Journal articles: 'Single metal particle'

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Meirer, Florian, Sam Kalirai, Darius Morris, Santosh Soparawalla, Yijin Liu, Gerbrand Mesu, Joy C. Andrews, and Bert M. Weckhuysen. "Life and death of a single catalytic cracking particle." Science Advances 1, no. 3 (April 2015): e1400199. http://dx.doi.org/10.1126/sciadv.1400199.

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Fluid catalytic cracking (FCC) particles account for 40 to 45% of worldwide gasoline production. The hierarchical complex particle pore structure allows access of long-chain feedstock molecules into active catalyst domains where they are cracked into smaller, more valuable hydrocarbon products (for example, gasoline). In this process, metal deposition and intrusion is a major cause for irreversible catalyst deactivation and shifts in product distribution. We used x-ray nanotomography of industrial FCC particles at differing degrees of deactivation to quantify changes in single-particle macroporosity and pore connectivity, correlated to iron and nickel deposition. Our study reveals that these metals are incorporated almost exclusively in near-surface regions, severely limiting macropore accessibility as metal concentrations increase. Because macropore channels are “highways” of the pore network, blocking them prevents feedstock molecules from reaching the catalytically active domains. Consequently, metal deposition reduces conversion with time on stream because the internal pore volume, although itself unobstructed, becomes largely inaccessible.

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Passig, Johannes, Julian Schade, Ellen Iva Rosewig, Robert Irsig, Thomas Kröger-Badge, Hendryk Czech, Martin Sklorz, et al. "Resonance-enhanced detection of metals in aerosols using single-particle mass spectrometry." Atmospheric Chemistry and Physics 20, no. 12 (June 18, 2020): 7139–52. http://dx.doi.org/10.5194/acp-20-7139-2020.

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Abstract. We describe resonance effects in laser desorption–ionization (LDI) of particles that substantially increase the sensitivity and selectivity to metals in single-particle mass spectrometry (SPMS). Within the proposed scenario, resonant light absorption by ablated metal atoms increases their ionization rate within a single laser pulse. By choosing the appropriate laser wavelength, the key micronutrients Fe, Zn and Mn can be detected on individual aerosol particles with considerably improved efficiency. These ionization enhancements for metals apply to natural dust and anthropogenic aerosols, both important sources of bioavailable metals to marine environments. Transferring the results into applications, we show that the spectrum of our KrF-excimer laser is in resonance with a major absorption line of iron atoms. To estimate the impact of resonant LDI on the metal detection efficiency in SPMS applications, we performed a field experiment on ambient air with two alternately firing excimer lasers of different wavelengths. Herein, resonant LDI with the KrF-excimer laser (248.3 nm) revealed iron signatures for many more particles of the same aerosol ensemble compared to the more common ArF-excimer laser line of 193.3 nm (nonresonant LDI of iron). Many of the particles that showed iron contents upon resonant LDI were mixtures of sea salt and organic carbon. For nonresonant ionization, iron was exclusively detected in particles with a soot contribution. This suggests that resonant LDI allows a more universal and secure metal detection in SPMS. Moreover, our field study indicates relevant atmospheric iron transport by mixed organic particles, a pathway that might be underestimated in SPMS measurements based on nonresonant LDI. Our findings show a way to improve the detection and source attribution capabilities of SPMS for particle-bound metals, a health-relevant aerosol component and an important source of micronutrients to the surface oceans affecting marine primary productivity.

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Meirer, F., S. Kalirai, J. Nelson Weker, Y. Liu, J. C. Andrews, and B. M. Weckhuysen. "Agglutination of single catalyst particles during fluid catalytic cracking as observed by X-ray nanotomography." Chemical Communications 51, no. 38 (2015): 8097–100. http://dx.doi.org/10.1039/c5cc00401b.

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X-ray nanotomography of a complete FCC particle cluster reveals increased metal concentrations at the interface of agglutinated E-cat particles, which might play a crucial role E-cat particle clustering.

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Pohl, A., P. G. Reinhard, and E. Suraud. "Towards Single-Particle Spectroscopy of Small Metal Clusters." Physical Review Letters 84, no. 22 (May 29, 2000): 5090–93. http://dx.doi.org/10.1103/physrevlett.84.5090.

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Davis, E. James, and Mark F. Buehler. "Chemical Reactions with Single Microparticles." MRS Bulletin 15, no. 1 (January 1990): 26–33. http://dx.doi.org/10.1557/s088376940006070x.

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Fine particles can be produced via aerosol processes either by means of vapor phase reactions that produce solid or liquid particles or by reactions between a preexisting solid or liquid particle and a reactive gas. This article examines the latter processes because a strong interest has developed in the production of materials via aerosol processing. Although fine particles are frequently produced using flow systems, such as in the laminar flow aerosol reactor of McRae and his co-workers, fundamental studies of the chemical kinetics are more readily done using single microparticles or microdroplets. Design of an aerosol reactor requires knowledge of the reaction rates, for there must be a sufficient residence time of the reacting species in the reactor to complete the desired reaction.Matijević reviewed early work on preparing well-defined and very pure metal oxides by hydrolysis of alkoxide aerosol particles, and Ingebrethsen and co-workers studied the hydrolysis rates of aerosol droplets of aluminum and titanium alkoxides and mixtures of the two alkoxides. Following Matijevic and his colleagues, Okuyama et al. used the thermal decomposition of metal alkoxide vapors to produce ultrafine particles of the oxides of titanium, silicon, and aluminum. The preparation of polymeric aerosols has been studied by Partch et al. and by Ward et al. The latter investigators used single-particle techniques (the electrodynamic balance) to obtain polymerization rate data for the photochemical polymerization of acrylamide monomer microparticles.

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Meyer, D. A., and R. M. Albrecht. "Multiple Labeling for EM using Particles of Different Shape and Metal Composition." Microscopy and Microanalysis 5, S2 (August 1999): 488–89. http://dx.doi.org/10.1017/s1431927600015762.

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Multiple labeling for electron microscopy (EM) is typically accomplished by using colloidal gold (cAu) particles of different sizes. The size distribution of each cAu preparation, which may vary by up to 15%, is the principal factor that limits the number of labels which can be used simultaneously. Furthermore, there is no effective way to use multiple labeling for quantitative, high resolution EM studies. Such analysis requires the use of a single Fab antibody fragment conjugated to a single cAu particle in order to ensure that each particle corresponds to only one antigenic site. Whole antibody molecules cannot be used for quantitative analysis because they are at least divalent, and some, such as dimeric IgA or pentameric IgM, have even more antigen-binding sites. Consequently, it is impossible to deduce whether the presence of one whole antibody molecule corresponds to the presence of one, two, or more targets. Particle diameters ranging from 3 to 5nm are optimal for quantitation because one Fab fragment adsorbs to one particle, more than one Fab fragment may adsorb to a single particle larger than 5nm, and, when smaller than 3nm, several particles may bind to a single Fab fragment.We are evaluating parameters apart from particle size variation to accomplish multiple labeling for both qualitative and quantitative analyses. One method relies on electron energy loss spectroscopy (EELS) to distinguish particles of several metallic compositions, including Au, Ag, Pt, Pd, Rh, and Ru. EELS is performed using a LEO 912 energy filtering transmission electron microscope (EFTEM) with an in-column Omega spectrometer.

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GOODMAN, D. W. "MODEL CATALYSTS: FROM EXTENDED SINGLE CRYSTALS TO SUPPORTED PARTICLES." Surface Review and Letters 02, no. 01 (February 1995): 9–24. http://dx.doi.org/10.1142/s0218625x95000030.

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Model oxide-supported metal catalysts have been prepared by evaporating a metal (e.g., Cu, Pd) onto an oxide ( SiO 2, Al 2 O 3) thin film (~100 Å) which, in turn, is supported on a refractory metal (Mo, W, Ta) surface. The deposited metal films, upon annealing, form small metallic clusters on the oxide surface whose sizes are dependent upon the initial metal film thickness. The surface structures and particle morphologies have been characterized using scanning probe microscopies, temperature programed desorption, X-ray and ultraviolet photoemission, and high-resolution electron energy-loss spectroscopy/infrared reflection-absorption spectroscopy of adsorbed carbon monoxide. The catalytic properties of these particles have also been investigated with respect to several reactions including CO/O 2 and CO/NO. The chemical and electronic properties of the metal particles with respect to size are compared to the analogous properties of extended single-crystal surfaces.

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Dybalska, Agnieszka, Adrian J. Caden, David J. Parker, John Wedderburn, and William D. Griffiths. "Liquid Metal Flow Studied by Positron Emission Tracking." Metallurgical and Materials Transactions B 51, no. 5 (July 6, 2020): 1912–17. http://dx.doi.org/10.1007/s11663-020-01897-7.

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Abstract To improve the properties of castings, a new technique to observe the fluid flow and study the motion of oxygen-bearing inclusions has been developed. This new technique, Positron Emission Particle Tracking (PEPT), enabled a single radioactive tracer particle, moving inside a liquid metal casting, to be tracked with an accuracy of some millimeters, depending on the properties of the liquid metal and the mold. These novel experiments give promising results to observe the liquid metal flow and locate the tracked particle in a casting. Experiments have shown that various particle sizes (200 to 600 μm presented here) can be used to observe the liquid metal flow, if the particle has sufficiently initial radioactivity. Different sizes of particles are considered and their radioactivity compared in terms of their usefulness for tracking in flowing liquid aluminum according to the specific surface area.

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Zhang, Jian, Yi Fu, Mustafa H. Chowdhury, and Joseph R. Lakowicz. "Metal-Enhanced Single-Molecule Fluorescence on Silver Particle Monomer and Dimer: Coupling Effect between Metal Particles." Nano Letters 7, no. 7 (July 2007): 2101–7. http://dx.doi.org/10.1021/nl071084d.

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Venkatesan, Arjun K., Blanca T. Rodríguez, Aurelie R. Marcotte, Xiangyu Bi, Jared Schoepf, James F. Ranville, Pierre Herckes, and Paul Westerhoff. "Using single-particle ICP-MS for monitoring metal-containing particles in tap water." Environmental Science: Water Research & Technology 4, no. 12 (2018): 1923–32. http://dx.doi.org/10.1039/c8ew00478a.

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11

Worringen, A., K. Kandler, N. Benker, T. Dirsch, S. Weinbruch, S. Mertes, L. Schenk, et al. "Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques." Atmospheric Chemistry and Physics Discussions 14, no. 16 (September 8, 2014): 23027–73. http://dx.doi.org/10.5194/acpd-14-23027-2014.

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Abstract. In the present work, three different techniques are used to separate ice-nucleating particles (INP) and ice particle residuals (IPR) from non-ice-active particles: the Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI), which sample ice particles from mixed phase clouds and allow for the analysis of the residuals, as well as the combination of the Fast Ice Nucleus Chamber (FINCH) and the Ice Nuclei Pumped Virtual Impactor (IN-PCVI), which provides ice-activating conditions to aerosol particles and extracts the activated ones for analysis. The collected particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Samples were taken during January/February 2013 at the High Alpine Research Station Jungfraujoch. All INP/IPR-separating techniques had considerable abundances (median 20–70%) of contamination artifacts (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). Also, potential measurement artifacts (soluble material) occurred (median abundance < 20%). After removal of the contamination particles, silicates and Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types separated by all three techniques. Minor types include soot and Pb-bearing particles. Sea-salt and sulfates were identified by all three methods as INP/IPR. Lead was identified in less than 10% of the INP/IPR. It was mainly present as an internal mixture with other particle types, but also external lead-rich particles were found. 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 sampled many submicron particles. Probably owing to the different meteorological conditions, the INP/IPR composition was highly variable on a sample to sample basis. Thus, some part of the discrepancies between the different techniques may result from the (unavoidable) non-parallel sampling. The observed differences of the particles group abundances as well as the mixing state of INP/IPR point to the need of further studies to better understand the influence of the separating techniques on the INP/IPR chemical composition.

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Marinkovic, Nebojsa, and Radoslav Adzic. "Infrared spectroscopy of bare single crystal and nano-particle covered surfaces." Journal of the Serbian Chemical Society 71, no. 8-9 (2006): 945–48. http://dx.doi.org/10.2298/jsc0609945m.

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Infrared spectroelectrochemistry is the leading technique for in situ investigation of electrode - solution interfaces because it can both identify the species adsorbed at the metal/solution interface, and quantitatively follow their reaction and kinetic behavior. The unique capabilities of the method have been demonstrated by selective examples, including the identification of preferentially adsorbed species on single crystal surfaces of noble metals with hexagonal symmetry, and electrochemical oxidation of CO on bare and Pt-decorated single crystal Ru surfaces.

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Dheur, Marie-Christine, Eloïse Devaux, Thomas W. Ebbesen, Alexandre Baron, Jean-Claude Rodier, Jean-Paul Hugonin, Philippe Lalanne, Jean-Jacques Greffet, Gaétan Messin, and François Marquier. "Single-plasmon interferences." Science Advances 2, no. 3 (March 2016): e1501574. http://dx.doi.org/10.1126/sciadv.1501574.

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Surface plasmon polaritons are electromagnetic waves coupled to collective electron oscillations propagating along metal-dielectric interfaces, exhibiting a bosonic character. Recent experiments involving surface plasmons guided by wires or stripes allowed the reproduction of quantum optics effects, such as antibunching with a single surface plasmon state, coalescence with a two-plasmon state, conservation of squeezing, or entanglement through plasmonic channels. We report the first direct demonstration of the wave-particle duality for a single surface plasmon freely propagating along a planar metal-air interface. We develop a platform that enables two complementary experiments, one revealing the particle behavior of the single-plasmon state through antibunching, and the other one where the interferences prove its wave nature. This result opens up new ways to exploit quantum conversion effects between different bosonic species as shown here with photons and polaritons.

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Kolehmainen, J., H. Häkkinen, M. Manninen, and M. Koskinen. "Linear Nuclei: A Density Functional Interpretation." International Journal of Modern Physics E 06, no. 03 (September 1997): 507–13. http://dx.doi.org/10.1142/s0218301397000287.

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We show that linear shape isomers of small even-even nuclei exist with nearly any internucleon interactions. The shapes of the linear isomers look like chains of alpha-particles, but single-particle spectrum reveals that alpha-particle interpretation is not needed. Indeed, the same shapes are obtained even with noninteracting particles in a rectangular cavity. Linear shape isomers are shown to exist also in metal clusters.

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Worringen, A., K. Kandler, N. Benker, T. Dirsch, S. Mertes, L. Schenk, U. Kästner, et al. "Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques." Atmospheric Chemistry and Physics 15, no. 8 (April 22, 2015): 4161–78. http://dx.doi.org/10.5194/acp-15-4161-2015.

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Abstract. 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 200–400 nm in geometric diameter. In a few cases, a second supermicron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the sub-micrometer range. Silicates and Ca-rich particles were mainly found with diameters above 1 μm (using ISI and FINCH), in contrast to the Ice-CVI which also sampled many submicron particles of both groups. Due to changing meteorological conditions, the INP/IPR composition was highly variable if different samples were compared. Thus, the observed discrepancies between the different separation techniques may partly result from the non-parallel sampling. The differences of the particle group relative number abundance as well as the mixing state of INP/IPR clearly demonstrate the need of further studies to better understand the influence of the separation techniques on the INP/IPR chemical composition. Also, it must be concluded that the abundance of contamination artifacts in the separated INP and IPR is generally large and should be corrected for, emphasizing the need for the accompanying chemical measurements. Thus, further work is needed to allow for routine operation of the three separation techniques investigated.

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Yang, Zhi, Zhi-gang Zhang, Ming Guo, and Fang Wang. "ICONE23-1572 SIMULATION OF A SINGLE MOLTEN METAL DROPLET PENETRATING INTO SODIUM POOL USING MOVING PARTICLE SEMI-IMPLICIT METHOD." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2015.23 (2015): _ICONE23–1—_ICONE23–1. http://dx.doi.org/10.1299/jsmeicone.2015.23._icone23-1_268.

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Bhatia, R., and W. A. Sirignano. "Convective burning of a droplet containing a single metal particle." Combustion and Flame 93, no. 3 (May 1993): 215–29. http://dx.doi.org/10.1016/0010-2180(93)90104-b.

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Michael Köhler, J., Danja Kuhfuß, Phillip Witthöft, Martina Hentschel, and Andrea Knauer. "Single-Photon-Single-Electron Transition for Interpretation of Optical Spectra of Nonspherical Metal Nanoparticles in Aqueous Colloidal Solutions." Journal of Nanomaterials 2018 (August 30, 2018): 1–8. http://dx.doi.org/10.1155/2018/1781389.

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Noble metal nanoparticles—especially shape anisotropic particles—have pronounced resonances in the optical spectrum. These sensitive absorption modes attract great interest in various fields of application. For nonspherical particles, no analytic description of the absorption spectra according to the commonly used Mie theory is possible. In this work, we present a semi-empirical approach for the explanation of the optical spectra of shape anisotropic particles such as silver nanoprisms and gold nanorods. We found an interpretation of the optical absorption spectra which is based on a single-photon-single-electron transition. This model is in a better agreement with the basic assumptions of quantum mechanics than the electrodynamic model of a localized surface plasmon excitation. Based on microfluidically obtained Ag nanoprisms and Au nanorods with very high ensemble homogeneities, dependencies between the geometrical properties of the shape anisotropic noble metal nanoparticles and the spectral position of the longitudinal absorption mode could be derived, which show that the assumption of a composed relative permittivity and the inclusion of the Rydberg constant is sufficient to describe the optical properties of the shape anisotropic particles. Within the scope of the measuring accuracy, the calculations furthermore lead to the value of the refractive index of the particle-surrounding medium.

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Moffet, R. C., B. de Foy, L. T. Molina, M. J. Molina, and K. A. Prather. "Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry." Atmospheric Chemistry and Physics 8, no. 16 (August 5, 2008): 4499–516. http://dx.doi.org/10.5194/acp-8-4499-2008.

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Abstract. Continuous ambient measurements with aerosol time-of-flight mass spectrometry (ATOFMS) were made in an industrial/residential section in the northern part of Mexico City as part of the Mexico City Metropolitan Area-2006 campaign (MCMA-2006). Results are presented for the period of 15–27 March 2006. The submicron size mode contained both fresh and aged biomass burning, aged organic carbon (OC) mixed with nitrate and sulfate, elemental carbon (EC), nitrogen-organic carbon, industrial metal, and inorganic NaK inorganic particles. Overall, biomass burning and aged OC particle types comprised 40% and 31%, respectively, of the submicron mode. In contrast, the supermicron mode was dominated by inorganic NaK particle types (42%) which represented a mixture of dry lake bed dust and industrial NaK emissions mixed with soot. Additionally, aluminosilicate dust, transition metals, OC, and biomass burning contributed to the supermicron particles. Early morning periods (2–6 a.m.) showed high fractions of inorganic particles from industrial sources in the northeast, composed of internal mixtures of Pb, Zn, EC and Cl, representing up to 73% of the particles in the 0.2–3μm size range. A unique nitrogen-containing organic carbon (NOC) particle type, peaking in the early morning hours, was hypothesized to be amines from local industrial emissions based on the time series profile and back trajectory analysis. A strong dependence on wind speed and direction was observed in the single particle types that were present during different times of the day. The early morning (3:30–10 a.m.) showed the greatest contributions from industrial emissions. During mid to late mornings (7–11 a.m.), weak northerly winds were observed along with the most highly aged particles. Stronger winds from the south picked up in the late morning (after 11 a.m.), resulting in a decrease in the concentrations of the major aged particle types and an increase in the number fraction of fresh biomass particles. The highest wind speeds were correlated with the highest number fraction of fresh biomass particles (up to 76% of the submicron number fraction) when winds were coming directly from fires that were located south and southeast of the city based on MODIS fire count data. This study provides a unique clock of hourly changes in single particle mixing state and sources as a function of meteorology in Mexico City. These new findings indicate that biomass burning and industrial emissions can make significant contributions to primary particle loadings in Mexico City that are strongly coupled with local meteorology.

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Barber, Angela, Sun Kly, Matthew G. Moffitt, Logan Rand, and James F. Ranville. "Coupling single particle ICP-MS with field-flow fractionation for characterizing metal nanoparticles contained in nanoplastic colloids." Environmental Science: Nano 7, no. 2 (2020): 514–24. http://dx.doi.org/10.1039/c9en00637k.

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Composite particles containing metallic nanoparticles in a polymer matrix, which simulate environmentally-transformed nanoparticles, are effectively characterized by combining field-flow fractionation with single particle ICP-MS.

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Kotsos, B. A., Th E. Liolios, M. E. Grypeos, C. G. Koutroulos, and S. E. Massen. "On a single particle potential for atomic clusters." HNPS Proceedings 9 (February 11, 2020): 307. http://dx.doi.org/10.12681/hnps.2783.

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The single-particle potential V(r) = -Vo[1+(r/K)^β)^-1, which has been proposed in the recent years for atomic (metal) clusters, is studied analytically in the case β = 2. By using perturbation-type techniques, approximate analytic expressions are obtained for the energy eigenvalues and other physically interesting quantities showing the variation of these quantities with the number of valence electrons. The accuracy is tested for Al clusters and is usually very good.

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Pluym, Tammy C., Toivo T. Kodas, Lu-Min Wang, and Howard D. Glicksman. "Silver-palladium alloy particle production by spray pyrolysis." Journal of Materials Research 10, no. 7 (July 1995): 1661–73. http://dx.doi.org/10.1557/jmr.1995.1661.

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Spray pyrolysis was used to produce submicron Ag-Pd metal alloy particles for applications in electronic component fabrication. The particles were prepared in nitrogen carrier gas from metal nitrate precursor solutions with various compositions. The Ag-Pd alloy was the predominant phase for reactor temperatures of 700 °C and above for all compositions. The 70-30 Ag-Pd partcles were fully dense at 700 °C, but an increased reaction temperature was necessary to produce dense particles at higher Pd to Ag ratios. The extent of palladium oxidation was suppressed with increased amounts of Ag. Single-crystal particles could be produced at sufficiently high temperatures. These results show that particle phase composition, size, oxidation behavior, and morphology can be controlled by the Ag-Pd ratio in the precursor solution and by the reaction temperature.

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Chowdhury, F., A. Sowinski, M. Ray, A. Passalacqua, and P. Mehrani. "Charge generation and saturation on polymer particles due to single and repeated particle-metal contacts." Journal of Electrostatics 91 (February 2018): 9–15. http://dx.doi.org/10.1016/j.elstat.2017.11.004.

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Farnsworth, Christine L., Peter O. Newton, Eric Breisch, Michael T. Rohmiller, Jung Ryul Kim, and Behrooz A. Akbarnia. "The Biological Effects of Combining Metals in a Posterior Spinal Implant: In Vivo Model Development Report of the First Two Cases." Advances in Orthopedic Surgery 2014 (February 26, 2014): 1–9. http://dx.doi.org/10.1155/2014/761967.

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Study Design. Combinations of metal implants (stainless steel (SS), titanium (Ti), and cobalt chrome (CC)) were placed in porcine spines. After 12 months, tissue response and implant corrosion were compared between mixed and single metal junctions. Objective. Model development and an attempt to determine any detriment of combining different metals in posterior spinal instrumentation. Methods. Yucatan mini-pigs underwent instrumentation over five unfused lumbar levels. A SS rod and a Ti rod were secured with Ti and SS pedicle screws, SS and Ti crosslinks, SS and CC sublaminar wires, and Ti sublaminar cable. The resulting 4 SS/SS, 3 Ti/Ti, and 11 connections between dissimilar metals per animal were studied after 12 months using radiographs, gross observation, and histology (foreign body reaction (FBR), metal particle count, and inflammation analyzed). Results. Two animals had constructs in place for 12 months with no complications. Histology of tissue over SS/SS connections demonstrated 11.1 ± 7.6 FBR cells, 2.1 ± 1.7 metal particles, and moderate to extensive inflammation. Ti/Ti tissue showed 6.3 ± 3.8 FBR cells, 5.2 ± 6.7 particles, and no to extensive inflammation (83% extensive). Tissue over mixed components had 14.1 ± 12.6 FBR cells and 13.4 ± 27.8 particles. Samples surrounding wires/cables versus other combinations demonstrated FBR (12.4 ± 13.5 versus 12.0 ± 9.6 cells, P = 0.96), particles (19.8 ± 32.6 versus 4.3 ± 12.7, P = 0.24), and inflammation (50% versus 75% extensive, P = 0.12). Conclusions. A nonfusion model was developed to study corrosion and analyze biological responses. Although no statistical differences were found in overlying tissue response to single versus mixed metal combinations, galvanic corrosion between differing metals is not ruled out. This pilot study supports further investigation to answer concerns when mixing metals in spinal constructs.

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Almeida-Júnior, Antonio Alves de, Renata Garcia Fonseca, Isabella Gagliardi Haneda, Filipe de Oliveira Abi-Rached, and Gelson Luis Adabo. "Effect of surface treatments on the bond strength of a resin cement to commercially pure titanium." Brazilian Dental Journal 21, no. 2 (2010): 111–16. http://dx.doi.org/10.1590/s0103-64402010000200004.

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Investigation of the effectiveness of surface treatments that promote a strong bond strength of resin cements to metals can contribute significantly to the longevity of metal-ceramic restorations. This study evaluated the effect of surface treatments on the shear bond strength (SBS) of a resin cement to commercially pure titanium (CP Ti). Ninety cast CP Ti discs were divided into 3 groups (n=30), which received one of the following airborne-particle abrasion conditions: (1) 50 ?m Al2O3 particles; (2) 30 ?m silica-modified Al2O3 particles (Cojet Sand); (3) 110 ?m silica-modified Al2O3 particles (Rocatec). For each airborne-particle abrasion condition, the following post-airborne-particle abrasion treatments were used (n=10): (1) none; (2) adhesive Adper Single Bond 2; (3) silane RelyX Ceramic Primer. RelyX ARC resin cement was bonded to CP Ti surfaces. All specimens were thermally cycled before being tested in shear mode. Failure mode was determined. The best association was Rocatec plus silane. All groups showed 100% adhesive failure. There were combinations that promote higher SBS than the protocol recommended by the manufacturer of RelyX ARC.

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SITKO, PIOTR, and LUCJAN JACAK. "HARTREE–FOCK GROUND STATE OF THE COMPOSITE FERMION METAL." Modern Physics Letters B 09, no. 14 (June 20, 1995): 889–94. http://dx.doi.org/10.1142/s0217984995000851.

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Within the Hartree–Fock approximation the ground state of the composite fermion metal is found. We observe that the single-particle energy spectrum is dominated by the logarithmic interaction exchange term which leads to an infinite jump of the single-particle exchange at the Fermi momentum. It is shown that the Hartree–Fock result brings no corrections to the RPA Fermi velocity.

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Zhang, Jian, Yi Fu, and Joseph R. Lakowicz. "Enhanced Förster Resonance Energy Transfer (FRET) on a Single Metal Particle." Journal of Physical Chemistry C 111, no. 1 (January 2007): 50–56. http://dx.doi.org/10.1021/jp062665e.

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Johnsen, Sten-Egil, Göran Lindbergh, Anton Lundqvist, and Reidar Tunold. "A Single Particle Investigation on the Kinetics of Metal Hydride Materials." Journal of The Electrochemical Society 150, no. 5 (2003): A629. http://dx.doi.org/10.1149/1.1565133.

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Bhatia, R., and W. A. Sirignano. "Transient Heating and Burning of Droplet Containing a Single Metal Particle." Combustion Science and Technology 84, no. 1 (July 1, 1992): 141–61. http://dx.doi.org/10.1080/00102209208951850.

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30

Lee, D., A. Miller, D. Kittelson, and M. R. Zachariah. "Characterization of metal-bearing diesel nanoparticles using single-particle mass spectrometry." Journal of Aerosol Science 37, no. 1 (January 2006): 88–110. http://dx.doi.org/10.1016/j.jaerosci.2005.04.006.

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Elad, Nadav, Giuliano Bellapadrona, Lothar Houben, Irit Sagi, and Michael Elbaum. "Detection of isolated protein-bound metal ions by single-particle cryo-STEM." Proceedings of the National Academy of Sciences 114, no. 42 (October 2, 2017): 11139–44. http://dx.doi.org/10.1073/pnas.1708609114.

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Metal ions play essential roles in many aspects of biological chemistry. Detecting their presence and location in proteins and cells is important for understanding biological function. Conventional structural methods such as X-ray crystallography and cryo-transmission electron microscopy can identify metal atoms on protein only if the protein structure is solved to atomic resolution. We demonstrate here the detection of isolated atoms of Zn and Fe on ferritin, using cryogenic annular dark-field scanning transmission electron microscopy (cryo-STEM) coupled with single-particle 3D reconstructions. Zn atoms are found in a pattern that matches precisely their location at the ferroxidase sites determined earlier by X-ray crystallography. By contrast, the Fe distribution is smeared along an arc corresponding to the proposed path from the ferroxidase sites to the mineral nucleation sites along the twofold axes. In this case the single-particle reconstruction is interpreted as a probability distribution function based on the average of individual locations. These results establish conditions for detection of isolated metal atoms in the broader context of electron cryo-microscopy and tomography.

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Ibrahim, Siti Noorjannah, and Maan M. Alkaisi. "Microelectrode Design for Particle Trapping on Bioanalysis Platform." Advanced Materials Research 1115 (July 2015): 543–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1115.543.

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Microelectrode geometry has significant influence on particles trapping techniques used on bioanalysis platforms. In this paper, the particle trapping patterns of dipole, quadrupole and octupole microelectrode using dielectrophoretic force (DEP) are discussed. The microelectrodes were constructed on a metal-insulator-metal platform, built on a silicon nitride (Si3N4) coated silicon substrate. The back contact is made from 20 nm nickel-chromium (NiCr) and 100 nm gold (Au) as the first layer. Then, SU-8-2005 (negative photoresist) is used on the second layer to create microcavities for trapping the particles. The third layer, where the three geometries were patterned, is made from 20 nm NiCr and 100 nm Au layers. Prior to fabrication, the particles trapping patterns of the microelectrodes were profiled using a finite element software, COMSOL 3.5a. Trapping patterns for the three geometries were evaluated using polystyrene latex microbeads. Results from the experiment validate simulation studies in term of microelectrode trapping ability up to single particle efficiency. It provides the potential of converting the trapping platform into a lab-on-chip system.

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IWAMA, SABURO, and KAZUHIRO MIHAMA. "GROWTH OF In-Sb FINE PARTICLES BY FLOWING-GAS EVAPORATION TECHNIQUE." Surface Review and Letters 03, no. 01 (February 1996): 49–53. http://dx.doi.org/10.1142/s0218625x96000127.

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Fine particles of the In-Sb system were prepared by the FGE technique (flowing-gas evaporation technique). The characteristic of the technique is that the formation of the vapor zone and particle growth zone along the flow of inert gas can be controlled by the inert-gas species and the flow velocity. From single-source evaporations, In fine islands grown on the amorphous carbon in the metal vapor zone showed a fiber structure with [111] and [001] fiber axes. In the particle growth zone In fine particles were formed, showing very frequently a characteristic contrast in them due to a lattice defect. Sb fine particles showed amorphous structure. These results may be attributed to the enhanced quenching effect of the FGE technique, already observed in the ordinary gas-evaporation technique. By coevaporation of In and Sb, granular film grew in the metal vapor zone, and fine particles were formed in the particle growth zone. The crystal structure was assigned to be the zincblende type including the wurtzite type of intermetallic compound InSb.

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34

Zhang, G., X. Bi, N. Qiu, B. Han, Q. Lin, L. Peng, D. Chen, et al. "The real part of the refractive indices and effective densities for chemically segregated ambient aerosols in Guangzhou by a single particle aerosol mass spectrometer." Atmospheric Chemistry and Physics Discussions 15, no. 23 (December 10, 2015): 34647–72. http://dx.doi.org/10.5194/acpd-15-34647-2015.

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Abstract. Microphysical properties of atmospheric aerosols are essential to better evaluate their radiative forcing. This paper first presents an estimate of the real part of the refractive indices (n) and effective densities (ρeff) of chemically segregated atmospheric aerosols in China. Vacuum aerodynamic diameter, chemical compositions, and light scattering intensities of individual particles were simultaneously measured by a single particle aerosol mass spectrometer (SPAMS) during fall of 2012 in Guangzhou. On the basis of Mie theory, n and ρeff were estimated for 17 particle types in four categories: organics (OC), elemental carbon (EC), internally mixed EC and OC (ECOC), and metal rich, respectively. Results indicate the presence of spherical or nearly spherical shape for majority of particle types, whose partial scattering cross section vs. sizes were well fitted to Mie theoretical modeling results. While sharing n in a narrow range (1.47–1.53), majority of particle types exhibited a wide range of ρeff (0.87–1.51 g cm−3). OC group is associated with the lowest ρeff (0.87–1.07 g cm−3), while metal rich group with the highest ones (1.29–1.51 g cm−3). It is noteworthy that a specific EC type exhibits a complex scattering curve vs. size due to the presence of both compact and irregularly shape particles. Overall, the results on detailed relationship between physical and chemical properties benefits future researches on the impact of aerosols on visibility and climate.

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35

Karhunen, T., A. Lähde, J. Leskinen, R. Büchel, O. Waser, U. Tapper, and J. Jokiniemi. "Transition Metal-Doped Lithium Titanium Oxide Nanoparticles Made Using Flame Spray Pyrolysis." ISRN Nanotechnology 2011 (December 29, 2011): 1–6. http://dx.doi.org/10.5402/2011/180821.

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Defect spinel phase lithium titanate (Li4Ti5O12) has been suggested as a promising negative electrode material for next generation lithium ion batteries. However, it suffers from low electrical conductivity. To overcome this problem conduction path length can be reduced by decreasing the primary particle size. Alternatively the bulk conductivity of Li4Ti5O12 can be increased by doping it with a conductive additive. In this paper a steady, single-step gas-phase technique for lithium titanate synthesis that combines both approaches is described. The process is used to produce doped Li4Ti5O12 nanoparticles with primary particle size of only 10 nm. The product is found to consist of single-crystalline nanoparticles with high phase and elemental purity. Two dopant materials are tested and found to behave very differently. The silver dopant forms a separate phase of nanometre-sized particles of metallic silver which agglomerate with Li4Ti5O12. The copper dopant, on the other hand, reacts with the lithium titanate to form a double spinel phase of Li3(Li1−2xCu3xTi5−x)O12.

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Harris, E., B. Sinha, D. van Pinxteren, J. Schneider, L. Poulain, J. Collett, B. D'Anna, et al. "In-cloud sulfate addition to single particles resolved with sulfur isotope analysis during HCCT-2010." Atmospheric Chemistry and Physics Discussions 14, no. 2 (January 28, 2014): 2935–81. http://dx.doi.org/10.5194/acpd-14-2935-2014.

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Abstract. In-cloud production of sulfate modifies the aerosol size distribution, with important implications for the magnitude of indirect and direct aerosol cooling and the impact of SO2 emissions on the environment. We investigate which sulfate sources dominate the in-cloud addition of sulfate to different particle classes as an air parcel passes through an orographic cloud. Sulfate aerosol, SO2 and H2SO4 were collected upwind, in-cloud and downwind of an orographic cloud for three cloud measurement events during the Hill Cap Cloud Thuringia campaign in Autumn, 2010 (HCCT-2010). Combined SEM and NanoSIMS analysis of single particles allowed the δ34S of particulate sulfate to be resolved for particle size and type. The most important in-cloud SO2 oxidation pathway at HCCT-2010 was aqueous oxidation catalysed by transition metal ions (TMI catalysis), which was shown with single particle isotope analyses to occur primarily in cloud droplets nucleated on coarse mineral dust. In contrast, direct uptake of H2SO4(g) and ultrafine particulate were the most important sources modifying fine mineral dust, increasing its hygroscopicity and facilitating activation. Sulfate addition to "mixed" particles (secondary organic and inorganic aerosol) and coated soot was dominated by in-cloud aqueous SO2 oxidation by H2O2 and direct uptake of H2SO4(g) and ultrafine particle sulfate, depending on particle size mode and time of day. These results provide new insight into in-cloud sulfate production mechanisms, and show the importance of single particle measurements and models to accurately assess the environmental effects of cloud processing.

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Harris, E., B. Sinha, D. van Pinxteren, J. Schneider, L. Poulain, J. Collett, B. D'Anna, et al. "In-cloud sulfate addition to single particles resolved with sulfur isotope analysis during HCCT-2010." Atmospheric Chemistry and Physics 14, no. 8 (April 28, 2014): 4219–35. http://dx.doi.org/10.5194/acp-14-4219-2014.

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Abstract. In-cloud production of sulfate modifies aerosol size distribution, with important implications for the magnitude of indirect and direct aerosol cooling and the impact of SO2 emissions on the environment. We investigate which sulfate sources dominate the in-cloud addition of sulfate to different particle classes as an air parcel passes through an orographic cloud. Sulfate aerosol, SO2 and H2SO4 were collected upwind, in-cloud and downwind of an orographic cloud for three cloud measurement events during the Hill Cap Cloud Thuringia campaign in autumn 2010 (HCCT-2010). Combined SEM and NanoSIMS analysis of single particles allowed the δ34S of particulate sulfate to be resolved for particle size and type. The most important in-cloud SO2 oxidation pathway at HCCT-2010 was aqueous oxidation catalysed by transition metal ions (TMI catalysis), which was shown with single particle isotope analyses to occur primarily in cloud droplets nucleated on coarse mineral dust. In contrast, direct uptake of H2SO4 (g) and ultrafine particulate were the most important sources modifying fine mineral dust, increasing its hygroscopicity and facilitating activation. Sulfate addition to "mixed" particles (secondary organic and inorganic aerosol) and coated soot was dominated by in-cloud aqueous SO2 oxidation by H2O2 and direct uptake of H2SO4 (g) and ultrafine particle sulfate, depending on particle size mode and time of day. These results provide new insight into in-cloud sulfate production mechanisms, and show the importance of single particle measurements and models to accurately assess the environmental effects of cloud processing.

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38

Mazumder, Quamrul H. "Prediction of Erosion Due to Solid Particle Impact in Single-Phase and Multiphase Flows." Journal of Pressure Vessel Technology 129, no. 4 (September 14, 2006): 576–82. http://dx.doi.org/10.1115/1.2767336.

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Solid particle erosion of metal surfaces is a major problem in several fluid handling industries due to unpredicted equipment failure and production loss. The prediction of erosion is difficult even in a single-phase flow. The complexity of the problem increases significantly in a multiphase flow due to the existence of different flow patterns where the spatial distribution of the phases changes with the change of phase flow rates. Earlier predictive means of erosion in single and multiphase flows were primarily based on empirical data and were limited to the flow conditions of the experiments. A mechanistic model has been developed for predicting erosion in single-phase and multiphase flows considering the effects of solid particle impact velocities that cause erosion. Local fluid velocities and simplified equations are used to calculate erosion rates assuming a uniform distribution of solid particles in the liquid phase in the multiphase flow. Another assumption was that the solid particle velocities are similar to the velocity of the fluids surrounding the particles. As the model is based on the physics of multiphase flow and erosion phenomenon, it is more general than the previous models. The predicted erosion rates obtained by the mechanistic model are compared to experimental data available in the literature showing a reasonably good agreement.

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39

De Angelis, R. J., A. G. Dhere, M. A. Maginnis, P. J. Reucroft, G. E. Ice, and A. Habenschuss. "Synchrotron X-Ray Scattering for the Structural Characterization of Catalysts." Advances in X-ray Analysis 30 (1986): 389–94. http://dx.doi.org/10.1154/s0376030800021534.

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Discussions exist in the literature concerning the application of single x-ray diffraction profile analysis to determine the average particle size, particle size distribution and root mean squared strain in catalytic systems. Nandi et al. have shown that the single order analysis can give erroneous strain results and is subject to error in the large particle size range. They further indicated that the initial slope of Stokes corrected Fourier coefficients gives more reliable average p article size than that which is calculated from single order peak shape analysis. There is apparent agreement that the average particle size and the particle size distribution measured by single order profile analysis, in small metal particle systems, are reliable.

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40

Zhang, Guohua, Xinhui Bi, Ning Qiu, Bingxue Han, Qinhao Lin, Long Peng, Duohong Chen, et al. "The real part of the refractive indices and effective densities for chemically segregated ambient aerosols in Guangzhou measured by a single-particle aerosol mass spectrometer." Atmospheric Chemistry and Physics 16, no. 4 (March 3, 2016): 2631–40. http://dx.doi.org/10.5194/acp-16-2631-2016.

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Abstract. Knowledge on the microphysical properties of atmospheric aerosols is essential to better evaluate their radiative forcing. This paper presents an estimate of the real part of the refractive indices (n) and effective densities (ρeff) of chemically segregated atmospheric aerosols in Guangzhou, China. Vacuum aerodynamic diameter, chemical compositions, and light-scattering intensities of individual particles were simultaneously measured by a single-particle aerosol mass spectrometer (SPAMS) during the fall of 2012. On the basis of Mie theory, n at a wavelength of 532 nm and ρeff were estimated for 17 particle types in four categories: organics (OC), elemental carbon (EC), internally mixed EC and OC (ECOC), and Metal-rich. The results indicate the presence of spherical or nearly spherical shapes for the majority of particle types, whose partial scattering cross-section versus sizes were well fitted to Mie theoretical modeling results. While sharing n in a narrow range (1.47–1.53), majority of particle types exhibited a wide range of ρeff (0.87–1.51 g cm−3). The OC group is associated with the lowest ρeff (0.87–1.07 g cm−3), and the Metal-rich group with the highest ones (1.29–1.51 g cm−3). It is noteworthy that a specific EC type exhibits a complex scattering curve versus size due to the presence of both compact and irregularly shaped particles. Overall, the results on the detailed relationship between physical and chemical properties benefits future research on the impact of aerosols on visibility and climate.

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41

Gagliano, E. R., A. A. Aligia, Liliana Arrachea, and Michel Avignon. "Single-particle spectral function of a generalized Hubbard model: Metal-insulator transition." Physical Review B 51, no. 20 (May 15, 1995): 14012–19. http://dx.doi.org/10.1103/physrevb.51.14012.

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42

Yannouleas, C., and R. A. Broglia. "Collective and single-particle aspects in the optical response of metal microclusters." Physical Review A 44, no. 9 (November 1, 1991): 5793–802. http://dx.doi.org/10.1103/physreva.44.5793.

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43

TRIVEDI, NANDINI, YEN LEE LOH, KARIM BOUADIM, and MOHIT RANDERIA. "ASPECTS OF LOCALIZATION ACROSS THE 2D SUPERCONDUCTOR-INSULATOR TRANSITION." International Journal of Modern Physics: Conference Series 11 (January 2012): 22–37. http://dx.doi.org/10.1142/s2010194512006137.

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It is well known that the metal-insulator transition in two dimensions for non-interacting fermions takes place at infinitesimal disorder. In contrast, the superconductor-to-insulator transition takes place at a finite critical disorder (on the order of Vc ~ 2t), where V is the typical width of the distribution of random site energies and t is the hopping scale. In this article we compare the localization/delocalization properties of one and two particles. Whereas the metal-insulator transition is a consequence of single-particle Anderson localization, the superconductor-insulator transition (SIT) is due to pair localization – or, alternatively, fluctuations of the phase conjugate to pair density. The central question we address is how superconductivity emerges from localized single-particle states. We address this question using inhomogeneous mean field theory and quantum Monte Carlo techniques and make several testable predictions for local spectroscopic probes across the SIT. We show that with increasing disorder, the system forms superconducting blobs on the scale of the coherence length embedded in an insulating matrix. In the superconducting state, the phases on the different blobs are coherent across the system whereas in the insulator long-range phase coherence is disrupted by quantum fluctuations. As a consequence of this emergent granularity, we show that the single-particle energy gap in the density of states survives across the transition, but coherence peaks exist only in the superconductor. A characteristic pseudogap persists above the critical disorder and critical temperature, in contrast to conventional theories. Surprisingly, the insulator has a two-particle gap scale that vanishes at the SIT despite a robust single-particle gap.

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Yuan, Rui, Sudhanshu S. Singh, Xiao Liao, Jay Oswald, and Nikhilesh Chawla. "Fracture Analysis of Particulate Metal Matrix Composite Using X-ray Tomography and Extended Finite Element Method (XFEM)." Journal of Composites Science 4, no. 2 (May 30, 2020): 62. http://dx.doi.org/10.3390/jcs4020062.

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Particle reinforced metal matrix composites (MMCs) offer high strength, low density, and high stiffness, while maintaining reasonable cost. The damage process in these MMCs starts with either the fracture of particles or by the de-cohesion of the particle-matrix interfaces. In this study, the extended finite elements method (XFEM) has been used in conjunction with X-ray synchrotron tomography to study fracture mechanisms in these materials under tensile loading. The initial 3D reconstructed microstructure from X-ray tomography has been used as a basis for the XFEM to simulate the damage in the 20 vol.% SiC particle reinforced 2080 aluminum alloy composite when tensile loading is applied. The effect of mesh sensitivity on the Weibull probability has been studied based on a single sphere and several particles with realistic geometries. Additionally, the effect of shape and volume of particles on the Weibull fracture probability was studied. The evolution of damage with the applied traction has been evaluated using simulation and compared with the experimental results obtained from in situ tensile testing.

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Tang, Henry H. K., and Kenneth P. Rodbell. "Single-Event Upsets in Microelectronics: Fundamental Physics and Issues." MRS Bulletin 28, no. 2 (February 2003): 111–16. http://dx.doi.org/10.1557/mrs2003.37.

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AbstractWe review the current understanding of single-event upsets (SEUs) in microelectronic devices. In recent years, SEUs have been recognized as one of the key reliability concerns for both current and future technologies. We identify the major sources of SEUs that impact many commercial products: (1) alpha particles in packaging materials, (2) background radiation due to cosmic rays, and (3) thermal neutrons in certain device materials. The origins of SEUs are examined from the standpoint of the fundamental atomic and nuclear interactions between the intruding particles (alpha particles, cosmic rays, and thermal neutrons) and semiconductor materials. We analyze field funneling, which is a key mechanism of charge collection in a device struck by an ionizing particle. Next, we formulate how SEU cross sections and SEU rates are calculated and discuss how these basic quantities are related to experiments. Finally, we summarize the major SEU issues regarding modeling, bulk complementary metal oxide semiconductor technologies, and research on future, exploratory technologies.

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Göbel, K., and F. Wahl. "Electron Density Distribution of a Single Hydrogen Perturbation in a Metal Lattice." Zeitschrift für Naturforschung A 42, no. 5 (May 1, 1987): 431–37. http://dx.doi.org/10.1515/zna-1987-0501.

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The electronic structure of hydrogen centres stored in a metal crystal is described by a microscopic theory based on a functional energy difference method. That formalism works in a suitably chosen tensor product space built on a physical quasi-particle vacuum state. A transformation back to a bare Fock space representation is shown. This transformation operator divides the functional eigenvalue equation into a difference of two Schrödinger problems. The resulting state vectors can be used to calculate the electronic density distribution of a hydrogen excess electron in a metal lattice. The density function is obtained in a higher order approximation which considers the influence of three-particle correlations. A numerical solution is discussed for the case of a single hydrogen centre in a magnesium crystal. The plot shows that the excess electron is mainly localized in the surroundings of the corresponding hydrogen core. But with increasing host lattice extension there is more and more a non-vanishing probability to find the hydrogen electron dipped into the Fermi sea of metal electrons.

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47

Zorin, Alexander V. "Kuryshkin-Wodkiewicz quantum measurement model for alkaline metal atoms." Discrete and Continuous Models and Applied Computational Science 28, no. 3 (December 15, 2020): 274–88. http://dx.doi.org/10.22363/2658-4670-2020-28-3-274-288.

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The constructive form of the Kuryshkin-Wodkiewicz model of quantum measurements was earlier developed in detail for the quantum Kepler problem. For more complex quantum objects, such a construction is unknown. At the same time, the standard (non-constructive) model of Holevo-Helstrom quantum measurements is suitable for any quantum object. In this work, the constructive model of quantum measurements is generalized to a wider class of quantum objects, i.e., the optical spectrum of atoms and ions with one valence electron. The analysis is based on experimental data on the energy ordering of electrons in an atom according to the Klechkovsky-Madelung rule and on the substantiation of a single-particle potential model for describing the energy spectrum of optical electrons in alkali metal atoms. A representation of the perturbation of a single-particle potential in the form of a convolution of the potential of an electron in a hydrogen atom with the Wigner function of a certain effective state of the core in an alkali metal atom representation allows reducing all calculation algorithms for alkali metals to the corresponding algorithms for the hydrogen atom.

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48

Laghari, Rashid Ali, Jianguang Li, and Yongxiang Wu. "Study of Machining Process of SiCp/Al Particle Reinforced Metal Matrix Composite Using Finite Element Analysis and Experimental Verification." Materials 13, no. 23 (December 3, 2020): 5524. http://dx.doi.org/10.3390/ma13235524.

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In this paper, a two-dimensional orthogonal cutting simulation model of SiCp/Al composite was established. The geometry and material constitutive model of the particle, the matrix, and the interface layer have been modeled respectively. In view of the distribution of the particles in the matrix, this paper proposed respectively a two-dimensional particle random distribution to simulate particles randomly distributed in the matrix. Then, the cutting state of SiC reinforced particles was analyzed, the novel approach was adopted the geometric shapes of SiC particles in this study is taken as an oval shape. Three different locations of SiC particle relative to the cutting tool path were simulated to analyze the cutting state such as particle removal. The interface layer was introduced to the case that the particle was on the cutting path to study the influence on the stress and strain transfer. Through the post-processing of simulation results, the influence of interface property on the composite reinforcement effect was studied quantificationally. Finally, the cutting process of SiCp/Al composite material was simulated. This paper studied the influence on the machined surface morphology, chip morphology, stress distribution, and cutting force of many factors of the cutting speed and the cutting thickness. The single factor orthogonal cutting experiment was designed the influence of cutting speed and feed rate on the cutting force. The cutting force results of the experiment and the simulation were compared through the deviation analysis, which verified the simulation model.

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Nöthe, Michael, Matthias Schulze, Rainer Grupp, Bernd Kieback, and A. Haibel. "Investigation of Sintering of Spherical Copper Powder by Micro Focus Computed Tomography (μCT) and Synchrotron Tomography." Materials Science Forum 539-543 (March 2007): 2657–62. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.2657.

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The two-particle model describes the approach of particle centres and the growth of the interparticle contacts during sintering of metal powders. Unfortunately the comprehensive description of processes inside of three dimensional specimens must consider the contribution of particle rearrangements. The recent developments of combined micro focus computed tomography (CT) and 3D photogrammetric image analyzing give the opportunity to obtain the experimental data required to overcome the shortcomings of sintering theories based on the two-particle model. The analysis of spherical poly and single crystalline copper powder was performed by CT. In addition a single crystal specimen was analyzed by high resolution synchrotron radiation tomography - a more sophisticated analysis method with very limited availability. The analysis of the 3D tomographic image by photogrammetric image analyzing yielded the positions and radii of all particles and their contact partners as well. A statistical analysis of the retrieved data was performed. The formation and breaking of necks during sintering could be observed. An in-depth analysis of the particle rotation with respect to the coordination number and local density will be presented.

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Zemlianov, A. V., E. P. Evtushenko, and R. R. Balokhonov. "Numerical simulation of deformation and fracture of metal-matrix composites with considering residual stresses." PNRPU Mechanics Bulletin, no. 4 (December 15, 2020): 86–96. http://dx.doi.org/10.15593/perm.mech/2020.4.08.

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Thermomechanical behavior of metal-matrix composite materials is investigated. Boron carbide B4C and high-strength aluminum alloy 6061-T6 are used as strengthening particle and matrix materials, respectively. Microstructure of the metal-matrix composite takes into account the complex shape of particles explicitly. Isotropic elastoplastic and elastic-brittle models were used to simulate the mechanical response of the aluminum matrix and ceramic particles, respectively. To investigate the crack initiation and propagation in ceramic particles, a Huber type fracture criterion was chosen that takes into account the type of the local stress state in ceramic materials: bulk tension or compression. The composite material with a single particle of both the really observed in the experiment and ideally round shapes is considered. The influence of the residual thermal stresses arising during cooling of the composite material from the temperature of aluminum recrystallization to the room temperature on the character of plastic strain localization in the aluminum matrix and fracture of carbide particles and on the macroscopic strength of the composite under external tension or compression is studied numerically. Two-dimensional dynamic boundary value problems in the plane-stress and plane-strain formulations were solved numerically by the finite element method using the Explicit module of the Abaqus software package. VUMAT subroutine procedures incorporating the constitutive models were developed and integrated into the Abaqus solver. Based on the results of the numerical simulation, it was concluded that the residual thermal stresses arising during cooling lead to the change in the mechanism of the particle fracture from in-particle cracking to debonding and increase the strength of the composite subjected to tension after the cooling.

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Journal articles on the topic 'Single metal particle'

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