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Showing papers on "Particle published in 1996"


Journal ArticleDOI
28 Jun 1996-Science
TL;DR: Tetrahedral, cubic, irregular-prismatic, icosahedral, and cubo-octahedral particle shapes were observed, whose distribution was dependent on the concentration ratio of the capping polymer material to the platinum cation.
Abstract: The shapes and sizes of platinum nanoparticles were controlled by changes in the ratio of the concentration of the capping polymer material to the concentration of the platinum cations used in the reductive synthesis of colloidal particles in solution at room temperature. Tetrahedral, cubic, irregular-prismatic, icosahedral, and cubo-octahedral particle shapes were observed, whose distribution was dependent on the concentration ratio of the capping polymer material to the platinum cation. Controlling the shape of platinum nanoparticles is potentially important in the field of catalysis.

2,305 citations


Journal ArticleDOI
06 Mar 1996-Langmuir
TL;DR: In this article, a method to control the growth of particle arrays on smooth and wettable solid surfaces is presented. But the results show that the higher the particle monodispersity, the lower the particle volume fraction, and the higher environmental humidity, the larger the size of the forming domains.
Abstract: Forming regular textures of an arbitrary size on smooth solid surfaces is the challenge of future technology to produce new types of optical gratings, optical filters, antireflective surface coatings, selective solar absorbers, data storage, and microelectronics. Here we present a novel approach to form such sophisticated textures: controlling the growth of particle arrays on smooth and wettable solid surfaces. The obtained centimeter-size polycrystalline monolayer films consist of closely packed fine particles. Coloring of the monolayer which arises from the light diffraction, interference, and scattering exclusively inherent in textured films shows the size of the differently oriented crystal domains building the film. The results show that the higher the particle monodispersity, the lower the particle volume fraction, and the higher the environmental humidity, the larger the size of the forming domains.

900 citations


Journal ArticleDOI
01 Jun 1996
TL;DR: This work is, to their knowledge, the first demonstration of three-dimensional trapping of a spherical low-index particle using a single, stationary beam using a stationary, focused Gaussian beam containing an optical vortex.
Abstract: Summary form only given. We demonstrate that a low-index dielectric particle can be stably trapped in three-dimensions using a stationary, focused Gaussian beam containing an optical vortex. This work is, to our knowledge, the first demonstration of three-dimensional trapping of a spherical low-index particle using a single, stationary beam. Vortex traps allow the trapping of low- and high-index particles with less risk of damage and better isolation.

829 citations


Journal ArticleDOI
03 May 1996-Science
TL;DR: The ability to modulate this “lateral attraction” between particles, by adjusting field strength or frequency, facilitates the reversible formation of two-dimensional fluid and crystalline colloidal states on the electrode surface.
Abstract: An electrohydrodynamic methodology has been developed that makes possible the precise assembly of two- and three-dimensional colloidal crystals on electrode surfaces. Electrophoretically deposited colloidal particles were observed to move toward one another over very large distances (greater than five particle diameters) to form two-dimensional colloidal crystals for both micrometer- and nanometer-size particles. This coalescence of particles with the same charge is opposite to what is expected from electrostatic considerations and appears to result from electrohydrodynamic fluid flow arising from an ionic current flowing through the solution. The ability to modulate this "lateral attraction" between particles, by adjusting field strength or frequency, facilitates the reversible formation of two-dimensional fluid and crystalline colloidal states on the electrode surface. Further manipulation allows controlled structures to be assembled.

636 citations


Journal ArticleDOI
TL;DR: In this paper, a new particle breakage factor, B 10, is proposed that will allow easy permeability computations for all types of soil tests, such as finite-element analysis.
Abstract: Particle breakage occurs when the stresses imposed on soil particles exceed their strength. To quantify the amount of breakage, many particle breakage factors have been proposed. Correlations of particle breakage parameters with standard soil parameters such as effective mean normal stress at failure and void ratio at failure do not provide a fully unified correlation with many different types of tests. However, particle breakage factors appear to correlate very well with the total energy input into the test specimen, thus providing a single unifying parameter for all types of soil tests. Therefore, the amount of particle crushing may be predicted if the stresses and strains in the soil can be estimated, such as in a finite-element analysis. The principal significant use of these particle breakage factors may be related to permeability estimates when there are changes in gradation due to particle breakage. A new particle breakage factor, B 10 , is proposed that will allow easy permeability computations wh...

626 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe a parameterization of the global mineral aerosol size distribution in a transport model using eight size classes between 0.1 and 10 μm, and the model prescribes the initial size distribution using soil texture data and particle size measurements close to the ground.
Abstract: The radiative parameters of mineral aerosols are strongly dependent on particle size. Therefore explicit modeling of particle size distribution is needed to calculate the radiative effects and the climate impact of mineral dust. We describe a parameterization of the global mineral aerosol size distribution in a transport model using eight size classes between 0.1 and 10 μm. The model prescribes the initial size distribution using soil texture data and aerosol size measurements close to the ground. During transport, the size distribution changes as larger particles settle out faster than smaller particles. Results of Mie scattering calculations of radiative parameters (extinction efficiency, single scattering albedo, asymmetry parameter) of mineral dust are shown at wavelengths between 0.3 and 30 μm for effective particle radii between 0.1 and 10 μm. Also included are radiative properties (reflection, absorption, transmission) calculated for a dust optical thickness of 0.1. Preliminary studies with the Goddard Institute for Space Studies (GISS) general circulation model (GCM), using two particle size modes, show regional changes in radiative flux at the top of the atmosphere as large as +15 W m -2 at solar and +5 W m -2 at thermal wavelengths in the annual mean, indicating that dust forcing is an important factor in the global radiation budget.

618 citations


Journal ArticleDOI
TL;DR: A multiphase particle-in-cell (MP-PIC) method has been developed in this article, which uses an accurate mapping from Lagrangian particles to and from a computational grid, while on the grid, derivative terms that treat the particle phase as a fluid are readily evaluated and then mapped back to individual particles.

588 citations


Journal ArticleDOI
15 May 1996-Langmuir
TL;DR: In this article, an emulsion-based technique for the assembly of colloid particles into microstructured or multicomponent clusters (supraparticles) is described, where the particles are gathered, assembled, and fixed together in the restricted, colloid-size 2D or 3D space provided by emulsion droplets.
Abstract: We describe an emulsion-based technique that allows the assembly of colloid particles into microstructured or multicomponent clusters (“supraparticles”). The particles are gathered, assembled, and fixed together in the restricted, colloid-size 2D or 3D space provided by emulsion droplets. The process is carried out by multiple modification of the colloid interactions within the particle/droplet system“interaction-tailored colloid assembly”. In the first paper of the series we provide a general description of the method. Then we present the data on the assembly of negatively charged (sulfate) or positively charged (amidine) latexes into ordered hollow spherical supraparticles. The following steps are included in the assembly schemes: (1) modification of latex surface charge and properties, so the microspheres are able to adsorb on the droplet surfaces but without homocoagulation; (2) adsorption and structure formation around the emulsion drops (at this stage the interfacial mobility of the particles is of...

562 citations


Journal ArticleDOI
TL;DR: In this paper, the particle sticking probability p, defined as the ratio of bound particles to the number of particles reaching the surface in a given time period, can be determined from a knowledge of the particle radius, solution concentration, temperature, and solution viscosity; for surfaces derivatized with (3-mercaptopropyl)trimethoxysilane (MPTMS), p ≈ 1.
Abstract: This paper details the kinetic aspects of covalent self-assembly of colloidal Au particles from solution onto immobilized organosilane polymers. On glass substrates, surface formation can be monitored using UV−vis spectroscopy and field emission scanning electron microscopy (FE-SEM). Correlation of these data allows the effect of nanostructure on bulk optical properties to be evaluated. At short derivatization times, particle coverage is proportional to (time)1/2. The particle sticking probability p, defined as the ratio of bound particles to the number of particles reaching the surface in a given time period, can be determined from a knowledge of the particle radius, solution concentration, temperature, and solution viscosity; for surfaces derivatized with (3-mercaptopropyl)trimethoxysilane (MPTMS), p ≈ 1. At longer derivatization times, interparticle repulsions result in a “saturation” coverage at ≈30% of a close-packed monolayer. Two approaches for modulating the rate of surface formation are described...

516 citations


Journal ArticleDOI
TL;DR: In this paper, a generalized Galerkin finite element formulation was developed to simulate the motion of a large number of solid particles in a flowing liquid, where the nodes in the interior of the fluid were computed using Laplace's equation to guarantee a smoothly varying distribution of the nodes.

449 citations


Journal ArticleDOI
15 May 1996-Langmuir
TL;DR: In this article, a flexible and general approach to formation of macroscopic colloidal Au surfaces that have well-defined nanostructure is presented. But the assembly method described in this paper is compared with previous methods for controlling the na...
Abstract: Covalent attachment of nanometer-scale colloidal Au particles to organosilane-coated substrates is a flexible and general approach to formation of macroscopic Au surfaces that have well-defined nanostructure. Variations in substrate (glass, metal, Al2O3), geometry (planar, cylindrical), functional group (−SH, −P(C6H5)2, −NH2, −CN), and particle diameter (2.5−120 nm) demonstrate that each component of these assemblies can be changed without adverse consequences. Information about particle coverage and interparticle spacing has been obtained using atomic force microscopy, field emission scanning electron microscopy, and quartz crystal microgravimetry. Bulk surface properties have been probed with UV−vis spectroscopy, cyclic voltammetry, and surface enhanced Raman scattering. Successful application of the latter two techniques indicates that these substrates may have value for Raman and electrochemical measurements. The assembly method described herein is compared with previous methods for controlling the na...

Journal ArticleDOI
TL;DR: In this paper, reversible electrochemistry of horse heart cytochrome c (Cc) was obtained at SnO2 electrodes modified with 12-nm-diameter colloidal Au particles.
Abstract: Reversible electrochemistry of horse heart cytochrome c (Cc) has been obtained at SnO2 electrodes modified with 12-nm-diameter colloidal Au particles. Previous experiments had demonstrated electrochemical addressability of these particle ensembles; the high current densities and small peak-to-peak separations observed for Cc are indicative of facile electron transfer. In contrast to previously described modified electrodes for Cc, these data were acquired without polishing and without any modification of the Au particle surface. Quasireversible voltammetry was obtained with surfaces comprising monodisperse 36-nm-diameter and polydisperse 6-nm-diameter Au particles, but no voltammetric wave for Cc was seen at surfaces composed of aggregates of 12-nm-diameter or 22-nm-diameter Au particles. These data indicate that nanometer-scale morphology of metals plays a key role in protein electrochemistry, and suggest that isolated, surface-confined colloidal Au particles may be useful building blocks for macroscopic...

Journal ArticleDOI
TL;DR: In this article, the effect of particle size on the electron transport and magnetic properties of La0.7Ca0.3MnO3 has been investigated and it was shown that the maximum magnetoresistance exhibited by the samples near Tc is not sensitive to the particle size.
Abstract: Effect of particle size on the electron transport and magnetic properties of La0.7Ca0.3MnO3 has been investigated. While the ferromagnetic Tc, low field magnetic susceptibility, and insulator‐metal transition are markedly affected by the particle size, the maximum magnetoresistance exhibited by the samples near Tc is not sensitive to the particle size. However, the magnetoresistance at 4.2 K increases with decrease in particle size, suggesting a substantial contribution by the grain boundaries. Preliminary measurements on La0.7Sr0.3MnO3 samples of different particle sizes also corroborate the above conclusions.

Journal ArticleDOI
26 Dec 1996-Nature
TL;DR: In this paper, it was shown that the properties of small metallic particles depend sensitively on whether they have an odd or even number of electrons, and that the combination of quantum size and Coulomb-charging effects strongly influence the thermodynamic properties.
Abstract: THE properties of nanometre-scale metallic particles differ from those of the same material1,2 in bulk. Conduction electrons, because of their wave-like nature, can have only certain discrete values of kinetic energy or wavelength. Such 'quantum-size' effects have been observed in two-dimensional electron gases in semiconductors3,4, and in atomic-scale metallic point contacts5. Also present are 'Coulomb-charging' effects: these are purely classical in origin, and occur when the energy required to add one electron to a conducting sphere exceeds the mean thermal energy kBT. Thermal fluctuations in the total charge on the particle are then suppressed6. In theory, the combination of quantum-size and Coulomb-charging effects should cause the properties of small metallic particles to depend sensitively on whether they have an odd or even number of electrons7. Odd–even effects have been observed in experiments on tunnelling between discrete electronic levels of single metal particles8, but their influence on thermodynamic properties remains to be demonstrated. Here we report measurements of the heat capacity and electronic magnetic susceptibility of small metallic clusters. Our results show definitive evidence for odd–even effects, thus confirming that quantum and classical size effects strongly influence the thermodynamic properties of small particles.

Journal ArticleDOI
TL;DR: This work reports the first study of isolated nanoscale wires with diameters smaller than 100 nm, for which singledomain states could be expected, and obtained unique insight into the process of magnetization reversal by measuring histograms of the switching field as a function of the orientation of the wires in the applied field, their diameter, and the temperature.
Abstract: The mechanisms of magnetization reversal in small magnetic particles have been much discussed in the last decades and prompted intense research activities, motivated in particular by applications in magnetic recording technology [1]. However, experiments were performed, in general, on large assemblies of particles, and the dispersion of morphologies, compositions, orientations, and separations of the magnetic entities limited the interpretation of the results. Furthermore, interactions between particles were difficult to take into account. Single particle studies were possible only in few cases [2]. Recently, insights into the magnetic properties of individual and isolated particles were obtained with the help of near field magnetic force microscopy [3], electron Lorentz microscopy or holography [4], and micro-SQUID (superconducting quantum interference device) magnetometry [5]. It is now possible to make a clear link between experiments performed on nanometer-sized single objects (particles, wires, etc.) and the numerical calculations based on the Brown micromagnetic equations [6]. We report the first study of isolated nanoscale wires with diameters smaller than 100 nm, for which singledomain states could be expected. The cylindrical geometry, with its large shape anisotropy, is well suited for comparison with theory. We obtained unique insight into the process of magnetization reversal by measuring histograms of the switching field as a function of the orientation of the wires in the applied field, their diameter, and the temperature. Furthermore, we measured the probability of switching as a function of the applied field and the temperature. Our studies reveal that the magnetization reversal proceeds by a distortion of the magnetization followed by a nucleation and a propagation process. The observed behavior illustrates the fundamental importance of the study of single, isolated magnetic particles in comparing models and experiments. We developed planar microbridge dc SQUID [7], made of Nb (thickness 20 nm), which were shown to be able to detect 10 4 mB [8]. The SQUID is made of a thin (20 nm) Nb layer in order to prevent flux trapping. The experimental setup allows measurements of hysteresis loops in magnetic fields of up to 0.5 T and temperatures below 6 K, with a time resolution of 100 ms. Ni wires were produced by electrochemically filling the pores of commercially available nanoporous tracketched polycarbonate membranes of thicknesses of 6 to 10 mm [9]. The pore size was chosen in the range of 30 to 100 nm [10]. In order to place one wire on the SQUID detector, we dissolved the membrane in chloroform and put a drop on a chip of some hundreds of SQUID’s. Magnetization measurements were performed on SQUID’s with a single isolated wire. Scanning electron microscopy (SEM) (Fig. 1) was used to determine the position and morphology of the wire. The surface roughness was around 5 nm, corresponding to our SEM resolution.

Journal ArticleDOI
TL;DR: In this article, a methodology is introduced for calculating the deformation response of particulate reinforced metal matrix composites in terms of an effective medium approach combined with the essential features of dislocation plasticity.

Journal ArticleDOI
TL;DR: In this paper, a method for the production of gold nanoparticles with narrow size distributions by reduction of tetrachloroaurate solutions in the presence of thiol-containing organic compounds which self-assemble on the gold surface is described.

Journal ArticleDOI
TL;DR: In this article, the effect of the metal particles on the photoelectrochemical properties of the TiO 2 electrodes was investigated, and the effects of the dispersed metal particles were explained on the basis of the band models.

Journal ArticleDOI
TL;DR: In this article, a comprehensive survey of the previous experimental work, theoretical models, and chemical kinetics studies of single boron particles is presented, along with up-to-date research findings which represent two major research needs strongly recommended by previous researchers.

Journal ArticleDOI
TL;DR: In this article, a coupled transport and reaction model is formulated to investigate the effects of various parameters on biomass pyrolysis, taking into account formation of chars, tars and gases through mechanisms including both primary reactions of virgin biomass degradation and secondary reactions of the primary tar.

Journal ArticleDOI
TL;DR: In this paper, the porosity of mono-sized particles is strongly dependent on both particle shape and packing method, and for a given packing method can be approximately by the proper use of the packing results of cylinders and disks.

Journal ArticleDOI
TL;DR: In this paper, a solgel method was used to obtain monodispersive particles of La0.67Ca0.33MnO3 in the range from 20 to 110 nm at temperatures from 540 to 1000 °C.
Abstract: Using a sol‐gel method we have prepared monodispersive particles of La0.67Ca0.33MnO3 in the range from 20 to 110 nm at temperatures from 540 to 1000 °C. A magnetoresistance above 10% was obtained in a field of 1 kOe for all the particles sizes. These results may be relevant for future applications.

Journal Article
TL;DR: In this article, the authors show that the movement of particles from alveolar spaces into interstitial sites appears to reflect the ability of inhaled ultrafine particle aggregates (TiO2; carbon black) to break down into smaller units, or even singlet particles.
Abstract: Chronic rat inhalation studies have shown that a number of different particle types can induce significant adverse effects, including impaired lung clearance, chronic pulmonary inflammation, pulmonary fibrosis, and lung tumors. These effects occurred when highly insoluble particles of low solubility and low cytotoxicity were inhaled in long-term studies. Inhaled concentrations ranged from a few milligrams per cubic meter up to 250 mg/m3. This wide range of inhaled concentrations may indicate that the particulate compounds have differed largely in their toxicity. This view appears to be supported by the fact that cytotoxic crystalline SiO2 shows very similar effects after much lower inhaled concentrations. However, although administered doses are customarily expressed in units of mass, this may not be the appropriate dose-metric for a correlation with observed effects. For example, effects on alveolar macrophage (AM) mediated clearance of particles could best be correlated with the volumetric lung burden of different particle types, suggesting that the particle volume phagocytized by AM is an appropriate dose parameter for this endpoint. On the other hand, the inflammatory response induced by a number of different particle types could best be correlated with the surface area of the particles retained in the alveolar space. In addition, total surface area of retained particles was the best dose parameter (or a correlation when the endpoint was lung tumors. In all of these studies crystalline SiO2 did not fit into the overall exposure-response or dose-response relationship, clearly demonstrating that SiO2 is a very different (more cytotoxic) particle type. Particle size and surface area can play important roles in the response to inhaled particles, which is especially relevant for ultrafine particles. Inhalation studies with rats exposed to aggregated ultrafine TiO2 and carbon black showed that both compounds induced lung tumors in rats at considerably lower gravimetric lung burdens than larger sized TiO2. However, the different ultrafine particle types did also show differences in the strength of response that cannot be explained by differences in surface area only. Analyses of inhalation studies with ultra fine particles show that the movement of particles from alveolar spaces into interstitial sites appears to reflect the ability of inhaled ultrafine particle aggregates (TiO2; carbon black) to break down into smaller units, or even singlet particles. Further data are needed to evaluate the importance of interstitial cell-particle interactions for the long-term effects. The lung tumor response in rats after chronic high-dose particle inhalation has been suggested to be a rat-specific response that may not be relevant to humans. However, lacking an understanding about mechanistic events, the rat model should not be dismissed prematurely. What should be questioned instead is the relevance of using excessively high exposure concentrations of particles in a rat study. Exposure-response and dose-response relationships for different endpoints indicate the existence of a threshold below which no adverse effects may occur. Such a threshold could be explained by overwhelming specific defense mechanisms in the respiratory tract, such as particle loading of macrophages (prolongation of particle clearance), or limitations of pulmonary antioxidant capacities (inflammatory response). It appears, however, that duration of exposure plays a significant role that can result in a shift of exposure-dose-response relationships and a shift of a threshold when these relationships are compared at the end of a subchronic study versus the end of a chronic study. This shift will cause difficulties for defining a threshold as well as a maximum tolerated dose from results of a subchronic particle inhalation study.

Journal ArticleDOI
TL;DR: In this paper, the authors used a dual-laser aerodynamic particle sizing system to size and track individual particles through the instrument and laser desorption/ionization time-of-flight mass spectrometry to obtain correlated single particle composition data.
Abstract: In this paper, the unique real-time measurement capabilities of aerosol time-of-flight mass spectrometry (ATOFMS) for characterizing atmospheric aerosol particles are demonstrated. ATOFMS is used to obtain the aerodynamic size and chemical composition of individual aerosol particles sampled directly into the instrument from outdoors. Such measurements are made in-situ by combining a unique dual-laser aerodynamic particle sizing system to size and track individual particles through the instrument and laser desorption/ionization time-of-flight mass spectrometry to obtain correlated single particle composition data. At typical ambient concentrations, the size and chemical composition of 50−100 particles per minute can be measured (up to 600 per minute at high particle concentrations). Presented here for the first time are compositionally resolved particle size distributions of ambient aerosol particles, showing definitive size/composition correlations. A goal of these studies is to ultimately couple data obt...

Journal ArticleDOI
TL;DR: In this article, the physical and optical properties of titanium dioxide particulate suspensions in water were investigated for six different commercially available powders, including size of elementary particles, size of particle aggregates in water suspensions, specific surface area, and spectral extin...
Abstract: Precise kinetic studies of photocatalytic reactions in solid catalyst water suspensions require the accurate description of the radiation fieldlight distributioninside the reactor. Solution of the radiative transport equation (RTE) inside the reaction is one of the best ways of accessing to such information. For solving this equation, a minimum of two parameters (the absorption and scattering coefficients) and one scattering spatial distribution function (the phase function) are needed. These attributes are directly associated with the optical behavior of the reacting system and are not independent of catalysts more conventional properties. A complete report on the physical and optical characteristics of titanium dioxide particulate suspensions in water is presented. Results were obtained for six different commercially available powders. The investigated parameters were (i) size of elementary particles, (ii) size of particle aggregates in water suspensions, (iii) specific surface area, (iv) spectral extin...

Journal ArticleDOI
24 Jul 1996-Langmuir
TL;DR: In this paper, the interaction between hydrophilic silica particles and air bubbles in aqueous electrolyte has been studied by colloid probe atomic force microscopy, and the interaction was found to be monotonically repulsive on approach.
Abstract: The interaction between hydrophilic silica particles and air bubbles in aqueous electrolyte has been studied by colloid probe atomic force microscopy. The interaction was found to be monotonically repulsive on approach. The silica surface was also hydrophobized by dehydroxylation and by treatment with octadecyltrichlorosilane (OTS). In these cases a repulsion was observed at long range with an attraction evident as the bubble−particle separation decreased. For a freshly prepared OTS−silica surface the intervening thin film rapidly collapsed, resulting in particle engulfment or establishment of a three-phase line. For an aged OTS−silica surface a stable film was formed which could be ruptured as the loading force was increased. In all cases adhesion resisted bubble−particle separation. This behavior was rationalized in terms of either attractive surface forces or capillary forces and contact angle hysteresis operating after formation of a three-phase line (TPL).

Journal ArticleDOI
TL;DR: In this paper, the experimental results from thermal conductivity measurements show a region of low particle content, 0-12% by volume, where the particles are distributed homogeneously in the polymer matrix and are not interacting with each other.
Abstract: Thermal conductivity and mechanical properties such as tensile strength, elongation at break, and modulus of elasticity of aluminum powder-filled high-density polyethylene composites are investigated experimentally in the range of filler content 0–33% by volume for thermal conductivity and 0–50% by volume for mechanical properties. Experimental results from thermal conductivity measurements show a region of low particle content, 0–12% by volume, where the particles are distributed homogeneously in the polymer matrix and are not interacting with each other; in this region most of the thermal conductivity models for two-phase systems are applicable. At higher particle content, the filler tends to form ag-glomerates and conductive chains resulting in a rapid increase in thermal conductivity. The model developed by Agari and Uno estimates the thermal conductivity in this region. Tensile strength and elongation at break decreased with increasing aluminum particles content, which is attributed to the introduction of discontinuities in the structure. Modulus of elasticity increased up to around 12% volume content of aluminum particles. Einstein's equation, which assumes perfect adhesion between the filler particles and the matrix, explains the experimental results in this region quite well. For particle content higher than 30%, a decrease in the modulus of elasticity is observed which may be attributed to the formation of cavities around filler particles during stretching in tensile tests. © 1996 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: A new approach for the calculation of biological effects of heavy charged particles is discussed, in contrast to other models, the biological effect is determined locally as a function of the local dose deposited by the charged particle tracks.

Journal ArticleDOI
TL;DR: In this article, an experimental study of Al particle combustion in air is presented, in which uniform Al particles were formed and ignited in air using a pulsed micro-arc discharge using a three-wavelength pyrometer, partially burned particles were quenched and cross-sectioned.

Journal ArticleDOI
TL;DR: In this article, the coupled effects of particle size and external heating conditions (reactor heating rate and final temperature) on cellulose pyrolysis were investigated by means of a computer model accounting for all main transport phenomena, variable thermophysical properties and primary, and secondary reaction processes.
Abstract: The coupled effects of particle size and external heating conditions (reactor heating rate and final temperature) on cellulose pyrolysis are investigated by means of a computer model accounting for all main transport phenomena, variable thermophysical properties and primary, and secondary reaction processes. The dynamics of particle conversion are predicted, and final product distributions are favorably compared with experimental measurements. A map is constructed, in terms of particle size as a function of the reactor temperature, to identify the transition from a kinetically controlled conversion to a heat transfer controlled conversion (thermally thin and thermally thick regimes) and from flash to slow-conventional pyrolysis. Conditions for maximizing oil, gas, or char yields are also discussed.