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Articles de revues sur le sujet "Metal Nano-particles"
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Xu, Luping, Zhongqin Guo, Hanyu Jiang, Siyu Xu, Juanli Ma, Mi Hu, Jiemei Yu, Fengqi Zhao et Taizhong Huang. « Dimethylglyoxime Clathrate as Ligand Derived Nitrogen-Doped Carbon-Supported Nano-Metal Particles as Catalysts for Oxygen Reduction Reaction ». Nanomaterials 11, no 5 (18 mai 2021) : 1329. http://dx.doi.org/10.3390/nano11051329.
Texte intégralRésumé :
Nitrogen-doped carbon-supported metal nano-particles show great promise as high-performance catalysts for novel energies, organic synthesis, environmental protection, and other fields. The synergistic effect between nitrogen-doped carbon and metal nano-particles enhances the catalytic properties. Thus, how to effectively combine nitrogen-doped carbon with metal nano-particles is a crucial factor for the synthesis of novel catalysts. In this paper, we report on a facile method to prepare nitrogen-doped carbon-supported metal nano-particles by using dimethylgly-oxime as ligand. The nano-particles of Pd, Ni, Cu, and Fe were successfully prepared by the pyrolysis of the corresponding clathrate of ions and dimethylglyoxime. The ligand of dimethylglyoxime is adopted as the source for the nitrogen-doped carbon. The nano-structure of the prepared Pd, Ni, Cu, and Fe particles are confirmed by X-ray diffraction, scanning electron microscopy, and trans-mission electron microscopy tests. The catalytic performances of the obtained metal nano-particles for oxygen reduction reaction (ORR) are investigated by cyclic voltammetry, Tafel, linear sweeping voltammetry, rotating disc electrode, rotating ring disc electrode, and other technologies. Results show that the nitrogen-doped carbon-supported metal nano-particles can be highly efficient catalysts for ORR. The results of the paper exhibit a facile methodology to prepare nitrogen-doped carbon-supported metal nano-particles.
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Li, Nan, Mingchang Wang et Zhiguo Wu. « Mass-Produced Cu Nanoparticles as Lubricant Additives to Enhance the Tribological Properties of DLC Coatings ». Metals 12, no 8 (13 août 2022) : 1350. http://dx.doi.org/10.3390/met12081350.
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In this paper, Nano copper (Cu) particles with a core-shell structure and good spherical shape were prepared by an innovative method called mass-produced nanoparticles (MPNP). The prepared Cu nanoparticles have good dispersibility and are agglomeration-free in Pao oil. In particular, the effects of nano-Cu particles with different mass fractions on the tribological properties of the steel against diamond-like carbon (DLC) coating were studied systematically. The results showed that the nano-Cu particles with the mass fraction of 0.1 wt.% and the steel/DLC friction pairs had good synergistic lubrication. The friction mechanism of the metal nano-particles and carbon-based coatings mainly depends on the physical effects such as nano-bearing and nano-filling of the nano-particles, which has little correlation with the shear film formation of the metal nano-particles. Therein, the surface polish behaviors of the metal nano-particles and carbon-based coatings are the key to bringing the nano-bearing mechanism of nano-particles into full play. Therefore, the Cu nanoparticles prepared by MPNP show excellent tribological performance and possess broad prospects in the fields of lubricant additives.
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Hayashi, Yamato, Hirotsugu Takizawa, Yoshitaka Saijo, Tohru Sekino, Katsuaki Suganuma et Koichi Niihara. « Fabrication and Applications of Nano-Metal Particle Composites by Ultrasonic Eco-Process ». Key Engineering Materials 317-318 (août 2006) : 231–34. http://dx.doi.org/10.4028/www.scientific.net/kem.317-318.231.
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Nano-sized metal particles have recently attracted considerable interest owing to their application potential. Such particles can be synthesized using physical and chemical methods. In this study, nano-sized noble metals were synthesized through the reaction of metal oxides by ultrasonic. This means that the chemical reactions which take place under conventional conditions can be accelerated by ultrasonic cavitations. In general, the chemical effects of ultrasonic irradiation fall into three areas: homogeneous sonochemical efffects of liquids, heterogeneous sonochemical effects of liquid-liquid or liquid-solid systems, and sonocatalytic effects. It has been proposed that liquid-liquid systems are used for the fabrication of nano-metal particles in the past. In this study, the fabrication of nano-metal particles and supported composites was investigated for the liquid-solid system from a viewpoint of economy and ecology. By choosing suitable conditions, it is reasonable to expect that these simple ultrasonic processes can be extended to obtain nano-sized metal particles. Thus applications by using these reactions were investigated to prepare the nano-sized metal particle supported materials, and mechanisms were investigated.
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Kračun, Ana, Fevzi Kafexhiu, Franc Tehovnik et Bojan Podgornik. « Effective Casting Technique of Nano-Particles Alloyed Austenitic Stainless Steel ». Metals 10, no 10 (25 septembre 2020) : 1287. http://dx.doi.org/10.3390/met10101287.
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In recent decades, considerable efforts have been made in the production of steel and the modification of its microstructure on the nano-scale in order to improve its mechanical properties. One possibility is through nano-particles incorporation and reinforcement. While typical production methods for Metal Matrix nano-Composites (MMnCs) are difficult and expensive, the main drawback of the casting method is the agglomeration of the nano-particles and a poor interface between the nano-particles and the metal matrix. Therefore, the aim of this study was to investigate the potential of adding nano-particles as reinforcement elements through the conventional liquid-metal casting process. The investigation was focused on the various approaches to the modification and addition of nano-particles in the melt, as well as the influence of particle concentration and size on their homogeneity and distribution within the steel matrix. The results show that also in the case of the conventional casting process, it is possible to produce a reinforced steel-matrix nano-composite with a homogeneous distribution of the Al2O3 nano-particles in the matrix. However, in order to obtain a homogeneous distribution of nano-particles in the steel matrix, a dispersion agent is required.
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Hansen, Dane, Jon Kellar et William Cross. « Nanotechnology and Silver-Metal Clay for Artisans ». Leonardo 44, no 2 (avril 2011) : 166–67. http://dx.doi.org/10.1162/leon_a_00124.
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Nano-scale silver particles are utilized in the production of a metal clay, which upon firing is reduced to a solid metal article. The metal clay, because of the nano-scale particles, can be fired in a conventional home oven.
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Rahman, Abdul, Amri Ismail, Desi Jumbianti, Stella Magdalena et Hanggara Sudrajat. « SYNTHESIS OF COPPER OXIDE NANO PARTICLES BY USING Phormidium cyanobacterium ». Indonesian Journal of Chemistry 9, no 3 (24 juin 2010) : 355–60. http://dx.doi.org/10.22146/ijc.21498.
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In this paper, we report a suitable method for extracellular synthesis of copper oxide nano particles by using Phormidium cyanobacterium. We hypothesize that synthesis of copper oxide nano particles is believed to occur by extracellular hydrolysis of the cationic copper by certain metal chelating anionic proteins/reductase secreted by bacteria under simple experimental conditions like aerobic environment, neutral pH and room temperature. Proteins not only reduce Cu (II) into copper oxide nano particles (CONPs) but also plays significant role in stabilization of formed nanoparticles at room temperature. Further TEM, SEM, XRD and FTIR analysis have confirmed the synthesis of nano particles through microbial route. Extracellular induction of metal chelating proteins/reductase was analyzed by SDS-PAGE. Keywords: Synthesis, copper oxide nano particles, Phormidium cyanobacterium
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Liu, J., M. Pan et G. E. Spinnler. « Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM ». Proceedings, annual meeting, Electron Microscopy Society of America 51 (1 août 1993) : 1058–59. http://dx.doi.org/10.1017/s042482010015112x.
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Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.
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Hayashi, Yamato, Hirotsugu Takizawa, Yoshitaka Saijo, Tohru Sekino, Katsuaki Suganuma et Koichi Niihara. « Various Applications of Silver Nano-Particles by Ultrasonic Eco-Fabrication ». Materials Science Forum 486-487 (juin 2005) : 530–33. http://dx.doi.org/10.4028/www.scientific.net/msf.486-487.530.
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Applications of silver nano-sized metal particles were investigated for a new, ecologically friendly and economical liquid-solid (silver oxide-alcohol) system. Silver metal oxides as starting materials have merits in metal particles fabrication because these materials are decomposed only by heating in air. That is, noble metal oxide does not use thestrong reduction atmosphere. This reduction is ecologically clean because many noble metal oxides are not toxic, and because O2 is evolved during decomposition. We reduced silver metal oxides by ultrasound and fabricated silver nano metal nanoparticles at room temperature, and various applications were investigated. By choosing a suitable process and conditions, it is reasonable to expect that ultrasonic eco-fabrications can be extended to obtain various silver nano-particles containing materials.
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Okuda, M., I. Yamashita et H. Yoshimura. « Fabrication of nano-metal particles by ferrtin ». Seibutsu Butsuri 39, supplement (1999) : S175. http://dx.doi.org/10.2142/biophys.39.s175_2.
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Kowlgi, Krishna N. K., Ger J. M. Koper, Stephen J. Picken, Ugo Lafont, Lian Zhang et Ben Norder. « Synthesis of Magnetic Noble Metal (Nano)Particles ». Langmuir 27, no 12 (21 juin 2011) : 7783–87. http://dx.doi.org/10.1021/la105051v.
Texte intégralThèses sur le sujet "Metal Nano-particles"
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Gilzad, Kohan Mojtaba. « Plasmonic Effect of Metal Nanoparticles Deposited on Wide-Band Gap Metal Oxide Nanowire Substrate ». Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64762.
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The application of nanowires (NWs) in solar cells (SCs) is of great interest due to their new promising aspects established in nanoelectronics. Semiconductors associated with plasmonic metal nanoparticles (NPs) such as Silver (Ag), Gold (Au) and Copper (Cu), show enhanced performance in solid state light absorbing SCs owing to plasmonic characteristic of noble metal NPs. Plasmonic NPs presented a significant role in development of visible light harvesting for many applications such as photocatalytic materials, photodynamic in Surface Enhanced Raman Spectroscopy (SERS) and photovoltaics (PVs). Integration of plasmonic NPs in semiconductor materials have opened the routes to expand new PV systems with high efficiency light absorption. In this project, we introduce the synthesis ZnO and TiO2 NWs used as N-type semiconducting substrates and various methods for isolating plasmonic metal NPs, which are later deposited on the semiconducting substrates. Vertically aligned ZnO and TiO2 NWs arrays were grown on the fluorine-doped tin oxide (FTO) conductive glass substrates via hydrothermal method at low temperature and the plasmonic NPs were synthesized by wet chemistry procedures and finally decorated on the NW films by using electrophoretic deposition. The impact of metal NPs loaded on the ZnO and TiO2 NWs substrates was studied by means of UV-vis spectroscopy and Photoluminescence (PL) spectroscopy. The absorbance spectra of individual NPs were recorded. Remarkably, the reflectance spectra of produced samples presented an enhancement in light absorption of the substrates after uptake of NPs on the ZnO and TiO2 NWs. The optical properties of the as grown ZnO NWs films decorated with Ag NPs (I) in direct contact with substrate and (II) in presence of an Al2O3 insulating spacer layer have been investigated. Both systems exhibited an enhancement in the UV band-edge emission from the ZnO when excited at 325 nm. In contrast, the broad bend defect emission of the samples did not have a significant change compare to bare ZnO substrates. The observed results suggested that the ZnO and TiO2 NWs decorated with plasmonic nanoparticles can boost the optical properties of MOs NWs substrates and hence effectively enhance the separation of photoexcited electron-hole pairs and photo-conversion applications.
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Li, Xue. « "Cage" Nano and Micro-particles for Biomedical Applications ». Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS316/document.
Texte intégralRésumé :
Les systèmes à délivrance de médicaments sont des technologies conçues pour administrer des molécules actives de façon optimisée afin d’améliorer leurs effets thérapeutiques tout en minimisant les effets secondaires. En effet, ces systèmes permettent une libération au niveau d’une cible thérapeutique. Les particules de type «cage» ont récemment attiré une attention particulière en raison de leur capacité accrue à (co)incorporer et à protéger des molécules actives vis-à-vis de dégradations in vivo. Les cyclodextrines (CDs) sont des exemples type de molécules "cage", possédant une cavité hydrophobe et une surface extérieure hydrophile. Nous avons élaboré tout d’abord des assemblages supramoléculaires à base de CDs d'environ 100 nm par une méthode douce consistant à mélanger deux solutions aqueuses de polymères neutres : 1) polymère de β-CD et 2) dextrane greffé avec la benzophénone, molécule invitée formant des complexes d’inclusion avec les CDs. La procédure de préparation « verte» en une seule étape rend la formulation attractive, malgré sa relativement faible capacité d’encapsulation (5%pds). Afin d'améliorer cete charge, nous avons élaboré des particules hybrides organiques-inorganiques (MOFs) à base de CDs. Avantageusement, les CD-MOF comportent non seulement des cavités de CD, mais aussi de larges pores engendrés lors l’auto-assemblage de CDs. Le lansoprazole a été incorporé avec succès (23%pds) dans les CD-MOFs et nous avons montré que chaque CDs était capable d’accueillir une molécule de principe actif. Cependant, l’inconvénient majeur des CD-MOFs est leur faible stabilité en milieu aqueux, limitant leur domaine d’application. Une modification de surface est apparue donc nécessaire pour améliorer leur stabilité. Notre stratégie a été d’incorporer les CD-MOFs dans des matrices d'acide polyacrylique (PAA). Des microsphères composites d’environ 650 nm ont été élaborées avec succès et ont permis une bonne stabilité et une libération prolongée sur plus de 48 h. Avantageusement, ces particules composites n’étaient pas toxiques in vitro même à des concentrations élevées. Ainsi, nous nous sommes orientés vers l’étude comparative de MOFs plus stables dans l’eau, à base de trimesate de fer. Les MIL-100 (Fe) (Material of Institute Lavoisier) figurent parmi les premiers MOF étudiés en tant que nanomédicaments (nanoMOFs). Ces particules, parfaitement stables dans l'eau, se dégradent dans des milieux contenant des phosphates en perdant rapidement leur caractère cristallin et leurs ligands constitutifs. De façon étonnante, nous avons constaté que malgré leur dégradation, ces MOFs conservent leur taille intacte. Une analyse approfondie basée sur la microscopie de Raman a permis d’obtenir des informations pertinentes sur la morphologie et la composition chimique de particules individuelles. Ainsi, il a été montré qu’un front d'érosion délimitait nettement un cœur intact et une coquillé inorganique érodée. Cependant, ni l’encapsulation ni la modification de surface des MOFs n’altérait leur intégrité. Enfin, nous avons étudié la co-encapsulation de deux molécules actives utilisées en combinaison (amoxicilline et clavulanate de potassium) dans les nanoMOFs stables à base de MIL-100 (Fe). Les antibiotiques ont été incorporées par imprégnation et chaque molécule s’est localisée préférentiellement dans un compartiment (large ou petite cage) corroborant parfaitement les simulations par modélisation moléculaire. De plus, il a été découvert, de manière surprenante, qu’un grand nombre de nanoMOFs se localisait au voisinage des bactéries (S.aureus) dans des cellules infectées. En se dégradant dans ces cellules, les nanoMOFs contenant les antibiotiques ont réduit de manière importante la charge bactérienne intracellulaire. Ces études révèlent le potentiel des particules de type «cage» pour une incorporation efficace de molécules actives et leur libération contrôlée et ouvrent de nombreuses possibilités d’applicationDrug delivery systems are engineered technologies to administer pharmaceutical ingredients to improve their therapeutic effects, aiming at minimizing their side effects by means of targeted delivery and/or controlled release. “Cage” particles recently drew special attention since they could act as “drug containers” which potentially load large amount of drugs, improve their stability and offer the possibilities to co-encapsulate synergetic drugs. Cyclodextrins (CDs) are typical “cage” molecules with a hydrophobic cavity and a hydrophilic outer surface. Taking advantage of the host-guest interactions between β-CD and benzophenone (Bz), CD based nanoparticles (CD-NPs) were the first formulation investigated. CD-NPs of around 100 nm were instantaneously produced by mixing two aqueous solutions of neutral polymers: 1) poly-CD containing β-CDs, and 2) Bz grafted Dex (Dex-Bz). The “green” and facile preparation procedure makes it attractive formulation, whereas its limitation lies on the low drug payloads (~ 5 wt%). In order to improve the drug loading capacity of CDs, porous CD based metal organic frameworks (CD-MOFs) were synthesized, which contain not only CD cavities, but also large pores built up by CDs self-assembly. Lansoprazole (LPZ) was incorporated in CD-MOF microcrystals (~ 6 µm) reaching payloads as high as 23.2 ± 2.1% (wt). Remarkably, each CD cavity was able to host a drug molecule, offering new opportunities for the use of CD-MOFs for drug delivery purposes. However, these particles disassembled in aqueous media, which limits their application for oral and intravenous administration. Surface modification is therefore necessary to improve their stability in water. The drug loaded CD-MOF nanocrystals (~ 650 nm) were successfully embedded in polyacrylic acid (PAA) polymer matrices. The composite microspheres exhibited spherical shapes and sustained drug release over a prolonged period of time (over 48 h). Drug loaded MOF/PAA composite microspheres were not toxic in vitro (cell viability ~ 90%) even at very high concentrations up to 17.5 mg/mL. MOF/PAA composite microspheres constitute an efficient and pharmaceutically acceptable MOF-based carrier for sustained drug release. However, the process of surface modification was complicated and lead to larger particles and reduced drug payloads. Water-stable MOFs are a novel type of hybrid particles, showing a high potential as drug carriers. Iron trimesate MOFs, namely, MIL-100 (Fe) (MIL stands for Material of Institute Lavoisier) was among the first nano-scaled MOFs used for drug delivery. These particles were stable in water but degraded in phosphate buffer saline (PBS) losing their crystallinity and constitutive trimesate linkers. However, it was discovered that they kept their morphology intact. A thorough analysis based on Raman microscopy was carried on to gain insights on both the morphology and chemical composition of individual particles. It was evidenced the formation of a sharp erosion front during particle degradation. Noteworthy, the MOFs did not degrade during drug loading nor surface modification. Co-encapsulation of two synergic antibiotics (amoxicillin and potassium clavulanate) in MIL-100 (Fe) nanoMOFs was achieved following a “green” procedure by soaking nanoMOFs in aqueous solutions of both drugs. Molecular modelling showed that each drug preferentially located in a separate nanoMOF compartment. Surprisingly, nanoMOFs were prone to co-localize with bacteria once internalized in infected macrophages. NanoMOFs acted synergistically with the entrapped drugs to kill intracellular S. aureus, in vitro. These results pave the way towards the design of engineered nanocarriers in which each component synergistically plays a role in fighting the disease. These studies unravel the potential of “cage” particles for efficient drug entrapment and controlled release and open numerous possibilities for applications
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Kudo, Akira Ph D. Massachusetts Institute of Technology. « Growth mechanisms of carbon nano-fibers, -tubes, and graphene on metal oxide nano-particles and -wires ». Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104466.
Texte intégralRésumé :
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 195-208).
Carbon nanostructures (CNS) such as carbon nano-fibers (CNFs), -tubes (CNTs), and graphene are of interest for a diverse set of applications. Currently, these CNS are synthesized primarily by chemical vapor deposition (CVD) techniques, using metal catalysts. However, after CNS synthesis, those metals are oftentimes detrimental to the intended application, and extra steps for their removal, if available, have to be taken. As an alternative to metallic catalysts, metal oxide catalysts are investigated in order to better understand metal-free CVD processes for CNS synthesis. This thesis furthers the mechanistic understanding of metal oxide mediated CNS growth, especially metal oxide nanoparticles (MONPs) for CNTs, thereby addressing yield and expanding the range of known catalysts and atmospheric CVD conditions for CNS growth. CNT and CNF growth from zirconia nanoparticles (NPs) are first studied, and a technique is developed to grow CNTs and CNFs from metal NP (MNP) and MONP catalysts under identical CVD conditions. The morphologies of the catalyst-CNT and -CNF interface for zirconia NPs are found to be different than for iron or chromium NPs via high resolution transmission electron microscopy (HRTEM) including elemental and phase analyses, and evidence of surface-bound base growth mechanisms are observed for the zirconia NPs. Titania NP growth conditions are investigated parametrically to achieve homogeneous and relatively (vs. zirconia) high growth yield, where clusters of CNTs and CNFs separated by only tens of nanometers are observed. Catalytic activity of titania NPs are estimated to be an order of magnitude lower than iron NPs, and a lift-off mechanism for titania NP catalysts is described, indicating that several layers of graphene will cause lift-off, consistent with HRTEM observations of 4-5 layer graphite within the CNFs. Potential catalytic CNS activity of chromia, vanadia, ceria, lithia and alumina NPs are explored, establishing for the first time CNT growth from chromia and vanadia precursor-derived NPs, although the phases of those NPs are not determined during growth. The insights acquired from MONP-mediated CNS growth are applied to demonstrate continuous, high-yield, few-layer graphene formation on titania nanowires.
by Akira Kudo.
Ph. D.
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Washim, Hossain. « Surface Enhanced Raman Spectroscopic Study of Some Functional Molecules Adsorbed on Noble Metal Nano Particles ». Thesis, University of North Bengal, 2019. http://hdl.handle.net/123456789/2833.
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Zhang, Yuan. « Optical spectra of molecular complexes and molecular junctions coupled to metal nano-particles ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17356.
Texte intégralRésumé :
Diese Arbeit präsentiert eine vollständige quantenmechanische Beschreibung eines Systems bestehend aus einem Molekül und einem metallischem Nanopartikel (MNP) in der Gegenwart eines Strahlungsfeldes. Zuerst wird ein System aus einem Molekül und einem Gold-MNP betrachtet. Das Emissionsund Absorptionsspektrum zeigt viele scharfe molekulare Schwingungssatelliten auf einem breiten Plasmonmaximum. Eine Verstärkung der Schwingungssatelliten um drei Größenordnungen ist auf effiziente Absorption und Emission durch die MNP zurückzuführen. Dann wird ein System aus einer molekularen Kette mit einem Gold-MNP untersucht. Alle zuvor genannten Phänomene treten auch hier auf, jedoch werden die Schwingungssatelliten durch das Exzitonenband der molekularen Kette ersetzt. Anschließend wird ein Nano-Laser aus vielen Molekülen und einem Gold-MNP betrachtet. Die Moleküle werden durch inkohärentes optisches Pumpen angeregt. Dabei wird eine starke Plasmonanregung durch die gemeinsame Kopplung an die Moleküle erreicht. Die Photonenemission des Lasers zeigt, dass die Intensität ansteigt, während die Linienbreite schmaler wird. Die Korrelationsfunktion in zweiter Ordnung für die Photonen in Verbindung mit der schmaler Emission könnte dabei sogar einen Hinweis auf Lasing geben. Zuletzt wird eine Nanoverbindung aus einem Molekül und zwei sphärischen metallischen Elektroden betrachtet. Das Molekül wird durch den sequentiellen Ladungstransfer angeregt. Durch die Kopplung an die Moleküle werden die Elektrodenplasmonen angeregt. Die Photonenemission der Verbindung zeigt, dass die scharfen molekularen Schwingungssatelliten um das Tausendfache verstärkt werden. Anschließend ist ein System aus zwei pyramidalen Elektroden, die seitlich von zwei Gold-MNP eingeschlossen werden, untersucht. Hier können die Schwingungssatelliten einzeln verstärkt werden, indem der Abstand zwischen den MNP variiert wird. Wir zeigen auch, dass das Lasing in einer Verbindung aus vielen Molekülen theoretisch möglich ist.This thesis presents a unified quantum description of the combined molecule-metal nano-particle system in the presence of a radiation field. Firstly, a single molecule coupled to a gold nano-sphere is investigated. The emission and absorption spectrum show many sharp molecular vibrational satellites over one broad plasmon peak. The three orders of magnitude enhancement of the vibrational satellites is due to the great ability of the sphere to absorb and emit photons. Secondly, a molecular chain coupled to a gold nano-sphere is investigated. All the phenomena mentioned above appear also for such system, except that the vibrational satellites are replaced by the Frenkel exciton band of the molecular chain. Thirdly, a plasmonic nano-laser consisting of many dye molecules and a gold nano-sphere is considered. The molecules are initially excited by incoherent optical pump. The strong plasmon excitation of the sphere is achieved due to the concerted coupling with the molecules. The emission of the laser shows that the intensity is enlarged while the line-width is reduced. The second-order correlation function of photons together with the emission narrowing can be utilized to determine lasing operation. Finally, a nano-junction formed by a molecule and two spherical metallic leads is investigated. The molecule is excited through sequential electron transfer. The lead plasmons get excited due to the coupling with the excited molecule. The emission of the junction shows that the molecular vibrational satellites are about one thousand times enhanced by the lead plasmons. Then, a junction with two pyramidal metallic leads sandwiched by two gold nano-spheres is investigated. The simulations show that the molecular vibrational satellites can be selectively enhanced by varying the inter-sphere distance. It is also proved that the lasing can be realized by a junction with many molecules.
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Panov, Nikita. « Microwave-Assisted Solvothermal Synthesis and Optical Characterization of M(RE)F4 (M – Alkali Metal ; RE – Rare-Earth Metal) Nano- and Microscale Particles ». Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40590.
Texte intégralRésumé :
Interest in rare-earth-doped crystalline materials, e.g., M(RE)F4 (M – alkali metal, RE – rare-earth metal), featuring unique optical properties such as light upconversion and downshifting is experiencing a surge due to the broad spectrum of applications that these photonic systems are facilitating. The development of reliable synthetic methods that grant rapid access to these materials is therefore of great importance. Microwave-assisted synthesis is appealing in this regard, because microwave radiation enables rapid and uniform heating of the reaction mixture and allows for rigid control of the reaction conditions, factors that facilitate the production of high-quality materials within minutes. Surprisingly, the investigation around microwave-assisted synthesis of M(RE)F4 materials featuring upconversion and downshifting luminescence is limited. Methods that have already been developed predominately target Na-based systems, despite the evidence that the Li-based analogues also display excellent optical properties. In fact, only a single microwave-assisted approach toward a nanoscale Li-based system has been reported to date, while to my knowledge, no report of a microwave-assisted synthesis of a microscale Li-based system existed prior to the commencement of the work presented in this thesis. The challenge lies in the fact that access to Li(RE)F4 is not easily achieved through a simple substitution of the alkali metal source in the established protocols that yield Na(RE)F4; rather, a complete re-optimization of the synthesis method is required. This particular challenge was successfully addressed in this work.
Presented and discussed in Chapter 3 of this thesis is a rapid microwave-assisted solvothermal synthesis approach toward both upconverting and downshifting LiYF4:RE3+ microparticle systems. More specifically, it is detailed how the rigorous optimization of the reaction temperature/duration profile, initial reaction mixture pH, and ratio of the metal precursors was necessary in gaining control over the crystalline phase, morphology, and size of the microparticles under microwave-induced solvothermal conditions. Importantly, a materials growth mechanism involving the depletion of a Li-free crystal phase, followed by a particle ripening process is also proposed. Moreover, the versatility of the developed method is highlighted by showcasing how it can be extended toward the synthesis of other relevant Li- and Na-based M(RE)F4 nano- and microscale materials (i.e., LiYbF4, NaYF4, and NaGdF4) featuring upconversion luminescence. Lastly, potential challenges associated with microwave-assisted synthesis are discussed, and appropriate solutions are proposed.
The upconversion and downshifting luminescence of the M(RE)F4 materials attained via the developed synthesis approach is investigated in Chapter 4. The first part of the chapter provides a general assessment of the characteristic luminescence generated by the M(RE)F4 materials featuring various RE3+ dopant systems. The second part of the chapter is devoted to a much more thorough single-particle investigation of the anisotropic luminescence behaviour exhibited by the LiYF4:RE3+ microparticles via hyperspectral imaging, polarized emission spectroscopy, and optical trapping.
It is my hope that you, the reader, will find the work presented in this thesis stimulating from two vantage points – from the development of the most rapid microwave-assisted solvothermal synthesis of upconverting and downshifting M(RE)F4 nano/microscale materials reported to date, as well as from the utilization of specialized luminescence characterization techniques to provide fundamental insight into a seldom-considered luminescence property of crystalline materials such as LiYF4.
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Konrad, Alexander [Verfasser], et Alfred J. [Akademischer Betreuer] Meixner. « Nano-photonics on luminescent molecular systems and metal particles in optical sub-wavelength microresonators / Alexander Konrad ; Betreuer : Alfred J. Meixner ». Tübingen : Universitätsbibliothek Tübingen, 2016. http://d-nb.info/1198122153/34.
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Sandra, Fabien. « Elaboration de matériaux céramiques poreux à base de SiC pour la filtration et la dépollution ». Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20015.
Texte intégralRésumé :
En 1920, le moteur Diesel marque l'histoire en se faisant une place dans le milieu de l'automobile. Toutefois, malgré la révolution que représente le moteur Diesel notamment en terme de technologie (moteur à combustion interne dont l'allumage n'est pas commandé mais spontané par phénomène d'auto-inflammation (absence de bougie d'allumage)), des inconvénients majeurs subsistent, tout particulièrement au niveau environnemental et sanitaire (émission de gaz à effet de serre, prélèvement accru d'énergie fossile, impact direct sur la santé). Afin de lutter contre ces émissions, l'Union Européen à mit en place les normes EURO (depuis 1993) incitant les constructeurs automobiles à concevoir des procédés d'élimination des particules carbonées et à apporter des évolutions au niveau des motorisations. C'est dans ce contexte qu'a vu le jour la technologie Filtre à Particules initié par Peugeot en 1999 pour évoluer d'années en années jusqu'à être considérées aujourd'hui comme une avancée majeur en terme de traitement des particules Diesel. Encore aujourd'hui les problèmes d'émanations demeurent en raison des imbrûlés générés par le moteur diesel (suies, HC aromatiques polycycliques, d'oxyde de soufre, d'oxyde d'azote…). Les dégagements de particules de suies fines demeurant un problème particulièrement important au niveau de la santé. Cette thèse s'inscrit dans l'optique d'optimisation du procédé FàP en proposant l'élaboration de membrane à base de SiC supportée. Plus généralement, notre étude concerne l'élaboration de céramiques poreuses (membranes supportées et mousses) à base de silicium pour application environnementale et sanitaire (Filtration des particules fines, dépollution et séquestration de CO2).Le Chapitre I traite du contexte général de l'étude. La problématique des émissions de particules est abordée d'un point de vue sanitaire et environnemental en précisant les normes en vigueurs pour leur contrôle. La technologie FàP est décrite avant d'introduire le SiC et la voie dite des « polymères précéramiques » (PDCs). L'aspect catalytique est ensuite abordé avant de développer le principe d'élaboration de membrane SiC et leur intérêt pour une application de dépollution automobile.Le Chapitre II traite de l'élaboration de membranes SiC supportées. L'étude concerne l'élaboration d'un procédé optimale pour déposer une membrane au sein de la porosité du FàP qui modifierait les caractéristiques de porosité de ce dernier sans pour autant engendrer des répercussions néfastes sur la filtration. Le polymère précéramique, précurseur de SiC, sera alors décrit et nous étudierons sa mise en forme par la technique dite de « trempage-tirage » (dip-coating) afin d'élaborer, après pyrolyse, une membrane SiC. Cette dernière sera caractérisée par de nombreux outils expérimentaux.Le Chapitre III reprend le procédé d'élaboration des membranes de SiC élaboré dans le Chapitre II mais il proposera d'aller plus loin avec la réalisation et l'étude de catalyseurs pour la combustion des suies, et leur intégration au sein d'une microémulsion de type SiC-MxOy utilisée pour revêtir les FàP.Le Chapitre IV propose une étude sur la préparation de mousses à base de SiC. Ce chapitre d'aspect plus fondamental consistera à développer des mousses cellulaires et à porosité hiérarchisée à base des éléments silicium (Si), bore (B), carbone (C) et azote (N). Cette phase de carbonitrure de silicium et de bore (Si/B/C/N) sera élaborée par couplage de la voie PDCs avec soit des agents sacrificiels soit par réplication. Une étude préliminaire sur la séquestration de CO2 sera alors décrite pour finirSince the 90's, Diesel engines are widely used though they are criticized because of the pollution emitted. The constant updates of the Europeans norms (since 1993) concerning the diesel emissions imply a perpetual improvement of filtration techniques. The Diesel Particles Filter (DPF) technology used by the car manufacturer PSA Peugeot Citroën is one of the best ways to fulfill the limitation for diesel emissions. However, particles emission issue is still a problem and future legislations more and stricter, so an improvement of the DPF process is required to respect them. In this context, we have considered the elaboration of two different types of porous membranes on the DPF channels. The first one was in SiC, and had the aim to enhance the filtration efficiency. In this way, the smallest particles matter could be locked in the filter. The second kind of membrane integrates a catalytic phase inside the ceramic matrix, so in addition to the filtration aspect, it could improve soot combustion during the regeneration step of the DPF.The first chapter of my thesis deals with the literature corresponding to the subject, i.e. the DPF technology, non-oxides Si-based ceramics, and in particular those obtained through polymer-derived ceramics route (also called PDCs route). Then, ceramic coatings and catalytic phases are also treated. In the second chapter, we have considered the PDCs route and preceramic polymers to elaborate a SiC coating inside the DPF channels. We employed the dip-coating technique to overlay the channel surface with the AHPCS precursor of SiC (allylhydridopolycarbosilane), then, a pyrolysis under argon allows obtaining a SiC coating, in order to decrease the average pore diameter of the DPF (keeping an efficient filtration while avoiding overpressure) to catch soot nanoparticles evolving from Diesel engine.The third part of my PhD deals with the elaboration of another kind of coating for the DPF channels including a catalytic phase in the ceramic membrane. For this purpose, the microemulsion synthesis has been considered to prepare SiC-MxOy membrane. Further, we incorporated various catalytic phases based on Ce, Fe and Pt as activators of soot combustion. By employing the dip-coating technique, we successfully covered the DPF channels of our monoliths with the aforementioned microemulsion and after a heat treatment under controlled atmosphere; a porous coating consisting of the catalytic phase and the ceramic matrix was obtained. From this film, the porosity has been modified by lowering the diameter of the initial pores, but also by getting an additional porosity due to the polymer conversion and the surfactant decomposition. Catalytic sites in the ceramic have improved the soot combustion by lowering the temperature of the combustion.The fourth chapter introduces the elaboration of porous SiBCN materials through two approaches, replication and warm-pressing with sacrificial template (polymethylmethacrylate, PMMA). The SiBCN ceramic is a promising material due to its high mechanical properties and its stability at high temperature (1700-1800°C). By coupling the PDCs way with those two techniques, we are able to elaborate SiBCN porous materials which features can be tuned according to the technological application envisaged
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George, Jonathan Alan. « Development of a Plasma Arc Manufacturing Process and Machine to Create Metal Oxide Particles in Water From Wire Feedstock ». Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3494.pdf.
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Zhang, Yuan [Verfasser], Volkhard [Akademischer Betreuer] May, Kurt [Akademischer Betreuer] Busch et Andreas [Akademischer Betreuer] Knorr. « Optical spectra of molecular complexes and molecular junctions coupled to metal nano-particles / Yuan Zhang. Gutachter : Volkhard May ; Kurt Busch ; Andreas Knorr ». Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://d-nb.info/1079271554/34.
Texte intégralChapitres de livres sur le sujet "Metal Nano-particles"
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Kang, Kyung A., Bin Hong et Hanzhu Jin. « Nano Metal Particles for Biomedical Applications ». Dans NanoScience in Biomedicine, 290–313. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-49661-8_12.
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Rao, C. N. R., G. U. Kulkarni et P. J. Thomas. « Physical and Chemical Properties of Nano-Sized Metal Particles ». Dans Metal-Polymer Nanocomposites, 1–35. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2004. http://dx.doi.org/10.1002/0471695432.ch1.
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Zhang, J. Z., B. A. Smith, A. E. Faulhaber, J. K. Andersen et T. J. Rosales. « Femtosecond Studies of Colloidal Metal Nano-Particles ». Dans Ultrafast Processes in Spectroscopy, 561–65. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4615-5897-2_126.
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Ivask, Angela, Saji George, Olesja Bondarenko et Anne Kahru. « Metal-Containing Nano-Antimicrobials : Differentiating the Impact of Solubilized Metals and Particles ». Dans Nano-Antimicrobials, 253–90. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-24428-5_9.
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Joshi, Mangala, et Anasuya Roy. « Antimicrobial Textiles Based on Metal and Metal Oxide Nano-particles ». Dans Nanomaterials in the Wet Processing of Textiles, 71–111. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2018. http://dx.doi.org/10.1002/9781119459804.ch2.
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Fang, Zhen. « Metal Oxides Synthesis ». Dans Rapid Production of Micro- and Nano-particles Using Supercritical Water, 29–55. Berlin, Heidelberg : Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-12987-2_3.
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Solgi, Mousa, et Mina Taghizadeh. « Biogenic Synthesis of Metal Nanoparticles by Plants ». Dans Biogenic Nano-Particles and their Use in Agro-ecosystems, 593–606. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2985-6_27.
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Jongh, L. J., D. A. Leeuwen, J. M. Ruitenbeek et J. Sinzig. « Magnetic Properties of Metal Cluster Compounds. Model Systems for Nano-Sized Metal Particles ». Dans Magnetism : A Supramolecular Function, 615–43. Dordrecht : Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-015-8707-5_30.
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Solgi, Mousa. « Application of Biogenic and Non-biogenic Synthesized Metal Nanoparticles on Longevity of Agricultural Crops ». Dans Biogenic Nano-Particles and their Use in Agro-ecosystems, 205–20. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2985-6_12.
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Burjupati, Nageshwar Rao, R. Kandiban et Ashwin Parthasarathy. « Role of Metal Oxide Nano Particles in Improving Electrical, Dielectric and Thermal Properties of Polyethylene Nano Dielectric ». Dans Lecture Notes in Electrical Engineering, 182–93. Cham : Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-31680-8_19.
Texte intégralActes de conférences sur le sujet "Metal Nano-particles"
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Smith, Kyle C., Peter D. Gilbert, Christopher S. Polster et Timothy Fisher. « Heat Conduction in Metal Hydride Nano-Particles ». Dans ASME 2007 2nd Energy Nanotechnology International Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/enic2007-45037.
Texte intégralRésumé :
Metal hydrides hold significant potential for use in solid-state hydrogen storage through reversible chemical reactions of metal constituents and hydrogen. Managing heat loads in the system is critical to controlling system performance because a substantial amount of the energy content in hydrogen gas is released during the exothermic hydrogen uptake process, and this process must occur in only a few minutes for vehicle applications. These materials often are used in a powder form in which the initial particle size is 50–100 micrometers. However, as the material is cycled by hydriding (M+H2→MH) and dehydriding (M+H2←MH), particle size can decrease by several orders of magnitude. For the solid metal hydride phase, relative contributions of the electronic and phononic thermal conductivities are quantified with varying composition and particle size. Particle size effects are approximated by a boundary scattering term in the phononic thermal conductivity formulation. Also, the electronic contribution to thermal conductivity is estimated as a function of hydrogen content. The results reveal that overall thermal conductivity is highly material-specific. Materials with large electronic contributions in the pure metal state are relatively unaffected by particle size, while those with lower electronic contributions exhibit a substantial decrease in thermal conductivity with particle size.
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Okida, Masahito, Ken Kanomata, Nana Kameda, Norihisa Kobayashi, Katsuhiko Miyamoto et Takashige Omatsu. « Metal nano-particles manipulation by using optical multiple vortex tweezer ». Dans SPIE NanoScience + Engineering, sous la direction de Kishan Dholakia et Gabriel C. Spalding. SPIE, 2010. http://dx.doi.org/10.1117/12.862743.
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Goldschmidt, J. C., S. Fischer, H. Steinkemper, F. Hallermann, G. von Plessen, K. W. Kramer, D. Biner et M. Hermle. « Increasing upconversion efficiency by plasmon resonance in metal nano-particles ». Dans 2011 37th IEEE Photovoltaic Specialists Conference (PVSC). IEEE, 2011. http://dx.doi.org/10.1109/pvsc.2011.6185932.
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Swain, Pradyut Kumar, Ashok Kumar Sahool, Ratnakar Das et Payodhar Padhi. « Development, characterization and machining of Al and SiCp nano particles metal matrix nano composite ». Dans INTERNATIONAL CONFERENCE ON ENGINEERING AND TECHNOLOGY (IntCET 2017). Author(s), 2018. http://dx.doi.org/10.1063/1.5022951.
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Tung, K. H., et N. Xiang. « Fabrication of ordered metal nano-particles on a quantum well structure ». Dans 2010 Photonics Global Conference. IEEE, 2010. http://dx.doi.org/10.1109/pgc.2010.5706083.
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Li, Xiaochun, et Zhiwei Li. « Electroplated Si3N4 Reinforced Metal Matrix Nanocomposites ». Dans ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41104.
Texte intégralRésumé :
Permalloy NiFe matrix nanocomposite layers were electroplated on a copper substrate. The volume fraction of nano-sized Si3N4 particles in NiFe matrix was controlled by the addition of various percentages of Si3N4 particles in the NiFe electrolyte. The nanocomposite layers were analyzed by a scanning electron microscopy (SEM). Microhardness test was performed. With nano-sized Si3N4 particles in the NiFe matrix, the microhardness of NiFe was improved. The samples were then annealed at 800 °C for about 20 hours. The microhardness declined more with more Si3N4 particles in the NiFe matrix. The analysis result from Energy Dispersive Spectrometer (EDS) in the SEM showed that the hardness declination could be caused by the segregation of Si3N4 in the NiFe matrix. Finally this paper presents nanocomposite micromolds fabricated by electroplating onto polymer molds that were fabricated by micro-stereolithgraphy.
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El-Mahallawi, I. S., K. Eigenfeld, F. H. Kouta, A. Hussein, T. S. Mahmoud, R. M. Ragaie, A. Y. Shash et W. Abou-Al-Hassan. « Synthesis and Characterization of New Cast A356(Al2O3)P Metal Matrix Nano-Composites ». Dans ASME 2008 2nd Multifunctional Nanocomposites and Nanomaterials International Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/mn2008-47049.
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The present investigation studies the processing of A356 Al-Si alloy containing up to 5% vol.-% nano-sized al2o3 particles having size less than 500 nm. Composites were prepared using semi-solid casting route. To evaluate the results the alloys were further characterised by various metallurgical and mechanical characterization methods. The results showed that introducing nano-particles into semi-solid slurries promises to be a successful route for producing a new generation of cast metal matrix nano-composites (MMNCs). The nano-composites showed high strength values associated with superior ductility, low porosity content, high corrosion resistance, and improved electrical conductivity compared to the alloy without particles addition under the same casting conditions.
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Rezeq, Moh'd, Khouloud Eledlebi, Mohammed Ismail et Isra Lababidi. « Analysis of the interface barriers between nano metal particles and semiconductors substrates ». Dans 2013 IEEE 56th International Midwest Symposium on Circuits and Systems (MWSCAS). IEEE, 2013. http://dx.doi.org/10.1109/mwscas.2013.6674754.
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He, F., Q. Han, Y. C. Chen, C. Xu et L. Shao. « Study on Mechanical Properties of Al Metal Matrix Nanocomposites Processed Using Ultrasonic Vibration ». Dans ASME 2009 International Manufacturing Science and Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/msec2009-84197.
Texte intégralRésumé :
High intensity ultrasonic vibration was applied to disperse SiC nano-particles into molten A354 during solidification process to fabricate metal matrix nanocomposite (MMNCs). MMNCs: A354/SiC/1p was obtained by dispersing 1% SiC particles into the molten A354. The distribution of the nano-SiC particles in this material was investigated using scanning electron microscope. The mechanical properties of this nano composite were tested. A354/SiC/1p-T6 samples were also fabricated and tested. Mechanical properties of A354/SiC with different weight percentage of SiC particles were also investigated to find out the optimized content of particles. The results suggest that A354/SiC/0.5p-T6 with extra 15 minutes ultrasonic treatment has shown the highest mechanical properties.
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Hu, Xianguo, Yucheng Wu, Guangcheng Yuan, Peng Huang et Hefeng Jing. « Tribological Properties of Nano-Sized Molybdenum Disulfide Particles ». Dans World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63136.
Texte intégralRésumé :
This paper summarizes the tribological properties of MoS2 nano-particles with about 30 nm under different frictional conditions. By four-ball tribometer, the results showed that as the nano-MoS2 content is over 0.5 wt% the extreme pressure of lubricating oil is higher than to 30% than that of lubricating oil with same content of common MoS2. The nano-MoS2 particles can decrease the friction coefficient of lubricating oil obviously. However the results showed that their friction reductions have not obvious difference by the ring-on-block tribometer. The analyses of surface composition conducted by XPS and SEM images showed that the nanoparticles form a protective film (WO3) allowing an increase in the load capacity of rubbed pairs. The main advantage of the nanoparticles is ascribed to the release and furnishing of the nanoparticles from the valley onto the rubbing metal surface and their confinement at the interface.
Rapports d'organisations sur le sujet "Metal Nano-particles"
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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova et Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, janvier 2016. http://dx.doi.org/10.32747/2016.7604286.bard.
Texte intégralRésumé :
The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.