Big Bang Day: 5 Particles - 3. The Anti-particle

CERN Multimedia

Franck Close

2008-01-01

Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 3. The Anti-particle. It appears to be the stuff of science fiction. Associated with every elementary particle is an antiparticle which has the same mass and opposite charge. Should the two meet and combine, the result is annihilation - and a flash of light. Thanks to mysterious processes that occurred after the Big Bang there are a vastly greater number of particles than anti-particles. So how could their elusive existence be proved? At CERN particle physicists are crashing together subatomic particles at incredibly high speeds to create antimatter, which they hope will finally reveal what happened at the precise moment of the Big Bang to create the repertoire of elementary particles and antiparticles in existence today.

Revealing virtual processes of a quantum Brownian particle in phase space

International Nuclear Information System (INIS)

Maniscalco, S

2005-01-01

The short-time dynamics of a quantum Brownian particle in a harmonic potential is studied in phase space. An exact non-Markovian analytic approach to calculate the time evolution of the Wigner function is presented. The dynamics of the Wigner function of an initially squeezed state is analysed. It is shown that virtual exchanges of energy between the particle and the reservoir, characterizing the non-Lindblad short-time dynamics where system-reservoir correlations are not negligible, show up in phase space

Studies of particle drying using non-invasive Raman spectrometry and particle size analysis.

Science.gov (United States)

Hamilton, Peter; Littlejohn, David; Nordon, Alison; Sefcik, Jan; Slavin, Paul; Dallin, Paul; Andrews, John

2011-05-21

The evaporation of methanol from needle-shaped particles of cellobiose octaacetate (COA) has been studied directly in a jacketed vacuum drier using in situ measurements by Raman spectrometry. A design of experiments (DoE) approach was used to investigate the effects of three parameters (method of agitation, % solvent loss on drying and jacket temperature), with the intention of minimising the drying time and extent of particle attrition. Drying curves based on Raman signals for methanol and COA in the spectra of the wet particles indicated the end of drying and revealed three stages in the drying process that could be used to monitor the progress of solvent removal in real time. Off-line particle size measurements based on laser diffraction were made to obtain information on the extent of attrition, to compare with the trends revealed by the Raman drying curves. The study demonstrated that non-invasive Raman spectrometry can be used to study the progress of drying during agitation of particles in a vacuum drier, allowing optimisation of operating conditions to minimise attrition and reduce drying times. Although a correlation between particle size and off-line Raman measurements of COA was demonstrated, it was not possible to derive equivalent information from the in situ Raman spectra owing to the greater effects of particle motion or bulk density variations of the particles in the drier.

Spinning self-dual particles

International Nuclear Information System (INIS)

Gamboa, J.; Rivelles, V.O.

1989-02-01

We study spinning self-dual particles in two dimensions. They are obtained from the chiral bosonic particle through the square root technique. We show that the resulting field theory can be either fermionic or bosonic and that the associated self-dual field reveals its Lorentz tensor structure which remains hidden in the usual formulations. We also calculate the spinning self-dual particle propagators using the BFV formalism. (author) [pt

Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

International Nuclear Information System (INIS)

Guo Zhanhu; Park, Sung; Wei Suying; Pereira, Tony; Moldovan, Monica; Karki, Amar B; Young, David P; Hahn, H Thomas

2007-01-01

Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer-particle interactions

SIMULATION OF TRANSLATIONAL - ROTATIONAL MOTION OF WOOD PARTICLES DURING THE PROCESS OF PARTICLE ORIENTATION

Directory of Open Access Journals (Sweden)

Sergey PLOTNIKOV

2014-09-01

Full Text Available The simulation from the motion of flat particle revealed that the fall depends on the height of the drop, the thickness and density of the particles and does not depend on its length and width. The drop in air is about 20% longer than in vacuum. During orientation from angular particles the velocity of rotating particles with a length of 150mm is reduced by 18%, for particles with a length of 75mm by 12%. This reduction increases linearly with decreasing density of particles. A velocity field acting on the particle in the fall and rotation was presented. The results of the study prove the possibility to reduce the scatter of the particles during the mat's formation, that in turns can increase the board’s bending strength.

Condensed elementary particle matter

International Nuclear Information System (INIS)

Kajantie, K.

1996-01-01

Quark matter is a special case of condensed elementary particle matter, matter governed by the laws of particle physics. The talk discusses how far one can get in the study of particle matter by reducing the problem to computations based on the action. As an example the computation of the phase diagram of electroweak matter is presented. It is quite possible that ultimately an antireductionist attitude will prevail: experiments will reveal unpredicted phenomena not obviously reducible to the study of the action. (orig.)

Experimental approach to Chernobyl hot particles

International Nuclear Information System (INIS)

Tcherkezian, V.; Shkinev, V.; Khitrov, L.; Kolesov, G.

1994-01-01

An experimental approach to the investigation of Chernobyl hot particles and some results are presented in this study. Hot particles (HP) were picked out from soil samples collected during the 1986-1990 radiogeochemical expeditions in the contaminated zone (within 30 km of the Nuclear Power Plant). A number of hot particles were studied to estimate their contribution to the total activity, investigate their surface morphology and determine the size distribution. Hot particles contribution to the total activity in the 30 km zone was found to be not less than 65%. Investigation of HP element composition (by neutron activation analysis and EPMA) and radionuclide composition (direct alpha- and gamma-spectrometry, including determination of Pu and Am in Hp) revealed certain peculiarities of HP, collected in the vicinity of the damaged Nuclear Power Plant. Some particles were shown to contain uranium and fission products in proportion to one another, correlating with those in the partially burnt fuel, which proves their 'fuel' origin. Another part of the HP samples has revealed element fractionation as well as the presence of some terrestrial components. (Author)

Particle Shape Anisotropy in Pickering Emulsions: Cubes and Peanuts

NARCIS (Netherlands)

de Folter, J.W.J.; Hutter, E.M.; Castillo, S.I.R.; Klop, K.E.; Philipse, A.P.; Kegel, W.K.

2014-01-01

We have investigated the effect of particle shape in Pickering emulsions by employing, for the first time, cubic and peanut-shaped particles. The interfacial packing and orientation of anisotropic microparticles are revealed at the single-particle level by direct microscopy observations. The uniform

Two-particle versus three-particle interactions in single ionization of helium by ion impact

International Nuclear Information System (INIS)

Schulz, M; Moshammer, R; Fischer, D; Ullrich, J

2004-01-01

We have performed kinematically complete experiments on single ionization of He by 100 MeV amu -1 C 6+ and 3.6 MeV amu -1 Au 24,53+ impact. By analysing doubly differential cross sections (DDCS) as a function of the momenta of all two-particle sub-systems we studied the importance of two-particle interactions. Furthermore, presenting the squared momenta of all three collision fragments simultaneously in a Dalitz plot, we evaluated the role of three-particle interactions. Finally, both for the DDCS and the Dalitz plots the corresponding correlation function was analysed. While the absolute cross sections confirm that ionization predominantly leads to a momentum exchange between the electron and the recoil-ion, the correlation function reveals strong correlations between the particles of any two-particle sub-system. Three-particle correlations, which are not accounted for by perturbative calculations, are quite significant as well, at least for certain kinematic conditions

Big Bang Day: 5 Particles - 2. The Quark

CERN Multimedia

Franck Close

2008-01-01

Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 2. The Quark "Three Quarks for Master Mark! Sure he hasn't got much of a bark." James Joyce's Finnegans Wake left its mark on modern physics when physicist Murray Gell Mann proposed this name for a group of hypothetical subatomic particles that were revealed in 1960 as the fundamental units of matter. Basic particles it seems are made up of even more basic units called quarks that make up 99.9% of visible material in the universe.. But why do we know so little about them? Quarks have never been seen as free particles but instead, inextricably bound together by the Strong Force that in turn holds the atomic nucleus together. This is the hardest of Nature's fundamental forces to crack, but recent theoretical advances, mean that the properties of the quark are at last being revealed.

Intercalation pathway in many-particle LiFePO4 electrode revealed by nanoscale state-of-charge mapping.

Science.gov (United States)

Chueh, William C; El Gabaly, Farid; Sugar, Joshua D; Bartelt, Norman C; McDaniel, Anthony H; Fenton, Kyle R; Zavadil, Kevin R; Tyliszczak, Tolek; Lai, Wei; McCarty, Kevin F

2013-03-13

The intercalation pathway of lithium iron phosphate (LFP) in the positive electrode of a lithium-ion battery was probed at the ∼40 nm length scale using oxidation-state-sensitive X-ray microscopy. Combined with morphological observations of the same exact locations using transmission electron microscopy, we quantified the local state-of-charge of approximately 450 individual LFP particles over nearly the entire thickness of the porous electrode. With the electrode charged to 50% state-of-charge in 0.5 h, we observed that the overwhelming majority of particles were either almost completely delithiated or lithiated. Specifically, only ∼2% of individual particles were at an intermediate state-of-charge. From this small fraction of particles that were actively undergoing delithiation, we conclude that the time needed to charge a particle is ∼1/50 the time needed to charge the entire particle ensemble. Surprisingly, we observed a very weak correlation between the sequence of delithiation and the particle size, contrary to the common expectation that smaller particles delithiate before larger ones. Our quantitative results unambiguously confirm the mosaic (particle-by-particle) pathway of intercalation and suggest that the rate-limiting process of charging is initiating the phase transformation by, for example, a nucleation-like event. Therefore, strategies for further enhancing the performance of LFP electrodes should not focus on increasing the phase-boundary velocity but on the rate of phase-transformation initiation.

Particles in flows

CERN Document Server

Galdi, Giovanni; Nečasová, Šárka

2017-01-01

This book aims to face particles in flows from many different, but essentially interconnected sides and points of view. Thus the selection of authors and topics represented in the chapters, ranges from deep mathematical analysis of the associated models, through the techniques of their numerical solution, towards real applications and physical implications. The scope and structure of the book as well as the selection of authors was motivated by the very successful summer course and workshop "Particles in Flows'' that was held in Prague in the August of 2014. This meeting revealed the need for a book dealing with this specific and challenging multidisciplinary subject, i.e. particles in industrial, environmental and biomedical flows and the combination of fluid mechanics, solid body mechanics with various aspects of specific applications.

Aging fingerprints in combustion particles

Science.gov (United States)

Zelenay, V.; Mooser, R.; Tritscher, T.; Křepelová, A.; Heringa, M. F.; Chirico, R.; Prévôt, A. S. H.; Weingartner, E.; Baltensperger, U.; Dommen, J.; Watts, B.; Raabe, J.; Huthwelker, T.; Ammann, M.

2011-05-01

Soot particles can significantly influence the Earth's climate by absorbing and scattering solar radiation as well as by acting as cloud condensation nuclei. However, despite their environmental (as well as economic and political) importance, the way these properties are affected by atmospheric processing is still a subject of discussion. In this work, soot particles emitted from two different cars, a EURO 2 transporter, a EURO 3 passenger vehicle, and a wood stove were investigated on a single-particle basis. The emitted exhaust, including the particulate and the gas phase, was processed in a smog chamber with artificial solar radiation. Single particle specimens of both unprocessed and aged soot were characterized using x-ray absorption spectroscopy and scanning electron microscopy. Comparison of the spectra from the unprocessed and aged soot particles revealed changes in the carbon functional group content, such as that of carboxylic carbon, which can be ascribed to both the condensation of secondary organic compounds on the soot particles and oxidation of primary soot particles upon photochemical aging. Changes in the morphology and size of the single soot particles were also observed upon aging. Furthermore, we show that the soot particles take up water in humid environments and that their water uptake capacity increases with photochemical aging.

Solar energetic particle anisotropies and insights into particle transport

Energy Technology Data Exchange (ETDEWEB)

Leske, R. A., E-mail: ral@srl.caltech.edu; Cummings, A. C.; Cohen, C. M. S.; Mewaldt, R. A.; Labrador, A. W.; Stone, E. C. [California Institute of Technology, Pasadena, CA 91125 (United States); Wiedenbeck, M. E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Christian, E. R.; Rosenvinge, T. T. von [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2016-03-25

As solar energetic particles (SEPs) travel through interplanetary space, their pitch-angle distributions are shaped by the competing effects of magnetic focusing and scattering. Measurements of SEP anisotropies can therefore reveal information about interplanetary conditions such as magnetic field strength, topology, and turbulence levels at remote locations from the observer. Onboard each of the two STEREO spacecraft, the Low Energy Telescope (LET) measures pitch-angle distributions for protons and heavier ions up to iron at energies of about 2-12 MeV/nucleon. Anisotropies observed using LET include bidirectional flows within interplanetary coronal mass ejections, sunward-flowing particles when STEREO was magnetically connected to the back side of a shock, and loss-cone distributions in which particles with large pitch angles underwent magnetic mirroring at an interplanetary field enhancement that was too weak to reflect particles with the smallest pitch angles. Unusual oscillations in the width of a beamed distribution at the onset of the 23 July 2012 SEP event were also observed and remain puzzling. We report LET anisotropy observations at both STEREO spacecraft and discuss their implications for SEP transport, focusing exclusively on the extreme event of 23 July 2012 in which a large variety of anisotropies were present at various times during the event.

Solar energetic particle anisotropies and insights into particle transport

Science.gov (United States)

Leske, R. A.; Cummings, A. C.; Cohen, C. M. S.; Mewaldt, R. A.; Labrador, A. W.; Stone, E. C.; Wiedenbeck, M. E.; Christian, E. R.; Rosenvinge, T. T. von

2016-03-01

As solar energetic particles (SEPs) travel through interplanetary space, their pitch-angle distributions are shaped by the competing effects of magnetic focusing and scattering. Measurements of SEP anisotropies can therefore reveal information about interplanetary conditions such as magnetic field strength, topology, and turbulence levels at remote locations from the observer. Onboard each of the two STEREO spacecraft, the Low Energy Telescope (LET) measures pitch-angle distributions for protons and heavier ions up to iron at energies of about 2-12 MeV/nucleon. Anisotropies observed using LET include bidirectional flows within interplanetary coronal mass ejections, sunward-flowing particles when STEREO was magnetically connected to the back side of a shock, and loss-cone distributions in which particles with large pitch angles underwent magnetic mirroring at an interplanetary field enhancement that was too weak to reflect particles with the smallest pitch angles. Unusual oscillations in the width of a beamed distribution at the onset of the 23 July 2012 SEP event were also observed and remain puzzling. We report LET anisotropy observations at both STEREO spacecraft and discuss their implications for SEP transport, focusing exclusively on the extreme event of 23 July 2012 in which a large variety of anisotropies were present at various times during the event.

Hydrodynamic Capture and Release of Passively Driven Particles by Active Particles Under Hele-Shaw Flows

Science.gov (United States)

Mishler, Grant; Tsang, Alan Cheng Hou; Pak, On Shun

2018-03-01

The transport of active and passive particles plays central roles in diverse biological phenomena and engineering applications. In this paper, we present a theoretical investigation of a system consisting of an active particle and a passive particle in a confined micro-fluidic flow. The introduction of an external flow is found to induce the capture of the passive particle by the active particle via long-range hydrodynamic interactions among the particles. This hydrodynamic capture mechanism relies on an attracting stable equilibrium configuration formed by the particles, which occurs when the external flow intensity exceeds a certain threshold. We evaluate this threshold by studying the stability of the equilibrium configurations analytically and numerically. Furthermore, we study the dynamics of typical capture and non-capture events and characterize the basins of attraction of the equilibrium configurations. Our findings reveal a critical dependence of the hydrodynamic capture mechanism on the external flow intensity. Through adjusting the external flow intensity across the stability threshold, we demonstrate that the active particle can capture and release the passive particle in a controllable manner. Such a capture-and-release mechanism is desirable for biomedical applications such as the capture and release of therapeutic payloads by synthetic micro-swimmers in targeted drug delivery.

High-LET particle exposure of Skylab astronauts

International Nuclear Information System (INIS)

Benton, E.V.; Peterson, D.D.; Bailey, J.V.; Parnell, T.

1977-01-01

High-LET particle radiation was registered in nuclear track recording plastic dosimeters worn on the wrists of Skylab astronauts and located in a heavily shielded film vault. The mission-average planar flux of high-LET particles with LET >= 100 keV/micron . tissue has been determined to be 2.7 +- 0.6 particles/cm 2 . day . 2π sr and 0.34 +- 0.4 particles/cm 2 . day . 2π sr, respectively, for the nine astronauts and for the film vault. Comparison of results representative of a wide range of shielding depths reveals that the magnitude and slope of the integral LET spectrum of high-LET particles inside spacecraft are proportional to the amount of shielding. (author)

Insight into particle production mechanisms from angular correlations of identified particles in pp collisions measured by ALICE

CERN Multimedia

CERN. Geneva

2017-01-01

Two-particle angular correlations are a robust tool which provide access to the underlying physics phenomena of particle production in collisions of both protons and heavy ions by studying distributions of particles in pseudorapidity and azimuthal angle difference. The correlation measurement is sensitive to several phenomena, including mini-jets, elliptic flow, Bose-Einstein correlations, resonance decays, conservation laws, which can be separated by selections of momentum, particle type and by analysing the shapes of the correlation structures. In this talk, we report measurements of the correlations of identified particles and their antiparticles (for pions, kaons, protons, and lambdas) at low transverse momenta in pp collisions at sqrt(s) = 7 TeV, recently submitted for publication by the ALICE Collaboration [arXiv:1612.08975]. The analysis reveals differences in particle production between baryons and mesons. The correlation functions for mesons exhibit the expected peak dominated by effects of mini-jet...

DUST PRODUCTION AND PARTICLE ACCELERATION IN SUPERNOVA 1987A REVEALED WITH ALMA

Energy Technology Data Exchange (ETDEWEB)

Indebetouw, R.; Chevalier, R. [Department of Astronomy, University of Virginia, PO Box 400325, Charlottesville, VA 22904 (United States); Matsuura, M.; Barlow, M. J. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Dwek, E. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Zanardo, G. [International Centre for Radio Astronomy Research (ICRAR), University of Western Australia, Crawley, WA 6009 (Australia); Baes, M. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Bouchet, P. [CEA-Saclay, F-91191 Gif-sur-Yvette (France); Burrows, D. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Clayton, G. C. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Fransson, C.; Lundqvist, P. [Department of Astronomy and the Oskar Klein Centre, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden); Gaensler, B. [Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO) (Australia); Kirshner, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Lakićević, M. [Lennard-Jones Laboratories, Keele University, ST5 5BG (United Kingdom); Long, K. S.; Meixner, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Martí-Vidal, I. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden); Marcaide, J. [Universidad de Valencia, C/Dr. Moliner 50, E-46100 Burjassot (Spain); McCray, R., E-mail: remy@virginia.edu [Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, UCB 391, Boulder, CO 80309 (United States); and others

2014-02-10

Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 μm, 870 μm, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 M {sub ☉}). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

Soft particles at a fluid interface

Science.gov (United States)

Mehrabian, Hadi; Harting, Jens; Snoeijer, Jacco H.

2015-11-01

Particles added to a fluid interface can be used as a surface stabilizer in the food, oil and cosmetic industries. As an alternative to rigid particles, it is promising to consider highly deformable particles that can adapt their conformation at the interface. In this study, we compute the shapes of soft elastic particles using molecular dynamics simulations of a cross-linked polymer gel, complemented by continuum calculations based on the linear elasticity. It is shown that the particle shape is not only affected by the Young's modulus of the particle, but also strongly depends on whether the gel is partially or completely wetting the fluid interface. We find that the molecular simulations for the partially wetting case are very accurately described by the continuum theory. By contrast, when the gel is completely wetting the fluid interface the linear theory breaks down and we reveal that molecular details have a strong influence on the equilibrium shape.

Geometry and dynamics of particle emission from strongly deformed nuclei

International Nuclear Information System (INIS)

Aleshin, V.P.

1995-01-01

By using our semiclassical approach to particle evaporation from deformed nuclei, we analyze the heuristic models of particle emission from deformed nuclei which are used in the codes GANES, ALICE, and EVAP. The calculations revealed that the heuristic models are reasonable for particle energy spectra but fail, at large deformations, to describe the angular distributions

Measurements of particle dynamics in slow, dense granular Couette flow

Science.gov (United States)

Mueth, Daniel M.

2003-01-01

Experimental measurements of particle dynamics on the lower surface of a three-dimensional (3D) Couette cell containing monodisperse spheres are reported. The average radial density and velocity profiles are similar to those previously measured within the bulk and on the lower surface of the 3D cell filled with mustard seeds. Observations of the evolution of particle velocities over time reveal distinct motion events, intervals where previously stationary particles move for a short duration before jamming again. The cross correlation between the velocities of two particles at a given distance r from the moving wall reveals a characteristic length scale over which the particles are correlated. The autocorrelation of a single particle’s velocity reveals a characteristic time scale τ, which decreases with increasing distance from the inner moving wall. This may be attributed to the increasing rarity at which the discrete motion events occur and the reduced duration of those events at large r. The relationship between the rms azimuthal velocity fluctuations, δvθ(r), and average shear rate, γ˙(r), was found to be δvθ∝γ˙α with α=0.52±0.04. These observations are compared with other recent experiments and with the modified hydrodynamic model recently introduced by Bocquet et al.

Optimation of particle size and composition in fabrication of granite particle composite floortiles

International Nuclear Information System (INIS)

Budiarto; Parikin; Mohammad-Dani

2004-01-01

Granite particle composite floortile materials, that have epoxy matrix, may be utilized as water resist and ductile materials. The utility of composite materials for industrial households is, however, very important and very promising indeed. Starting from powdering the granite refuges into particles of 100, 140 and 200 in mesh, the powder was mixed by epoxy containing versamid hardener and stirred till highly homogenized. Specimens were mould in glass frame and dried in ambient temperature for 48 hours. The specimens were prepared into certain dimensions, conformed to testing needs: hardness, density, compression and bending. The hardness and density data show clearly the value change of particulate composition (34, 40, 50 and 70) and matrix (66, 60, 50 and 30) as well. From bending and compression tests, the optimum grain size (μm) and composition (%) of granite particles reveal between the number of 120-123 and 55-61 respectively. The accurate point of the values can be determined by using differential method. As conclusion, for the better mechanical properties of granite particles composite floortiles, the grains should be 121 in μm and 57% composition of granite particles

Mixing state of particles with secondary species by single particle aerosol mass spectrometer in an atmospheric pollution event

Science.gov (United States)

Xu, Lingling; Chen, Jinsheng

2016-04-01

Single particle aerosol mass spectrometer (SPAMS) was used to characterize size distribution, chemical composition, and mixing state of particles in an atmospheric pollution event during 20 Oct. - 5 Nov., 2015 in Xiamen, Southeast China. A total of 533,012 particle mass spectra were obtained and clustered into six groups, comprising of industry metal (4.5%), dust particles (2.6%), carbonaceous species (70.7%), K-Rich particles (20.7%), seasalt (0.6%) and other particles (0.9%). Carbonaceous species were further divided into EC (70.6%), OC (28.5%), and mixed ECOC (0.9%). There were 61.7%, 58.3%, 4.0%, and 14.6% of particles internally mixed with sulfate, nitrate, ammonium and C2H3O, respectively, indicating that these particles had undergone significant aging processing. Sulfate was preferentially mixed with carbonaceous particles, while nitrate tended to mix with metal-containing and dust particles. Compared to clear days, the fractions of EC-, metal- and dust particles remarkably increased, while the fraction of OC-containing particles decreased in pollution days. The mixing state of particles, excepted for OC-containing particles with secondary species was much stronger in pollution days than that in clear days, which revealed the significant influence of secondary particles in atmospheric pollution. The different activity of OC-containing particles might be related to their much smaller aerodynamic diameter. These results could improve our understanding of aerosol characteristics and could be helpful to further investigate the atmospheric process of particles.

PHYSICS, SCIENCE POLICY CERN's seven-point strategy for future particle physics

CERN Multimedia

2004-01-01

Better coordinated particle accelerator research, with more powerful technology, are major priorities on the seven-point "to do list" revealed last week by CERN, the world's largest particle physics laboratory

Differences Research of Particles between Line Smoke and Lampblack

Directory of Open Access Journals (Sweden)

Zhang Cailin

2016-01-01

Full Text Available In this paper, differences of the particle size between the pine smoke powders and lampblack powders were studied. The results showed that the particle spectrum of the pine smoke powders was unimodal distribution, while it was bimodal for the tung lampblack powders. The average particle size, volume of lampblack powders were about 1/3 and 3% of the pine smoke powders, respectively. But the specific surface area of lampblack particles was 5 times more than the pine smoke particles, which revealed the fact that the lampblack powders were more exquisite than the pine smoke powders .

Scattering of particles with internal degrees of freedom

International Nuclear Information System (INIS)

Slipushenko, S. V.; Tur, A. V.; Yanovsky, V. V.

2013-01-01

The scattering of particles with a small number of internal degrees of freedom is considered. Billiard formalism is used to study the scattering of two such structurally complex particles. The main scattering characteristics are found. Various types of scattering modes are revealed. In particular, a mode is detected when the velocity of motion of such particles away from each other is higher than their approach velocity before the collision. The scattering of such particles is shown to occur after a finite number of collisions. A generalized Newton law is proposed for the collision of particles with a small number of degrees of freedom, and the form of the effective coefficient of restitution is found

Fractionation of HeLa cell nuclear extracts reveals minor small nuclear ribonucleoprotein particles

International Nuclear Information System (INIS)

Kroemer, A.

1987-01-01

Upon chromatographic fractionation of HeLa cell nuclear extracts, small RNAs of 145 and 66/65 nucleotides, respectively, were detected that are distinct from the abundant small RNAs present in the extract. These RNAs are precipitated by antibodies directed against the trimethylguanosine cap structure, characteristic for small nuclear RNAs (snRNAs) of the U type. The RNAs of 145 and 66/65 nucleotides appear to be associated with at least one of the proteins common to the major small nuclear ribonucleoprotein particles U1 to U6, since they are specifically bound by anti-Sm antibodies. These criteria characterize the RNAs that are 145 and 66/65 nucleotides in length as U-type snRNAs. Upon gel filtration, the RNAs are found within particles of molecular weights ≅ 150,000 and 115,000 respectively. The RNA of 145 nucleotides represents a different minor snRNA, designated U11, whereas the RNA of 66/65 nucleotides may correspond to either mammalian U7 or U10 RNA

Selection Of Suitable Particle Size And Particle Ratio For Japanese Cucumber Cucumis Sativus L. Plants

Directory of Open Access Journals (Sweden)

Galahitigama GAH

2015-08-01

Full Text Available This study was conducted to select the best particle size of coco peat for cucumber nurseries as well as best particle ratio for optimum plant growth and development of cucumber. The experiment was carried out in International Foodstuff Company and Faculty of Agriculture University of Ruhuna Sri Lanka during 2015 to 2016. Under experiment one three types of different particle sizes were used namely fine amp88040.5mm T2 medium 3mm-0.5mm T3 and coarse 4mm T4 with normal coco peat T1 as treatments. Complete Randomized Design CRD used as experimental design with five replicates. Germination percentage number of leaves per seedling seedling height in frequent day intervals was taken as growth parameters. Analysis of variance procedure was applied to analyze the data at 5 probability level. The results revealed that medium size particle media sieve size 0.5mm -3mm of coco peat was the best particle size for cucumber nursery practice when considered the physical and chemical properties of medium particles of coco peat. In the experiment of selecting of suitable particle ratio for cucumber plants the compressed mixture of coco peat particles that contain 70 ww unsieved coco peat 20 ww coarse particles and 10 ww coconut husk chips 5 12mm has given best results for growth performances compared to other treatments and cucumber grown in this mixture has shown maximum growth and yield performances.

The influence of human physical activity and contaminated clothing type on particle resuspension

International Nuclear Information System (INIS)

McDonagh, A.; Byrne, M.A.

2014-01-01

A study was conducted to experimentally quantify the influence of three variables on the level of resuspension of hazardous aerosol particles from clothing. Variables investigated include physical activity level (two levels, low and high), surface type (four different clothing material types), and time i.e. the rate at which particles resuspend. A mixture of three monodisperse tracer-labelled powders, with median diameters of 3, 5, and 10 microns, was used to “contaminate” the samples, and the resuspended particles were analysed in real-time using an Aerodynamic Particle Sizer (APS), and also by Neutron Activation Analysis (NAA). The overall finding was that physical activity resulted in up to 67% of the contamination deposited on clothing being resuspended back into the air. A detailed examination of the influence of physical activity level on resuspension, from NAA, revealed that the average resuspended fraction (RF) of particles at low physical activity was 28 ± 8%, and at high physical activity was 30 ± 7%, while the APS data revealed a tenfold increase in the cumulative mass of airborne particles during high physical activity in comparison to that during low physical activity. The results also suggest that it is not the contaminated clothing's fibre type which influences particle resuspension, but the material's weave pattern (and hence the material's surface texture). Investigation of the time variation in resuspended particle concentrations indicated that the data were separable into two distinct regimes: the first (occurring within the first 1.5 min) having a high, positive rate of change of airborne particle concentration relative to the second regime. The second regime revealed a slower rate of change of particle concentration and remained relatively unchanged for the remainder of each resuspension event. -- Highlights: • Experimental investigation of the resuspension of hazardous particles from clothing. • Influence of human physical activity

Experimental investigation of coarse particle conveying in pipes

Directory of Open Access Journals (Sweden)

Vlasak Pavel

2015-01-01

Full Text Available The advanced knowledge of particle-water mixture flow behaviour is important for safe, reliable, and economical design and operation of the freight pipelines. The effect of the mixture velocity and concentration on the coarse particle – water mixtures flow behaviour was experimentally investigated on an experimental pipe loop of inner diameter D = 100 mm with horizontal, vertical, and inclined pipe sections. Narrow particle size distribution basalt pebbles were used as model of coarse-grained solid particles. The radiometric method was used to measure particle concentration distribution in pipe cross-section. Mixture flow behaviour and particles motion along the pipe invert were studied in a pipe viewing section. The study revealed that the coarse particlewater mixtures in the horizontal and inclined pipe sections were significantly stratified. The particles moved principally in a layer close to the pipe invert. However, for higher and moderate flow velocities the particles moved also in the central part of the pipe cross-section, and particle saltation was found to be dominant mode of particle conveying.

On the time delay between ultra-relativistic particles

Energy Technology Data Exchange (ETDEWEB)

Fleury, Pierre, E-mail: pierre.fleury@uct.ac.za [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa); Department of Physics, University of the Western Cape, Robert Sobukwe Road, Bellville 7535 (South Africa)

2016-09-10

The time delay between the receptions of ultra-relativistic particles emitted simultaneously is a useful observable for both fundamental physics and cosmology. The expression of the delay when the particles travel through an arbitrary spacetime has been derived recently by Fanizza et al., using a particular coordinate system and self-consistent assumptions. The present article shows that this formula enjoys a simple physical interpretation: the relative velocity between two ultra-relativistic particles is constant. This result reveals an interesting kinematical property of general relativity, namely that the tidal forces experienced by ultra-relativistic particles in the direction of their motion are much smaller than those experienced orthogonally to their motion.

On the time delay between ultra-relativistic particles

International Nuclear Information System (INIS)

Fleury, Pierre

2016-01-01

The time delay between the receptions of ultra-relativistic particles emitted simultaneously is a useful observable for both fundamental physics and cosmology. The expression of the delay when the particles travel through an arbitrary spacetime has been derived recently by Fanizza et al., using a particular coordinate system and self-consistent assumptions. The present article shows that this formula enjoys a simple physical interpretation: the relative velocity between two ultra-relativistic particles is constant. This result reveals an interesting kinematical property of general relativity, namely that the tidal forces experienced by ultra-relativistic particles in the direction of their motion are much smaller than those experienced orthogonally to their motion.

Entrapment of dye molecules within submicron silver particles

Energy Technology Data Exchange (ETDEWEB)

Yosef, Itzik; Avnir, David, E-mail: david@chem.ch.huji.ac.il [Hebrew University of Jerusalem, Institute of Chemistry (Israel)

2011-09-15

We describe a method for the preparation of metal-organic composites submicron particles. Specifically, the preparation of silver particle-clusters 150-200 nm in size, doped with an organic dye Congo-red, is reported. The use of sodium citrate coupled with sodium hypophosphite facilitated the formation of these particle-clusters, which were fully characterized by TEM analysis, Zeta potential and size measurements, scanning electron microscopy, UV-Vis measurements, and thermogravimetric analysis. The latter reveals a catalytic action of the metal on the thermal oxidative decomposition of the entrapped dye. The use of these particles to obtain dense thin metallic films was demonstrated by the coating of ITO glass.

Immobilization of pseudorabies virus in porcine tracheal respiratory mucus revealed by single particle tracking.

Directory of Open Access Journals (Sweden)

Xiaoyun Yang

Full Text Available Pseudorabies virus (PRV initially replicates in the porcine upper respiratory tract. It easily invades the mucosae and submucosae for subsequent spread throughout the body via blood vessels and nervous system. In this context, PRV developed ingenious processes to overcome different barriers such as epithelial cells and the basement membrane. Another important but often overlooked barrier is the substantial mucus layer which coats the mucosae. However, little is known about how PRV particles interact with porcine respiratory mucus. We therefore measured the barrier properties of porcine tracheal respiratory mucus, and investigated the mobility of nanoparticles including PRV in this mucus. We developed an in vitro model utilizing single particle tracking microscopy. Firstly, the mucus pore size was evaluated with polyethylene glycol coupled (PEGylated nanoparticles and atomic force microscope. Secondly, the mobility of PRV in porcine tracheal respiratory mucus was examined and compared with that of negative, positive and PEGylated nanoparticles. The pore size of porcine tracheal respiratory mucus ranged from 80 to 1500 nm, with an average diameter of 455±240 nm. PRV (zeta potential: -31.8±1.5 mV experienced a severe obstruction in porcine tracheal respiratory mucus, diffusing 59-fold more slowly than in water. Similarly, the highly negatively (-49.8±0.6 mV and positively (36.7±1.1 mV charged nanoparticles were significantly trapped. In contrast, the nearly neutral, hydrophilic PEGylated nanoparticles (-9.6±0.8 mV diffused rapidly, with the majority of particles moving 50-fold faster than PRV. The mobility of the particles measured was found to be related but not correlated to their surface charge. Furthermore, PEGylated PRV (-13.8±0.9 mV was observed to diffuse 13-fold faster than native PRV. These findings clearly show that the mobility of PRV was significantly hindered in porcine tracheal respiratory mucus, and that the obstruction of PRV

Dynamic analysis of multiple nuclear-coupled boiling channels based on a multi-point reactor model

International Nuclear Information System (INIS)

Lee, J.D.; Pan Chin

2005-01-01

This work investigates the non-linear dynamics and stabilities of a multiple nuclear-coupled boiling channel system based on a multi-point reactor model using the Galerkin nodal approximation method. The nodal approximation method for the multiple boiling channels developed by Lee and Pan [Lee, J.D., Pan, C., 1999. Dynamics of multiple parallel boiling channel systems with forced flows. Nucl. Eng. Des. 192, 31-44] is extended to address the two-phase flow dynamics in the present study. The multi-point reactor model, modified from Uehiro et al. [Uehiro, M., Rao, Y.F., Fukuda, K., 1996. Linear stability analysis on instabilities of in-phase and out-of-phase modes in boiling water reactors. J. Nucl. Sci. Technol. 33, 628-635], is employed to study a multiple-channel system with unequal steady-state neutron density distribution. Stability maps, non-linear dynamics and effects of major parameters on the multiple nuclear-coupled boiling channel system subject to a constant total flow rate are examined. This study finds that the void-reactivity feedback and neutron interactions among subcores are coupled and their competing effects may influence the system stability under different operating conditions. For those cases with strong neutron interaction conditions, by strengthening the void-reactivity feedback, the nuclear-coupled effect on the non-linear dynamics may induce two unstable oscillation modes, the supercritical Hopf bifurcation and the subcritical Hopf bifurcation. Moreover, for those cases with weak neutron interactions, by quadrupling the void-reactivity feedback coefficient, period-doubling and complex chaotic oscillations may appear in a three-channel system under some specific operating conditions. A unique type of complex chaotic attractor may evolve from the Rossler attractor because of the coupled channel-to-channel thermal-hydraulic and subcore-to-subcore neutron interactions. Such a complex chaotic attractor has the imbedding dimension of 5 and the

Pulling cylindrical particles using a soft-nonparaxial tractor beam

DEFF Research Database (Denmark)

Novitsky, Andrey; Ding, Weiqiang; Wang, Maoyan

2017-01-01

In order to pull objects towards the light source a single tractor beam inevitably needs to be strongly nonparaxial. This stringent requirement makes such a tractor beam somewhat hypothetical. Here we reveal that the cylindrical shape of dielectric particles can effectively mitigate the nonparaxi......In order to pull objects towards the light source a single tractor beam inevitably needs to be strongly nonparaxial. This stringent requirement makes such a tractor beam somewhat hypothetical. Here we reveal that the cylindrical shape of dielectric particles can effectively mitigate...... the nonparaxiality requirements, reducing the incidence angle of the partial plane waves of the light beam down to 45 degrees and even to 30 degrees for respectively dipole and dipole-quadrupole objects. The optical pulling force attributed to the interaction of magnetic dipole and magnetic quadrupole moments...... and sorting of targeted particles....

Bacterial Preferences for Specific Soil Particle Size Fractions Revealed by Community Analyses

DEFF Research Database (Denmark)

Hemkemeyer, Michael; Dohrmann, Anja B.; Christensen, Bent Tolstrup

2018-01-01

Genetic fingerprinting demonstrated in previous studies that differently sized soil particle fractions (PSFs; clay, silt, and sand with particulate organic matter (POM)) harbor microbial communities that differ in structure, functional potentials and sensitivity to environmental conditions....... To elucidate whether specific bacterial or archaeal taxa exhibit preference for specific PSFs, we examined the diversity of PCR-amplified 16S rRNA genes by high-throughput sequencing using total DNA extracted from three long-term fertilization variants (unfertilized, fertilized with minerals, and fertilized...

High energy particle collisions near black holes

Directory of Open Access Journals (Sweden)

Zaslavskii O. B.

2016-01-01

Full Text Available If two geodesic particles collide near a rotating black hole, their energy in the centre of mass frame Ec.m. can become unbound under certain conditions (the so-called BSW effect. The special role is played here by so-called critical geodesics when one of particles has fine-tuned energy and angular momentum. The nature of geodesics reveals itself also in fate of the debris after collisions. One of particles moving to a remote observer is necessarily near-critical. We discuss, when such a collision can give rise not only unboud Ec.m. but also unbound Killing energy E (so-called super-Penrose process.

Fine particles in the Soufriere eruption plume

Science.gov (United States)

Woods, D. C.; Chuan, R. L.

1982-01-01

The size distributions of fine particles measured at tropospheric altitudes in the periphery of the eruption plume formed during the April 17, 1979 eruption of Soufriere Volcano and in the low-level effluents on May 15, 1979 were found to be bimodal, having peak concentrations at geometric mean diameters of 1.1 and 0.23 micrometers. Scanning electron microscopy and energy-dispersive X-ray analysis of the samples revealed an abundance of aluminum and silicon and traces of sodium, magnesium, chlorine, potassium, calcium, and iron in the large-particle mode. The submicrometer-sized particles were covered with liquid containing sulfur, assumed to be in the form of liquid sulfuric acid.

Timeline for particle collider in doubt

CERN Multimedia

Klapper, Bradley S

2007-01-01

"The world's most ambitious particle collider - which scientists hope could reveal what matter is made of - might not be fully functional until next year, months after its scheduled startup date, officiels at the European Organization for Nuclear Reserach said Thursday." (1 page)

Irradiation behaviors of coated fuel particles, (4)

International Nuclear Information System (INIS)

Fukuda, Kousaku; Kashimura, Satoru; Ogawa, Toru; Ikawa, Katsuichi; Iwamoto, Kazumi; Ishimoto, Kiyoshi

1981-09-01

Loose coated fuel particles prepared in confirmity to a preliminary design for the multi-purpose VHTR in fiscal 1972 - 1974 were irradiated by 73F - 12A capsule in JMTR. Main purpose for this irradiation experiment was to examine irradiation stability of the candidate TRISO coated fuel particles for the VHTR. Also the coated particles possessing low-density kernel (90%TD), highly anisotropic OLTI-PyC and ZrC coating layer were loaded with the candidate particles in this capsule. The coated particles were irradiated up to 1.5 x 10 21 n/cm 2 of fast neutron fluence (E > 0.18 MeV) and 3.2% FIMA of burnup. In the post irradiation examination it was observed that among three kinds of TRISO particles exposed to irradiation corresponding to the normal operating condition of the VHTR ones possessing poor characteristics of the coating layers did not show a good stability. The particles irradiated under abnormally high temperature condition (> 1800 0 C) revealed 6.7% of max. EOL failure fraction (95% confidence limit). Most of these particles were failed by the ameoba effect. Furthermore, among four kinds of the TRISO particles exposed to irradiation corresponding to the transient condition of the VHTR (--1500 0 C) the two showed a good stability, while the particles possessing highly anisotropic OLTI-PyC or poorly characteristic coating layers were not so good. (author)

Your ParticleQuest, should you choose to accept it…

CERN Multimedia

Katarina Anthony

2012-01-01

The CERN-developed ParticleQuest adventure game was the focus of a special hands-on session at last month’s Mozilla Festival in London. Attended by the best and the brightest of the coding community, the festival was an opportunity for the ParticleQuest developers to throw down the gaming gauntlet…   Photon and Gluon ParticleQuest sprites. Source: André-Pierre Olivier. A team of CERN students developed the ParticleQuest game during this year’s CERN Summer Student Webfest. What started as simple derivative software of BrowserQuest – one of the first entirely browser-based games developed by the Mozilla Foundation – soon revealed new opportunities to educate players about particle physics. By changing the graphics, introducing a Particle Zoo designed by web designer André-Pierre Olivier and enhancing the game engine, the summer students were convinced that ParticleQuest could help to teach particle physics in a much more ...

Mapping chaos in particle revolutions

International Nuclear Information System (INIS)

Robinson, Arthur L.

2000-01-01

The relatively new technique of frequency map analysis has over the last 10 years turned out to be very effective for the analysis of numerical simulations in physical systems ranging even beyond the solar system to galaxies and back again to particle accelerators, particularly for systems with three or more degrees of freedom. More recently, with an eye towards revealing the dynamics of an actual particle beam, it has been applied for the first time to measured rather than simulated electron trajectories in a storage ring, in this case at the Advanced Light Source (ALS) at the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley Lab)

Single Particle Tracking reveals two distinct environments for CD4 receptors at the surface of living T lymphocytes

International Nuclear Information System (INIS)

Mascalchi, Patrice; Lamort, Anne Sophie; Salomé, Laurence; Dumas, Fabrice

2012-01-01

Highlights: ► We studied the diffusion of single CD4 receptors on living lymphocytes. ► This study reveals that CD4 receptors have either a random or confined diffusion. ► The dynamics of unconfined CD4 receptors was accelerated by a temperature raise. ► The dynamics of confined CD4 receptors was unchanged by a temperature raise. ► Our results suggest the existence of two different environments for CD4 receptors. -- Abstract: We investigated the lateral diffusion of the HIV receptor CD4 at the surface of T lymphocytes at 20 °C and 37 °C by Single Particle Tracking using Quantum Dots. We found that the receptors presented two major distinct behaviors that were not equally affected by temperature changes. About half of the receptors showed a random diffusion with a diffusion coefficient increasing upon raising the temperature. The other half of the receptors was permanently or transiently confined with unchanged dynamics on raising the temperature. These observations suggest that two distinct subpopulations of CD4 receptors with different environments are present at the surface of living T lymphocytes.

Gravitational settling of a highly concentrated system of solid spherical particles

Science.gov (United States)

Arkhipov, V. A.; Usanina, A. S.

2017-09-01

In the present paper, we report on the results of an experimental study of the process of gravity sedimentation of a cloud of monodispersed solid spherical particles with initial volume concentration C > 0.03, which was performed in a wide range of Reynolds numbers. An analytical estimate of the settling regimes of spherical particle clouds is presented. A new method for creating a spherical particle cloud with a high concentration of particles is proposed. A qualitative picture of the settling process of a highly concentrated particle cloud under gravity is revealed. A criterial dependence for the drag coefficient of a sedimenting spherical particle cloud as an entity is obtained.

The influence of human physical activity and contaminated clothing type on particle resuspension.

Science.gov (United States)

McDonagh, A; Byrne, M A

2014-01-01

A study was conducted to experimentally quantify the influence of three variables on the level of resuspension of hazardous aerosol particles from clothing. Variables investigated include physical activity level (two levels, low and high), surface type (four different clothing material types), and time i.e. the rate at which particles resuspend. A mixture of three monodisperse tracer-labelled powders, with median diameters of 3, 5, and 10 microns, was used to "contaminate" the samples, and the resuspended particles were analysed in real-time using an Aerodynamic Particle Sizer (APS), and also by Neutron Activation Analysis (NAA). The overall finding was that physical activity resulted in up to 67% of the contamination deposited on clothing being resuspended back into the air. A detailed examination of the influence of physical activity level on resuspension, from NAA, revealed that the average resuspended fraction (RF) of particles at low physical activity was 28 ± 8%, and at high physical activity was 30 ± 7%, while the APS data revealed a tenfold increase in the cumulative mass of airborne particles during high physical activity in comparison to that during low physical activity. The results also suggest that it is not the contaminated clothing's fibre type which influences particle resuspension, but the material's weave pattern (and hence the material's surface texture). Investigation of the time variation in resuspended particle concentrations indicated that the data were separable into two distinct regimes: the first (occurring within the first 1.5 min) having a high, positive rate of change of airborne particle concentration relative to the second regime. The second regime revealed a slower rate of change of particle concentration and remained relatively unchanged for the remainder of each resuspension event. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evidence for α-particle condensation in nuclei from the Hoyle state deexcitation

International Nuclear Information System (INIS)

Raduta, Ad.R.; Borderie, B.; Geraci, E.; Le Neindre, N.; Napolitani, P.; Rivet, M.F.; Alba, R.; Amorini, F.; Cardella, G.; Chatterjee, M.; De Filippo, E.; Guinet, D.; Lautesse, P.; La Guidara, E.; Lanzalone, G.; Lanzano, G.; Lombardo, I.; Lopez, O.; Maiolino, C.; Pagano, A.

2011-01-01

The fragmentation of quasi-projectiles from the nuclear reaction 40 Ca + 12 C at 25 MeV/nucleon was used to produce excited states candidates to α-particle condensation. Complete kinematic characterization of individual decay events, made possible by a high-granularity 4π charged particle multi-detector, reveals that 7.5±4.0% of the particle decays of the Hoyle state correspond to direct decays in three equal-energy α-particles.

1212-IJBCS-Article-Ovono Abesselo Félix +

African Journals Online (AJOL)

hp

1 nov. 2009 ... prélèvement de sang artériel du cordon a servi au dosage des lactates. La concentration moyenne de lactates était de 3,6±1,8 .... tube hépariné. Les prélèvements ont ensuite été acheminés au laboratoire où le plasma ..... between blood lactate levels, sequential organ failure assessment subcores and 28-.

Examining Model Atmospheric Particles Inside and Out

Science.gov (United States)

Wingen, L. M.; Zhao, Y.; Fairhurst, M. C.; Perraud, V. M.; Ezell, M. J.; Finlayson-Pitts, B. J.

2017-12-01

Atmospheric particles scatter incoming solar radiation and act as cloud condensation nuclei (CCN), thereby directly and indirectly affecting the earth's radiative balance and reducing visibility. These atmospheric particles may not be uniform in composition. Differences in the composition of a particle's outer surface from its core can arise during particle growth, (photo)chemical aging, and exchange of species with the gas phase. The nature of the surface on a molecular level is expected to impact growth mechanisms as well as their ability to act as CCN. Model laboratory particle systems are explored using direct analysis in real time-mass spectrometry (DART-MS), which is sensitive to surface composition, and contrasted with average composition measurements using high resolution, time-of-flight aerosol mass spectrometry (HR-ToF-AMS). Results include studies of the heterogeneous reactions of amines with solid dicarboxylic acid particles, which are shown to generate aminium dicarboxylate salts at the particle surface, leaving an unreacted core. Combination of both mass spectrometric techniques reveals a trend in reactivity of C3-C7 dicarboxylic acids with amines and allows calculation of the DART probe depth into the particles. The results of studies on additional model systems that are currently being explored will also be reported.

Particle size studies to reveal crystallization mechanisms of the metal organic framework HKUST-1 during sonochemical synthesis.

Science.gov (United States)

Armstrong, Mitchell R; Senthilnathan, Sethuraman; Balzer, Christopher J; Shan, Bohan; Chen, Liang; Mu, Bin

2017-01-01

Systematic studies of key operating parameters for the sonochemical synthesis of the metal organic framework (MOF) HKUST-1(also called CuBTC) were performed including reaction time, reactor volume, sonication amplitude, sonication tip size, solvent composition, and reactant concentrations analyzed through SEM particle size analysis. Trends in the particle size and size distributions show reproducible control of average particle sizes between 1 and 4μm. These results along with complementary studies in sonofragmentation and temperature control were conducted to compare these results to kinetic crystal growth models found in literature to develop a plausible hypothetical mechanism for ultrasound-assisted growth of metal-organic-frameworks composed of a competitive mechanism including constructive solid-on-solid (SOS) crystal growth and a deconstructive sonofragmentation. Copyright © 2016 Elsevier B.V. All rights reserved.

Correlative scanning-transmission electron microscopy reveals that a chimeric flavivirus is released as individual particles in secretory vesicles.

Directory of Open Access Journals (Sweden)

Julien Burlaud-Gaillard

Full Text Available The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy. CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations.

Characterization of Makrofol ® DE 1-1 for alpha particle radiography

Science.gov (United States)

El Ghazaly, M.; Aydarous, Abdulkadir; Al-Thomali, Talal A.

2017-09-01

Makrofol ® DE 1-1 (bisphenol-A polycarbonate) was investigated for alpha particle radiography. The edge spread function (ESF) was measured by razor-blade's edge. Makrofol ® DE 1-1 detectors were irradiated with perpendicular incident alpha particles of energy 2.5, 4 and 5.4 MeV, thereafter they were etched in 75% 6N KOH+25% C2H5OH at a temperature of 50 °C for different durations. The etched Makrofol®DE 1-1 detectors were imaged with an optical microscope equipped with a CCD camera. The results revealed that the green channel of the original RGB image provides the highest contrast comparing with red and blue channel by a factor of 27.6% of the original RGB image. The image contrast of alpha particle-irradiated Makrofol®DE 1-1 detector was found to be inversely related to the etching time since the alpha particle tracks proceed from a conical phase to spherical phase. The spatial resolution of alpha particle-irradiated Makrofol®DE 1-1 detector, in terms of line spread function, was found to deteriorate as the etching time increases for all examined alpha particle energies. The results revealed the potential capability of Makrofol®DE 1-1 detector as an efficient detector for alpha particle radiography such as autoradiography.

What is a truly neutral particle?

International Nuclear Information System (INIS)

Tsan, Ung Chan

2004-01-01

An electrically charged particle is necessarily different from its antiparticle while an electrically neutral particle is either identical with or different from its antiparticle. A truly neutral particle is a particle identical to its antiparticle, which means that all its algebraic intrinsic properties are equal to zero since particle and antiparticle have all their algebraic intrinsic properties opposite. We propose two complementary methods to recognize the true nature of any electrically neutral particle. On the one hand, any non-null algebraic intrinsic property of a particle (properties such as Q, magnetic moment already known from classical physics, or quantum numbers such as baryonic number A, lepton number L or flavors, which are meaningful only in the quantum world) reveals that it is distinct from its antiparticle. On the other hand, any particle decaying through a self-conjugate channel or/and through both two conjugate channels is a truly neutral particle implying then that all algebraic intrinsic properties, known or yet unknown, of this particle are null. According to these methods, the neutrino, like any fermion, cannot be its own antiparticle, so neutrinoless double beta decay cannot take place in nature. We point out the internal contradiction required by the existence of hypothetical neutrinoless double beta decay. We suggest that persistent failure to find experimental evidence for this decay mechanism despite huge efforts dedicated to this aim is consistent with the physics of this process. The immediate consequence would be that limits of neutrino mass deduced from neutrinoless double beta decay cannot be used as constraints in contrast with mass limits deduced from the behavior of the end-point in simple beta spectra. (author)

The influence of magnetostatic interactions in exchange-coupled composite particles

DEFF Research Database (Denmark)

Vokoun, D.; Beleggia, Marco; De Graef, M.

2010-01-01

Exchange-coupled composite (ECC) particles are the basic constituents of ECC magnetic recording media. We examine and compare two types of ECC particles: (i) core-shell structures, consisting of a hard-magnetic core and a coaxial soft-magnetic shell and (ii) conventional ECC particles, with a hard-magnetic...... core topped by a soft cylindrical element. The model we present describes the magnetic response of the two ECC particle types, taking into account all significant magnetic contributions to the energy landscape. Special emphasis is given to the magnetostatic (dipolar) interaction energy. We find...... that both the switching fields and the zero-field energy barrier depend strongly on the particle geometry. A comparison between the two types reveals that core-shell ECC particles are more effective in switching field reduction, while conventional ECC particles maintain a larger overall figure of merit....

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)

Hydrodynamic interaction of a self-propelling particle with a wall : Comparison between an active Janus particle and a squirmer model.

Science.gov (United States)

Shen, Zaiyi; Würger, Alois; Lintuvuori, Juho S

2018-03-27

Using lattice Boltzmann simulations we study the hydrodynamics of an active spherical particle near a no-slip wall. We develop a computational model for an active Janus particle, by considering different and independent mobilities on the two hemispheres and compare the behaviour to a standard squirmer model. We show that the topology of the far-field hydrodynamic nature of the active Janus particle is similar to the standard squirmer model, but in the near-field the hydrodynamics differ. In order to study how the near-field effects affect the interaction between the particle and a flat wall, we compare the behaviour of a Janus swimmer and a squirmer near a no-slip surface via extensive numerical simulations. Our results show generally a good agreement between these two models, but they reveal some key differences especially with low magnitudes of the squirming parameter [Formula: see text]. Notably the affinity of the particles to be trapped at a surface is increased for the active Janus particles when compared to standard squirmers. Finally, we find that when the particle is trapped on the surface, the velocity parallel to the surface exceeds the bulk swimming speed and scales linearly with [Formula: see text].

Continuous-flow sheathless diamagnetic particle separation in ferrofluids

International Nuclear Information System (INIS)

Zhou, Yilong; Song, Le; Yu, Liandong; Xuan, Xiangchun

2016-01-01

Separating particles from a complex mixture is often necessary in many chemical and biomedical applications. This work presents a continuous-flow sheathless diamagnetic particle separation in ferrofluids through U-shaped microchannels. Due to the action of a size-dependent magnetic force, diamagnetic particles are focused into a single stream in the inlet branch of the U-turn and then continuously separated into two streams in its outlet branch. A 3D numerical model is developed to predict and understand the diamagnetic particle transport during this separation process. The numerical predictions are found to agree well with the experimental observations in a systematic study of the effects of multiple parameters including ferrofluid flow rate, concentration and magnet-channel distance. Additional numerical studies of the geometric effects of the U-turn reveal that increasing the outlet-branch width of the U-turn can significantly enhance the diamagnetic particle separation in ferrofluids. - Highlights: • Particles are focused and separated in the two branches of a U-shaped microchannel. • Negative magnetophoretic motion in ferrofluids causes the particle deflection. • A 3D numerical model is developed to simulate the particle separation. • Multiple parametric effects are studied both experimentally and numerically. • Increasing the outlet-branch width significantly enhances the particle separation.

Continuous-flow sheathless diamagnetic particle separation in ferrofluids

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yilong [Department of Mechanical Engineering, Clemson University, Clemson, SC 29634-0921 (United States); Song, Le [School of Instrument Science and Opto-electronic Engineering, Hefei University of Technology, Hefei 230009 (China); Yu, Liandong, E-mail: liandongyu@hfut.edu.cn [School of Instrument Science and Opto-electronic Engineering, Hefei University of Technology, Hefei 230009 (China); Xuan, Xiangchun, E-mail: xcxuan@clemson.edu [Department of Mechanical Engineering, Clemson University, Clemson, SC 29634-0921 (United States)

2016-08-15

Separating particles from a complex mixture is often necessary in many chemical and biomedical applications. This work presents a continuous-flow sheathless diamagnetic particle separation in ferrofluids through U-shaped microchannels. Due to the action of a size-dependent magnetic force, diamagnetic particles are focused into a single stream in the inlet branch of the U-turn and then continuously separated into two streams in its outlet branch. A 3D numerical model is developed to predict and understand the diamagnetic particle transport during this separation process. The numerical predictions are found to agree well with the experimental observations in a systematic study of the effects of multiple parameters including ferrofluid flow rate, concentration and magnet-channel distance. Additional numerical studies of the geometric effects of the U-turn reveal that increasing the outlet-branch width of the U-turn can significantly enhance the diamagnetic particle separation in ferrofluids. - Highlights: • Particles are focused and separated in the two branches of a U-shaped microchannel. • Negative magnetophoretic motion in ferrofluids causes the particle deflection. • A 3D numerical model is developed to simulate the particle separation. • Multiple parametric effects are studied both experimentally and numerically. • Increasing the outlet-branch width significantly enhances the particle separation.

The accurate particle tracer code

Science.gov (United States)

Wang, Yulei; Liu, Jian; Qin, Hong; Yu, Zhi; Yao, Yicun

2017-11-01

The Accurate Particle Tracer (APT) code is designed for systematic large-scale applications of geometric algorithms for particle dynamical simulations. Based on a large variety of advanced geometric algorithms, APT possesses long-term numerical accuracy and stability, which are critical for solving multi-scale and nonlinear problems. To provide a flexible and convenient I/O interface, the libraries of Lua and Hdf5 are used. Following a three-step procedure, users can efficiently extend the libraries of electromagnetic configurations, external non-electromagnetic forces, particle pushers, and initialization approaches by use of the extendible module. APT has been used in simulations of key physical problems, such as runaway electrons in tokamaks and energetic particles in Van Allen belt. As an important realization, the APT-SW version has been successfully distributed on the world's fastest computer, the Sunway TaihuLight supercomputer, by supporting master-slave architecture of Sunway many-core processors. Based on large-scale simulations of a runaway beam under parameters of the ITER tokamak, it is revealed that the magnetic ripple field can disperse the pitch-angle distribution significantly and improve the confinement of energetic runaway beam on the same time.

Single particle tracking reveals spatial and dynamic organization of the Escherichia coli biofilm matrix

International Nuclear Information System (INIS)

Birjiniuk, Alona; Doyle, Patrick S; Billings, Nicole; Ribbeck, Katharina; Nance, Elizabeth; Hanes, Justin

2014-01-01

Biofilms are communities of surface-adherent bacteria surrounded by secreted polymers known as the extracellular polymeric substance. Biofilms are harmful in many industries, and thus it is of great interest to understand their mechanical properties and structure to determine ways to destabilize them. By performing single particle tracking with beads of varying surface functionalization it was found that charge interactions play a key role in mediating mobility within biofilms. With a combination of single particle tracking and microrheological concepts, it was found that Escherichia coli biofilms display height dependent charge density that evolves over time. Statistical analyses of bead trajectories and confocal microscopy showed inter-connecting micron scale channels that penetrate throughout the biofilm, which may be important for nutrient transfer through the system. This methodology provides significant insight into a particular biofilm system and can be applied to many others to provide comparisons of biofilm structure. The elucidation of structure provides evidence for the permeability of biofilms to microscale objects, and the ability of a biofilm to mature and change properties over time. (paper)

Particle physics prospects for the KAON factory

International Nuclear Information System (INIS)

Bryman, D.

1989-05-01

The Kaon Factory at TRIUMF will produce beams of kaons, antiprotons, neutrinos and other particles with a hundred-fold increase in intensity over existing machines in the 30 GeV region. This will make possible new high precision experiments designed to test current ideas as well as high sensitivity measurements which could potentially reveal new effects. A sample of particle physics experiments involving rare kaon decays, CP and T violation studies, neutrino properties and reactions and light quark spectroscopy which might take advantage of the new opportunities presented by the Kaon Factory is discussed

Selective particle trapping using an oscillating microbubble.

Science.gov (United States)

Rogers, Priscilla; Neild, Adrian

2011-11-07

The ability to isolate and sort analytes within complex microfluidic volumes is essential to the success of lab-on-a-chip (LOC) devices. In this study, acoustically-excited oscillating bubbles are used to selectively trap particles, with the selectivity being a function of both particle size and density. The operating principle is based on the interplay between the strong microstreaming-induced drag force and the attractive secondary Bjerknes force. Depending upon the size of the bubble, and thus its resonant frequency, it is possible to cause one force to dominate over the other, resulting in either particle attraction or repulsion. A theoretical analysis reveals the extent of the contribution of each force for a given particle size; in close agreement with experimental findings. Density-based trapping is also demonstrated, highlighting that denser particles experience a larger secondary Bjerknes force resulting in their attraction. This study showcases the excellent applicability and versatility of using oscillating bubbles as a trapping and sorting mechanism within LOC devices. This journal is © The Royal Society of Chemistry 2011

Particle metaphysics. A critical account of subatomic reality

International Nuclear Information System (INIS)

Falkenburg, B.

2007-01-01

The empirical successes of atomic, nuclear, and particle physics have not reduced -- and may never fully resolve -- the philosophical controversies about the inner constitution of matter. This book examines these debates by exploring the particle concept in physics. Are the particles of modern physics ''real'' or are they fictitious entities, their existence deduced merely by the careless application of abstract theories? Or are the philosophers involved in the debate about ''scientific realism'' dedicating themselves to a problem that has long been solved by physicists? Studies of the experimental basis and theoretical relevance of the particle concept reveal that these questions are far from easy to answer, because, since the introduction of quantum theory, physical science no longer possesses a single unambiguous particle concept. All those interested in the ''true meaning'' of such physical concepts will find this book informative and thought provoking. It is written at a level accessible to scholars, students and teachers of science and philosophy. (orig.)

The origin of mass elementary particles and fundamental symmetries

CERN Document Server

Iliopoulos, John

2017-01-01

The discovery of a new elementary particle at the Large Hadron Collider at CERN in 2012 made headlines in world media. Since we already know of a large number of elementary particles, why did this latest discovery generate so much excitement? This small book reveals that this particle provides the key to understanding one of the most extraordinary phenomena which occurred in the early Universe. It introduces the mechanism that made possible, within tiny fractions of a second after the Big Bang, the generation of massive particles. The Origin of Mass is a guided tour of cosmic evolution, from the Big Bang to the elementary particles we study in our accelerators today. The guiding principle of this book is a concept of symmetry which, in a profound and fascinating way, seems to determine the structure of the Universe.

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

Improving ATLAS Jet Measurements and Searches with Particle Information

CERN Document Server

Ramette, Joshua; Doglioni, Caterina; Young, Christopher; CERN. Geneva. EP Department

2016-01-01

With the LHC running at record collision energies, the ATLAS detector may reveal new physics including particles decaying hadronically into jets. Measurements involving jets are often limited by the jet energy scale uncertainty associated with the calibration of the detector response to jets in the hadronic calorimeters. In this article we examine the jet energy response dependence upon the fraction of jet energy contained in charged versus neutral particles by running the multijet balance with particle flow jets on a series of charged fraction cuts using both Monte Carlo and data jet samples. We discuss how the results can contribute to a reduction of the jet energy uncertainty for high energy jets where the uncertainty is estimated with the single particle propagation technique.

Tungsten particle reinforced Al 5083 composite with high strength and ductility

Energy Technology Data Exchange (ETDEWEB)

Bauri, Ranjit, E-mail: rbauri@iitm.acin; Yadav, Devinder; Shyam Kumar, C.N.; Balaji, B.

2015-01-03

Tungsten particles were incorporated into an Al 5083 matrix by friction stir processing (FSP). FSP resulted in uniform dispersion of the tungsten particles with excellent interfacial bonding and more importantly without the formation of any harmful intermetallics. For the first time, the particles penetrated to a depth equal to the full pin length of the tool. A novel aspect of the 5083 Al–W composite is that it showed an improvement of more than 100 MPa in the UTS and at the same time exhibited a high ductility (30%). The ductility was also evident from the well defined dimples in the fracture surface which also revealed the superior bonding between the particles and the matrix. FSP also resulted in substantial grain refinement of the Al matrix. Electron backscatter diffraction (EBSD) and transmission electron microscopy analysis revealed that the fine grains formed by dynamic recrystallization. A gradual transformation from sub-grain to high-angle grain boundaries was observed from EBSD analysis pointing towards the occurrence of a continuous type of dynamic recrystallization process.

Pattern formation in annular systems of repulsive particles

International Nuclear Information System (INIS)

Marschler, Christian; Starke, Jens; Sørensen, Mads P.; Gaididei, Yuri B.; Christiansen, Peter L.

2016-01-01

General particle models with symmetric and asymmetric repulsion are studied and investigated for finite-range and exponential interaction in an annulus. In the symmetric case transitions from one- to multi-lane behavior including multistability are observed for varying particle density and for a varying curvature with fixed density. Hence, the system cannot be approximated by a periodic channel. In the asymmetric case, which is important in pedestrian dynamics, we reveal an inhomogeneous new phase, a traveling wave reminiscent of peristaltic motion. - Highlights: • An asymmetrically interacting repulsive particle model is introduced. • Multi-stability is found in a pedestrian dynamics model. • Transitions from one- to multi-lane behavior are studied numerically.

Emissions of soot particles from heat generators

Science.gov (United States)

Lyubov, V. K.; Popov, A. N.; Popova, E. I.

2017-11-01

«Soot carbon» or «Soot» - incomplete combustion or thermal decomposition particulate carbon product of hydrocarbons consisting of particles of various shapes and sizes. Soot particles are harmful substances Class 2 and like a dust dispersed by wind for thousands of kilometers. Soot have more powerful negative factor than carbon dioxide. Therefore, more strict requirements on ecological and economical performance for energy facilities at Arctic areas have to be developed to protect fragile Arctic ecosystems and global climate change from degradation and destruction. Quantity of soot particles in the flue gases of energy facilities is a criterion of effectiveness for organization of the burning process. Some of heat generators do not provide the required energy and environmental efficiency which results in irrational use of energy resources and acute pollution of environment. The paper summarizes the results of experimental study of solid particles emission from wide range of capacity boilers burning different organic fuels (natural gas, fuel oil, coal and biofuels). Special attention is paid to environmental and energy performance of the biofuels combustion. Emissions of soot particles PM2.5 are listed. Structure, composition and dimensions of entrained particles with the use of electronic scanning microscope Zeiss SIGMA VP were also studied. The results reveal an impact of several factors on soot particles emission.

Spatiotemporal Structure of Aeolian Particle Transport on Flat Surface

Science.gov (United States)

Niiya, Hirofumi; Nishimura, Kouichi

2017-05-01

We conduct numerical simulations based on a model of blowing snow to reveal the long-term properties and equilibrium state of aeolian particle transport from 10-5 to 10 m above the flat surface. The numerical results are as follows. (i) Time-series data of particle transport are divided into development, relaxation, and equilibrium phases, which are formed by rapid wind response below 10 cm and gradual wind response above 10 cm. (ii) The particle transport rate at equilibrium is expressed as a power function of friction velocity, and the index of 2.35 implies that most particles are transported by saltation. (iii) The friction velocity below 100 µm remains roughly constant and lower than the fluid threshold at equilibrium. (iv) The mean particle speed above 300 µm is less than the wind speed, whereas that below 300 µm exceeds the wind speed because of descending particles. (v) The particle diameter increases with height in the saltation layer, and the relationship is expressed as a power function. Through comparisons with the previously reported random-flight model, we find a crucial problem that empirical splash functions cannot reproduce particle dynamics at a relatively high wind speed.

Particle size distribution control of Pt particles used for particle gun

Science.gov (United States)

Ichiji, M.; Akiba, H.; Nagao, H.; Hirasawa, I.

2017-07-01

The purpose of this study is particle size distribution (PSD) control of submicron sized Pt particles used for particle gun. In this report, simple reaction crystallization is conducted by mixing H2PtCl6 and ascorbic acid. Without the additive, obtained Pt particles have broad PSD and reproducibility of experiment is low. With seeding, Pt particles have narrow PSD and reproducibility improved. Additionally, mean particle diameter of 100-700 nm is controlled by changing seeding amount. Obtained particles are successfully characterized as Pt by XRD results. Moreover, XRD spectra indicate that obtained particles are polycrystals. These experimental results suggest that seeding consumed nucleation, as most nuclei attached on the seed surface. This mechanism virtually restricted nucleation to have narrow PSD can be obtained.

Pattern formation in annular systems of repulsive particles

DEFF Research Database (Denmark)

Marschler, Christian; Starke, Jens; Sørensen, Mads Peter

2016-01-01

General particle models with symmetric and asymmetric repulsion are studied and investigated for finite-range and exponential interaction in an annulus. In the symmetric case transitions from one- to multi-lane behavior including multistability are observed for varying particle density and for a ...... and for a varying curvature with fixed density. Hence, the system cannot be approximated by a periodic channel. In the asymmetric case, which is important in pedestrian dynamics, we reveal an inhomogeneous new phase, a traveling wave reminiscent of peristaltic motion....

Atom probe characterization of yttria particles in ODS Eurofer steel

International Nuclear Information System (INIS)

Aleev, A.A.; Zaluzhny, A.G.; Nikitin, A.A.; Rogozhkin, S.V.; Iskandarov, N.A.; Vladimirov, P.; Moeslang, A.; Lindau, R.; Klimenkov, M.

2009-01-01

Oxide dispersion strengthened steels exhibit higher temperature and radiation resistance than conventionally produced ferritic/martensitic steels. Such behaviour, as believed, is mainly caused by presence of highly dispersed and extremely stable oxide particles with sizes of few nanometers. It was shown that the most promising oxide additive was yttria (Y 2 O 3 ) and as mechanical parameters were strongly depended on size and number density of formed peculiarities it is required to reduce their dimensions to few nanometers and drastically increase their number. At present, considerable effort is focused on investigation of behaviour and properties of such particles. Recent studies of Eurofer ODS steel (9%-CrWVTa) by SANS and PoAS revealed the presence of high number density structural peculiarities with size approximately one nanometer. At the same time, previous studies by TEM identified only high number of small (5-10 nm) Y 2 O 3 particles. So, the purpose of this work was to look into this material by means of tomographic atom probe and find out the chemistry and origin of peculiarities with sizes less than 5 nm. These investigations revealed fine (∼ 2 nm) particles that were enriched not only in yttrium and oxygen but also in vanadium and nitrogen. Concentration of vanadium in them is approximately at the same level as yttrium. Moreover, some particles were found to be enriched in only three or even two elements mentioned above. However, total concentration of chemical elements in these particles is considerably less than that of iron. Estimated number density for detected particles is (1 / 5) x 10 23 m -3 . (author)

Electron microscopy investigation of spark-eroded Ni-Mn-Ga ferromagnetic shape-memory alloy particles

Energy Technology Data Exchange (ETDEWEB)

Solomon, Virgil C. [School of Materials, Arizona State University, Tempe, AZ 85287 (United States)], E-mail: virgil.solomon@asu.edu; Hong, J.-I. [Center for Magnetic Recording Research, University of California at San Diego, La Jolla, CA 92093 (United States); Tang, Y.J. [Center for Magnetic Recording Research, University of California at San Diego, La Jolla, CA 92093 (United States); Berkowitz, Ami E. [Center for Magnetic Recording Research, University of California at San Diego, La Jolla, CA 92093 (United States); Smith, David J. [School of Materials, Arizona State University, Tempe, AZ 85287 (United States); Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

2007-04-15

The microstructural and chemical characteristics of Ni-Mn-Ga particles produced by spark-erosion using liquid argon or liquid nitrogen dielectrics were investigated by electron microscopy techniques. The particles were predominantly micron-sized spheres; those obtained in argon were solid, whereas those obtained in nitrogen were primarily hollow. The investigation of annealed particles revealed twinned microstructure and provided evidence supporting the cryogen solubility model of hollow particle formation, as well as possibly explaining the non-homogeneous structure of particles formed by spark-erosion in liquid nitrogen.

Nanoparticle electrostatic loss within corona needle charger during particle-charging process

International Nuclear Information System (INIS)

Huang Chenghsiung; Alonso, Manuel

2011-01-01

A numerical investigation has been carried out to examine the electrostatic loss of nanoparticles in a corona needle charger. Two-dimensional flow field, electric field, particle charge, and particle trajectory were simulated to obtain the electrostatic deposition loss at different conditions. Simulation of particle trajectories shows that the number of charges per particle during the charging process depends on the particle diameter, radial position from the symmetry axis, applied voltage, Reynolds number, and axial distance along the charger. The numerical results of nanoparticle electrostatic loss agreed fairly well with available experimental data. The results reveal that the electrostatic loss of nanoparticles increases with increasing applied voltage and electrical mobility of particles; and with decreasing particle diameter and Reynolds number. A regression equation closely fitted the obtained numerical results for different conditions. The equation is useful for directly calculating the electrostatic loss of nanoparticles in the corona needle charger during particle-charging process.

Health impact of exposure to fine particles. Epidemiology of short-term effects

International Nuclear Information System (INIS)

Peters, Annette; Wichmann, H.-Erich; Univ. Muenchen; Heinrich, Joachim

2002-01-01

Epidemiological studies on short-term effects of fine particles are investigating whether morbidity or mortality increase on days with high particle concentrations. Multi-center studies have shown on a daily basis that there is an increase in morbidity and/or mortality in association with particle concentrations. Studies on the effects of particles on the respiratory tract have indicated that there is an impact of particles at their place of deposition. In addition, numerous studies have revealed that particles also have effects on the cardiovascular system, including acute-phase reactions, increased hospital admissions, and also an increase in cardiovascular disease mortality in association with elevated particle concentrations. For PM 10 consistent effects were found. Furthermore, the analyses showed that no threshold value could be established, but a linear dose-effect relation. Studies measuring PM 2.5 point to fine particles being mainly responsible for these effects. Current studies show that in addition to fine particles, ultra-fine particles can cause further health effects. (orig.) [de

Modeling Evaporation and Particle Assembly in Colloidal Droplets.

Science.gov (United States)

Zhao, Mingfei; Yong, Xin

2017-06-13

Evaporation-induced assembly of nanoparticles in a drying droplet is of great importance in many engineering applications, including printing, coating, and thin film processing. The investigation of particle dynamics in evaporating droplets can provide fundamental hydrodynamic insight for revealing the processing-structure relationship in the particle self-organization induced by solvent evaporation. We develop a free-energy-based multiphase lattice Boltzmann method coupled with Brownian dynamics to simulate evaporating colloidal droplets on solid substrates with specified wetting properties. The influence of interface-bound nanoparticles on the surface tension and evaporation of a flat liquid-vapor interface is first quantified. The results indicate that the particles at the interface reduce surface tension and enhance evaporation flux. For evaporating particle-covered droplets on substrates with different wetting properties, we characterize the increase of evaporate rate via measuring droplet volume. We find that droplet evaporation is determined by the number density and circumferential distribution of interfacial particles. We further correlate particle dynamics and assembly to the evaporation-induced convection in the bulk and on the surface of droplet. Finally, we observe distinct final deposits from evaporating colloidal droplets with bulk-dispersed and interface-bound particles. In addition, the deposit pattern is also influenced by the equilibrium contact angle of droplet.

Micromagnetic simulations of spinel ferrite particles

International Nuclear Information System (INIS)

Dantas, Christine C.; Gama, Adriana M.

2010-01-01

This paper presents the results of simulations of the magnetization field ac response (at 2-12 GHz) of various submicron ferrite particles (cylindrical dots). The ferrites in the present simulations have the spinel structure, expressed here by M 1 - n Zn n Fe 2 O 4 (where M stands for a divalent metal), and the parameters chosen were the following: (a) for n=0: M={Fe, Mn, Co, Ni, Mg, Cu }; (b) for n=0.1: M = {Fe, Mg} (mixed ferrites). These runs represent full 3D micromagnetic (one-particle) ferrite simulations. We find evidences of confined spin waves in all simulations, as well as a complex behavior nearby the main resonance peak in the case of the M = {Mg, Cu} ferrites. A comparison of the n=0 and n=0.1 cases for fixed M reveals a significant change in the spectra in M = Mg ferrites, but only a minor change in the M=Fe case. An additional larger scale simulation of a 3 by 3 particle array was performed using similar conditions of the Fe 3 O 4 (magnetite; n=0, M = Fe) one-particle simulation. We find that the main resonance peak of the Fe 3 O 4 one-particle simulation is disfigured in the corresponding 3 by 3 particle simulation, indicating the extent to which dipolar interactions are able to affect the main resonance peak in that magnetic compound.

Source characterization of urban particles from meat smoking activities in Chongqing, China using single particle aerosol mass spectrometry.

Science.gov (United States)

Chen, Yang; Wenger, John C; Yang, Fumo; Cao, Junji; Huang, Rujin; Shi, Guangming; Zhang, Shumin; Tian, Mi; Wang, Huanbo

2017-09-01

A Single Particle Aerosol Mass Spectrometer (SPAMS) was deployed in the urban area of Chongqing to characterize the particles present during a severe particulate pollution event that occurred in winter 2014-2015. The measurements were made at a time when residents engaged in traditional outdoor meat smoking activities to preserve meat before the Chinese Spring Festival. The measurement period was predominantly characterized by stagnant weather conditions, highly elevated levels of PM 2.5 , and low visibility. Eleven major single particle types were identified, with over 92.5% of the particles attributed to biomass burning emissions. Most of the particle types showed appreciable signs of aging in the stagnant air conditions. To simulate the meat smoking activities, a series of controlled smoldering experiments was conducted using freshly cut pine and cypress branches, both with and without wood logs. SPAMS data obtained from these experiments revealed a number of biomass burning particle types, including an elemental and organic carbon (ECOC) type that proved to be the most suitable marker for meat smoking activities. The traditional activity of making preserved meat in southwestern China is shown here to be a major source of particulate pollution. Improved measures to reduce emissions from the smoking of meat should be introduced to improve air quality in regions where smoking meat activity prevails. Copyright © 2017 Elsevier Ltd. All rights reserved.

Index of refraction enhancement of calcite particles coated with zinc carbonate

Science.gov (United States)

Lattaud, Kathleen; Vilminot, Serge; Hirlimann, Charles; Parant, Hubert; Schoelkopf, Joachim; Gane, Patrick

2006-10-01

ZnCO 3 coating on calcite particles has been developed in order to enhance the index of refraction of this mineral that is used as a charge in paper, paint and polymer industries. Chemical reaction between calcite particles in an aqueous suspension with zinc chloride promotes the formation of a ZnCO 3 coating consisting of two layers with different interactions with the calcite particle. The refraction index of the resulting composite particles increases with the Zn/Ca ratio. A model allows to evaluate the coating thickness. The value of the scattering S and diffusion K coefficients of sheets coated with the ZnCO 3 coated particles reveal a dependence on the preparation conditions with a 15% increase for the best samples.

First passage times for multiple particles with reversible target-binding kinetics

Science.gov (United States)

Grebenkov, Denis S.

2017-10-01

We investigate the first passage problem for multiple particles that diffuse towards a target, partially adsorb there, and then desorb after a finite exponentially distributed residence time. We search for the first time when m particles undergoing such reversible target-binding kinetics are found simultaneously on the target that may trigger an irreversible chemical reaction or a biophysical event. Even if the particles are independent, the finite residence time on the target yields an intricate temporal coupling between particles. We compute analytically the mean first passage time (MFPT) for two independent particles by mapping the original problem to higher-dimensional surface-mediated diffusion and solving the coupled partial differential equations. The respective effects of the adsorption and desorption rates on the MFPT are revealed and discussed.

Particle Physics at the LHC Start

CERN Document Server

Altarelli, Guido

2011-01-01

I present a concise review of the major issues and challenges in particle physics at the start of the LHC era. After a brief overview of the Standard Model and of QCD, I will focus on the electroweak symmetry breaking problem which plays a central role in particle physics today. The Higgs sector of the minimal Standard Model is so far just a mere conjecture that needs to be verified or discarded by the LHC. Probably the reality is more complicated. I will summarize the motivation for new physics that should accompany or even replace the Higgs discovery and a number of its possible forms that could be revealed by the LHC.

Hot-melt extrusion for enhanced delivery of drug particles.

Science.gov (United States)

Miller, Dave A; McConville, Jason T; Yang, Wei; Williams, Robert O; McGinity, James W

2007-02-01

With the recent advent of nanotechnology for pharmaceutical applications, drug particle engineering is the focus of increasing interest as a viable approach for overcoming solubility limitations of poorly water-soluble drugs. Although these particle engineering techniques have been proven successful for enhancing the dissolution properties of many poorly water-soluble drugs, there are limitations associated with them such as particle aggregation, morphological instability, and poor wettability. The aim of this study was to demonstrate a processing technique in which hot-melt extrusion (HME) is utilized to overcome these limitations. Micronized particles of amorphous itraconazole (ITZ) stabilized with PVP or HPMC were produced and subsequently melt extruded with poloxamer 407 and PEO 200 M to deaggregate and disperse the particles into the hydrophilic polymer matrix. Differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy were used to demonstrate that the HME process did not alter the properties of the micronized particles. Dissolution testing conducted at sink conditions revealed that the dissolution rate of the micronized particles was improved by HME due to particle deaggregation and enhanced wetting. Supersaturation dissolution testing demonstrated that the ITZ-HPMC micronized particle extrudates provided superior supersaturation of ITZ compared to the ITZ-PVP micronized particle extrudates. Supersaturation dissolution testing incorporating a pH change (from pH 1.2 to 6.8 at 2 h) revealed that neither micronized particle extrudate formulation significantly reduced the rate of ITZ precipitation from supersaturated solution once pH was increased. Moreover, the two extrudate formulations performed very similarly when only considering dissolution testing from just before pH adjustment through the duration of testing at neutral pH. From oral dosing of rats, it was determined that the two extrudate formulations performed similarly in

Particle production in high energy nucleus-nucleus collisions

International Nuclear Information System (INIS)

Stock, R.

1985-05-01

Recent data on the production of pions and strange particles at the Bevalac and Synchrophasotron accelerators are reviewed, covering pion spectra and multiplicity distributions, Λ, K + and K - yields and spectra, and Λ polarization. Emphasis is placed on recent progress in determining the equation of state of compressed fireball nuclear matter from the observed pion yield in central collisions. Further, the information derived from apparent spectral temperatures is critically examined, along with a discussion of thermal and chemical equilibrium attainment in the reactions, as revealed by particle spectra and yields. (orig.)

Particle metaphysics. A critical account of subatomic reality

Energy Technology Data Exchange (ETDEWEB)

Falkenburg, B. [Dortmund Univ. (Germany). Inst. fuer Philosophie

2007-07-01

The empirical successes of atomic, nuclear, and particle physics have not reduced -- and may never fully resolve -- the philosophical controversies about the inner constitution of matter. This book examines these debates by exploring the particle concept in physics. Are the particles of modern physics ''real'' or are they fictitious entities, their existence deduced merely by the careless application of abstract theories? Or are the philosophers involved in the debate about ''scientific realism'' dedicating themselves to a problem that has long been solved by physicists? Studies of the experimental basis and theoretical relevance of the particle concept reveal that these questions are far from easy to answer, because, since the introduction of quantum theory, physical science no longer possesses a single unambiguous particle concept. All those interested in the ''true meaning'' of such physical concepts will find this book informative and thought provoking. It is written at a level accessible to scholars, students and teachers of science and philosophy. (orig.)

Nuclear physics with strange particles

International Nuclear Information System (INIS)

Dover, C.B.

1988-01-01

Recent progress in the understanding of strange particle interactions with nuclear systems is reviewed. We discuss the relative merits of various reactions such as (K - , π/sup +-/), (π + , K + ), or (γ, K + ) for hypernuclear production. The structure of /sub Λ/ 13 C is analyzed in some detail, in order to illustrate the role of the ΛN residual interaction and approximate dynamical symmetries in hypernuclear structure. Recent results on the single particle states of a Λ in heavy systems, as revealed by (π + , K + ) reaction studies, are used to extract information on the density dependence and effective mass which characterize the Λ-nucleus mean field. Finally, we develop the idea the K + -nucleus scattering at low energies is sensitive to the subtle ''swelling'' effects for nucleons bound in nuclei. 64 refs., 13 figs

Heterogeneous reactivity of sea spray particles during the CalNex field campaign: Insight from single particle measurements and correlations with gas phase measurements

Science.gov (United States)

Gaston, C. J.; Riedel, T. P.; Thornton, J. A.; Wagner, N.; Brown, S. S.; Quinn, P.; Bates, T. S.; Prather, K. A.

2011-12-01

Sea spray particles are ubiquitous in marine environments. Heterogeneous reactions between sea spray particles and gas phase pollutants, such as HNO3(g), and N2O5(g), alter particle composition by displacing particulate phase halogens in sea spray and releasing these halogen species into the gas phase; these halogen-containing gas phase species play a significant role in tropospheric ozone production. Measurements of both gas phase and particle phase species on board the R/V Atlantis during the CalNEX 2010 field campaign provided an opportunity to examine the impact of heterogeneous reactivity of marine aerosols along the California coast. During the cruise, coastal measurements were made near the Santa Monica and Port of Los Angeles regions to monitor the chemical processing of marine aerosols. Sea spray particles were analyzed since these particles were the major chloride-containing particles detected. Real-time single particle measurements made using an aerosol time-of-flight mass spectrometer (ATOFMS) revealed the nocturnal processing of sea spray particles through the loss of particulate chloride and a simultaneous gain in particulate nitrate. Gas phase measurements are consistent with the particle phase observations: As N2O5(g) levels rose overnight, the production of ClNO2(g) coincided with the decrease in particulate chloride. These observations provide unique insight into heterogeneous reactivity from both a gas and particle phase perspective. Results from these measurements can be used to better constrain the rate of heterogeneous reactions on sea spray particles.

Irradiation of single cells with individual high-LET particles

International Nuclear Information System (INIS)

Nelson, J.M.; Braby, L.A.

1993-01-01

The dose-limiting normal tissue of concern when irradiating head and neck lesions is often the vascular endothelium within the treatment field. Consequently, the response of capillary endothelial cells exposed to moderate doses of high LET particles is essential for establishing exposure limits for neutron-capture therapy. In an effort to characterize the high-LET radiation biology of cultured endothelial cells, the authors are attempting to measure cellular response to single particles. The single-particle irradiation apparatus, described below, allows them to expose individual cells to known numbers of high-LET particles and follow these cells for extended periods, in order to assess the impact of individual particles on cell growth kinetics. Preliminary cell irradiation experiments have revealed complications related to the smooth and efficient operation of the equipment; these are being resolved. Therefore, the following paragraphs deal primarily with the manner by which high LET particles deposit energy, the requirements for single-cell irradiation, construction and assembly of such apparatus, and testing of experimental procedures, rather than with the radiation biology of endothelial cells

Dynamic forces on agglomerated particles caused by high-intensity ultrasound.

Science.gov (United States)

Knoop, Claas; Fritsching, Udo

2014-03-01

In this paper the acoustic forces on particles and agglomerates caused by high-intensity ultrasound in gaseous atmosphere are derived by means of computational fluid dynamics (CFD). Sound induced forces cause an oscillating stress scenario where the primary particles of an agglomerate are alternatingly pressed together and torn apart with the frequency of the applied wave. A comparison of the calculated acoustic forces with respect to the inter particle adhesion forces from Van-der-Waals and liquid bridge interactions reveals that the separation forces may reach the same order of magnitude for 80 μm sized SiO2-particles. Hence, with finite probability acoustically agitated gases may de-agglomerate/disperse solid agglomerate structures. This effect is confirmed by dispersion experiments in an acoustic particle levitation setup. Copyright © 2013 Elsevier B.V. All rights reserved.

PENTACLE: Parallelized particle-particle particle-tree code for planet formation

Science.gov (United States)

Iwasawa, Masaki; Oshino, Shoichi; Fujii, Michiko S.; Hori, Yasunori

2017-10-01

We have newly developed a parallelized particle-particle particle-tree code for planet formation, PENTACLE, which is a parallelized hybrid N-body integrator executed on a CPU-based (super)computer. PENTACLE uses a fourth-order Hermite algorithm to calculate gravitational interactions between particles within a cut-off radius and a Barnes-Hut tree method for gravity from particles beyond. It also implements an open-source library designed for full automatic parallelization of particle simulations, FDPS (Framework for Developing Particle Simulator), to parallelize a Barnes-Hut tree algorithm for a memory-distributed supercomputer. These allow us to handle 1-10 million particles in a high-resolution N-body simulation on CPU clusters for collisional dynamics, including physical collisions in a planetesimal disc. In this paper, we show the performance and the accuracy of PENTACLE in terms of \\tilde{R}_cut and a time-step Δt. It turns out that the accuracy of a hybrid N-body simulation is controlled through Δ t / \\tilde{R}_cut and Δ t / \\tilde{R}_cut ˜ 0.1 is necessary to simulate accurately the accretion process of a planet for ≥106 yr. For all those interested in large-scale particle simulations, PENTACLE, customized for planet formation, will be freely available from https://github.com/PENTACLE-Team/PENTACLE under the MIT licence.

Glass particles produced by laser ablation for ICP-MSmeasurements

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, J.; Liu, C.; Wen, S.; Mao, X.; Russo, R.E.

2007-06-01

Pulsed laser ablation (266nm) was used to generate glass particles from two sets of standard reference materials using femtosecond (150fs) and nanosecond (4ns) laser pulses with identical fluences of 50 J cm{sup -2}. Scanning electron microscopy (SEM) images of the collected particles revealed that there are more and larger agglomerations of particles produced by nanosecond laser ablation. In contrast to the earlier findings for metal alloy samples, no correlation between the concentration of major elements and the median particle size was found. When the current data on glass were compared with the metal alloy data, there were clear differences in terms of particle size, crater depth, heat affected zone, and ICP-MS response. For example, glass particles were larger than metal alloy particles, the craters in glass were less deep than craters in metal alloys, and damage to the sample was less pronounced in glass compared to metal alloys samples. The femtosecond laser generated more intense ICP-MS signals compared to nanosecond laser ablation for both types of samples, although glass sample behavior was more similar between ns and fs-laser ablation than for metals alloys.

Aggregated particles caused by instrument artifact

Directory of Open Access Journals (Sweden)

A. M. Pierce

2018-04-01

Full Text Available Previous studies have indicated that superaggregates, clusters of aggregates of soot primary particles, can be formed in large-scale turbulent fires. Due to lower effective densities, higher porosity, and lower aerodynamic diameters, superaggregates may pass through inlets designed to remove particles  <  2.5 µm in aerodynamic diameter (PM2.5. Ambient particulate matter samples were collected at Peavine Peak, NV, USA (2515 m northwest of Reno, NV, USA from June to November 2014. The Teledyne Advanced Pollution Instrumentation (TAPI 602 BetaPlus particulate monitor was used to collect PM2.5 on two filter types. During this time, aggregated particles  >  2.5 µm in aerodynamic diameter were collected on 36 out of 158 sample days. On preliminary analysis, it was thought that these aggregated particles were superaggregates, depositing past PM10 (particles  <  10 µm in aerodynamic diameter pre-impactors and PM2.5 cyclones. However, further analysis revealed that these aggregated particles were dissimilar to superaggregates observed in previous studies, both in morphology and in elemental composition. To determine if the aggregated particles were superaggregates or an instrument artifact, samples were investigated for the presence of certain elements, the occurrence of fires, high relative humidity and wind speeds, as well as the use of generators on site. Samples with aggregated particles, referred to as aggregates, were analyzed using a scanning electron microscope for size and shape and energy dispersive X-ray spectroscopy was used for elemental analysis. It was determined, based on the high amounts of aluminum present in the aggregate samples, that a sampling artifact associated with the sample inlet and prolonged, high wind events was the probable reason for the observed aggregates.

Fractal Dimension of Particle Showers Measured in a Highly Granular Calorimeter

CERN Document Server

Ruan, Manqi; Bourdy, Vincent; Brients, Jean-Claude; Videau, Henri

2014-01-01

fractal dimension of showers measured in a high granularity calorimeter designed for a future lepton collider. The shower fractal dimension reveals detailed information of the spatial configuration of the shower. It is found to be characteristic of the type of interaction and highly sensitive to the nature of the incident particle. Using the shower fractal dimension, we demonstrate a particle identification algorithm that can efficiently separate electromagnetic showers, hadronic showers and non-showering tracks. We also find a logarithmic dependence of the shower fractal dimension on the particle energy.

Vector potential quantization and the photon wave-particle representation

International Nuclear Information System (INIS)

Meis, C; Dahoo, P R

2016-01-01

The quantization procedure of the vector potential is enhanced at a single photon state revealing the possibility for a simultaneous representation of the wave-particle nature of the photon. Its relationship to the quantum vacuum results naturally. A vector potential amplitude operator is defined showing the parallelism with the Hamiltonian of a massless particle. It is further shown that the quantized vector potential satisfies both the wave propagation equation and a linear time-dependent Schrödinger-like equation. (paper)

Reactions and mass spectra of complex particles using Aerosol CIMS

Science.gov (United States)

Hearn, John D.; Smith, Geoffrey D.

2006-12-01

Aerosol chemical ionization mass spectrometry (CIMS) is used both on- and off-line for the analysis of complex laboratory-generated and ambient particles. One of the primary advantages of Aerosol CIMS is the low degree of ion fragmentation, making this technique well suited for investigating the reactivity of complex particles. To demonstrate the usefulness of this "soft" ionization, particles generated from meat cooking were reacted with ozone and the composition was monitored as a function of reaction time. Two distinct kinetic regimes were observed with most of the oleic acid in these particles reacting quickly but with 30% appearing to be trapped in the complex mixture. Additionally, detection limits are measured to be sufficiently low (100-200 ng/m3) to detect some of the more abundant constituents in ambient particles, including sulfate, which is measured in real-time at 1.2 [mu]g/m3. To better characterize complex aerosols from a variety of sources, a novel off-line collection method was also developed in which non-volatile and semi-volatile organics are desorbed from particles and concentrated in a cold U-tube. Desorption from the U-tube followed by analysis with Aerosol CIMS revealed significant amounts of nicotine in cigarette smoke and levoglucosan in oak and pine smoke, suggesting that this may be a useful technique for monitoring particle tracer species. Additionally, secondary organic aerosol formed from the reaction of ozone with R-limonene and volatile organics from orange peel were analyzed off-line showing large molecular weight products (m/z > 300 amu) that may indicate the formation of oligomers. Finally, mass spectra of ambient aerosol collected offline reveal a complex mixture of what appears to be highly processed organics, some of which may contain nitrogen.

Particle creation by a black hole as a consequence of the Casimir effect

International Nuclear Information System (INIS)

Nugayev, R.M.

1987-01-01

Particle creation by a blackhole is investigated in terms of temperature corrections to the Casimir effect. The reduction of the Hawking effect to more familiar effects observed in the laboratory enables us to reveal the mechanism of particle creation. The blackbody nature of the Hawking radiation is due to the interaction of virtual particles with the surface of a ''cavity'' formed by the Schwarzschild gravitational field potential barrier. These particles are ''squeezed out'' by the contraction of the potential barrier and appear to an observer at J + as the real blackbody ones. (orig.)

Effect of nanosilica particles on polypropylene polymer modified asphalt mixture performance

Directory of Open Access Journals (Sweden)

Nura Bala

2018-06-01

Full Text Available The current study was conducted to investigate the effect of nanosilica particles on the performance characteristics of polymer modified asphalt binders. In this study, control 80/100 binder were modified with polypropylene polymer and nanosilica particles at concentration of 0%–4%. Both nanosilica particles and polypropylene polymer were added by weight of total bitumen content. The asphalt performance tests flexural four point beam fatigue test, indirect tensile strength, indirect tensile stiffness modulus and draindown tests are conducted to evaluate the effect of nanosilica particles. The results of the study shows that nanosilica particles improves the fatigue properties of polypropylene polymer modified binder. This indicates that nanosilica particles have significant effect on improving the performance properties of polymer modified binders. Also, the result reveals that thermoplastic polymer polypropylene with nanosilica particles when used as bitumen modifiers improve the performance and durability of asphalt mixtures. Keywords: Polypropylene, Fatigue cracking, Stiffness modulus, Modified asphalt, Draindown

Spatial confinement governs orientational order in patchy particles

Science.gov (United States)

Iwashita, Yasutaka; Kimura, Yasuyuki

2016-06-01

Orientational order in condensed matter plays a key role in determining material properties such as ferromagnetism, viscoelasticity or birefringence. We studied purely orientational ordering in closely-packed one-patch colloidal particles confined between flat substrates, where the particles can only rotate and are ordered via the sticky interaction between the patches. For the first time, we experimentally realized a rich variety of mesoscopic patterns through orientational ordering of colloids by controlling patch size and confinement thickness. The combination of experiment and numerical simulation reveals the decisive role of confinement: An ordered state(s) is selected from the (meta)stable options in bulk when it is commensurate with the system geometry and boundary conditions; otherwise, frustration induces a unique order. Our study offers a new means of systematic control over mesoscopic structures via orientational ordering in patchy particles. The system would also possess unique functionalities through the rotational response of the particles to external stimuli.

Irreversible adsorption of particles on heterogeneous surfaces.

Science.gov (United States)

Adamczyk, Zbigniew; Jaszczółt, Katarzyna; Michna, Aneta; Siwek, Barbara; Szyk-Warszyńska, Lilianna; Zembala, Maria

2005-12-30

Methods of theoretical and experimental evaluation of irreversible adsorption of particles, e.g., colloids and globular proteins at heterogeneous surfaces were reviewed. The theoretical models were based on the generalized random sequential adsorption (RSA) approach. Within the scope of these models, localized adsorption of particles occurring as a result of short-ranged attractive interactions with discrete adsorption sites was analyzed. Monte-Carlo type simulations performed according to this model enabled one to determine the initial flux, adsorption kinetics, jamming coverage and the structure of the particle monolayer as a function of the site coverage and the particle/site size ratio, denoted by lambda. It was revealed that the initial flux increased significantly with the site coverage theta(s) and the lambda parameter. This behavior was quantitatively interpreted in terms of the scaled particle theory. It also was demonstrated that particle adsorption kinetics and the jamming coverage increased significantly, at fixed site coverage, when the lambda parameter increased. Practically, for alpha = lambda2theta(s) > 1 the jamming coverage at the heterogeneous surfaces attained the value pertinent to continuous surfaces. The results obtained prove unequivocally that spherically shaped sites were more efficient in binding particles in comparison with disk-shaped sites. It also was predicted that for particle size ratio lambda charge. Particle deposition occurred under diffusion-controlled transport conditions and their coverage was evaluated by direct particle counting using the optical and electron microscopy. Adsorption kinetics was quantitatively interpreted in terms of numerical solutions of the governing diffusion equation with the non-linear boundary condition derived from Monte-Carlo simulations. It was proven that for site coverage as low as a few percent the initial flux at heterogeneous surfaces attained the maximum value pertinent to homogeneous

The long-period eccentric orbit of the particle accelerator HD 167971 revealed by long baseline interferometry

NARCIS (Netherlands)

De Becker, M.; Sana, H.; Absil, O.; Le Bouquin, J.-B.; Blomme, R.

2012-01-01

Using optical long baseline interferometry, we resolved for the first time the two wide components of HD 167971, a candidate hierarchical triple system known to efficiently accelerate particles. Our multi-epoch Very Large Telescope Interferometer observations provide direct evidence for a

Acoustically Driven Fluid and Particle Motion in Confined and Leaky Systems

Science.gov (United States)

Barnkob, Rune; Nama, Nitesh; Ren, Liqiang; Huang, Tony Jun; Costanzo, Francesco; Kähler, Christian J.

2018-01-01

The acoustic motion of fluids and particles in confined and acoustically leaky systems is receiving increasing attention for its use in medicine and biotechnology. A number of contradicting physical and numerical models currently exist, but their validity is uncertain due to the unavailability of hard-to-access experimental data for validation. We provide experimental benchmarking data by measuring 3D particle trajectories and demonstrate that the particle trajectories can be described numerically without any fitting parameter by a reduced-fluid model with leaky impedance-wall conditions. The results reveal the hitherto unknown existence of a pseudo-standing wave that drives the acoustic streaming as well as the acoustic radiation force on suspended particles.

Inorganic particle analysis of dental impression elastomers.

Science.gov (United States)

Carlo, Hugo Lemes; Fonseca, Rodrigo Borges; Soares, Carlos José; Correr, Américo Bortolazzo; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho

2010-01-01

The aim of this study was to determine quantitatively and qualitatively the inorganic particle fraction of commercially available dental elastomers. The inorganic volumetric fraction of two addition silicones (Reprosil Putty/Fluid and Flexitime Easy Putty/Fluid), three condensation silicones (Clonage Putty/Fluid, Optosil Confort/Xantopren VL and Silon APS Putty/Fluid), one polyether (Impregum Soft Light Body) and one polysulfide (Permlastic Light Body) was accessed by weighing a previously determined mass of each material in water before and after burning samples at 600 ºC, during 3 h. Unsettled material samples were soaked in acetone and chloroform for removal of the organic portion. The remaining filler particles were sputter-coated with gold evaluation of their morphology and size, under scanning electron microscopy (SEM). Flexitime Easy Putty was the material with the highest results for volumetric particle fraction, while Impregum Soft had the lowest values. Silon 2 APS Fluid presented the lowest mean filler size values, while Clonage Putty had the highest values. SEM micrographs of the inorganic particles showed several morphologies - lathe-cut, spherical, spherical-like, sticks, and sticks mixed to lathe-cut powder. The results of this study revealed differences in particle characteristics among the elastometic materials that could lead to different results when testing mechanical properties.

One century of cosmic rays – A particle physicist's view

Directory of Open Access Journals (Sweden)

Sutton Christine

2015-01-01

Full Text Available Experiments on cosmic rays and the elementary particles share a common history that dates back to the 19th century. Following the discovery of radioactivity in the 1890s, the paths of the two fields intertwined, especially during the decades after the discovery of cosmic rays. Experiments demonstrated that the primary cosmic rays are positively charged particles, while other studies of cosmic rays revealed various new sub-atomic particles, including the first antiparticle. Techniques developed in common led to the birth of neutrino astronomy in 1987 and the first observation of a cosmic γ-ray source by a ground-based cosmic-ray telescope in 1989.

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.

Assessment of particle-tracking models for dispersed particle-laden flows implemented in OpenFOAM and ANSYS FLUENT

Directory of Open Access Journals (Sweden)

Franziska Greifzu

2016-01-01

Full Text Available In the present study two benchmark problems for turbulent dispersed particle-laden flow are investigated with computational fluid dynamics (CFD. How the CFD programs OpenFOAM and ANSYS FLUENT model these flows is tested and compared. The numerical results obtained with Lagrangian–Eulerian (LE point-particle (PP models for Reynolds-averaged Navier–Stokes (RANS simulations of the fluid flow in steady state and transient modes are compared with the experimental data available in the literature. The effect of the dispersion model on the particle motion is investigated in particular, as well as the order of coupling between the continuous carrier phase and the dispersed phase. First, a backward-facing step (BFS case is validated. As a second case, the confined bluff body (CBB is used. The simulated fluid flows correspond well with the experimental data for both test cases. The results for the dispersed solid phase reveal a good accordance between the simulation results and the experiments. It seems that particle dispersion is slightly under-predicted when ANSYS FLUENT is used, whereas the applied solver in OpenFOAM overestimates the dispersion somewhat. Only minor differences between the coupling schemes are detected due to the low volume fractions and mass loadings that are investigated. In the BFS test case the importance of the spatial dimension of the numerical model is demonstrated. Even if it is reasonable to assume a two-dimensional fluid flow structure, it is crucial to simulate the turbulent particle-laden flow with a three-dimensional model since the turbulent dispersion of the particles is three-dimensional.

Many-body localization from one particle density matrix

Energy Technology Data Exchange (ETDEWEB)

Bera, Soumya; Bardarson, Jens [Max Planck Institute for the Physics of Complex Systems, Dresden (Germany); Schomerus, Henning [Lancaster University, Lancaster (United Kingdom); Heidrich-Meisner, Fabian [Ludwig-Maximilians-Universitaet Muenchen (Germany)

2016-07-01

We show that the one-particle density matrix ρ can be used to characterize the interaction-driven many-body localization transition in isolated fermionic systems. The natural orbitals (the eigenstates) are localized in the many-body localized phase and spread out when one enters the delocalized phase, while the occupation spectrum (the set of eigenvalues) reveals the distinctive Fock- space structure of the many-body eigenstates, exhibiting a step-like discontinuity in the localized phase. The associated one-particle occupation entropy is small in the localized phase and large in the delocalized phase, with diverging fluctuations at the transition.

Identity of Particles and Continuum Hypothesis

Science.gov (United States)

Berezin, Alexander A.

2001-04-01

Why all electrons are the same? Unlike other objects, particles and atoms (same isotopes) are forbidden to have individuality or personal history (or reveal their hidden variables, even if they do have them). Or at least, what we commonly call physics so far was unable to disprove particle's sameness (Berezin and Nakhmanson, Physics Essays, 1990). Consider two opposing hypotheses: (A) particles are indeed absolutely same, or (B) they do have individuality, but it is beyond our capacity to demonstrate. This dilemma sounds akin to undecidability of Continuum Hypothesis of existence (or not) of intermediate cardinalities between integers and reals (P.Cohen). Both yes and no of it are true. Thus, (alleged) sameness of electrons and atoms may be a physical translation (embodiment) of this fundamental Goedelian undecidability. Experiments unlikely to help: even if we find that all electrons are same within 30 decimal digits, could their masses (or charges) still differ in100-th digit? Within (B) personalized informationally rich (infinitely rich?) digital tails (starting at, say, 100-th decimal) may carry individual record of each particle history. Within (A) parameters (m, q) are indeed exactly same in all digits and their sameness is based on some inherent (meta)physical principle akin to Platonism or Eddington-type numerology.

Revealing low-energy part of the beta spectra

International Nuclear Information System (INIS)

Selvi, S.; Celiktas, C.

2002-01-01

An effective method is proposed to separate electronic noise from the beta-particle spectra revealing lower energy part of the spectra. The available methods for reducing the noise problem cut the noise along with the low-energy part of the beta spectra by using a discriminator. Our setup eliminates this undesirable effect by shifting the noise toward the lowest energy scale leaving the low-energy part of spectra undisturbed. We achieved this noise-pulse-separation by treating the noise as a pulse so that we can exploit the application of the pulse-shape analyzer equipment used for pulse shape identification of particles and rejection of defective pulses. To the best of our knowledge this method of the noise separation is a novel approach

Structure in nascent carbon nanotubes revealed by spatially resolved Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Landois, Périne [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Pinault, Mathieu [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Huard, Mickaël [Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Reita, Valérie [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Rouzière, Stéphan; Launois, Pascale [Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Mayne-L' Hermite, Martine [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Bendiab, Nedjma, E-mail: nedjma.bendiab@grenoble.cnrs.fr [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France)

2014-10-01

The understanding of carbon nanotube (CNT) growth is crucial for the control of their production. In particular, the identification of structural changes of carbon possibly occurring near the catalyst particle in the very early stages of their formation is of high interest. In this study, samples of nascent CNT obtained during nucleation step and samples of vertically aligned CNT obtained during growth step are analysed by combined spatially resolved Raman spectroscopy and X-ray diffraction measurements. Spatially resolved Raman spectroscopy reveals that iron-based phases and carbon phases are co-localized at the same position, and indicates that sp{sup 2} carbon nucleates preferentially on iron-based particles during this nucleation step. Depth scan Raman spectroscopy analysis, performed on nascent CNT, highlights that carbon structural organisation is significantly changing from defective graphene layers surrounding the iron-based particles at their base up to multi-walled nanotube structures in the upper part of iron-based particles. - Highlights: • Spatial co-localization of iron and carbon structures in nascent carbon nanotubes • Imaging local carbon structure changes along catalyst particles by Raman spectroscopy. • In nascent nanotubes, significant structural changes occur along catalyst particle.

Oxidation Products of Biogenic Emissions Contribute to Nucleation of Atmospheric Particles

CERN Document Server

Riccobono, Francesco; Baltensperger, Urs; Worsnop, Douglas R; Curtius, Joachim; Carslaw, Kenneth S; Wimmer, Daniela; Wex, Heike; Weingartner, Ernest; Wagner, Paul E; Vrtala, Aron; Viisanen, Yrjö; Vaattovaara, Petri; Tsagkogeorgas, Georgios; Tomé, Antonio; Stratmann, Frank; Stozhkov, Yuri; Spracklen, Dominick V; Sipilä, Mikko; Praplan, Arnaud P; Petäjä, Tuukka; Onnela, Antti; Nieminen, Tuomo; Mathot, Serge; Makhmutov, Vladimir; Lehtipalo, Katrianne; Laaksonen, Ari; Kvashin, Alexander N.; Kürten, Andreas; Kupc, Agnieszka; Keskinen, Helmi; Kajos, Maija; Junninen, Heikki; Hansel, Armin; Franchin, Alessandro; Flagan, Richard C; Ehrhart, Sebastian; Duplissy, Jonathan; Dunne, Eimear M; Downard, Andrew; David, André; Breitenlechner, Martin; Bianchi, Federico; Amorim, Antonio; Almeida, João; Rondo, Linda; Ortega, Ismael K; Dommen, Josef; Scott, Catherine E; Vrtala, Aron; Santos, Filipe D; Schallhart, Simon; Seinfeld, John H; Sipila, Mikko; Donahue, Neil M; Kirkby, Jasper; Kulmala, Markku

2014-01-01

Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations.

Synthesis of diamondlike carbon particles in/on a water substrate by laser irradiation

International Nuclear Information System (INIS)

Hidai, Hirofumi; Tokura, Hitoshi

2005-01-01

We proposed two-particle synthesis techniques using a liquid as a substrate. First, utilizing liquid instead of solid substrates, particle synthesis is expected on the liquid surface. Particles sink into the liquid before the particles grow into film, because of liquid fluidity. Second, the excitation of a gas dissolved in water was also attempted. An ArF excimer laser beam was focused in a chamber. The 60% volume of the chamber was filled with water, in which methane was dissolved and the remaining space of the chamber was filled with methane gas. As a result, diamondlike carbon particles could be synthesized in water. The particles synthesized from methane in the gas phase were 50-200 nm in diameter, and the particles synthesized from methane dissolved in water were 200-700 nm in diameter, and no structural differences were observed between the particles of two different diameters. Energy-dispersive spectroscopy, Raman spectroscopy analysis, and high-resolution transmission electron microscopy observations revealed that particles contained a diamondlike carbon component and that graphite was attached to them. These particles were harder than graphite particles

Size-sensitive particle trajectories in three-dimensional micro-bubble acoustic streaming flows

Science.gov (United States)

Volk, Andreas; Rossi, Massimiliano; Hilgenfeldt, Sascha; Rallabandi, Bhargav; Kähler, Christian; Marin, Alvaro

2015-11-01

Oscillating microbubbles generate steady streaming flows with interesting features and promising applications for microparticle manipulation. The flow around oscillating semi-cylindrical bubbles has been typically assumed to be independent of the axial coordinate. However, it has been recently revealed that particle motion is strongly three-dimensional: Small tracer particles follow vortical trajectories with pronounced axial displacements near the bubble, weaving a toroidal stream-surface. A well-known consequence of bubble streaming flows is size-dependent particle migration, which can be exploited for sorting and trapping of microparticles in microfluidic devices. In this talk, we will show how the three-dimensional toroidal topology found for small tracer particles is modified as the particle size increases up to 1/3 of the bubble radius. Our results show size-sensitive particle positioning along the axis of the semi-cylindrical bubble. In order to analyze the three-dimensional sorting and trapping capabilities of the system, experiments with an imposed flow and polydisperse particle solutions are also shown.

Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens

Science.gov (United States)

Cicek, Ahmet; Korozlu, Nurettin; Adem Kaya, Olgun; Ulug, Bulent

2017-03-01

We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.

Energetic changes caused by antigenic module insertion in a virus-like particle revealed by experiment and molecular dynamics simulations.

Directory of Open Access Journals (Sweden)

Lin Zhang

Full Text Available The success of recombinant virus-like particles (VLPs for human papillomavirus and hepatitis B demonstrates the potential of VLPs as safe and efficacious vaccines. With new modular designs emerging, the effects of antigen module insertion on the self-assembly and structural integrity of VLPs should be clarified so as to better enabling improved design. Previous work has revealed insights into the molecular energetics of a VLP subunit, capsomere, comparing energetics within various solution conditions known to drive or inhibit self-assembly. In the present study, molecular dynamics (MD simulations coupled with the molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA method were performed to examine the molecular interactions and energetics in a modular capsomere of a murine polyomavirus (MPV VLP designed to protect against influenza. Insertion of an influenza antigenic module is found to lower the binding energy within the capsomere, and a more active state is observed in Assembly Buffer as compared with that in Stabilization Buffer, which has been experimentally validated through measurements using differential scanning calorimetry. Further in-depth analysis based on free-energy decomposition indicates that destabilized binding can be attributed to electrostatic interaction induced by the chosen antigen module. These results provide molecular insights into the conformational stability of capsomeres and their abilities to be exploited for antigen presentation, and are expected to be beneficial for the biomolecular engineering of VLP vaccines.

Delocalization of Relativistic Dirac Particles in Disordered One-Dimensional Systems and Its Implementation with Cold Atoms

International Nuclear Information System (INIS)

Zhu Shiliang; Zhang Danwei; Wang, Z. D.

2009-01-01

We study theoretically the localization of relativistic particles in disordered one-dimensional chains. It is found that the relativistic particles tend to delocalization in comparison with the nonrelativistic particles with the same disorder strength. More intriguingly, we reveal that the massless Dirac particles are entirely delocalized for any energy due to the inherent chiral symmetry, leading to a well-known result that particles are always localized in one-dimensional systems for arbitrary weak disorders to break down. Furthermore, we propose a feasible scheme to detect the delocalization feature of the Dirac particles with cold atoms in a light-induced gauge field.

Particle-two particle interaction in configuration space

International Nuclear Information System (INIS)

Kuzmichev, V.E.

1982-07-01

The problem if three indentical particles with zero-range two-particle interaction is considered. An explicit expression for the effective potential between one particle and the remaining two-particle system is obtained in the coordinate representation. It is shown that for arbitrary energies, at small and, for zero energy, at large distances rho between the one particle and centre of mass of the other two particles the diagonal matrix element of the effective potential is attractive and proportional to 1/rho 2 . This property of the effective potenial explains both the Thomas singularity and the Efimov effect. In the case of zero total energy of the system the general form of the solution of the three-particle integral equation is found in configuration space. (orig.)

Shearing of particles during crack growth in polymer blends

NARCIS (Netherlands)

Pijnenburg, K.G.W.; Steenbrink, A.C.; Giessen, E.V.D.

1999-01-01

Microstructural investigations below the fracture surface have revealed that the rubber particles in a number of polymer-rubber blends were deformed into remarkable S-like shapes. These shapes seem to have been largely ignored in previous microstructural studies of blends, but in fact cannot be

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.

Particle self-assembly at ionic liquid-based interfaces.

Science.gov (United States)

Frost, Denzil S; Nofen, Elizabeth M; Dai, Lenore L

2014-04-01

This review presents an overview of the nature of ionic liquid (IL)-based interfaces and self-assembled particle morphologies of IL-in-water, oil- and water-in-IL, and novel IL-in-IL Pickering emulsions with emphasis on their unique phenomena, by means of experimental and computational studies. In IL-in-water Pickering emulsions, particles formed monolayers at ionic liquid-water interfaces and were close-packed on fully covered emulsion droplets or aggregated on partially covered droplets. Interestingly, other than equilibrating at the ionic liquid-water interfaces, microparticles with certain surface chemistries were extracted into the ionic liquid phase with a high efficiency. These experimental findings were supported by potential of mean force calculations, which showed large energy drops as hydrophobic particles crossed the interface into the IL phase. In the oil- and water-in-IL Pickering emulsions, microparticles with acidic surface chemistries formed monolayer bridges between the internal phase droplets rather than residing at the oil/water-ionic liquid interfaces, a significant deviation from traditional Pickering emulsion morphology. Molecular dynamics simulations revealed aspects of the mechanism behind this bridging phenomenon, including the role of the droplet phase, surface chemistry, and inter-particle film. Novel IL-in-IL Pickering emulsions exhibited an array of self-assembled morphologies including the previously observed particle absorption and bridging phenomena. The appearance of these morphologies depended on the particle surface chemistry as well as the ILs used. The incorporation of particle self-assembly with ionic liquid science allows for new applications at the intersection of these two fields, and have the potential to be numerous due to the tunability of the ionic liquids and particles incorporated, as well as the particle morphology by combining certain groups of particle surface chemistry, IL type (protic or aprotic), and whether oil

Superparamagnetism in carbon-coated Co particles produced by the Kratschmer carbon arc process

Science.gov (United States)

McHenry, M. E.; Majetich, S. A.; Artman, J. O.; Degraef, M.; Staley, S. W.

1994-04-01

A process based on the Kratschmer-Huffman carbon arc method of preparing fullerenes has been used to generate carbon-coated cobalt and cobalt carbide nanocrystallites. Magnetic nanocrystallites are extracted from the soot with a gradient field technique. For Co/C composites, structural characterization by x-ray diffraction and high-resolution transmission electron microscopy reveals the presence of a fcc Co phase, graphite, and a minority Co2C phase. The majority of Co nanocrystals exists as nominally spherical particles, 0.5-5 nm in radius. Hysteretic and temperature-dependent magnetic response, in randomly and magnetically aligned powder samples frozen in epoxy reveals fine-particle magnetism associated with monodomain Co particles. The magnetization exhibits a unique functional dependence on H/T, and hysteresis below a blocking temperature, TB~=160 K. Below TB, the temperature dependence of the coercivity is given by Hc=Hci[1-(T/TB)1/2], with Hci~=450 Oe.

Fermilab | Science | Particle Physics | Benefits of Particle Physics

Science.gov (United States)

Photos and videos Latest news For the media Particle Physics Neutrinos Fermilab and the LHC Dark matter initiatives Research and development Key discoveries Benefits of particle physics Particle Accelerators society Particle Physics 101 Science of matter, energy, space and time How particle physics discovery

Synthesis of Uncarbonised Coconut Shell Nanoparticles: Characterisation and Particle Size Determination

Directory of Open Access Journals (Sweden)

S.A. Bello

2015-06-01

Full Text Available The possibility of using mechanical milling for the synthesis of uncarbonised coconut shell nanoparticles (UCSNPs has been investigated. UCSNPs were synthesized from discarded coconut shells (CSs using top down approach. The sundried CSs were crushed, ground and then sieved using hammer crusher, a two disc grinder and set of sieves with shine shaker respectively. The CS powders retained in the pan below 37 µm sized sieve were milled for 70 hours to obtain UCSNPS. Samples for analysis were taken at 16 and 70 hours. UCSNPs were analyzed using transmission electron microscope (TEM, scanning electron microscope (SEM with attached EDS and Gwyddion software. Samples of UCSNPs obtained at 16 and 70hours show that the deep brown colour of the initial CS powder became fading as the milling hour increased. The size determination from TEM image revealed spherical particles with an average size of 18.23 nm for UCSNPs obtained at 70 hour milling. The EDS spectrographs revealed an increase in the carbon counts with increased milling hours. This is attributable to dryness of the CS powders by the heat generated during the milling process due to absorption of kinetic energy by the CS powders from the milling balls. SEM micrographs revealed UCSNPs in agglomerated networks. The SEM micrograph/Gyweddion particles size determination showed average particles of 170.5 ±3 and 104.9 ±4.1 nm for UCSNPs obtained at 16 and 70 hours respectively. Therefore, production of UCSNPs through mechanical milling using mixture of ceramic balls of different sizes has been established especially when the particles of the sourced/initial CS powders falls below 37 µm.

Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method.

Science.gov (United States)

Kalani, Mahshid; Yunus, Robiah

2012-01-01

The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks.

Inhibition of surface crystallisation of amorphous indomethacin particles in physical drug-polymer mixtures

DEFF Research Database (Denmark)

Priemel, Petra A; Laitinen, Riikka; Barthold, Sarah

2013-01-01

stability than pure IMC whereas IMC Soluplus(®) mixtures did not. Water uptake was higher for mixtures containing Soluplus(®) than for amorphous IMC or IMC Eudragit(®) mixtures. However, the Tg of amorphous IMC was unaffected by the presence (and nature) of polymer. SEM revealed that Eudragit(®) particles...... through reduced IMC surface molecular mobility. Polymer particles may also mechanically hinder crystal growth outwards from the surface. This work highlights the importance of microparticulate surface coverage of amorphous drug particles on their stability....

Hubble Images Reveal Jupiter's Auroras

Science.gov (United States)

1996-01-01

These images, taken by the Hubble Space Telescope, reveal changes in Jupiter's auroral emissions and how small auroral spots just outside the emission rings are linked to the planet's volcanic moon, Io. The images represent the most sensitive and sharply-detailed views ever taken of Jovian auroras.The top panel pinpoints the effects of emissions from Io, which is about the size of Earth's moon. The black-and-white image on the left, taken in visible light, shows how Io and Jupiter are linked by an invisible electrical current of charged particles called a 'flux tube.' The particles - ejected from Io (the bright spot on Jupiter's right) by volcanic eruptions - flow along Jupiter's magnetic field lines, which thread through Io, to the planet's north and south magnetic poles. This image also shows the belts of clouds surrounding Jupiter as well as the Great Red Spot.The black-and-white image on the right, taken in ultraviolet light about 15 minutes later, shows Jupiter's auroral emissions at the north and south poles. Just outside these emissions are the auroral spots. Called 'footprints,' the spots are created when the particles in Io's 'flux tube' reach Jupiter's upper atmosphere and interact with hydrogen gas, making it fluoresce. In this image, Io is not observable because it is faint in the ultraviolet.The two ultraviolet images at the bottom of the picture show how the auroral emissions change in brightness and structure as Jupiter rotates. These false-color images also reveal how the magnetic field is offset from Jupiter's spin axis by 10 to 15 degrees. In the right image, the north auroral emission is rising over the left limb; the south auroral oval is beginning to set. The image on the left, obtained on a different date, shows a full view of the north aurora, with a strong emission inside the main auroral oval.The images were taken by the telescope's Wide Field and Planetary Camera 2 between May 1994 and September 1995.This image and other images and data

The mixing of particle clouds plunging into water

Energy Technology Data Exchange (ETDEWEB)

Angelini, S.; Theofanous, T.G.; Yuen, W.W. [Univ. of California, Santa Barbara, CA (United States)

1995-09-01

This work addresses certain fundamental aspects of the premixing phase of steam explosions, At issue are the multifield interaction aspects under highly transient, multidimensional conditions, and in presence of strong phase changes. They are addressed in an experiment (the MAGICO-2000) involving well-characterized particle clouds mixing with water, and detailed measurements on both external and internal characteristics of the mixing zone. Both cold and hot (up to 1500{degrees}C) particle clouds are considered in conjunction with saturated and subcooled water pools. The PMALPHA code is used as an aid in interpreting the experimental results, and the exercise reveals good predictive capabilities for it.

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).

Feature of Dust Particles in the Spring Free Troposphere over Dunhuang in Northwestern China: Electron Microscopic Experiments on Individual Particles Collected with a Balloon-borne Impactor

International Nuclear Information System (INIS)

Yamada, M.; Iwasaka, Y.; Matsuki, A.; Trochkine, D.; Kim, Y. S.; Zhang, D.; Nagatani, T.; Shi, G.-Y.; Nagatani, M.; Nakata, H.; Shen, Z.; Chen, B.; Li, G.

2005-01-01

Free tropospheric aerosol particles were collected using a balloon-borne particle impactor in August of 2002 and March of 2003 at Dunhuang in northwestern China (40 o 00'N, 94 o 30'E), and the morphology and elemental composition of the aerosol particles were analyzed in order to understand the mixing state of coarse dust particles (diameter >1 μm) over the desert areas in the Asian continent in spring. Electron microscopic experiments on the particles revealed that dust particles were major constituents of coarse mode particles in the free troposphere over the Taklamakan Desert in spring and summer.Si-rich or Ca-rich particles are major components of dust particles collected in the free troposphere over dunhuang and the values of [number of Ca-rich particles]/[number of Si-rich particles] differs markedly between spring and summer, being about 0.3 in the spring of 2003 and about 1.0 in the summer of 2002 at heights 3-5 km above sea level. It is likely that the condition of the ground surface and the strength of vertical mixing in source areas of Asian dust are potential factors causing the difference in the chemical types of dust particles.Comparison of the elemental compositions of these particles with those of particles collected over Japan strongly suggests that these particles were chemically modified during their long-range transport in the free troposphere. Analysis of wind systems shows that both the predominating westerly wind in the free troposphere and the surface wind strongly controlled by the geographical structure of the Tarim Basin are important in the long-range transport of KOSA particles originating in the Taklamakan Desert

Characterization of typical metal particles during haze episodes in Shanghai, China.

Science.gov (United States)

Li, Rui; Yang, Xin; Fu, Hongbo; Hu, Qingqing; Zhang, Liwu; Chen, Jianmin

2017-08-01

Aerosol particles were collected during three heavy haze episodes at Shanghai in the winter of 2013. Transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy was used to study the morphology and speciation of typical metal particles at a single-particle level. In addition, time-of-flight aerosol mass spectrometry (ATOFMS) was applied to identify the speciation of the Fe-containing particles. TEM analysis indicated that various metal-containing particles were hosted by sulfates, nitrates, and oxides. Fe-bearing particles mainly originated from vehicle emissions and/or steel production. Pb-, Zn-, and Sb-bearing particles were mainly contributed by anthropogenic sources. Fe-bearing particles were clustered into six groups by ATOFMS: Fe-Carbon, Fe-Inorganic, Fe-Trace metal, Fe-CN, Fe-PO 3, and Fe-NO 3 . ATOFMS data suggested that Fe-containing particles corresponded to different origins, including industrial activities, resuspension of dusts, and vehicle emissions. Fe-Carbon and Fe-CN particles displayed significant diurnal variation, and high levels were observed during the morning rush hours. Fe-Inorganic and Fe-Trace metal particle levels peaked at night. Furthermore, Fe-Carbon and Fe-PO 3 were mainly concentrated in the fine particles. Fe-CN, Fe-Inorganic, and Fe-Trace metal exhibited bimodal distribution. The mixing state of the particles revealed that all Fe-bearing particles tended to be mixed with sulfate and nitrate. The data presented herein is essential for elucidating the origin, evolution processes, and health effects of metal-bearing particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dispersion of Sound in Dilute Suspensions with Nonlinear Particle Relaxation

Science.gov (United States)

Kandula, Max

2010-01-01

The theory accounting for nonlinear particle relaxation (viscous and thermal) has been applied to the prediction of dispersion of sound in dilute suspensions. The results suggest that significant deviations exist for sound dispersion between the linear and nonlinear theories at large values of Omega(Tau)(sub d), where Omega is the circular frequency, and Tau(sub d) is the Stokesian particle relaxation time. It is revealed that the nonlinear effect on the dispersion coefficient due to viscous contribution is larger relative to that of thermal conduction

Preparation and Characterization of Pyrotechnics Binder-Coated Nano-Aluminum Composite Particles

Science.gov (United States)

Ye, Mingquan; Zhang, Shuting; Liu, Songsong; Han, Aijun; Chen, Xin

2017-07-01

The aim of this article is to protect the activity of nano-aluminum (Al) particles in solid rocket propellants and pyrotechnics. The morphology, structure, active aluminum content, and thermal and catalytic properties of the coated samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry-differential scanning calorimetry (TG-DSC), and oxidation-reduction titration methods. The results indicated that nano-Al particles could be effectively coated with phenolic resin (PF), fluororubber (Viton B), and shellac through a solvent/nonsolvent method. The energetic composite particles have core-shell structures and the thickness of the coating film is about 5-15 nm. Analysis of the active Al content revealed that Viton B coating had a much better protective effect. The TG-DSC results showed that the energy amount and energy release rate of PF-, Viton B-, and shellac-coated Al particles were larger than those of the raw nano-Al particles. The catalytic effects of coated Al particles on the thermal decomposition of ammonium perchlorate (AP) were better than those of raw nano-Al particles, and the effect of shellac-coated Al particles was significantly better than that of Viton B-coated Al particles.

Oxidation products of biogenic emissions contribute to nucleation of atmospheric particles.

Science.gov (United States)

Riccobono, Francesco; Schobesberger, Siegfried; Scott, Catherine E; Dommen, Josef; Ortega, Ismael K; Rondo, Linda; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; David, André; Downard, Andrew; Dunne, Eimear M; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Hansel, Armin; Junninen, Heikki; Kajos, Maija; Keskinen, Helmi; Kupc, Agnieszka; Kürten, Andreas; Kvashin, Alexander N; Laaksonen, Ari; Lehtipalo, Katrianne; Makhmutov, Vladimir; Mathot, Serge; Nieminen, Tuomo; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud P; Santos, Filipe D; Schallhart, Simon; Seinfeld, John H; Sipilä, Mikko; Spracklen, Dominick V; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Tsagkogeorgas, Georgios; Vaattovaara, Petri; Viisanen, Yrjö; Vrtala, Aron; Wagner, Paul E; Weingartner, Ernest; Wex, Heike; Wimmer, Daniela; Carslaw, Kenneth S; Curtius, Joachim; Donahue, Neil M; Kirkby, Jasper; Kulmala, Markku; Worsnop, Douglas R; Baltensperger, Urs

2014-05-16

Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations. Copyright © 2014, American Association for the Advancement of Science.

Effect of dispersed phase particle size on microstructure of cup fracture

International Nuclear Information System (INIS)

Goritskij, V.M.; Guseva, I.A.

1978-01-01

A correlation-regressive analysis has been carried out to reveal the influence of the size and the mean distance between the disperse particles of deposits V(C,N) on the microstructure (size of micropores and cups, density of the cups) of a viscous cup-like fracture of specimens made of 30Kh2NMFA grade steel that has been hardened and annealed. It is shown that micropores develop at relatively large particles of deposits V(C,N) (>=0.04/m). A strong correlation linear connection exists between the size of a disperse particle of deposits V(C,N), the size of micropore and cup. This connection is attributable to the close, pairwise correlative connection between the size of the particle and the micropore, the micropore and the cup

Spacer geometry and particle deposition in spiral wound membrane feed channels

KAUST Repository

Radu, A.I.

2014-11-01

Deposition of microspheres mimicking bacterial cells was studied experimentally and with a numerical model in feed spacer membrane channels, as used in spiral wound nanofiltration (NF) and reverse osmosis (RO) membrane systems. In-situ microscopic observations in membrane fouling simulators revealed formation of specific particle deposition patterns for different diamond and ladder feed spacer orientations. A three-dimensional numerical model combining fluid flow with a Lagrangian approach for particle trajectory calculations could describe very well the in-situ observations on particle deposition in flow cells. Feed spacer geometry, positioning and cross-flow velocity sensitively influenced the particle transport and deposition patterns. The deposition patterns were not influenced by permeate production. This combined experimental-modeling approach could be used for feed spacer geometry optimization studies for reduced (bio)fouling. © 2014 Elsevier Ltd.

Revealing Tripartite Quantum Discord with Tripartite Information Diagram

Directory of Open Access Journals (Sweden)

Wei-Ting Lee

2017-11-01

Full Text Available A new measure based on the tripartite information diagram is proposed for identifying quantum discord in tripartite systems. The proposed measure generalizes the mutual information underlying discord from bipartite to tripartite systems, and utilizes both one-particle and two-particle projective measurements to reveal the characteristics of the tripartite quantum discord. The feasibility of the proposed measure is demonstrated by evaluating the tripartite quantum discord for systems with states close to Greenberger–Horne–Zeilinger, W, and biseparable states. In addition, the connections between tripartite quantum discord and two other quantum correlations—namely genuine tripartite entanglement and genuine tripartite Einstein–Podolsky–Rosen steering—are briefly discussed. The present study considers the case of quantum discord in tripartite systems. However, the proposed framework can be readily extended to general N-partite systems.

Self-Propagating Reactive Fronts in Compacts of Multilayered Particles

International Nuclear Information System (INIS)

Sraj, I.; Vohra, M.; Alawieh, L.; Weihs, T.P.; Knio, O.M.

2013-01-01

Reactive multilayered foils in the form of thin films have gained interest in various applications such as joining, welding, and ignition. Typically, thin film multilayers support self-propagating reaction fronts with speeds ranging from 1 to 20 m/s. In some applications, however, reaction fronts with much smaller velocities are required. This recently motivated Fritz et al. (2011) to fabricate compacts of regular sized/shaped multilayered particles and demonstrate self-sustained reaction fronts having much smaller velocities than thin films with similar layering. In this work, we develop a simplified numerical model to simulate the self-propagation of reactive fronts in an idealized compact, comprising identical Ni/Al multilayered particles in thermal contact. The evolution of the reaction in the compact is simulated using a two-dimensional transient model, based on a reduced description of mixing, heat release, and thermal transport. Computed results reveal that an advancing reaction front can be substantially delayed as it crosses from one particle to a neighboring particle, which results in a reduced mean propagation velocity. A quantitative analysis is thus conducted on the dependence of these phenomena on the contact area between the particles, the thermal contact resistance, and the arrangement of the multilayered particles.

Self-Propagating Reactive Fronts in Compacts of Multilayered Particles

Directory of Open Access Journals (Sweden)

Ihab Sraj

2013-01-01

Full Text Available Reactive multilayered foils in the form of thin films have gained interest in various applications such as joining, welding, and ignition. Typically, thin film multilayers support self-propagating reaction fronts with speeds ranging from 1 to 20 m/s. In some applications, however, reaction fronts with much smaller velocities are required. This recently motivated Fritz et al. (2011 to fabricate compacts of regular sized/shaped multilayered particles and demonstrate self-sustained reaction fronts having much smaller velocities than thin films with similar layering. In this work, we develop a simplified numerical model to simulate the self-propagation of reactive fronts in an idealized compact, comprising identical Ni/Al multilayered particles in thermal contact. The evolution of the reaction in the compact is simulated using a two-dimensional transient model, based on a reduced description of mixing, heat release, and thermal transport. Computed results reveal that an advancing reaction front can be substantially delayed as it crosses from one particle to a neighboring particle, which results in a reduced mean propagation velocity. A quantitative analysis is thus conducted on the dependence of these phenomena on the contact area between the particles, the thermal contact resistance, and the arrangement of the multilayered particles.

Micro- and Nanostructural Characteristics of Particles Before and After an Exhaust Gas Recirculation System Scrubber

DEFF Research Database (Denmark)

Lieke, Kirsten Inga; Rosenørn, Thomas; Pedersen, Jannik

2013-01-01

microscopy (TEM) grids on two stages. Micro- and nanostructural characteristics of sin-gle particles were studied by TEM. Image analysis was carried out on overview and high-resolution images, revealing influence of the exhaust gas treatment (scrubber) on the particle morphology and mixing state. Soot......This work provides insight into the morphology and mixing state of submicron particles in diesel exhaust from a ship engine with an exhaust gas recirculation scrubber. Particles from this low-speed ship engine on test bed were collected using a microiner-tial impactor with transmission electron...

Investigation of energetic particle induced geodesic acoustic mode

Science.gov (United States)

Schneller, Mirjam; Fu, Guoyong; Chavdarovski, Ilija; Wang, Weixing; Lauber, Philipp; Lu, Zhixin

2017-10-01

Energetic particles are ubiquitous in present and future tokamaks due to heating systems and fusion reactions. Anisotropy in the distribution function of the energetic particle population is able to excite oscillations from the continuous spectrum of geodesic acoustic modes (GAMs), which cannot be driven by plasma pressure gradients due to their toroidally and nearly poloidally symmetric structures. These oscillations are known as energetic particle-induced geodesic acoustic modes (EGAMs) [G.Y. Fu'08] and have been observed in recent experiments [R. Nazikian'08]. EGAMs are particularly attractive in the framework of turbulence regulation, since they lead to an oscillatory radial electric shear which can potentially saturate the turbulence. For the presented work, the nonlinear gyrokinetic, electrostatic, particle-in-cell code GTS [W.X. Wang'06] has been extended to include an energetic particle population following either bump-on-tail Maxwellian or slowing-down [Stix'76] distribution function. With this new tool, we study growth rate, frequency and mode structure of the EGAM in an ASDEX Upgrade-like scenario. A detailed understanding of EGAM excitation reveals essential for future studies of EGAM interaction with micro-turbulence. Funded by the Max Planck Princeton Research Center. Computational resources of MPCDF and NERSC are greatefully acknowledged.

Modeling the C. elegans nematode and its environment using a particle system.

Science.gov (United States)

Rönkkö, Mauno; Wong, Garry

2008-07-21

A particle system, as understood in computer science, is a novel technique for modeling living organisms in their environment. Such particle systems have traditionally been used for modeling the complex dynamics of fluids and gases. In the present study, a particle system was devised to model the movement and feeding behavior of the nematode Caenorhabditis elegans in three different virtual environments: gel, liquid, and soil. The results demonstrate that distinct movements of the nematode can be attributed to its mechanical interactions with the virtual environment. These results also revealed emergent properties associated with modeling organisms within environment-based systems.

Particle Pollution

Science.gov (United States)

... Your Health Particle Pollution Public Health Issues Particle Pollution Recommend on Facebook Tweet Share Compartir Particle pollution — ... see them in the air. Where does particle pollution come from? Particle pollution can come from two ...

Full particle simulations of quasi-perpendicular shocks

Science.gov (United States)

Lembège, B.

This tutorial-style review is dedicated to the different strategies and constraints used for analysing the dynamics of a collisionless shocks with full particle simulations. Main results obtained with such simulations can be found in published materials (recent references are provided in this text); these will be only quoted herein in order to illustrate a few aspects of these simulations. Thanks to the large improvement of super computers, full particle simulations reveal to be quite helpful for analyzing in details the dynamics of collisionless shocks. The main characteristics of such codes can be shortly reminded as follows: one resolves the full set of Poisson and Maxwell's equations without any approximation. Two approaches are commonly used for resolving this equation's set, more precisely the space derivatives: (i) the finite difference approach and (ii) the use of FFT's (Fast Fourier Transform). Two advantages of approach (ii) are that FFT's are highly optimized in supercomputers libraries, and these allow to separate all fields components into two groups: the longitudinal electrostatic component El (solution of Poisson equation) and the transverse electromagnetic components Et and Bt solutions of the Maxwell's equations (so called "fields pusher"). Such a separation is quite helpful in the post processing stage necessary for the data analysis, as will be explained in the presentation. both ions and electrons populations are treated as individual finite-size particles and suffer the effects of all fields via the Lorentz force, so called "particle pusher", which is applied to each particle. Because of the large number of particles commonly used, the particle pusher represents the most expensive part of the calculations on which most efforts of optimisation needs to be performed (in terms of "vectorisation" or of "parallelism"). Relativistic effects may be included in this force via the use of particle momemtum. Each particle has three velocity components (vx

Haemocompatibility Of Non-Functionalized And Plasmachemical Functionalized Detonation Nanodiamond Particles

Directory of Open Access Journals (Sweden)

Mitura K.

2015-09-01

Full Text Available The purpose of this paper is to present the innovative design of microwave plasma system for modification of detonation nanodiamond particles (DNP using a special rotating drum placed inside the reactor. Nanodiamond particles manufactured by detonation method reveal the biological activity depending on surface functionalization. Plasmachemical modification of detonation nanodiamond particles gives the possibility of controlling surface of nanodiamonds particles in biological tests. In this paper we would like to compare detonation nanodiamond (the grain sizes from 2 to 5 nm with modified detonation nanodiamond in rotary reactor chamber, by microwave plasma activated chemical vapour deposition (MW PACVD method in materials research (Raman and FT-IR spectroscopy and in vitro examinations with full of human blood. The results indicate haemocompatibility of non-modified detonation nanodiamond and modified nanodiamond by MW PACVD method in rotary reactor chamber (modified ND-3 and the presence of haemolysis in commercial detonation nanodiamond.

The number of elementary particles in a fractal M-theory of 11.2360667977 dimensions

International Nuclear Information System (INIS)

He, J.-H.

2007-01-01

It is generally accepted that there are 60 experimentally found particles. The standard model strongly predicts two more hypothetical particles, the Higgs and the graviton. This paper reveals other possible scenario for predicting 69 particles at different energy scales in 11+φ 3 fractal dimensions of a fractal M theory, where φ=(5-1)/2. A modified Newton's law is suggested to experimentally verify our predictions at extremely small quantum scales. The modified Newton's law is in harmony with Heisenberg's uncertainty principle

Chlorine disinfection of grey water for reuse: effect of organics and particles.

Science.gov (United States)

Winward, Gideon P; Avery, Lisa M; Stephenson, Tom; Jefferson, Bruce

2008-01-01

Adequate disinfection of grey water prior to reuse is important to prevent the potential transmission of disease-causing microorganisms. Chlorine is a widely utilised disinfectant and as such is a leading contender for disinfection of grey water intended for reuse. This study examined the impact of organics and particles on chlorine disinfection of grey water, measured by total coliform inactivation. The efficacy of disinfection was most closely linked with particle size. Larger particles shielded total coliforms from inactivation and disinfection efficacy decreased with increasing particle size. Blending to extract particle-associated coliforms (PACs) following chlorine disinfection revealed that up to 91% of total coliforms in chlorinated grey water were particle associated. The organic concentration of grey water affected chlorine demand but did not influence the disinfection resistance of total coliforms when a free chlorine residual was maintained. Implications for urban water reuse are discussed and it is recommended that grey water treatment systems target suspended solids removal to ensure removal of PACs prior to disinfection.

Relativistic particles with spin and antisymmetric tensor fields

International Nuclear Information System (INIS)

Sandoval Junior, L.

1990-09-01

A study is made on antisymmetric tensor fields particularly on second order tensor field as far as his equivalence to other fields and quantization through the path integral are concerned. Also, a particle model is studied which has been recently proposed and reveals to be equivalent to antisymmetric tensor fields of any order. (L.C.J.A.)

Single-Molecule Fluorescence Microscopy Reveals Local Diffusion Coefficients in the Pore Network of an Individual Catalyst Particle

NARCIS (Netherlands)

Hendriks, Frank|info:eu-repo/dai/nl/412642697; Meirer, Florian; Kubarev, Alexey V.; Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Roeffaers, Maarten B J; Vogt, Eelco T. C.|info:eu-repo/dai/nl/073717398; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

2017-01-01

We used single-molecule fluorescence microscopy to study self-diffusion of a feedstock-like probe molecule with nanometer accuracy in the macropores of a micrometer-sized, real-life fluid catalytic cracking (FCC) particle. Movies of single fluorescent molecules allowed their movement through the

Electrodeposition, characterization, and antibacterial activity of zinc/silver particle composite coatings

Energy Technology Data Exchange (ETDEWEB)

Reyes-Vidal, Y.; Suarez-Rojas, R.; Ruiz, C.; Torres, J. [Center of Research and Technological Development in Electrochemistry (CIDETEQ), Parque Tecnológico Sanfandila, Pedro Escobedo, Querétaro, A.P.064, C.P.76703, Querétaro (Mexico); Ţălu, Ştefan [Technical University of Cluj-Napoca, Faculty of Mechanical Engineering, Department of AET, Discipline of Descriptive Geometry and Engineering Graphics, 103-105 B-dul Muncii St., Cluj-Napoca 400641 Cluj (Romania); Méndez, Alia [Centro de Química-ICUAP Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria Puebla, 72530 Puebla (Mexico); Trejo, G., E-mail: gtrejo@cideteq.mx [Center of Research and Technological Development in Electrochemistry (CIDETEQ), Parque Tecnológico Sanfandila, Pedro Escobedo, Querétaro, A.P.064, C.P.76703, Querétaro (Mexico)

2015-07-01

Highlights: • Zn/AgPs composites coatings were formed for electrodeposition. • CTAB promotes occlusion of silver particles in the coating. • Zn/AgPs coatings present very good antibacterial activity. - Abstract: Composite coatings consisting of zinc and silver particles (Zn/AgPs) with antibacterial activity were prepared using an electrodeposition technique. The morphology, composition, and structure of the Zn/AgPs composite coatings were analyzed using scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), inductively coupled plasma (ICP) spectrometry, and X-ray diffraction (XRD). The antibacterial properties of the coatings against the microorganisms Escherichia coli as a model Gram-negative bacterium and Staphylococcus aureus as a model Gram-positive bacterium were studied quantitatively and qualitatively. The results revealed that the dispersant cetyltrimethylammonium bromide (CTAB) assisted in the formation of a stable suspension of Ag particles in the electrolytic bath for 24 h. Likewise, a high concentration of CTAB in the electrolytic bath promoted an increase in the number of Ag particles occluded in the Zn/AgPs coatings. The Zn/AgPs coatings that were obtained were compact, smooth, and shiny materials. Antimicrobial tests performed on the Zn/AgPs coatings revealed that the inhibition of bacterial growth after 30 min of contact time was between 91% and 98% when the AgPs content ranged from 4.3 to 14.0 mg cm{sup −3}.

Coupling fine particle and bedload transport in gravel-bedded streams

Science.gov (United States)

Park, Jungsu; Hunt, James R.

2017-09-01

Fine particles in the silt- and clay-size range are important determinants of surface water quality. Since fine particle loading rates are not unique functions of stream discharge this limits the utility of the available models for water quality assessment. Data from 38 minimally developed watersheds within the United States Geological Survey stream gauging network in California, USA reveal three lines of evidence that fine particle release is coupled with bedload transport. First, there is a transition in fine particle loading rate as a function of discharge for gravel-bedded sediments that does not appear when the sediment bed is composed of sand, cobbles, boulders, or bedrock. Second, the discharge at the transition in the loading rate is correlated with the initiation of gravel mobilization. Third, high frequency particle concentration and discharge data are dominated by clockwise hysteresis where rising limb discharges generally have higher concentrations than falling limb discharges. These three observations across multiple watersheds lead to a conceptual model that fine particles accumulate within the sediment bed at discharges less than the transition and then the gravel bed fluidizes with fine particle release at discharges above the transition discharge. While these observations were individually recognized in the literature, this analysis provides a consistent conceptual model based on the coupling of fine particle dynamics with filtration at low discharges and gravel bed fluidization at higher discharges.

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.

Effective particle magnetic moment of multi-core particles

Energy Technology Data Exchange (ETDEWEB)

Ahrentorp, Fredrik; Astalan, Andrea; Blomgren, Jakob; Jonasson, Christian [Acreo Swedish ICT AB, Arvid Hedvalls backe 4, SE-411 33 Göteborg (Sweden); Wetterskog, Erik; Svedlindh, Peter [Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Lak, Aidin; Ludwig, Frank [Institute of Electrical Measurement and Fundamental Electrical Engineering, TU Braunschweig, D‐38106 Braunschweig Germany (Germany); IJzendoorn, Leo J. van [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Westphal, Fritz; Grüttner, Cordula [Micromod Partikeltechnologie GmbH, D ‐18119 Rostock (Germany); Gehrke, Nicole [nanoPET Pharma GmbH, D ‐10115 Berlin Germany (Germany); Gustafsson, Stefan; Olsson, Eva [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Johansson, Christer, E-mail: christer.johansson@acreo.se [Acreo Swedish ICT AB, Arvid Hedvalls backe 4, SE-411 33 Göteborg (Sweden)

2015-04-15

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

Effective particle magnetic moment of multi-core particles

International Nuclear Information System (INIS)

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

2015-01-01

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

Effective particle magnetic moment of multi-core particles

Science.gov (United States)

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

2015-04-01

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

Investigation of the evolution of atmospheric particles with integration of the stochastic particle-resolved model partmc-mosaic and atmospheric measurements

Science.gov (United States)

Tian, Jian

With the recently-developed particle-resolved model PartMC-MOSAIC, the mixing state and other physico-chemical properties of individual aerosol particles can be tracked as the particles undergo aerosol aging processes. However, existing PartMC-MOSAIC applications have mainly been based on idealized scenarios, and a link to real atmospheric measurement has not yet been established. In this thesis, we extend the capability of PartMC-MOSAIC and apply the model framework to three distinct scenarios with different environmental conditions to investigate the physical and chemical aging of aerosols in those environments. The first study is to investigate the evolution of particle mixing state and cloud condensation nuclei (CCN) activation properties in a ship plume. Comparisons of our results with observations from the QUANTIFY Study in 2007 in the English channel and the Gulf of Biscay showed that the model was able to reproduce the observed evolution of total number concentration and the vanishing of the nucleation mode consisting of sulfate particles. Further process analysis revealed that during the first hour after emission, dilution reduced the total number concentration by four orders of magnitude, while coagulation reduced it by an additional order of magnitude. Neglecting coagulation resulted in an overprediction of more than one order of magnitude in the number concentration of particles smaller than 40 nm at a plume age of 100 s. Coagulation also significantly altered the mixing state of the particles, leading to a continuum of internal mixtures of sulfate and black carbon. The impact of condensation on CCN concentrations depended on the supersaturation threshold at which CCN activity was evaluated. Nucleation was observed to have a limited impact on the CCN concentration in the ship plume we studied, but was sensitive to formation rates of secondary aerosol. For the second study we adapted PartMC to represent the aerosol evolution in an aerosol chamber, with

Four-particle scattering with three-particle interactions

International Nuclear Information System (INIS)

Adhikari, S.K.

1979-01-01

The four-particle scattering formalism proposed independently by Alessandrini, by Mitra et al., by Rosenberg, and by Takahashi and Mishima is extended to include a possible three-particle interaction. The kernel of the new equations we get contain both two- and three-body connected parts and gets four-body connected after one iteration. On the other hand, the kernel of the original equations in the absence of three-particle interactions does not have a two-body connected part. We also write scattering equations for the transition operators connecting the two-body fragmentation channels. They are generalization of the Sloan equations in the presence of three-particle interactions. We indicate how to include approximately the effect of a weak three-particle interaction in a practical four-particle scattering calculation

Metabolomics reveals impaired maturation of HDL particles in adolescents with hyperinsulinaemic androgen excess.

Science.gov (United States)

Samino, Sara; Vinaixa, Maria; Díaz, Marta; Beltran, Antoni; Rodríguez, Miguel A; Mallol, Roger; Heras, Mercedes; Cabre, Anna; Garcia, Lorena; Canela, Nuria; de Zegher, Francis; Correig, Xavier; Ibáñez, Lourdes; Yanes, Oscar

2015-06-23

Hyperinsulinaemic androgen excess (HIAE) in prepubertal and pubertal girls usually precedes a broader pathological phenotype in adulthood that is associated with anovulatory infertility, metabolic syndrome and type 2 diabetes. The metabolic derangements that determine these long-term health risks remain to be clarified. Here we use NMR and MS-based metabolomics to show that serum levels of methionine sulfoxide in HIAE girls are an indicator of the degree of oxidation of methionine-148 residue in apolipoprotein-A1. Oxidation of apo-A1 in methionine-148, in turn, leads to an impaired maturation of high-density lipoproteins (HDL) that is reflected in a decline of large HDL particles. Notably, such metabolic alterations occur in the absence of impaired glucose tolerance, hyperglycemia and hypertriglyceridemia, and were partially restored after 18 months of treatment with a low-dose combination of pioglitazone, metformin and flutamide.

Evaluation of instruments used in particle size analysis by using the sedimentation technique

International Nuclear Information System (INIS)

Elmasry, M.A.A.; Abdrahman, A.A.M.; Ahmed, A.Z.

2007-01-01

This study is carried out to evaluate the performance of some instruments in which the sedimentation technique is used for the determination of particle size distribution using Stoke's law. A mathematical formula has been developed to calculate the particle size distribution for different cases and the results were compared to the real ones. The results revealed unsatisfactory agreement between the calculated and the measured values. In addition, illogic results were obtained indicating that the instruments in which the sedimentation technique is used are not the proper ones to provide accurate measurements except for mono particle size cases. More above, the results obtained represent the sedimentation rate but not the particle size distribution.

Measurement of triboelectric charging of moving micro particles by means of an inductive cylindrical probe

International Nuclear Information System (INIS)

Nesterov, A; Loeffler, F; Koenig, K; Trunk, U; Leibe, K; Felgenhauer, T; Bischoff, F R; Breitling, F; Lindenstruth, V; Stadler, V; Hausmann, M

2007-01-01

We present a method based on induced currents in a cylindrical probe which allows analysis of the micro-particle charging processes in an aerosol. The micro particles were triboelectrically charged by passing through a dielectric tube coaxially mounted into the probe. The cylindrical probe enabled the quantification of particle charging without prior calibration of the probe. An analytic model was developed for the description of the measured induced currents and implemented into a computer simulation program. The combination of model simulations and an appropriate experimental setup revealed comprehensive data for the determination of the particles' electric charge against time of flight through the tube. In methodological proof of principle experiments, the formations of particle clouds with charges of different signs were observed using magnetite micro particles

Structure of Energetic Particle Mediated Shocks Revisited

International Nuclear Information System (INIS)

Mostafavi, P.; Zank, G. P.; Webb, G. M.

2017-01-01

The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

Structure of Energetic Particle Mediated Shocks Revisited

Energy Technology Data Exchange (ETDEWEB)

Mostafavi, P.; Zank, G. P. [Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Webb, G. M. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

2017-05-20

The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

Fission product Pd-SiC interaction in irradiated coated particle fuels

International Nuclear Information System (INIS)

Tiegs, T.N.

1980-04-01

Silicon carbide is the main barrier to fission product release from coated particle fuels. Consequently, degradation of the SiC must be minimized. Electron microprobe analysis has identified that palladium causes corrosion of the SiC in irradiated coated particles. Further ceramographic and electron microprobe examinations on irradiated particles with kernels ranging in composition from UO 2 to UC 2 , including PuO/sub 2 -x/ and mixed (Th, Pu) oxides, and in enrichment from 0.7 to 93.0% 235 U revealed that temperature is the major factor affecting the penetration rate of SiC by Pd. The effects of kernel composition, Pd concentration, other fission products, and SiC properties are secondary

Big Bang Day: 5 Particles - 5. The Next Particle

CERN Multimedia

Franck Close

2008-01-01

Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 5. The Next Particle The "sparticle" - a super symmetric partner to all the known particles could be the answer to uniting all the known particles and their interactions under one grand theoretical pattern of activity. But how do researchers know where to look for such phenomena and how do they know if they find them? Simon Singh reviews the next particle that physicists would like to find if the current particle theories are to ring true.

Magnetic rotational hysteresis study on spherical 85-160 nm Fe3O4 particles

Science.gov (United States)

Schmidbauer, E.

1988-05-01

Rotational hysteresis losses Wr were determined as a function of magnetic field H for dispensed spherical Fe3O4 particles of mean grain sizes 85 nm, 127 nm and 162 nm between 78 K and 294 K. The observed Wr-H curves are compared with theoretical curves for single domain particles. The analysed particles reveal centers of high magnetic anisotropy. Such centers can be of importance during the generation of a thermoremanent magnetization, as they may be the origin of enhanced magnetic stability.

Nuclear thermodynamics below particle threshold

International Nuclear Information System (INIS)

Schiller, A.; Agvaanluvsan, U.; Algin, E.; Bagheri, A.; Chankova, R.; Guttormsen, M.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Voinov, A.

2005-01-01

From a starting point of experimentally measured nuclear level densities, we discuss thermodynamical properties of nuclei below the particle emission threshold. Since nuclei are essentially mesoscopic systems, a straightforward generalization of macroscopic ensemble theory often yields unphysical results. A careful critique of traditional thermodynamical concepts reveals problems commonly encountered in mesoscopic systems. One of which is the fact that microcanonical and canonical ensemble theory yield different results, another concerns the introduction of temperature for small, closed systems. Finally, the concept of phase transitions is investigated for mesoscopic systems

Real-time aerosol photometer and optical particle counter comparison

International Nuclear Information System (INIS)

Santi, E.; Belosi, F.; Santachiara, G.; Prodi, F.; Berico, M.

2010-01-01

The paper presents the results of a comparison exercise among real-time aerosol samplers, based on different light scattering techniques. The comparison was carried out near to the ISAC institute in a box positioned inside the CNR research area in Bologna. Two nephelometers (Dust Trak from TSI, and Air Genius from Unitec) and an optical particle counter (ENVIRO-check from Grimm) were used for P M1 and P M10 fraction assessment. In the case of the optical particle counter, the particle number concentration in each size bin was also used. In parallel, two manual sampling lines were employed for reference (gravimetric) measurements. The results highlight different factor scales for the dust monitors, in comparison with gravimetric assessment, underlining the importance of a user calibration of such monitors as a function of the specific aerosol sampled. Moreover, the relative fluctuations of the hourly P M 10 and P M1 concentrations, against daily average concentrations, were studied in order to compare the ability of each sampler to follow changes in the aerosol size distribution. It was found that the photometers and optical particle counter revealed different behaviours. In the latter, a small increase in the particle concentration number in the coarse fraction gave a relatively high increase in the mass concentration that was not measured by the photometers. The explanation could be the relatively slight influence of a small particle number variation on the total scattered light for the photometers, unlike the case of the optical particle counter, where each particle contributes to the mass concentration. This aspect merits future research in order to better understand optical particle counter output used in P Mx monitoring activities.

Preparation and Characterization of Stable α-Synuclein Lipoprotein Particles.

Science.gov (United States)

Eichmann, Cédric; Campioni, Silvia; Kowal, Julia; Maslennikov, Innokentiy; Gerez, Juan; Liu, Xiaoxia; Verasdonck, Joeri; Nespovitaya, Nadezhda; Choe, Senyon; Meier, Beat H; Picotti, Paola; Rizo, Josep; Stahlberg, Henning; Riek, Roland

2016-04-15

Multiple neurodegenerative diseases are caused by the aggregation of the human α-Synuclein (α-Syn) protein. α-Syn possesses high structural plasticity and the capability of interacting with membranes. Both features are not only essential for its physiological function but also play a role in the aggregation process. Recently it has been proposed that α-Syn is able to form lipid-protein particles reminiscent of high-density lipoproteins. Here, we present a method to obtain a stable and homogeneous population of nanometer-sized particles composed of α-Syn and anionic phospholipids. These particles are called α-Syn lipoprotein (nano)particles to indicate their relationship to high-density lipoproteins formed by human apolipoproteins in vivo and of in vitro self-assembling phospholipid bilayer nanodiscs. Structural investigations of the α-Syn lipoprotein particles by circular dichroism (CD) and magic angle solid-state nuclear magnetic resonance (MAS SS-NMR) spectroscopy establish that α-Syn adopts a helical secondary structure within these particles. Based on cryo-electron microscopy (cryo-EM) and dynamic light scattering (DLS) α-Syn lipoprotein particles have a defined size with a diameter of ∼23 nm. Chemical cross-linking in combination with solution-state NMR and multiangle static light scattering (MALS) of α-Syn particles reveal a high-order protein-lipid entity composed of ∼8-10 α-Syn molecules. The close resemblance in size between cross-linked in vitro-derived α-Syn lipoprotein particles and a cross-linked species of endogenous α-Syn from SH-SY5Y human neuroblastoma cells indicates a potential functional relevance of α-Syn lipoprotein nanoparticles. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Classical relativistic constituent particles and composite-particle scattering

International Nuclear Information System (INIS)

King, M.J.

1984-01-01

A nonlocal Lagrangian formalism is developed to describe a classical many-particle system. The nonstandard Lagrangian is a function of a single parameter s which is not, in general, associated with the physical clock. The particles are constrained to be constituents of composite systems, which in turn can decompose into asymptotic composite states representing free observable particles. To demonstrate this, explicit models of composite-composite particle scattering are constructed. Space-time conservation laws are not imposed separately on the system, but follow upon requiring the constituents to ''pair up'' into free composites at s = +infinity,-infinity. One model is characterized by the appearance of an ''external'' zero-mass composite particle which participates in the scattering process without affecting the space-time conservation laws of the two-composite system. Initial conditions on the two incoming composite particles and the zero-mass participant determine the scattering angle and the final states of the two outgoing composite particles. Although the formalism is classical, the model displays some features usually associated with quantum field theory, such as particle scattering by means of constituent exchange, creation and annihilation of particles, and restriction of values of angular momentum

Irregular Magnetic Fields and Energetic Particles near the Termination Shock

International Nuclear Information System (INIS)

Giacalone, J.; Jokipii, J. R.

2004-01-01

The physics of magnetic field-line meandering and the associated energetic-particle transport in the outer heliosphere is discussed. We assume that the heliospheric magnetic field, which is frozen into the solar-wind plasma, is composed of both an average and random component. The power in the random component is dominated by spatial scales that are very large (by a few orders of magnitude) compared to the shock thickness. The results from recent numerical simulations are presented. They reveal a number of characteristics which may be related to recent Voyager 1 observations of energetic particles and fields. For instance, low-energy (tens of keV) particles are seen well upstream of the shock that also have large pitch-angle anisotropies. Furthermore, low-energy particles are readily accelerated by the shock, even though their mean-free paths are very large compared to their gyroradii. When averaging over the entire system, the downstream spectra are qualitatively consistent with the theory of diffusive shock acceleration

A physics-motivated Centroidal Voronoi Particle domain decomposition method

Energy Technology Data Exchange (ETDEWEB)

Fu, Lin, E-mail: lin.fu@tum.de; Hu, Xiangyu Y., E-mail: xiangyu.hu@tum.de; Adams, Nikolaus A., E-mail: nikolaus.adams@tum.de

2017-04-15

In this paper, we propose a novel domain decomposition method for large-scale simulations in continuum mechanics by merging the concepts of Centroidal Voronoi Tessellation (CVT) and Voronoi Particle dynamics (VP). The CVT is introduced to achieve a high-level compactness of the partitioning subdomains by the Lloyd algorithm which monotonically decreases the CVT energy. The number of computational elements between neighboring partitioning subdomains, which scales the communication effort for parallel simulations, is optimized implicitly as the generated partitioning subdomains are convex and simply connected with small aspect-ratios. Moreover, Voronoi Particle dynamics employing physical analogy with a tailored equation of state is developed, which relaxes the particle system towards the target partition with good load balance. Since the equilibrium is computed by an iterative approach, the partitioning subdomains exhibit locality and the incremental property. Numerical experiments reveal that the proposed Centroidal Voronoi Particle (CVP) based algorithm produces high-quality partitioning with high efficiency, independently of computational-element types. Thus it can be used for a wide range of applications in computational science and engineering.

Preparation, characterization and nonlinear absorption studies of cuprous oxide nanoclusters, micro-cubes and micro-particles

Science.gov (United States)

Sekhar, H.; Narayana Rao, D.

2012-07-01

Cuprous oxide nanoclusters, micro-cubes and micro-particles were successfully synthesized by reducing copper(II) salt with ascorbic acid in the presence of sodium hydroxide via a co-precipitation method. The X-ray diffraction and FTIR studies revealed that the formation of pure single-phase cubic. Raman and EPR spectral studies show the presence of CuO in as-synthesized powders of Cu2O. Transmission electron microscopy and field emission scanning electron microscopy data revealed that the morphology evolves from nanoclusters to micro-cubes and micro-particles by increasing the concentration of NaOH. Linear optical measurements show absorption peak maximum shifts towards red with changing morphology from nanoclusters to micro-cubes and micro-particles. The nonlinear optical properties were studied using open aperture Z-scan technique with 532 nm 6 ns laser pulses. Samples-exhibited both saturable as well as reverse saturable absorption. Due to confinement effects (enhanced band gap), we observed enhanced nonlinear absorption coefficient (β) in the case of nanoclusters compared to their micro-cubes and micro-particles.

Quantitative theory of channeling particle diffusion in transverse energy in the presence of nuclear scattering and direct evaluation of dechanneling length

Energy Technology Data Exchange (ETDEWEB)

Tikhomirov, Victor V. [Belarusian State University, Institute for Nuclear Problems, Minsk (Belarus)

2017-07-15

A refined equation for channeling particle diffusion in transverse energy taking into consideration large-angle scattering by nuclei is suggested. This equation is reduced to the Sturm-Liouville problem, allowing one to reveal both the origin and the limitations of the dechanneling length notion. The values of the latter are evaluated for both positively and negatively charged particles of various energies. New features of the dechanneling dynamics of positively charged particles are also revealed. First, it is demonstrated that the dechanneling length notion is completely inapplicable for their nuclear dechanneling process. Second, the effective electron dechanneling length of positively charged particle varies more than twice converging to a constant asymptotic value only at the depth exceeding the latter. (orig.)

Particle resuspension due to human walking

International Nuclear Information System (INIS)

Mana, Zakaria

2014-01-01

In nuclear facilities, during normal operations in controlled areas, workers could be exposed to radioactive aerosols (1 μm ≤ dp ≤ 10 μm). One of the airborne contamination sources is particles that are initially seeded on the floor and could be removed by workers while they are walking. During the outage of EDF nuclear facilities, there is a resuspension of some radionuclides in aerosol form (1 μm ≤ dp ≤ 10 μm). Since the number of co-activity will increase in reactors buildings of EDF, it becomes important to understand particle resuspension due to the activity of the operators to reduce their radiation exposure. The purpose of this Ph.D thesis is to quantify the resuspension of particles due to the progress of operators on a contaminated soil. Thus, the approach is to combine an aerodynamic resuspension model with numerical calculations of flow under a shoe, and then to characterize experimentally some input parameters of the model (particle diameter, adhesion forces, shoes motion). The resuspension model Rock'n'Roll proposed by Reeks and Hall (2001) was chosen because it describes physically the resuspension mechanism and because it is based on the moment of forces applied to a particle. This model requires two input parameters such as friction velocity and adhesion forces distribution applied on each particle. Regarding the first argument, numerical simulations were carried on using the ANSYS CFX software applied to a safety shoe in motion (digitized by 3D CAO); the mapping of friction velocity shows values of about 1 m.s -1 for an angular average velocity of 200 degrees.s -1 . As regards the second parameter, AFM (Atomic Force Microscopy) measurements were carried out with alumina and cobalt oxide particles in contact with epoxy surfaces representative of those encountered in EDF power plants. AFM provides the distribution of adhesion forces and reveals a much lower value than what can be calculated theoretically using JKR model (Johnson

Inward particle transport at high collisionality in the Experimental Advanced Superconducting Tokamak

International Nuclear Information System (INIS)

Wang, G. Q.; Ma, J.; Weiland, J.; Zang, Q.

2013-01-01

We have made the first drift wave study of particle transport in the Experimental Advanced Superconducting Tokamak (Wan et al., Nucl. Fusion 49, 104011 (2009)). The results reveal that collisions make the particle flux more inward in the high collisionality regime. This can be traced back to effects that are quadratic in the collision frequency. The particle pinch is due to electron trapping which is not very efficient in the high collisionality regime so the approach to equilibrium is slow. We have included also the electron temperature gradient (ETG) mode to give the right electron temperature gradient, since the Trapped Electron Mode (TE mode) is weak in this regime. However, at the ETG mode number ions are Boltzmann distributed so the ETG mode does not give particle transport

[The interaction of soil micromycetes with "hot" particles in a model system].

Science.gov (United States)

Zhdanova, N N; Lashko, T N; Redchits, T I; Vasilevskaia, A I; Borisiuk, L G; Siniavskaia, O I; Gavriliuk, V I; Muzalev, P N

1991-01-01

A model system which permits observing for a long time and fixing interaction of fungi with a radiation source has been created on the basis of an isolated "hot" particle, deficient mineral medium (saccharose content 60 mg/l) and suspension of fungal conidia. Five species (six strains) of micromycetes isolated from radionuclide-contaminated soils and fifteen "hot" particles have been tested. It has been found out for the first time that Cladosporium cladosporioides and Penicillium roseo-purpureum are able actively overgrow "hot" particles whose radioactivity did not exceed 3.1-1.0(-7) Ci by gamma-spectrum and to destroy them 50-150 days later. Certain changes in morphology of fungi-destructors of "hot" particles are revealed. A problem on ecological significance of the found phenomenon is discussed.

Interaction of Multiple Particles with a Solidification Front: From Compacted Particle Layer to Particle Trapping.

Science.gov (United States)

Saint-Michel, Brice; Georgelin, Marc; Deville, Sylvain; Pocheau, Alain

2017-06-13

The interaction of solidification fronts with objects such as particles, droplets, cells, or bubbles is a phenomenon with many natural and technological occurrences. For an object facing the front, it may yield various fates, from trapping to rejection, with large implications regarding the solidification pattern. However, whereas most situations involve multiple particles interacting with each other and the front, attention has focused almost exclusively on the interaction of a single, isolated object with the front. Here we address experimentally the interaction of multiple particles with a solidification front by performing solidification experiments of a monodisperse particle suspension in a Hele-Shaw cell with precise control of growth conditions and real-time visualization. We evidence the growth of a particle layer ahead of the front at a close-packing volume fraction, and we document its steady-state value at various solidification velocities. We then extend single-particle models to the situation of multiple particles by taking into account the additional force induced on an entering particle by viscous friction in the compacted particle layer. By a force balance model this provides an indirect measure of the repelling mean thermomolecular pressure over a particle entering the front. The presence of multiple particles is found to increase it following a reduction of the thickness of the thin liquid film that separates particles and front. We anticipate the findings reported here to provide a relevant basis to understand many complex solidification situations in geophysics, engineering, biology, or food engineering, where multiple objects interact with the front and control the resulting solidification patterns.

The acceleration and propagation of solar energetic particles

International Nuclear Information System (INIS)

Dalla, Silvia

2004-01-01

During flares and coronal mass ejections at the Sun, ions and electrons can be accelerated to high energies. They can escape from the solar corona into interplanetary space, and be detected by instruments on board spacecraft. This paper will review measurements of these solar energetic particles (SEPs) and models of their acceleration and propagation.It is generally agreed that SEP flux enhancements fall into two distinct classes: the so-called impulsive events, thought to originate in solar flares, and gradual events, thought to be the result of acceleration at the shock driven through the corona and interplanetary space by coronal mass ejections. A fundamental assumption of this model for SEPs is that particles' guiding centers propagate essentially parallel to the interplanetary magnetic field lines, and cross-field particle diffusion is negligible.The recent passage of the Ulysses spacecraft over the solar poles provided the first ever measurements of SEPs out of the ecliptic plane. Analysis of these data has revealed several fundamental differences with respect to the near-ecliptic measurements, such as large delays in particle arrival and in fluxes reaching their peak value. It will be shown that the current model of SEP acceleration and propagation does not account for the Ulysses results, which would more easily be explained by efficient cross-field diffusion of energetic particles

Size-selective sorting in bubble streaming flows: Particle migration on fast time scales

Science.gov (United States)

Thameem, Raqeeb; Rallabandi, Bhargav; Hilgenfeldt, Sascha

2015-11-01

Steady streaming from ultrasonically driven microbubbles is an increasingly popular technique in microfluidics because such devices are easily manufactured and generate powerful and highly controllable flows. Combining streaming and Poiseuille transport flows allows for passive size-sensitive sorting at particle sizes and selectivities much smaller than the bubble radius. The crucial particle deflection and separation takes place over very small times (milliseconds) and length scales (20-30 microns) and can be rationalized using a simplified geometric mechanism. A quantitative theoretical description is achieved through the application of recent results on three-dimensional streaming flow field contributions. To develop a more fundamental understanding of the particle dynamics, we use high-speed photography of trajectories in polydisperse particle suspensions, recording the particle motion on the time scale of the bubble oscillation. Our data reveal the dependence of particle displacement on driving phase, particle size, oscillatory flow speed, and streaming speed. With this information, the effective repulsive force exerted by the bubble on the particle can be quantified, showing for the first time how fast, selective particle migration is effected in a streaming flow. We acknowledge support by the National Science Foundation under grant number CBET-1236141.

Dynamics of spherical metallic particles in cylinder electrostatic separators/purifiers.

Science.gov (United States)

Lu, Hong-Zhou; Li, Jia; Guo, Jie; Xu, Zhen-Ming

2008-08-15

This paper presents a theoretical analysis of the dynamics of spherical metallic particles in electrostatic separators/purifiers (ESPs). The particle equations of motion are numerically solved in two dimensions using a computational algorithm. The ESPs consist of a pair of conductor cylinder electrodes. The upper cylinder is energized by HVdc, while the lower one is grounded and fixed horizontally on a revolvable axis. Some phenomena and aspects of separation process are explained and depicted including lifting off, impact, "motion collapse" and "sudden bouncing". The results reveal that the several phenomena depend on initial position, radius and density of the particle, curvature of the cylinder electrodes, distance between the electrodes and amplitude of the applied voltage. Optimization of the parameters is presented in order to get better separation/purification processes.

ECG Denoising Using Marginalized Particle Extended Kalman Filter With an Automatic Particle Weighting Strategy.

Science.gov (United States)

Hesar, Hamed Danandeh; Mohebbi, Maryam

2017-05-01

In this paper, a model-based Bayesian filtering framework called the "marginalized particle-extended Kalman filter (MP-EKF) algorithm" is proposed for electrocardiogram (ECG) denoising. This algorithm does not have the extended Kalman filter (EKF) shortcoming in handling non-Gaussian nonstationary situations because of its nonlinear framework. In addition, it has less computational complexity compared with particle filter. This filter improves ECG denoising performance by implementing marginalized particle filter framework while reducing its computational complexity using EKF framework. An automatic particle weighting strategy is also proposed here that controls the reliance of our framework to the acquired measurements. We evaluated the proposed filter on several normal ECGs selected from MIT-BIH normal sinus rhythm database. To do so, artificial white Gaussian and colored noises as well as nonstationary real muscle artifact (MA) noise over a range of low SNRs from 10 to -5 dB were added to these normal ECG segments. The benchmark methods were the EKF and extended Kalman smoother (EKS) algorithms which are the first model-based Bayesian algorithms introduced in the field of ECG denoising. From SNR viewpoint, the experiments showed that in the presence of Gaussian white noise, the proposed framework outperforms the EKF and EKS algorithms in lower input SNRs where the measurements and state model are not reliable. Owing to its nonlinear framework and particle weighting strategy, the proposed algorithm attained better results at all input SNRs in non-Gaussian nonstationary situations (such as presence of pink noise, brown noise, and real MA). In addition, the impact of the proposed filtering method on the distortion of diagnostic features of the ECG was investigated and compared with EKF/EKS methods using an ECG diagnostic distortion measure called the "Multi-Scale Entropy Based Weighted Distortion Measure" or MSEWPRD. The results revealed that our proposed

Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

International Nuclear Information System (INIS)

Uudeküll, Peep; Kozlova, Jekaterina; Mändar, Hugo; Link, Joosep; Sihtmäe, Mariliis; Käosaar, Sandra; Blinova, Irina; Kasemets, Kaja; Kahru, Anne; Stern, Raivo; Tätte, Tanel; Kukli, Kaupo; Tamm, Aile

2017-01-01

Spherical nickel particles with size in the range of 100–400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

Energy Technology Data Exchange (ETDEWEB)

Uudeküll, Peep, E-mail: peep.uudekull@ut.ee [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Kozlova, Jekaterina; Mändar, Hugo [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Link, Joosep [Laboratory of Chemical Physics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Sihtmäe, Mariliis [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Käosaar, Sandra [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Faculty of Chemical and Materials Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Blinova, Irina; Kasemets, Kaja; Kahru, Anne [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Stern, Raivo [Laboratory of Chemical Physics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Tätte, Tanel [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Kukli, Kaupo [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Tamm, Aile [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia)

2017-05-01

Spherical nickel particles with size in the range of 100–400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

Individual aerosol particles in and below clouds along a Mt. Fuji slope: Modification of sea-salt-containing particles by in-cloud processing

Science.gov (United States)

Ueda, S.; Hirose, Y.; Miura, K.; Okochi, H.

2014-02-01

Sizes and compositions of atmospheric aerosol particles can be altered by in-cloud processing by absorption/adsorption of gaseous and particulate materials and drying of aerosol particles that were formerly activated as cloud condensation nuclei. To elucidate differences of aerosol particles before and after in-cloud processing, aerosols were observed along a slope of Mt. Fuji, Japan (3776 m a.s.l.) during the summer in 2011 and 2012 using a portable laser particle counter (LPC) and an aerosol sampler. Aerosol samples for analyses of elemental compositions were obtained using a cascade impactor at top-of-cloud, in-cloud, and below-cloud altitudes. To investigate composition changes via in-cloud processing, individual particles (0.5-2 μm diameter) of samples from five cases (days) collected at different altitudes under similar backward air mass trajectory conditions were analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. For most cases (four cases), most particles at all altitudes mainly comprised sea salts: mainly Na with some S and/or Cl. Of those, in two cases, sea-salt-containing particles with Cl were found in below-cloud samples, although sea-salt-containing particles in top-of-cloud samples did not contain Cl. This result suggests that Cl in the sea salt was displaced by other cloud components. In the other two cases, sea-salt-containing particles on samples at all altitudes were without Cl. However, molar ratios of S to Na (S/Na) of the sea-salt-containing particles of top-of-cloud samples were higher than those of below-cloud samples, suggesting that sulfuric acid or sulfate was added to sea-salt-containing particles after complete displacement of Cl by absorption of SO2 or coagulation with sulfate. The additional volume of sulfuric acid in clouds for the two cases was estimated using the observed S/Na values of sea-salt-containing particles. The estimation revealed that size changes by in

In vitro protease cleavage and computer simulations reveal the HIV-1 capsid maturation pathway

Science.gov (United States)

Ning, Jiying; Erdemci-Tandogan, Gonca; Yufenyuy, Ernest L.; Wagner, Jef; Himes, Benjamin A.; Zhao, Gongpu; Aiken, Christopher; Zandi, Roya; Zhang, Peijun

2016-12-01

HIV-1 virions assemble as immature particles containing Gag polyproteins that are processed by the viral protease into individual components, resulting in the formation of mature infectious particles. There are two competing models for the process of forming the mature HIV-1 core: the disassembly and de novo reassembly model and the non-diffusional displacive model. To study the maturation pathway, we simulate HIV-1 maturation in vitro by digesting immature particles and assembled virus-like particles with recombinant HIV-1 protease and monitor the process with biochemical assays and cryoEM structural analysis in parallel. Processing of Gag in vitro is accurate and efficient and results in both soluble capsid protein and conical or tubular capsid assemblies, seemingly converted from immature Gag particles. Computer simulations further reveal probable assembly pathways of HIV-1 capsid formation. Combining the experimental data and computer simulations, our results suggest a sequential combination of both displacive and disassembly/reassembly processes for HIV-1 maturation.

Enhanced stopping of macro-particles in particle-in-cell simulations

International Nuclear Information System (INIS)

May, J.; Tonge, J.; Ellis, I.; Mori, W. B.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.; Ren, C.

2014-01-01

We derive an equation for energy transfer from relativistic charged particles to a cold background plasma appropriate for finite-size particles that are used in particle-in-cell simulation codes. Expressions for one-, two-, and three-dimensional particles are presented, with special attention given to the two-dimensional case. This energy transfer is due to the electric field of the wake set up in the background plasma by the relativistic particle. The enhanced stopping is dependent on the q 2 /m, where q is the charge and m is the mass of the relativistic particle, and therefore simulation macro-particles with large charge but identical q/m will stop more rapidly. The stopping power also depends on the effective particle shape of the macro-particle. These conclusions are verified in particle-in-cell simulations. We present 2D simulations of test particles, relaxation of high-energy tails, and integrated fast ignition simulations showing that the enhanced drag on macro-particles may adversely affect the results of these simulations in a wide range of high-energy density plasma scenarios. We also describe a particle splitting algorithm which can potentially overcome this problem and show its effect in controlling the stopping of macro-particles

Confined Diffusion Without Fences of a G-Protein-Coupled Receptor as Revealed by Single Particle Tracking

Science.gov (United States)

Daumas, Frédéric; Destainville, Nicolas; Millot, Claire; Lopez, André; Dean, David; Salomé, Laurence

2003-01-01

Single particle tracking is a powerful tool for probing the organization and dynamics of the plasma membrane constituents. We used this technique to study the μ-opioid receptor belonging to the large family of the G-protein-coupled receptors involved with other partners in a signal transduction pathway. The specific labeling of the receptor coupled to a T7-tag at its N-terminus, stably expressed in fibroblastic cells, was achieved by colloidal gold coupled to a monoclonal anti T7-tag antibody. The lateral movements of the particles were followed by nanovideomicroscopy at 40 ms time resolution during 2 min with a spatial precision of 15 nm. The receptors were found to have either a slow or directed diffusion mode (10%) or a walking confined diffusion mode (90%) composed of a long-term random diffusion and a short-term confined diffusion, and corresponding to a diffusion confined within a domain that itself diffuses. The results indicate that the confinement is due to an effective harmonic potential generated by long-range attraction between the membrane proteins. A simple model for interacting membrane proteins diffusion is proposed that explains the variations with the domain size of the short-term and long-term diffusion coefficients. PMID:12524289

Elementary particles and particle interactions

International Nuclear Information System (INIS)

Bethge, K.; Schroeder, U.E.

1986-01-01

This book is a textbook for an introductory course of elementary particle physics. After a general introduction the symmetry principles governing the interactions of elementary particles are discussed. Then the phenomenology of the electroweak and strong interactions are described together with a short introduction to the Weinberg-Salam theory respectively to quantum chromodynamics. Finally a short outlook is given to grand unification with special regards to SU(5) and cosmology in the framework of the current understanding of the fundamental principles of nature. In the appendix is a table of particle properties and physical constants. (HSI) [de

Rare particles

International Nuclear Information System (INIS)

Kutschera, W.

1984-01-01

The use of Accelerator Mass Spectrometry (AMS) to search for hypothetical particles and known particles of rare processes is discussed. The hypothetical particles considered include fractionally charged particles, anomalously heavy isotopes, and superheavy elements. The known particles produced in rare processes discussed include doubly-charged negative ions, counting neutrino-produced atoms in detectors for solar neutrino detection, and the spontaneous emission of 14 C from 223 Ra. 35 references

Statistical and direct decay of high-lying single-particle excitations

International Nuclear Information System (INIS)

Gales, S.

1993-01-01

Transfer reactions induced by hadronic probes at intermediate energies have revealed a rich spectrum of high-lying excitations embedded in the nuclear continuum. The investigation of their decay properties is believed to be a severe test of their microscopic structure as predicted by microscopic nuclear models. In addition the degree of damping of these simple modes in the nuclear continuum can be obtained by means of the measured particle (n,p) decay branching ratios. The neutron and proton decay studies of high-lying single-particle states in heavy nuclei are presented. (author). 13 refs., 9 figs

Quantum Dynamics of Test Particle in Curved Space-Time

International Nuclear Information System (INIS)

Piechocki, W.

2002-01-01

To reveal the nature of space-time singularities of removable type we examine classical and quantum dynamics of a free particle in the Sitter type spacetimes. Consider space-times have different topologies otherwise are isometric. Our systems are integrable and we present analytic solutions of the classical dynamics. We quantize the systems by making use of the group theoretical method: we find an essentially self-adjoint representation of the algebra of observables integrable to the irreducible unitarity representation of the symmetry group of each consider gravitational system. The massless particle dynamics is obtained in the zero-mass limit of the massive case. Global properties of considered gravitational systems are of primary importance for the quantization procedure. Systems of a particle in space-times with removable singularities appear to be quantizable. We give specific proposal for extension of our analysis to space-times with essential type singularities. (author)

The observation of nitric acid-containing particles in the tropical lower stratosphere

Directory of Open Access Journals (Sweden)

P. J. Popp

2006-01-01

Full Text Available Airborne in situ measurements over the eastern Pacific Ocean in January 2004 have revealed a new category of nitric acid (HNO3-containing particles in the tropical lower stratosphere. These particles are most likely composed of nitric acid trihydrate (NAT. They were intermittently observed in a narrow layer above the tropopause (18±0.1 km and over a broad geographic extent (>1100 km. In contrast to the background liquid sulfate aerosol, these particles are solid, much larger (1.7-4.7 µm vs. 0.1µm in diameter, and significantly less abundant (-4 cm-3 vs. 10 cm-3. Microphysical trajectory models suggest that the NAT particles grow over a 6-14 day period in supersaturated air that remains close to the tropical tropopause and might be a common feature in the tropics. The small number density of these particles implies a highly selective or slow nucleation process. Understanding the formation of solid NAT particles in the tropics could improve our understanding of stratospheric nucleation processes and, therefore, dehydration and denitrification.

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

Application of CR-39 microfilm for rapid discrimination between alpha-particle sources

Energy Technology Data Exchange (ETDEWEB)

Dwaikat, Nidal; Al-karmi, Anan M. [Dept. of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

2017-06-15

This work presents a new technique for discriminating between alpha particles of different energy levels. In a first study, two groups of alpha particles emitted from radium-226 and americium-241 sources were successfully separated using a CR-39 microfilm of appropriate thickness. This thickness was adjusted by chemical etching before and after irradiation so that lower-energy particles were stopped within the detector, while higher-energy particles were revealed on the back side of the detector. The number of tracks on the front side of the microfilm represented all alpha particles incident on that side from the two sources. However, the number of tracks on the back side of the microfilm represented only the long-range alpha particles of higher energy that arrived at that side. Therefore, by subtracting the number of tracks on the back side from the number of tracks on the front side, one could easily determine the number of tracks for the short-range alpha particles of lower energy that remained embedded in the microfilm. Discrimination of the two energy levels is thus achieved in a simple, fast, and reliable process.

Shape oscillations of elastic particles in shear flow.

Science.gov (United States)

Subramaniam, Dhananjay Radhakrishnan; Gee, David J

2016-09-01

Particle suspensions are common to biological fluid flows; for example, flow of red- and white-blood cells, and platelets. In medical technology, current and proposed methods for drug delivery use membrane-bounded liquid capsules for transport via the microcirculation. In this paper, we consider a 3D linear elastic particle inserted into a Newtonian fluid and investigate the time-dependent deformation using a numerical simulation. Specifically, a boundary element technique is used to investigate the motion and deformation of initially spherical or spheroidal particles in bounded linear shear flow. The resulting deformed shapes reveal a steady-state profile that exhibits a 'tank-treading' motion for initially spherical particles. Wall effects on particle trajectory are seen to include a modified Jeffrey׳s orbit for spheroidal inclusions with a period that varies inversely with the strength of the shear flow. Alternately, spheroidal inclusions may exhibit either a 'tumbling' or 'trembling' motion depending on the initial particle aspect ratio and the capillary number (i.e., ratio of fluid shear to elastic restoring force). We find for a capillary number of 0.1, a tumbling mode transitions to a trembling mode at an aspect ratio of 0.87 (approx.), while for a capillary number of 0.2, this transition takes place at a lower aspect ratio. These oscillatory modes are consistent with experimental observations involving similarly shaped vesicles and thus serves to validate the use of a simple elastic constitutive model to perform relevant physiological flow calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Particle film affects black pecan aphid (Homoptera: Aphididae) on pecan.

Science.gov (United States)

Cottrell, Ted E; Wood, Bruce W; Reilly, Charles C

2002-08-01

Three species of aphids attack pecan foliage, Carya illinoensis (Wang.) K. Koch, and cause economic damage. We tested a kaolin-based particle film against one of these aphid species, black pecan aphid, Melanocallis caryaefoliae (Davis). Effect of particle film on host selection, adult mortality, and production of nymphs by M. caryaefoliae was tested on seedling pecans in the laboratory. Fewer M. caryaefoliae adults selected treated foliage compared with untreated foliage. A higher percentage of adults that did select treated foliage were recovered from upper leaf surfaces compared with the percentage of adults recovered from upper leaf surfaces of untreated leaves. Observations with a microscope revealed an accumulation of particle film on aphid body parts, especially on tarsi, and strongly suggests that aphid mobility was restricted. Adult mortality was higher on treated foliage and led to an overall decrease in production of nymphs on those seedlings. In addition, we measured spectral properties of treated seedling pecan foliage. Light reflectance by treated foliage was increased and absorptance decreased compared with control foliage whereas transmittance of light through control and particle film-treated leaves was similar. We did not detect any phytotoxic effect on pecan due to application of particle film.

Optimization of Iron Oxide Tracer Synthesis for Magnetic Particle Imaging

Directory of Open Access Journals (Sweden)

Sabina Ziemian

2018-03-01

Full Text Available The optimization of iron oxide nanoparticles as tracers for magnetic particle imaging (MPI alongside the development of data acquisition equipment and image reconstruction techniques is crucial for the required improvements in image resolution and sensitivity of MPI scanners. We present a large-scale water-based synthesis of multicore superparamagnetic iron oxide nanoparticles stabilized with dextran (MC-SPIONs. We also demonstrate the preparation of single core superparamagnetic iron oxide nanoparticles in organic media, subsequently coated with a poly(ethylene glycol gallic acid polymer and phase transferred to water (SC-SPIONs. Our aim was to obtain long-term stable particles in aqueous media with high MPI performance. We found that the amplitude of the third harmonic measured by magnetic particle spectroscopy (MPS at 10 mT is 2.3- and 5.8-fold higher than Resovist for the MC-SPIONs and SC-SPIONs, respectively, revealing excellent MPI potential as compared to other reported MPI tracer particle preparations. We show that the reconstructed MPI images of phantoms using optimized multicore and specifically single-core particles are superior to that of commercially available Resovist, which we utilize as a reference standard, as predicted by MPS.

New developments in image-based characterization of coated particle nuclear fuel

Science.gov (United States)

Price, Jeffery R.; Aykac, Deniz; Hunn, John D.; Kercher, Andrew K.; Morris, Robert N.

2006-02-01

We describe in this paper new developments in the characterization of coated particle nuclear fuel using optical microscopy and digital imaging. As in our previous work, we acquire optical imagery of the fuel pellets in two distinct manners that we refer to as shadow imaging and cross-sectional imaging. In shadow imaging, particles are collected in a single layer on an optically transparent dish and imaged using collimated back-lighting to measure outer surface characteristics only. In cross-sectional imaging, particles are mounted in acrylic epoxy and polished to near-center to reveal the inner coating layers for measurement. For shadow imaging, we describe a curvaturebased metric that is computed from the particle boundary points in the FFT domain using a low-frequency parametric representation. We also describe how missing boundary points are approximated using band-limited interpolation so that the FFT can be applied. For cross-section imaging, we describe a new Bayesian-motivated segmentation scheme as well as a new technique to correct layer measurements for the fact that we cannot observe the true mid-plane of the approximately spherical particles.

Sediment particle entrainment in an obstructed annular

Energy Technology Data Exchange (ETDEWEB)

Loureiro, Bruno Venturini; Siqueira, Renato do Nascimento [Faculdade do Centro Leste (UCL), Serra, ES (Brazil). Lab. de Fenomenos de Transporte], e-mail: brunovl@ucl.br, e-mail: renatons@ucl.br

2006-07-01

Flow in an annular region with internal cylinder rotation is a classic problem in fluid mechanics and has been widely studied. Besides its importance as a fundamental problem, flow in annular regions has several practical applications. This project was motivated by an application of this kind of flow to the drilling of oil and gas wells. In this work, an erosion apparatus was constructed in order to study the effect of the internal cylinder rotation on particle entrainment in an obstructed annular space and bed package as well. The study also analyzed the influence of height of the particles bed on the process performance. The experiment was designed so that the internal cylinder rotation could be measured by an encoder. The fluid temperature was measured by a thermocouple and the experiments were carried out at the temperature of 25 deg C. The study revealed that the particle entrainment for the height of the bed that is close to the center of the cylinders is negligible and the internal cylinder rotation provokes the movement and packing of the bed. For lower height of the bed, with same dimension of the annular gap, the particle entrainment process was satisfactory and the bed compaction was smaller than in the previous case, leading to a more efficient cleaning process in the annular space. (author)

Detection of low-energy antinuclei in space using an active-target particle detector

Energy Technology Data Exchange (ETDEWEB)

Poeschl, Thomas; Greenwald, Daniel; Konorov, Igor; Paul, Stephan [Physics Department E18, Technische Universitaet Muenchen (Germany); Losekamm, Martin [Physics Department E18, Technische Universitaet Muenchen (Germany); Institute of Astronautics, Technische Universitaet Muenchen (Germany)

2015-07-01

Measuring antimatter in space excellently probes various astrophysical processes. The abundances and energy spectra of antiparticles reveal a lot about the creation and propagation of cosmic-ray particles in the universe. Abnormalities in their spectra can reveal exotic sources or inaccuracies in our understanding of the involved processes. The measurement of antiprotons and the search for antideuterons and antihelium are optimal at low kinetic energies since background from high-energy cosmic-ray collisions is low. For this reason, we are developing an active-target particle detector capable of detecting ions and anti-ions in the energy range of 30-100 MeV per nucleon. The detector consists of 900 scintillating fibers coupled to silicon photomultipliers and is designed to operate on nanosatellites. The primary application of the detector will be the Antiproton Flux in Space (AFIS) mission, whose goal is the measurement of geomagnetically trapped antiprotons inside Earth's inner radiation belt. In this talk, we explain our particle identification technique and present results from first in-beam measurements with a prototype.

Entanglement between particle partitions in itinerant many-particle states

NARCIS (Netherlands)

Haque, M.; Zozulya, O.S.; Schoutens, K.

2009-01-01

We review 'particle-partitioning entanglement' for itinerant many-particle systems. This is defined as the entanglement between two subsets of particles making up the system. We identify generic features and mechanisms of particle entanglement that are valid over whole classes of itinerant quantum

Motion and twisting of magnetic particles ingested by alveolar macrophages in non-smokers and smokers: Implementation of viscoelasticity

International Nuclear Information System (INIS)

Moeller, Winfried; Felten, Kathrin; Kohlhaeufl, Martin; Haeussinger, Karl; Kreyling, Wolfgang G.

2007-01-01

Ferrimagnetic iron oxide particles were inhaled by 17 healthy volunteers (9 non-smokers, 8 smokers), and the retained particles were magnetized and detected by a SQUID. Stochastic particle transport due to cytoskeletal reorganizations within macrophages (relaxation) and directed particle motion in a weak magnetic twisting field were investigated with respect to viscous and elastic properties of the cytoskeleton. Relaxation and cytoskeletal stiffness were not influenced by cigarette smoking. Relaxation and particle twisting revealed a non-Newtonian viscosity with a pure viscous and a viscoelastic compartment. Viscous and elastic data obtained from relaxation correlated with particle twisting, indicating that the proposed simple model is a reasonable approximation of cytoskeletal mechanical properties

Single-particle fusion of influenza viruses reveals complex interactions with target membranes

Science.gov (United States)

van der Borg, Guus; Braddock, Scarlett; Blijleven, Jelle S.; van Oijen, Antoine M.; Roos, Wouter H.

2018-05-01

The first step in infection of influenza A virus is contact with the host cell membrane, with which it later fuses. The composition of the target bilayer exerts a complex influence on both fusion efficiency and time. Here, an in vitro, single-particle approach is used to study this effect. Using total internal reflection fluorescence (TIRF) microscopy and a microfluidic flow cell, the hemifusion of single virions is visualized. Hemifusion efficiency and kinetics are studied while altering target bilayer cholesterol content and sialic-acid donor. Cholesterol ratios tested were 0%, 10%, 20%, and 40%. Sialic-acid donors GD1a and GYPA were used. Both cholesterol ratio and sialic-acid donors proved to have a significant effect on hemifusion efficiency. Furthermore, comparison between GD1a and GYPA conditions shows that the cholesterol dependence of the hemifusion time is severely affected by the sialic-acid donor. Only GD1a shows a clear increasing trend in hemifusion efficiency and time with increasing cholesterol concentration of the target bilayer with maximum rates for GD1A and 40% cholesterol. Overall our results show that sialic acid donor and target bilayer composition should be carefully chosen, depending on the desired hemifusion time and efficiency in the experiment.

The response of macrophages to titanium particles is determined by macrophage polarization.

Science.gov (United States)

Pajarinen, Jukka; Kouri, Vesa-Petteri; Jämsen, Eemeli; Li, Tian-Fang; Mandelin, Jami; Konttinen, Yrjö T

2013-11-01

Aseptic loosening of total joint replacements is driven by the reaction of macrophages to foreign body particles released from the implant. It was hypothesized that the macrophages' response to these particles is dependent, in addition to particle characteristics and contaminating biomolecules, on the state of macrophage polarization as determined by the local cytokine microenvironment. To test this hypothesis we differentiated M1 and M2 macrophages from human peripheral blood monocytes and compared their responses to titanium particles using genome-wide microarray analysis and a multiplex cytokine assay. In comparison to non-activated M0 macrophages, the overall chemotactic and inflammatory responses to titanium particles were greatly enhanced in M1 macrophages and effectively suppressed in M2 macrophages. In addition, the genome-wide approach revealed several novel, potentially osteolytic, particle-induced mediators, and signaling pathway analysis suggested the involvement of toll-like and nod-like receptor signaling in particle recognition. It is concluded that the magnitude of foreign body reaction caused by titanium particles is dependent on the state of macrophage polarization. Thus, by limiting the action of M1 polarizing factors, e.g. bacterial biofilm formation, in peri-implant tissues and promoting M2 macrophage polarization by biomaterial solutions or pharmacologically, it might be possible to restrict wear-particle-induced inflammation and osteolysis. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Exclusion of mRNPs and ribosomal particles from a thin zone beneath the nuclear envelope revealed upon inhibition of transport

International Nuclear Information System (INIS)

Kylberg, Karin; Bjoerk, Petra; Fomproix, Nathalie; Ivarsson, Birgitta; Wieslander, Lars; Daneholt, Bertil

2010-01-01

We have studied the nucleocytoplasmic transport of a specific messenger RNP (mRNP) particle, named Balbiani ring (BR) granule, and ribosomal RNP (rRNP) particles in the salivary glands of the dipteran Chironomus tentans. The passage of the RNPs through the nuclear pore complex (NPC) was inhibited with the nucleoporin-binding wheat germ agglutinin, and the effects were examined by electron microscopy. BR mRNPs bound to the nuclear basket increased in number, while BR mRNPs translocating through the central channel decreased, suggesting that the initiation of translocation proper had been inhibited. The rRNPs accumulated heavily in nucleoplasm, while no or very few rRNPs were recorded within nuclear baskets. Thus, the transport of rRNPs had been blocked prior to the entry into the baskets. Remarkably, the rRNPs had been excluded both from baskets and the space in between the baskets. We propose that normally basket fibrils move freely and repel RNPs from the exclusion zone unless the particles have affinity for and bind to nucleoporins within the baskets.

Photo induced multiple fragmentation of atoms and molecules: Dynamics of Coulombic many-particle systems studied with the COLTRIMS reaction microscope

International Nuclear Information System (INIS)

Czasch, A.; Schmidt, L.Ph.H.; Jahnke, T.; Weber, Th.; Jagutzki, O.; Schoessler, S.; Schoeffler, M.S.; Doerner, R.; Schmidt-Boecking, H.

2005-01-01

Many-particle dynamics in atomic and molecular physics has been investigated by using the COLTRIMS reaction microscope. The COLTRIMS technique visualizes photon and ion induced many-particle fragmentation processes in the eV and milli-eV regime. It reveals the complete momentum pattern in atomic and molecular many-particle reactions comparable to the bubble chamber in nuclear physics

Lidar- and balloon-borne particle counter comparisons following recent volcanic eruptions

Science.gov (United States)

Hofmann, D. J.; Rosen, J. M.; Reiter, R.; Jager, H.

1983-01-01

Balloon-borne particle counter measurements at Laramie, Wyoming (41 deg N) are used to calculate the expected lidar backscatter at 0.694 micron wavelength from July 1979 to February 1982, a period which included at least four detectable perturbations of the stratospheric aerosol layer due to volcanic eruptions. These calculations are compared with lidar measurements conducted at Garmisch-Partenkirchen (47.5 deg N) during the same period. While the agreement is generally good using only the main mode in the particle size distribution (radius about 0.07 micron) during approximately the first 6 months following a major volcanic eruption, a measured secondary mode near 1 micron radius, when included, improves the agreement. Calculations of the expected backscatter at 25-30 km reveal that substantial number of particles diffuse into this high altitude region about 7 months after a major eruption, and these particles should be taken into account when normalizing lidar at these altitudes.

Heating and generation of suprathermal particles at collisionless shocks

International Nuclear Information System (INIS)

Thomsen, M.F.

1985-01-01

Collisionless plasma shocks are different from ordinary collisional fluid shocks in several important respects. They do not in general heat the electrons and ions equally, nor do they produce Maxwellian velocity distributions downstream. Furthermore, they commonly generate suprathermal particles which propagate into the upstream region, giving advance warning of the presence of the shock and providing a ''seed'' population for further acceleration to high energies. Recent space observations and theory have revealed a great deal about the heating mechanisms which occur in collisionless shocks and about the origin of the various suprathermal particle populations which are found in association with them. An overview of the present understanding of these subjects is presented herein. 83 refs., 8 figs

Influence of Particle Size on Properties of Expanded Graphite

Directory of Open Access Journals (Sweden)

Kurajica, S

2010-02-01

between the graphene layers due to oxidation and repulsion of positively charged layers. The increased width and reduced height of diffraction peaks were a consequence of small-sized ordered domains. The intercalation is partial, intercalated layers are divided by a considerable number of non-intercalated layers. FTIR spectra revealed that dominant intercalating species is perchloric acid.Thermo-gravimetric analysis revealed that deintercalation occurs in the temperature interval between 150 and 300 °C and that a mass loss in this temperature interval is dependent on particle diameter, i. e. the intercalation is more intensive for greater particles. The fact that deintercalation proceeds as a one-stage process indicates the existence of only one intercalating specie. Additional mass loss at higher temperatures is a consequence of graphite oxidation.The particles with a higher amount of interlcalant showed greater expansion volumes as well as specific surface area. The fraction with greatest particle diameter (315–425 µm showed expansion specific volume of v=86 cm3g–1. Weaker expansion of smaller particles is a consequence of intercalant thermal degradation gaseous products loss at the layer edges, as well as of lesser amount of intercalants due to their removal during washing.Adsorption-desorption isotherms of expanded graphite could be classified as type III, according to BDDT/IUPAC classification, characteristic for macro porous materials. Small variations in adsorption and desorption pressure for the same amount of adsorbed gas indicate that the macro pores are open. Specific surface area was calculated using BET equation and for sample 315–425 yields s = 36 m2 g–1.SEM micrographs revealed typical worm-like microstructure generated by exfoliation of graphene sheets. The areas of intense exfoliation forming typical pores, as well as less exfoliated sheets canbe observed.

Quantum particle-number fluctuations in a two-component Bose gas in a double-well potential

International Nuclear Information System (INIS)

Zin, Pawel; Oles, Bartlomiej; Sacha, Krzysztof

2011-01-01

A two-component Bose gas in a double-well potential with repulsive interactions may undergo a phase separation transition if the interspecies interactions outweigh the intraspecies ones. We analyze the transition in the strong interaction limit within the two-mode approximation. Numbers of particles in each potential well are equal and constant. However, at the transition point, the ground state of the system reveals huge fluctuations of numbers of particles belonging to the different gas components; that is, the probability for observation of any mixture of particles in each potential well becomes uniform.

Streaming and particle motion in acoustically-actuated leaky systems

Science.gov (United States)

Nama, Nitesh; Barnkob, Rune; Jun Huang, Tony; Kahler, Christian; Costanzo, Francesco

2017-11-01

The integration of acoustics with microfluidics has shown great promise for applications within biology, chemistry, and medicine. A commonly employed system to achieve this integration consists of a fluid-filled, polymer-walled microchannel that is acoustically actuated via standing surface acoustic waves. However, despite significant experimental advancements, the precise physical understanding of such systems remains a work in progress. In this work, we investigate the nature of acoustic fields that are setup inside the microchannel as well as the fundamental driving mechanism governing the fluid and particle motion in these systems. We provide an experimental benchmark using state-of-art 3D measurements of fluid and particle motion and present a Lagrangian velocity based temporal multiscale numerical framework to explain the experimental observations. Following verification and validation, we employ our numerical model to reveal the presence of a pseudo-standing acoustic wave that drives the acoustic streaming and particle motion in these systems.

A model for particle acceleration in lower hybrid collapse

International Nuclear Information System (INIS)

Retterer, J.M.

1997-01-01

A model for particle acceleration during the nonlinear collapse of lower hybrid waves is described. Using the Musher-Sturman wave equation to describe the effects of nonlinear processes and a velocity diffusion equation for the particle velocity distribution, the model self-consistently describes the exchange of energy between the fields and the particles in the local plasma. Two-dimensional solutions are presented for the modulational instability of a plane wave and the collapse of a cylindrical wave packet. These calculations were motivated by sounding rocket observations in the vicinity of auroral arcs in the Earth close-quote s ionosphere, which have revealed the existence of large-amplitude lower-hybrid wave packets associated with ions accelerated to energies of 100 eV. The scaling of the sizes of these wave packets is consistent with the theory of lower-hybrid collapse and the observed lower-hybrid field amplitudes are adequate to accelerate the ionospheric ions to the observed energies

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.

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

Surface modification and particles size distribution control in nano-CdS/polystyrene composite film

International Nuclear Information System (INIS)

Min Zhirong; Ming Qiuzhang; Hai Chunliang; Han Minzeng

2003-01-01

Preparation of nano-CdS particles with surface thiol modification by microemulsion method and their influences on the particle size distribution in highly filled polystyrene-based composites were studied. The modified nano-CdS was characterized by X-ray photoelectron spectroscopy (XPS), light absorption and emission measurements to reveal the morphologies of the surface modifier, which are consistent with the surface molecules packing calculation. The morphologies of the surface modifier exerted a great influence not only on the optical performance of the particles themselves, but also on the size distribution of the particle in polystyrene matrix. A monolayer coverage with tightly packed thiol molecules was believed to be most effective in promoting a uniform particle size distribution and eliminating the surface defects that cause radiationless recombination. Control of the particles size distribution in polystyrene can be attained by adjusting surface coverage status of the thiol molecules based on the strong interaction between the surface modifier and the matrix

The impact of aerosol composition on the particle to gas partitioning of reactive mercury.

Science.gov (United States)

Rutter, Andrew P; Schauer, James J

2007-06-01

A laboratory system was developed to study the gas-particle partitioning of reactive mercury (RM) as a function of aerosol composition in synthetic atmospheric particulate matter. The collection of RM was achieved by filter- and sorbent-based methods. Analyses of the RM collected on the filters and sorbents were performed using thermal extraction combined with cold vapor atomic fluorescence spectroscopy (CVAFS), allowing direct measurement of the RM load on the substrates. Laboratory measurements of the gas-particle partitioning coefficients of RM to atmospheric aerosol particles revealed a strong dependence on aerosol composition, with partitioning coefficients that varied by orders of magnitude depending on the composition of the particles. Particles of sodium nitrate and the chlorides of potassium and sodium had high partitioning coefficients, shifting the RM partitioning toward the particle phase, while ammonium sulfate, levoglucosan, and adipic acid caused the RM to partition toward the gas phase and, therefore, had partitioning coefficients that were lower by orders of magnitude.

Formation and alteration of airborne particles in the subway environment.

Science.gov (United States)

Moreno, T; Querol, X; Martins, V; Minguillón, M C; Reche, C; Ku, L H; Eun, H R; Ahn, K H; Capdevila, M; de Miguel, E

2017-01-25

Most particles in the rail subway environment are sub-micron sized ferruginous flakes and splinters generated mechanically by frictional wear of brake pads, wheels and rails. To better understand the mechanisms of formation and the alteration processes affecting inhalable particles in subways, PM samples (1-2.5 μm and 2.5-10 μm) were collected in the Barcelona Metro and then studied under a scanning electron microscope. Most particles in these samples are hematitic (up to 88%), with relatively minor amounts of mineral matter (up to 9%) and sulphates (up to 5%). Detailed microscopy (using back scattered and TEM-DRX imaging) reveals how many of the metallic particles comprise the metallic Fe nucleus surrounded by hematite (Fe 2 O 3 ) and a coating of sulphate and chloride salts mixed with mineral matter (including Ca-carbonates, clay minerals and quartz). These observations record the emission of fine to ultrafine FePM by frictional wear at elevated temperatures that promote rapid partial (or complete) oxidation of the native metal. Water condensing on the PM surface during cooling leads to the adsorption of inorganic mineral particles that coat the iron oxide. The distinctively layered polymineralic structure that results from these processes is peculiar to particles generated in the subway environment and very different from PM typically inhaled outdoors.

Study of talcum charging status in parallel plate electrostatic separator based on particle trajectory analysis

Science.gov (United States)

Yunxiao, CAO; Zhiqiang, WANG; Jinjun, WANG; Guofeng, LI

2018-05-01

Electrostatic separation has been extensively used in mineral processing, and has the potential to separate gangue minerals from raw talcum ore. As for electrostatic separation, the particle charging status is one of important influence factors. To describe the talcum particle charging status in a parallel plate electrostatic separator accurately, this paper proposes a modern images processing method. Based on the actual trajectories obtained from sequence images of particle movement and the analysis of physical forces applied on a charged particle, a numerical model is built, which could calculate the charge-to-mass ratios represented as the charging status of particle and simulate the particle trajectories. The simulated trajectories agree well with the experimental results obtained by images processing. In addition, chemical composition analysis is employed to reveal the relationship between ferrum gangue mineral content and charge-to-mass ratios. Research results show that the proposed method is effective for describing the particle charging status in electrostatic separation.

Numerical Simulation and Experimental Investigation of Multi-function Micro-plasma Jet and Alumina Particle Behaviour

Directory of Open Access Journals (Sweden)

Liu Gu

2016-01-01

Full Text Available Turbulent flow in multi-function micro-plasma spray, as well as the trajectories and state-changing course of alumina particles in the plasma jet were simulated. The distribution of temperature and velocity of the plasma jet and in-flight alumina particles is discussed. Calculations show that particles are heated and accelerated sufficiently by the plasma flame due to a longer travel time than that of external injection system, therefore, possess higher temperature and velocity. Alumina particles temperature and velocity increase rapidly along the jet axis at the initial stage, but then decrease gradually. The velocity and surface temperature of in-flight alumina particles are measured by Spray Watch-2i system. The velocity and surface temperature of alumina particles measured agree well with the simulation results, confirming that the simulation model is suitable for the prediction of the turbulent flow and the particle characteristics, which also reveals the superiority of the plasma spray gun in this multi-function micro-plasma spraying system.

Electrostatic Charging and Particle Interactions in Microscopic Insulating Grains

Science.gov (United States)

Lee, Victor

In this thesis, we experimentally investigate the electrostatic charging as well as the particle interactions in microscopic insulating grains. First, by tracking individual grains accelerated in an electric field, we quantitatively demonstrate that tribocharging of same-material grains depends on particle size. Large grains tend to charge positively, and small ones tend to charge negatively. Theories based on the transfer of trapped electrons can explain this tendency but have not been validated. Here we show that the number of trapped electrons, measured independently by a thermoluminescence technique, is orders of magnitude too small to be responsible for the amount of charge transferred. This result reveals that trapped electrons are not responsible for same-material tribocharging of dielectric particles. Second, same-material tribocharging in grains can result in important long-range electrostatic interactions. However, how these electrostatic interactions contribute to particle clustering remains elusive, primarily due to the lack of direct, detailed observations. Using a high-speed camera that falls with a stream charged grains, we observe for the first time how charged grains can undergo attractive as well as repulsive Kepler-like orbits. Charged particles can be captured in their mutual electrostatic potential and form clusters via multiple bounces. Dielectric polarization effects are directly observed, which lead to additional attractive forces and stabilize "molecule-like" arrangements of charged particles. Third, we have developed a new method to study the charge transfer of microscopic particles based on acoustic levitation techniques. This method allows us to narrow the complex problem of many-particle charging down to precise charge measurements of a single sub-millimeter particle colliding with a target plate. By simply attaching nonpolar groups onto glass surfaces, we show that the contact charging of a particle is highly dependent on

Characterization of saturation of CR-39 detector at high alpha-particle fluence

Directory of Open Access Journals (Sweden)

M. El Ghazaly

2018-04-01

Full Text Available The occurrence of saturation in the CR-39 detector reduces and limits its detection dynamic range; nevertheless, this range could be extended using spectroscopic techniques and by measuring the net bulk rate of the saturated CR-39 detector surface. CR-39 detectors were irradiated by 1.5 MeV high alpha-particle fluence varying from 0.06 × 108 to 7.36 × 108 alphas/cm2 from Am-241 source; thereafter, they were etched in a 6.25N NaOH solution at a temperature of 70°C for different durations. Net bulk etch rate measurement of the 1.5 MeV alpha-irradiated CR-39 detector surface revealed that rate increases with increasing etching time and reaches its maximum value at the end of the alpha-particle range. It is also correlated with the alpha-particle fluence. The measurements of UV–Visible (UV–Vis absorbance at 500 and 600 nm reveal that the absorbance is linearly correlated with the fluence of alpha particles at the etching times of 2 and 4 hour. For extended etching times of 6, 10, and 14.5 hour, the absorbance is saturated for fluence values of 4.05 × 108, 5.30 × 108, and 7.36 × 108 alphas/cm2. These new methods pave the way to extend the dynamic range of polymer-based solid state nuclear track detectors (SSNTDs in measurement of high fluence of heavy ions as well as in radiation dosimetry. Keywords: Alpha Particle, Bulk Etch Rate, CR-39 Detector, Saturated Regime, UV–Vis Spectroscopy

Observations of Solar Energetic Particle Anisotropies at MeV Energies from STEREO/LET

Science.gov (United States)

Leske, R. A.; Cummings, A. C.; Cohen, C.; Mewaldt, R. A.; Labrador, A. W.; Stone, E. C.; Wiedenbeck, M. E.; Christian, E. R.; von Rosenvinge, T. T.

2016-12-01

During the transport of solar energetic particles (SEPs) through interplanetary space, their pitch-angle distributions are modified by the competing effects of scattering and magnetic focusing. Thus, measurements of SEP anisotropies can reveal conditions such as magnetic field strength, topology, and turbulence levels at heliospheric locations far removed from the observer. Onboard each of the two STEREO spacecraft, the Low Energy Telescope (LET) measures angular distributions in the ecliptic for SEP protons, helium, and heavier ions up to iron with energies of about 2-12 MeV/nucleon. Anisotropies observed with this instrument include unidirectional outward beams at the onset of magnetically well-connected SEP events when particles experienced little scattering, bidirectional flows within many interplanetary coronal mass ejections, sunward particle flows when the spacecraft was magnetically connected to the back side of a shock, and loss-cone distributions when particles with large pitch angles were magnetically mirrored at a remote field enhancement that was too weak to reflect particles with the smallest pitch angles. Observations at a 1-minute cadence also revealed peculiar oscillations in the width of a beamed distribution at the onset of the 23 July 2012 extreme SEP event. The shapes of the pitch angle distributions often vary with energy and differ for H, He, and heavier species, perhaps as a result of rigidity dependence of the pitch angle diffusion coefficient. We present a selection of the more interesting LET anisotropy observations made throughout solar cycle 24 and discuss the implications of these observations for SEP transport in the heliosphere.

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.

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.

Induced fission track distribution from highly radioactive particles in fallout materials

International Nuclear Information System (INIS)

Hashimoto, Tetsuo; Okada, Tatemichi

1987-01-01

Some highly radioactive fallout particles (GPs) from the 19th Chinese nuclear detonation were followed to the neutron irradiation in a reactor after sandwiched with mica detectors. The interesting star-like fission track patterns were revealed on the etched surface of the mica detectors. The simple chemical separation procedure for the GPs was applied for the separation of U and Pu as fissile elements and the both resultant fractions were examined with the similar high sensitive fission tracking detection. Subsequently, a representative track pattern from a black spherical particle was subjected to the determination of fissile nuclide content; comparing the total fission events evaluated on the basis of the numerical calculation of track densities with the total thermal neutron fluence. The results implied that the uranium is responsible for the main fissile nuclide remaining within a particle as unfissioned fractions and should be certainly enriched with respect to U-235 within such small fallout particles. This sophisticated method was also applied to determine the dead GPs, which have been highly radioactive particles just after the detonations, in the rain and snow-residual materials. Many induced star-like fission tracks verified certainly that there remains a lot of dead particles in the atmosheric environment till nowadays. (author)

Single-particle characterization of the high-Arctic summertime aerosol

Directory of Open Access Journals (Sweden)

B. Sierau

2014-07-01

Full Text Available Single-particle mass-spectrometric measurements were carried out in the high Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS. The instrument deployed was an aerosol time-of-flight mass spectrometer (ATOFMS that provides information on the chemical composition of individual particles and their mixing state in real time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 and 3000 nm in diameter showed mass-spectrometric patterns, indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the high Arctic. To assess the importance of long-range particle sources for aerosol–cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest the presence of a particle type of

Single-particle characterization of the high-Arctic summertime aerosol

Science.gov (United States)

Sierau, B.; Chang, R. Y.-W.; Leck, C.; Paatero, J.; Lohmann, U.

2014-07-01

Single-particle mass-spectrometric measurements were carried out in the high Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS). The instrument deployed was an aerosol time-of-flight mass spectrometer (ATOFMS) that provides information on the chemical composition of individual particles and their mixing state in real time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 and 3000 nm in diameter showed mass-spectrometric patterns, indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the high Arctic. To assess the importance of long-range particle sources for aerosol-cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest the presence of a particle type of unknown composition

Single-particle characterization of the High Arctic summertime aerosol

Science.gov (United States)

Sierau, B.; Chang, R. Y.-W.; Leck, C.; Paatero, J.; Lohmann, U.

2014-01-01

Single-particle mass spectrometric measurements were carried out in the High Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS). The instrument deployed was an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) that provides information on the chemical composition of individual particles and their mixing state in real-time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 nm to 3000 nm in diameter showed mass spectrometric patterns indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the High Arctic. To assess the importance of long-range particle sources for aerosol-cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a~minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest a presence of a particle type of unknown composition

Particle therapy

Energy Technology Data Exchange (ETDEWEB)

Raju, M.R.

1993-09-01

Particle therapy has a long history. The experimentation with particles for their therapeutic application got started soon after they were produced in the laboratory. Physicists played a major role in proposing the potential applications in radiotherapy as well as in the development of particle therapy. A brief review of the current status of particle radiotherapy with some historical perspective is presented and specific contributions made by physicists will be pointed out wherever appropriate. The rationale of using particles in cancer treatment is to reduce the treatment volume to the target volume by using precise dose distributions in three dimensions by using particles such as protons and to improve the differential effects on tumors compared to normal tissues by using high-LET radiations such as neutrons. Pions and heavy ions combine the above two characteristics.

Particle therapy

International Nuclear Information System (INIS)

Raju, M.R.

1993-01-01

Particle therapy has a long history. The experimentation with particles for their therapeutic application got started soon after they were produced in the laboratory. Physicists played a major role in proposing the potential applications in radiotherapy as well as in the development of particle therapy. A brief review of the current status of particle radiotherapy with some historical perspective is presented and specific contributions made by physicists will be pointed out wherever appropriate. The rationale of using particles in cancer treatment is to reduce the treatment volume to the target volume by using precise dose distributions in three dimensions by using particles such as protons and to improve the differential effects on tumors compared to normal tissues by using high-LET radiations such as neutrons. Pions and heavy ions combine the above two characteristics

New insights in particle dynamics from group cohomology

International Nuclear Information System (INIS)

Aldaya, V; Jaramillo, J L; Guerrero, J

2002-01-01

The dynamics of a particle moving in background electromagnetic and gravitational fields is revisited from a Lie group cohomological perspective. Physical constants characterizing the particle appear as central extension parameters of a group which is obtained from a centrally extended kinematical group (Poincare or Galilei) by making some subgroup local. The corresponding dynamics is generated by a vector field inside the kernel of a pre-symplectic form which is derived from the canonical left-invariant 1-form on the extended group. A non-relativistic limit is derived from the geodesic motion via an Inoenue-Wigner contraction. A deeper analysis of the cohomological structure reveals the possibility of a new force associated with a non-trivial mixing of gravity and electromagnetism leading to, in principle, testable predictions. (letter to the editor)

APM_GUI: analyzing particle movement on the cell membrane and determining confinement.

Science.gov (United States)

Menchón, Silvia A; Martín, Mauricio G; Dotti, Carlos G

2012-02-20

Single-particle tracking is a powerful tool for tracking individual particles with high precision. It provides useful information that allows the study of diffusion properties as well as the dynamics of movement. Changes in particle movement behavior, such as transitions between Brownian motion and temporary confinement, can reveal interesting biophysical interactions. Although useful applications exist to determine the paths of individual particles, only a few software implementations are available to analyze these data, and these implementations are generally not user-friendly and do not have a graphical interface,. Here, we present APM_GUI (Analyzing Particle Movement), which is a MatLab-implemented application with a Graphical User Interface. This user-friendly application detects confined movement considering non-random confinement when a particle remains in a region longer than a Brownian diffusant would remain. In addition, APM_GUI exports the results, which allows users to analyze this information using software that they are familiar with. APM_GUI provides an open-source tool that quantifies diffusion coefficients and determines whether trajectories have non-random confinements. It also offers a simple and user-friendly tool that can be used by individuals without programming skills.

APM_GUI: analyzing particle movement on the cell membrane and determining confinement

Directory of Open Access Journals (Sweden)

Menchón Silvia A

2012-02-01

Full Text Available Abstract Background Single-particle tracking is a powerful tool for tracking individual particles with high precision. It provides useful information that allows the study of diffusion properties as well as the dynamics of movement. Changes in particle movement behavior, such as transitions between Brownian motion and temporary confinement, can reveal interesting biophysical interactions. Although useful applications exist to determine the paths of individual particles, only a few software implementations are available to analyze these data, and these implementations are generally not user-friendly and do not have a graphical interface,. Results Here, we present APM_GUI (Analyzing Particle Movement, which is a MatLab-implemented application with a Graphical User Interface. This user-friendly application detects confined movement considering non-random confinement when a particle remains in a region longer than a Brownian diffusant would remain. In addition, APM_GUI exports the results, which allows users to analyze this information using software that they are familiar with. Conclusions APM_GUI provides an open-source tool that quantifies diffusion coefficients and determines whether trajectories have non-random confinements. It also offers a simple and user-friendly tool that can be used by individuals without programming skills.

Particle Emissions from Biomass Combustion

Energy Technology Data Exchange (ETDEWEB)

Szpila, Aneta; Bohgard, Mats [Lund Inst. of Technology (Sweden). Div. of Ergonomics and Aerosol Technology; Strand, Michael; Lillieblad, Lena; Sanati, Mehri [Vaexjoe Univ. (Sweden). Div. of Bioenergy Technology; Pagels, Joakim; Rissler, Jenny; Swietlicki, Erik; Gharibi, Arash [Lund Univ. (Sweden). Div. of Nuclear Physics

2003-05-01

particle number concentration increased slightly with increasing load, at the same time the fine mode particles became smaller. This was probably caused by different degree of particle coagulation as the residence time in the boiler was changed. The mean diameter during combustion of forest residue was around 100 nm compared to 70-80 nm for dry wood and pellets, while the total number was close to constant. This explains the differences in mass concentration found in the impactor measurements. The concentrations of CO and THC was highest for the dry wood fuel, the PAH concentration was highest for pellets combustion in boiler 4, however this boiler was poorly tuned at the time of measurement. The PAH concentration was 5 times higher during combustion of dry wood compared to forest residue. The concentration of CO, THC and PAH varied to a great extend. The high concentrations were measured in boilers running at a low load. The concentration of particle organic carbon was less than 15% of PMI for all fuels. However we used heated primary dilution, which inhibits the condensation of organic components into, the particle phase. A significant fraction of the emitted organic carbon may condense to the particle phase during dilution after the stack or after being oxidized in the atmosphere. We also measured elemental carbon in the particle phase. The contribution to PM1 was as high as 25-30% during pellets combustion at low load and 8% at low load during combustion of dry wood. In all other cases the EC-concentration was less than 3% of PMI. PIXE and lon-chromatography confirmed that alkali-salts were the dominant chemical species. PIXE analysis revealed that emitted amounts of heavy metals such as Zn, Cd and Pb are strongly dependent on the type of the fuel used. Forest residues gave high emissions of Zn, Cd and Pb, while pellets gave very high emissions of Cd and Zn. The fuel with the lowest emissions of heavy metals was dry wood. This again could be related to ash content in

Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques

Science.gov (United States)

Worringen, A.; Kandler, K.; Benker, N.; Dirsch, T.; Mertes, S.; Schenk, L.; Kästner, U.; Frank, F.; Nillius, B.; Bundke, U.; Rose, D.; Curtius, J.; Kupiszewski, P.; Weingartner, E.; Vochezer, P.; Schneider, J.; Schmidt, S.; Weinbruch, S.; Ebert, M.

2015-04-01

In the present work, three different techniques to separate ice-nucleating particles (INPs) as well as ice particle residuals (IPRs) from non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed-phase clouds and allow after evaporation in the instrument for the analysis of the residuals. The Fast Ice Nucleus Chamber (FINCH) coupled with the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated particles for analysis. The instruments were run during a joint field campaign which took place in January and February 2013 at the High Alpine Research Station Jungfraujoch (Switzerland). INPs and IPRs were analyzed offline by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Online analysis of the size and chemical composition of INP activated in FINCH was performed by laser ablation mass spectrometry. With all three INP/IPR separation techniques high abundances (median 20-70%) of instrumental contamination artifacts were observed (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). After removal of the instrumental contamination particles, silicates, Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types obtained by all three techniques. In addition, considerable amounts (median abundance mostly a few percent) of soluble material (e.g., sea salt, sulfates) were observed. As these soluble particles are often not expected to act as INP/IPR, we consider them as potential measurement artifacts. Minor types of INP/IPR include soot and Pb-bearing particles. The Pb-bearing particles are mainly present as an internal mixture with other particle types. Most samples showed a maximum of the INP/IPR size distribution at 200

Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers

Energy Technology Data Exchange (ETDEWEB)

Abbas, M., E-mail: micheline.abbas@ensiacet.fr [Laboratoire de Génie Chimique, Université de Toulouse INPT-UPS, 31030, Toulouse (France); CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Magaud, P. [CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Institut Clément Ader, Université de Toulouse UPS-INSA-ISAE-Mines Albi, 31400, Toulouse (France); Gao, Y. [Institut Clément Ader, Université de Toulouse UPS-INSA-ISAE-Mines Albi, 31400, Toulouse (France); Geoffroy, S. [CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Laboratoire Matériaux et Durabilité des Constructions, Université de Toulouse (France); UPS, INSA, 31077, Toulouse (France)

2014-12-15

The migration of neutrally buoyant finite sized particles in a Newtonian square channel flow is investigated in the limit of very low solid volumetric concentration, within a wide range of channel Reynolds numbers Re = [0.07-120]. In situ microscope measurements of particle distributions, taken far from the channel inlet (at a distance several thousand times the channel height), revealed that particles are preferentially located near the channel walls at Re > 10 and near the channel center at Re < 1. Whereas the cross-streamline particle motion is governed by inertia-induced lift forces at high inertia, it seems to be controlled by shear-induced particle interactions at low (but finite) Reynolds numbers, despite the low solid volume fraction (<1%). The transition between both regimes is observed in the range Re = [1-10]. In order to exclude the effect of multi-body interactions, the trajectories of single freely moving particles are calculated thanks to numerical simulations based on the force coupling method. With the deployed numerical tool, the complete particle trajectories are accessible within a reasonable computational time only in the inertial regime (Re > 10). In this regime, we show that (i) the particle undergoes cross-streamline migration followed by a cross-lateral migration (parallel to the wall) in agreement with previous observations, and (ii) the stable equilibrium positions are located at the midline of the channel faces while the diagonal equilibrium positions are unstable. At low flow inertia, the first instants of the numerical simulations (carried at Re = O(1)) reveal that the cross-streamline migration of a single particle is oriented towards the channel wall, suggesting that the particle preferential positions around the channel center, observed in the experiments, are rather due to multi-body interactions.

Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers

International Nuclear Information System (INIS)

Abbas, M.; Magaud, P.; Gao, Y.; Geoffroy, S.

2014-01-01

The migration of neutrally buoyant finite sized particles in a Newtonian square channel flow is investigated in the limit of very low solid volumetric concentration, within a wide range of channel Reynolds numbers Re = [0.07-120]. In situ microscope measurements of particle distributions, taken far from the channel inlet (at a distance several thousand times the channel height), revealed that particles are preferentially located near the channel walls at Re > 10 and near the channel center at Re < 1. Whereas the cross-streamline particle motion is governed by inertia-induced lift forces at high inertia, it seems to be controlled by shear-induced particle interactions at low (but finite) Reynolds numbers, despite the low solid volume fraction (<1%). The transition between both regimes is observed in the range Re = [1-10]. In order to exclude the effect of multi-body interactions, the trajectories of single freely moving particles are calculated thanks to numerical simulations based on the force coupling method. With the deployed numerical tool, the complete particle trajectories are accessible within a reasonable computational time only in the inertial regime (Re > 10). In this regime, we show that (i) the particle undergoes cross-streamline migration followed by a cross-lateral migration (parallel to the wall) in agreement with previous observations, and (ii) the stable equilibrium positions are located at the midline of the channel faces while the diagonal equilibrium positions are unstable. At low flow inertia, the first instants of the numerical simulations (carried at Re = O(1)) reveal that the cross-streamline migration of a single particle is oriented towards the channel wall, suggesting that the particle preferential positions around the channel center, observed in the experiments, are rather due to multi-body interactions

Cellular Antiviral Factors that Target Particle Infectivity of HIV-1.

Science.gov (United States)

Goffinet, Christine

2016-01-01

In the past decade, the identification and characterization of antiviral genes with the ability to interfere with virus replication has established cell-intrinsic innate immunity as a third line of antiviral defense in addition to adaptive and classical innate immunity. Understanding how cellular factors have evolved to inhibit HIV-1 reveals particularly vulnerable points of the viral replication cycle. Many, but not all, antiviral proteins share type I interferon-upregulated expression and sensitivity to viral counteraction or evasion measures. Whereas well-established restriction factors interfere with early post-entry steps and release of HIV-1, recent research has revealed a diverse set of proteins that reduce the infectious quality of released particles using individual, to date poorly understood modes of action. These include induction of paucity of mature glycoproteins in nascent virions or self-incorporation into the virus particle, resulting in poor infectiousness of the virion and impaired spread of the infection. A better understanding of these newly discovered antiviral factors may open new avenues towards the design of drugs that repress the spread of viruses whose genomes have already integrated.

Influence of maize flour particle size on gluten-free breadmaking.

Science.gov (United States)

de la Hera, Esther; Talegón, María; Caballero, Pedro; Gómez, Manuel

2013-03-15

Maize, one of the suitable grains for coeliac consumption, is, together with rice, the most cultivated cereal in the world. However, the inclusion of maize flour in gluten-free bread is a minority and studies are scarce. This paper analyses the influence of different maize flour types and their particle sizes on the quality of two types of bread without gluten (80% and 110% water in the formulation) obtained from them. We also analysed the microstructure of the dough and its behaviour during the fermentation. Finer flours had a lower dough development during fermentation in all cases. Among the different types of flour, those whose microstructure revealed compact particles were those which had higher specific bread volume, especially when the particle size was greater. Among the formulations, the dough with more water gave breads with higher specific volume, an effect that was more important in more compact flours. The higher volume breads had lower values of hardness and resilience. The type of corn flour and mainly its particle size influence significantly the dough development of gluten-free bread during fermentation and therefore the final volume and texture of the breads obtained. The flours having coarser particle size are the most suitable for making gluten-free maize bread. © 2012 Society of Chemical Industry.

Hierarchical Ag mesostructures for single particle SERS substrate

Energy Technology Data Exchange (ETDEWEB)

Xu, Minwei, E-mail: xuminwei@xjtu.edu.cn; Zhang, Yin

2017-01-30

Highlights: • Hierarchical Ag mesostructures with the size of 250, 360 and 500 nm are synthesized via a seed-mediated approach. • The Ag mesostructures present the tailorable size and highly roughened surfaces. • The average enhancement factors for individual Ag mesostructures were estimated to be as high as 10{sup 6}. - Abstract: Hierarchical Ag mesostructures with highly rough surface morphology have been synthesized at room temperature through a simple seed-mediated approach. Electron microscopy characterizations indicate that the obtained Ag mesostructures exhibit a textured surface morphology with the flower-like architecture. Moreover, the particle size can be tailored easily in the range of 250–500 nm. For the growth process of the hierarchical Ag mesostructures, it is believed that the self-assembly mechanism is more reasonable rather than the epitaxial overgrowth of Ag seed. The oriented attachment of nanoparticles is revealed during the formation of Ag mesostructures. Single particle surface enhanced Raman spectra (sp-SERS) of crystal violet adsorbed on the hierarchical Ag mesostructures were measured. Results reveal that the hierarchical Ag mesostructures can be highly sensitive sp-SERS substrates with good reproducibility. The average enhancement factors for individual Ag mesostructures are estimated to be about 10{sup 6}.

Fireworks induced particle pollution: A spatio-temporal analysis

Science.gov (United States)

Kumar, M.; Singh, R. K.; Murari, V.; Singh, A. K.; Singh, R. S.; Banerjee, T.

2016-11-01

Diwali-specific firework induced particle pollution was measured in terms of aerosol mass loading, type, optical properties and vertical distribution. Entire nation exhibited an increase in particulate concentrations specifically in Indo-Gangetic Plain (IGP). Aerosol surface mass loading at middle IGP revealed an increase of 56-121% during festival days in comparison to their background concentrations. Space-borne measurements (Aqua and Terra-MODIS) typically identified IGP with moderate to high AOD (0.3-0.8) during pre-festive days which transmutes to very high AOD (0.4-1.8) during Diwali-day with accumulation of aerosol fine mode fractions (0.3-1.0). Most of the aerosol surface monitoring stations exhibited increase in PM2.5 especially on Diwali-day while PM10 exhibited increase on subsequent days. Elemental compositions strongly support K, Ba, Sr, Cd, S and P to be considered as firework tracers. The upper and middle IGP revealed dominance of absorbing aerosols (OMI-AI: 0.80-1.40) while CALIPSO altitude-orbit-cross-section profiles established the presence of polluted dust which eventually modified with association of smoke and polluted continental during extreme fireworks. Diwali-specific these observations have implications on associating fireworks induced particle pollution and human health while inclusion of these observations should improve regional air quality model.

Particle physics

International Nuclear Information System (INIS)

Kamal, Anwar

2014-01-01

Provides step-by-step derivations. Contains numerous tables and diagrams. Supports learning and teaching with numerous worked examples, questions and problems with answers. Sketches also the historical development of the subject. This textbook teaches particle physics very didactically. It supports learning and teaching with numerous worked examples, questions and problems with answers. Numerous tables and diagrams lead to a better understanding of the explanations. The content of the book covers all important topics of particle physics: Elementary particles are classified from the point of view of the four fundamental interactions. The nomenclature used in particle physics is explained. The discoveries and properties of known elementary particles and resonances are given. The particles considered are positrons, muon, pions, anti-protons, strange particles, neutrino and hadrons. The conservation laws governing the interactions of elementary particles are given. The concepts of parity, spin, charge conjugation, time reversal and gauge invariance are explained. The quark theory is introduced to explain the hadron structure and strong interactions. The solar neutrino problem is considered. Weak interactions are classified into various types, and the selection rules are stated. Non-conservation of parity and the universality of the weak interactions are discussed. Neutral and charged currents, discovery of W and Z bosons and the early universe form important topics of the electroweak interactions. The principles of high energy accelerators including colliders are elaborately explained. Additionally, in the book detectors used in nuclear and particle physics are described. This book is on the upper undergraduate level.

Synthesis, structural and magnetic characterization of soft magnetic nanocrystalline ternary FeNiCo particles

Energy Technology Data Exchange (ETDEWEB)

Toparli, Cigdem [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf (Germany); Ebin, Burçak [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Nuclear Chemistry and Industrial Material Recycling, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, S-412 96 Gothenburg (Sweden); Gürmen, Sebahattin, E-mail: gurmen@itu.edu.tr [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey)

2017-02-01

The present study focuses on the synthesis, microstructural and magnetic properties of ternary FeNiCo nanoparticles. Nanocrystalline ternary FeNiCo particles were synthesized via hydrogen reduction assisted ultrasonic spray pyrolysis method in single step. The effect of precursor concentration on the morphology and the size of particles was investigated. The syntheses were performed at 800 °C. Structure, morphology and magnetic properties of the as-prepared products were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) studies. Scherer calculation revealed that crystallite size of the ternary particles ranged between 36 and 60 nm. SEM and TEM investigations showed that the particle size was strongly influenced by the precursor concentration and Fe, Ni, Co elemental composition of individual particles was homogeneous. Finally, the soft magnetic properties of the particles were observed to be a function of their size. - Highlights: • Ternary FeNiCo alloy nanocrystalline particles were synthesized in a single step. • Cubic crystalline structure and spherical morphology was observed by XRD, SEM and TEM investigations. • The analysis of magnetic properties indicates the soft magnetic features of particles.

3D Lagrangian Model of Particle Saltation in an Open Channel Flow with Emphasis on Particle-Particle Collisions

Science.gov (United States)

Moreno, P. A.; Bombardelli, F. A.

2012-12-01

Particles laying motionless at the bed of rivers, lakes and estuaries can be put into motion when the shear stress exerted by the flow on the particles exceeds the critical shear stress. When these particles start their motion they can either remain suspended by long periods of time (suspended load) or move close to the bed (bed load). Particles are transported as bed load in three different modes: Sliding, rolling and saltation. Saltation is usually described as the bouncing motion of sediment particles in a layer a few particle diameters thick. The amount of particles and the bed-load mode in which they move depend on the particle size and density, and the flow intensity, usually quantified by the shear velocity. The bottom shear stress in natural streams will most likely be large enough to set saltation as the most important bed-load transport mechanism among all three modes. Thus, studying the saltation process is crucial for the overall understanding of bed-load transport. Particularly, numerical simulations of this process have been providing important insight regarding the relative importance of the physical mechanisms involved in it. Several processes occur when particles are saltating near the bed: i) Particles collide with the bed, ii) they "fly" between collisions with the bed, as a result of their interaction with the fluid flow, iii) and they collide among themselves. These processes can be simulated using a three-dimensional Eulerian-Lagrangian model. In order to mimic these processes we have experimented with an averaged turbulent flow field represented by the logarithmic law of the wall, and with a more involved approach in which a computed turbulent velocity field for a flat plate was used as a surrogate of the three-dimensional turbulent conditions present close to stream beds. Since flat-plate and open-channel boundary layers are essentially different, a dynamic similarity analysis was performed showing that the highly-resolved three

Detection of alpha particles and Cf-252 fission fragments with solid track detectors and surface barrier detector. Efficiency calculation

International Nuclear Information System (INIS)

Khouri, M.T.F.C.; Koskinas, M.F.; Andrade, C. de; Vilela, E.C.; Hinostroza, H.; Kaschiny, J.E.A.; Costa, M.S. da; Rizzo, P.; Santos, W.M.S.

1990-01-01

A technique for particle detection by using track solid detector and also types of revealing and result analysis are presented concerned to Cf-252 fission fragments detection. Measurements of alpha particles detection efficiency using Makrofol E and surface barrier detector are performed. (L.C.J.A.)

Nano-socketed nickel particles with enhanced coking resistance grown in situ by redox exsolution

Science.gov (United States)

Neagu, Dragos; Oh, Tae-Sik; Miller, David N.; Ménard, Hervé; Bukhari, Syed M.; Gamble, Stephen R.; Gorte, Raymond J.; Vohs, John M.; Irvine, John T. S.

2015-09-01

Metal particles supported on oxide surfaces are used as catalysts for a wide variety of processes in the chemical and energy conversion industries. For catalytic applications, metal particles are generally formed on an oxide support by physical or chemical deposition, or less commonly by exsolution from it. Although fundamentally different, both methods might be assumed to produce morphologically and functionally similar particles. Here we show that unlike nickel particles deposited on perovskite oxides, exsolved analogues are socketed into the parent perovskite, leading to enhanced stability and a significant decrease in the propensity for hydrocarbon coking, indicative of a stronger metal-oxide interface. In addition, we reveal key surface effects and defect interactions critical for future design of exsolution-based perovskite materials for catalytic and other functionalities. This study provides a new dimension for tailoring particle-substrate interactions in the context of increasing interest for emergent interfacial phenomena.

Simultaneous measurement of particle and fluid velocities in particle-laden flows

International Nuclear Information System (INIS)

Jin, D. X.; Lee, D. Y.

2009-01-01

For the velocity measurement in a particle-laden fluid flow, the fluid velocity and the inherently dispersed particle velocity can be analyzed by using PIV and PTV, respectively. Since the PIV result statistically represents the average displacement of all the particles in a PIV image, it is inevitable that the PIV result includes the influence of the dispersed particles' displacement if a single CCD camera is used to simultaneously measure the fluid velocity and the dispersed particle velocity. The influence of dispersed particles should be excluded before the PIV analysis in order to evaluate the fluid velocity accurately. In this study, the optimum replacement brightness of dispersed particles to minimize the false influence of dispersed particles on the PIV analysis was theoretically derived. Simulation results show that the modification of dispersed particle brightness can significantly reduce the PIV error caused by the dispersed particles. This modification method was also verified in the analysis of an actual experimental case of the particle-laden fluid flow in a triangular grooved channel

Aging induced changes on NEXAFS fingerprints in individual combustion particles

Directory of Open Access Journals (Sweden)

V. Zelenay

2011-11-01

Full Text Available Soot particles can significantly influence the Earth's climate by absorbing and scattering solar radiation as well as by acting as cloud condensation nuclei. However, despite their environmental (as well as economic and political importance, the way these properties are affected by atmospheric processing of the combustion exhaust gases is still a subject of discussion. In this work, individual soot particles emitted from two different vehicles, a EURO 2 transporter, a EURO 3 passenger car, and a wood stove were investigated on a single-particle basis. The emitted exhaust, including the particulate and the gas phase, was processed in a smog chamber with artificial solar radiation. Single particle specimens of both unprocessed and aged soot were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS and scanning electron microscopy. Comparison of NEXAFS spectra from the unprocessed particles and those resulting from exhaust photooxidation in the chamber revealed changes in the carbon functional group content. For the wood stove emissions, these changes were minor, related to the relatively mild oxidation conditions. For the EURO 2 transporter emissions, the most apparent change was that of carboxylic carbon from oxidized organic compounds condensing on the primary soot particles. For the EURO 3 car emissions oxidation of primary soot particles upon photochemical aging has likely contributed as well. Overall, the changes in the NEXAFS fingerprints were in qualitative agreement with data from an aerosol mass spectrometer. Furthermore, by taking full advantage of our in situ microreactor concept, we show that the soot particles from all three combustion sources changed their ability to take up water under humid conditions upon photochemical aging of the exhaust. Due to the selectivity and sensitivity of the NEXAFS technique for the water mass, also small amounts of water taken up into the internal voids of agglomerated

Sub-micrometer refractory carbonaceous particles in the polar stratosphere

Science.gov (United States)

Schütze, Katharina; Wilson, James Charles; Weinbruch, Stephan; Benker, Nathalie; Ebert, Martin; Günther, Gebhard; Weigel, Ralf; Borrmann, Stephan

2017-10-01

Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment) from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM) combined with energy-dispersive X-ray microanalysis. A total of 4202 particles (TEM = 3872; SEM = 330) were analyzed from these samples, which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. Particles that were volatile in the microscope beams contained ammonium sulfates and hydrogen sulfates and dominated the samples. Some particles with diameters ranging from 20 to 830 nm were refractory in the electron beams. Carbonaceous particles containing additional elements to C and O comprised from 72 to 100 % of the refractory particles. The rest were internal mixtures of these materials with sulfates. The median number mixing ratio of the refractory particles, expressed in units of particles per milligram of air, was 1.1 (mg air)-1 and varied between 0.65 and 2.3 (mg air)-1. Most of the refractory carbonaceous particles are completely amorphous, a few of the particles are partly ordered with a graphene sheet separation distance of 0.37 ± 0.06 nm (mean value ± standard deviation). Carbon and oxygen are the only detected major elements with an atomic O/C ratio of 0.11 ± 0.07. Minor elements observed include Si, S, Fe, Cr and Ni with the following atomic ratios relative to C: Si/C: 0.010 ± 0.011; S/C: 0.0007 ± 0.0015; Fe/C: 0.0052 ± 0.0074; Cr/C: 0.0012 ± 0.0017; Ni/C: 0.0006 ± 0.0011 (all mean values ± standard deviation).High-resolution element distribution images reveal that the minor elements are distributed within the carbonaceous matrix; i.e., heterogeneous inclusions are not observed. No difference in size, nanostructure and elemental composition was found between particles collected inside and outside the polar vortex. Based on chemistry and nanostructure

On airborne nano/micro-sized wear particles released from low-metallic automotive brakes

International Nuclear Information System (INIS)

Kukutschova, Jana; Moravec, Pavel; Tomasek, Vladimir; Matejka, Vlastimil; Smolik, Jiri; Schwarz, Jaroslav; Seidlerova, Jana; Safarova, Klara; Filip, Peter

2011-01-01

The paper addresses the wear particles released from commercially available 'low-metallic' automotive brake pads subjected to brake dynamometer tests. Particle size distribution was measured in situ and the generated particles were collected. The collected fractions and the original bulk material were analyzed using several chemical and microscopic techniques. The experiments demonstrated that airborne wear particles with sizes between 10 nm and 20 μm were released into the air. The numbers of nanoparticles (<100 nm) were by three orders of magnitude larger when compared to the microparticles. A significant release of nanoparticles was measured when the average temperature of the rotor reached 300 deg. C, the combustion initiation temperature of organics present in brakes. In contrast to particle size distribution data, the microscopic analysis revealed the presence of nanoparticles, mostly in the form of agglomerates, in all captured fractions. The majority of elements present in the bulk material were also detected in the ultra-fine fraction of the wear particles. - Research highlights: → Wear of low-metallic friction composite produces airborne nano-sized particles. → Nano-sized particles contain carbon black and metallic compounds. → Carbon black nano-sized particles are related to resin degradation. → Number of nanoparticles higher by three orders of magnitude than microparticles. - Braking of automobiles may contribute to nano-particulate air pollution caused by friction processes associated with wear of low-metallic brake pads.

Numerical Study of Particle Interaction in Gas-Particle and Liquid-Particle Flows: Part II Particle Response

Directory of Open Access Journals (Sweden)

K. Mohanarangam

2009-09-01

Full Text Available In this paper the numerical model, which was presented in the first paper (Mohanarangam & Tu; 2009 of this series of study, is employed to study the different particle responses under the influence of two carrier phases namely the gas and the liquid. The numerical model takes into consideration the turbulent behaviour of both the carrier and the dispersed phases, with additional equations to take into account the combined fluid particle behaviour, thereby effecting a two-way coupling. The first paper in this series showed the distinct difference in particulate response both at the mean as well as at the turbulent level for two varied carrier phases. In this paper further investigation has been carried out over a broad range of particle Stokes number to further understand their behaviour in turbulent environments. In order to carry out this prognostic study, the backward facing step geometry of Fessler and Eaton (1999 has been adopted, while the inlet conditions for the carrier as well as the particle phases correspond to that of the experiments of Founti and Klipfel (1998. It is observed that at the mean velocity level the particulate velocities increased with a subsequent increase in the Stokes number for both the GP (Gas-Particle as well as the LP (Liquid-Particle flow. It was also observed that across the Stokes number there was a steady increase in the particulate turbulence for the GP flows with successive increase in Stokes number. However, for the LP flows, the magnitude of the increase in the particulate turbulence across the increasing of Stokes number is not as characteristic as the GP flow. Across the same sections for LP flows the majority of the trend shows a decrease after which they remain more or less a constant.

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.

Studies of fast-ion transport induced by energetic particle modes using fast-particle diagnostics with high time resolution in CHS

International Nuclear Information System (INIS)

Isobe, M.; Toi, K.; Suzuki, C.; Nagaoka, K.; Matsushita, H.; Goto, K.

2006-01-01

The purpose of this work is to reveal the effects of the energetic particle mode (EPM) on fast-ion transport and consequent fast-ion loss in the Compact Helical System (CHS). For this purpose, fast particle diagnostics capable of following fast events originating from the EPM (f -5 Tesla at the magnetic probe position. The lost fast-ion probe (LIP) located at the outboard side of the torus indicates that bursting EPMs lead to periodically enhanced losses of co-going fast ions having smaller pitch angles in addition to losses of marginally co-passing fast ions. Coinciding with EPM bursts, the H- light detector viewing the peripheral region at the outboard side also shows large pulsed increases similar to that of the LIP whereas the detector viewing the peripheral region at the inboard side does not. This is also evidence that fast ions are expelled to the outboard side due to the EPM. The charge-exchange neutral particle analyzer indicates that only fast ions whose energy is close to the beam injection energy E b are strongly affected by EPM, suggesting in turn that observed EPMs are excited by fast ions having energy close to E b . (author)

The new classification of elementary particle resonance mass spectra

International Nuclear Information System (INIS)

Gareev, F.A.; Barabanov, M.Yu.; Kazacha, G.S.

1997-01-01

Elementary particle resonances have been systematically analyzed from the first principles: the conservation laws of energy-momentum and Ehrenfest adiabatic invariant. As a result, resonance decay product momenta and masses of resonances were established to be quantized. Radial excited states of resonances were revealed. These observations give us a possibility to formulate the strategy of experimental searches for new resonances and to systematize already known ones. (author)

Quantum private comparison with d-level single-particle states

International Nuclear Information System (INIS)

Yu, Chao-Hua; Guo, Gong-De; Lin, Song

2013-01-01

In this paper, a quantum private comparison protocol with d-level single-particle states is proposed. In the protocol, a semi-honest third party is introduced to help two participants compare the size relationship of their secrets without revealing them to any other people. It is shown that the protocol is secure in theory. Moreover, the security of the protocol in real circumstance is also discussed. (paper)

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

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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.

Accelerating particles in general relativity (stationary C-metric)

International Nuclear Information System (INIS)

Farhoosh, H.

1979-01-01

The purpose of this thesis is to study the physical and geometrical properties of uniformly accelerating particles in the general theory of relativity and it consists of four main parts. In the first part the structure of the Killing horizons in the static vacuum C-metric which represents the gravitational field of a uniformly accelerating Schwarzschild like particle (non-rotating and spherically symmetric) is studied. In the second part these results are generalized to include the effects of the rotation of the source. For small acceleration and small rotation this solution reveals the existance of three Killing horizons. Two the these horizons are the Schwarzschild and the Rindler surfaces which are mainly due to the mass and the acceleration of the particle, respectively. In part three the radial geodesic and non-geodesic motions in the static vacuum C-metric (non-rotating case) are investigated. The effect of the dragging of the inertial frame is also shown in this part. In part four the radiative behavior of the stationary charged C-metric representing the electro-gravitational field of a uniformly accelerating and rotating charged particle with magnetic monopole and the NUT-parameter are investigated. The physical quantities - the news function, mass loss, mass, charge and the multipole moments - are calculated. It is also shown in this part that the magnetic monopole in the presence of rotation and acceleration affects the electric charge

Understanding bulk behavior of particulate materials from particle scale simulations

Science.gov (United States)

Deng, Xiaoliang

Particulate materials play an increasingly significant role in various industries, such as pharmaceutical manufacturing, food, mining, and civil engineering. The objective of this research is to better understand bulk behaviors of particulate materials from particle scale simulations. Packing properties of assembly of particles are investigated first, focusing on the effects of particle size, surface energy, and aspect ratio on the coordination number, porosity, and packing structures. The simulation results show that particle sizes, surface energy, and aspect ratio all influence the porosity of packing to various degrees. The heterogeneous force networks within particle assembly under external compressive loading are investigated as well. The results show that coarse-coarse contacts dominate the strong network and coarse-fine contacts dominate the total network. Next, DEM models are developed to simulate the particle dynamics inside a conical screen mill (comil) and magnetically assisted impaction mixer (MAIM), both are important particle processing devices. For comil, the mean residence time (MRT), spatial distribution of particles, along with the collision dynamics between particles as well as particle and vessel geometries are examined as a function of the various operating parameters such as impeller speed, screen hole size, open area, and feed rate. The simulation results can help better understand dry coating experimental results using comil. For MAIM system, the magnetic force is incorporated into the contact model, allowing to describe the interactions between magnets. The simulation results reveal the connections between homogeneity of mixture and particle scale variables such as size of magnets and surface energy of non-magnets. In particular, at the fixed mass ratio of magnets to non-magnets and surface energy the smaller magnets lead to better homogeneity of mixing, which is in good agreement with previously published experimental results. Last but not

Source apportionment of aerosol particles at a European air pollution hot spot using particle number size distributions and chemical composition.

Science.gov (United States)

Leoni, Cecilia; Pokorná, Petra; Hovorka, Jan; Masiol, Mauro; Topinka, Jan; Zhao, Yongjing; Křůmal, Kamil; Cliff, Steven; Mikuška, Pavel; Hopke, Philip K

2018-03-01

Ostrava in the Moravian-Silesian region (Czech Republic) is a European air pollution hot spot for airborne particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), and ultrafine particles (UFPs). Air pollution source apportionment is essential for implementation of successful abatement strategies. UFPs or nanoparticles of diameter hot-spot including nanoparticles, Positive Matrix Factorization (PMF) was applied to highly time resolved particle number size distributions (NSD, 14 nm-10 μm) and PM 0.09-1.15 chemical composition. Diurnal patterns, meteorological variables, gaseous pollutants, organic markers, and associations between the NSD factors and chemical composition factors were used to identify the pollution sources. The PMF on the NSD reveals two factors in the ultrafine size range: industrial UFPs (28%, number mode diameter - NMD 45 nm), industrial/fresh road traffic nanoparticles (26%, NMD 26 nm); three factors in the accumulation size range: urban background (24%, NMD 93 nm), coal burning (14%, volume mode diameter - VMD 0.5 μm), regional pollution (3%, VMD 0.8 μm) and one factor in the coarse size range: industrial coarse particles/road dust (2%, VMD 5 μm). The PMF analysis of PM 0.09-1.15 revealed four factors: SIA/CC/BB (52%), road dust (18%), sinter/steel (16%), iron production (16%). The factors in the ultrafine size range resolved with NSD have a positive correlation with sinter/steel production and iron production factors resolved with chemical composition. Coal combustion factor resolved with NSD has moderate correlation with SIA/CC/BB factor. The organic markers homohopanes correlate with coal combustion and the levoglucosan correlates with urban background. The PMF applications to NSD and chemical composition datasets are complementary. PAHs in PM 1 were found to be associated with coal combustion factor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis of Monodispersed Spherical Single Crystalline Silver Particles by Wet Chemical Process; Shisshiki kagakuho ni yoru tanbunsankyujo tankesshoginryushi no gose

Energy Technology Data Exchange (ETDEWEB)

Ueyama, Ryousuke.; Harada, Masahiro.; Ueyama, Tamotsu.; Harada, Akio. [Daiken Chemistry Industry Corporation, Osaka (Japan); Yamamoto, Takashi. [National Defence Academy, Kanagawa (Japan). Dept. of Electrical Engineering; Shiosaki, Tadashi. [Nara Institute of Science and Technology, Nara (Japan). Graduate School of Materials Science; Kuribayashi, Kiyoshi. [Teikyo University of Science and Technology, Yamanashi (Japan). Dept. of Materials

1999-01-01

Ultrafine silver monodispersed particle were prepared by wet chemical process. To decrease the reduction speed, an important factor in generating monodispersed particles is to control the following three factors: synthesis temperature, concentration of aggregation-relaxing agent added, and concentration of silver nitrate solution. Synthesis of monodispersed spherical Ag particles, used as metal powders for electrode, became possible using the nucleus grouwth reaction method. This process also allowed the control of the diameter of the powder particles. The silver particles were distributed in ta narrow particle diameter range with on average of 0.5 {mu}m. Transmission electron microscopy (TEM) revealed that single-crystalline silver particles were prepared by the present method. (author)

Particle detection

International Nuclear Information System (INIS)

Charpak, G.

2000-01-01

In this article G.Charpak presents the principles on which particle detection is based. Particle accelerators are becoming more and more powerful and require new detectors able to track the right particle in a huge flux of particles. The gigantic size of detectors in high energy physics is often due to the necessity of getting a long enough trajectory in a magnetic field in order to deduce from the curvature an accurate account of impulses in the reaction. (A.C.)

Analysis of particle kinematics in spheronization via particle image velocimetry.

Science.gov (United States)

Koester, Martin; Thommes, Markus

2013-02-01

Spheronization is a wide spread technique in pellet production for many pharmaceutical applications. Pellets produced by spheronization are characterized by a particularly spherical shape and narrow size distribution. The particle kinematic during spheronization is currently not well-understood. Therefore, particle image velocimetry (PIV) was implemented in the spheronization process to visualize the particle movement and to identify flow patterns, in order to explain the influence of various process parameters. The spheronization process of a common formulation was recorded with a high-speed camera, and the images were processed using particle image velocimetry software. A crosscorrelation approach was chosen to determine the particle velocity at the surface of the pellet bulk. Formulation and process parameters were varied systematically, and their influence on the particle velocity was investigated. The particle stream shows a torus-like shape with a twisted rope-like motion. It is remarkable that the overall particle velocity is approximately 10-fold lower than the tip speed of the friction plate. The velocity of the particle stream can be correlated to the water content of the pellets and the load of the spheronizer, while the rotation speed was not relevant. In conclusion, PIV was successfully applied to the spheronization process, and new insights into the particle velocity were obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

Auroral particles

International Nuclear Information System (INIS)

Evans, D.S.

1987-01-01

The problems concerning the aurora posed prior to the war are now either solved in principle or were restated in a more fundamental form. The pre-war hypothesis concerning the nature of the auroral particles and their energies was fully confirmed, with the exception that helium and oxygen ions were identified as participating in the auroral particle precipitation in addition to the protons. The nature of the near-Earth energization processes affecting auroral particles was clarified. Charged particle trajectories in various electric field geometries were modeled. The physical problems have now moved from determining the nature and geometry of the electric fields, which accelerate charged particles near the Earth, to accounting for the existence of these electric fields as a natural consequence of the solar wind's interaction with Earth. Ultimately the reward in continuing the work in auroral and magnetospheric particle dynamics will be a deeper understanding of the subtleties of classical electricity and magnetism as applied to situations not blessed with well-defined and invariant geometries

Force fields of charged particles in micro-nanofluidic preconcentration systems

Science.gov (United States)

Gong, Lingyan; Ouyang, Wei; Li, Zirui; Han, Jongyoon

2017-12-01

Electrokinetic concentration devices based on the ion concentration polarization (ICP) phenomenon have drawn much attention due to their simple setup, high enrichment factor, and easy integration with many subsequent processes, such as separation, reaction, and extraction etc. Despite significant progress in the experimental research, fundamental understanding and detailed modeling of the preconcentration systems is still lacking. The mechanism of the electrokinetic trapping of charged particles is currently limited to the force balance analysis between the electric force and fluid drag force in an over-simplified one-dimensional (1D) model, which misses many signatures of the actual system. This letter studies the particle trapping phenomena that are not explainable in the 1D model through the calculation of the two-dimensional (2D) force fields. The trapping of charged particles is shown to significantly distort the electric field and fluid flow pattern, which in turn leads to the different trapping behaviors of particles of different sizes. The mechanisms behind the protrusions and instability of the focused band, which are important factors determining overall preconcentration efficiency, are revealed through analyzing the rotating fluxes of particles in the vicinity of the ion-selective membrane. The differences in the enrichment factors of differently sized particles are understood through the interplay between the electric force and convective fluid flow. These results provide insights into the electrokinetic concentration effect, which could facilitate the design and optimization of ICP-based preconcentration systems.

Neutron activation analysis of small particles brought back from the asteroid Itokawa by the space probe Hayabusa

International Nuclear Information System (INIS)

Ebihara, Mitsuru

2013-01-01

The probe in the title launched in May 2003, landed on the asteroid 25143 (Itokawa) to collect the surface material, and returned to the desert of Australia in June 2010. The material carried in Japan Aerospace Exploration Agency (JAXA) was found to be >1,500 particles of extraterrestrial origin. This paper reports the results of activation analysis of a part of particles for the purpose of characterizing the elemental composition. The size of particles was mostly <100 mc-m and the mass, several 10s mc-g. The experiment was performed preliminarily on Kilabo meteorite using Kyoto University Research Reactor (KURR) as a neutron source, and then on 1 Itokawa particle named RA-QD02-0049, which was activated for 19 hr. The cooled particle was found to be split mainly in 2 parts (0049-1 and -2), which were subjected to analysis of gamma ray with Ge semiconductor detector in the KURR Institute and Kanazawa University. Analysis revealed that the 2 particles contained 8 elements of Na, Sc, Cr, Fe, Co, Ni, Zn and Ir, which were then quantitated with similarly neutron irradiated Allende meteorite, basalt JB-1 and highly purified Fe, and with previous findings by scanning electron microscope with energy dispersive X-ray spectrometer (SEM-EDX) showing the Itokawa particle was an olivine. Finally, 0049-1 and -2 were found to be of mass of 1.6 and 1.5 mc-g, respectively, based on which the calculated contents of the 8 elements revealed that they were homogeneously existed in the Itokawa particle. Comparison of elemental composition of the particle with those of various intra- and extra-terrestrial rocks and meteorites suggested that Itokawa had a feature of elements aggregated at the early stage after formation of the solar system 4.5 billion years ago. (T.T.)

Thermodynamics of phase-separating nanoalloys: Single particles and particle assemblies

Science.gov (United States)

Fèvre, Mathieu; Le Bouar, Yann; Finel, Alphonse

2018-05-01

The aim of this paper is to investigate the consequences of finite-size effects on the thermodynamics of nanoparticle assemblies and isolated particles. We consider a binary phase-separating alloy with a negligible atomic size mismatch, and equilibrium states are computed using off-lattice Monte Carlo simulations in several thermodynamic ensembles. First, a semi-grand-canonical ensemble is used to describe infinite assemblies of particles with the same size. When decreasing the particle size, we obtain a significant decrease of the solid/liquid transition temperatures as well as a growing asymmetry of the solid-state miscibility gap related to surface segregation effects. Second, a canonical ensemble is used to analyze the thermodynamic equilibrium of finite monodisperse particle assemblies. Using a general thermodynamic formulation, we show that a particle assembly may split into two subassemblies of identical particles. Moreover, if the overall average canonical concentration belongs to a discrete spectrum, the subassembly concentrations are equal to the semi-grand-canonical equilibrium ones. We also show that the equilibrium of a particle assembly with a prescribed size distribution combines a size effect and the fact that a given particle size assembly can adopt two configurations. Finally, we have considered the thermodynamics of an isolated particle to analyze whether a phase separation can be defined within a particle. When studying rather large nanoparticles, we found that the region in which a two-phase domain can be identified inside a particle is well below the bulk phase diagram, but the concentration of the homogeneous core remains very close to the bulk solubility limit.

Preparation of hierarchical porous Zn-salt particles and their superhydrophobic performance

Energy Technology Data Exchange (ETDEWEB)

Gao, Dahai; Jia, Mengqiu, E-mail: jiamq@mail.buct.edu.cn

2015-12-30

Graphical abstract: - Highlights: • Hierarchical particles with high roughness were prepared by modified hydrothermal route. • The high roughness is provided by extremely low thickness of sheet crystals. • FEVE polymer derivative was used for surface treatment of hierarchical surface. • The novel particles via surface treatment were firstly used as superhydrophobic materials. • The product properties were compared with multi-scale ZnO particles via conventional route. - Abstract: Superhydrophobic surfaces arranged by hierarchical porous particles were prepared using modified hydrothermal routes under the effect of sodium citrate. Two particle samples were generated in the medium of hexamethylenetetramine (P1) and urea (P2), respectively. X-ray diffraction, scanning electron microscope, and transmission electron microscope were adopted for the investigation, and results revealed that the P1 and P2 particles are porous microspheres with crosslinked extremely thin (10–30 nm) sheet crystals composed of Zn{sub 5}(OH){sub 8}Ac{sub 2}·2H{sub 2}O and Zn{sub 5}(CO{sub 3}){sub 2}(OH){sub 6}, respectively. The prepared particles were treated with a fluoroethylene vinyl ether derivative and studied using Fourier transform infrared spectroscopy and energy-dispersive X-ray spectrometer. Results showed that the hierarchical surfaces of these particles were combined with low-wettable fluorocarbon layers. Moreover, the fabricated surface composed of the prepared hierarchical particles displayed considerably high contact angles, indicating great superhydrophobicity for the products. The wetting behavior of the particles was analyzed with a theoretical wetting model in comparison with that of chestnut-like ZnO products obtained through a conventional hydrothermal route. Correspondingly, this study provided evidence that high roughness surface plays a great role in superhydrophobic behavior.

Single-particle characterization of ice-nucleating particles and ice particles residuals sampled by three different techniques

Science.gov (United States)

Kandler, Konrad; Worringen, Annette; Benker, Nathalie; Dirsch, Thomas; Mertes, Stephan; Schenk, Ludwig; Kästner, Udo; Frank, Fabian; Nillius, Björn; Bundke, Ulrich; Rose, Diana; Curtius, Joachim; Kupiszewski, Piotr; Weingartner, Ernest; Vochezer, Paul; Schneider, Johannes; Schmidt, Susan; Weinbruch, Stephan; Ebert, Martin

2015-04-01

During January/February 2013, at the High Alpine Research Station Jungfraujoch a measurement campaign was carried out, which was centered on atmospheric ice-nucleating particles (INP) and ice particle residuals (IPR). Three different techniques for separation of INP and IPR from the non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed phase clouds and allow for the analysis of the residuals. The combination of the Fast Ice Nucleus Chamber (FINCH) and the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated INP for analysis. Collected particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine size, chemical composition and mixing state. All INP/IPR-separating techniques had considerable abundances (median 20 - 70 %) of instrumental contamination artifacts (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH+IN-PCVI: steel particles). Also, potential sampling artifacts (e.g., pure soluble material) occurred with a median abundance of separated by all three techniques. Soot was a minor contributor. Lead was detected in less than 10 % of the particles, of which the majority were internal mixtures with other particle types. Sea-salt and sulfates were identified by all three methods as INP/IPR. Most samples showed a maximum of the INP/IPR size distribution at 400 nm geometric diameter. In a few cases, a second super-micron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the submicron range. ISI and FINCH yielded silicates and Ca-rich particles mainly with diameters above 1 µm, while the Ice-CVI also separated many submicron IPR. As strictly parallel sampling could not be performed, a part of the discrepancies between the different techniques may result from

Multiplicity dependence of 2-particle correlations in proton-proton collisions measured with ALICE at the LHC

International Nuclear Information System (INIS)

Sicking, E.

2014-01-01

We investigate properties of jets in proton-proton collisions using 2-particle angular correlations. By choosing an analysis approach based on 2-particle angular correlations, also the properties of low-energetic jets can be accessed. Observing the strength of the correlation as a function of the charged particle multiplicity reveals jet fragmentation properties as well as the contribution of jets to the overall charged particle multiplicity. Furthermore, the analysis discloses information on the underlying multiple parton interactions. We present results from proton-proton collisions at the center-of-mass energies √(s) = 0.9, 2.76 and 7 TeV recorded by the ALICE experiment. The ALICE data are compared to Pythia6, Pythia8 and Phojet simulations. (author)

Multiplicity Dependence of Two-Particle Correlations in Proton-Proton Collisions Measured with ALICE at the LHC

CERN Document Server

Sicking, Eva

2012-01-01

We investigate properties of jets in proton-proton collisions using two-particle angular correlations. By choosing an analysis approach based on two-particle angular correlations, also the properties of low-energetic jets can be accessed. Observing the strength of the correlation as a function of the charged particle multiplicity reveals jet fragmentation properties as well as the contribution of jets to the overall charged particle multiplicity. Furthermore, the analysis discloses information on the underlying multiple parton interactions. We present results from proton-proton collisions at the center-of-mass energies $\\sqrt{s}$ = 0.9, 2.76, and 7.0 TeV recorded by the ALICE experiment. The ALICE data are compared to Pythia6, Pythia8, and Phojet simulations.

Fission Product Release Behavior of Individual Coated Fuel Particles for High-Temperature Gas-Cooled Reactors

International Nuclear Information System (INIS)

Minato, Kazuo; Sawa, Kazuhiro; Koya, Toshio; Tomita, Takeshi; Ishikawa, Akiyoshi; Baldwin, Charles A.; Gabbard, William Alexander; Malone, Charlie M.

2000-01-01

Postirradiation heating tests of TRISO-coated UO 2 particles at 1700 and 1800degC were performed to understand fission product release behavior at accident temperatures. The inventory measurements of the individual particles were carried out before and after the heating tests with gamma-ray spectrometry to study the behavior of the individual particles. The time-dependent release behavior of 85 Kr, 110m Ag, 134 Cs, 137 Cs, and 154 Eu were obtained with on-line measurements of fission gas release and intermittent measurements of metallic fission product release during the heating tests. The inventory measurements of the individual particles revealed that fission product release behavior of the individual particles was not uniform, and large particle-to-particle variations in the release behavior of 110m Ag, 134 Cs, 137 Cs, and 154 Eu were found. X-ray microradiography and ceramography showed that the variations could not be explained by only the presence or absence of cracks in the SiC coating layer. The SiC degradation may have been related to the variations

Primary particles and their agglomerate formation as modifying risk factors of nonfibrous nanosized dust.

Science.gov (United States)

Schneider, J; Walter, D; Brückel, B; Rödelsperger, K

2013-01-01

The incidence of certain cancers correlates with the number of dust particles in the air. Nanosized particles differ from coarser particles by their increasing tendency to form agglomerates. The dissociation of biodurable agglomerates after deposition in the alveolar region resulted in a higher toxic potential. Biodurable dusts in the urban and workplace environment were analyzed to determine an effect-relevant exposure parameter. The characterization of the dusts relating to their number of primary particles (P(p)) and agglomerates and aggregates (A + A) was performed by electron microscopy. Diesel soot, toner material, and seven further dust samples in the workplace environment are composed of high numbers of nanosized primary particles (agglomerates. Primary particles of rock, kaoline, and seven further dusts sampled in the workplace are not nanosized. In a multivariate analysis that predicted lung tumor risk, the mass, volume, and numbers of A + A and P(p) per milligram dust were shown to be relevant parameters. Dose-response relationships revealed an increased tumor risk in rats with higher numbers of P(p) in nanosized dust, which occurs unintentionally in the environment.

Molecular Mechanisms of Particle Ration Induced Apoptosis in Lymphocyte

Science.gov (United States)

Shi, Yufang

Space radiation, composed of high-energy charged nuclei (HZE particles) and protons, has been previously shown to severely impact immune homeostasis in mice. To determine the molecular mechanisms that mediate acute lymphocyte depletion following exposure to HZE particle radiation mice were exposed to particle radiation beams at Brookhaven National Laboratory. We found that mice given whole body 5 6Fe particle irradiation (1GeV /n) had dose-dependent losses in total lymphocyte numbers in the spleen and thymus (using 200, 100 and 50 cGy), with thymocytes being more sensitive than splenocytes. All phenotypic subsets were reduced in number. In general, T cells and B cells were equally sensitive, while CD8+ T cells were more senstive than CD4+ T cells. In the thymus, immature CD4+CD8+ double-positive thymocytes were exquisitely sensitive to radiation-induced losses, single-positive CD4 or CD8 cells were less sensitive, and the least mature double negative cells were resistant. Irradiation of mice deficient in genes encoding essential apoptosis-inducing proteins revealed that the mechanism of lymphocyte depletion is independent of Fas ligand and TRAIL (TNF-ralated apoptosis-inducing ligand), in contrast to γ-radiation-induced lymphocyte losses which require the Fas-FasL pathway. Using inhibitors in vitro, lymphocyte apoptosis induced by HZE particle radiation was found to be caspase dependent, and not involve nitric oxide or oxygen free radicals.

Visualization of acoustic particle interaction and agglomeration: Theory evaluation

International Nuclear Information System (INIS)

Hoffmann, T.L.; Koopmann, G.H.

1997-01-01

In this paper experimentally observed trajectories of particles undergoing acoustically induced interaction and agglomeration processes are compared to and validated with numerically generated trajectories based on existing agglomeration theories. Models for orthokinetic, scattering, mutual radiation pressure, and hydrodynamic particle interaction are considered in the analysis. The characteristic features of the classical orthokinetic agglomeration hypothesis, such as collision processes and agglomerations due to the relative entrainment motion, are not observed in the digital images. The measured entrainment rates of the particles are found to be consistently lower than the theoretically predicted values. Some of the experiments reveal certain characteristics which may possibly be related to mutual scattering interaction. The study's most significant discovery is the so-called tuning fork agglomeration [T. L. Hoffmann and G. H. Koopmann, J. Acoust. Soc. Am. 99, 2130 endash 2141 (1996)]. It is shown that this phenomenon contradicts the theories for mutual scattering interaction and mutual radiation pressure interaction, but agrees with the acoustic wake effect model in its intrinsic feature of attraction between particles aligned along the acoustic axis. A model by Dianov et al. [Sov. Phys. Acoust. 13 (3), 314 endash 319 (1968)] is used to describe this effect based on asymmetric flow fields around particles under Oseen flow conditions. It is concluded that this model is consistent with the general characteristics of the tuning fork agglomerations, but lacks certain refinements with respect to accurate quantification of the effect. copyright 1997 Acoustical Society of America

Particle creation by a black hole as a consequence of quantum-field effects in flat space-time

International Nuclear Information System (INIS)

Nugayev, R.M.

1985-01-01

The application of quantum-field flat-space-time results to a black hole reveals the domain and the mechanism of particle creation. The Hawking radiation is ''squeezed out'' by the tail of gravitational-field potential barrier in the [1.5 Rg, infinity] region. Its black-body spectrum is due to the interaction of virtual particles with the ''cavity'' formed by the potential barrier

Online single particle analysis of ice particle residuals from mountain-top mixed-phase clouds using laboratory derived particle type assignment

Science.gov (United States)

Schmidt, Susan; Schneider, Johannes; Klimach, Thomas; Mertes, Stephan; Schenk, Ludwig Paul; Kupiszewski, Piotr; Curtius, Joachim; Borrmann, Stephan

2017-01-01

In situ single particle analysis of ice particle residuals (IPRs) and out-of-cloud aerosol particles was conducted by means of laser ablation mass spectrometry during the intensive INUIT-JFJ/CLACE campaign at the high alpine research station Jungfraujoch (3580 m a.s.l.) in January-February 2013. During the 4-week campaign more than 70 000 out-of-cloud aerosol particles and 595 IPRs were analyzed covering a particle size diameter range from 100 nm to 3 µm. The IPRs were sampled during 273 h while the station was covered by mixed-phase clouds at ambient temperatures between -27 and -6 °C. The identification of particle types is based on laboratory studies of different types of biological, mineral and anthropogenic aerosol particles. The outcome of these laboratory studies was characteristic marker peaks for each investigated particle type. These marker peaks were applied to the field data. In the sampled IPRs we identified a larger number fraction of primary aerosol particles, like soil dust (13 ± 5 %) and minerals (11 ± 5 %), in comparison to out-of-cloud aerosol particles (2.4 ± 0.4 and 0.4 ± 0.1 %, respectively). Additionally, anthropogenic aerosol particles, such as particles from industrial emissions and lead-containing particles, were found to be more abundant in the IPRs than in the out-of-cloud aerosol. In the out-of-cloud aerosol we identified a large fraction of aged particles (31 ± 5 %), including organic material and secondary inorganics, whereas this particle type was much less abundant (2.7 ± 1.3 %) in the IPRs. In a selected subset of the data where a direct comparison between out-of-cloud aerosol particles and IPRs in air masses with similar origin was possible, a pronounced enhancement of biological particles was found in the IPRs.

Violation of Particle Anti-particle Symmetry

CERN Multimedia

CERN. Geneva

2001-01-01

Symmetry is a fundamental concept which can be found in the whole range of human activities e. g. from arts to science. The beauty of a statues is often related to its symmetric form. In physics, all the laws are related to some sort of symmetry. Equally important is a small breakdown ofsymmetry. Even for the case of a statue, its beauty might be enhanced by introducing small distortions. In this course, we investigate the role symmetry in the world of elementary particles. Some symmetries found there are very similar to those which can be seen in our daily life, while others are more exotic and related to the quantum nature of the elementary particles. Our particular focus ismade on symmetry and its violation between the matter and anti-matter, known as CP violation. It is experimentally well established that particleand anti-particle behave a tiny bit differently in the world of elementary particles. We discuss how this would be explained and how we can extendour knowledge. Evolution of our universe is stro...

Accurate particle speed prediction by improved particle speed measurement and 3-dimensional particle size and shape characterization technique

DEFF Research Database (Denmark)

Cernuschi, Federico; Rothleitner, Christian; Clausen, Sønnik

2017-01-01

Accurate particle mass and velocity measurement is needed for interpreting test results in erosion tests of materials and coatings. The impact and damage of a surface is influenced by the kinetic energy of a particle, i.e. particle mass and velocity. Particle mass is usually determined with optic...

Particle-based model for skiing traffic.

Science.gov (United States)

Holleczek, Thomas; Tröster, Gerhard

2012-05-01

We develop and investigate a particle-based model for ski slope traffic. Skiers are modeled as particles with a mass that are exposed to social and physical forces, which define the riding behavior of skiers during their descents on ski slopes. We also report position and speed data of 21 skiers recorded with GPS-equipped cell phones on two ski slopes. A comparison of these data with the trajectories resulting from computer simulations of our model shows a good correspondence. A study of the relationship among the density, speed, and flow of skiers reveals that congestion does not occur even with arrival rates of skiers exceeding the maximum ski lift capacity. In a sensitivity analysis, we identify the kinetic friction coefficient of skis on snow, the skier mass, the range of repelling social forces, and the arrival rate of skiers as the crucial parameters influencing the simulation results. Our model allows for the prediction of speed zones and skier densities on ski slopes, which is important in the prevention of skiing accidents.

Alumina particle degradation during solid particle impact on glass

NARCIS (Netherlands)

Slikkerveer, P.J.; Veld, in 't H.; Verspui, M.A.; With, de G.; Reefman, D.

2000-01-01

Particle degradation limits the reuse of powders in industrial powder-blast processes. In this paper the degradation behavior of Al2O3 powder is studied during erosion of glass substrates. Three techniques were used on original and multiply used powders: particle size measurements, single particle

Particle-gamma and particle-particle correlations in nuclear reactions using Monte Carlo Hauser-Feshback model

Energy Technology Data Exchange (ETDEWEB)

Kawano, Toshihiko [Los Alamos National Laboratory; Talou, Patrick [Los Alamos National Laboratory; Watanabe, Takehito [Los Alamos National Laboratory; Chadwick, Mark [Los Alamos National Laboratory

2010-01-01

Monte Carlo simulations for particle and {gamma}-ray emissions from an excited nucleus based on the Hauser-Feshbach statistical theory are performed to obtain correlated information between emitted particles and {gamma}-rays. We calculate neutron induced reactions on {sup 51}V to demonstrate unique advantages of the Monte Carlo method. which are the correlated {gamma}-rays in the neutron radiative capture reaction, the neutron and {gamma}-ray correlation, and the particle-particle correlations at higher energies. It is shown that properties in nuclear reactions that are difficult to study with a deterministic method can be obtained with the Monte Carlo simulations.

Colloids exposed to random potential energy landscapes: From particle number density to particle-potential and particle-particle interactions

International Nuclear Information System (INIS)

Bewerunge, Jörg; Capellmann, Ronja F.; Platten, Florian; Egelhaaf, Stefan U.; Sengupta, Ankush; Sengupta, Surajit

2016-01-01

Colloidal particles were exposed to a random potential energy landscape that has been created optically via a speckle pattern. The mean particle density as well as the potential roughness, i.e., the disorder strength, were varied. The local probability density of the particles as well as its main characteristics were determined. For the first time, the disorder-averaged pair density correlation function g (1) (r) and an analogue of the Edwards-Anderson order parameter g (2) (r), which quantifies the correlation of the mean local density among disorder realisations, were measured experimentally and shown to be consistent with replica liquid state theory results.

Magnetic particles

Science.gov (United States)

Chang, Manchium (Inventor); Colvin, Michael S. (Inventor)

1989-01-01

Magnetic polymer particles are formed by swelling porous, polymer particles and impregnating the particles with an aqueous solution of precursor magnetic metal salt such as an equimolar mixture of ferrous chloride and ferric chloride. On addition of a basic reagent such as dilute sodium hydroxide, the metal salts are converted to crystals of magnetite which are uniformly contained througout the pores of the polymer particle. The magnetite content can be increased and neutral buoyancy achieved by repetition of the impregnaton and neutralization steps to adjust the magnetite content to a desired level.

Characterization of complete particles (VSV-G/SIN-GFP) and empty particles (VSV-G/EMPTY) in human immunodeficiency virus type 1-based lentiviral products for gene therapy: potential applications for improvement of product quality and safety.

Science.gov (United States)

Zhao, Yuan; Keating, Kenneth; Dolman, Carl; Thorpe, Robin

2008-05-01

Lentiviral vectors persist in the host and are therefore ideally suited for long-term gene therapy. To advance the use of lentiviral vectors in humans, improvement of their production, purification, and characterization has become increasingly important and challenging. In addition to cellular contaminants derived from packaging cells, empty particles without therapeutic function are the major impurities that compromise product safety and efficacy. Removal of empty particles is difficult because of their innate similarity in particle size and protein composition to the complete particles. We propose that comparison of the properties of lentiviral products with those of purposely expressed empty particles may reveal potential differences between empty and complete particles. For this, three forms of recombinant lentiviral samples, that is, recombinant vesicular stomatitis virus glycoprotein (VSV-G) proteins, empty particles (VSV-G/Empty), and complete particles (VSV-G/SIN-GFP) carrying viral RNA, were purified by size-exclusion chromatography (SEC). The SEC-purified samples were further analyzed by immunoblotting with six antibodies to examine viral and cellular proteins associated with the particles. This study has demonstrated, for the first time, important differences between VSV-G/Empty particles and complete VSV-G/SIN-GFP particles. Differences include the processing of Gag protein and the inclusion of cellular proteins in the particles. Our findings support the development of improved production, purification, and characterization methods for lentiviral products.

Study of neutral particle behavior and particle confinement in JT-60U

International Nuclear Information System (INIS)

Takenaga, Hidenobu; Shimizu, Katsuhiro; Asakura, Nobuyuki; Shimada, Michiya; Kikuchi, Mitsuru; Tsuji-Iio, Shunji; Uchino, Kiichiro; Muraoka, Katsunori.

1995-07-01

In order to understand the particle confinement properties in JT-60U, the particle confinement time was estimated through analyses of the neutral particle behavior. First, the neutral particle transport simulation code DEGAS using a Monte-Carlo technique was combined with the simple divertor code for calculating the edge plasma parameters, and was developed to calculate under the experimental conditions in JT-60U. Then, the charged particle source in the main plasma due to the ionization of the neutral particles was evaluated from the analyses of the neutral particle penetration to the main plasma based on results of the simulation code and measurements of D α emission intensities. Finally, the particle confinement time was estimated from the analysis of particle balance. The analyses were performed systematically for the L-mode plasma and H-mode plasma of JT-60U, and a data base of the particle confinement time was obtained. The dependence of the particle confinement time on the plasma parameters and the relationship between the properties of the particle confinement and the energy confinement were examined. (author)

Two types of amorphous protein particles facilitate crystal nucleation.

Science.gov (United States)

Yamazaki, Tomoya; Kimura, Yuki; Vekilov, Peter G; Furukawa, Erika; Shirai, Manabu; Matsumoto, Hiroaki; Van Driessche, Alexander E S; Tsukamoto, Katsuo

2017-02-28

Nucleation, the primary step in crystallization, dictates the number of crystals, the distribution of their sizes, the polymorph selection, and other crucial properties of the crystal population. We used time-resolved liquid-cell transmission electron microscopy (TEM) to perform an in situ examination of the nucleation of lysozyme crystals. Our TEM images revealed that mesoscopic clusters, which are similar to those previously assumed to consist of a dense liquid and serve as nucleation precursors, are actually amorphous solid particles (ASPs) and act only as heterogeneous nucleation sites. Crystalline phases never form inside them. We demonstrate that a crystal appears within a noncrystalline particle assembling lysozyme on an ASP or a container wall, highlighting the role of heterogeneous nucleation. These findings represent a significant departure from the existing formulation of the two-step nucleation mechanism while reaffirming the role of noncrystalline particles. The insights gained may have significant implications in areas that rely on the production of protein crystals, such as structural biology, pharmacy, and biophysics, and for the fundamental understanding of crystallization mechanisms.

Magnetically tunable elasticity for magnetic hydrogels consisting of carrageenan and carbonyl iron particles.

Science.gov (United States)

Mitsumata, Tetsu; Honda, Atomu; Kanazawa, Hiroki; Kawai, Mika

2012-10-11

A new class of magnetoelastic gel that demonstrates drastic and reversible changes in storage modulus without using strong magnetic fields was obtained. The magnetic gel consists of carrageenan and carbonyl iron particles. The magnetic gel with a volume fraction of magnetic particles of 0.30 exhibited a reversible increase by a factor of 1400 of the storage modulus upon a magnetic field of 500 mT, which is the highest value in the past for magnetorheological soft materials. It is considered that the giant magnetoelastic behavior is caused by both high dispersibility and high mobility of magnetic particles in the carrageenan gel. The off-field storage modulus of the magnetic gel at volume fractions below 0.30 obeyed the Krieger-Dougherty equation, indicating random dispersion of magnetic particles. At 500 mT, the storage modulus was higher than 4.0 MPa, which is equal to that of magnetic fluids, indicating that the magnetic particles move and form a chain structure by magnetic fields. Morphological study revealed the evidence that the magnetic particles embedded in the gel were aligned in the direction of magnetic fields, accompanied by stretching of the gel network. We conclude that the giant magnetoelastic phenomenon originates from the chain structure consisting of magnetic particles similar to magnetic fluids.

Soot Particle Size Distribution Functions in a Turbulent Non-Premixed Ethylene-Nitrogen Flame

KAUST Repository

Boyette, Wesley

2017-02-21

A scanning mobility particle sizer with a nano differential mobility analyzer was used to measure nanoparticle size distribution functions in a turbulent non-premixed flame. The burner utilizes a premixed pilot flame which anchors a C2H4/N2 (35/65) central jet with ReD = 20,000. Nanoparticles in the flame were sampled through a N2-filled tube with a 500- μm orifice. Previous studies have shown that insufficient dilution of the nanoparticles can lead to coagulation in the sampling line and skewed particle size distribution functions. A system of mass flow controllers and valves were used to vary the dilution ratio. Single-stage and two-stage dilution systems were investigated. A parametric study on the effect of the dilution ratio on the observed particle size distribution function indicates that particle coagulation in the sampling line can be eliminated using a two-stage dilution process. Carbonaceous nanoparticle (soot) concentration particle size distribution functions along the flame centerline at multiple heights in the flame are presented. The resulting distributions reveal a pattern of increasing mean particle diameters as the distance from the nozzle along the centerline increases.

Soot Particle Size Distribution Functions in a Turbulent Non-Premixed Ethylene-Nitrogen Flame

KAUST Repository

Boyette, Wesley; Chowdhury, Snehaunshu; Roberts, William L.

2017-01-01

A scanning mobility particle sizer with a nano differential mobility analyzer was used to measure nanoparticle size distribution functions in a turbulent non-premixed flame. The burner utilizes a premixed pilot flame which anchors a C2H4/N2 (35/65) central jet with ReD = 20,000. Nanoparticles in the flame were sampled through a N2-filled tube with a 500- μm orifice. Previous studies have shown that insufficient dilution of the nanoparticles can lead to coagulation in the sampling line and skewed particle size distribution functions. A system of mass flow controllers and valves were used to vary the dilution ratio. Single-stage and two-stage dilution systems were investigated. A parametric study on the effect of the dilution ratio on the observed particle size distribution function indicates that particle coagulation in the sampling line can be eliminated using a two-stage dilution process. Carbonaceous nanoparticle (soot) concentration particle size distribution functions along the flame centerline at multiple heights in the flame are presented. The resulting distributions reveal a pattern of increasing mean particle diameters as the distance from the nozzle along the centerline increases.

Decoupling Subtraction Conserving Full Gauge Symmetries : Particles and Fields

OpenAIRE

Noriyasu, OHTSUBO; Hideo, MIYATA; Department of Phycics, Kanazawa Technical College; Department of Information Science, Kanazawa Institute of Technolgy

1984-01-01

A new subtraction scheme (^^^) which realizes the decoupling and conserves the symmetries of full gauge group simultaneously, is proposed. One particle irreducible Green's functions subtracted by ^^^ reveal the effective low energy symmetries at -p^2≪M^2 and the full symmetries at -p^2≫M^2, where M denotes a heavy mass. Also discussed are conditions in order to carry out ^^^ under two-loop approximation.

Atypical energetic particle events observed prior energetic particle enhancements associated with corotating interaction regions

Science.gov (United States)

Khabarova, Olga; Malandraki, Olga; Zank, Gary; Jackson, Bernard; Bisi, Mario; Desai, Mihir; Li, Gang; le Roux, Jakobus; Yu, Hsiu-Shan

2017-04-01

Recent studies of mechanisms of particle acceleration in the heliosphere have revealed the importance of the comprehensive analysis of stream-stream interactions as well as the heliospheric current sheet (HCS) - stream interactions that often occur in the solar wind, producing huge magnetic cavities bounded by strong current sheets. Such cavities are usually filled with small-scale magnetic islands that trap and re-accelerate energetic particles (Zank et al. ApJ, 2014, 2015; le Roux et al. ApJ, 2015, 2016; Khabarova et al. ApJ, 2015, 2016). Crossings of these regions are associated with unusual variations in the energetic particle flux up to several MeV/nuc near the Earth's orbit. These energetic particle flux enhancements called "atypical energetic particle events" (AEPEs) are not associated with standard mechanisms of particle acceleration. The analysis of multi-spacecraft measurements of energetic particle flux, plasma and the interplanetary magnetic field shows that AEPEs have a local origin as they are observed by different spacecraft with a time delay corresponding to the solar wind propagation from one spacecraft to another, which is a signature of local particle acceleration in the region embedded in expanding and rotating background solar wind. AEPEs are often observed before the arrival of corotating interaction regions (CIRs) or stream interaction regions (SIRs) to the Earth's orbit. When fast solar wind streams catch up with slow solar wind, SIRs of compressed heated plasma or more regular CIRs are created at the leading edge of the high-speed stream. Since coronal holes are often long-lived structures, the same CIR re-appears often for several consecutive solar rotations. At low heliographic latitudes, such CIRs are typically bounded by forward and reverse waves on their leading and trailing edges, respectively, that steepen into shocks at heliocentric distances beyond 1 AU. Energetic ion increases have been frequently observed in association with CIR

Measurements of meteor smoke particles during the ECOMA-2006 campaign: 2. Results

Science.gov (United States)

Strelnikova, Irina; Rapp, Markus; Strelnikov, Boris; Baumgarten, Gerd; Brattli, Alvin; Svenes, Knut; Hoppe, Ulf-Peter; Friedrich, Martin; Gumbel, Jörg; Williams, Bifford P.

2009-03-01

The first sounding rocket of the European ECOMA-project (ECOMA, Existence and Charge state Of Meteoric smoke particles in the middle Atmosphere) was launched on 8 September 2006. Measurements with a new particle detector described in the companion paper by Rapp and Strelnikova [2008. Measurements of meteor smoke particles during the ECOMA-2006 campaign: 1. Particle detection by active photoionization. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.06.002] clearly showed meteor smoke particle (MSP) signatures in both data channels. The data channels measure particles directly impacting on the detector electrode and photoelectrons from the particles actively created using ionization by the UV-photons of a xenon-flashlamp. Measured photoelectron currents resemble model expectations of the shape of the MSP layer almost perfectly, whereas derived number densities in the altitude range 60-90 km are larger than model results by about a factor of 5. Given the large uncertainties inherent to both model and the analysis of our measurements (e.g., the composition of the particles is not known and must be assumed) we consider this a satisfactory agreement and proof that MSPs do extend throughout the entire mesosphere as predicted by models. The measurements of direct particle impacts revealed a confined layer of negative charge between 80 and 90 km. This limited altitude range, however, is quantitatively shown to be the consequence of the aerodynamics of the rocket flight and does not have any geophysical origin. Measured charge signatures are consistent with expectations of particle charging given our own measurements of the background ionization. Unfortunately, however, a contamination of these measurements from triboelectric charging cannot be excluded at this stage.

Peak-locking reduction for particle image velocimetry

International Nuclear Information System (INIS)

Michaelis, Dirk; Wieneke, Bernhard; Neal, Douglas R

2016-01-01

A parametric study of the factors contributing to peak-locking, a known bias error source in particle image velocimetry (PIV), is conducted using synthetic data that are processed with a state-of-the-art PIV algorithm. The investigated parameters include: particle image diameter, image interpolation techniques, the effect of asymmetric versus symmetric window deformation, number of passes and the interrogation window size. Some of these parameters are found to have a profound effect on the magnitude of the peak-locking error. The effects for specific PIV cameras are also studied experimentally using a precision turntable to generate a known rotating velocity field. Image time series recorded using this experiment show a linear range of pixel and sub-pixel shifts ranging from 0 to  ±4 pixels. Deviations in the constant vorticity field (ω z ) reveal how peak-locking can be affected systematically both by varying parameters of the detection system such as the focal distance and f -number, and also by varying the settings of the PIV analysis. A new a priori technique for reducing the bias errors associated with peak-locking in PIV is introduced using an optical diffuser to avoid undersampled particle images during the recording of the raw images. This technique is evaluated against other a priori approaches using experimental data and is shown to perform favorably. Finally, a new a posteriori anti peak-locking filter (APLF) is developed and investigated, which shows promising results for both synthetic data and real measurements for very small particle image sizes. (paper)

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

Electrostatics of spherical metallic particles in cylinder electrostatic separators/sizers

International Nuclear Information System (INIS)

Lu Hongzhou; Li Jia; Guo Jie; Xu Zhenming

2006-01-01

This paper presents a theoretical analysis of the dynamics of spherical metallic particles in electrostatic separators/sizers (ESSs). A computational algorithm is employed to depict the cylinder-type electrode arrangements applied in some electrostatic processes generating non-uniform electric fields. The ESS consists of a pair of conducting cylinders. The upper cylinder is energized by HVdc, while the lower one is grounded and mounted horizontally on a revolvable axis. The aim of this paper is to present a new electrode configuration and demonstrate the usefulness of numerical techniques for the evaluation of the particle's motion. A computer program was employed for analysing the behavior of spherical particles in a two-dimensional electrode arrangement that models the actual electric field configuration of cylinder-type electrostatic separators/sizers. The analysis is needed for the development of any new application of this cylinder-type electrode arrangement as an electrostatic separation method. The results reveal that the particle's motion depends on its radius and density and amplitude of the applied voltage. The actual granular mixtures with different specific mass and radius could be separated applying this cylinder-type electrostatic separation method; the lift voltage is an important parameter for separation. With a program for two-dimensional analysis of the electric field, the computational procedure presented in this paper could be employed for any particle shapes

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.

Gradient forces on double-negative particles in optical tweezers using Bessel beams in the ray optics regime.

Science.gov (United States)

Ambrosio, Leonardo A; Hernández-Figueroa, Hugo E

2010-11-08

Gradient forces on double negative (DNG) spherical dielectric particles are theoretically evaluated for v-th Bessel beams supposing geometrical optics approximations based on momentum transfer. For the first time in the literature, comparisons between these forces for double positive (DPS) and DNG particles are reported. We conclude that, contrary to the conventional case of positive refractive index, the gradient forces acting on a DNG particle may not reverse sign when the relative refractive index n goes from |n|>1 to |n|<1, thus revealing new and interesting trapping properties.

Effect of particle size distribution on permeability in the randomly packed porous media

Science.gov (United States)

Markicevic, Bojan

2017-11-01

An answer of how porous medium heterogeneity influences the medium permeability is still inconclusive, where both increase and decrease in the permeability value are reported. A numerical procedure is used to generate a randomly packed porous material consisting of spherical particles. Six different particle size distributions are used including mono-, bi- and three-disperse particles, as well as uniform, normal and log-normal particle size distribution with the maximum to minimum particle size ratio ranging from three to eight for different distributions. In all six cases, the average particle size is kept the same. For all media generated, the stochastic homogeneity is checked from distribution of three coordinates of particle centers, where uniform distribution of x-, y- and z- positions is found. The medium surface area remains essentially constant except for bi-modal distribution in which medium area decreases, while no changes in the porosity are observed (around 0.36). The fluid flow is solved in such domain, and after checking for the pressure axial linearity, the permeability is calculated from the Darcy law. The permeability comparison reveals that the permeability of the mono-disperse medium is smallest, and the permeability of all poly-disperse samples is less than ten percent higher. For bi-modal particles, the permeability is for a quarter higher compared to the other media which can be explained by volumetric contribution of larger particles and larger passages for fluid flow to take place.

Observations of the vertical concentrations of aerosol particles in the boundary layer by means of tethered balloon method

Energy Technology Data Exchange (ETDEWEB)

Ishioka, Futoshi; Lee, D.I; Taniguchi, Takashi; Kikuchi,Katsuhiro

1988-09-30

In general, it is difficult to accurately understand the behavior of aerosol particles in the boundary layer above urban areas because aerosol sources are influenced by time-dependent factors and local climate. To overcome this difficulty, a particle counter which can count Mie particles with diameters of 0.3 /mu/m or more in five diameter ranges was installed on a large tehered balloon. With this method, the vertical distribution of aerosol concentration was measured in several areas different in meteorological condition, and the dependence of the particle behavior on particle diameter was studied. As a result, it has been revealed that the results of the observations explained above agree with the results of studies conducted in the past, but that dependence on particle diameter is not significant. 37 references, 21 figures, 1 table.

Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth

Directory of Open Access Journals (Sweden)

Z. Wu

2013-07-01

Full Text Available This study examines the hygroscopicity of newly formed particles (diameters range 25–45 nm during two atmospheric new particle formation (NPF events in the German mid-level mountains during the Hill Cap Cloud Thuringia 2010 (HCCT-2010 field experiment. At the end of the NPF event involving clear particle growth, we measured an unusually high soluble particle fraction of 58.5% at 45 nm particle size. The particle growth rate contributed through sulfuric acid condensation only accounts for around 6.5% of the observed growth rate. Estimations showed that sulfuric acid condensation explained, however, only around 10% of that soluble particle fraction. Therefore, the formation of additional water-soluble matter appears imperative to explain the missing soluble fraction. Although direct evidence is missing, we consider water-soluble organics as candidates for this mechanism. For the case with clear growth process, the particle growth rate was determined by two alternative methods based on tracking the mode diameter of the nucleation mode. The mean particle growth rate obtained from the inter-site data comparison using Lagrangian consideration is 3.8 (± 2.6 nm h−1. During the same period, the growth rate calculated based on one site data is 5.0 nm h−1 using log-normal distribution function method. In light of the fact that considerable uncertainties could be involved in both methods, we consider both estimated growth rates consistent.

Correcting for particle size effects on plasma actuator particle image velocimetry measurements

Science.gov (United States)

Masati, A.; Sedwick, R. J.

2018-01-01

Particle image velocimetry (PIV) is often used to characterize plasma actuator flow, but particle charging effects are rarely taken into account. A parametric study was conducted to determine the effects of particle size on the velocity results of plasma actuator PIV experiments. Results showed that smaller particles more closely match air flow velocities than larger particles. The measurement uncertainty was quantified by deconvolving the particle image diameter from the correlation diameter. The true air velocity was calculated by linearly extrapolating to the zero-size particle diameter.

Distinctive signatures for new particles in e/sup +/e/sup -/ annihilation and Z-decay

International Nuclear Information System (INIS)

Tung, W.K.; Kitazawa, Y.

1986-01-01

New particles and new interactions reveal themselves most clearly where standard model contributions are negligibly small. A prominent example with this advantage is the one-lepton inclusive longitudinal structure function (W/sub L/) in e/sup +/e/sup -/ annihilation and Z-decay. The authors discuss general features of this approach and present structure functions for four types of new particles (heavy charged fermion (e.g., new sequential lepton or top quark); heavy neutral lepton; and supersymmetric scalar lepton, i.e. slepton), along with the (small) standard model 'background'. The x-dependence of W/sub L/ provides a distinct signature of the identity of the new particle. Extensions of this approach are discussed

Growth Processes of Particles up to Nanometer in High-Frequency SiH4 Plasmas

International Nuclear Information System (INIS)

Watanabe, Y.; Shiratani, M.; Fukuzawa, T.; Koga, K.

2000-01-01

Growth processes of particles in high-frequency SiH 4 discharges have been understood fairly well in a size range above 10 nm. Recently, we have developed two in situ particle detection methods to study those of particles (clusters) in a size range below ∼ 10 nm. The studies have clarified time evolution of their density and size and revealed the following facts: the cluster density amounts to ∼ 10 11 cm -3 under the device quality low-power and low-pressure conditions: the discharge modulation, substrate heating and H 2 dilution are quite effective in suppressing the cluster growth. We have proposed the cluster growth model explaining reasonably the obtained results. (author)

Selecting the swimming mechanisms of colloidal particles: bubble propulsion versus self-diffusiophoresis.

Science.gov (United States)

Wang, Sijia; Wu, Ning

2014-04-01

Bubble propulsion and self-diffusiophoresis are two common mechanisms that can drive autonomous motion of microparticles in hydrogen peroxide. Although microtubular particles, when coated with platinum in their interior concave surfaces, can propel due to the formation and release of bubbles from one end, the convex Janus particles usually do not generate any visible bubble. They move primarily due to the self-diffusiophoresis. Coincidentally, the platinum films on those particles were typically coated by physical evaporation. In this paper, we use a simple chemical deposition method to make platinum-polystyrene Janus dimers. Surprisingly, those particles are propelled by periodic growth and collapse of bubbles on the platinum-coated lobes. We find that both high catalytic activity and rough surface are necessary to change the propulsion mode from self-diffusiophoresis to bubble propulsion. Our Janus dimers, with combined geometric and interfacial anisotropy, also exhibit distinctive motions at the respective stages of bubble growth and collapse, which differ by 5-6 orders of magnitude in time. Our study not only provides insight into the link between self-diffusiophoresis and bubble propulsion but also reveals the intriguing impacts of the combined geometric and interfacial anisotropy on self-propulsion of particles.

Environmental radiation safety: plutonium/soil interactions for plutonium particles in soil

International Nuclear Information System (INIS)

Moss, O.R.; Rossingnol, E.J.; Cannon, W.C.; Stevens, D.L.

1980-12-01

The goal of this project is to provide information useful in estimating hazards related to resuspension characteristics and subsequent aerodynamic behavior of aerosols from a mixing of soil and 238 PuO 2 . Experiments were carried out to determine whether simple models, used to predict the total activity concentration of resuspended particles, need to be modified to account for changes in the 238 PuO 2 activity distribution on resuspended particles due to aging of the soil mixture under humid or dry conditions. A literature search revealed that one model, based on the suspension factors, S/sub f/, may be a useful predictor of hazard reduction irrespective of site. Our experiments demonstrated little or no change in the activity of resuspended particles following humid or dry aging of the soil- 238 PuO 2 mixture. Additional terms for activity distribution changes should not be needed for the simple resuspension hazard model

Cross-Sectional Information on Pore Structure and Element Distribution of Sediment Particles by SEM and EDS

Directory of Open Access Journals (Sweden)

Minghong Chen

2017-01-01

Full Text Available The interaction between pollutants and sediment particles often occurs on the particle surface, so surface properties directly affect surface reaction. The physical and chemical processes occurring on sediment particle surfaces are microscopic processes and as such need to be studied from a microscopic perspective. In this study, field emission scanning electron microscopy (SEM and energy dispersive X-ray spectrometer (EDS were adopted to observe and analyze the pore structure and element distribution of sediment particles. In particular, a special method of sample preparation was used to achieve the corresponding cross-sectional information of sediment particles. Clear images of a particle profile and pore microstructure were obtained by high-resolution SEM, while element distribution maps of sediment particles were obtained by EDS. The results provide an intuitive understanding of the internal microenvironment and external behavior of sediment particles, in addition to revealing a significant role of pore microstructure in the adsorption and desorption of pollutants. Thus, a combination of different experimental instruments and observation methods can provide real images and information on microscopic pore structure and element distribution of sediment particles. These results should help to improve our understanding of sediment dynamics and its environmental effects.

Effects of Initial Particle Distribution on an Energetic Dispersal of Particles

Science.gov (United States)

Rollin, Bertrand; Ouellet, Frederick; Koneru, Rahul; Garno, Joshua; Durant, Bradford

2017-11-01

Accurate predictions of the late time solid particle cloud distribution ensuing an explosive dispersal of particles is an extremely challenging problem for compressible multiphase flow simulations. The source of this difficulty is twofold: (i) The complex sequence of events taking place. Indeed, as the blast wave crosses the surrounding layer of particles, compaction occurs shortly before particles disperse radially at high speed. Then, during the dispersion phase, complex multiphase interactions occurs between particles and detonation products. (ii) Precise characterization of the explosive and particle distribution is virtually impossible. In this numerical experiment, we focus on the sensitivity of late time particle cloud distributions relative to carefully designed initial distributions, assuming the explosive is well described. Using point particle simulations, we study the case of a bed of glass particles surrounding an explosive. Constraining our simulations to relatively low initial volume fractions to prevent reaching of the close packing limit, we seek to describe qualitatively and quantitatively the late time dependency of a solid particle cloud on its distribution before the energy release of an explosive. This work was supported by the U.S. DoE, NNSA, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Sub-micrometer refractory carbonaceous particles in the polar stratosphere

Directory of Open Access Journals (Sweden)

K. Schütze

2017-10-01

Full Text Available Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM combined with energy-dispersive X-ray microanalysis. A total of 4202 particles (TEM  =  3872; SEM  =  330 were analyzed from these samples, which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. Particles that were volatile in the microscope beams contained ammonium sulfates and hydrogen sulfates and dominated the samples. Some particles with diameters ranging from 20 to 830 nm were refractory in the electron beams. Carbonaceous particles containing additional elements to C and O comprised from 72 to 100 % of the refractory particles. The rest were internal mixtures of these materials with sulfates. The median number mixing ratio of the refractory particles, expressed in units of particles per milligram of air, was 1.1 (mg air−1 and varied between 0.65 and 2.3 (mg air−1. Most of the refractory carbonaceous particles are completely amorphous, a few of the particles are partly ordered with a graphene sheet separation distance of 0.37 ± 0.06 nm (mean value ± standard deviation. Carbon and oxygen are the only detected major elements with an atomic O∕C ratio of 0.11 ± 0.07. Minor elements observed include Si, S, Fe, Cr and Ni with the following atomic ratios relative to C: Si∕C: 0.010 ± 0.011; S∕C: 0.0007 ± 0.0015; Fe∕C: 0.0052 ± 0.0074; Cr∕C: 0.0012 ± 0.0017; Ni∕C: 0.0006 ± 0.0011 (all mean values ± standard deviation.High-resolution element distribution images reveal that the minor elements are distributed within the carbonaceous matrix; i.e., heterogeneous inclusions are not observed. No difference in size, nanostructure and elemental composition was found between

Magnetic field-aligned particle precipitation

International Nuclear Information System (INIS)

Carlson, W.

1985-01-01

Magnetic field-aligned particle fluxes are a common auroral phenomenon. Precipitating field-aligned electrons are seen in the vicinity of auroral arcs as suprathermal bursts, as well as superimposed on the more isotropic inverted V electron precipitation. Electron distribution functions reveal two distinct source populations for the inverted V and field-aligned electron components, and also suggest possible acceleration mechanisms. The inverted V electrons are a hot, boundary plasma sheet population that gains the full parallel acceleration. The field-aligned component appears to originate from cold ionospheric electrons that may be distributed throughout the acceleration region. A turbulent parallel field might explain the apparent lifetime of cold electrons in the acceleration region

Reverse Transcriptase-Containing Particles Induced in Rous Sarcoma Virus-Transformed Rat Cells by Arginine Deprivation

Science.gov (United States)

Kotler, Moshe; Weinberg, Eynat; Haspel, Osnat; Becker, Yechiel

1972-01-01

Incubation of rat cells transformed by Rous sarcoma virus (RSV) in an arginine-deficient medium resulted in accumulation of particles in the culture medium. Such particles did not appear when the transformed rat cells were incubated in a complete medium nor in the medium of primary rat cells which were incubated either in arginine-deficient or complete media. The particles which were released from the arginine-deprived transformed rat cells resemble C-type particles in their properties. These particles band in sucrose gradients at a density of 1.16 g/ml and contain 35S ribonucleic acid (RNA) molecules and a reverse transcriptase activity. Analysis of the cytoplasm of transformed and primary rat cells, deprived and undeprived of arginine, revealed the presence of reverse transcriptase-containing particles which banded in sucrose gradients at a density of 1.14 g/ml. These particles differed from the particles released into the medium by the arginine-deprived RSV-transformed rat cells. The deoxyribonucleic acid (DNA) molecules synthesized in vitro by the reverse transcriptase present in the particles isolated from the medium of arginine-deprived cells hybridized to RSV RNA, whereas the DNA synthesized by the cell-bound enzyme had no homology to RSV RNA. PMID:4116137

Transcriptome Profiling of the Lungs Reveals Molecular Clock Genes Expression Changes after Chronic Exposure to Ambient Air Particles

Directory of Open Access Journals (Sweden)

Pengcheng Song

2017-01-01

Full Text Available The symptoms of asthma, breathlessness, insomnia, etc. all have relevance to pulmonary rhythmic disturbances. Epidemiology and toxicology studies have demonstrated that exposure to ambient air particles can result in pulmonary dysfunction. However, there are no data directly supporting a link between air pollution and circadian rhythm disorder. In the present study, we found that breathing highly polluted air resulted in changes of the molecular clock genes expression in lung by transcriptome profiling analyses in a rodent model. Compared to those exposed to filtered air, in both pregnant and offspring rats in the unfiltered group, key clock genes (Per1, Per2, Per3, Rev-erbα and Dbp expression level decreased and Bmal1 expression level increased. In both rat dams and their offspring, after continuous exposure to unfiltered air, we observed significant histologic evidence for both perivascular and peribronchial inflammation, increased tissue and systemic oxidative stress in the lungs. Our results suggest that chronic exposure to particulate matter can induce alterations of clock genes expression, which could be another important pathway for explaining the feedbacks of ambient particle exposure in addition to oxidative stress and inflammation.

Strange particles

International Nuclear Information System (INIS)

Chinowsky, W.

1989-01-01

Work done in the mid 1950s at Brookhaven National Laboratory on strange particles is described. Experiments were done on the Cosmotron. The author describes his own and others' work on neutral kaons, lambda and theta particles and points out the theoretical gap between predictions and experimental findings. By the end of the decade, the theory of strange particles was better understood. (UK)

Particle and particle systems characterization small-angle scattering (SAS) applications

CERN Document Server

Gille, Wilfried

2016-01-01

Small-angle scattering (SAS) is the premier technique for the characterization of disordered nanoscale particle ensembles. SAS is produced by the particle as a whole and does not depend in any way on the internal crystal structure of the particle. Since the first applications of X-ray scattering in the 1930s, SAS has developed into a standard method in the field of materials science. SAS is a non-destructive method and can be directly applied for solid and liquid samples. Particle and Particle Systems Characterization: Small-Angle Scattering (SAS) Applications is geared to any scientist who might want to apply SAS to study tightly packed particle ensembles using elements of stochastic geometry. After completing the book, the reader should be able to demonstrate detailed knowledge of the application of SAS for the characterization of physical and chemical materials.

Specific activity of uranium and thorium in marketable rock phosphate as a function of particle size

Energy Technology Data Exchange (ETDEWEB)

Metzger, R; McKlveen, J W [Arizona State Univ., Tempe (USA); Jenkins, R [Phillip Morris Research Center, Richmond, VA (USA); McDowell, W J [Oak Ridge National Lab., TN (USA)

1980-07-01

Marketable rock phosphate fertilizer from Florida was classified into seven particle size fractions ranging from 149 ..mu..m to less than 0.5 ..mu..m using a Bahco Microparticle Classifier and air elutriation. The resulting size fractions were assayed for U and /sup 230/Th by solvent extraction and liquid scintillation ..cap alpha..-spectroscopy. Results indicated that the specific activity of U and /sup 230/Th increased with decreasing particle size. Maximum activities of 110 pCi/g U and 50 pCi/g /sup 230/Th were found in particles less than 1.0 ..mu..m in aerodynamic diameter. Qualitative emission spectrographic analysis of the fractions revealed that the concentrations of Al, Cu, Mg, Na, Ti and Zn also increased with decreasing particle size.

The influence of magnetic field on the inertial deposition of a particle on a rotating disk

International Nuclear Information System (INIS)

Tsatsin, P O; Beskachko, V P

2008-01-01

The problem of inertial deposition attracts considerable attention in the connection with the separating of detrimental impurities and the refining of liquid metals. In the present investigation the deposition of particles suspended in a conducting melt on the rotating disk in the presence of axial uniform magnetic field is considered. The field of the fluid velocities is computed by means of the MHD-analogue of Karman reduction, which makes possible to reduce initial governing nonlinear partial differential equations to a two-point boundary value problem for the set of ordinary differential equations. The influence of magnetic field on dia-and paramagnetic particle deposition effect was estimated. The results reveal that magnetic field has significant effect on particle parameters, especially for magnetic particles

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.

October 1972 solar event: The third dimension in solar particle propagation

International Nuclear Information System (INIS)

Domingo, V.; Page, D.E.; Wenzel, K.

1976-01-01

From late on October 29 until November 3, 1972, our experiment on the European Space Research Organization satellite Heos 2 recorded the arrival of an enhanced interplanetary particle intensity. A dramatic 'slot' in count rate and other sudden anisotropy and flux changes (measured in and perpendicular to the ecliptic plane) were found to coincide with changes in the theta (north-south) ecliptic direction of the interplanetary magnetic field. However, reorientation of strongly field-aligned particle distributions relative to the detectors was insufficient to explain the intensity changes recorded, and the conclusion had to be drawn that the spacecraft was repeatedly crossing a boundary between one regime and a neighboring one with a different particle population. Since the switching from one regime to the other continued for several days, it would seem reasonable to suggest that the boundary between regimes was roughly parallel to the ecliptic plane. This idea was reinforced by the discovery that each time that the particle regime changed, not only did B/sub theta/ change, but the solar wind flow direction changed, the dip angle reversing sign. It would thus appear that when the solar wind blows three-dimensional snakelike tubes in interplanetary space, MeV particles obediently follow the field line bundles within such tubes and experience considerable difficulty in crossing from one tube to a neighboring tube which encloses a different regime. Because of the absence of cross-field particle movement, measurements made at higher solar latitudes, where most solar active regions occur, could reveal a somewhat different picture of the development of solar particle events

Exploring the tensile strain energy absorption of hybrid modified epoxies containing soft particles

International Nuclear Information System (INIS)

Abadyan, M.; Bagheri, R.; Kouchakzadeh, M.A.; Hosseini Kordkheili, S.A.

2011-01-01

Research highlights: → Two epoxy systems have been modified by combination of fine and coarse modifiers. → While both hybrid systems reveal synergistic K IC , no synergism is observed in tensile test. → It is found that coarse particles induce stress concentration in hybrid samples. → Stress concentration leads to fracture of samples at lower energy absorption levels. -- Abstract: In this paper, tensile strain energy absorption of two different hybrid modified epoxies has been systematically investigated. In one system, epoxy has been modified by amine-terminated butadiene acrylonitrile (ATBN) and hollow glass spheres as fine and coarse modifiers, respectively. The other hybrid epoxy has been modified by the combination of ATBN and recycled Tire particles. The results of fracture toughness measurement of blends revealed synergistic toughening for both hybrid systems in some formulations. However, no evidence of synergism is observed in tensile test of hybrid samples. Scanning electron microscope (SEM), transmission optical microscope (TOM) and finite element (FEM) simulation were utilized to study deformation mechanisms of hybrid systems in tensile test. It is found that coarse particles induce stress concentration in hybrid samples. This produces non-uniform strain localized regions which lead to fracture of hybrid samples at lower tensile loading and energy absorption levels.

Aerosol particle mixing state, refractory particle number size distributions and emission factors in a polluted urban environment: Case study of Metro Manila, Philippines

Science.gov (United States)

Kecorius, Simonas; Madueño, Leizel; Vallar, Edgar; Alas, Honey; Betito, Grace; Birmili, Wolfram; Cambaliza, Maria Obiminda; Catipay, Grethyl; Gonzaga-Cayetano, Mylene; Galvez, Maria Cecilia; Lorenzo, Genie; Müller, Thomas; Simpas, James B.; Tamayo, Everlyn Gayle; Wiedensohler, Alfred

2017-12-01

studies reported such high number concentration of ultrafine refractory particles under ambient conditions. Inverse modeling of emission factors of refractory particle number size distributions revealed that diesel-fed public utility Jeepneys, commonly used for public transportation, are responsible for 94% of total roadside emitted refractory particle mass. The observed results showed that the majority of urban pollution in Metro Manila is dominated by carbonaceous aerosol. This suggests that PM10 or PM2.5 metrics do not fully describe possible health related effects in this kind of urban environments. Extremely high concentrations of ultrafine particles have been and will continue to induce adverse health related effects, because of their potential toxicity. We imply that in megacities, where the major fraction of particulates originates from the transport sector, PM10 or PM2.5 mass concentration should be complemented by legislative measurements of equivalent black carbon mass concentration.

Particle accelerator

International Nuclear Information System (INIS)

Ress, R.I.

1976-01-01

Charged particles are entrained in a predetermined direction, independent of their polarity, in a circular orbit by a magnetic field rotating at high speed about an axis in a closed cylindrical or toroidal vessel. The field may be generated by a cylindrical laser structure, whose beam is polygonally reflected from the walls of an excited cavity centered on the axis, or by high-frequency energization of a set of electromagnets perpendicular to the axis. In the latter case, a separate magnetostatic axial field limits the orbital radius of the particles. These rotating and stationary magnetic fields may be generated centrally or by individual magnets peripherally spaced along its circular orbit. Chemical or nuclear reactions can be induced by collisions between the orbiting particles and an injected reactant, or by diverting high-speed particles from one doughnut into the path of counterrotating particles in an adjoining doughnut

Flow regime and deposition pattern of evaporating binary mixture droplet suspended with particles.

Science.gov (United States)

Zhong, Xin; Duan, Fei

2016-02-01

The flow regimes and the deposition pattern have been investigated by changing the ethanol concentration in a water-based binary mixture droplet suspended with alumina nanoparticles. To visualize the flow patterns, Particle Image Velocimetry (PIV) has been applied in the binary liquid droplet containing the fluorescent microspheres. Three distinct flow regimes have been revealed in the evaporation. In Regime I, the vortices and chaotic flows are found to carry the particles to the liquid-vapor interface and to promote the formation of particle aggregation. The aggregates move inwards in Regime II as induced by the Marangoni flow along the droplet free surface. Regime III is dominated by the drying of the left water and the capillary flow driving particles radially outward is observed. The relative weightings of Regimes I and II, which are enhanced with an increasing load of ethanol, determine the motion of the nanoparticles and the formation of the final drying pattern.

Metallorganic routes to nanoscale iron and titanium oxide particles encapsulated in mesoporous alumina: formation, physical properties, and chemical reactivity.

Science.gov (United States)

Schneider, J J; Czap, N; Hagen, J; Engstler, J; Ensling, J; Gütlich, P; Reinoehl, U; Bertagnolli, H; Luis, F; de Jongh, L J; Wark, M; Grubert, G; Hornyak, G L; Zanoni, R

2000-12-01

Iron and titanium oxide nanoparticles have been synthesized in parallel mesopores of alumina by a novel organometallic "chimie douce" approach that uses bis(toluene)iron(0) (1) and bis(toluene)titanium(0) (2) as precursors. These complexes are molecular sources of iron and titanium in a zerovalent atomic state. In the case of 1, core shell iron/iron oxide particles with a strong magnetic coupling between both components, as revealed by magnetic measurements, are formed. Mössbauer data reveal superparamagnetic particle behavior with a distinct particle size distribution that confirms the magnetic measurements. The dependence of the Mössbauer spectra on temperature and particle size is explained by the influence of superparamagnetic relaxation effects. The coexistence of a paramagnetic doublet and a magnetically split component in the spectra is further explained by a distribution in particle size. From Mössbauer parameters the oxide phase can be identified as low-crystallinity ferrihydrite oxide. In agreement with quantum size effects observed in UV-visible studies, TEM measurements determine the size of the particles in the range 5-8 nm. The particles are mainly arranged alongside the pore walls of the alumina template. TiO2 nanoparticles are formed by depositing 2 in mesoporous alumina template. This produces metallic Ti, which is subsequently oxidized to TiO2 (anatase) within the alumina pores. UV-visible studies show a strong quantum confinement effect for these particles. From UV-visible investigations the particle size is determined to be around 2 nm. XPS analysis of the iron- and titania- embedded nanoparticles reveal the presence of Fe2O3 and TiO2 according to experimental binding energies and the experimental line shapes. Ti4+ and Fe3+ are the only oxidation states of the particles which can be determined by this technique. Hydrogen reduction of the iron/iron-oxide nanoparticles at 500 degrees C under flowing H2/N2 produces a catalyst, which is active

Self-Assembly of DNA-Coated Particles: Experiment, Simulation and Theory

Science.gov (United States)

Song, Minseok

complementary ssDNA functionality on individual particles ('multi-flavoring') as opposed to functionalization of particles with the same type of ssDNA ('uni-flavoring') is explored as a possible design handle for tuning interparticle interactions and, thereby, accessing diverse structures. We employ a combination of simulations, theory, and experimental validation toward establishing 'multi-flavoring' as a rational design strategy. Firstly, MD simulations are carried out using effective pair potentials to describe interparticle interactions that are representative of different degrees of ssDNA 'multi-flavoring'. These simulations reveal the template-free assembly of a diversity of 2D crystal polymorphs that is apparently tunable by controlling the relative attractive strengths between like and unlike functionalized particles. The resulting phase diagrams predict conditions (i.e., strengths of relative interparticle interactions) for obtaining crystalline phases with lattice symmetries ranging among square, alternating string hexagonal, random hexagonal, rhombic, honeycomb, and even kagome. Finally, these model findings are translated to experiments, in which binary microparticles are decorated with a tailored mixture of two different complementary ssDNA strands as a straight-forward means to realize tunable particle interactions. Guided by simple statistical mechanics and the detailed MD simulations, 'multi-flavoring' and control of solution phase particle stoichiometry resulted in experimental realization of structurally diverse 2D microparticle assemblies consistent with predictions, such as square, pentagonal and hexagonal lattices (honeycomb, kagome). The combined simulation, theory, and experimental findings reveal how control of interparticle interactions via DNA-functionalized particle "multi-flavoring" can lead to an even wider range of accessible colloidal crystal structures. The 2D experiments coupled with the model predictions may be used to provide new fundamental

Particle transport in 3He-rich events: wave-particle interactions and particle anisotropy measurements

Directory of Open Access Journals (Sweden)

B. T. Tsurutani

2002-04-01

Full Text Available Energetic particles and MHD waves are studied using simultaneous ISEE-3 data to investigate particle propagation and scattering between the source near the Sun and 1 AU. 3 He-rich events are of particular interest because they are typically low intensity "scatter-free" events. The largest solar proton events are of interest because they have been postulated to generate their own waves through beam instabilities. For 3 He-rich events, simultaneous interplanetary magnetic spectra are measured. The intensity of the interplanetary "fossil" turbulence through which the particles have traversed is found to be at the "quiet" to "intermediate" level of IMF activity. Pitch angle scattering rates and the corresponding particle mean free paths lW - P are calculated using the measured wave intensities, polarizations, and k directions. The values of lW - P are found to be ~ 5 times less than the value of lHe , the latter derived from He intensity and anisotropy time profiles. It is demonstrated by computer simulation that scattering rates through a 90° pitch angle are lower than that of other pitch angles, and that this is a possible explanation for the discrepancy between the lW - P and lHe values. At this time the scattering mechanism(s is unknown. We suggest a means where a direct comparison between the two l values could be made. Computer simulations indicate that although scattering through 90° is lower, it still occurs. Possibilities are either large pitch angle scattering through resonant interactions, or particle mirroring off of field compression regions. The largest solar proton events are analyzed to investigate the possibilities of local wave generation at 1 AU. In accordance with the results of a previous calculation (Gary et al., 1985 of beam stability, proton beams at 1 AU are found to be marginally stable. No evidence for substantial wave amplitude was found. Locally generated waves, if present, were less than 10-3 nT 2 Hz-1 at the leading

Particle transport in 3He-rich events: wave-particle interactions and particle anisotropy measurements

Directory of Open Access Journals (Sweden)

T. Hada

Full Text Available Energetic particles and MHD waves are studied using simultaneous ISEE-3 data to investigate particle propagation and scattering between the source near the Sun and 1 AU. 3 He-rich events are of particular interest because they are typically low intensity "scatter-free" events. The largest solar proton events are of interest because they have been postulated to generate their own waves through beam instabilities. For 3 He-rich events, simultaneous interplanetary magnetic spectra are measured. The intensity of the interplanetary "fossil" turbulence through which the particles have traversed is found to be at the "quiet" to "intermediate" level of IMF activity. Pitch angle scattering rates and the corresponding particle mean free paths lW - P are calculated using the measured wave intensities, polarizations, and k directions. The values of lW - P are found to be ~ 5 times less than the value of lHe , the latter derived from He intensity and anisotropy time profiles. It is demonstrated by computer simulation that scattering rates through a 90° pitch angle are lower than that of other pitch angles, and that this is a possible explanation for the discrepancy between the lW - P and lHe values. At this time the scattering mechanism(s is unknown. We suggest a means where a direct comparison between the two l values could be made. Computer simulations indicate that although scattering through 90° is lower, it still occurs. Possibilities are either large pitch angle scattering through resonant interactions, or particle mirroring off of field compression regions. The largest solar proton events are analyzed to investigate the possibilities of local wave generation at 1 AU. In accordance with the results of a previous calculation (Gary et al., 1985 of beam stability, proton beams at 1 AU are found to be marginally stable. No evidence for substantial wave amplitude was found. Locally generated waves, if present, were less than 10-3 nT 2 Hz-1 at the leading

Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

Science.gov (United States)

Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

2003-03-01

Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

Influence of nanoclay particles modification by polyester-amide hyperbranched polymer on the corrosion protective performance of the epoxy nanocomposite

International Nuclear Information System (INIS)

Ganjaee Sari, M.; Ramezanzadeh, B.; Shahbazi, M.; Pakdel, A.S.

2015-01-01

Highlights: • Nanoclay particles were modified with polyester-amide hyperbranched polymer. • Epoxy/clay nanocomposites were prepared using modified clay particles. • Surface modification enhanced the clay particles exfoliation properties. • Surface modified clay particles enhanced corrosion resistance of the epoxy coating. - Abstract: Surface modification of nanoclay particles was carried out by various amounts of polyester-amide hyperbranched polymer (HBP). Thermal gravimetric analysis and X-ray diffraction analysis were performed to estimate the efficiency of the HPB grafting on the clay particles. Epoxy/clay nanocomposites were prepared by addition of 1 wt.% unmodified and modified clays. The corrosion protection properties of the nanocomposites were evaluated by electrochemical impedance spectroscopy (EIS). Results revealed that surface modification of the clay particles by HBP caused significant enhancement of the epoxy coating corrosion resistance especially when the ‘polymer/clay’ ratios were 10/1 and 5/1

Observation of Individual Particle Morphology, Mineralogy in tandem with Columnar Spectral Aerosol Optics: A Summertime Study over North western India

Science.gov (United States)

Mishra, S.; Saha, N.; Singh, S.; Agnihotri, R.; Sharma, C.; Prasad, M. V. S. N.; Arya, B. C.; Naaraayanan, T.; Gautam, S.; Rathore, J. S.; Soni, V. K.; Tawale, J. S.

2014-12-01

Limitation over region specific data on dust morphology (particle shape, size) and mineralogy gives rise to uncertainty in estimation of optical and radiative properties of mineral dust (Mishra and Tripathi, 2008; Mishra et al., 2008). To address this issue over Indian arid zone (local source of mineral dust), a short field campaign was organized in Jodhpur, located in Rajasthan, a north western state of India, over seven sites (four in city and three far from city) with varying altitudes in June 2013. Jodhpur lies in vicinity of the Thar Desert of Rajasthan. Particles were collected on pure Tin substrates for individual particle morphological and elemental composition analysis using Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectrometer (EDS). The morphological parameters (e.g. Aspect ratio; AR, Circulatory parameter; CIR.) were retrieved following Okada et al. (2001) using Image J software. Columnar spectral aerosol optical thickness has been measured by Microtops-II sun photometer for a set of five wavelengths (380 to 1020 nm) over all the sites in tandem with regional aerosol collection. SEM analysis reveals that the particles close to spherical shape (AR range 1.0-1.2) were found to be ~ 18% whereas particles with AR range 1.2-1.4 were found to be abundant (25%) followed with that of AR range 1.4-1.6 and 1.6-1.8 (each ~ 17%) and 1.8-2.0 (~ 14%) while the particles with AR >2 (highly non-spherical) were found to be ~ 8%. Here, it is noteworthy to mention that AR=1 for spherical particle while increasing AR (>1) exhibit increasing non-sphericity of particles. The EDS analysis reveals that 43% particles were observed with low hematite (H ≤ 1%; volume percentage), 24% (H 1-2 %), 14% (H 2-3%), 5% (H 3-4%) and 14% (H >4%). The aforementioned proportions will be extremely useful for simulating the optical and radiative properties of regional aerosols. From the Microtops-II observations, Ångström exponent for spectral interval of 380 to

Optimization and Characterization of Magnetic Nano Particle - Vesicular Stomatitis Virus complexes for Therapy of Hepatocellular Carcinoma

OpenAIRE

Wille, Florian

2017-01-01

This thesis describes the complex formation of oncolytic viral particles (VSV) and magnetic nanoparticles (MNP). Surface decoration of the complexes with hyaluronic acid resulted in reduced antibody mediated inactivation in vitro and prolonged circulation time in vivo. First in vivo results of intra-tumoral complex application in HCC bearing rats revealed a higher viral titer compared to naked VSV particles and the ability to visualize these complexes by MRI. Diese Arbeit beschreibt die K...

Comparative In Vitro Biological Toxicity of Four Kinds of Air Pollution Particles.

Science.gov (United States)

Shin, Han-Jae; Cho, Hyun Gi; Park, Chang Kyun; Park, Ki Hong; Lim, Heung Bin

2017-10-01

Accumulating epidemiological evidence indicates that exposure to fine air pollution particles (APPs) is associated with a variety of adverse health effects. However, the exact physiochemical properties and biological toxicities of fine APPs are still not well characterized. We collected four types of fine particle (FP) (diesel exhaust particles [DEPs], natural organic combustion [NOC] ash, synthetic organic combustion [SOC] ash, and yellow sand dust [YSD]) and investigated their physicochemical properties and in vitro biological toxicity. DEPs were almost entirely composed of ultrafine particles (UFPs), while the NOC, SOC, and YSD particles were a mixture of UFPs and FPs. The main elements in the DEPs, NOC ash, SOC ash, and YSD were black carbon, silicon, black carbon, and silicon, respectively. DEPs exhibited dose-dependent mutagenicity even at a low dose in Salmonella typhimurium TA 98 and 100 strains in an Ames test for genotoxicity. However, NOC, SOC, and YSD particles did not show any mutagenicity at high doses. The neutral red uptake assay to test cell viability revealed that DEPs showed dose-dependent potent cytotoxicity even at a low concentration. The toxicity of DEPs was relatively higher than that of NOC, SOC, and YSD particles. Therefore, these results indicate that among the four FPs, DEPs showed the highest in vitro biological toxicity. Additional comprehensive research studies such as chemical analysis and in vivo acute and chronic inhalation toxicity tests are necessary to determine and clarify the effects of this air contaminant on human health.

Numerical investigation of compaction of deformable particles with bonded-particle model

Directory of Open Access Journals (Sweden)

Dosta Maksym

2017-01-01

Full Text Available In this contribution, a novel approach developed for the microscale modelling of particles which undergo large deformations is presented. The proposed method is based on the bonded-particle model (BPM and multi-stage strategy to adjust material and model parameters. By the BPM, modelled objects are represented as agglomerates which consist of smaller ideally spherical particles and are connected with cylindrical solid bonds. Each bond is considered as a separate object and in each time step the forces and moments acting in them are calculated. The developed approach has been applied to simulate the compaction of elastomeric rubber particles as single particles or in a random packing. To describe the complex mechanical behaviour of the particles, the solid bonds were modelled as ideally elastic beams. The functional parameters of solid bonds as well as material parameters of bonds and primary particles were estimated based on the experimental data for rubber spheres. Obtained results for acting force and for particle deformations during uniaxial compression are in good agreement with experimental data at higher strains.

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...

Facilitation of transscleral drug delivery by drug loaded magnetic polymeric particles.

Science.gov (United States)

Mousavikhamene, Zeynab; Abdekhodaie, Mohammad J; Ahmadieh, Hamid

2017-10-01

A unique method was used to facilitate ocular drug delivery from periocular route by drug loaded magnetic sensitive particles. Injection of particles in periocular space along the eye axis followed by application of magnetic field in front of the eye would trigger the magnetic polymeric particles to move along the direction of magnetic force and reside against the outer surface of the sclera. This technique prevents removal of drug in the periocular space, observed in conventional transscleral drug delivery systems and hence higher amount of drug can enter the eye in a longer period of time. The experiments were performed by fresh human sclera and an experimental setup. Experimental setup was designed by side by side diffusion cell and hydrodynamic and thermal simulation of the posterior segment of the eye were applied. Magnetic polymeric particles were synthesized by alginate as a model polymer, iron oxide nanoparticles as a magnetic agent and diclofenac sodium as a model drug and characterized by SEM, TEM, DLS and FT-IR techniques. According to the SEM images, the size range of particles is around 60 to 800nm. The results revealed that the cumulative drug transfer from magnetic sensitive particles across the sclera improves by 70% in the presence of magnetic field. The results of this research show promising method of drug delivery to use magnetic properties to facilitate drug delivery to the back of the eye. Copyright © 2017. Published by Elsevier B.V.

Effect of particle-particle shearing on the bioleaching of sulfide minerals.

Science.gov (United States)

Chong, N; Karamanev, D G; Margaritis, A

2002-11-05

The biological leaching of sulfide minerals, used for the production of gold, copper, zinc, cobalt, and other metals, is very often carried out in slurry bioreactors, where the shearing between sulfide particles is intensive. In order to be able to improve the efficiency of the bioleaching, it is of significant importance to know the effect of particle shearing on the rate of leaching. The recently proposed concept of ore immobilization allowed us to study the effect of particle shearing on the rate of sulfide (pyrite) leaching by Thiobacillus ferrooxidans. Using this concept, we designed two very similar bioreactors, the main difference between which was the presence and absence of particle-particle shearing. It was shown that when the oxygen mass transfer was not the rate-limiting step, the rate of bioleaching in the frictionless bioreactor was 2.5 times higher than that in a bioreactor with particle friction (shearing). The concentration of free suspended cells in the frictionless bioreactor was by orders of magnitude lower than that in the frictional bioreactor, which showed that particle friction strongly reduces the microbial attachment to sulfide surface, which, in turn, reduces the rate of bioleaching. Surprisingly, it was found that formation of a layer of insoluble iron salts on the surface of sulfide particles is much slower under shearless conditions than in the presence of particle-particle shearing. This was explained by the effect of particle friction on liquid-solid mass transfer rate. The results of this study show that reduction of the particle friction during bioleaching of sulfide minerals can bring important advantages not only by increasing significantly the bioleaching rate, but also by increasing the rate of gas-liquid oxygen mass transfer, reducing the formation of iron precipitates and reducing the energy consumption. One of the efficient methods for reduction of particle friction is ore immobilization in a porous matrix. Copyright 2002

Recent Observations of Energetic Particles from the Voyager Spacecraft

Science.gov (United States)

Cummings, A. C.; Stone, E. C.; Heikkila, B.; Lal, N.; Webber, W. R.

2013-05-01

The Voyager spacecraft have been exploring the heliosheath since their crossings of the solar wind termination shock on December 2004 (Voyager 1) and August 2007 (Voyager 2). Starting on 7 May 2012, dramatic short-term changes in the intensities of heliospheric particles and galactic cosmic rays have been occurring periodically at Voyager 1. In July, a series of encounters with a heliospheric depletion region occurred, culminating on 25 August 2012 with the durable entry into the region by Voyager 1 (durable at least through the time of this writing in early February 2012). This depletion region is characterized by the disappearance of particles accelerated in the heliosphere, the anomalous cosmic rays and termination shock particles, and the increased intensity of galactic cosmic ray nuclei and electrons. The result is that the low-energy part of the galactic cosmic ray spectra is being revealed for the first time. Data from the magnetometer experiment on Voyager 1 implies that the spacecraft is not yet in the interstellar medium, but it apparently has a good connection path to it. At Voyager 2, dramatic changes haven't occurred but there are longer-term trends in the intensities that are different from what were observed on Voyager 1. We will report on the recent observations of energetic particles from both spacecraft. This work was supported by NASA under contract NNN12AA012.

Dynamics of a particle attracted by a magnetized wire

International Nuclear Information System (INIS)

Lawson, W.F. Jr.; Simons, W.H.; Treat, R.P.

1977-01-01

The dynamics of a particle attracted by a magnetized wire is studied for nonvanishing gravitational forces and a broad range of Stokes number K. The Newtonian equation of motion for the particle is integrated for 10 -2 2 , a range which includes conditions where the particle inertia cannot be ignored. Families of trajectories, typical of low and high K, reveal the dominance of viscous forces at low K, as expected, and show oscillatory approach to capture for high K, where inertia is significant. Capture distances in the interval 1< or =X/sub c/< or =8 are given as a function of three independent dimensionless parameters which measure the strengths of the magnetic, viscous, and gravitational forces. The range of conditions is established for which it is permissible to neglect, for the purpose of computing capture distances, both the inertia and the radially attractive short-range part of the magnetic force. The equation of motion in which the inertia and the short-range term are neglected is studied. An integral of this equation is found which extends the trajectory equations of Zebel and Luborsky to include the gravitational force. A general approach to the construction of the integral of motion shows how to find the trajectory equation for a particle moving in a more complicated incompressible viscous flow with higher multipole contributions to the magnetic field of force

Is an elementary particle really: (i) a particle? (ii) elementary?

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Is an elementary particle really: (i) a particle? (ii) elementary? Over centuries, naïve notions about this have turned out incorrect. Particles are not really pointlike. The word elementary is not necessarily well-defined. Notes:

A Hybrid Chaos-Particle Swarm Optimization Algorithm for the Vehicle Routing Problem with Time Window

Directory of Open Access Journals (Sweden)

Qi Hu

2013-04-01

Full Text Available State-of-the-art heuristic algorithms to solve the vehicle routing problem with time windows (VRPTW usually present slow speeds during the early iterations and easily fall into local optimal solutions. Focusing on solving the above problems, this paper analyzes the particle encoding and decoding strategy of the particle swarm optimization algorithm, the construction of the vehicle route and the judgment of the local optimal solution. Based on these, a hybrid chaos-particle swarm optimization algorithm (HPSO is proposed to solve VRPTW. The chaos algorithm is employed to re-initialize the particle swarm. An efficient insertion heuristic algorithm is also proposed to build the valid vehicle route in the particle decoding process. A particle swarm premature convergence judgment mechanism is formulated and combined with the chaos algorithm and Gaussian mutation into HPSO when the particle swarm falls into the local convergence. Extensive experiments are carried out to test the parameter settings in the insertion heuristic algorithm and to evaluate that they are corresponding to the data’s real-distribution in the concrete problem. It is also revealed that the HPSO achieves a better performance than the other state-of-the-art algorithms on solving VRPTW.

Fission Product Release Behavior of Individual Coated Fuel Particles for High-Temperature Gas-Cooled Reactors

Energy Technology Data Exchange (ETDEWEB)

Minato, Kazuo [Japan Atomic Energy Research Institute (Japan); Sawa, Kazuhiro [Japan Atomic Energy Research Institute (Japan); Koya, Toshio [Japan Atomic Energy Research Institute (Japan); Tomita, Takeshi [Japan Atomic Energy Research Institute (Japan); Ishikawa, Akiyoshi [Japan Atomic Energy Research Institute (Japan); Baldwin, Charles A; Gabbard, William Alexander [Oak Ridge National Laboratory (United States); Malone, Charlie M [Oak Ridge National Laboratory (United States)

2000-07-15

Postirradiation heating tests of TRISO-coated UO{sub 2} particles at 1700 and 1800degC were performed to understand fission product release behavior at accident temperatures. The inventory measurements of the individual particles were carried out before and after the heating tests with gamma-ray spectrometry to study the behavior of the individual particles. The time-dependent release behavior of {sup 85}Kr, {sup 110m}Ag, {sup 134}Cs, {sup 137}Cs, and {sup 154}Eu were obtained with on-line measurements of fission gas release and intermittent measurements of metallic fission product release during the heating tests. The inventory measurements of the individual particles revealed that fission product release behavior of the individual particles was not uniform, and large particle-to-particle variations in the release behavior of {sup 110m}Ag, {sup 134}Cs, {sup 137}Cs, and {sup 154}Eu were found. X-ray microradiography and ceramography showed that the variations could not be explained by only the presence or absence of cracks in the SiC coating layer. The SiC degradation may have been related to the variations.

Focusing of sub-micrometer particles and bacteria enabled by two-dimensional acoustophoresis

DEFF Research Database (Denmark)

Antfolk, M.; Muller, Peter Barkholt; Augustsson, P.

2014-01-01

Handling of sub-micrometer bioparticles such as bacteria are becoming increasingly important in the biomedical field and in environmental and food analysis. As a result, there is an increased need for less labor-intensive and time-consuming handling methods. Here, an acoustophoresis-based microfl......Handling of sub-micrometer bioparticles such as bacteria are becoming increasingly important in the biomedical field and in environmental and food analysis. As a result, there is an increased need for less labor-intensive and time-consuming handling methods. Here, an acoustophoresis......-based microfluidic chip that uses ultrasound to focus sub-micrometer particles and bacteria, is presented. The ability to focus sub-micrometer bioparticles in a standing one-dimensional acoustic wave is generally limited by the acoustic-streaming-induced drag force, which becomes increasingly significant the smaller...... particles as small as 0.5 μm in diameter in microchannels of square or rectangular cross sections, is demonstrated. Numerical analysis was used to determine generic transverse particle trajectories in the channels, which revealed spiral-shaped trajectories of the sub-micrometer particles towards the center...

Particle image velocimetry measurements of 2-dimensional velocity field around twisted tape

Energy Technology Data Exchange (ETDEWEB)

Song, Min Seop; Park, So Hyun; Kim, Eung Soo, E-mail: kes7741@snu.ac.kr

2016-11-01

Highlights: • Measurements of the flow field in a pipe with twisted tape were conducted by particle image velocimetry (PIV). • A novel matching index of refraction technique utilizing 3D printing and oil mixture was adopted to make the test section transparent. • Undistorted particle images were clearly captured in the presence of twisted tape. • 2D flow field in the pipe with twisted tape revealed the characteristic two-peak velocity profile. - Abstract: Twisted tape is a passive component used to enhance heat exchange in various devices. It induces swirl flow that increases the mixing of fluid. Thus, ITER selected the twisted tape as one of the candidates for turbulence promoting in the divertor cooling. Previous study was mainly focused on the thermohydraulic performance of the twisted tape. As detailed data on the velocity field around the twisted tape was insufficient, flow visualization study was performed to provide fundamental data on velocity field. To visualize the flow in a complex structure, novel matching index of refraction technique was used with 3-D printing and mixture of anise and mineral oil. This technique enables the camera to capture undistorted particle image for velocity field measurement. Velocity fields at Reynolds number 1370–9591 for 3 different measurement plane were obtained through particle image velocimetry. The 2-dimensional averaged velocity field data were obtained from 177 pair of instantaneous velocity fields. It reveals the characteristic two-peak flow motion in axial direction. In addition, the normalized velocity profiles were converged with increase of Reynolds numbers. Finally, the uncertainty of the result data was analyzed.

The Particle Habit Imaging and Polar Scattering probe PHIPS: First Stereo-Imaging and Polar Scattering Function Measurements of Ice Particles

Science.gov (United States)

Abdelmonem, A.; Schnaiter, M.; Schön, R.; Leisner, T.

2009-04-01

in December 2008 at the AIDA cloud chamber in the temperature range from -5°C to -70°C. In a series of experiments small externally generated seed ice crystals were grown in AIDA at distinct temperature and saturation ratio conditions. For these experiments the long known ice morphology diagram with the temperature dependent morphology changes and the supersaturation dependent structural complexity could clearly be reproduced by PHIPS. Structural details like hollow crystals, crystals with inclusions, and crystals with stepped surfaces (Hopper crystals) could be resolved by PHIPS. Moreover, the advantage of stereo-imaging in terms of habit classification and particle orientation deduction could be demonstrated. The scattering function measurement reveals ice particle orientation dependent specular reflection peaks which might contain information about the surface roughness. The presentation will describe the instrument set up in detail and highlight some preliminary results.

Coherence factors in a high-tc cuprate probed by quasi-particle scattering off vortices.

Science.gov (United States)

Hanaguri, T; Kohsaka, Y; Ono, M; Maltseva, M; Coleman, P; Yamada, I; Azuma, M; Takano, M; Ohishi, K; Takagi, H

2009-02-13

When electrons pair in a superconductor, quasi-particles develop an acute sensitivity to different types of scattering potential that is described by the appearance of coherence factors in the scattering amplitudes. Although the effects of coherence factors are well established in isotropic superconductors, they are much harder to detect in their anisotropic counterparts, such as high-superconducting-transition-temperature cuprates. We demonstrate an approach that highlights the momentum-dependent coherence factors in Ca2-xNaxCuO2Cl2. We used Fourier-transform scanning tunneling spectroscopy to reveal a magnetic-field dependence in quasi-particle scattering interference patterns that is sensitive to the sign of the anisotropic gap. This result is associated with the d-wave coherence factors and quasi-particle scattering off vortices. Our technique thus provides insights into the nature of electron pairing as well as quasi-particle scattering processes in unconventional superconductors.

Symmetric alignment of the nematic matrix between close penetrable colloidal particles

International Nuclear Information System (INIS)

Teixeira, P I C; Barmes, F; Cleaver, D J

2004-01-01

A simple model is proposed for the liquid crystal matrix surrounding 'soft' colloidal particles whose separation is much smaller than their radii. We use our implementation of the Onsager approximation of density-functional theory (Chrzanowska et al 2001 J. Phys.: Condens. Matter 13 4715) to calculate the structure of a nanometrically thin film of hard Gaussian overlap particles of elongations κ = 3 and 5, confined between two solid walls. The penetrability of either substrate can be tuned independently to yield symmetric or hybrid alignment. Comparison with Monte Carlo simulations of the same system (Cleaver and Teixeira 2001 Chem. Phys. Lett. 338 1, Barmes and Cleaver 2004 in preparation) reveals good agreement in the symmetric case

Fermilab | Science | Particle Physics

Science.gov (United States)

Photos and videos Latest news For the media Particle Physics Neutrinos Fermilab and the LHC Dark matter initiatives Research and development Key discoveries Benefits of particle physics Particle Accelerators society Particle Physics 101 Science of matter, energy, space and time How particle physics discovery

The CERN Resonant Weakly Interacting Sub-eV Particle Search (CROWS)

CERN Document Server

Betz, Michael; Gasior, Marek; Thumm, Manfred

The subject of this thesis is the design, implementation and first results of the ``CERN Resonant WISP Search'' (CROWS) experiment, which probes the existence of Weakly Interacting Sub-eV Particles (WISPs) using microwave techniques. Axion Like Particles and Hidden Sector Photons are two well motivated members of the WISP family. Their existence could reveal the composition of cold dark matter in the universe and explain a large number of astrophysical phenomena. Particularly, the discovery of an axion would solve a long standing issue in the standard model, known as the ``strong CP problem''. Despite their strong theoretical motivation, the hypothetical particles have not been observed in any experiment so far. One way to probe the existence of WISPs is to exploit their interaction with photons in a ``light shining through the wall'' experiment. A laser beam is guided through a strong magnetic field in the ``emitting region'' of the experiment. This provides photons, which can convert into hypothetical Axi...

Effects of Particles Collision on Separating Gas–Particle Two-Phase Turbulent Flows

KAUST Repository

Sihao, L. V.

2013-10-10

A second-order moment two-phase turbulence model incorporating a particle temperature model based on the kinetic theory of granular flow is applied to investigate the effects of particles collision on separating gas–particle two-phase turbulent flows. In this model, the anisotropy of gas and solid phase two-phase Reynolds stresses and their correlation of velocity fluctuation are fully considered using a presented Reynolds stress model and the transport equation of two-phase stress correlation. Experimental measurements (Xu and Zhou in ASME-FED Summer Meeting, San Francisco, Paper FEDSM99-7909, 1999) are used to validate this model, source codes and prediction results. It showed that the particles collision leads to decrease in the intensity of gas and particle vortices and takes a larger effect on particle turbulent fluctuations. The time-averaged velocity, the fluctuation velocity of gas and particle phase considering particles colli-sion are in good agreement with experimental measurements. Particle kinetic energy is always smaller than gas phase due to energy dissipation from particle collision. Moreover, axial– axial and radial–radial fluctuation velocity correlations have stronger anisotropic behaviors. © King Fahd University of Petroleum and Minerals 2013

Elementary particles. 2

International Nuclear Information System (INIS)

Ranft, G.; Ranft, J.

1977-01-01

In this part the subject is covered under the following headings, methods for producing high-energy particles; interaction of high-energy particles with matter; methods for the detection of high-energy particles; symmetry properties and conservation laws; quantum number and selection rules; theorem of scattering behaviour at asymptotically high energies; statistical methods in elementary particle physics; interaction of high-energy particles with nuclei; relations of high-energy physics to other branches of science and its response to engineering. Intended as information on high-energy physics for graduate students and research workers familiar with the fundamentals of classical and quantum physics

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.

Particle-Resolved Modeling of Aerosol Mixing State in an Evolving Ship Plume

Science.gov (United States)

Riemer, N. S.; Tian, J.; Pfaffenberger, L.; Schlager, H.; Petzold, A.

2011-12-01

the vanishing of the volatile nucleation mode consisting of sulfate particles. Detailed process analysis of the simulations revealed that the most important processes shaping the particle distribution were coagulation and dilution with background air. Coagulation significantly altered the mixing state of the particles leading to a continuum of internal mixtures of sulfate, black carbon and organic carbon, while ash particles remained largely externally mixed.

Systems and methods for separating particles utilizing engineered acoustic contrast capture particles

Science.gov (United States)

Kaduchak, Gregory; Ward, Michael D.

2018-03-06

An apparatus for separating particles from a medium includes a capillary defining a flow path therein that is in fluid communication with a medium source. The medium source includes engineered acoustic contrast capture particle having a predetermined acoustic contrast. The apparatus includes a vibration generator that is operable to produce at least one acoustic field within the flow path. The acoustic field produces a force potential minima for positive acoustic contrast particles and a force potential minima for negative acoustic contrast particles in the flow path and drives the engineered acoustic contrast capture particles to either the force potential minima for positive acoustic contrast particles or the force potential minima for negative acoustic contrast particles.

Oblate hemispheroidal Large Ruthenium Particles Supported on Calcium Amide as Efficient Catalysts for Ammonia Decomposition.

Science.gov (United States)

Kishida, Kazuhisa; Kitano, Masaaki; Inoue, Yasunori; Sasase, Masato; Nakao, Takuya; Tada, Tomofumi; Abe, Hitoshi; Niwa, Yasuhiro; Yokoyama, Toshiharu; Hara, Michikazu; Hosono, Hideo

2018-03-30

Ammonia decomposition is positioned as an important technology for abstracting hydrogen from ammonia toward the realization of a hydrogen economy. Here, we report that oblate hemispheroidal large Ru particles on Ca(NH₂)₂ function as efficient catalysts for ammonia decomposition. The turnover frequency (TOF) of Ru/Ca(NH₂)₂ increased by two orders of magnitude as the Ru particle size was increased from 1.5 to 8.4 nm. More than 90% ammonia decomposition was achieved over Ru/Ca(NH₂)₂ with oblate hemispheroidal large Ru particles at 360 ºC, which is comparable to that of alkali-promoted Ru catalysts with small Ru particle sizes. XAFS analyses revealed that Ru particles are immobilized on Ca(NH₂)₂ by Ru-N bonding formed at the metal-support interface, which leads to oblate hemispheroidal Ru particles. Such a strong metal-support interaction in the Ru/Ca(NH₂)₂ is also substantiated by density functional theory calculations. The high activity of Ru/Ca(NH₂)₂ with large Ru particles primarily originates from the shape and appropriate size of Ru particles with a high density of active sites rather than the electron-donating ability of Ca(NH₂)₂. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Particle adhesion and removal

CERN Document Server

Mittal, K L

2015-01-01

The book provides a comprehensive and easily accessible reference source covering all important aspects of particle adhesion and removal.  The core objective is to cover both fundamental and applied aspects of particle adhesion and removal with emphasis on recent developments.  Among the topics to be covered include: 1. Fundamentals of surface forces in particle adhesion and removal.2. Mechanisms of particle adhesion and removal.3. Experimental methods (e.g. AFM, SFA,SFM,IFM, etc.) to understand  particle-particle and particle-substrate interactions.4. Mechanics of adhesion of micro- and  n

Seasonal and particle size-dependent variations in gas/particle partitioning of PCDD/Fs

International Nuclear Information System (INIS)

Lee, Se-Jin; Ale, Debaki; Chang, Yoon-Seok; Oh, Jeong-Eun; Shin, Sun Kyoung

2008-01-01

This study monitored particle size-dependent variations in atmospheric polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Two gas/particle partitioning models, the subcooled liquid vapor pressure (P L 0 ) and the octanol-air partition coefficient (K OA ) model, were applied to each particle sizes. The regression coefficients of each fraction against the gas/particle partition coefficient (K P ) were similar for separated particles within the same sample set but differed for particles collected during different periods. Gas/particle partitioning calculated from the integral of fractions was similar to that of size-segregated particles and previously measured bulk values. Despite the different behaviors and production mechanisms of atmospheric particles of different sizes, PCDD/F partitioning of each size range was controlled by meteorological conditions such as atmospheric temperature, O 3 and UV, which reflects no source related with certain particle size ranges but mixed urban sources within this city. Our observations emphasize that when assessing environmental and health effects, the movement of PCDD/Fs in air should be considered in conjunction with particle size in addition to the bulk aerosol. - Gas/particle partitioning of atmospheric PCDD/Fs for different particle sizes reflects the impacts of emitters of different size ranges

Electrical impedance tomography spectroscopy method for characterising particles in solid-liquid phase

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yanlin [Department of Thermal Energy Engineering, College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing, 102249 (China); Wang, Mi [Institute of Particle Science and Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (China); Yao, Jun [School of Energy Research, Xiamen University, Xiamen 361005 (China)

2014-04-11

based on EIS measurement using a sensor of 8 electrodes are reported. Results have demonstrated the potential as well as revealed the challenge in the use of EIS and EITS for characterisation of particle in suspension.

Quantum chaos in nuclear single-particle motion and damping of giant resonances

International Nuclear Information System (INIS)

Pal, Santanu; Mukhopadhyay, Tapan

1995-01-01

The spectral statistics of single particle motion in deformed cavities with axial symmetry are presented. The single particle motion in the cavities considered are non-integrable and the systematics of the fluctuation measures of the spectra reveal a transition from regular to chaotic regime in the corresponding classical systems. Quantitative estimate of the degree of chaos enables us to introduce a correction factor to the one-body wall formula for the damping widths of isoscalar giant resonances. The damping widths calculated with this correction factor give much better agreement with experimental values than earlier calculations of one-body damping widths. (author). 21 refs., 5 figs

Momentum balance and stresses in a suspension of spherical particles in a plane Couette flow

Science.gov (United States)

Rahmani, Mona; Hammouti, Abdelkader; Wachs, Anthony

2018-04-01

Non-Brownian suspension of monodisperse spherical particles, with volume fractions ranging between ϕ = 0.05 and 0.38 and particle Reynolds numbers ranging between Rep = 0.002 and 20, in plane Couette shear flows is investigated using three-dimensional particle-resolved numerical simulations. We examine the effects of volume fraction and particle Reynolds number on the macroscopic and microscopic stresses in the fluid phase. The effective viscosity of the suspension is in a good agreement with the previous empirical and experimental studies. At Rep = 20, however, the effective viscosity increases significantly compared to the lower particle Reynolds number simulations in the Stokes flow regime. Examining the stresses over the depth of the Couette gap reveals that this increase in wall shear stresses at high particle Reynolds numbers is mainly due to the significantly higher particle phase stress contributions. Next, we examine the momentum balance in the fluid and particle phase for different regimes to assess the significance of particle/particle interaction and fluid and particle inertia. At the highest particle Reynolds number and volume fraction, the particle inertia plays a dominant role in the momentum balance and the fluid inertia is non-negligible, while the short-lived contact forces are negligible compared to these effects. For all other regimes, the fluid inertia is negligible, but the particle inertia and contact forces are important in the momentum balance. Reynolds stresses originated from velocity fluctuations do not contribute significantly to the suspension stresses in any of the regimes we have studied, while the reduction in the shear-induced particle rotation can be a reason for higher wall shear stress at Rep = 20. Finally, we study the kinematics of particles, including their velocity fluctuations, rotation, and diffusion over the depth of the Couette gap. The particle diffusion coefficients in the cross flow direction exhibit an abrupt

The topology dependence of charged particle multiplicities in three-jet events

CERN Document Server

Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Odier, P; Pietrzyk, B; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Miquel, R; Mir, L M; Orteu, S; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Bazarko, A O; Bright-Thomas, P G; Cattaneo, M; Cerutti, F; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Lutters, G; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rizzo, G; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schmitt, M; Schneider, O; Tejessy, W; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Turnbull, R M; Becker, U; Buchmüller, O L; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Schmidt, M; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Moutoussi, A; Nash, J; Sedgbeer, J K; Stacey, A M; Williams, M D; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Williams, M I; Galla, A; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Coyle, P; Diaconu, C A; Etienne, F; Konstantinidis, N P; Leroy, O; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Ragusa, F; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Park, H J; Schune, M H; Simion, S; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Greening, T C; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

1997-01-01

A study of individual jet and whole-event charged particle multiplicities in three-jet events measured in e+e- annihilation at the Z reveals a significant topology dependence. Mean jet multiplicities are inadequately described by jet energies; interjet angles must also be specified. Quantitative tests suggest that it is necessary to use transverse-momentum-like scales to describe the data.

A test particle motion in the Kerr field with fluctuating perturbations

International Nuclear Information System (INIS)

Zhuk, I.T.; Piragas, K.A.

1982-01-01

Motion of a stochastic test particle in the Kerr black hole field in the approximation of Brown interaction is considered. Probability distribution of orbit position by the latitude angle is revealed, bifurcation values of their parameters are determined. Fluctuating instability of orbits characteristic of critical modes of motion is investigated, properties of some statistical characteristics of the system are identified

Free-Standing and Self-Crosslinkable Hybrid Films by Core–Shell Particle Design and Processing

Directory of Open Access Journals (Sweden)

Steffen Vowinkel

2017-11-01

Full Text Available The utilization and preparation of functional hybrid films for optical sensing applications and membranes is of utmost importance. In this work, we report the convenient and scalable preparation of self-crosslinking particle-based films derived by directed self-assembly of alkoxysilane-based cross-linkers as part of a core-shell particle architecture. The synthesis of well-designed monodisperse core-shell particles by emulsion polymerization is the basic prerequisite for subsequent particle processing via the melt-shear organization technique. In more detail, the core particles consist of polystyrene (PS or poly(methyl methacrylate (PMMA, while the comparably soft particle shell consists of poly(ethyl acrylate (PEA and different alkoxysilane-based poly(methacrylates. For hybrid film formation and convenient self-cross-linking, different alkyl groups at the siloxane moieties were investigated in detail by solid-state Magic-Angle Spinning Nuclear Magnetic Resonance (MAS, NMR spectroscopy revealing different crosslinking capabilities, which strongly influence the properties of the core or shell particle films with respect to transparency and iridescent reflection colors. Furthermore, solid-state NMR spectroscopy and investigation of the thermal properties by differential scanning calorimetry (DSC measurements allow for insights into the cross-linking capabilities prior to and after synthesis, as well as after the thermally and pressure-induced processing steps. Subsequently, free-standing and self-crosslinked particle-based films featuring excellent particle order are obtained by application of the melt-shear organization technique, as shown by microscopy (TEM, SEM.

Localization and force analysis at the single virus particle level using atomic force microscopy

International Nuclear Information System (INIS)

Liu, Chih-Hao; Horng, Jim-Tong; Chang, Jeng-Shian; Hsieh, Chung-Fan; Tseng, You-Chen; Lin, Shiming

2012-01-01

Highlights: ► Localization of single virus particle. ► Force measurements. ► Force mapping. -- Abstract: Atomic force microscopy (AFM) is a vital instrument in nanobiotechnology. In this study, we developed a method that enables AFM to simultaneously measure specific unbinding force and map the viral glycoprotein at the single virus particle level. The average diameter of virus particles from AFM images and the specificity between the viral surface antigen and antibody probe were integrated to design a three-stage method that sets the measuring area to a single virus particle before obtaining the force measurements, where the influenza virus was used as the object of measurements. Based on the purposed method and performed analysis, several findings can be derived from the results. The mean unbinding force of a single virus particle can be quantified, and no significant difference exists in this value among virus particles. Furthermore, the repeatability of the proposed method is demonstrated. The force mapping images reveal that the distributions of surface viral antigens recognized by antibody probe were dispersed on the whole surface of individual virus particles under the proposed method and experimental criteria; meanwhile, the binding probabilities are similar among particles. This approach can be easily applied to most AFM systems without specific components or configurations. These results help understand the force-based analysis at the single virus particle level, and therefore, can reinforce the capability of AFM to investigate a specific type of viral surface protein and its distributions.

Dusty-Plasma Particle Accelerator

Science.gov (United States)

Foster, John E.

2005-01-01

A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

Investigating the settling dynamics of cohesive silt particles with particle-resolving simulations

Science.gov (United States)

Sun, Rui; Xiao, Heng; Sun, Honglei

2018-01-01

The settling of cohesive sediment is ubiquitous in aquatic environments, and the study of the settling process is important for both engineering and environmental reasons. In the settling process, the silt particles show behaviors that are different from non-cohesive particles due to the influence of inter-particle cohesive force. For instance, the flocs formed in the settling process of cohesive silt can loosen the packing, and thus the structural densities of cohesive silt beds are much smaller than that of non-cohesive sand beds. While there is a consensus that cohesive behaviors depend on the characteristics of sediment particles (e.g., Bond number, particle size distribution), little is known about the exact influence of these characteristics on the cohesive behaviors. In addition, since the cohesive behaviors of the silt are caused by the inter-particle cohesive forces, the motions of and the contacts among silt particles should be resolved to study these cohesive behaviors in the settling process. However, studies of the cohesive behaviors of silt particles in the settling process based on particle-resolving approach are still lacking. In the present work, three-dimensional settling process is investigated numerically by using CFD-DEM (Computational Fluid Dynamics-Discrete Element Method). The inter-particle collision force, the van der Waals force, and the fluid-particle interaction forces are considered. The numerical model is used to simulate the hindered settling process of silt based on the experimental setup in the literature. The results obtained in the simulations, including the structural densities of the beds, the characteristic lines, and the particle terminal velocity, are in good agreement with the experimental observations in the literature. To the authors' knowledge, this is the first time that the influences of non-dimensional Bond number and particle polydispersity on the structural densities of silt beds have been investigated separately

Simulation of diffusion-induced stress using reconstructed electrodes particle structures generated by micro/nano-CT

International Nuclear Information System (INIS)

Lim, Cheolwoong; Yan Bo; Yin Leilei; Zhu Likun

2012-01-01

Highlights: ► The microstructure of LIB electrodes was obtained by X-ray micro/nano-CT. ► We studied diffusion-induced stresses based on realistic 3D microstructures. ► Stresses depend on geometric characteristics of electrode particle. ► Stresses in a real particle are much higher than those in a spherical particle. - Abstract: Lithium ion batteries experience diffusion-induced stresses during charge and discharge processes which can cause electrode failure in the form of fracture. Previous diffusion-induced stress models and simulations are mainly based on simple active material particle structures, such as spheres and ellipsoids. However, the simple structure model cannot reveal the stress development in a real complex lithium ion battery electrode. In this paper, we studied the diffusion-induced stresses numerically based on a realistic morphology of reconstructed particles during the lithium ion intercalation process. The morphology of negative and positive active materials of a lithium ion battery was determined using X-ray micro/nano computed tomography technology. Diffusion-induced stresses were simulated at different C rates under galvonostatic conditions and compared with spherical particles. The simulation results show that the intercalation stresses of particles depend on their geometric characteristics. The highest von Mises stress and Tresca stress in a real particle are several times higher than the stresses in a spherical particle with the same volume.

Negative mobility of a Brownian particle: Strong damping regime

Science.gov (United States)

Słapik, A.; Łuczka, J.; Spiechowicz, J.

2018-02-01

We study impact of inertia on directed transport of a Brownian particle under non-equilibrium conditions: the particle moves in a one-dimensional periodic and symmetric potential, is driven by both an unbiased time-periodic force and a constant force, and is coupled to a thermostat of temperature T. Within selected parameter regimes this system exhibits negative mobility, which means that the particle moves in the direction opposite to the direction of the constant force. It is known that in such a setup the inertial term is essential for the emergence of negative mobility and it cannot be detected in the limiting case of overdamped dynamics. We analyse inertial effects and show that negative mobility can be observed even in the strong damping regime. We determine the optimal dimensionless mass for the presence of negative mobility and reveal three mechanisms standing behind this anomaly: deterministic chaotic, thermal noise induced and deterministic non-chaotic. The last origin has never been reported. It may provide guidance to the possibility of observation of negative mobility for strongly damped dynamics which is of fundamental importance from the point of view of biological systems, all of which in situ operate in fluctuating environments.

Curvature-induced microswarming and clustering of self-propelled particles

Science.gov (United States)

Bruss, Isaac; Glotzer, Sharon

Non-equilibrium active matter systems exhibit many unique phenomena, such as motility-induced phase separation and swarming. However, little is known about how these behaviors depend on the geometry of the environment. To answer this question, we use Brownian dynamics simulations to study the effects of Gaussian curvature on self-propelled particles by confining them to the surface of a sphere. We find that a modest amount of curvature promotes phase separation by altering the shape of a cluster's boundary. Alternatively, particles on surfaces of high curvature experience reduced phase separation and instead form microswarms, where particles share a common orbit. We show that this novel flocking behavior is distinct from other previously studied examples, in that it is not explicitly incorporated into our model through Vicsek-like alignment rules nor torques. Rather, we find that microswarms emerge solely due to the geometric link between orientation and velocity, a property exclusive to surfaces with non-zero Gaussian curvature. These findings reveal the important role of local environment on the global emergent behavior of non-equilibrium systems. Center for Bio-Inspired Engineering (DOE Award # DE-SC0000989).

Linear particle accelerator

International Nuclear Information System (INIS)

Richards, J.A.

1977-01-01

A linear particle accelerator which provides a pulsed beam of charged particles of uniform energy is described. The accelerator is in the form of an evacuated dielectric tube, inside of which a particle source is located at one end of the tube, with a target or window located at the other end of the dielectric tube. Along the length of the tube are externally located pairs of metal plates, each insulated from each other in an insulated housing. Each of the plates of a pair are connected to an electrical source of voltage of opposed polarity, with the polarity of the voltage of the plates oriented so that the plate of a pair, nearer to the particle source, is of the opposed polarity to the charge of the particle emitted by the source. Thus, a first plate about the tube located nearest the particle source, attracts a particle which as it passes through the tube past the first plate is then repelled by the reverse polarity of the second plate of the pair to continue moving towards the target

Effects of aerodynamic particle interaction in turbulent non-dilute particle-laden flow

DEFF Research Database (Denmark)

Salewski, Mirko; Fuchs, Laszlo

2008-01-01

Aerodynamic four-way coupling models are necessary to handle two-phase flows with a dispersed phase in regimes in which the particles are neither dilute enough to neglect particle interaction nor dense enough to bring the mixture to equilibrium. We include an aerodynamic particle interaction model...... levels in the flow then decrease. The impact of the stochastic particle description on the four-way coupling model is shown to be relatively small. If particles are also allowed to break up according to a wave breakup model, the particles become polydisperse. An ad hoc model for handling polydisperse...

Particle cosmology

CERN Multimedia

CERN. Geneva

2007-01-01

The understanding of the Universe at the largest and smallest scales traditionally has been the subject of cosmology and particle physics, respectively. Studying the evolution of the Universe connects today's large scales with the tiny scales in the very early Universe and provides the link between the physics of particles and of the cosmos. This series of five lectures aims at a modern and critical presentation of the basic ideas, methods, models and observations in today's particle cosmology.

Applying a Particle-only Model to the HL Tau Disk

OpenAIRE

Tabeshian, Maryam; Wiegert, Paul A.

2018-01-01

Observations have revealed rich structures in protoplanetary disks, offering clues about their embedded planets. Due to the complexities introduced by the abundance of gas in these disks, modeling their structure in detail is computationally intensive, requiring complex hydrodynamic codes and substantial computing power. It would be advantageous if computationally simpler models could provide some preliminary information on these disks. Here we apply a particle-only model (that we developed f...

Multi-particle Anderson Localisation: Induction on the Number of Particles

International Nuclear Information System (INIS)

Chulaevsky, Victor; Suhov, Yuri

2009-01-01

This paper is a follow-up of our recent papers Chulaevsky and Suhov (Commun Math Phys 283:479-489, 2008) and Chulaevsky and Suhov (Commun Math Phys in press, 2009) covering the two-particle Anderson model. Here we establish the phenomenon of Anderson localisation for a quantum N-particle system on a lattice with short-range interaction and in presence of an IID external potential with sufficiently regular marginal cumulative distribution function (CDF). Our main method is an adaptation of the multi-scale analysis (MSA; cf. Froehlich and Spencer, Commun Math Phys 88:151-184, 1983; Froehlich et al., Commun Math Phys 101:21-46, 1985; von Dreifus and Klein, Commun Math Phys 124:285-299, 1989) to multi-particle systems, in combination with an induction on the number of particles, as was proposed in our earlier manuscript (Chulaevsky and Suhov 2007). Recently, Aizenman and Warzel (2008) proved spectral and dynamical localisation for N-particle lattice systems with a short-range interaction, using an extension of the Fractional-Moment Method (FMM) developed earlier for single-particle models in Aizenman and Molchanov (Commun Math Phys 157:245-278, 1993) and Aizenman et al. (Commun Math Phys 224:219-253, 2001) (see also references therein) which is also combined with an induction on the number of particles

Magnetic particle mixing with magnetic micro-convection for microfluidics

OpenAIRE

Kitenbergs , Guntars; Erglis , Kaspars; Perzynski , Régine; Cēbers , Andrejs

2015-01-01

International audience; In this paper we discuss the magnetic micro-convection phenomenon as a tool for mixing enhancement in microfluidics systems in cases when one of the mis-cible fluids is a magnetic particle colloid. A system of a water-based magnetic fluid and water is investigated experimentally under homogeneous magnetic field in a Hele-Shaw cell. Subsequent image analysis both qualitatively and quan-titatively reveals the high enhancement of mixing efficiency provided by this method....

Weathering of a carbon nanotube/epoxy nanocomposite under UV light and in water bath: impact on abraded particles

Science.gov (United States)

Schlagenhauf, Lukas; Kianfar, Bahareh; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

2015-11-01

Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of the abraded particles, and the toxicity of abraded particles, measured by in vitro toxicity tests using the THP-1 monocyte-derived macrophages. The results showed that weathering by immersion in water had no influence on the properties of abraded particles. The exposure to UV light caused a degradation of the epoxy on the surface, followed by delamination of an approx. 2.5 μm thick layer. An increased quantity of exposed CNTs in abraded particles was not found; on the contrary, longer UV exposure times decreased the released fraction of CNTs from 0.6% to 0.4%. The toxicity tests revealed that abraded particles from the nanocomposites did not induce additional acute cytotoxic effects compared to particles from the neat epoxy.Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of

Effective particle magnetic moment of multi-core particles

NARCIS (Netherlands)

Ahrentorp, F.; Astalan, A.; Blomgren, J.; Jonasson, C.; Wetterskog, E.; Svedlindh, P.; Lak, A.; Ludwig, F.; Van IJzendoorn, L.J.; Westphal, F.; Grüttner, C.; Gehrke, N.; Gustafsson, S.; Olsson, E.; Johansson, C.

2015-01-01

In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron

Adsorption of acids and bases from aqueous solutions onto silicon dioxide particles.

Science.gov (United States)

Zengin, Huseyin; Erkan, Belgin

2009-12-30

The adsorption of acids and bases onto the surface of silicon dioxide (SiO(2)) particles was systematically studied as a function of several variables, including activation conditions, contact time, specific surface area, particle size, concentration and temperature. The physical properties of SiO(2) particles were investigated, where characterizations were carried out by FT-IR spectroscopy, and morphology was examined by scanning electron microscopy (SEM). The SEM of samples showed good dispersion and uniform SiO(2) particles with an average diameter of about 1-1.5 microm. The adsorption results revealed that SiO(2) surfaces possessed effective interactions with acids and bases, and greatest adsorption capacity was achieved with NaOH, where the best fit isotherm model was the Freundlich adsorption model. The adsorption properties of raw SiO(2) particles were further improved by ultrasonication. Langmuir monolayer adsorption capacity of NaOH adsorbate at 25 degrees C on sonicated SiO(2) (182.6 mg/g) was found to be greater than that of the unsonicated SiO(2) (154.3mg/g). The spontaneity of the adsorption process was established by decreases in DeltaG(ads)(0), which varied from -10.5 to -13.6 kJ mol(-1), in the temperature range 283-338K.

Ghost hunting—an assessment of ghost particle detection and removal methods for tomographic-PIV

International Nuclear Information System (INIS)

Elsinga, G E; Tokgoz, S

2014-01-01

This paper discusses and compares several methods, which aim to remove spurious peaks, i.e. ghost particles, from the volume intensity reconstruction in tomographic-PIV. The assessment is based on numerical simulations of time-resolved tomographic-PIV experiments in linear shear flows. Within the reconstructed volumes, intensity peaks are detected and tracked over time. These peaks are associated with particles (either ghosts or actual particles) and are characterized by their peak intensity, size and track length. Peak intensity and track length are found to be effective in discriminating between most ghosts and the actual particles, although not all ghosts can be detected using only a single threshold. The size of the reconstructed particles does not reveal an important difference between ghosts and actual particles. The joint distribution of peak intensity and track length however does, under certain conditions, allow a complete separation of ghosts and actual particles. The ghosts can have either a high intensity or a long track length, but not both combined, like all the actual particles. Removing the detected ghosts from the reconstructed volume and performing additional MART iterations can decrease the particle position error at low to moderate seeding densities, but increases the position error, velocity error and tracking errors at higher densities. The observed trends in the joint distribution of peak intensity and track length are confirmed by results from a real experiment in laminar Taylor–Couette flow. This diagnostic plot allows an estimate of the number of ghosts that are indistinguishable from the actual particles. (paper)

Injection quality measurements with diamond based particle detectors

CERN Document Server

Stein, Oliver; CERN. Geneva. ATS Department

2016-01-01

During the re-commissioning phase of the LHC after the long shutdown 1 very high beam losses were observed at the TDI during beam injection. The losses reached up to 90% of the dump threshold. To decrease the through beam losses induced stress on the accelerator components these loss levels need to be reduced. Measurements with diamond based particle detectors (dBLMs), which have nano-second time resolution, revealed that the majority of these losses come from recaptured SPS beam surrounding the nominal bunch train. In this MD the injection loss patterns and loss intensities were investigated in greater detail. Performed calibration shots on the TDI (internal beam absorber for injection) gave a conversion factor from impacting particles intensities to signal in the dBLMs (0.1Vs/109 protons). Using the SPS tune kicker for cleaning the recaptured beam in the SPS and changing the LHC injection kicker settings resulted in a reduction of the injection losses. For 144 bunch injections the loss levels were decreased...

Numerical analysis of microstructure formation of magnetic particles and nonmagnetic particles in MR fluids

International Nuclear Information System (INIS)

Ido, Y; Yamaguchi, T; Inagaki, T

2009-01-01

Microstructure formation of magnetic particles and nonmagnetic particles in MR fluids is investigated using the particle method simulation. Nonmagnetic sphere particles are rearranged in the field direction due to the chain-like cluster formation of magnetic particles. In the contrast, the nonmagnetic spherocylinder particles are not sufficiently rearranged in the field direction by using the cluster formation of sphere magnetic particles.

Particle-wall tribology of slippery hydrogel particle suspensions.

Science.gov (United States)

Shewan, Heather M; Stokes, Jason R; Cloitre, Michel

2017-03-08

Slip is an important phenomenon that occurs during the flow of yield stress fluids like soft materials and pastes. Densely packed suspensions of hydrogel microparticles are used to show that slip is governed by the tribological interactions occurring between the samples and shearing surfaces. Both attractive/repulsive interactions between the dispersed particles and surface, as well as the viscoelasticity of the suspension, are found to play key roles in slip occurring within rheometric flows. We specifically discover that for two completely different sets of microgels, the sliding stress at which slip occurs scales with both the modulus of the particles and the bulk suspension modulus. This suggests that hysteresis losses within the viscoelastic particles contribute to friction forces and thus slip at the particle-surface tribo-contact. It is also found that slip during large amplitude oscillatory shear and steady shear flows share the same generic features.

Particle image velocimetry - Principles and first results

International Nuclear Information System (INIS)

Laporta, A.; Marechal, J.P.

1997-01-01

Particle Image Velocimetry (PIV) is a measurement technique elaborated towards the end of the 1970's, but which has developed considerably in recent years. The general principle of PIV is very simple and enables access to instantaneous velocity fields. It consists in recording images of tracer-particles injected into the flow and determining the distance covered by these particles. Since we know the time lapse between successive images of the same particle, we can derive the local fluid velocity. Among the many existing image acquisition and processing methods, the image inter-correlation analysis techniques, used with a pulsed laser source, is the most effective. Since we know the influence of different parameters (number of particles, beam power, time lapse between two successive images, size of query zones, etc.) on the quality of the final result, we can optimize practical adjustment of the PIV measurement scheme. The PIV was tested on the LAVITA hydraulic mockup (simulating the operation of a tangential fan). First results are, all in all, highly satisfactory. These have enabled the rapid drafting of instantaneous mean velocity field maps (20 images acquired in less than 90 seconds, with a post-processing time of about 10 minutes). Observation of the instantaneous fields has evidenced the presence of low frequency non-stationary phenomena which are not revealed by Laser Doppler Velocimetry (LDV). Quantitative comparison between LDV and PIV, concerning average fields, showed close results, with, however, local divergences which could be relatively marked. It must nevertheless be noted that the PIV measurements performed on LAVITA have not been optimized with a view to obtaining a consistently good accuracy level. Priority in the present case was given to the scope of the field explored, with a view to observing the large non-stationary structures within a flow. The PIV measurement technique is thus operational for prompt flow characterization. However

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.

Hydroxyapatite nucleated and grown on nano titania particles enhances recruitment of Escherichia coli for subsequent photocatalytic elimination

International Nuclear Information System (INIS)

Huang, Jing; Liu, Yi; Liu, Yuxin; Li, Hua

2015-01-01

Titania-hydroxyapatite (HA) nanocomposites were fabricated by wet chemical synthesis approach. HA exhibited crystallographic orientation of nucleation on nano titania particle, forming the composite particles with titania being partially enwrapped with HA. Microstructural characterization by high resolution transmission electron microscopy revealed coherent interfacial bond of (110) and (222) planes of HA crystal with (101) plane of anatase. The HA layer promoted significantly recruitment of Escherichia coli bacteria onto the titania-based particles for subsequent photocatalytic killing. Less extent of enwrapping of HA on titania particle, as accomplished by increasing the aging time of HA suspension, gave rise to better capability of photocatalytic degradation of methylene blue and sterilization of the bacteria. The novel HA-enwrapped titania powder shows great potential for environmental applications. - Highlights: • Titania-hydroxyapatite nanocomposite powder was fabricated with cladding structure. • Hydroxyapatite nucleated and grew on titania particle with preferred orientation. • Hydroxyapatite layer promotes recruitment of Escherichia coli onto titania-based particles. • The titania-hydroxyapatite particles show excellent antibacterial performances. • The nanocomposite powder exhibits excellent photocatalytic performances

Hydroxyapatite nucleated and grown on nano titania particles enhances recruitment of Escherichia coli for subsequent photocatalytic elimination

Energy Technology Data Exchange (ETDEWEB)

Huang, Jing; Liu, Yi; Liu, Yuxin; Li, Hua, E-mail: lihua@nimte.ac.cn

2015-02-01

Titania-hydroxyapatite (HA) nanocomposites were fabricated by wet chemical synthesis approach. HA exhibited crystallographic orientation of nucleation on nano titania particle, forming the composite particles with titania being partially enwrapped with HA. Microstructural characterization by high resolution transmission electron microscopy revealed coherent interfacial bond of (110) and (222) planes of HA crystal with (101) plane of anatase. The HA layer promoted significantly recruitment of Escherichia coli bacteria onto the titania-based particles for subsequent photocatalytic killing. Less extent of enwrapping of HA on titania particle, as accomplished by increasing the aging time of HA suspension, gave rise to better capability of photocatalytic degradation of methylene blue and sterilization of the bacteria. The novel HA-enwrapped titania powder shows great potential for environmental applications. - Highlights: • Titania-hydroxyapatite nanocomposite powder was fabricated with cladding structure. • Hydroxyapatite nucleated and grew on titania particle with preferred orientation. • Hydroxyapatite layer promotes recruitment of Escherichia coli onto titania-based particles. • The titania-hydroxyapatite particles show excellent antibacterial performances. • The nanocomposite powder exhibits excellent photocatalytic performances.

A hybrid charged-particle guide for studying (n, charged particle) reactions

International Nuclear Information System (INIS)

Haight, R.C.; White, R.M.; Zinkle, S.J.

1983-01-01

Charged-particle transport systems consisting of magnetic quadrupole lenses have been employed in recent years in the study of (n, charged particle) reactions. A new transport system was completed at the laboratory that is based both on magnetic lenses as well as electrostatic fields. The magnetic focusing of the charged-particle guide is provided by six magnetic quadrupole lenses arranged in a CDCCDC sequence (in the vertical plane). The electrostatic field is produced by a wire at high voltage which stretches the length of the guide and is physically at the centre of the magnetic axis. The magnetic lenses are used for charged particles above 5 MeV; the electrostatic guide is used for lower energies. This hybrid system possesses the excellent focusing and background rejection properties of other magnetic systems. For low energy charged-particles, the electrostatic transport avoids the narrow band-passes in charged-particle energy which are a problem with purely magnetic transport systems. This system is installed at the LLNL Cyclograaff facility for the study of (n, charged particle) reactions at neutron energies up to 35 MeV. (Auth.)

Direct observation of the decay of beauty particles into charm particles

International Nuclear Information System (INIS)

Albanese, J.P.; Alpe, V.; Aoki, S.; Arnold, R.; Baroni, G.; Barth, M.; Bartley, J.H.; Bertrand, D.; Bertrand-Coremans, G.; Bisi, V.; Breslin, A.C.; Carboni, G.; Chesi, E.; Chiba, K.; Cook, G.S.; Coupland, M.; Crosetti, G.; Davis, D.H.; Dell'Uomo, S.; Di Liberto, S.; Bonnelly, W.; Duff, B.G.; Esten, M.J.; Gamba, D.; Gerke, C.; Hazama, M.; Heymann, F.F.; Hoshino, K.; Imrie, D.C.; Isokane, Y.; Kazuno, M.; Kodama, Y.; Lush, G.J.; Maeda, Y.; Marzari-Chiesa, A.; Mazzoni, M.A.; Meddi, F.; Miyanishi, M.; Montwill, A.; Muciaccia, M.T.; Musset, P.; Nakamura, M.; Nakazawa, K.; Natali, S.; Niu, K.; Niwa, K.; Nuzzo, S.; Ohashi, M.; Piuz, F.; Poulard, G.; Ramello, L.; Riccati, L.; Romano, G.; Roosen, R.; Rosa, G.; Ruggieri, F.; Sato, Y.; Sasaki, H.; Sgarbi, C.; Shibuya, H.; Simone, S.; Sletten, H.; Tasaka, S.; Tesuka, I.; Tomita, Y.; Tovee, D.N.; Trent, P.; Tsuneoka, Y.; Ushida, N.; Yamakawa, O.; Yanagisawa, Y.; Aichi Women's Coll., Nisshin-Cho; Bari Univ.; Istituto Nazionale di Fisica Nucleare, Bari; Birkbeck Coll., London; Interuniversity Inst. for High Energies, Brussels; European Organization for Nuclear Research, Geneva; University Coll., Dublin; Gifu Univ.; University Coll., London; Nagoya Univ.; Nagoya Inst. of Tech.; Rome Univ.; Istituto Nazionale di Fisica Nucleare, Rome; Toho Univ., Funabashi, Chiba; Istituto Nazionale di Fisica Nucleare, Turin; Turin Univ.; Utsunomiya Univ.; Yokohama National Univ.

1985-01-01

The associated production of a pair of beauty particles B - and anti B 0 by a 350 GeV π - interaction has been observed in an emulsion target inserted in an array of silicon microstrip detectors. Both beauty particles decay into charm particles, both of which are also observed to decay in the emulsion. Two negative muons were identified and their momenta measured in a large muon spectrometer. One muon has a psub(T) of 1.9 GeV/c and is associated with a beauty particle decay. The other, with a psub(T) of 0.45 GeV/c is associated with a charm particle decay. The flight times of the two beauty particles are respectively (0.8+-0.1).10 -13 s and (5sub(-1) +2 ).10 -13 s. Alternative interpretations of this event have negligible probability. (orig.)

Measurements and calculations of doses from radioactive particles

International Nuclear Information System (INIS)

Leroux, J.B.; Herbaut, Y.

1996-01-01

Three Mile Island (TMI) and Tchernobyl reactor accidents have revealed the importance of the skin exposure to beta radiation produced by small high activity sources, named 'hot particles'. In nuclear power reactors, they may arise as small fragments of irradiated fuel or material which have been neutron activated by passing through the reactor co. In recent years, skin exposure to hot particles has been subject to different limitation criteria, formulated by AIEA, ICRP, NCRP working groups. The present work is the contribution of CEA Grenoble to a contract of the Commission of the European communities in cooperation with several laboratories: University of Birmingham, University of Toulouse and University of Montpellier with the main goal to check experiments and calculations of tissue dose from 60 Co radioactive particles. This report is split up into two parts: hot particle dosimetry close to a 60 Co spherical sample with an approximately 200 μm diameter, using a PTW extrapolation chamber model 233991; dose calculations from two codes: the Varskin Mod 2 computer code and the Hot 25 S2 Monte Carlo algorithm. The two codes lead to similar results; nevertheless there is a large discrepancy (of about 2) between calculations and PTW measurements which are higher by a factor of 1.9. At a 70 μm skin depth and for 1 cm 2 irradiated area, the total (β + γ) tissue dose rate delivered by a spherical ( φ = 200 μm) 60 Co source, in contact with skin, is of the order of 6.1 10 -2 nGy s -1 Bq -1 . (author)

Fluidization of spherocylindrical particles

Science.gov (United States)

Mahajan, Vinay V.; Nijssen, Tim M. J.; Fitzgerald, Barry W.; Hofman, Jeroen; Kuipers, Hans; Padding, Johan T.

2017-06-01

Multiphase (gas-solid) flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like) particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.

Light scattering by cosmic particles

NARCIS (Netherlands)

Hovenier, J.W.; Min, M.

2008-01-01

We define cosmic particles as particles outside the Earth. Two types of cosmic particles can be distinguished, namely liquid and solid particles. The solid particles are often called grains or cosmic dust particles. Cosmic particles occur in a great variety of astronomical objects and environments.

Particle accelerators, colliders, and the story of high energy physics charming the cosmic snake

CERN Document Server

Jayakumar, Raghavan

2012-01-01

The Nordic mythological Cosmic Serpent, Ouroboros, is said to be coiled in the depths of the sea, surrounding the Earth with its tail in its mouth. In physics, this snake is a metaphor for the Universe, where the head, symbolizing the largest entity – the Cosmos – is one with the tail, symbolizing the smallest – the fundamental particle. Particle accelerators, colliders and detectors are built by physicists and engineers to uncover the nature of the Universe while discovering its building blocks. “Charming the Cosmic Snake” takes the readers through the science behind these experimental machines: the physics principles that each stage of the development of particle accelerators helped to reveal, and the particles they helped to discover. The book culminates with a description of the Large Hadron Collider, one of the world’s largest and most complex machines operating in a 27-km circumference tunnel near Geneva. That collider may prove or disprove many of our basic theories about the nature of matt...

Effect of magnetic helicity upon rectilinear propagation of charged particles in random magnetic fields

Science.gov (United States)

Earl, James A.

1992-01-01

When charged particles spiral along a large constant magnetic field, their trajectories are scattered by any random field components that are superposed on the guiding field. If the random field configuration embodies helicity, the scattering is asymmetrical with respect to a plane perpendicular to the guiding field, for particles moving into the forward hemisphere are scattered at different rates from those moving into the backward hemisphere. This asymmetry gives rise to new terms in the transport equations that describe propagation of charged particles. Helicity has virtually no impact on qualitative features of the diffusive mode of propagation. However, characteristic velocities of the coherent modes that appear after a highly anisotropic injection exhibit an asymmetry related to helicity. Explicit formulas, which embody the effects of helicity, are given for the anisotropies, the coefficient diffusion, and the coherent velocities. Predictions derived from these expressions are in good agreement with Monte Carlo simulations of particle transport, but the simulations reveal certain phenomena whose explanation calls for further analytical work.

Compact particle accelerator

Energy Technology Data Exchange (ETDEWEB)

Elizondo-Decanini, Juan M.

2017-08-29

A compact particle accelerator having an input portion configured to receive power to produce particles for acceleration, where the input portion includes a switch, is provided. In a general embodiment, a vacuum tube receives particles produced from the input portion at a first end, and a plurality of wafer stacks are positioned serially along the vacuum tube. Each of the plurality of wafer stacks include a dielectric and metal-oxide pair, wherein each of the plurality of wafer stacks further accelerate the particles in the vacuum tube. A beam shaper coupled to a second end of the vacuum tube shapes the particles accelerated by the plurality of wafer stacks into a beam and an output portion outputs the beam.

Particle Image Velocimetry Applications of Fluorescent Dye-Doped Particles

OpenAIRE

Petrosky, Brian Joseph

2015-01-01

Laser flare can often be a major issue in particle image velocimetry (PIV) involving solid boundaries in a flow or a gas-liquid interface. The use of fluorescent light from dye-doped particles has been demonstrated in water applications, but reproducing the technique in an airflow is more difficult due to particle size constraints and safety concerns. The following thesis is formatted in a hybrid manuscript style, including a full paper presenting the applications of fluorescent Kiton R...

Fermilab | Particle Physics Division

Science.gov (United States)

Diversity Education Safety Sustainability and Environment Contact Science Science Particle Physics Neutrinos Scientific Computing Research & Development Key Discoveries Benefits of Particle Physics Particle Superconducting Test Accelerator LHC and Future Accelerators Accelerators for Science and Society Particle Physics

Computational Modelling of Gas-Particle Flows with Different Particle Morphology in the Human Nasal Cavity

Directory of Open Access Journals (Sweden)

Kiao Inthavong

2009-01-01

Full Text Available This paper summarises current studies related to numerical gas-particle flows in the human nasal cavity. Of interest are the numerical modelling requirements to consider the effects of particle morphology for a variety of particle shapes and sizes such as very small particles sizes (nanoparticles, elongated shapes (asbestos fibres, rough shapes (pollen, and porous light density particles (drug particles are considered. It was shown that important physical phenomena needed to be addressed for different particle characteristics. This included the Brownian diffusion for submicron particles. Computational results for the nasal capture efficiency for nano-particles and various breathing rates in the laminar regime were found to correlate well with the ratio of particle diffusivity to the breathing rate. For micron particles, particle inertia is the most significant property and the need to use sufficient drag laws is important. Drag correlations for fibrous and rough surfaced particles were investigated to enable particle tracking. Based on the simulated results, semi-empirical correlations for particle deposition were fitted in terms of Peclet number and inertial parameter for nanoparticles and micron particles respectively.

Magneto-Hydrodynamic Activity and Energetic Particles - Application to Beta Alfven Eigenmodes

International Nuclear Information System (INIS)

Nguyen, Ch.

2009-12-01

The goal of magnetic fusion research is to extract the power released by fusion reactions and carried by the product of these reactions, liberated at energies of the order of a few MeV. The feasibility of fusion energy production relies on our ability to confine these energetic particles, while keeping the thermonuclear plasma in safe operating conditions. For that purpose, it is necessary to understand and find ways to control the interaction between energetic particles and the thermonuclear plasma. Reaching these two goals is the general motivation for this work. More specifically, our focus is on one type of instability, the Beta Alfven Eigenmode (BAE), which can be driven by energetic particles and impact on the confinement of both energetic and thermal particles. In this work, we study the characteristics of BAEs analytically and derive its dispersion relation and structure. Next, we analyze the linear stability of the mode in the presence of energetic particles. First, a purely linear description is used, which makes possible to get an analytical linear criterion for BAE destabilization in the presence of energetic particles. This criterion is compared with experiments conducted in the Tore-Supra tokamak. Secondly, because the linear analysis reveals some features of the BAE stability which are subject to a strong nonlinear modification, the question is raised of the possibility of a sub-critical activity of the mode. We propose a simple scenario which makes possible the existence of meta-stable modes, verified analytically and numerically. Such a scenario is found to be relevant to the physics and scales characterizing BAEs. (author)

On the transport, segregation, and dispersion of heavy and light particles interacting with rising thermal plumes

Science.gov (United States)

Lappa, Marcello

2018-03-01

A systematic numerical analysis is carried out on the multiplicity of patterns produced by inertial particles dispersed in a fluid and localized gravitational convection developing in the form of a rising thermal plume. In particular, specific numerical examples are presented to provide inputs for an increased understanding of the underlying flow-particle interaction mechanisms and cause-and-effect relationships. A rich spectrum of convective dynamics is obtained at the relatively high value of the considered Rayleigh number (Ra = 108), which naturally allows the investigation of several intriguing effects (including, but not limited to, particle interaction with plume jet, associated vortices, shear instabilities, and symmetry breaking phenomena). An important degree of freedom is introduced in the problem by changing the particle viscous drag through proper tuning of the related Stokes number (St). Similarly, inertia and weight of solid matter are varied parametrically by performing numerical simulations for both light and heavy particles at different values of the Froude number. This framework lets us identify the average behavior of particles by revealing the mean evolution. We connect such statistics to the behavior of the temporally evolving thermal plume, giving deeper insights into the particle transport mechanisms and associated dissipative dynamics.

Rapid, topology-based particle tracking for high-resolution measurements of large complex 3D motion fields.

Science.gov (United States)

Patel, Mohak; Leggett, Susan E; Landauer, Alexander K; Wong, Ian Y; Franck, Christian

2018-04-03

Spatiotemporal tracking of tracer particles or objects of interest can reveal localized behaviors in biological and physical systems. However, existing tracking algorithms are most effective for relatively low numbers of particles that undergo displacements smaller than their typical interparticle separation distance. Here, we demonstrate a single particle tracking algorithm to reconstruct large complex motion fields with large particle numbers, orders of magnitude larger than previously tractably resolvable, thus opening the door for attaining very high Nyquist spatial frequency motion recovery in the images. Our key innovations are feature vectors that encode nearest neighbor positions, a rigorous outlier removal scheme, and an iterative deformation warping scheme. We test this technique for its accuracy and computational efficacy using synthetically and experimentally generated 3D particle images, including non-affine deformation fields in soft materials, complex fluid flows, and cell-generated deformations. We augment this algorithm with additional particle information (e.g., color, size, or shape) to further enhance tracking accuracy for high gradient and large displacement fields. These applications demonstrate that this versatile technique can rapidly track unprecedented numbers of particles to resolve large and complex motion fields in 2D and 3D images, particularly when spatial correlations exist.

Particle Swarm Optimization

Science.gov (United States)

Venter, Gerhard; Sobieszczanski-Sobieski Jaroslaw

2002-01-01

The purpose of this paper is to show how the search algorithm known as particle swarm optimization performs. Here, particle swarm optimization is applied to structural design problems, but the method has a much wider range of possible applications. The paper's new contributions are improvements to the particle swarm optimization algorithm and conclusions and recommendations as to the utility of the algorithm, Results of numerical experiments for both continuous and discrete applications are presented in the paper. The results indicate that the particle swarm optimization algorithm does locate the constrained minimum design in continuous applications with very good precision, albeit at a much higher computational cost than that of a typical gradient based optimizer. However, the true potential of particle swarm optimization is primarily in applications with discrete and/or discontinuous functions and variables. Additionally, particle swarm optimization has the potential of efficient computation with very large numbers of concurrently operating processors.

Decomposition and particle release of a carbon nanotube/epoxy nanocomposite at elevated temperatures

International Nuclear Information System (INIS)

Schlagenhauf, Lukas; Kuo, Yu-Ying; Bahk, Yeon Kyoung; Nüesch, Frank; Wang, Jing

2015-01-01

Carbon nanotubes (CNTs) as fillers in nanocomposites have attracted significant attention, and one of the applications is to use the CNTs as flame retardants. For such nanocomposites, possible release of CNTs at elevated temperatures after decomposition of the polymer matrix poses potential health threats. We investigated the airborne particle release from a decomposing multi-walled carbon nanotube (MWCNT)/epoxy nanocomposite in order to measure a possible release of MWCNTs. An experimental set-up was established that allows decomposing the samples in a furnace by exposure to increasing temperatures at a constant heating rate and under ambient air or nitrogen atmosphere. The particle analysis was performed by aerosol measurement devices and by transmission electron microscopy (TEM) of collected particles. Further, by the application of a thermal denuder, it was also possible to measure non-volatile particles only. Characterization of the tested samples and the decomposition kinetics were determined by the usage of thermogravimetric analysis (TGA). The particle release of different samples was investigated, of a neat epoxy, nanocomposites with 0.1 and 1 wt% MWCNTs, and nanocomposites with functionalized MWCNTs. The results showed that the added MWCNTs had little effect on the decomposition kinetics of the investigated samples, but the weight of the remaining residues after decomposition was influenced significantly. The measurements with decomposition in different atmospheres showed a release of a higher number of particles at temperatures below 300 °C when air was used. Analysis of collected particles by TEM revealed that no detectable amount of MWCNTs was released, but micrometer-sized fibrous particles were collected

Decomposition and particle release of a carbon nanotube/epoxy nanocomposite at elevated temperatures

Science.gov (United States)

Schlagenhauf, Lukas; Kuo, Yu-Ying; Bahk, Yeon Kyoung; Nüesch, Frank; Wang, Jing

2015-11-01

Carbon nanotubes (CNTs) as fillers in nanocomposites have attracted significant attention, and one of the applications is to use the CNTs as flame retardants. For such nanocomposites, possible release of CNTs at elevated temperatures after decomposition of the polymer matrix poses potential health threats. We investigated the airborne particle release from a decomposing multi-walled carbon nanotube (MWCNT)/epoxy nanocomposite in order to measure a possible release of MWCNTs. An experimental set-up was established that allows decomposing the samples in a furnace by exposure to increasing temperatures at a constant heating rate and under ambient air or nitrogen atmosphere. The particle analysis was performed by aerosol measurement devices and by transmission electron microscopy (TEM) of collected particles. Further, by the application of a thermal denuder, it was also possible to measure non-volatile particles only. Characterization of the tested samples and the decomposition kinetics were determined by the usage of thermogravimetric analysis (TGA). The particle release of different samples was investigated, of a neat epoxy, nanocomposites with 0.1 and 1 wt% MWCNTs, and nanocomposites with functionalized MWCNTs. The results showed that the added MWCNTs had little effect on the decomposition kinetics of the investigated samples, but the weight of the remaining residues after decomposition was influenced significantly. The measurements with decomposition in different atmospheres showed a release of a higher number of particles at temperatures below 300 °C when air was used. Analysis of collected particles by TEM revealed that no detectable amount of MWCNTs was released, but micrometer-sized fibrous particles were collected.

Decomposition and particle release of a carbon nanotube/epoxy nanocomposite at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Schlagenhauf, Lukas [Empa - Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers (Switzerland); Kuo, Yu-Ying; Bahk, Yeon Kyoung [Empa - Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Advanced Analytical Technologies (Switzerland); Nüesch, Frank [Empa - Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers (Switzerland); Wang, Jing, E-mail: Jing.Wang@ifu.baug.ethz.ch [Empa - Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Advanced Analytical Technologies (Switzerland)

2015-11-15

Carbon nanotubes (CNTs) as fillers in nanocomposites have attracted significant attention, and one of the applications is to use the CNTs as flame retardants. For such nanocomposites, possible release of CNTs at elevated temperatures after decomposition of the polymer matrix poses potential health threats. We investigated the airborne particle release from a decomposing multi-walled carbon nanotube (MWCNT)/epoxy nanocomposite in order to measure a possible release of MWCNTs. An experimental set-up was established that allows decomposing the samples in a furnace by exposure to increasing temperatures at a constant heating rate and under ambient air or nitrogen atmosphere. The particle analysis was performed by aerosol measurement devices and by transmission electron microscopy (TEM) of collected particles. Further, by the application of a thermal denuder, it was also possible to measure non-volatile particles only. Characterization of the tested samples and the decomposition kinetics were determined by the usage of thermogravimetric analysis (TGA). The particle release of different samples was investigated, of a neat epoxy, nanocomposites with 0.1 and 1 wt% MWCNTs, and nanocomposites with functionalized MWCNTs. The results showed that the added MWCNTs had little effect on the decomposition kinetics of the investigated samples, but the weight of the remaining residues after decomposition was influenced significantly. The measurements with decomposition in different atmospheres showed a release of a higher number of particles at temperatures below 300 °C when air was used. Analysis of collected particles by TEM revealed that no detectable amount of MWCNTs was released, but micrometer-sized fibrous particles were collected.

Interphasial energy transfer and particle dissipation in particle-laden wall turbulence

NARCIS (Netherlands)

Zhao, L.; Andersson, H.I.; Gillissen, J.J.J.

2013-01-01

Transfer of mechanical energy between solid spherical particles and a Newtonian carrier fluid has been explored in two-way coupled direct numerical simulations of turbulent channel flow. The inertial particles have been treated as individual point particles in a Lagrangian framework and their

Magnetic particle tracking for nonspherical particles in a cylindrical fluidized bed

NARCIS (Netherlands)

Buist, K.A.; Jayaprakash, P.; Kuipers, J.A.M.; Deen, N.G.; Padding, J.T.

2017-01-01

In granular flow operations, often particles are nonspherical. This has inspired a vast amount of research in understanding the behavior of these particles. Various models are being developed to study the hydrodynamics involving nonspherical particles. Experiments however are often limited to obtain

Investigating motion and stability of particles in flows using numerical models

Science.gov (United States)

Khurana, Nidhi

motion of animals. Then, we present results on the dynamics of ordered particle arrays in parallel wall channels, under creeping flow conditions. Our Stokesian dynamics simulations reveal that confining walls significantly affect the evolution of force-driven particle arrays, leading to hydrodynamically induced collective phenomena such as propagation of particle-displacement waves. Finally, we analyze the motion of an infinite linear particle chain in channels of different widths and illustrate that confinement strongly affects the stability of particle arrays. We then explain this change of behavior using a simple continuum model.

Particle creation and particle number in an expanding universe

International Nuclear Information System (INIS)

Parker, Leonard

2012-01-01

I describe the logical basis of the method that I developed in 1962 and 1963 to define a quantum operator corresponding to the observable particle number of a quantized free scalar field in a spatially-flat isotropically expanding (and/or contracting) universe. This work also showed for the first time that particles were created from the vacuum by the curved spacetime of an expanding spatially-flat Friedmann–Lemaître–Robertson–Walker (FLRW) universe. The same process is responsible for creating the nearly scale-invariant spectrum of quantized perturbations of the inflaton scalar field during the inflationary stage of the expansion of the universe. I explain how the method that I used to obtain the observable particle number operator involved adiabatic invariance of the particle number (hence, the name adiabatic regularization) and the quantum theory of measurement of particle number in an expanding universe. I also show how I was led in a surprising way, to the discovery in 1964 that there would be no particle creation by these spatially-flat FLRW universes for free fields of any integer or half-integer spin satisfying field equations that are invariant under conformal transformations of the metric. The methods I used to define adiabatic regularization for particle number were based on generally-covariant concepts like adiabatic invariance and measurement that were fundamental and determined results that were unique to each given adiabatic order. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker's 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’. (paper)

Direct observation of the decay of beauty particles into charm particles

Energy Technology Data Exchange (ETDEWEB)