile rubber. • The addition of RBC improves the mechanical properties of nitrile rubber. • The addition of RBC improves the anti-skid properties of nitrile rubber. - Abstract: Four types of rice bran carbon (RBC) with different particle sizes were compounded with nitrile rubber (NBR) in a laboratory size two-roll miller. The obtained RBC/NBR composites were characterized using Field Emission Scanning Electron Microscopy (FE-SEM) and tensile tests. Experimental results showed the RBC with lowest particle size exhibited best dispersion state and superior reinforcement ability. Then, we investigated the influence of RBC loading on the morphology, vulcanization characteristics, mechanical, thermal and friction properties of NBR composites. Experimental results indicated that the incorporation of RBC resulted in higher torque values, longer curing time, but shorter scorch time. The addition of RBC remarkably improved the mechanical properties of NBR composites. However, when the RBC loading exceeded 60 phr, the improvement in the tensile strength was not significant due to the poor dispersion state and weak interfacial bonding between RBC and NBR matrix, which were confirmed by Mooney–Rivlin stress–strain curves and FE-SEM observations. The thermal stabilities of RBC/NBR composites were largely improved as the loading of RBC increased. Friction tests revealed that under a certain concentration, the presence of RBC increased the static friction coefficient of NBR composites, suggesting the anti-skid role of RBC in the NBR composites. The overall results demonstrated that RBC could act as ideal filler for NBR composites providing both economic and environmental advantages

  15. Standard Practice for Measurement of Mechanical Properties During Charged-Particle Irradiation

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1996-01-01

    1.1 This practice covers the performance of mechanical tests on materials being irradiated with charged particles. These tests are designed to simulate or provide understanding of, or both, the mechanical behavior of materials during exposure to neutron irradiation. Practices are described that govern the test material, the particle beam, the experimental technique, and the damage calculations. Reference should be made to other ASTM standards, especially Practice E 521. Procedures are described that are applicable to creep and creep rupture tests made in tension and torsion test modes. 1.2 The word simulation is used here in a broad sense to imply an approximation of the relevant neutron irradiation environment. The degree of conformity can range from poor to nearly exact. The intent is to produce a correspondence between one or more aspects of the neutron and charged particle irradiations such that fundamental relationships are established between irradiation or material parameters and the material respons...

  16. Quasi-particle properties from tunneling in the v = 5/2 fractional quantum Hall state.

    Science.gov (United States)

    Radu, Iuliana P; Miller, J B; Marcus, C M; Kastner, M A; Pfeiffer, L N; West, K W

    2008-05-16

    Quasi-particles with fractional charge and statistics, as well as modified Coulomb interactions, exist in a two-dimensional electron system in the fractional quantum Hall (FQH) regime. Theoretical models of the FQH state at filling fraction v = 5/2 make the further prediction that the wave function can encode the interchange of two quasi-particles, making this state relevant for topological quantum computing. We show that bias-dependent tunneling across a narrow constriction at v = 5/2 exhibits temperature scaling and, from fits to the theoretical scaling form, extract values for the effective charge and the interaction parameter of the quasi-particles. Ranges of values obtained are consistent with those predicted by certain models of the 5/2 state.

  17. Influence of hard particle addition and chemical interdiffusion on the properties of hot extruded tool steel compounds

    International Nuclear Information System (INIS)

    Silva, P.A.; Weber, S.; Inden, G.; Pyzalla, A.R.

    2009-01-01

    Low alloyed steel bars were co-extruded with pre-sintered tool steel powders with the addition of tungsten carbides (W 2 C/WC) as hard particles. During the hot extrusion process of these massive and powdery materials, an extrudate is formed consisting of a completely densified wear resistant coating layer and a bulk steel bar as the tough substrate core. This work combines experimental measurements (EPMA) and diffusion calculations (DICTRA TM ) to investigate the effect of hard particle addition and its dissolution, as well as the formation of M 6 C carbides on the properties of two different PM tool steel coatings hot extruded with a 1.2714 steel bar. A carburization effect resulting from the W 2 C hard particles is responsible for an increase of the 1.2344 steel matrix hardness. The mechanical properties of the interface region between coating matrix and substrate are influenced by chemical interdiffusion of carbon and other alloying elements occurring during heat treatment.

  18. Structural, magnetic, and electrical properties of Gd-doped BiFeO3 nanoparticles with reduced particle size

    International Nuclear Information System (INIS)

    Lotey, Gurmeet Singh; Verma, N. K.

    2012-01-01

    Pure and Gd-doped BiFeO 3 nanoparticles have been synthesized by sol–gel method. The significant effects of size and Gd-doping on structural, electrical, and magnetic properties have been investigated. X-ray diffraction study reveals that the pure BiFeO 3 nanoparticles possess rhombohedral structure, but with 10% Gd-doping complete structural transformation from rhombohedral to orthorhombic has been observed. The particle size of pure and Gd-doped BiFeO 3 nanoparticles, calculated using Transmission electron microscopy, has been found to be in the range 25–15 nm. Pure and Gd-doped BiFeO 3 nanoparticles show ferromagnetic character, and the magnetization increases with decrease in particle size and increase in doping concentration. Scanning electron microscopy study reveals that grain size decreases with increase in Gd concentration. Well-saturated polarization versus electric field loop is observed for the doped samples. Leakage current density decreases by four orders by doping Gd in BiFeO 3 . The incorporation of Gd in BiFeO 3 enhances spin as well as electric polarization at room temperature. The possible origin of enhancement in these properties has been explained on the basis of dopant and its concentration, phase purity, small particle, and grain size.

  19. Effect of shot peening using ultra-fine particles on fatigue properties of 5056 aluminum alloy under rotating bending

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Shoichi, E-mail: kikuchi@mech.kobe-u.ac.jp [Department of Mechanical Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501 (Japan); Nakamura, Yuki [Department of Mechanical Engineering, National Institute of Technology, Toyota College, 2-1 Eisei-cho, Toyota-shi, Aichi 471-8525 (Japan); Nambu, Koichiro [Department of Mechanical Engineering, National Institute of Technology, Suzuka College, Shiroko-cho, Suzuka-shi, Mie 510-0294 (Japan); Ando, Masafumi [Innovation Team, IKK SHOT Co. Ltd., 412-4, Nunowari, Minami-Shibata-machi, Tokai-shi, Aichi 476-0001 (Japan)

    2016-01-15

    Shot peening using particles 10 μm in diameter (ultra-fine particle peening: Ultra-FPP) was introduced to improve the fatigue properties of 5056 aluminum alloy. The surface microstructures of the Ultra-FPP treated specimens were characterized using a micro-Vickers hardness tester, scanning electron microscopy (SEM), X-ray diffraction (XRD), non-contact scanning white light interferometry, and electron backscatter diffraction (EBSD). The Ultra-FPP treated specimen had higher hardness than the conventional FPP treated specimen with a short nozzle distance due to the high velocity of the ultra-fine particles. Furthermore, the surface hardness of the Ultra-FPP treated specimen tended to increase as the peening time decreased. Fatigue tests were performed in air at room temperature using a cantilever-type rotating bending fatigue testing machine. It was found that the fatigue life of the Ultra-FPP treated specimen tended to increase with decreasing peening time. Mainly, the Ultra-FPP improved the fatigue properties of 5056 aluminum alloy in the very high cycle regime of more than 10{sup 7} cycles compared with the un-peened specimens. This is because the release of the compressive residual stress is small during fatigue tests at low stress amplitudes.

  20. Properties of copper matrix reinforced with nano- and micro-sized Al2O3 particles

    International Nuclear Information System (INIS)

    Rajkovic, Viseslava; Bozic, Dusan; Jovanovic, Milan T.

    2008-01-01

    The mixture of electrolytic copper powder with 5 wt.% of commercial Al 2 O 3 powder (average particle size: 15 and 0.75 μm, respectively) and the inert gas atomized prealloyed copper powder (average particle size: 30 μm) containing 2.5 wt.% aluminum were separately milled in air up to 20 h in the planetary ball mill. During milling aluminum in the prealloyed copper powders was oxidized in situ by internal oxidation with oxygen from the air forming very fine nano-sized Al 2 O 3 particles. The internal oxidation of 2.5 wt.% aluminum generated 4.7 wt.% of Al 2 O 3 in the copper matrix. Powders and compacts were characterized by light and scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray diffraction analysis. Microhardness and electrical conductivity were also included in measurements. The microhardness of Cu-2.5 wt.% Al compacts was 3.6 times higher than that of compacts processed from electrolytic copper powder. This increase in microhardness is a consequence of a fine dispersion of Al 2 O 3 particles and refined grain structure. The average values of electrical conductivity of compacts processed from Cu-5 wt.% Al 2 O 3 and Cu-2.5 wt.% Al powders previously milled for 20 h and were 88% and 70% IACS, respectively, which is a rather significant increase if compared with values of 60% and 23% IACS of compacts processed from as-received and non-milled powders. The microhardness of 20-h milled compacts decreases with the heat treatment at 800 deg. C. Due to the effect of nano-sized Al 2 O 3 particles Cu-2.5 wt.% Al compacts show lower decrease in microhardness. The results are discussed in terms of the effect of Al 2 O 3 particle size and fine grain structure on the reinforcing of the copper matrix

  1. Dengue virus-like particles mimic the antigenic properties of the infectious dengue virus envelope.

    Science.gov (United States)

    Metz, Stefan W; Thomas, Ashlie; White, Laura; Stoops, Mark; Corten, Markus; Hannemann, Holger; de Silva, Aravinda M

    2018-04-02

    The 4 dengue serotypes (DENV) are mosquito-borne pathogens that are associated with severe hemorrhagic disease. DENV particles have a lipid bilayer envelope that anchors two membrane glycoproteins prM and E. Two E-protein monomers form head-to-tail homodimers and three E-dimers align to form "rafts" that cover the viral surface. Some human antibodies that strongly neutralize DENV bind to quaternary structure epitopes displayed on E protein dimers or higher order structures forming the infectious virus. Expression of prM and E in cell culture leads to the formation of DENV virus-like particles (VLPs) which are smaller than wildtype virus particles and replication defective due to the absence of a viral genome. There is no data available that describes the antigenic landscape on the surface of flavivirus VLPs in comparison to the better studied infectious virion. A large panel of well characterized antibodies that recognize epitope of ranging complexity were used in biochemical analytics to obtain a comparative antigenic surface view of VLPs in respect to virus particles. DENV patient serum depletions were performed the show the potential of VLPs in serological diagnostics. VLPs were confirmed to be heterogeneous in size morphology and maturation state. Yet, we show that many highly conformational and quaternary structure-dependent antibody epitopes found on virus particles are efficiently displayed on DENV1-4 VLP surfaces as well. Additionally, DENV VLPs can efficiently be used as antigens to deplete DENV patient sera from serotype specific antibody populations. This study aids in further understanding epitopic landscape of DENV VLPs and presents a comparative antigenic surface view of VLPs in respect to virus particles. We propose the use VLPs as a safe and practical alternative to infectious virus as a vaccine and diagnostic antigen.

  2. The effect of alumina particles on the microstructural and mechanical properties of copper foams fabricated by space-holder method

    Science.gov (United States)

    Salvo, C.; Aguilar, C.; Lascano, S.; Pérez, L.; López, M.; Mangalaraja, R. V.

    2018-05-01

    The copper foam is an interesting field of research because of its several advantages as an engineering material. Powder metallurgy presents an alternative route to obtain a porous structure with high strength to weight ratio and functional properties. The viability of processing copper foam separately with two different space-holders such as ammonium hydrogen carbonate (NH4HCO3) and sodium chloride (NaCl) of 50 vol% was studied. The green compacts obtained under 200 MPa were sintered at different cycles for the complete removal of space-holder. The sintered foams were characterized by optical microscopy (OM), scanning electron microscopy (SEM) and uniaxial testing machine (UTM) to study their structural features and compressive strength, respectively. The results showed that NaCl particles were the best alternative to obtain a porous structure, hence two different sizes (1 and 0.01 μm) of alumina (Al2O3) particles with 2, 4 and 6 vol% were used to fabricate copper foams. As a result, a bimodal structure consisting of macro and micropores with a highly interconnected porosity was achieved. In addition, the smaller size alumina particles promoted a higher density of pores, however, the compressive strength was reduced for the higher volume fraction of alumina particles.

  3. The effect of calcium on the composition and physical properties of whey protein particles prepared using emulsification.

    Science.gov (United States)

    Westerik, Nieke; Scholten, Elke; Corredig, Milena

    2015-06-15

    Protein microparticles were formed through emulsification of 25% (w/w) whey protein isolate (WPI) solutions containing various concentrations of calcium (0.0-400.0mM) in an oil phase stabilized by polyglycerol polyricinoleate (PGPR). The emulsions were heated (at 80°C) and the microparticles subsequently re-dispersed in an aqueous phase. Light microscopy and scanning electron microscopy (SEM) images revealed that control particles and those prepared with 7.4mM calcium were spherical and smooth. Particles prepared with 15.0mM calcium gained an irregular, cauliflower-like structure, and at concentrations larger than 30.0mM, shells formed and the particles were no longer spherical. These results describe, for the first time, the potential of modulating the properties of dense whey protein particles by using calcium, and may be used as structuring agents for the design of functional food matrices with increased protein and calcium content. Copyright © 2015. Published by Elsevier Ltd.

  4. An experimental study of the dynamic properties of nanoparticle colloids with identical magnetization but different particle size

    International Nuclear Information System (INIS)

    Fannin, P.C.; Marin, C.N.; Raj, K.; Couper, C.; Barvinschi, P.

    2012-01-01

    Measurements of the frequency dependent complex magnetic susceptibility, χ(ω)=χ′(ω)−iχ″(ω), have been used to determine the dynamic properties of three specially prepared 400 G (0.04 T) magnetic fluids. The samples, denoted by sample 1, sample 2 and sample 3, consisted of magnetite particles of mean diameter 6.4 nm, 7.5 nm and 9 nm respectively and were identical in terms of carrier liquid, surfactant and particle material. From polarized ferromagnetic measurements, the anisotropy field, H A , the Landau–Lifshitz damping parameter, α, and the precessional decay time, τ 0 of the particles were determined. The results show that the H A value for sample 3 was almost twice that of sample 1 and 2, thus confirming that the smaller the particle size, the lower the value of H A . The damping parameter, α, was found to be 0.174 (for sample 1), 0.18 (for sample 2) and 0.16 (for sample 3). The values determined for the precessional decay time, τ 0 were 1.197×10 −9 s, 1.157×10 −9 s and 0.789×10 −9 s, for samples 1, 2 and 3 respectively.

  5. Effect of particle treatment and adhesive type on physical, mechanical, and durability properties of particleboard made from Sorghum Bagasse

    Science.gov (United States)

    Heri Iswanto, Apri; Supriyanto; Fatriasari, Widya; Susilowati, Arida

    2018-03-01

    Refers to chemical content of sweet sorghum stalk especially for Numbu varian, sorghum bagasse issuitable for materials of particleboard. The objective of the experiment was to evaluate of particle treatment on physichal, mechanical, and durability properties of particleboard made from sorghum bagasse. For particle treatment, Sorghum bagasse immersed in cold water and hot water for 24 and 1 hours respectively. Particleboards were produced in size 25 by 25 cm2 with thickness and density target of 0.8 cm and 0.7 g/cm3. Amount of 10% Urea formaldehyde (UF) and 7% isocyanat (MDI) adhesive level used for manufacturing of board. Particle and adhesive were blended with rotary blending. Afterward, it was placed into mat former with size of 25 by 25 cm2. Mat was pressed by hot press machine. The pressing was conducted on 130°C temperature for UF resin and 160°C for MDI resin, pressure of 25 kg/cm2 and pressing time for 10 minutes. The results showed that particle soaking in hot water produced of lower thickness swelling compared to untreated board. Similar trend also occuron particleboard whichwas bonded with MDI resin. MDI as exterior adhesive resulted good performance in dimensional stability of sorghum bagasse particleboard. For UF bonded particleboard, immersing in hot water resulted in the low MOR, MOE and IB parameter. It’s contrary with MDI bonded particleboard.

  6. Influence of particle size and chemistry on the cloud nucleating properties of aerosols

    Directory of Open Access Journals (Sweden)

    P. K. Quinn

    2008-02-01

    Full Text Available The ability of an aerosol particle to act as a cloud condensation nuclei (CCN is a function of the size of the particle, its composition and mixing state, and the supersaturation of the cloud. In-situ data from field studies provide a means to assess the relative importance of these parameters. During the 2006 Texas Air Quality – Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS-GoMACCS, the NOAA RV Ronald H. Brown encountered a wide variety of aerosol types ranging from marine near the Florida panhandle to urban and industrial in the Houston-Galveston area. These varied sources provided an opportunity to investigate the role of aerosol sources and chemistry in the potential activation of particles to form cloud droplets. Measurements were made of CCN concentrations, aerosol chemical composition in the size range relevant for particle activation in warm clouds, and aerosol size distributions. Variability in aerosol composition was parameterized by the mass fraction of Hydrocarbon-like Organic Aerosol (HOA for particle diameters less than 200 nm (vacuum aerodynamic. The HOA mass fraction in this size range was lowest for marine aerosol and highest for aerosol sampled close to anthropogenic sources. Combining all data from the experiment reveals that composition (defined by HOA mass fraction explains 40% of the variance in the critical diameter for particle activation at the instrumental supersaturation (S of 0.44%. Correlations between HOA mass fraction and aerosol mean diameter show that these two parameters are essentially independent of one another for this data set. We conclude that, based on the variability of the HOA mass fraction observed during TexAQS-GoMACCS, variability in particle composition played a significant role in determining the fraction of particles that could activate to form cloud droplets. Using a simple model based on Köhler theory and the assumption that HOA is insoluble, we estimate the

  7. Magnetic properties of iron catalyst particles in HiPco single wall carbon nanotubes

    Czech Academy of Sciences Publication Activity Database

    Bittová, Barbara; Poltierová Vejpravová, Jana; Kalbáč, Martin; Burianová, Simona; Mantlíková, A.; Daniš, S.; Doyle, S.

    2011-01-01

    Roč. 115, č. 35 (2011), s. 17303-17309 ISSN 1932-7447 R&D Projects: GA ČR GAP204/10/1677 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40400503 Keywords : metal catalyst particles * carbon nanotubes * superparamagnet * core - shell model * inter-particle interactions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.805, year: 2011 http://pubs.acs.org/doi/abs/10.1021/jp203365g

  8. Investigation of doping and particle size effect on structural, magnetic and magnetoresistance properties of manganites

    Directory of Open Access Journals (Sweden)

    M. Hakimi

    2008-06-01

    Full Text Available  In this paper after introduction of manganites, we have studied the effect of particle size and doping on structural, magnetic and magnetoresistance of LSMO manganite samples. The magnetoresistance measurements show that, by decreasing the particle size LFMR increases. Also the results show that the LFMR increases at low doping levels and decreases at high doping levels. The spin dependent tunneling and scattering at the grain boundaries is the origin of increasing the LFMR at low doping levels. Also the substitution of impurity ions at Mn sites and subsequently weaking of double exchange is responsible for decreasing of LFMR at high doping level.

  9. Theoretical and Numerical Investigation of Polymer-Particle Nanocomposites and their Effective Materials Properties

    National Research Council Canada - National Science Library

    Wang, Qi

    2008-01-01

    .... The project aimed to study the mesoscopic structure formation during flow processing and the corresponding rheological consequence leading to characterization of material properties in solid states...

  10. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    Directory of Open Access Journals (Sweden)

    A. Petzold

    2008-05-01

    Full Text Available Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel−1 by number for non-volatile particles and 174±43 mg (kg fuel−1 by mass for Black Carbon (BC. Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dp<0.3 μm, showing a bi-modal structure. The combustion particle mode is centred at modal diameters of 0.05 μm for raw emissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

  11. Microstructure and property of WC particles ceramic-metal composite coatings by laser surface cladding

    International Nuclear Information System (INIS)

    Zeng Xiaoyan; Zhu Beidi; Tao Zengyi; Yang Shuguo; Cui Kun

    1993-01-01

    Ceramic-metal is widely used as a kind of good hardfacing material. The coarse WC particles ceramic-metal composite coatings with WC density of 67% it weight and the thickness of 1.6-2.0 mm have been cladded on 20Ni 4 Mo steel surface by a 2kw CO 2 laser. The sintered WC particles with the size of 600-1,000 μm are chosen as the main strengthening phase, Ni-base self-flux alloy as the binder in the composite coatings. The microstructure and micro-hardness of both WC particles and binder are analyzed. The rigid ball indention with acoustic emission technique is used to evaluate the brittleness of the coating. Finally, the abrasive wear resistance of the coatings are tested, Besides, the coatings with the same ratio and size of WC particles within low carbon steel tube were cladded on 20Ni 4 Mo steel by atomic hydrogen welding technique and analyzed by the same ways their result are compared

  12. Physical properties and microstructure of Ti(CN)-based cermets with different WC particle size

    International Nuclear Information System (INIS)

    Deng, Ying; Deng, Ling; Xiong, Xiang; Ye, J.W.; Li, P.P.

    2014-01-01

    Ti(CN)-based cermets with different WC particle sizes from 0.2 to 4 μm were prepared at 1450 °C with 2 MPa Air pressure. The microstructure of cermets was investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), Transmission electron microscope (TEM). The results showed that all the cermets with different WC particle sizes have a typical “core–rim” structure. With the increase of WC powder sizes, the frequency and portion of Ti(C 0.7 N 0.3 ) cores and rim are somewhat decreased while the portion of white core is increased, due to the relative dissolution rate decreasing. In addition, the fracture mode of Ti(C,N) based cermets is a mixture of trans-granular (primary) and inter-granular (subordinate) fracture. The TRS (about 1850 MPa) of the cermets fluctuate slightly with the WC particle sizes from 0.2 to 1.0 μm, but decrease evidently with WC particle sizes up to 2 μm

  13. Particle models for discrete element modeling of bulk grain properties of wheat kernels

    Science.gov (United States)

    Recent research has shown the potential of discrete element method (DEM) in simulating grain flow in bulk handling systems. Research has also revealed that simulation of grain flow with DEM requires establishment of appropriate particle models for each grain type. This research completes the three-p...

  14. Basic Evidence and Properties of Single-Particle States in Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Cindro, N. [Institute ' ' Rudjer Boskovic' ' , Zagreb, Yugoslavia (Croatia)

    1970-07-15

    1. Introduction: the shell-model orbitals; 2. Information about single-particle orbitals: a critical evaluation; 3. Experimental evidence: 3.1. The lead region; 3.2. The calcium region; 3.3. Nuclei far from closed shells; 4. Conclusion. (author)

  15. Laser melt injection of ceramic particles in metals : Processing, microstructure and properties

    NARCIS (Netherlands)

    Ocelík, V.; De Hosson, J.Th.M.

    2010-01-01

    The objective of this paper is to present an overview of the possibilities of the laser melt injection (LMI) methodology to enhance the surface of light-weighted metals by adding hard ceramic particles in the top layer, with the aim to enhance the wear resistance and to increase the hardness. In

  16. Nuclear shape transitions and some properties of aligned-particle configurations at high spin

    International Nuclear Information System (INIS)

    Koo, T.L.; Chowdhury, P.; Emling, H.

    1982-01-01

    Two topics are addressed in this paper. First, we discuss the variation of shapes with spin and neutron number for nuclei in the N approx. = 88 transitional region. Second, we present comments on the feeding times of very high spin single-particle yrast states

  17. HMW-GS affect the properties of glutenin particles in GMP and thus flour quality

    NARCIS (Netherlands)

    Don, C.; Mann, G.; Bekes, F.; Hamer, R.J.

    2006-01-01

    Using a unique set of deletion lines, (Olympic×Gabo, varying in high molecular weight glutenin subunit (HMW-GS) composition, but with the same genetic background) it was shown that the presence of glutenin particles in glutenin macropolymer (GMP) is directly related to the presence of certain

  18. Phase coexistence in thin liquid films stabilized by colloidal particles: equilibrium and non-equilibrium properties

    International Nuclear Information System (INIS)

    Blawzdziewicz, J.; Wajnryb, E.

    2005-01-01

    Phase equilibria between regions of different thickness in thin liquid films stabilized by colloidal particles are investigated using a quasi-two-dimensional thermodynamic formalism. Appropriate equilibrium conditions for the film tension, normal pressure, and chemical potential of the particles in the film are formulated, and it is shown that the relaxation of these parameters occurs consecutively on three distinct time scales. Film stratification is described quantitatively for a hard-sphere suspension using a Monte-Carlo method to evaluate thermodynamic equations of state. Coexisting phases are determined for systems in constrained- and full-equilibrium states that correspond to different stages of film relaxation. We also evaluated the effective viscosity coefficients for two-dimensional compressional and shear flows of a film and the self and collective mobility coefficients of the stabilizing particles. The hydrodynamic calculations were performed using a multiple-reflection representation of Stokes flow between two free surfaces. In this approach, the particle-laden film is equivalent to a periodic system of spheres with a unit cell that is much smaller in the transverse direction than in the lateral direction. (author)

  19. Composite polypyrrole-containing particles and electrical properties of thin films prepared therefrom

    Czech Academy of Sciences Publication Activity Database

    Lu, Y.; Pich, A.; Adler, H.-J.; Wang, G.; Rais, David; Nešpůrek, Stanislav

    2008-01-01

    Roč. 49, č. 23 (2008), s. 5002-5012 ISSN 0032-3861 R&D Projects: GA AV ČR KAN400720701; GA MŠk OC 138 Institutional research plan: CEZ:AV0Z40500505 Keywords : core-shell particles * polypyrrole * electrical conductivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.331, year: 2008

  20. Effect of round particles on shear strength properties of railway ballast

    CSIR Research Space (South Africa)

    Mvelase, GM

    2016-07-01

    Full Text Available particles. Sedimentary Petrology, 11, pp. 64-72, 1941. [11] Folk, R.L., Student operator error in determining of roundness, sphericity and grain size. Sedimentary Petrology, 25, pp. 297-301, 1955. [12] Janoo, V.C., Quantification of shape, angularity...

  1. Quasi-particle properties in a quasi-two-dimensional electron liquid

    Indian Academy of Sciences (India)

    effects are incorporated into the local-field factors that describe the charge and spin correla- ... dient of which is the quasi-particle concept and its interactions. .... factors. Note that we have approximated the local-field factors by their static, frequency-independent limits. Quite generally, once the QP self-energy is known, the ...

  2. Physical Properties and Lung Deposition of Particles Emitted from Five Major Indoor Sources.

    Czech Academy of Sciences Publication Activity Database

    Tuan, V.Vu.; Ondráček, Jakub; Ždímal, Vladimír; Schwarz, Jaroslav; Delgado-Saborit, J.M.; Harrison, R. M.

    2016-01-01

    Roč. 10, č. 1 (2016), s. 1-14 ISSN 1873-9318 EU Projects: European Commission(XE) 315760 - HEXACOMM Institutional support: RVO:67985858 Keywords : indoor sources * particle size * hygroscopic growth Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.184, year: 2016

  3. [Light scattering extinction properties of atmospheric particle and pollution characteristics in hazy weather in Hangzhou].

    Science.gov (United States)

    Xu, Chang; Ye, Hui; Shen, Jian-Dong; Sun, Hong-Liang; Hong, Sheng-Mao; Jiao, Li; Huang, Kan

    2014-12-01

    In order to evaluate the influence of particle scattering on visibility, light scattering coefficient, particle concentrations and meteorological factor were simultaneously monitored from July 2011 to June 2012 in Hangzhou. Daily scattering coefficients ranged from 108.4 to 1 098.1 Mm(-1), with an annual average concentration of 428.6 Mm(-1) ± 200.2 Mm(-1). Seasonal variation of scattering coefficients was significant, with the highest concentrations observed in autumn and winter and the lowest in summer. It was found there were two peaks for the average diurnal variations of the scattering coefficient, which could be observed at 08:00 and 21:00. The scattering efficiencies of PM2.5 and PM10 were 7.6 m2 x g(-1) and 4.4 m2 x g(-1), respectively. The particle scattering was about 90.2 percent of the total light extinction. The scattering coefficients were 684.4 Mm(-1) ± 218.1 Mm(-1) and 1 095.4 Mm(-1) ± 397.7 Mm(-1) in hazy and heavy hazy days, respectively, which were 2.6 and 4.2 times as high as in non-hazy weather, indicating that particle scattering is the main factor for visibility degradation and the occurrence of hazy weather in Hangzhou.

  4. Dynamical properties for the problem of a particle in an electric field of wave packet: Low velocity and relativistic approach

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Diego F.M., E-mail: diegofregolente@gmail.com [Institute for Multiscale Simulations, Friedrich-Alexander Universität, D-91052, Erlangen (Germany); Leonel, Edson D., E-mail: edleonel@rc.unesp.br [Departamento de Estatística, Matemática Aplicada e Computação, UNESP, Univ. Estadual Paulista, Av. 24A, 1515, Bela Vista, 13506-900, Rio Claro, SP (Brazil); Departamento de Física, UNESP, Univ. Estadual Paulista, Av. 24A, 1515, 13506-900, Rio Claro, SP (Brazil)

    2012-11-01

    We study some dynamical properties for the problem of a charged particle in an electric field considering both the low velocity and relativistic cases. The dynamics for both approaches is described in terms of a two-dimensional and nonlinear mapping. The structure of the phase spaces is mixed and we introduce a hole in the chaotic sea to let the particles to escape. By changing the size of the hole we show that the survival probability decays exponentially for both cases. Additionally, we show for the relativistic dynamics, that the introduction of dissipation changes the mixed phase space and attractors appear. We study the parameter space by using the Lyapunov exponent and the average energy over the orbit and show that the system has a very rich structure with infinite family of self-similar shrimp shaped embedded in a chaotic region.

  5. 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.

  6. Three-dimensional labeling program for elucidation of the geometric properties of biological particles in three-dimensional space.

    Science.gov (United States)

    Nomura, A; Yamazaki, Y; Tsuji, T; Kawasaki, Y; Tanaka, S

    1996-09-15

    For all biological particles such as cells or cellular organelles, there are three-dimensional coordinates representing the centroid or center of gravity. These coordinates and other numerical parameters such as volume, fluorescence intensity, surface area, and shape are referred to in this paper as geometric properties, which may provide critical information for the clarification of in situ mechanisms of molecular and cellular functions in living organisms. We have established a method for the elucidation of these properties, designated the three-dimensional labeling program (3DLP). Algorithms of 3DLP are so simple that this method can be carried out through the use of software combinations in image analysis on a personal computer. To evaluate 3DLP, it was applied to a 32-cell-stage sea urchin embryo, double stained with FITC for cellular protein of blastomeres and propidium iodide for nuclear DNA. A stack of optical serial section images was obtained by confocal laser scanning microscopy. The method was found effective for determining geometric properties and should prove applicable to the study of many different kinds of biological particles in three-dimensional space.

  7. 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

  8. Influence of co-electrodeposited Gold particles on the electrocatalytic properties of CoHCF thin films

    International Nuclear Information System (INIS)

    Kumar, Alam Venugopal Narendra; Joseph, James

    2014-01-01

    The electrochemical modification of solid electrodes with metal hexacyanoferrate thin films for enhancing the interfacial properties has created interest for over the past three decades. The preparation of Prussian blue (PB) Au nano composites for the enhancement in the electrocatalytic properties of PB on glassy carbon electrode has been reported by us. The incorporation of Au nano particles in Cobalt hexacyanoferrate (CoHCF) films on Glassy carbon by co-electrodeposition is expected to benefit its interfacial electron transfer properties. The present work describes the effect on the interfacial properties by incorporated Au particles in CoHCF (CoHCF(Au)) modified electrodes. The CoHCF(Au) modified electrodes were characterized by UV-Vis spectrophotometry, Cyclic Voltammetry, AC Impedance, FE-SEM etc., Influence on the electrocatalytic properties of CoHCF(Au) films have been explored by performing two important reactions i) Hydrazine elecrtro-oxidation ii) Oxygen evolution reaction. Our results reveal that CoHCF(Au) modified GC electrode perform better in terms of charge transport in the redox film and also for the electrooxidation of hydrazine in comparision with simple CoHCF modified electrodes. By using the current-transient technique (chrono method i vs t curve) the hydrazine diffusion coefficient (D 0 ) were calculated. Diffusion coefficient of hydrazine was approximately three times higher on CoHCF(Au) electrode, 9.5 × 10 −5 cm 2 s −1 compared with simple CoHCF modified electrode, 3.3× 10 −5 cm 2 s −1 . Similarly, we also discuss results which reveal that CoHCF(Au) electrodes enhances electrocatalytic activity in splitting water to oxygen in 0.1 M NaOH solution compared to simple CoHCF and Au deposited on GC electrodes

  9. Comparative evaluation of particle properties, formation of reactive oxygen species and genotoxic potential of tungsten carbide based nanoparticles in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kuehnel, Dana, E-mail: dana.kuehnel@ufz.de [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Scheffler, Katja [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Department of Cell Techniques and Applied Stem Cell Biology, University of Leipzig, Deutscher Platz 5, 04103 Leipzig (Germany); Wellner, Peggy [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Meissner, Tobias; Potthoff, Annegret [Fraunhofer-Institute for Ceramic Technologies and Systems (IKTS), Winterbergstr. 28, 01277 Dresden (Germany); Busch, Wibke [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Springer, Armin [Centre for Translational Bone, Cartilage and Soft Tissue Research, University Hospital Carl Gustav Carus, Technical University Dresden, Fetscherstrasse 74, 01307 Dresden (Germany); Schirmer, Kristin [Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf (Switzerland); EPF Lausanne, School of Architecture, Civil and Environmental Engineering, 1015 Lausanne (Switzerland); ETH Zuerich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zuerich (Switzerland)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Assessment of toxic potential of tungsten carbide-based nanoparticles. Black-Right-Pointing-Pointer Evaluation of ROS and micronuclei induction of three hard metal nanomaterials. Black-Right-Pointing-Pointer Dependency of observed toxic effects on the materials physical-chemical properties. Black-Right-Pointing-Pointer Differences in several particle properties seem to modulate the biological response. - Abstract: Tungsten carbide (WC) and cobalt (Co) are constituents of hard metals and are used for the production of extremely hard tools. Previous studies have identified greater cytotoxic potential of WC-based nanoparticles if particles contained Co. The aim of this study was to investigate whether the formation of reactive oxygen species (ROS) and micronuclei would help explain the impact on cultured mammalian cells by three different tungsten-based nanoparticles (WC{sub S}, WC{sub L}, WC{sub L}-Co (S: small; L: large)). The selection of particles allowed us to study the influence of particle properties, e.g. surface area, and the presence of Co on the toxicological results. WC{sub S} and WC{sub L}/WC{sub L}-Co differed in their crystalline structure and surface area, whereas WC{sub S}/WC{sub L} and WC{sub L}-Co differed in their cobalt content. WC{sub L} and WC{sub L}-Co showed neither a genotoxic potential nor ROS induction. Contrary to that, WC{sub S} nanoparticles induced the formation of both ROS and micronuclei. CoCl{sub 2} was tested in relevant concentrations and induced no ROS formation, but increased the rate of micronuclei at concentrations exceeding those present in WC{sub L}-Co. In conclusion, ROS and micronuclei formation could not be associated with the presence of Co in the WC-based particles. The contrasting responses elicited by WC{sub S} vs. WC{sub L} appear to be due to large differences in crystalline structure.

  10. Study of Thermal Properties, Turbidity, Effective Factors on Particle Size and Oscillatory Rheology of Pectin-Caseinate Biopolymer Nanocomplexes

    Directory of Open Access Journals (Sweden)

    Sajedeh Bahrani

    2013-02-01

    Full Text Available The biopolymer-based nanocomplexes are a group of nanocapsules that are used for encapsulation and control delivery of nutraceuticals. They are formed by binding of proteins and polysaccharides. In this study, complex formation between pectin and sodium caseinate was taken place by addition of pectin solutions(0.2, 0.45 and 0.7 % w/v into the caseinate solutions (0.5, 1 and 1.5 % w/v and adjusted their pH below isoelecteric point of sodium caseinate. The effect of various factors such as biopolymer concentration, salt concentration, temperature and time of ultrasound on the properties of pectin-casein nanocomplexes was investigated. Differential scanning calorimetry (DSC and particle size analyzer were used for study of complex formation and particle size determination, respectively. The results of DSC and turbidimetry showed complex formation between the pectin and casein at pH below 5 and the results of particle size showed formation of stable dispersion with a minimum size of 86 nm at pH 4.1, caseinate of 1 % w/v and pectin 0.45 % w/v concentration. The ultrasound for more than 1 min reduced particle size and addition of salt at high and low concentrations had different effects on the stability of the colloidal system. The lowering of temperature from 21 to 4°C resulted in smaller particle size of nanocomplexes. The oscillatory rheological results showed that with increasing pectin concentration, viscoelastic moduli were increased and loss moduli were higher than storage modulus.

  11. Effect of the structure of Pt-Ru/C particles on COad monolayer vibrational properties and electrooxidation kinetics

    International Nuclear Information System (INIS)

    Maillard, Frederic; Bonnefont, Antoine; Chatenet, Marian; Guetaz, Laure; Doisneau-Cottignies, Beatrice; Roussel, Herve; Stimming, Ulrich

    2007-01-01

    In this paper, we combined FTIR spectroscopy and CO ad stripping voltammetry to investigate CO ad adsorption and electrooxidation on Pt-Ru/C nanoparticles. The Pt:Ru elemental composition and the metal loading were determined by ICP-AES. The X-ray diffraction patterns of the Pt-Ru/C indicated formation of a Pt-Ru (fcc) alloy. HREM images revealed an increase in the fraction of agglomerated Pt-Ru/C particles with increasing the metal loading and showed that agglomerated Pt-Ru/C nanoparticles present structural defects such as twins or grain boundaries. In addition, isolated Pt-Ru/C nanoparticles have similar mean particle size (ca. 2.5 nm) and particle size distributions whatever the metal loading. Therefore, we could determine precisely the effect of particle agglomeration on the CO ad vibrational properties and electrooxidation kinetics. FTIR measurements revealed a main CO ad stretching band at ca. ν-bar CO L =2030cm -1 , which we ascribed to a-top CO ad on Pt domains electronically modified by the presence of Ru. As the metal loading increased, the position of this band was blue shifted by ca. 5 cm -1 and a shoulder around 2005 cm -1 developed, which was ascribed to a-top CO ad on Ru domains. The reason for this was suggested to be the increasing size of Ru domains on agglomerated Pt-Ru/C particles, which lifts dipole-dipole coupling and allows two vibrational features to be observed (CO ad /Ru, CO ad /Pt). This is evidence that FTIR spectroscopy can be used to probe small chemical fluctuations of the Pt-Ru/C surface. Finally, we comment on the CO ad electrooxidation kinetics. We observed that CO ad was converted more easily into CO 2 as the metal loading, i.e. the fraction of agglomerated Pt-Ru/C nanoparticles, increased

  12. Influence of template/functional monomer/cross‐linking monomer ratio on particle size and binding properties of molecularly imprinted nanoparticles

    DEFF Research Database (Denmark)

    Yoshimatsu, Keiichi; Yamazaki, Tomohiko; Chronakis, Ioannis S.

    2012-01-01

    A series of molecularly imprinted polymer nanoparticles have been synthesized employing various template/functional monomer/crosslinking monomer ratio and characterized in detail to elucidate the correlation between the synthetic conditions used and the properties (e.g., particle size and templat...... tuning of particle size and binding properties are required to fit practical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012...

  13. Effect of two-step aging on spatial distribution of γ-phase particles and mechanical properties of Ni-14at.% Al single crystals

    International Nuclear Information System (INIS)

    Tyapkin, Yu.D.; Travina, N.T.; Ugarova, E.V.

    1977-01-01

    Electron microscope images were processed by statistical methods to investigate the space distribution of particles of the γ'-phase (formation of ''quasiperiodic micro-lattices'') after various conditions of single- and double-stage aging of the Ni-14 at.% Al alloy. Mechanical properties in uniaxial tension of single crystals were studied. Parameters of the space distribution of particles have been correlated with the mechanical properties

  14. Analysis of the structure, particle morphology and photoluminescent properties of ZnS:Mn2+ nanoparticulate phosphors

    CSIR Research Space (South Africa)

    Raleaooa, PV

    2018-01-01

    Full Text Available stream_source_info Raleaooa_20160_2018.pdf.txt stream_content_type text/plain stream_size 1286 Content-Encoding UTF-8 stream_name Raleaooa_20160_2018.pdf.txt Content-Type text/plain; charset=UTF-8 Optik - International... journal for Light and Electron Optics Analysis of the structure, particle morphology and photoluminescent properties of ZnS:Mn2+ nanoparticulate phosphors Raleaooa PV Roodt A Mhlongo GH Motaung DE Ntwaeaborwa OM ABSTRACT: The structure...

  15. Critical solvent properties affecting the particle formation process and characteristics of celecoxib-loaded PLGA microparticles via spray-drying

    DEFF Research Database (Denmark)

    Wan, Feng; Bohr, Adam; Maltesen, Morten Jonas

    2013-01-01

    ) microparticles prepared by spray-drying. METHODS: Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties...... and drug release profile. The evaporation profiles of the feed solutions were investigated using thermogravimetric analysis (TGA). RESULTS: Spherical PLGA microparticles were obtained, irrespectively of the solvent composition. The particle size and surface chemistry were highly dependent on the solvent...

  16. Magnetic Properties and Phase Composition of Metamaterials Based on an Opal Matrix with 3 d-Transition Metal Particles

    Science.gov (United States)

    Rinkevich, A. B.; Korolev, A. V.; Samoilovich, M. I.; Perov, D. V.; Nemytova, O. V.

    2018-02-01

    The magnetic properties of metamaterials based on an opal matrix with transition-metal (iron, nickel, cobalt) particles have been studied. Magnetization curves and magnetic hysteresis loops have been measured and the dependences of real and imaginary parts of magnetization have been determined using the dynamic ac susceptibility measuring procedure. Structural studies of metamaterials have been performed. The saturation magnetization and coercive force of the studied metamaterials have been found to depend weakly on the temperature. The temperature dependence of magnetic susceptibility at a temperature above 30 K can be described adequately by Curie-Weiss law and, at lower temperature, deviates from the law.

  17. Synthesis and mechanical properties of conventionally cast icosahedral particle-reinforced Al-Mn(-Cu)-Be-Si alloys

    International Nuclear Information System (INIS)

    Fleury, E.; Chang, H.J.; Kim, D.H.; Kim, D.H.; Kim, W.T.

    2005-01-01

    The microstructure of the Al-Mn(-Cu)-Be-Si alloys analyzed by X-ray diffraction and TEM consisted of icosahedral (i) quasicrystal particles embedded in α Al matrix. The conjoint addition of Si and Be elements enabled the i-phase formation in diameter 10 mm specimens prepared by conventional casting technique. The size, volume fraction and stability of the i-phase were found to be dependent on the Mn content. The addition of 2 at.% Cu did not affect the formation and stability of the i-phase but contributed significantly to the enhancement of the mechanical properties. (orig.)

  18. Synthesis and electrochemical properties of different sizes of the CuO particles

    International Nuclear Information System (INIS)

    Zhang Xiaojun; Zhang Dongen; Ni Xiaomin; Song Jimei; Zheng Huagui

    2008-01-01

    Well-dispersed cupric oxide (CuO) nanoparticles with the size from 10 to 100 nm were successfully synthesized by thermal decomposition of CuC 2 O 4 precursor at 400 deg. C. The prepared CuO nanoparticles of different sizes used as anode materials for Li ion battery all exhibit high electrochemical capacity at the first discharge. However, with the particles size changing, an interesting phenomenon appears. That is, the larger size of the particles is, the discharge capacity of the first time smaller is, while that of the second time is larger. At the same time, the mechanism of the above phenomenon is discussed in this paper. Surprisingly, we have synthesized the copper nanoparticles with different sizes by the CuO of different sizes as the electrodes

  19. Synthesis and spectroscopic properties of silica-dye-semiconductor nanocrystal hybrid particles.

    Science.gov (United States)

    Ren, Ting; Erker, Wolfgang; Basché, Thomas; Schärtl, Wolfgang

    2010-12-07

    We prepared silica-dye-nanocrystal hybrid particles and studied the energy transfer from semiconductor nanocrystals (= donor) to organic dye molecules (= acceptor). Multishell CdSe/CdS/ZnS semiconductor nanocrystals were adsorbed onto monodisperse Stöber silica particles with an outer silica shell of thickness 2-23 nm containing organic dye molecules (Texas Red). The thickness of this dye layer has a strong effect on the energy transfer efficiency, which is explained by the increase in the number of dye molecules homogeneously distributed within the silica shell, in combination with an enhanced surface adsorption of nanocrystals with increasing dye amount. Our conclusions were underlined by comparison of the experimental results with numerically calculated FRET efficiencies and by control experiments confirming attractive interaction between the nanocrystals and Texas Red freely dissolved in solution.

  20. Heteronanostructure of Ag particle on titanate nanowire membrane with enhanced photocatalytic properties and bactericidal activities

    International Nuclear Information System (INIS)

    Shang Lu; Li Bingjie; Dong Wenjun; Chen Benyong; Li Chaorong; Tang Weihua; Wang Ge; Wu Jian; Ying Yibin

    2010-01-01

    A novel seed induced method has been developed for syntheses of Ag particles on titanate nanowires, and then the heteronanostructured Ag/titanate nanowires were assembled into porous, flexible membranes. These titanate nanowires were about several hundreds micrometers in length and about 80 nm in diameter. The size of the Ag particle can be tuned within 300-700 nm. The pore size and thickness of the heteronanostructured membrane were easily controlled. An Ag/titanate nanowire membrane reactor has been developed to study the photocatalytic degradation of methamidophos in aqueous solution, and 87.0% of the methamidophos can be degraded in a concurrent filtration and photocatalytic oxidation process. The antibacterial activity was also investigated on the heteronanostructured membrane with UVA light (365 nm) irradiation, and a 99.99% satisfactory antibacterial effect on Escherichia coli was achieved.

  1. The exchange interaction effects on magnetic properties of the nanostructured CoPt particles

    Science.gov (United States)

    Komogortsev, S. V.; Iskhakov, R. S.; Zimin, A. A.; Filatov, E. Yu.; Korenev, S. V.; Shubin, Yu. V.; Chizhik, N. A.; Yurkin, G. Yu.; Eremin, E. V.

    2016-03-01

    Various manifestations of the exchange interaction effects in magnetization curves of the CoPt nanostructured particles are demonstrated and discussed. The inter-grain exchange constant A in the sponge-like agglomerates of crystallites is estimated as A=(7±1) pJ/m from the approach magnetization to saturation curves that is in good agreement with A=(6.6±0.5) pJ/m obtained from Bloch T 3/2 law. The fractal dimensionality of the exchange coupled crystallite system in the porous media of the disordered CoPt alloy d=(2.60±0.18) was estimated from the approach magnetization to saturation curve. Coercive force decreases with temperature as Hc T 3/2 which is assumed to be a consequence of the magnetic anisotropy energy reduction due to the thermal spin wave excitations in the investigated CoPt particles.

  2. 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.

  3. Some properties of charmed particles produced in π--nucleus interactions

    International Nuclear Information System (INIS)

    Aoki, S.; Chiba, K.; Hoshino, K.; Kobayashi, M.; Kodama, K.; Miyanishi, M.; Nakamura, M.; Niu, K.; Niwa, K.; Ohashi, M.; Sasaki, H.; Tajima, H.; Tomita, Y.; Yamakawa, O.; Yanagisawa, Y.; Baroni, G.; Dell'Uomo, S.; De Vincenzi, M.; Diliberto, S.; Manfredini, A.; Martellotti, G.; Mazzoni, M.A.; Meddi, F.; Penso, G.; Petrera, S.; Pistilli, P.; Rosa, G.; Sgarbi, C.; Barth, M.; Bertrand-Coremans, G.; Roosen, R.; Bisi, V.; Gamba, D.; Giubellino, P.; Marzari-Chiesa, A.; Ramello, L.; Riccati, L.; Breslin, A.C.; Montwill, A.; Davis, D.H.; Esten, M.J.; Tovee, D.N.; Isokane, Y.; Tsuneoka, Y.; Kazuno, M.; Minakawa, F.; Shibuya, H.; Watanabe, S.; Sato, Y.; Shimizu, T.; Tezuka, I.

    1988-01-01

    The azimuthal correlation distribution of 102 charmed-particle pairs observed in the hybrid emulsion experiment WA75 is compared with theoretical predictions. The various pairs - (D - D 0 ), (D - D + ), (D 0 anti D 0 ) and (D + anti D 0 ) - all show, within statistical error, the same azimuthal correlation distribution, demonstrating its independence from the specific nature of the production channel. Among the decays of 150 charged charmed particles and 138 neutral ones seen, higher multiplicities are favoured for hadronic as opposed to semileptonic decays. The data are consistent with the muonic decays of charged D mesons proceeding through the channels (μ ± , ν, K 0 ) and [μ ± , ν, K *0 (892)], the fraction through K 0 being 0.76±0.06. (orig.)

  4. 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

  5. Internal structure, hydroscopic and reactive properties of mixed sodium methanesulfonate-sodium chloride particles

    Czech Academy of Sciences Publication Activity Database

    Liu, Y.; Minofar, Babak; Desyaterik, Y.; Dames, E.; Zhu, Z.; Cain, J. P.; Hopkins, R. J.; Gilles, M. K.; Wang, H.; Jungwirth, Pavel; Laskin, A.

    2011-01-01

    Roč. 13, č. 25 (2011), s. 11846-11857 ISSN 1463-9076 R&D Projects: GA MŠk LC512; GA MŠk(CZ) LC06010 Grant - others:GA MŠk(CZ) ME09062 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z60870520 Keywords : sodium methanesulfonate particles * air/water interface * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.573, year: 2011

  6. Thermoplastic starch composites with TiO2 particles: preparation, morphology, rheology and mechanical properties

    Czech Academy of Sciences Publication Activity Database

    Ostafinska, Aleksandra; Mikešová, Jana; Krejčíková, Sabina; Nevoralová, Martina; Šturcová, Adriana; Zhigunov, Alexander; Michálková, Danuše; Šlouf, Miroslav

    2017-01-01

    Roč. 101, August (2017), s. 273-282 ISSN 0141-8130 R&D Projects: GA ČR(CZ) GA14-17921S Institutional support: RVO:61389013 Keywords : thermoplastic starch * titanium dioxide particles * morphology Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 3.671, year: 2016

  7. Physical and mechanical properties of bio-composites from wood particles and liquefied wood resin

    Science.gov (United States)

    Hui Pan; Todd F. Shupe; Chung-Yun Hse

    2009-01-01

    Compression molded composites were made from wood particles and a liquefied wood/phenol/formaldehyde co-condensed resin. Based on our previous research, a phenol to wood (P/W) ratio of 2/1 was chosen for this study. The two experimental variables selected were: 1) liquefaction temperature (150o and 180oC) and 2) cooking method (atmospheric and sealed). Panels were...

  8. Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

    International Nuclear Information System (INIS)

    Escobar-Cerezo, J.; Palmer, C.; Muñoz, O.; Moreno, F.; Penttilä, A.; Muinonen, K.

    2017-01-01

    The effect of internal inhomogeneities and surface roughness on the scattering behavior of large cosmic dust particles is studied by comparing model simulations with laboratory measurements. The present work shows the results of an attempt to model a dust sample measured in the laboratory with simulations performed by a ray-optics model code. We consider this dust sample as a good analogue for interplanetary and interstellar dust as it shares its refractive index with known materials in these media. Several sensitivity tests have been performed for both structural cases (internal inclusions and surface roughness). Three different samples have been selected to mimic inclusion/coating inhomogeneities: two measured scattering matrices of hematite and white clay, and a simulated matrix for water ice. These three matrices are selected to cover a wide range of imaginary refractive indices. The selection of these materials also seeks to study astrophysical environments of interest such as Mars, where hematite and clays have been detected, and comets. Based on the results of the sensitivity tests shown in this work, we perform calculations for a size distribution of a silicate-type host particle model with inclusions and surface roughness to reproduce the experimental measurements of a dust sample. The model fits the measurements quite well, proving that surface roughness and internal structure play a role in the scattering pattern of irregular cosmic dust particles.

  9. Electronic Properties of DNA-Based Schottky Barrier Diodes in Response to Alpha Particles.

    Science.gov (United States)

    Al-Ta'ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2015-05-21

    Detection of nuclear radiation such as alpha particles has become an important field of research in recent history due to nuclear threats and accidents. In this context; deoxyribonucleic acid (DNA) acting as an organic semiconducting material could be utilized in a metal/semiconductor Schottky junction for detecting alpha particles. In this work we demonstrate for the first time the effect of alpha irradiation on an Al/DNA/p-Si/Al Schottky diode by investigating its current-voltage characteristics. The diodes were exposed for different periods (0-20 min) of irradiation. Various diode parameters such as ideality factor, barrier height, series resistance, Richardson constant and saturation current were then determined using conventional, Cheung and Cheung's and Norde methods. Generally, ideality factor or n values were observed to be greater than unity, which indicates the influence of some other current transport mechanism besides thermionic processes. Results indicated ideality factor variation between 9.97 and 9.57 for irradiation times between the ranges 0 to 20 min. Increase in the series resistance with increase in irradiation time was also observed when calculated using conventional and Cheung and Cheung's methods. These responses demonstrate that changes in the electrical characteristics of the metal-semiconductor-metal diode could be further utilized as sensing elements to detect alpha particles.

  10. Electronic Properties of DNA-Based Schottky Barrier Diodes in Response to Alpha Particles

    Directory of Open Access Journals (Sweden)

    Hassan Maktuff Jaber Al-Ta'ii

    2015-05-01

    Full Text Available Detection of nuclear radiation such as alpha particles has become an important field of research in recent history due to nuclear threats and accidents. In this context; deoxyribonucleic acid (DNA acting as an organic semiconducting material could be utilized in a metal/semiconductor Schottky junction for detecting alpha particles. In this work we demonstrate for the first time the effect of alpha irradiation on an Al/DNA/p-Si/Al Schottky diode by investigating its current-voltage characteristics. The diodes were exposed for different periods (0–20 min of irradiation. Various diode parameters such as ideality factor, barrier height, series resistance, Richardson constant and saturation current were then determined using conventional, Cheung and Cheung’s and Norde methods. Generally, ideality factor or n values were observed to be greater than unity, which indicates the influence of some other current transport mechanism besides thermionic processes. Results indicated ideality factor variation between 9.97 and 9.57 for irradiation times between the ranges 0 to 20 min. Increase in the series resistance with increase in irradiation time was also observed when calculated using conventional and Cheung and Cheung’s methods. These responses demonstrate that changes in the electrical characteristics of the metal-semiconductor-metal diode could be further utilized as sensing elements to detect alpha particles.

  11. Structural, optical, XPS and magnetic properties of Zn particles capped by ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Iu.G., E-mail: yugmor@hotmail.com [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Academician Osipyan Street 8, Chernogolovka, Moscow Region 142432 (Russian Federation); Belousova, O.V. [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Academician Osipyan Street 8, Chernogolovka, Moscow Region 142432 (Russian Federation); Ortega, D., E-mail: daniel.ortega@imdea.org [Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco 28049, Madrid (Spain); Mafina, M.-K., E-mail: m.k.mafina@qmul.ac.uk [School of Engineering and Materials Science, Queen Mary University of London, Mile End, Eng, 231, London E1 4NS (United Kingdom); Kuznetcov, M.V., E-mail: maxim1968@mail.ru [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2015-06-05

    Highlights: • Levitation-jet aerosol synthesis of Zn particles capped by ZnO nanoparticles (NPs). • TEM, XRD, UV–vis, FT-IR, Raman, XPS and magnetic characterization of the NPs. • Correlation between unit-cell volume of crystal lattice and maximum magnetization. - Abstract: Spherical zinc particles ranging from 42 to 760 nm in average size and capped with plate-like zinc oxide particles of 10–30 nm in sizes have been prepared by levitation-jet aerosol synthesis through condensation of zinc vapor in an inert/oxidizer gas flow. The nanoparticles have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), BET measurements, ultra violet visible (UV–vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray electron spectroscopy (XPS), superconducting quantum interference device (SQUID), and vibrating-sample magnetometer (VSM). Magnetic and XRD data indicate that the observed ferromagnetic ordering related to the changes in unit-cell volume of Zn in the Zn/ZnO interface of the nanoparticles. These results are in good correlation with the optical measurements data.

  12. Electromagnetic properties for arbitrary spin particles: Natural electromagnetic moments from light-cone arguments

    International Nuclear Information System (INIS)

    Lorce, Cedric

    2009-01-01

    We revisit the old-standing problem of the electromagnetic interaction for particles of arbitrary spin. Based on the assumption that light-cone helicity at tree level and Q 2 =0 should be conserved nontrivially by the electromagnetic interaction, we are able to derive all the natural electromagnetic moments for a pointlike particle of any spin. We provide here a transparent decomposition of the electromagnetic current in terms of covariant vertex functions. We also define in a general way the electromagnetic multipole form factors, and show their relation with the electromagnetic moments and covariant vertex functions. The light-cone helicity conservation argument determines uniquely the values of all electromagnetic moments, which we refer to as the 'natural' ones. These specific values are in accordance with the standard model, and the prediction of universal g=2 gyromagnetic factor is naturally recovered. We provide a very simple and compact formula for these natural moments. As an application of our results, we generalize the discussion of quark transverse charge densities to particles with arbitrary spin, giving more physical support to the light-cone helicity conservation argument.

  13. The exchange interaction effects on magnetic properties of the nanostructured CoPt particles

    Energy Technology Data Exchange (ETDEWEB)

    Komogortsev, S.V., E-mail: komogor@iph.krasn.ru [Kirensky Institute of Physics, SB RAS, 660036 Krasnoyarsk (Russian Federation); Iskhakov, R.S. [Kirensky Institute of Physics, SB RAS, 660036 Krasnoyarsk (Russian Federation); Zimin, A.A. [Siberian Federal University, 660041 Krasnoyarsk (Russian Federation); Filatov, E.Yu.; Korenev, S.V.; Shubin, Yu.V. [Nikolaev Institute of Inorganic Chemistry, SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Chizhik, N.A. [Siberian Federal University, 660041 Krasnoyarsk (Russian Federation); Yurkin, G.Yu.; Eremin, E.V. [Kirensky Institute of Physics, SB RAS, 660036 Krasnoyarsk (Russian Federation)

    2016-03-01

    Various manifestations of the exchange interaction effects in magnetization curves of the CoPt nanostructured particles are demonstrated and discussed. The inter-grain exchange constant A in the sponge-like agglomerates of crystallites is estimated as A=(7±1) pJ/m from the approach magnetization to saturation curves that is in good agreement with A=(6.6±0.5) pJ/m obtained from Bloch T {sup 3/2} law. The fractal dimensionality of the exchange coupled crystallite system in the porous media of the disordered CoPt alloy d=(2.60±0.18) was estimated from the approach magnetization to saturation curve. Coercive force decreases with temperature as H{sub c}~T {sup 3/2} which is assumed to be a consequence of the magnetic anisotropy energy reduction due to the thermal spin wave excitations in the investigated CoPt particles. - Highlights: • Nanostructured CoPt particles were synthesized and then annealed in He atmosphere. • The structure of the material and magnetization curves were studied. • The maximum on reduced coercivity vs grain size dependence was observed. • The dimensionality d of exchange coupled crystallite system was estimated. • Exchange stiffness constant A was estimated.

  14. Mechanical properties of concrete containing a high volume of tire-rubber particles.

    Science.gov (United States)

    Khaloo, Ali R; Dehestani, M; Rahmatabadi, P

    2008-12-01

    Due to the increasingly serious environmental problems presented by waste tires, the feasibility of using elastic and flexible tire-rubber particles as aggregate in concrete is investigated in this study. Tire-rubber particles composed of tire chips, crumb rubber, and a combination of tire chips and crumb rubber, were used to replace mineral aggregates in concrete. These particles were used to replace 12.5%, 25%, 37.5%, and 50% of the total mineral aggregate's volume in concrete. Cylindrical shape concrete specimens 15 cm in diameter and 30 cm in height were fabricated and cured. The fresh rubberized concrete exhibited lower unit weight and acceptable workability compared to plain concrete. The results of a uniaxial compressive strain control test conducted on hardened concrete specimens indicate large reductions in the strength and tangential modulus of elasticity. A significant decrease in the brittle behavior of concrete with increasing rubber content is also demonstrated using nonlinearity indices. The maximum toughness index, indicating the post failure strength of concrete, occurs in concretes with 25% rubber content. Unlike plain concrete, the failure state in rubberized concrete occurs gently and uniformly, and does not cause any separation in the specimen. Crack width and its propagation velocity in rubberized concrete are lower than those of plain concrete. Ultrasonic analysis reveals large reductions in the ultrasonic modulus and high sound absorption for tire-rubber concrete.

  15. Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Escobar-Cerezo, J.; Palmer, C.; Muñoz, O.; Moreno, F. [Instituto de Astrofìsica de Andalucìa, CSIC, Glorieta de la Astronomìa s/n, E-18008 Granada (Spain); Penttilä, A.; Muinonen, K. [Department of Physics, P.O. Box 64, FI-00014 University of Helsinki (Finland)

    2017-03-20

    The effect of internal inhomogeneities and surface roughness on the scattering behavior of large cosmic dust particles is studied by comparing model simulations with laboratory measurements. The present work shows the results of an attempt to model a dust sample measured in the laboratory with simulations performed by a ray-optics model code. We consider this dust sample as a good analogue for interplanetary and interstellar dust as it shares its refractive index with known materials in these media. Several sensitivity tests have been performed for both structural cases (internal inclusions and surface roughness). Three different samples have been selected to mimic inclusion/coating inhomogeneities: two measured scattering matrices of hematite and white clay, and a simulated matrix for water ice. These three matrices are selected to cover a wide range of imaginary refractive indices. The selection of these materials also seeks to study astrophysical environments of interest such as Mars, where hematite and clays have been detected, and comets. Based on the results of the sensitivity tests shown in this work, we perform calculations for a size distribution of a silicate-type host particle model with inclusions and surface roughness to reproduce the experimental measurements of a dust sample. The model fits the measurements quite well, proving that surface roughness and internal structure play a role in the scattering pattern of irregular cosmic dust particles.

  16. Effects of nano-particles strengthening activating flux on the microstructures and mechanical properties of TIG welded AZ31 magnesium alloy joints

    International Nuclear Information System (INIS)

    Xie, Xiong; Shen, Jun; Cheng, Liang; Li, Yang; Pu, Yayun

    2015-01-01

    Highlights: • Increased nano-particles strengthening activating flux degraded TIGed seams. • The reaction between SiC particles and Mg alloy produced Al 4 C 3 and Mg 2 Si phases. • Al 4 C 3 and SiC particles promoted the nucleation and suppressed the growth of α-Mg. • Refined α-Mg grains, precipitated phase and SiC particles enhanced TIGed joints. - Abstract: In this paper, AZ31 magnesium alloy joints were processed by nano-particles strengthening activating flux tungsten inert gas (NSA-TIG) welding, which was achieved by the mixed TiO 2 and nano-SiC particles coated on the samples before welding tests. The macro/micro structural observation and mechanical properties evaluation of the welding joints were conducted by using optical microscope, scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction and tension and microhardness tests. The results showed that nano-particles strengthening activating flux effective improved the microstructure, microhardness in fusion zone, ultimate tensile strength of the TIG welding joints. In addition, the chemical reaction between part of SiC particles and AZ31 magnesium alloy produced Al 4 C 3 and Mg 2 Si in the joints. The Al 4 C 3 performed as nucleating agents for α-Mg and the dispersed Mg 2 Si and SiC particles enhanced the mechanical properties of the NSA-TIG welding joints. However, large heat input induced by the increase of the surface coating density of the nano-particles strengthening activating flux, increased the α-Mg grain sizes and weakened the mechanical properties of the welded joints. Therefore, the grain size of α-Mg, distribution of β-Mg 17 Al 12 , Mg 2 Si and SiC particles together influenced the evolution of the mechanical properties of the NSA-TIG welded AZ31 magnesium alloy joints

  17. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Xu, J.L.; Huang, Z.X.; Luo, J.M.; Zhong, Z.C.

    2014-01-01

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H 2 SO 4 solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H 2 SO 4 solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates

  18. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.L., E-mail: jlxu@nchu.edu.cn; Huang, Z.X.; Luo, J.M.; Zhong, Z.C., E-mail: zzhong.2006@yahoo.com.cn

    2014-04-15

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H{sub 2}SO{sub 4} solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H{sub 2}SO{sub 4} solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates.

  19. Predictive Models of Nanotoxicity: Relationship of Physicochemical Properties to Particle Movement Through Biological Barriers

    Science.gov (United States)

    Understanding the linkage between the physicochemical (PC) properties of nanoparticles (NP) and their activation of biological systems is poorly understood, yet fundamental to predicting nanotoxicity, idenitifying mode of actions and developing appropriate and effective regul...

  20. Effect of particle size of granules on some mechanical properties of ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... granules on some tablet mechanical properties of paracetamol tablets. Granules ... massing paracetamol powder (200 g) with 20% (w/w) of maize starch mucilage as binder. .... The resulting tablets were stored overnight in a.

  1. Micromechanical analysis of a hybrid composite—effect of boron carbide particles on the elastic properties of basalt fiber reinforced polymer composite

    Science.gov (United States)

    Krishna Golla, Sai; Prasanthi, P.

    2016-11-01

    A fiber reinforced polymer (FRP) composite is an important material for structural application. The diversified application of FRP composites has become the center of attention for interdisciplinary research. However, improvements in the mechanical properties of this class of materials are still under research for different applications. The reinforcement of inorganic particles in a composite improves its structural properties due to their high stiffness. The present research work is focused on the prediction of the mechanical properties of the hybrid composites where continuous fibers are reinforced in a micro boron carbide particle mixed polypropylene matrix. The effectiveness of the addition of 30 wt. % of boron carbide (B4C) particle contributions regarding the longitudinal and transverse properties of the basalt fiber reinforced polymer composite at various fiber volume fractions is examined by finite element analysis (FEA). The experimental approach is the best way to determine the properties of the composite but it is expensive and time-consuming. Therefore, the finite element method (FEM) and analytical methods are the viable methods for the determination of the composite properties. The FEM results were obtained by adopting a micromechanics approach with the support of FEM. Assuming a uniform distribution of reinforcement and considering one unit-cell of the whole array, the properties of the composite materials are determined. The predicted elastic properties from FEA are compared with the analytical results. The results suggest that B4C particles are a good reinforcement for the enhancement of the transverse properties of basalt fiber reinforced polypropylene.

  2. Investigation of the effects of particle size on the mechanical properties of porous and tin infiltrated niobium rods fabricated by a thermoplastic-powder metallurgy technique

    International Nuclear Information System (INIS)

    Noman, A.

    1978-12-01

    An investigation was made of the influence of particle size on the properties of both porous and tin infiltrated niobium rods fabricated by a thermoplastic-powder metallurgy technique. The residual porosity, extrusion pressure, tensile strength, and ductility were found to be dependent on the particle size distribution. All of these parameters were found to increase with increasing particle size. The influence of sintering time at a temperature of 2250 0 C was also studied. With increasing sintering time, the residual porosity and tensile strength decreased, whereas the ductility increased. The procedures for fabricating infiltrated niobium rods and the various tests employed to determine their properties are described

  3. Shielding properties of the ordinary concrete loaded with micro- and nano-particles against neutron and gamma radiations.

    Science.gov (United States)

    Mesbahi, Asghar; Ghiasi, Hosein

    2018-06-01

    The shielding properties of ordinary concrete doped with some micro and nano scaled materials were studied in the current study. Narrow beam geometry was simulated using MCNPX Monte Carlo code and the mass attenuation coefficient of ordinary concrete doped with PbO 2 , Fe 2 O 3 , WO 3 and H 4 B (Boronium) in both nano and micro scales was calculated for photon and neutron beams. Mono-energetic beams of neutrons (100-3000 keV) and photons (142-1250 keV) were used for calculations. The concrete doped with nano-sized particles showed higher neutron removal cross section (7%) and photon attenuation coefficient (8%) relative to micro-particles. Application of nano-sized material in the composition of new concretes for dual protection against neutrons and photons are recommended. For further studies, the calculation of attenuation coefficients of these nano-concretes against higher energies of neutrons and photons and different particles are suggested. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Structural and Morphological Properties of Nanostructured ZnO Particles Grown by Ultrasonic Spray Pyrolysis Method with Horizontal Furnace

    Directory of Open Access Journals (Sweden)

    G. Flores-Carrasco

    2014-01-01

    Full Text Available ZnO nanoparticles were synthesized in a horizontal furnace at 500°C using different zinc nitrate hexahydrate concentrations (0.01 and 0.1 M as reactive solution by ultrasonic spray pyrolysis method. The physical-chemical properties of synthesized ZnO nanoparticles have been characterized by thermogravimetric analysis (TGA, X-ray diffraction (XRD, scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS, and high resolution transmission electron microscopy (HRTEM. With the TGA is has optimized the temperature at which the initial reactive (Zn(NO32·6H2O, is decomposed completely to give way to its corresponding oxide, ZnO. SEM revealed secondary particles with a quasispherical shape that do not change significantly with the increasing of precursor solution concentration as well as some content of the broken spheres. Increasing the precursor solution concentration leads to the increase in the average size of ZnO secondary particles from 248±73 to 470±160 nm; XRD reveals the similar tendency for the crystallite size which changes from 23±4 to 45±4 nm. HRTEM implies that the secondary particles are with hierarchical structure composed of primary nanosized subunits. These results showed that the precursor concentration plays an important role in the evolution on the size, stoichiometry, and morphology of ZnO nanoparticles.

  5. Critical solvent properties affecting the particle formation process and characteristics of celecoxib-loaded plga microparticles via spray-drying.

    Science.gov (United States)

    Wan, Feng; Bohr, Adam; Maltesen, Morten Jonas; Bjerregaard, Simon; Foged, Camilla; Rantanen, Jukka; Yang, Mingshi

    2013-04-01

    It is imperative to understand the particle formation mechanisms when designing advanced nano/microparticulate drug delivery systems. We investigated how the solvent power and volatility influence the texture and surface chemistry of celecoxib-loaded poly (lactic-co-glycolic acid) (PLGA) microparticles prepared by spray-drying. Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties and drug release profile. The evaporation profiles of the feed solutions were investigated using thermogravimetric analysis (TGA). Spherical PLGA microparticles were obtained, irrespectively of the solvent composition. The particle size and surface chemistry were highly dependent on the solvent power of the feed solution. An obvious burst release was observed for the microparticles prepared by the feed solutions with the highest amount of poor solvent for PLGA. TGA analysis revealed distinct drying kinetics for the binary mixtures. The particle formation process is mainly governed by the PLGA precipitation rate, which is solvent-dependent, and the migration rate of celecoxib molecules during drying. The texture and surface chemistry of the spray-dried PLGA microparticles can therefore be tailored by adjusting the solvent composition.

  6. Dynamic and Thermal Properties of Aluminum Alloy A356/Silicon Carbide Hollow Particle Syntactic Foams

    Directory of Open Access Journals (Sweden)

    James Cox

    2014-12-01

    Full Text Available Aluminum alloy A356 matrix syntactic foams filled with SiC hollow particles (SiCHP are studied in the present work. Two compositions of syntactic foams are studied for quasi-static and high strain rate compression. In addition, dynamic mechanical analysis is conducted to study the temperature dependent energy dissipation and damping capabilities of these materials. The thermal characterization includes study of the coefficient of thermal expansion (CTE. A356/SiCHP syntactic foams are not strain rate sensitive as the compressive strength displayed little variation between the tested strain rates of 0.001–2100 s−1. Microscopic analysis of the high strain rate compression tested specimens showed that the fracture is initiated by the failure of hollow particles at the onset of the plastic deformation region. This is followed by plastic deformation of the matrix material and further crushing of particles. The syntactic foams showed decrease in storage modulus with increasing temperature and the trend was nearly linear up to 500 °C. The alloy shows a similar behavior at low temperature but the decrease in storage modulus increases sharply over 375 °C. The loss modulus is very small for the tested materials because of lack of viscoelasticity in metallic materials. The trend in the loss modulus is opposite, where the matrix alloy has lower loss modulus than syntactic foams at low temperature. However, over 250 °C the matrix loss modulus starts to increase rapidly and attains a peak around 460 °C. Syntactic foams have higher damping parameter at low temperatures than the matrix alloy. Incorporation of SiCHP helps in decreasing CTE. Compared to the CTE of the matrix alloy, 23.4 × 10−6 °C−1, syntactic foams showed CTE values as low as 11.67 × 10−6 °C−1.

  7. Impact of variety type and particle size distribution on starch enzymatic hydrolysis and functional properties of tef flours.

    Science.gov (United States)

    Abebe, Workineh; Collar, Concha; Ronda, Felicidad

    2015-01-22

    Tef grain is becoming very attractive in the Western countries since it is a gluten-free grain with appreciated nutritional advantages. However there is little information of its functional properties and starch digestibility and how they are affected by variety type and particle size distribution. This work evaluates the effect of the grain variety and the mill used on tef flour physico-chemical and functional properties, mainly derived from starch behavior. In vitro starch digestibility of the flours by Englyst method was assessed. Two types of mills were used to obtain whole flours of different granulation. Rice and wheat flours were analyzed as references. Protein molecular weight distribution and flour structure by SEM were also analyzed to justify some of the differences found among the cereals studied. Tef cultivar and mill type exhibited important effect on granulation, bulking density and starch damage, affecting the processing performance of the flours and determining the hydration and pasting properties. The color was darker although one of the white varieties had a lightness near the reference flours. Different granulation of tef flour induced different in vitro starch digestibility. The disc attrition mill led to higher starch digestibility rate index and rapidly available glucose, probably as consequence of a higher damaged starch content. The results confirm the adequacy of tef flour as ingredient in the formulation of new cereal based foods and the importance of the variety and the mill on its functional properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. A Study on the Plasmonic Properties of Silver Core Gold Shell Nanoparticles: Optical Assessment of the Particle Structure

    Science.gov (United States)

    Mott, Derrick; Lee, JaeDong; Thi Bich Thuy, Nguyen; Aoki, Yoshiya; Singh, Prerna; Maenosono, Shinya

    2011-06-01

    This paper reports a qualitative comparison between the optical properties of a set of silver core, gold shell nanoparticles with varying composition and structure to those calculated using the Mie solution. To achieve this, silver nanoparticles were synthesized in aqueous phase from a silver hydroxide precursor with sodium acrylate as dual reducing-capping agent. The particles were then coated with a layer of gold with controllable thickness through a reduction-deposition process. The resulting nanoparticles reveal well defined optical properties that make them suitable for comparison to ideal calculated results using the Mie solution. The discussion focuses on the correlation between the synthesized core shell nanoparticles with varying Au shell thickness and the Mie solution results in terms of the optical properties. The results give insight in how to design and synthesize silver core, gold shell nanoparticles with controllable optical properties (e.g., SPR band in terms of intensity and position), and has implications in creating nanoparticle materials to be used as biological probes and sensing elements.

  9. Effects of tree species and wood particle size on the properties of cement-bonded particleboard manufacturing from tree prunings.

    Science.gov (United States)

    Nasser, Ramadan A; Al-Mefarrej, H A; Abdel-Aal, M A; Alshahrani, T S

    2014-09-01

    This study investigated the possibility of using the prunings of six locally grown tree species in Saudi Arabia for cement-bonded particleboard (CBP) production. Panels were made using four different wood particle sizes and a constant wood/cement ratio (1/3 by weight) and target density (1200 kg/m3). The mechanical properties and dimensional stability of the produced panels were determined. The interfacial area and distribution of the wood particles in cement matrix were also investigated by scanning electron microscopy. The results revealed that the panels produced from these pruning materials at a target density of 1200 kg m(-3) meet the strength and dimensional stability requirements of the commercial CBP panels. The mean moduli of rupture and elasticity (MOR and MOE) ranged from 9.68 to 11.78 N mm2 and from 3952 to 5667 N mm2, respectively. The mean percent water absorption for twenty four hours (WA24) ranged from 12.93% to 23.39%. Thickness swelling values ranged from 0.62% to 1.53%. For CBP panels with high mechanical properties and good dimensional stability, mixed-size or coarse particles should be used. Using the tree prunings for CBPs production may help to solve the problem of getting rid of these residues by reducing their negative effects on environment, which are caused by poor disposal of such materials through direct combustion process and appearance of black cloud and then the impact on human health or the random accumulation and its indirect effects on the environment.

  10. Variations in Spectral Absorption Properties of Phytoplankton, Non-algal Particles and Chromophoric Dissolved Organic Matter in Lake Qiandaohu

    Directory of Open Access Journals (Sweden)

    Liangliang Shi

    2017-05-01

    Full Text Available Light absorption by phytoplankton, non-algal particles (NAP and chromophoric dissolved organic matter (CDOM was investigated at 90 sites of a clear, deep artificial lake (Lake Qiandaohu to study natural variability of absorption coefficients. Our study shows that CDOM absorption is a major contributor to the total absorption signal in Lake Qiandaohu during all seasons, except autumn when it has an equivalent contribution as total particle absorption. The exponential slope of CDOM absorption varies within a narrow range around a mean value of 0.0164 nm−1 ( s d = 0.00176 nm−1. Our study finds some evidence for thIS autochthonous production of CDOM in winter and spring. Absorption by phytoplankton, and therefore its contribution to total absorption, is generally greatest in spring, suggesting that phytoplankton growth in Lake Qiandaohu occurs predominantly in the spring. Phytoplankton absorption in freshwater lakes generally has a direct relationship with chlorophyll-a concentration, similar to the one established for open ocean waters. The NAP absorption, whose relative contribution to total absorption is highest in summer, has a spectral shape that can be well fitted by an exponential function with an average slope of 0.0065 nm−1 ( s d = 0.00076 nm−1. There is significant spatial variability present in the summer of Lake Qiandaohu, especially in the northwestern and southwestern extremes where the optical properties of the water column are strongly affected by the presence of allochthonous matter. Variations in the properties of the particle absorption spectra with depths provides evidence that the water column was vertically inhomogeneous and can be monitored with an optical measurement program. Moreover, the optical inhomogeneity in winter is less obvious. Our study will support the parameterization of the Bio-optical model for Lake Qiandaohu from in situ or remotely sensing aquatic color signals.

  11. Optical properties of individual nano-sized gold particle pairs. Mie-scattering, fluorescence, and Raman-scattering

    Energy Technology Data Exchange (ETDEWEB)

    Olk, Phillip

    2008-07-01

    This thesis examines and exploits the optical properties of pairs of MNPs. Pairs of MNPs offer two further parameters not existent at single MNPs, which both affect the local optical fields in their vicinity: the distance between them, and their relative orientation with respect to the polarisation of the excitation light. These properties are subject of three chapters: One section examines the distance-dependent and orientation-sensitive scattering cross section (SCS) of two equally sized MNPs. Both near- and far-field interactions affect the spectral position and spectral width of the SCS. Far-field coupling affects the SCS even in such a way that a two-particle system may show both a blue- and redshifted SCS, depending only on the distance between the two MNPs. The maximum distance for this effect is the coherence length of the illumination source - a fact of importance for SCS-based experiments using laser sources. Another part of this thesis examines the near-field between two MNPs and the dependence of the locally enhanced field on the relative particle orientation with respect to the polarisation of the excitation light. To attain a figure of merit, the intensity of fluorescence light from dye molecules in the surrounding medium was measured at various directions of polarisation. The field enhancement was turned into fluorescence enhancement, even providing a means for sensing the presence of very small MNPs of 12 nm in diameter. In order to quantify the near-field experimentally, a different technique is devised in a third section of this thesis - scanning particle-enhanced Raman microscopy (SPRM). This device comprises a scanning probe carrying an MNP which in turn is coated with a molecule of known Raman signature. By manoeuvring this outfit MNP into the vicinity of an illuminated second MNP and by measuring the Raman signal intensity, a spatial mapping of the field enhancement was possible. (orig.)

  12. Experimental data on the properties of natural fiber particle reinforced polymer composite material

    Directory of Open Access Journals (Sweden)

    D. Chandramohan

    2017-08-01

    Full Text Available This paper presents an experimental study on the development of polymer bio-composites. The powdered coconut shell, walnut shells and Rice husk are used as reinforcements with bio epoxy resin to form hybrid composite specimens. The fiber compositions in each specimen are 1:1 while the resin and hardener composition 10:1 respectively. The fabricated composites were tested as per ASTM standards to evaluate mechanical properties such as tensile strength, flexural strength, shear strength and impact strength are evaluated in both with moisture and without moisture. The result of test shows that hybrid composite has far better properties than single fibre glass reinforced composite under mechanical loads. However it is found that the incorporation of walnut shell and coconut shell fibre can improve the properties.

  13. Experimental data on the properties of natural fiber particle reinforced polymer composite material.

    Science.gov (United States)

    Chandramohan, D; Presin Kumar, A John

    2017-08-01

    This paper presents an experimental study on the development of polymer bio-composites. The powdered coconut shell, walnut shells and Rice husk are used as reinforcements with bio epoxy resin to form hybrid composite specimens. The fiber compositions in each specimen are 1:1 while the resin and hardener composition 10:1 respectively. The fabricated composites were tested as per ASTM standards to evaluate mechanical properties such as tensile strength, flexural strength, shear strength and impact strength are evaluated in both with moisture and without moisture. The result of test shows that hybrid composite has far better properties than single fibre glass reinforced composite under mechanical loads. However it is found that the incorporation of walnut shell and coconut shell fibre can improve the properties.

  14. Size-dependent effective properties of anisotropic piezoelectric composites with piezoelectric nano-particles

    International Nuclear Information System (INIS)

    Huang, Ming-Juan; Fang, Xue-Qian; Liu, Jin-Xi; Feng, Wen-Jie; Zhao, Yong-Mao

    2015-01-01

    Based on the electro-elastic surface/interface theory, the size-dependent effective piezoelectric and dielectric coefficients of anisotropic piezoelectric composites that consist of spherically piezoelectric inclusions under a uniform electric field are investigated, and the analytical solutions for the elastic displacement and electric potentials are derived. With consideration of the coupling effects of elasticity, permittivity and piezoelectricity, the effective field method is introduced to derive the effective dielectric and piezoelectric responses in the dilute limit. The numerical examples show that the effective dielectric constant exhibits a significant variation due to the surface/interface effect. The dielectric property of the surface/interface displays greater effect than the piezoelectric property, and the elastic property shows little effect. A comparison with the existing results validates the present approach. (paper)

  15. Ice nucleation properties of fine ash particles from the Eyjafjallajökull eruption in April 2010

    Directory of Open Access Journals (Sweden)

    I. Steinke

    2011-12-01

    Full Text Available During the eruption of the Eyjafjallajökull volcano in the south of Iceland in April/May 2010, about 40 Tg of ash mass were emitted into the atmosphere. It was unclear whether volcanic ash particles with d < 10 μm facilitate the glaciation of clouds. Thus, ice nucleation properties of volcanic ash particles were investigated in AIDA (Aerosol Interaction and Dynamics in the Atmosphere cloud chamber experiments simulating atmospherically relevant conditions. The ash sample that was used for our experiments had been collected at a distance of 58 km from the Eyjafjallajökull during the eruption period in April 2010. The temperature range covered by our ice nucleation experiments extended from 219 to 264 K, and both ice nucleation via immersion freezing and deposition nucleation could be observed. Immersion freezing was first observed at 252 K, whereas the deposition nucleation onset lay at 242 K and RHice =126%. About 0.1% of the volcanic ash particles were active as immersion freezing nuclei at a temperature of 249 K. For deposition nucleation, an ice fraction of 0.1% was observed at around 233 K and RHice =116%. Taking ice-active surface site densities as a measure for the ice nucleation efficiency, volcanic ash particles are similarly efficient ice nuclei in immersion freezing mode (ns,imm ~ 109 m−2 at 247 K compared to certain mineral dusts. For deposition nucleation, the observed ice-active surface site densities ns,dep were found to be 1011 m−2 at 224 K and RHice =116%. Thus, volcanic ash particles initiate deposition nucleation more efficiently than Asian and Saharan dust but appear to be poorer ice nuclei than ATD particles. Based on the experimental data, we have derived ice-active surface site densities as a function of temperature for immersion freezing and of relative humidity over ice and temperature for

  16. Microstructures and properties of ceramic particle-reinforced metal matrix composite layers produced by laser cladding

    Science.gov (United States)

    Zhang, Qingmao; He, Jingjiang; Liu, Wenjin; Zhong, Minlin

    2005-01-01

    Different weight ratio of titanium, zirconium, WC and Fe-based alloy powders were mixed, and cladded onto a medium carbon steel substrate using a 3kW continuous wave CO2 laser, aiming at producing Ceramic particles- reinforced metal matrix composites (MMCs) layers. The microstructures of the layers are typical hypoeutectic, and the major phases are Ni3Si2, TiSi2, Fe3C, FeNi, MC, Fe7Mo3, Fe3B, γ(residual austenite) and M(martensite). The microstructure morphologies of MMCs layers are dendrites/cells. The MC-type reinforcements are in situ synthesis Carbides which main compositions consist of transition elements Zr, Ti, W. The MC-type particles distributed within dendrite and interdendritic regions with different volume fractions for single and overlapping clad layers. The MMCs layers are dense and free of cracks with a good metallurgical bonding between the layer and substrate. The addition ratio of WC in the mixtures has the remarkable effect on the microhardness of clad layers.

  17. Building a picture of students' conceptions of wave- and particle-like properties of quantum entities

    International Nuclear Information System (INIS)

    Mannila, Katja; Koponen, Ismo T.; Niskanen, Jouni A.

    2002-01-01

    Quantum mechanics is considered conceptually to be a demanding topic due to the classically counterintuitive nature of its basic concepts and entities. A study is carried out where a picture of students' conceptual understanding of quantum entities (quantum 'particles') is constructed. This is done by analysing students' qualitative problem solving. The problem used as a research tool in this study is based on an example of the gradual formation of interference pattern for either low intensity light or electron beam passing through a two-slit system. It is suggested that students' conceptions can be described with four distinct models of 'description categories', which are (a) quasi-classical (particle ontology based), (b) trajectory based, (c) statistical (probabilistic) and (d) quasi-quantum models. In most cases the responses are dominated by classical pictures and trajectory based reasoning, described by categories (a) and (b). In just a few cases, the responses give evidence of the formation of new quantum ontology. In these cases, the students' responses can be described adequately by a combination of categories (c) and (d). (author)

  18. New Setup of the UAS ALADINA for Measuring Boundary Layer Properties, Atmospheric Particles and Solar Radiation

    Directory of Open Access Journals (Sweden)

    Konrad Bärfuss

    2018-01-01

    Full Text Available The unmanned research aircraft ALADINA (Application of Light-weight Aircraft for Detecting in situ Aerosols has been established as an important tool for boundary layer research. For simplified integration of additional sensor payload, a flexible and reliable data acquisition system was developed at the Institute of Flight Guidance, Technische Universität (TU Braunschweig. The instrumentation consists of sensors for temperature, humidity, three-dimensional wind vector, position, black carbon, irradiance and atmospheric particles in the diameter range of ultra-fine particles up to the accumulation mode. The modular concept allows for straightforward integration and exchange of sensors. So far, more than 200 measurement flights have been performed with the robustly-engineered system ALADINA at different locations. The obtained datasets are unique in the field of atmospheric boundary layer research. In this study, a new data processing method for deriving parameters with fast resolution and to provide reliable accuracies is presented. Based on tests in the field and in the laboratory, the limitations and verifiability of integrated sensors are discussed.

  19. Properties of plutonium-contaminated particles resulting from British Vixen B trials at Maralinga

    International Nuclear Information System (INIS)

    Burns, P.A.; Cooper, M.B.; Williams, G.A.; Johnston, P.N.

    1990-12-01

    Since 1984 a number of studies have been performed to investigate residual contamination at the former atomic weapons test site at Maralinga in South Australia, and to aid in the rehabilitation of the area. The largest site of plutonium contamination at Maralinga results from twelve Vixen B trials conduced at Taranaki in 1960, 1961 and 1963. Plutonium was dispersed along four major plumes from these trials. Measurements of the ratios of activities of 239 Pu and 240 Pu to 241 Am are presented for the plumes. These are identified with individual trials where possible. Some measurements have also been made of 235 U activities. An examination of meteorological and health physics survey data suggests that the most extensive part of the north-west plume results from a single trial, viz. Vixen B2 round 5 of 1961. It appears that the level of contamination in this plume was augmented by rainout of material, and the extent of the plume was enhanced by the considerable wind speed at the time. Results of proton-induced X-ray emission spectroscopy (PIXE), which provides elemental content and maps of the distribution of elements on the surface of some of the active particles, are presented, together with some other physical characteristics of the particles, in the expectation that these will aid in hazard assessment and with the development of techniques to rehabilitate the Taranaki site at Maralinga. 17 refs., 4 tabs., 1 fig

  20. Synthesis Structural and Optical Properties Of (Co, Al) co-doped ZnO Nano Particles

    Science.gov (United States)

    Swapna, P.; Venkatramana Reddy, S.

    2018-02-01

    We prepared (Co, Al) co-doped ZnO nanostructures using the method chemical co-precipitation successfully, at room temperature using PEG (Poly ethylene glycol) as stabilizing agent. Samples are prepared with different concentrations by keeping aluminium at 5 mol percent constant and varying the concentration of cobalt from 1 to 5 mol percent. After the preparation all the samples are carefully subjected to characterizations such as XRD, SEM with EDS, TEM, PL and UV-VIS-NIR. XRD pattern shows that all the samples possess hexagonal wurtzite crystal structure having no secondary phases pertaining to Al or cobalt, which shows successful dissolution of the dopents. TEM results shows the accurate size of particles and is confirmed the XRD data. SEM images of all the samples shows that particles are in nearly spherical shape, EDS spectrum reveals that incorporation of cobalt and aluminum in host lattice. PL spectrum shows that all the samples containing two prominent peaks centered at 420 nm and 446 nm. UV-VIS-NIR spectra has shown three absorptions peaks in the range of wavelength 550 nm to 700 nm, which are ascribed as typical d-d transitions of cobalt ions.

  1. Influence of physicochemical properties of beryllium particles on cultured cell toxicity

    International Nuclear Information System (INIS)

    Finch, G.L.; Brooks, A.L.; Hoover, M.D.; Cuddihy, R.G.

    1988-01-01

    The toxicity of beryllium oxide (BeO)), beryllium metal, and beryllium sulfate (BeSO 4 ) was studied in two cell lines, Chinese hamster ovary cells (CHO) and lung epithelial cells (LEC). Beryllium oxide particles were prepared at either 500 or 1000 deg. C, and two different particle sizes of beryllium metal were used. Following a 20-h exposure to beryllium compounds, cells were grown in culture to quantitate cloning ability relative to controls as a measure of cell killing, The LEC cultures were more sensitive to beryllium cytotoxicity than the CHO cells. When expressed on the basis of the mass of material added to the cultures, the order of toxicity was BeSO 4 ≥ 500 deg. C -BeO > 1000 deg. C -BeO > Be metal (small) Be metal (large). When cytotoxic effects were expressed on the basis of particulate surface rather than mass, the relative differences in toxicity between compounds was decreased. The order of toxicity was Be metal (small) ∼ Be metal (large) ∼ 500 deg. C-BeO ∼ 1000 deg. C-BeO. These data indicate that solubility influences beryllium toxicity to short-term cell cultures. (author)

  2. Effect of particle size and morphology on the properties of luminescence in ZnWO4

    International Nuclear Information System (INIS)

    Lisitsyn, V.M.; Valiev, D.T.; Tupitsyna, I.A.; Polisadova, E.F.; Oleshko, V.I.; Lisitsyna, L.A.; Andryuschenko, L.A.; Yakubovskaya, A.G.; Vovk, O.M.

    2014-01-01

    We investigated pulsed photoluminescence and pulsed cathodoluminescence in ZnWO 4 crystals and composite materials based on dispersed powders of zinc tungstate in the polymer matrix. It is shown that the size of crystal particles affects the luminescence decay time in excitation by electron and laser radiation. The decay time obtained for the composite material with nanoparticles 25 nm and 100 nm in size is equal to 5 µs and 7 µs, respectively. Relative values of the light yield of composite containing zinc tungstate crystals in the form of rods are found to be larger in comparison with crystallites in the form of grains. The mechanisms of luminescence recombination in laser and electron excitation are discussed. - Highlights: • Pulsed photoluminescence and pulsed cathodoluminescence spectra and decay kinetics of nano- and microcrystals of zinc tungstate in the organosilicic matrix compared to a single crystal were studied. • The luminescence decay kinetics and life-time of the excited state depend on the size of particles in the composite materials and on the type of excitation. • The probability of excitation of luminescence centers responsible for the band at 490 nm is higher which is apparently due to the larger capture cross-section and quantum yield

  3. Effect of particles size on mechanical properties of polypropylene particulate composites

    Czech Academy of Sciences Publication Activity Database

    Nezbedová, E.; Krčma, F.; Majer, Z.; Hutař, Pavel

    2016-01-01

    Roč. 7, č. 5 (2016), s. 690-699 ISSN 1757-9864 Institutional support: RVO:68081723 Keywords : Morphology * Mechanical properties * Numerical simulation * Polypropylene particulate composite s * Plasma surface treatment Subject RIV: JI - Composite Material s www.emeraldinsight.com/1757-9864.htm

  4. Methods for assessing basic particle properties and cytotoxicity of engineered nanoparticles

    NARCIS (Netherlands)

    Kalantzi, O.I.; Biskos, G.

    2014-01-01

    The increasing penetration of materials and products containing engineered nanoparticles (ENPs) to the market is posing many concerns regarding their environmental impacts. To assess these impacts, there is an urgent need of techniques for determining the health-related properties of ENPs and

  5. Physical properties and concentration of aerosol particles over the Amazon tropical forest during background and biomass burning conditions

    Directory of Open Access Journals (Sweden)

    P. Guyon

    2003-01-01

    Full Text Available We investigated the size distribution, scattering and absorption properties of Amazonian aerosols and the optical thickness of the aerosol layer under the pristine background conditions typical of the wet season, as well as during the biomass-burning-influenced dry season. The measurements were made during two campaigns in 1999 as part of the European contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH. In moving from the wet to the dry season, median particle numbers were observed to increase from values comparable to those of the remote marine boundary layer (~400 cm-3 to values more commonly associated with urban smog (~4000 cm-3, due to a massive injection of submicron smoke particles. Aerosol optical depths at 500 nm increased from 0.05 to 0.8 on average, reaching a value of 2 during the dry season. Scattering and absorption coefficients, measured at 550 nm, showed a concomitant increase from average values of 6.8 and 0.4 Mm-1 to values of 91 and 10 Mm-1, respectively, corresponding to an estimated decrease in single-scattering albedo from ca. 0.97 to 0.91. The roughly tenfold increase in many of the measured parameters attests to the dramatic effect that extensive seasonal biomass burning (deforestation, pasture cleaning is having on the composition and properties of aerosols over Amazonia. The potential exists for these changes to impact on regional and global climate through changes to the extinction of solar radiation as well as the alteration of cloud properties.

  6. Mechanical properties and ion release from bioactive restorative composites containing glass fillers and calcium phosphate nano-structured particles.

    Science.gov (United States)

    Chiari, Marina D S; Rodrigues, Marcela C; Xavier, Tathy A; de Souza, Eugen M N; Arana-Chavez, Victor E; Braga, Roberto R

    2015-06-01

    To evaluate the effect of the replacement of barium glass by dicalcium phosphate dihydrate (DCPD) particles on the mechanical properties and degree of conversion (DC) of composites. Additionally, calcium and hydrogen phosphate (HPO4(2-)) release were followed for 28 days. Nine composites containing equal parts (in mols) of BisGMA and TEGDMA and 40, 50 or 60 vol% of total filler were manipulated. Filler phase was constituted by silanated barium glass and 0%, 10% or 20% of DCPD particles. DC was determined by near-FTIR. Biaxial flexural strength (BFS) and modulus (E) were tested using the "piston on three balls" method, while fracture toughness (KIc) used the "single edge notched beam" method. Specimens were tested after 24h and 28 days in water. Ion release was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey (DC and ion release) or Kruskal-Wallis/Mann-Whitney (mechanical properties; alpha: 5%). DC was not affected by DCPD. The presence of DCPD reduced BFS for both storage times, while differences in E became evident after 28 days. After 24h, KIc increased with the addition of DCPD; after 28 days, however, KIc decreased only for DCPD-containing composites. Calcium release was similar for both DCPD contents and remained fairly constant during the 28-day period. Overall, HPO4(2-) release was higher at 7 days and did not decrease after 14 days. The composite with the highest filler level and 10% DCPD represented the best compromise between mechanical properties after aging in water and ion release. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Vacuum Simulations in High Energy Accelerators and Distribution Properties of Continuous and Discrete Particle Motions

    CERN Document Server

    Aichinger, Ida; Kersevan, Roberto

    The underlying thesis on mathematical simulation methods in application and theory is structured into three parts. The first part sets up a mathematical model capable of predicting the performance and operation of an accelerator’s vacuum system based on analytical methods. A coupled species-balance equation system describes the distribution of the gas dynamics in an ultra-high vacuum system considering impacts of conductance limitations, beam induced effects (ion-, electron-, and photon-induced de- sorption), thermal outgassing and sticking probabilities of the chamber materials. A new solving algorithm based on sparse matrix representations, is introduced and presents a closed form solution of the equation system. The model is implemented in a Python environment, named PyVasco, and is supported by a graphical user interface to make it easy available for everyone. A sensitivity analysis, a cross-check with the Test-Particle Monte Carlo simulation program Molflow+ and a comparison of the simulation results t...

  8. High temperature tribological properties of plasma-sprayed metallic coatings containing ceramic particles

    International Nuclear Information System (INIS)

    Dallaire, S.; Legoux, J.G.

    1995-01-01

    For sealing a moving metal component with a dense silica-based ceramic pre-heated at 800 C, coatings with a low coefficient of friction and moderate wear loss are required. As reported previously, plasma-sprayed coatings containing solid lubricants could reduce sliding wear in high-temperature applications. Plasma-sprayed metal-based coatings containing ceramic particles have been considered for high temperature sealing. Selected metal powders (NiCoCrAlY, CuNi, CuNiIn,