Academic literature on the topic 'Single metal particle'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Single metal particle.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Single metal particle"
1
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.
Full textAbstract:
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.
2
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.
Full textAbstract:
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.
3
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.
Full textAbstract:
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.
4
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.
Full text
5
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.
Full textAbstract:
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.
6
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.
Full textAbstract:
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.
7
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.
Full textAbstract:
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.
8
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.
Full textAbstract:
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.
9
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.
Full text
10
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.
Full textDissertations / Theses on the topic "Single metal particle"
1
Kempa, Thomas. "Towards Implementation of Metal Nanoclusters as Luminescent Probes for Detection of Single-Particle Dynamics: "Watching Nanoscale Dynamics Unfold"." Thesis, Boston College, 2004. http://hdl.handle.net/2345/442.
Full textAbstract:
Thesis advisor: John T. FourkasOne can extract a tremendous amount of information about the organizational and dynamic states of molecules, in situ and in real-time, through highly sensitive and noninvasive single particle optical probing. The highly efficient, multi-photon excited luminescence from stabilized metal nanoclusters renders these species useful as optical probes that can be used in detecting single particle and molecular dynamics. We generate stable, and monodisperse samples of Ag nanoclusters as small as 1 nm in diameter, and find that through substitution of various stabilizer molecules we can precisely tune the size of the clusters over a 1-6 nm range of diameters, ensuring monodispersity and stability at every stage. These clusters also exhibit highly efficient, polarized luminescence upon two photon excitation at 800 nm and remain highly photostable, not exhibiting the deleterious blinking that occurs with many single-molecule fluorophores. In order to demonstrate the utility of these clusters as single-molecule probes, we track their emission polarization over long periods in deeply supercooled liquids such as 4'(octahydro-4,7-methano-5H-inden-5-yliden) bisphenol dimethyl ether (ODE). Our results suggest that these clusters can detect nanoscale dynamics with high sensitivity
Thesis (BS) — Boston College, 2004
Submitted to: Boston College. College of Arts and Sciences
Discipline: Chemistry
Discipline: College Honors Program
2
Olk, Phillip. "Optical Properties of Individual Nano-Sized Gold Particle Pairs." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1218612352686-00553.
Full textAbstract:
This thesis examines and exploits the optical properties of pairs of MNPs. Pairs of MNPs offer two further parameters not existent at single MNPs, which both affect the local optical fields in their vicinity: the distance between them, and their relative orientation with respect to the polarisation of the excitation light. These properties are subject of three chapters: One section examines the distance-dependent and orientation-sensitive scattering cross section (SCS) of two equally sized MNPs. Both near- and far-field interactions affect the spectral position and spectral width of the SCS. Far-field coupling affects the SCS even in such a way that a two-particle system may show both a blue- and redshifted SCS, depending only on the distance between the two MNPs. The maximum distance for this effect is the coherence length of the illumination source – a fact of importance for SCS-based experiments using laser sources. Another part of this thesis examines the near-field between two MNPs and the dependence of the locally enhanced field on the relative particle orientation with respect to the polarisation of the excitation light. To attain a figure of merit, the intensity of fluorescence light from dye molecules in the surrounding medium was measured at various directions of polarisation. The field enhancement was turned into fluorescence enhancement, even providing a means for sensing the presence of very small MNPs of 12 nm in diameter. In order to quantify the near-field experimentally, a different technique is devised in a third section of this thesis – scanning particle-enhanced Raman microscopy (SPRM). This device comprises a scanning probe carrying an MNP which in turn is coated with a molecule of known Raman signature. By manoeuvring this outfit MNP into the vicinity of an illuminated second MNP and by measuring the Raman signal intensity, a spatial mapping of the field enhancement was possibleDiese Dissertation untersucht und nutzt die optischen Eigenschaften von Paaren von Metall-Nanopartikeln (MNP). MNP-Paare bieten gegenüber einzelnen MNP zwei weitere Parameter, welche beide auf das optische Nahfeld der zwei MNPs wirken: zum Einen der Abstand der zwei MNPs zueinander, zum Anderen die relative Ausrichtung des Paares bezüglich der Polarisation des anregenden Lichts. Diese Eigenschaften sind Thema der Arbeit: Ein Abschnitt untersucht den abstands- und orientierungsabhängigen Streuquerschnitt (SQS) zweier gleichgroßer MNPs. Die spektrale Position und die Breite des SQS wird von Wechselwirkungen sowohl im Nah- als auch im Fernfeld beeinflusst. Der Einfluß der Fernfeld-Wechselwirkung geht so weit, daß ein Zwei-MNP-System sowohl einen blau- als auch einen rotverschobenen SQS haben kann – dies hängt lediglich vom Abstand der zwei MNPs ab. Die Reichweite dieser Fernfeld-Wechselwirkung wird durch die Kohärenzlänge der Beleuchtungsquelle bestimmt – eine wichtige Tatsache für SQS-Untersuchungen, welche Laserquellen verwenden. Ein weiterer Teil der Dissertation untersucht das Nahfeld zwischen zwei MNPs. Insbesondere wird dargestellt, inwieweit die Überhöhung des Nahfelds von der Orientierung des Partikelpaares bezüglich der Polarisation des Anregungslichts abhängt. Um den Effekt quantifizieren zu können, wurde die Intensität der Fluoreszenz des umgebenden Mediums für verschiedene Polarisationsrichtungen gemessen. Die lokale Feldverstärkung konnte in eine Fluoreszenzverstärkung gewandelt werden, mit deren Hilfe sich sogar die Anwesenheit sehr kleiner MNPs von nur 12 nm Durchmesser nachweisen ließ. Wie Nahfeld-Intensitäten experimentell quantifiziert werden können, stellt ein dritter Abschnitt dieser Dissertation vor – per MNP-verstärkter Raman-Rastersonden-Mikroskopie. Diese Technik besteht aus einer Rastersonde, welcher ein MNP anheftet, welches wiederum mit einem Molekül bekannter Ramansignatur überzogen ist. Indem solch eine Sonde in die unmittelbare Nähe eines zweiten, beleuchteten MNPs gebracht wurde und dabei die Intensität des Raman-Signals aufgezeichnet wurde, ließ sich die räumliche Verteilung der Ramanverstärkung vermessen
3
Patty, Mark R. Montfrooij Wouter T. "Single particle dynamics in liquid metals." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6166.
Full textAbstract:
Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 17, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Wouter Montfrooij. Vita. Includes bibliographical references.
4
Rai, Chandrakant. "Computational model of ductile erosion by single particle impact." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1735.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains v, 90 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 78-80).
5
Li, Shiwen. "Metal nanoparticles encapsulated in membrane-like zeolite single crystals : application to selective catalysis." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10057/document.
Full textAbstract:
Les matériaux « coeur-coquille » composés d’une nanoparticule métallique encapsulée à l'intérieur de coquilles inorganiques (oxydes, carbone …) attirent de plus en plus l'attention par leurs propriétés particulières, en particulier dans le domaine de la catalyse. Les particules métalliques sont protégées par la coquille, qui empêche entre autres le frittage et la croissance des particules à haute température. Cependant, les coquilles sont généralement méso à macroporeuses et elles ne peuvent pas jouer le rôle de tamis moléculaire pour les molécules de taille nanométrique. En revanche, les zéolithes sont des solides cristallins microporeux dont les pores bien définis permettent une forte discrimination des réactifs basée sur la taille, la forme ou leur coefficient de diffusion. L’objectif de cette thèse visait à la synthèse de catalyseurs de type coeur-coquille dans lesquels la coquille est une zéolite microporeuse de structure MFI (silicalite-1 et ZSM-5), le coeur étant soit une particule de métal noble (Au, Ag, Pt, Pd), soit des alliages de ces différents métaux, soit enfin un métal de transition (Co, Ni, Cu). Ces catalyseurs ont été appliqués dans des réactions d'hydrogénation sélective (aromatiques substitués) et l'oxydation sélective de CO en présence d'hydrocarbures. Nous avons ainsi montré que la coquille zéolithique, tout en protégeant les particules du frittage, modifie la sélectivité des réactions en interdisant aux réactifs volumineux d’atteindre les sites catalytiquesNanostructured yolk-shell materials, which consist of metal nanoparticle cores encapsulated inside hollow shells, attract more and more attention in material science and catalyst applications during the last two decades. Metal particles are usually highly mono-dispersed in size and isolated from each other by the shell, which prevents growth by sintering at high temperature. Because they are generally made of meso/macroporous oxides or amorphous carbon, shells cannot carry out molecular sieve-type separation of molecules at the nanometric scale. The aim of the present thesis was to synthesize yolk-shell catalyst with microporous zeolite shells (silicalite-1 and ZSM-5), containing noble (Au, Pt, Pd) transition (Co, Ni, Cu) and alloy metal nanoparticles. Zeolites are crystalline microporous solids with well-defined pores capable of discriminating nanometric reactants on the basis of size, shape and diffusion rate. Zeolite-based yolk-shell catalysts have been applied in selective hydrogenation (toluene and mesitylene) and oxidation (CO) reactions in the presence of hydrocarbons. Zeolite shells not only plaid a key role as membranes, thus changing selectivities as compared to conventional supported catalysts, but they also protected metal nanoparticles from sintering under reaction conditions
6
Haridas, M. "Role Of Surface And Inter-particle Spacing On Optical Properties Of Single And Hybrid Nanoparticle Assemblies." Thesis, 2011. http://hdl.handle.net/2005/2101.
Full textAbstract:
Optical properties of nanoscopic materials have been intensively perused over last couple of decades due to their tunable optical properties. Recent interests in this field have been mainly focused on the preparation of ordered arrays of nanoscopic materials and study of their optical properties. These interests have been motivated by the usability of such systems for nano photonic devices. Theoretical predictions from such systems reveal complex absorption and emission properties, different from individual ones mainly because of energy transfer between them. These properties can be controlled further by preparing hybrid arrays of nanostructures, including nano crystals of different types. Hybrid arrays with semiconducting quantum dots and metallic nanoparticles are an example of such system. Optical properties of such a system can be tuned by controlling the interaction between excitons and plasmons. This the-sis presents the experimental studies on optical properties of polymer capped polymer nanoparticles, quantum dot arrays and hybrid arrays with semiconducting quantum dot and metal nanoparticles. A brief summary of the experi-mental methods and results have been highlighted below.
First chapter deals with the theoretical aspects of confined nanoscopic materials, especially describing the physics of zero dimensional systems and its optical properties. The discussions are mostly focused on two types of nano materials cadmium selenide (CdSe) quantum dot (QDs) and gold nano particles (Au NPs), used for the experimental study. Variation of energy levels of CdSe QDs and its absorption and emission properties under strong confinement regime has been discussed with respect to effective mass approximation (EMA) model. This is followed by the discussion on optical properties of Au NPs, describing absorption properties, based on Mie theory. Size dependent variation of absorption spectra of Au NPs and the modifications based on different models has been discussed. Second part of the chapter describes the physics of QD arrays and theory of exciton plasmon interactions based on the recent literatures. Energy transfer mechanism between semiconducting QDs and metal nanoparticles has been discussed based on numerical method and dipole approximation. Second chapter deals with the discussion on experimental techniques used for the study. Chapter 2 starts with the discussion on the synthesis method for CdSe QDs and Au NPs with different capping ligands. Preparation of QD ar-rays and hybrid arrays using self assembly technique has been discussed in this chapter. Preparation CdSe QD arrays and hybrid arrays with CdSe QDs and Au NPs using block copolymer (BCP) template and Langmuir Blodgett (LB) technique has been the main focus in the discussion. This is followed by the discussion on optical microscopy techniques, confocal, near field scanning microscopy (NSOM), Brewster angle microscopy and electron microscopy techniques, transmission electron microscopy and scanning electron microscopy.
Studies on variation of band structure of small polymer capped Au NPs, with respect to the size and grafting density of the capping polymer is discussed in chapter 3. Polymer capped Au NPs with sizes 2-5 nm was used for the study. Dielectric constants of Au NPs were extracted from the absorption spectra by fitting the data using modified Mie theory. Dielectric constants of Au NPs were reproduced using an analytical expression, describing the contribution from different transitions in the optical regions. Results indicate systematic variations of the band structure with respect to the particle size and grafting density. The observations have been interpreted in terms of variation of co ordination number and chemical interaction of capping polymer with the surface atoms. Our new method analysis points to the importance of both quantum and surface effects in determining optical and electronic properties of polymer capped gold nanoparticles. Chapter 4 describes the study on morphology of the CdSe QD arrays prepared using different BCP templates and its correlation with optical properties. Spatially resolved spectra from the thin films of QD arrays were collected in near field and the compared with the spectra collected in far field. Spectra collected in near field mode shows sharp features in the emission spectra, possibly indicating the interaction of optical near field with QD excitation. It has been suggested that such fine structure could be induced by coupling between optical near filed and excitons and this coupling seems to be determined by local heterogeneity in QD density and disorder. Variation of exciton life time with respect to QD density and absorption spectra from the QD -BCP system is also described in chapter 4.
Chapter 5 and 6 deals with the experimental studies on exciton -plasmon interaction in hybrid arrays of CdSe QDs and Au NPs. Emission properties hybrid arrays prepared using BCP templates has been the focus of chapter 5. Photoluminescence (PL) and lifetime measurements were performed on hybrid arrays and their variation with respect to the density and dispersion of Au NPs has been described. Optical measurements were performed on two sets of films using two different sizes of CdSe QDs, with the smaller QD emission overlapping with the plasmon resonance of Au NPs, while a red shifted emission peak for larger QDs. PL emission from hybrid arrays with smaller QDs shows en-hancement/quenching with respect to the dispersion of Au NPs, also showing systematic reduction of life time of CdSe QDs with Au NP density. Even though enhancement/quenching of emission properties of hybrid film with large QD shows similar behavior, PL decay measurements from such films shows non monotonic variation of exciton life time with respect to Au NP density. The enhancement/quenching behavior of the PL emission has been explained in terms of two competing mechanism, electromagnetic field enhancement and non radiative energy transfer. However to explain the energy transfer mechanism in hybrid arrays requires more systematic calculations.
Chapter 6 describes the optical properties of highly compact hybrid arrays prepared using LB techniques. Hybrid arrays prepared at the air water inter-face were transferred to a glass substrates. The main focus on chapter 6 is to study the emission properties of highly compact hybrid arrays with respect to the spectral overlap between exciton energy of CdSe QDs and plasmon band of Au NPs with respect to their surface density (inter particle distance). Hybrid arrays were prepared with three types of QDs, with smaller QDs emission peak overlapping with plasmon band of Au NPs and clearly separated exciton and plasmon band for largest QDs. The PL emission from hybrid arrays with smaller QDs shows quenching, compared to strong enhancement in the emission from hybrid films with larger QDs. The disagreement of the observed results with respect to the theoretical calculations based on dipole approximation has been highlighted in the chapter. Chapter 7 includes the summary of the experimental results and the future works to be carried out as a continuation of the work presented in this thesis.
7
Yao, Cheng-Thai, and 姚承泰. "Single Gyroid-Nanostructured Metals with Controlled Particle Size from Electroless Plating Using Double Gyroid-Forming Block Copolymer Template." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/49383830310915419463.
Full textAbstract:
碩士國立清華大學
化學工程學系
104
In this study, by taking advantage of the nucleation and growth control of templated electroless plating, a novel approach to fabricate metallic materials with single gyroid (SG) texture using polymer template with double gyroid (DG) texture is suggested. Nanoporous polystyrene (PS) with DG texture is prepared from the self-assembly of polystyrene-b-poly(L-lactide) (PS-PLLA) followed by hydrolysis of PLLA block, and then used as a template for templated electroless plating. With pore-filling of the dilute Pd solution to the PS template, homogeneously distributed Pd clusters within the PS template can be prepared by using hydrazine for the reduction of Pd ions, giving one single Pd nuclei for the growth of SG-structured Ni. Subsequently, the Ni deposition using the Pd nuclei as catalytic site can be carried out to form SG-structured Ni. Finally, nanoporous Ni with SG-structured texture can be obtained after removal of the PS template by washing with dichloromethane. With the novel approach, SG-structured Ni with controlled particle radius from hundreds nm to micrometer can be prepared by tuning the growth time for the Ni deposition. Furthermore, tunable lattice constant of the SG-structured Ni and the corresponding filling ratio of the nanoporous Ni can be created from the pre-synthesized PS template with different molecular weights and compositions. To effectively achieve versatile purposes for optical applications, SG-structured Au is synthesized via the novel method as described above. As a result, this approach develop a platform technology to fabricate SG-structured metallic nanomaterials with versatile characteristic for novel properties from the nucleation and growth of templated electroless plating using self-assembled DG-structured block copolymers (BCPs) as templates.
8
Castelino, Ajay. "The effect of single sessions of music therapy on the level of anxiety in older persons with psychiatric disorders : a pilot study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Music Therapy at the New Zealand School of Music, Wellington, New Zealand." 2009. http://hdl.handle.net/10179/1207.
Full textAbstract:
This pilot study examined the effects of single sessions of music therapy on the level of anxiety in older persons with psychiatric disorders. The studied intervention was a 30 minute music therapy group and the control intervention was a verbal therapeutic intervention in the form of a reminiscence group. Participants acted as their own control. The measurement tool was the state part of a “State Trait Anxiety Inventory”. It was administered a total of four times, pre- and post- the music therapy intervention and preand post- the reminiscence therapy (control) group. A total of 9 participants were recruited for the study. The results indicated that single sessions of music therapy significantly reduced the level of anxiety for older persons with psychiatric disorders [t(8)=4.626, p<0.0017] as compared to the control intervention as measured by the state part of the “State Trait Anxiety Inventory”. There was no evidence for a significant carryover effect since the baselines prior to each intervention did not differ significantly (p=0.55). These results can be considered to be a part of a pilot study and early inquiry into this field since methodological difficulties and the time limitation of the research resulted in some necessary deviations from the original protocol. A major limitation of the study was the choice of a measurement tool, which required the client to be cognitively high functioning. Thus these results are limited to cognitively able clients, which is a relatively small proportion of this client group that could potentially benefit from music therapy. It is suggested that for future research with this client group the measured variable be physical relaxation, rather than anxiety.
Books on the topic "Single metal particle"
1
Stainton, Robert J. Meaning and Reference: Some Chomskian Themes. Edited by Ernest Lepore and Barry C. Smith. Oxford University Press, 2009. http://dx.doi.org/10.1093/oxfordhb/9780199552238.003.0036.
Full textAbstract:
This article introduces three arguments that share a single conclusion: that a comprehensive science of language cannot (and should not try to) describe relations of semantic reference, i.e. word–world relations. Spelling this out, if there is to be a genuine science of linguistic meaning (yielding theoretical insight into underlying realities, aiming for integration with other natural sciences), then a theory of meaning cannot involve assigning external, real-world, objects to names, nor sets of external objects to predicates, nor truth values (or world-bound thoughts) to sentences. Most of the article tries to explain and defend this broad conclusion. The article also presents, in a very limited way, a positive alternative to external-referent semantics for expressions. This alternative has two parts: first, that the meanings of words and sentences are mental instructions, not external things; second, that it is people who refer (and who express thoughts) by using words and sentences, and word/sentence meanings play but a partial role in allowing speakers to talk about the world.
2
Pollock, Rob. Total hip replacement: modes of failure. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199550647.003.007010.
Full textAbstract:
♦ Total hip replacements (THRs) may fail in various ways. They may become infected, they may be subject to aseptic loosening, they may dislocate, or a periprosthetic fracture may occur. The patient with a failed THR must be thoroughly assessed before treatment is contemplated♦ Infection may be acute or chronic. Assessment involves clinical assessment, plain radiographs, blood tests (C-reactive protein and erythrocyte sedimentation rate), hip aspiration, and, sometimes, nuclear medicine. The acutely infected hip may be treated with one-stage revision. This involves thorough lavage, debridement, and exchange of all modular components as well as long-term antibiotic therapy. The gold standard of treatment for a chronically infected THR is a two-stage revision. Success rates of 80–90% can be expected♦ Aseptic loosening typically occurs at the cement bone interface in hips where a metal-on-polyethylene bearing couple has been used. Bone resorption takes place as a result of an inflammatory response to small wear particles. After infection has been excluded the treatment of choice is a single-stage revision♦ Dislocation may be the result of patient factors, implant factors, or poor surgical technique. It is imperative for the clinician to minimize the risk by selecting patients carefully, using the correct combination of implants and performing surgery accurately♦ The management of periprosthetic fractures depends on how well the implants are fixed and quality of bone stock. Treatment ranges from simple fixation of the fracture through to revision augmented with strut allograft.
3
Frew, Anthony. Air pollution. Edited by Patrick Davey and David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0341.
Full textAbstract:
Any public debate about air pollution starts with the premise that air pollution cannot be good for you, so we should have less of it. However, it is much more difficult to determine how much is dangerous, and even more difficult to decide how much we are willing to pay for improvements in measured air pollution. Recent UK estimates suggest that fine particulate pollution causes about 6500 deaths per year, although it is not clear how many years of life are lost as a result. Some deaths may just be brought forward by a few days or weeks, while others may be truly premature. Globally, household pollution from cooking fuels may cause up to two million premature deaths per year in the developing world. The hazards of black smoke air pollution have been known since antiquity. The first descriptions of deaths caused by air pollution are those recorded after the eruption of Vesuvius in ad 79. In modern times, the infamous smogs of the early twentieth century in Belgium and London were clearly shown to trigger deaths in people with chronic bronchitis and heart disease. In mechanistic terms, black smoke and sulphur dioxide generated from industrial processes and domestic coal burning cause airway inflammation, exacerbation of chronic bronchitis, and consequent heart failure. Epidemiological analysis has confirmed that the deaths included both those who were likely to have died soon anyway and those who might well have survived for months or years if the pollution event had not occurred. Clean air legislation has dramatically reduced the levels of these traditional pollutants in the West, although these pollutants are still important in China, and smoke from solid cooking fuel continues to take a heavy toll amongst women in less developed parts of the world. New forms of air pollution have emerged, principally due to the increase in motor vehicle traffic since the 1950s. The combination of fine particulates and ground-level ozone causes ‘summer smogs’ which intensify over cities during summer periods of high barometric pressure. In Los Angeles and Mexico City, ozone concentrations commonly reach levels which are associated with adverse respiratory effects in normal and asthmatic subjects. Ozone directly affects the airways, causing reduced inspiratory capacity. This effect is more marked in patients with asthma and is clinically important, since epidemiological studies have found linear associations between ozone concentrations and admission rates for asthma and related respiratory diseases. Ozone induces an acute neutrophilic inflammatory response in both human and animal airways, together with release of chemokines (e.g. interleukin 8 and growth-related oncogene-alpha). Nitrogen oxides have less direct effect on human airways, but they increase the response to allergen challenge in patients with atopic asthma. Nitrogen oxide exposure also increases the risk of becoming ill after exposure to influenza. Alveolar macrophages are less able to inactivate influenza viruses and this leads to an increased probability of infection after experimental exposure to influenza. In the last two decades, major concerns have been raised about the effects of fine particulates. An association between fine particulate levels and cardiovascular and respiratory mortality and morbidity was first reported in 1993 and has since been confirmed in several other countries. Globally, about 90% of airborne particles are formed naturally, from sea spray, dust storms, volcanoes, and burning grass and forests. Human activity accounts for about 10% of aerosols (in terms of mass). This comes from transport, power stations, and various industrial processes. Diesel exhaust is the principal source of fine particulate pollution in Europe, while sea spray is the principal source in California, and agricultural activity is a major contributor in inland areas of the US. Dust storms are important sources in the Sahara, the Middle East, and parts of China. The mechanism of adverse health effects remains unclear but, unlike the case for ozone and nitrogen oxides, there is no safe threshold for the health effects of particulates. Since the 1990s, tax measures aimed at reducing greenhouse gas emissions have led to a rapid rise in the proportion of new cars with diesel engines. In the UK, this rose from 4% in 1990 to one-third of new cars in 2004 while, in France, over half of new vehicles have diesel engines. Diesel exhaust particles may increase the risk of sensitization to airborne allergens and cause airways inflammation both in vitro and in vivo. Extensive epidemiological work has confirmed that there is an association between increased exposure to environmental fine particulates and death from cardiovascular causes. Various mechanisms have been proposed: cardiac rhythm disturbance seems the most likely at present. It has also been proposed that high numbers of ultrafine particles may cause alveolar inflammation which then exacerbates preexisting cardiac and pulmonary disease. In support of this hypothesis, the metal content of ultrafine particles induces oxidative stress when alveolar macrophages are exposed to particles in vitro. While this is a plausible mechanism, in epidemiological studies it is difficult to separate the effects of ultrafine particles from those of other traffic-related pollutants.
4
Papanicolopulu, Irini. People, the Sea, and International Law. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789390.003.0002.
Full textAbstract:
The chapter presents the factual and legal background to the discussion of people at sea. Firstly, it provides some background discussion concerning the presence of people at sea and the risks these people face. Secondly, it briefly presents the legal rules that have been adopted specifically to protect some of the categories of people who are at sea and concludes that they provide only a partial and uneven protection. Current efforts to address the specific challenges faced by people at sea are not effective, since legal analysis is based upon the identification of a discrete field, often in conjunction with a specific forum, within which the particular problem is addressed. This approach results in piece-meal solutions that do not devote sufficient attention to the human nature of all people who are at sea, resulting in different levels of protection and, sometimes, an unjustified difference in treatment.
Book chapters on the topic "Single metal particle"
1
Averin, D. V., and A. N. Korotkov. "Correlated Single-Electron Tunneling via Ultrasmall Metal Particle." In Topics in Molecular Organization and Engineering, 9–15. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3392-0_2.
Full text
2
Lee, Donggeun, Art Miller, David Kittelson, and Michael R. Zachariah. "Single-Particle Mass Spectrometry of Metal-Bearing Diesel Nanoparticles." In Nanotechnology and the Environment, 142–51. Washington, DC: American Chemical Society, 2004. http://dx.doi.org/10.1021/bk-2005-0890.ch017.
Full text
3
Schönenberger, C. "Single-electron tunneling through an ultra-small metal particle." In Computations for the Nano-Scale, 257–69. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1956-6_21.
Full text
4
Brom, H. B., J. J. van der Klink, F. C. Fritschij, L. J. de Jongh, R. Della Pergola, and A. Ceriotti. "NMR in powders and single crystals of the metal-alloy cluster [HNi38Pt6(CO)48]5–." In Small Particles and Inorganic Clusters, 559–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-60854-4_134.
Full text
5
Saito, Yahachi, Tadao Koyama, and Kenichiro Kawabata. "Growth of single-layer carbon tubes assisted with iron-group metal catalysts in carbon arc." In Small Particles and Inorganic Clusters, 421–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-60854-4_99.
Full text
6
Zolnikov, Konstantin P., Dmitrij S. Kryzhevich, and Aleksandr V. Korchuganov. "Regularities of Structural Rearrangements in Single- and Bicrystals Near the Contact Zone." In Springer Tracts in Mechanical Engineering, 301–22. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60124-9_14.
Full textAbstract:
AbstractThe chapter is devoted to the analysis of the features of local structural rearrangementsin nanostructured materialsunder shear loadingand nanoindentation. The study was carried out using molecular dynamics-based computer simulation. In particular, we investigated the features of symmetric tilt grain boundary migration in bcc and fcc metals under shear loading. The main emphasis was on identifying atomic mechanisms responsible for the migration of symmetric tilt grain boundaries. We revealed that grain boundaries of this type can move with abnormally high velocities up to several hundred meters per second. The grain boundary velocity depends on the shear rate and grain boundary structure. It is important to note that the migration of grain boundary does not lead to the formation of structural defects. We showed that grain boundary moves in a pronounced jump-like manner as a result of a certain sequence of self-consistent displacements of grain boundary atomic planes and adjacent planes. The number of atomic planes involved in the migration process depends on the structure of the grain boundary. In the case of bcc vanadium, five planes participate in the migration of the Σ5(210)[001] grain boundary, and three planes determine the Σ5(310)[001] grain boundary motion. The Σ5(310)[001] grain boundary in fcc nickel moves as a result of rearrangements of six atomic planes. The stacking order of atomic planes participating in the grain boundary migration can change. A jump-like manner of grain boundary motion may be divided into two stages. The first stage is a long time interval of stress increase during shear loading. The grain boundary is motionless during this period and accumulates elastic strain energy. This is followed by the stage of jump-like grain boundary motion, which results in rapid stress drop. The related study was focused on understanding the atomic rearrangements responsible for the nucleation of plasticity near different crystallographic surfaces of fcc and bcc metals under nanoindentation. We showed that a wedge-shaped region, which consists of atoms with a changed symmetry of the nearest environment, is formed under the indentation of the (001) surface of the copper crystallite. Stacking faults arise in the (111) atomic planes of the contact zone under the indentation of the (011) surface. Their escape on the side free surface leads to a step formation. Indentation of the (111) surface is accompanied by nucleation of partial dislocations in the contact zone subsequent formation of nanotwins. The results of the nanoindentation of bcc iron bicrystal show that the grain boundary prevents the propagation of structural defects nucleated in the contact zone into the neighboring grain.
7
Springborg, M., and Y. Dong. "Chapter 2 Single-Particle Properties." In Handbook of Metal Physics, 3–20. Elsevier, 2006. http://dx.doi.org/10.1016/s1570-002x(06)01002-0.
Full text
8
Gundlach-Graham, Alexander. "Multiplexed and multi-metal single-particle characterization with ICP-TOFMS." In Analysis and Characterisation of Metal-Based Nanomaterials, 69–101. Elsevier, 2021. http://dx.doi.org/10.1016/bs.coac.2021.01.008.
Full text
9
Laborda, Francisco, Ana C. Gimenez-Ingalaturre, and Eduardo Bolea. "Single-particle inductively coupled plasma mass spectrometry for the analysis of inorganic engineered nanoparticles: Metrological and quality issues." In Analysis and Characterisation of Metal-Based Nanomaterials, 35–67. Elsevier, 2021. http://dx.doi.org/10.1016/bs.coac.2021.02.012.
Full text
10
Vidmar, Janja. "Detection and characterization of metal-based nanoparticles in environmental, biological and food samples by single particle inductively coupled plasma mass spectrometry." In Analysis and Characterisation of Metal-Based Nanomaterials, 345–80. Elsevier, 2021. http://dx.doi.org/10.1016/bs.coac.2021.02.008.
Full textConference papers on the topic "Single metal particle"
1
Festag, Grit, Thomas Schüler, Andrea Steinbrück, Andrea Csáki, and Wolfgang Fritzsche. "Specific Metal Deposition onto Immobilized Metal Nanoparticles Studied on Single Particle Level." In DNA-BASED NANOSCALE INTEGRATION: International Symposium on DNA-Based Nanoscale Integration. AIP, 2006. http://dx.doi.org/10.1063/1.2360587.
Full text
2
Del Fatti, Natalia, Otto Muskens, Dimitris Christofilos, and Fabrice Vallee. "Optical spectroscopy of metal nanoparticles: single particle detection (Invited Paper)." In Integrated Optoelectronic Devices 2005, edited by Kong-Thon Tsen, Jin-Joo Song, and Hongxing Jiang. SPIE, 2005. http://dx.doi.org/10.1117/12.592774.
Full text
3
Xiao, Bin, and Yuwen Zhang. "Partial Melting and Resolidification of Single-Component Metal Powder With a Moving Laser Beam." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72161.
Full textAbstract:
Partial melting and resolidification of single-component metal powders with a moving laser beam is investigated numerically. Since laser processing of metal powder is a very rapid process, the liquid layer and solid core of a partially molten powder particle may not at thermal equilibrium and have different temperatures: the temperature of the liquid part is higher than the melting point, and the temperature of the solid core is below the melting point. Therefore, the local temperature of regions with partial molten particles is within a range of temperature adjacent to the melting point, instead of at the melting point. The partial melting of the metal powder is also accompanied by shrinkage that drives out the gas in the powder bed and the powder structure is supported by the solid core of the partially melted powder particles. Melting with shrinkage and resolidification are described using a temperature transforming model. The convection driven by capillary and gravity forces in the melting liquid pool is formulated by using Darcy’s law. The effects of laser beam intensity and scanning velocity on the shape and size of the heat affected zone and molten pool are investigated.
4
Murakami, Ayako, Tatsushi Matsuyama, Junichi Ida, and Hideo Yamamoto. "Measurement of Accumulation Process of Electrostatic Charge on Single Particle Due to Cascade Impacts onto Metal Wall." In 5th Asian Particle Technology Symposium. Singapore: Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-2518-1_187.
Full text
5
Scherer, Norbert F., Matthew Pelton, Rongchao Jin, Justin E. Jureller, Mingzhao Liu, Hee Y. Kim, Sungnam Park, and Philippe Guyot-Sionnest. "Optical nonlinearities of metal nanoparticles: single-particle measurements and correlation to structure." In SPIE Optics + Photonics, edited by Mark I. Stockman. SPIE, 2006. http://dx.doi.org/10.1117/12.680151.
Full text
6
Austin, Morgan, Thao Tran-Le, Robert Kunz, Timothy Simpson, and Rui Ni. "Experimental and Computational Studies of Particle Scavenge Flow in Direct Laser Metal Sintering." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4965.
Full textAbstract:
Abstract Powder Bed Fusion (PBF) cross-flow systems are designed to flow gas across the build plane and entrain metallic powder particles that are ejected during the build, due to the thermal and attendant released kinetic energy of the laser melt process. It is important that these particles be removed from the build chamber so that they do not redeposit on the build surface, as this uncontrolled particle deposition can degrade the part quality. Optimal design of these sub-systems involves tailoring a cross-flow jet such that most of the ejected particles are entrained and removed from the build chamber, while the top layer of particles that are freshly spread on the build plate are not entrained. Accordingly, a combined experimental and CFD study has been executed with the goal of developing engineering design guidance for these cross-flow systems. The closed loop small footprint wind tunnel incorporates a 0.305 m × 0.305 m × 0.915 m test section, a variable height build plate upon which powder can be spread, a variable geometry inlet nozzle, and variable flow rate so that a variety of cross-flow configurations can be tested. Helium bubble particle tracking velocimetry (PTV) was used to characterize the single-phase flow at a number of these operating conditions / configurations. In addition, high speed videography was used to study particle liftoff and entrainment at these same conditions. Using these measurements and attendant CFD models, critical particle liftoff Shield numbers were obtained using CFD predictions of friction velocity. Specifically, close agreement between CFD and measurements were obtained, so that predicted Shields numbers, Sh, could be correlated with particle Reynolds number, Reτ. In this paper we present details of the experimental facility and test program, experimental results including uncertainty/error analysis for the PTV measurements, as well as the videography results for an aluminum alloy powder. The results of the CFD modeling are compared to the single phase measurements. Since very good agreement is observed, predicted wall-shear stress values are used to estimate Sh vs. Reτ at flow rates where incipient particle lift-off is observed experimentally.
7
Scherer, Norbert F., Matthew Pelton, Rongchao Jin, Justin E. Jureller, Mingzhao Liu, Hee Y. Kim, Sungnam Park, and Philippe Guyot-Sionnest. "Ultrafast Optical Nonlinearities of Metal Nanoparticles: Single-Particle Measurements and Correlation to Structure." In International Conference on Ultrafast Phenomena. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/up.2006.tud4.
Full text
8
Che-Hao Shih, Kai-Chi Chen, and Hsun-Tien Li. "Mechanical and electrical properties investigation of micro-size single metal-coated polymer particle." In 2015 International Conference on Electronic Packaging and iMAPS All Asia Conference (ICEP-IAAC). IEEE, 2015. http://dx.doi.org/10.1109/icep-iaac.2015.7111071.
Full text
9
Xiao, Bin, and Yuwen Zhang. "Analysis of Melting in a Single-Component Metal Powder Bed Subject to Constant Heat Flux Heating." In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56362.
Full textAbstract:
To model Selective Laser Sintering (SLS) of single-component metal powders, melting of a subcooled powder bed with single-component metal powder is investigated analytically. Since laser processing of metal powder is a very rapid process, the liquid and solid phases of a partially molten powder particle may have different temperatures: the temperature in the liquid phase is higher than the melting point, and the temperature in the solid phase is below the melting point. Therefore, the local temperature of regions with partial molten particles is within a range of temperature adjacent to the melting point, instead of at melting point. In addition, the powder bed experiences a significant density change during melting. Therefore, melting of a metal powder bed can be modeled as a melting that occurs in a range of temperature with significant density change. The temperature distributions and locations of the various interfaces were obtained by solving the governing equations for solid, liquid and mushy zones in a one-dimensional system using an integral approximate method. The effects of porosity, sub-cooling, dimensionless thermal conductivity of gas, and dimensionless heat flux on the surface temperature and locations of the interfaces were investigated.
10
Yildirim, Baran, Sinan Mu¨ftu¨, and Andrew Gouldstone. "On Cohesion of Micron Scale Metal Particles in High Velocity Impact With a Metal Substrate." In ASME/STLE 2011 International Joint Tribology Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ijtc2011-61084.
Full textAbstract:
Impact of a single copper particle in cold gas dynamic spray is simulated by finite element method by including the effects of high strain rates and temperature on material plasticity and failure. In order to predict stick behavior of the particle, cohesive forces that act between the particle and the substrate are included in the model by defining an interfacial cohesive strength parameter. Effect of this parameter on the deformation and stick/rebound behavior of the particle is studied. It is found that significant particle deformation, large area of contact between particle and substrate is needed to generate enough cohesive force to absorb the rebound energy of the particle and achieve sticking. As the impact velocity and assumed interfacial cohesive strength increases, particle is more likely to stick on to the substrate. Critical velocities in the same range with experimental results are predicted.
Reports on the topic "Single metal particle"
1
Saldanha, Ian J., Wangnan Cao, Justin M. Broyles, Gaelen P. Adam, Monika Reddy Bhuma, Shivani Mehta, Laura S. Dominici, Andrea L. Pusic, and Ethan M. Balk. Breast Reconstruction After Mastectomy: A Systematic Review and Meta-Analysis. Agency for Healthcare Research and Quality (AHRQ), July 2021. http://dx.doi.org/10.23970/ahrqepccer245.
Full textAbstract:
Objectives. This systematic review evaluates breast reconstruction options for women after mastectomy for breast cancer (or breast cancer prophylaxis). We addressed six Key Questions (KQs): (1) implant-based reconstruction (IBR) versus autologous reconstruction (AR), (2) timing of IBR and AR in relation to chemotherapy and radiation therapy, (3) comparisons of implant materials, (4) comparisons of anatomic planes for IBR, (5) use versus nonuse of human acellular dermal matrices (ADMs) during IBR, and (6) comparisons of AR flap types. Data sources and review methods. We searched Medline®, Embase®, Cochrane CENTRAL, CINAHL®, and ClinicalTrials.gov from inception to March 23, 2021, to identify comparative and single group studies. We extracted study data into the Systematic Review Data Repository Plus (SRDR+). We assessed the risk of bias and evaluated the strength of evidence (SoE) using standard methods. The protocol was registered in PROSPERO (registration number CRD42020193183). Results. We found 8 randomized controlled trials, 83 nonrandomized comparative studies, and 69 single group studies. Risk of bias was moderate to high for most studies. KQ1: Compared with IBR, AR is probably associated with clinically better patient satisfaction with breasts and sexual well-being but comparable general quality of life and psychosocial well-being (moderate SoE, all outcomes). AR probably poses a greater risk of deep vein thrombosis or pulmonary embolism (moderate SoE), but IBR probably poses a greater risk of reconstructive failure in the long term (1.5 to 4 years) (moderate SoE) and may pose a greater risk of breast seroma (low SoE). KQ 2: Conducting IBR either before or after radiation therapy may result in comparable physical well-being, psychosocial well-being, sexual well-being, and patient satisfaction with breasts (all low SoE), and probably results in comparable risks of implant failure/loss or need for explant surgery (moderate SoE). We found no evidence addressing timing of IBR or AR in relation to chemotherapy or timing of AR in relation to radiation therapy. KQ 3: Silicone and saline implants may result in clinically comparable patient satisfaction with breasts (low SoE). There is insufficient evidence regarding double lumen implants. KQ 4: Whether the implant is placed in the prepectoral or total submuscular plane may not be associated with risk of infections that are not explicitly implant related (low SoE). There is insufficient evidence addressing the comparisons between prepectoral and partial submuscular and between partial and total submuscular planes. KQ 5: The evidence is inconsistent regarding whether human ADM use during IBR impacts physical well-being, psychosocial well-being, or satisfaction with breasts. However, ADM use probably increases the risk of implant failure/loss or need for explant surgery (moderate SoE) and may increase the risk of infections not explicitly implant related (low SoE). Whether or not ADM is used probably is associated with comparable risks of seroma and unplanned repeat surgeries for revision (moderate SoE for both), and possibly necrosis (low SoE). KQ 6: AR with either transverse rectus abdominis (TRAM) or deep inferior epigastric perforator (DIEP) flaps may result in comparable patient satisfaction with breasts (low SoE), but TRAM flaps probably increase the risk of harms to the area of flap harvest (moderate SoE). AR with either DIEP or latissimus dorsi flaps may result in comparable patient satisfaction with breasts (low SoE), but there is insufficient evidence regarding thromboembolic events and no evidence regarding other surgical complications. Conclusion. Evidence regarding surgical breast reconstruction options is largely insufficient or of only low or moderate SoE. New high-quality research is needed, especially for timing of IBR and AR in relation to chemotherapy and radiation therapy, for comparisons of implant materials, and for comparisons of anatomic planes of implant placement.