Literatura académica sobre el tema "Single metallic nanoparticles"
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Artículos de revistas sobre el tema "Single metallic nanoparticles"
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Ngo, Minh Quang. "Localized Surface Plasmon Resonances with Spherical Metallic Nanoparticles". Communications in Physics 28, n.º 2 (17 de julio de 2018): 115. http://dx.doi.org/10.15625/0868-3166/28/2/11037.
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In this work we review in part of our recent theoretical study on the electrical intensity enhancement in the dielectric medium surrounding metallic nanoparticles due to the effect of their localized surface plasmon resonance (LSPR). The known results in the case of a simple metallic spherical nanoparticle are presented and then extend them to the general case of complex network of the identical spherical metallic nanoparticles. For illustration, several typical lattices of identical spherical metallic nanoparticles will be treated. The findings of electrical intensity enhancements and plasmonic resonance wavelengths of the single and the network of the metallic nanoparticles are obtained based on the analytical expressions. The theoretical results were compared and shown the good agreement with simulation results. The simulation of the LSPRs and the electrical intensity enhancements was performed using the boundary element method.
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Compostella, Federica, Olimpia Pitirollo, Alessandro Silvestri y Laura Polito. "Glyco-gold nanoparticles: synthesis and applications". Beilstein Journal of Organic Chemistry 13 (24 de mayo de 2017): 1008–21. http://dx.doi.org/10.3762/bjoc.13.100.
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Glyco-gold nanoparticles combine in a single entity the peculiar properties of gold nanoparticles with the biological activity of carbohydrates. The result is an exciting nanosystem, able to mimic the natural multivalent presentation of saccharide moieties and to exploit the peculiar optical properties of the metallic core. In this review, we present recent advances on glyco-gold nanoparticle applications in different biological fields, highlighting the key parameters which inspire the glyco nanoparticle design.
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Hohenester, U. y A. Trugler. "Interaction of Single Molecules With Metallic Nanoparticles". IEEE Journal of Selected Topics in Quantum Electronics 14, n.º 6 (2008): 1430–40. http://dx.doi.org/10.1109/jstqe.2008.2007918.
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Klar, T., M. Perner, S. Grosse, G. von Plessen, W. Spirkl y J. Feldmann. "Surface-Plasmon Resonances in Single Metallic Nanoparticles". Physical Review Letters 80, n.º 19 (11 de mayo de 1998): 4249–52. http://dx.doi.org/10.1103/physrevlett.80.4249.
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Ramos Uña, Rafael, Braulio García Cámara y Ángela I. Barreda. "An Evaluation of Moderate-Refractive-Index Nanoantennas for Enhancing the Photoluminescence Signal of Quantum Dots". Nanomaterials 14, n.º 22 (14 de noviembre de 2024): 1822. http://dx.doi.org/10.3390/nano14221822.
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The use of nanostructures to enhance the emission of single-photon sources has attracted some attention in the last decade due to the development of quantum technologies. In particular, the use of metallic and high-refractive-index dielectric materials has been proposed. However, the utility of moderate-refractive-index dielectric nanostructures to achieve more efficient single-photon sources remains unexplored. Here, a systematic comparison of various metallic, high-refractive-index and moderate-refractive-index dielectric nanostructures was performed to optimize the excitation and emission of a CdSe/ZnS single quantum dot in the visible spectral region. Several geometries were evaluated in terms of electric field enhancement and Purcell factor, considering the combination of metallic, high-refractive-index and moderate-refractive-index dielectric materials conforming to homogeneous and hybrid nanoparticle dimers. Our results demonstrate that moderate-refractive-index dielectric nanoparticles can enhance the photoluminescence signal of quantum emitters due to their broader electric and magnetic dipolar resonances compared to high-refractive-index dielectric nanoparticles. However, hybrid combinations of metallic and high-refractive-index dielectric nanostructures offer the largest intensity enhancement and Purcell factors at the excitation and emission wavelengths of the quantum emitter, respectively. The results of this work may find applications in the development of single-photon sources.
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Levratovsky, Y. y E. Gross. "High spatial resolution mapping of chemically-active self-assembled N-heterocyclic carbenes on Pt nanoparticles". Faraday Discussions 188 (2016): 345–53. http://dx.doi.org/10.1039/c5fd00194c.
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The properties of many functional materials critically depend on the spatial distribution of surface active sites. In the case of solid catalysts, the geometric and electronic properties of different surface sites will directly impact their catalytic properties. However, the detection of catalytic sites at the single nanoparticle level cannot be easily achieved and most spectroscopic measurements are performed with ensemble-based measurements in which the reactivity is averaged over millions of nanoparticles. It is hereby demonstrated that chemically-functionalized N-heterocyclic carbene molecules can be attached to the surfaces of Pt nanoparticles and utilized as a model system for studying catalytic reactions on single metallic nanoparticles. The formation of a carbene self-assembled layer on the surface of a Pt nanoparticle and its stability under oxidizing conditions were investigated. IR nanospectroscopy measurements detected the chemical properties of surface-anchored molecules on single nanoparticles. A direct correlation was identified between IR nanospectroscopy measurements and macroscopic ATR-IR measurements. These results demonstrate that high spatial resolution mapping of the catalytic reactivity on single nanoparticles can be achieved with this approach.
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Jahr, Norbert, Mamuna Anwar, Ondrej Stranik, Nicole Hädrich, Nadine Vogler, Andrea Csaki, Jürgen Popp y Wolfgang Fritzsche. "Spectroscopy on Single Metallic Nanoparticles Using Subwavelength Apertures". Journal of Physical Chemistry C 117, n.º 15 (4 de abril de 2013): 7751–56. http://dx.doi.org/10.1021/jp311135g.
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Yedoti, Venkateswarlu y N. Supraja. "A Review on Algal Mediated Synthesized Metallic Nanoparticles: An Eco-Friendly Approach for Sustainable Nanotechnology". Current Journal of Applied Science and Technology 43, n.º 6 (3 de mayo de 2024): 1–10. http://dx.doi.org/10.9734/cjast/2024/v43i64381.
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The field of nanotechnology has witnessed a paradigm shift in recent years, with an increasing emphasis on eco-friendly and sustainable synthesis methods for metallic nanoparticles. Algal-mediated synthesis, an emerging and promising technique, harnesses the bioactive compounds present in algae for the green synthesis of metallic nanoparticles. This process not only offers a sustainable alternative to conventional chemical methods but also holds the potential to revolutionize various industries, including medicine, energy, and environmental remediation. Microalgae, forming a substantial part of the planet’s biodiversity, are usually single-celled colony-forming or filamentous photosynthetic microorganisms, including several legal divisions like Chlorophyta, Charophyta, and Bacillariophyta. Whole cells of Plectonema boryanum (filamentous cyanobacteria) proved efficient in promoting the production of Au, Ag, and Pt nanoparticles. The cyanobacterial strains of Anabaena flos-aquae and Calothrix pulvinate were used to implement the biosynthesis of Au, Ag, and Pt nanoparticles. This abstract provides an overview of the key aspects of algal-mediated metallic nanoparticle synthesis. Algae, as a versatile source of bioactive compounds, serve as both reducing and stabilizing agents in the nanoparticle formation process. Various types of algae, including microalgae and macroalgae, have been explored for this purpose, each with distinct biochemical profiles that contribute to the synthesis process.
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Doan-Nguyen, Vicky, Simon Kimber, Diego Pontoni, Danielle Reifsnyder, Benjamin Diroll, Xiaohao Yang, Marcel Miglierini, Christopher Murray y Simon Billinge. "Size-dependent non-space filling atomic packing in metallic nanoparticles". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 de agosto de 2014): C867. http://dx.doi.org/10.1107/s2053273314091323.
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Ni-Pd nanoparticles synthesized for CO catalysis are characterized by transmission electron microscopy and total X-ray scattering. The sizes of these nanoparticles can be tuned to size with great control over the monodispersity of the samples. The pair distribution functions of the reveal a local ordering within the highly disordered atomic structure within the nanoparticles. The PDFs show a size-dependent deviation from typical bulk face centered cubic (fcc) structure for these materials. The long-range isotropic disorder within these non-fcc nanoparticles can be fitted using an exponentially damped single-mode sine wave. Below a diameter of 5 nm, the Ni-Pd nanoparticles exhibit local ordering of atoms as found in typical icosahedral clusters. The transition from fcc to non-space filling atomic packing of icosahedral clusters in a nanoparticle is modeled to show the structural origin of the observed PDFs. Understanding this type of disorder can give insight into structure-property relations for applications in heterogeneous catalysis.
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Raza, Qadeer, M. Zubair Akbar Qureshi, Bagh Ali, Ahmed Kadhim Hussein, Behzad Ali Khan, Nehad Ali Shah y Wajaree Weera. "Morphology of Hybrid MHD Nanofluid Flow through Orthogonal Coaxial Porous Disks". Mathematics 10, n.º 18 (9 de septiembre de 2022): 3280. http://dx.doi.org/10.3390/math10183280.
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In this article, we study the novel features of morphological effects for hybrid nanofluid flow subject to expanding/contracting geometry. The nanoparticles are incorporated due to their extraordinary thermal conductivity and innovative work for hybrid nanofluids, which are assembled of aluminum oxides, Al2O3 metallic oxides, and metallic copper Cu. Cu nanoparticles demonstrate very strong catalytic activity, while Al2O3 nanoparticles perform well as an electrical insulator. The governing partial differential equations of the elaborated model are transformed into a system of nonlinear ordinary differential equations with the use of similarity variables, and these equations are numerically solved through a shooting technique based on the Runge–Kutta method. We develop a hybrid correlation for thermophysical properties based on a single-phase approach. A favorable comparison between shape and size factors for metallic and metallic-oxide nanoparticles is discussed via tables and figures. Moreover, the effect of embedding flow factors on concentration, velocity, and temperature is shaped in line with parametric studies, such as the permeable Reynolds number, nanoparticle volume fractions, and expansion/contraction parameters. The fluid velocity, temperature, and concentration are demonstrated in the presence of hybrid nanoparticles and are discussed in detail, while physical parameters such as the shear stress, flow of heat, and mass transfer at the lower and upper disks are demonstrated in a table. The hybrid nanoparticles show significant results as compared to the nanofluids. If we increase the nanoparticle volume fraction, this increases the thermal performance for an injection/suction case as well. The above collaborative research provides a strong foundation in the field of biomedical equipment and for the development of nanotechnology-oriented computers.
Tesis sobre el tema "Single metallic nanoparticles"
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Fu, Xingjie. "Synergy between photoswitchable fluorescent proteins and metallic nanoparticles : a combination of theoretical and experimental studies at ensemble and single particle level". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2023/2023ULILR070.pdf.
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Les protéines fluorescentes réversiblement commutables (RSFP), caractérisées par une photocommutation d'un état non fluorescent (Off) à un état fluorescent (On), sont des outils précieux pour une variété d'applications en imagerie biologique, en particulier dans les microscopies de fluorescence super-résolues tel que le RESOLFT. Les propriétés photochromiques et photophysiques des RSFP, telles que les coefficients d'extinction molaire, le rendement quantique de fluorescence, la récupération thermique et le rendement quantique de photocommutation, sont essentielles car elles définissent le contraste de commutation et la résolution maximale théorique, et elles sont également liées à la luminosité, au contraste des images et à la vitesse d'acquisition des images dans ces microscopies. Dans cette thèse, nous nous concentrons sur la rsEGFP2 qui est une RSFP particulière utilisée en RESOLFT. Alors que la mutation ciblée ou aléatoire est la technique générale pour moduler les propriétés des RSFP, cette thèse démontre qu'en utilisant l'effet plasmonique, il est possible de modifier et d'optimiser les propriétés photophysiques de la rsEGFP2. Dans la littérature il existe une grande divergence en ce qui concerne les valeurs de fluorescence et de rendement quantique de commutation de rsEGFP2. Nous avons tout d'abord déterminé la dépendance de la fluorescence et du rendement quantique de commutation par rapport à la température pour rsEGFP2. Pour le rendement quantique de commutation, nous avons développé une nouvelle expérience économique pour suivre l'évolution de l'absorbance à différentes températures sous irradiation continue. En tenant compte pour la première fois de l'ensemble des paramètres influents (rendement de commutation, constantes de retour thermique, coefficient d'extinction de toutes les espèces absorbantes) et avec une évaluation précise de la marge d'erreur, nous avons déterminé les valeurs du rendement quantique de commutation On-to-Off et Off-to-On à des températures spécifiques. Nous avons constaté qu'à 37°, le retour thermique a un impact important sur les valeurs de rendement quantique. En outre, les rendements quantiques de la photocommutation On-to-Off et Off-to-On dépendent de la longueur d'onde d'irradiation et de la température, tandis que le rendement quantique de la fluorescence diminue d'environ 30 % par rapport à la température ambiante. Par conséquent, nous proposons un nouveau schéma photodynamique avec deux espèces différentes à l'état fondamental, une espèce non émissive qui contrôle la commutation On-to-Off et une espèce émissive qui contrôle la luminosité. Nous avons également calculé la dépendance de la taille et de la forme des propriétés plasmoniques de nanoparticules d'or et d'argent afin de trouver les bons candidats pour moduler la fluorescence et le rendement quantique de commutation de rsEGFP2. Le facteur clé réside dans leurs différentes propriétés de diffusion et d'absorption. Nous avons donc synthétisé des nanoparticules d'argent et des nanobatônnets d'or de 100 nm de diamètre. L'argent donne une bande SPR à 450 nm tandis qu'elle est à 540 nm pour l'or. Des études de ces nanoparticules seules ou intégrées dans un polymère (PVA) contenant le rsEGFP2 ont été réalisées. À l'aide d'un microscope FLIM, nous avons mesuré les traces temporelles d'intensité et la durée de vie de la rsEGFP2 à proximité et à distance des nanoparticules métalliques pour examiner l'effet plasmonique. Nous avons constaté que le contraste de commutation et la luminosité de la rsEGFP2 peuvent être améliorés par les nanoparticules d'argent, alors qu'aucune modification significative n'a été observée dans le cas de l'or, ce qui peut s'expliquer par le calcul du rapport entre les sections transversales de diffusion et d'absorption de la diffusion et de l'absorption. Dans l'ensemble, nos résultats ouvrent une nouvelle voie pour contrôler les propriétés photophysiques des RSFP pour l'imagerie à super-résolutionReversibly switchable fluorescent proteins (RSFP), characterized by a photo-switching from a non-fluorescent (Off) to a fluorescent (On) state, are valuable tools to a variety of applications in biological imaging especially in super-resolved fluorescence microscopies. The photochromic and photophysical properties of RSFPs such as molar extinction coefficients, fluorescence quantum yield, thermal back recovery and photo-switching quantum yield are essential as they impose the switching contrast and theoretical maximum resolution, and they are also linked to the brightness, contrast of images and imaging acquisition speed in these microscopies. In this thesis we focus on rsEGFP2 which is a peculiar RSFP used in the reversible saturable optical fluorescence transition (RESOLFT) method, a super-resolved microscopy technique that allows significant reduction in the illumination intensities and in photobleaching. While targeted or random mutation is the general technique to modulate properties of RSFPs, this thesis is demonstrating that using plasmonic effect and enhancement of electromagnetic field of specific metal nanoparticles, it is possible to change and optimize the photophysical properties of rsEGFP2. In literature, there is a large discrepancy about fluorescence and switching quantum yield values of rsEGFP2. In addition, these values are usually given at room temperature, which are different from the temperature setting for in-vivo studies. Therefore, we firstly determined the temperature-dependence of fluorescence and switching quantum yield temperature-dependence for rsEGFP2. For the switching quantum yield we developed a new budget-friendly experiment to follow the evolution of absorbance at different temperature under continuous irradiation. Taking into account for the first time the full set of influencing parameters, i.e., dependence of switching yield on irradiation wavelengths, influence of the thermal back recovery rate constants, the extinction coefficient of all absorbing species, and with an evaluation of robustness and error propagation, we determined On-to-Off and Off-to-On switching quantum yield values under specific temperatures. We found that at 37° the thermal recovery has a strong impact on the determination of the quantum yield values. Moreover, the photo-switching quantum yields in both On-to-Off and Off-to-On directions is dependent on irradiation wavelength and on temperature dependent with varied degrees, while the fluorescence quantum yield decrease about 30% in comparison to room temperature. Therefore, we propose a new photodynamics scheme with two different On-state ground state species, i.e., a non-emissive one that controls the On-to-Off switching and an emissive one the brightness. Then, we calculated the size and shape dependence of the plasmonic properties of gold and silver nanoparticles to find the good candidate for modulating fluorescence and switching quantum yield. The key factor behind the different outcomes by plasmonic nanoparticles lies in their different scattering and absorption properties. Based on the simulation, we synthesized 100 nm diameter silver nanoparticle and gold nanorods. The silver nanoparticle has a SPR band at 450 nm while it is at 540 nm for the gold ones. Preliminary studies of these nanoparticle alone or embedded within a polymer (PVA) containing rsEGFP2 were performed. Using a FLIM microscope, we measured the intensity time traces and lifetime of rsEGFP2 near and away from metallic nanoparticles to examine the plasmonic effect. We found that both switching contrast and the brightness of rsEGFP2 could be improved by silver nanoparticles, while no significant modification of rsEGP2 properties was observed in the case of gold nanorods which can be explained with the calculation of ratio between the scattering and absorption cross sections. Altogether our results open a new way to control RSFPs photophysical properties for super-resolution imaging
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Panais, Clément. "Ultrafast energy transfers at the nanoscale : cooling and vibrational dynamics of single supported metal nano-objects". Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10251.
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Ce travail de thèse porte sur l'étude optique des propriétés thermiques et vibrationnelles de nano-objets métalliques. Deux techniques optiques opérant à l’échelle du nano-objet unique (la spectroscopie par modulation spatiale et la spectroscopie pompe-sonde résolue en temps) ont été utilisées pour localiser des nanodisques d’or individuels déposés aléatoirement sur un substrat solide, caractériser leurs propriétés optiques et étudier leur dynamique ultrarapide. La première partie de ce travail décrit l'étude optique du refroidissement de nanodisques d'or colloïdaux déposés sur des substrats de différentes compositions et épaisseurs, complétée par des simulations numériques. Les expériences et simulations réalisées ont démontré que la dynamique thermique, régie par le transfert thermique à l'interface nanodisque-substrat et la diffusion de la chaleur dans le substrat, dépend fortement des caractéristiques du substrat, avec notamment un ralentissement marqué dans le cas de membranes nanométriques. La deuxième partie de ce travail a permis de caractériser la réponse optique transitoire d’un nanodisque d’or unique induite par sa dynamique thermique. Une forte dépendance de la sensibilité des mesures optiques à l’échauffement du nanodisque vis-à-vis de la longueur d'onde du faisceau lumineux utilisé pour sonder cet échauffement a pu être démontrée et quantifiée. Une dépendance de la dynamique temporelle des signaux optiques mesurés en fonction de la longueur d’onde de sonde a également été observée dans la gamme spectrale où la contribution de l’échauffement de la membrane n’est pas négligeable devant celle associée à l’échauffement du nanodisque, et a pu être reproduite quantitativement par un modèle thermo-optique. La dernière section de cette thèse se concentre sur l'étude des propriétés vibrationnelles de nanodisques d'or uniques. Les expériences menées ont permis de confirmer la dépendance marquée des facteurs de qualité vibrationnels de nano-objets déposés vis-à-vis de leur morphologie, démontrée dans des travaux antérieurs. En particulier, des facteurs de qualité améliorés ont été observés pour des nanodisques avec des rapports diamètre/épaisseur compris entre 2 et 5. La sensibilité des signaux optiques mesurés aux vibrations d’un nanodisque a également été mesurée. Elle dépend fortement de la longueur d'onde de la sonde, tout en présentant une forme spectrale très différente de celle de la sensibilité optique à l’échauffement du nanodisque. Ce travail de recherche a ainsi permis de mieux comprendre les dynamiques de refroidissement et vibrationnelle de nanodisques d’or individuels déposés sur des membranes d’épaisseur nanométrique, et de quantifier précisément la sensibilité des signaux mesurés par spectroscopie optique pompe-sonde à ces dynamiques. Des travaux ultérieurs pourraient se focaliser sur l’étude de nanoparticules déposées sur des membranes de composition différente et plus favorable à la mise en évidence de modalités non-diffusives de transfert thermique, ou encore chercher à préciser la nature des phénomènes internes d’amortissement vibrationnels, qui déterminent les facteurs de qualité vibrationnels des nano-objets en l’absence de couplage avec l’environnementThis thesis work focuses on the optical study of the thermal and vibrational properties of metallic nano-objects. Two optical techniques operating at the scale of a single nano-object (spatial modulation spectroscopy and time-resolved pump-probe spectroscopy) were used to localize single gold nanodisks randomly deposited on a solid substrate, characterize their optical properties, and study their ultrafast dynamics. The first part of this work describes the optical study of the cooling of colloidal gold nanodisks deposited on substrates of different compositions and thicknesses, complemented by numerical simulations. Experiments and simulations demonstrated that the thermal dynamics, governed by thermal transfer at the nanodisk-substrate interface and heat diffusion in the substrate, strongly depend on the characteristics of the substrate, with a significant slowdown in the case of nanometric membranes. The second part of this work allowed to characterize the transient optical response of a single gold nanodisk induced by its thermal dynamics. A strong dependence of the sensitivity of the optical measurements to nanodisk heating on the wavelength of the light beam used to probe this heating was demonstrated and quantified. A dependence of the temporal dynamics of the measured optical signals on the probe wavelength was also observed in the spectral range where the contribution of the heating of the membrane is not negligible compared to that associated with nanodisk heating, and was quantitatively reproduced by a thermo-optical model. The final section of this thesis focuses on the study of the vibrational properties of single gold nanodisks. The experiments carried out allowed to confirm the strong dependence of the vibrational quality factors of deposited nano-objects on their morphology, demonstrated in previous work. In particular, improved quality factors were observed for nanodisks with a diameter/thickness ratios between 2 and 5. The sensitivity of measured optical signals to the vibrations of a nanodisk was also measured. It strongly depends on the probe wavelength, while presenting a very different spectral shape from that of optical sensitivity to nanodisk heating. This research work has thus led to a better understanding of the cooling and vibrational dynamics of single gold nanodisks deposited on nanometer-thick membranes, and has allowed to precisely quantify the sensitivity of signals measured by optical pump-probe spectroscopy to these dynamics. Future work could focus on studying nanoparticles deposited on membranes of different compositions that are more favorable for demonstrating non-diffusive modes of heat transfer, or investigate the nature of internal vibrational damping phenomena, which determine the vibrational quality factors of nano-objects in the absence of coupling with the environment
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Nahle, Sara. "Réponse macrophagique aux nanomatériaux carbonés : effets de leur caractéristiques physiques et chimiques sur le transcriptome Carbon-based nanomaterials induce inflammation and autophagy in rat alveolar macrophages Single wall and multiwall carbon nanotubes induce different toxicological responses in rat alveolar macrophages Gene expression profiling of alveolar macrophages exposed to non-functionalized, anionic or cationic multi-walled carbon nanotubes shows three different mechanisms of toxicity Cytotoxicity and global transcriptional responses induced by zinc oxide nanoparticles NM 110 in PMA-differentiated THP-1 cells Protein and lipid homeostasis altered in rat macrophages after exposure to metallic oxide nanoparticles". Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0142.
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Les nanomatériaux carbonés (NMC) sont très utilisés dans le monde industriel et leurs applications, nombreuses, sont en plein développement. L’absence de réglementation pour leur préparation et leur emploi fait qu’il est nécessaire comme pour tous les nano-objets, de déterminer le risque qu’une exposition fait courir à l’Homme et d’adapter la législation en conséquence. Une meilleure connaissance de leur potentiel toxique est donc nécessaire. Les difficultés de plus en plus grandes pour utiliser les modèles animaux, rend nécessaire le développement d’études avec des lignées cellulaires au sein desquelles les macrophages ont une place prépondérante. Ces NMC sont très légers et forment facilement des aérosols et les modèles préférés sont les macrophages alvéolaires. Cependant il n’existe pas à l’heure actuelle de lignées de macrophages alvéolaires humains à la différence de cellules de rat. Le sujet de ma thèse porte sur l’étude de la réponse macrophagique aux NMC et la compréhension des effets de leurs caractéristiques physiques et chimiques sur leur transcriptome. Les NMC étudiés sont les nanotubes de carbone (NTC) multi feuillets, les NTC mono feuillets, le noir de carbone et l’oxyde de graphène. Nos résultats montrent que tous les NMC étudiés déclenchent une réaction inflammatoire dans les cellules NR8383 et les cellules THP-1 différenciées, et certains d’entre eux induisent une cytotoxicité importante. La taille, la fonctionnalisation et la forme contrôlent les mécanismes de toxicité induits par les NMC. Des NTC de tailles similaires altèrent des voies de signalisation identiques, une fonctionnalisation par des groupements amines produit un stress des lysosomes tandis que la fonctionnalisation par des groupements carboxyle entraine un stress du réticulum endoplasmique (RE). Les nanotubes induisent une désorganisation du cytosquelette plus importante que les nanoparticules sphériques. Nous avons également mis en évidence une accumulation de lipides chez les cellules NR8383 suite à un stress du RE induit par le Mitsui-7, un NTC multi feuillet. Le même NTC induit aussi une fusion de ces macrophages. La formation de ces cellules spumeuses et des cellules géantes à multi-noyaux sont des évènements clés entrainant la formation de granulomes. Les résultats obtenus présentent un support important pour la compréhension des effets des NMC montrant une certaine toxicité non négligeable de point de vue moléculaire. Cette toxicité est dépendante des caractéristiques physiques et chimiques de ces nanomatériaux. Ainsi, en se basant sur ce type de données, on pourra s’orienter vers une fabrication safe-by-design pour limiter les risques liés à leur expositionCarbon nanomaterials (CNM) are widely used in the industrial world and they have many applications. The absence of legislation controlling their preparation and uses makes necessary, as for all nano-objects, the study of their toxicity in order to determine the risk of human exposure and to adapt legislation accordingly. Therefore, a better knowledge of their toxic potential is necessary. The increasing difficulties in using animal models make necessary the development of studies using cell lines especially macrophages that play a predominant role. These CNM are very light and form easily aerosols, reason why the preferred models for toxicity studies are alveolar macrophages. However, there are no human alveolar macrophage lines currently but rat cells exist. The subject of my thesis is to study macrophages response to CNM and the understanding of the effect of their physical and chemical characteristics on the transcriptome. The CNM studied are multiwall carbon nanotubes (CNT), single wall CNT, carbon black and graphene oxide. Our results show that all CNM studied trigger an inflammatory reaction in NR8383 and differentiated THP-1 cells, also some of them induce cytotoxicity. Size, functionalization and form control CNM toxicity mechanisms: CNT with similar size alter identical signaling pathways, amino group functionalization produces lysosomal stress, whereas functionalization with carboxyl groups causes reticulum endoplasmic (RE) stress, nanotubes induce cytoskeleton disorganization more than spherical nanoparticles. Otherwise, we identified lipid accumulation in NR8383 cells due to RE stress induced by Mitsui-7, a multiwall CNT. There was also a fusion of these macrophages. The formation of these foam cells and giant multi-nucleus cells are key events leading to granulomas formation. The results obtained are an important support for understanding CNM effects, showing some significant toxicity at molecular level. This toxicity is dependent on the physical and chemical characteristics of these nanomaterials. Thus, based on this type of data, we can move towards a safer manufacture to avoid the risks associated with their exposure
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Chen, Jeng-Hong y 陳建宏. "Study on Enhancement of Single Molecule FluorescenceUsing Metallic Nanoparticles". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/99316931193709299290.
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碩士國立臺灣大學
應用力學研究所
96
Electromagnetic field of gold and silver nanoparticles under plane wave and electric dipole incident are investigated. By using Maxwell’s equation and multi-multipole method, a set of linear equations of expansion coefficients is first constructed by satisfying boundary condition pointwisely. Singular value decomposition is then used to solve the overdetermined liner equations. Study on coupling of single fluorescent molecule and metallic (solid and core-shell) nanoparticles . Under plane wave incident, the local electric field would be arose and let the molecule reaching excitation stage and liberating fluorescence. We use a electric dipole to simulate single fluorescence molecule. By working with metallic nanoparticles, the molecule would have fluorescence enhancement of single molecule. Then we use the strong electric local field from two metallic nanoparticles to excite the molecule. We demonstrate that it would generate the better enhancement. And the maximum enhancement is achieved when the emission frequency is red-shift from the surface plasmon resonance of the particles.
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Johnson, Monique Erica. "Determination of Metallic Constituents in Environmental and Biological Materials". 2012. https://scholarworks.umass.edu/open_access_dissertations/648.
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Studies of the interaction of the relevant metal, metalloid or nanoparticulate species with biological systems are underpinned by the provision of reliable information about chemical composition of the relevant materials. Often, no methods of chemical analysis are available. The work described in this dissertation centers on developing methods to help with studies for a variety of analytes and samples. A method was developed for the determination of 11 trace elements (As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Pb, Ti, and Zn) in human breast milk and infant formulas by inductively coupled plasma optical emission spectrometry (ICP-OES) following microwave-assisted digestion. A method was established for the determination of trace elements, with an emphasis on titanium as titanium dioxide, in snack foods and consumer products. The interactions of some dissolved metals, including rare earth elements, and metallo-nanoparticles (silver, gold, titanium dioxide, aluminum oxide, and iron) with aquatic plants were studied. After exposure in a variety of mesocosms, the partitioning of the elemental species between various compartments was quantified by ICP-MS and ICP-OES following microwave-assisted digestion. An ICP mass spectrometry (MS) method has also been developed to quantify the uptake of gold and silver nanoparticles by C. elegans. Uptake of gold nanoparticles was size dependent, suggesting increased ingestion efficiency with increased particle diameter. The feasibility of discriminating between suspended TiO2 nanoparticles and dissolved titanium by the analysis of the rapid transient signal events obtained from the ICP-MS instrument operated in a rapid response mode was also developed. Data handling parameters were established that allowed a distinction in the signals for nanoparticulate and standard solutions. Spikes in the signal were defined by distinct parameters using the mean and standard deviation, where a spike in the signal was defined as a signal > + ks (k =3). This approach however did lead to a statistical difference in the spike signal events for solutions and nanosuspensions.
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Ritacco, Tiziana, Vincenzo Carbone, Michele Giocondo y Pasquale Pagliusi. "Physical processes in single and multiple photons additive nano-manufacturing of three-dimensional polymeric and metallic structures for advanced optics". Thesis, 2018. http://hdl.handle.net/10955/1862.
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Dottorato di Ricerca in Scienze e Tecnologie Fisiche, Chimiche e dei Materiali. Ciclo XXXIn the field of nanotechnologies the Two-Photons Direct Laser Writing (TP-DLW) is the most advanced optical technique for creating arbitrarily complex 3D structures in organic resists, featuring details down to 50 nm, well below the diffraction limit. More recently, this technique has been used in “resists” containing a photosensitive metallic precursor, activated by the two-photon absorption (TPA) process, allowing for the creation of metallic nanoparticles clusters inside to the focus figure of a highly focused laser beam, where the TPA threshold intensity is reached. The aim of my PhD work was the elucidation of the physical processes involved in the realization of 3D nanostructures made in different materials for applications in micro-fluidics and advanced optics. In particular, I carried out studies on both isotropic and anisotropic photoresists, and on metallic precursors. Concerning the isotropic photoresists, I have investigated the capabilities and the limits of the TP-DLW technique, on the fabrication of microfluidic systems and elements of millimetric size, with micro- and nano-features printed inside the channels. The best results in printing such millimetric structures in terms of geometrical compliance and fabrication time are achieved, by combining the single (SPA) and the two-photon absorption (TPA) processes. The latter one allowed for the creation of a shell, an internal structural scaffold and eventual microscopic details, whereas the former one to polymerize the bulk of the object. However, the development step of microfluidic systems (i.e. the removal of the un-polymerized resist) is quite challenging in general, due to possible swellings and consequent distortions in the structure geometry. In my PhD, I developed an effective protocol to face this issue. The application of the TP-DLW technique to anisotropic reactive mesogens (RMs) resulted in very interesting achievements, as it allowed for the fabrication of 3D solid structures, maintaining the optical properties of liquid crystals, in combination with the mechanical properties of polymers. Effects of the direct laser writing on the internal molecular order of the reactive mesogens have been thoroughly investigated, to ensure a fine control on the optical properties of 3D objects made in liquid crystalline elastomers. Analyses of the physical processes, which occur during TP-DLW and allow for tuning of the optical response of the printed 3D solid structures are shown. Appropriate doping of the reactive mesogens with dyes and chiral dopant agents were performed to investigate different fields of applications. In particular, a chiral agent confers helical order to the RMs, which show selective Bragg reflection of the impinging light in both wavelength and polarization. Micro-fabrication of 3D chiral structures is a brand new field that is paving the way to the creation of photonic devices, such as micro-laser of defined shape, white light reflective object, anti-counterfeiting and data storage systems. I performed a series of experiments aimed at demonstrating the possibility to manipulate the helical structural order of the liquid crystals during TP-DLW. As a consequence, multi-colour three-dimensional structure can be created. Finally, the possibility to include metallic details in polymeric objects or even to create metallic structures would pave the way for the DLW of metallic/polymeric nano-composites. I performed experiments with polymeric or hydrogel matrices doped with a suitable metallic precursor, in a free surface drop cast, or in cell segregated thin film, onto a glass substrate. In such system, I was able to create 1D gratings made of GNPs stripes with single or multiple laser sweep. I demonstrated that the stripe width increases with the laser power and the exposure time, showing a behaviour similar to the photo-polymerization, as expected. I also analysed the influence of the exposure time over the nano-particles size distribution and density and showed that by suitably adjusting the exposure time it is possible to maximize the occurrence of a given diameter. The experiments were aimed at elucidating the involved physical phenomena, beyond the bare optical absorption. In particular, the key-role of thermal and diffusive processes have been analysed. TPA leads to the photo-reduction of ions of AuCl4 – and the creation of GNPs, but to a local heating of the sample as well. Due to the very fast heating, a thermal shock-wave is generated and is responsible of the local dehydration in the spot area. Due the concentration gradients of the ions of gold precursor and of water, different diffusive processes take place, occurring on different timescales. Therefore, different characteristic times are observed for the ion and the water diffusion, in the polymeric matrix. My experiments demonstrate that the diffusive effects can be exploited for controlling the NPs density and size when a given energy dose is delivered in multiple shots, by tuning the time interval between each shots. Preliminary experiments on the possibility to control the growth of GNPs through the application of specific electric field during TP-DLW were performed as well. Last but not least, the possibility to use TP-DLW of metal precursor to realize smart platform rich in GNPs suitable to different application is shown. In particular, I demonstrate that, controlling the pitch and the size of GNPs stripes, it is possible to create both thermo-platform whose thermal response to external light is tuneable, and detecting substrates for Surface-Enhanced Raman Spectroscopy (SERS). The Raman spectra were recorded from samples immersed in a solution of rhodamine-6G (R6G), as well as, after exposure of the samples in xylene. SERS enhancement factors of up to ~104 were obtained for both rhodamine-6G and xylene.
Università della Calabria
Capítulos de libros sobre el tema "Single metallic nanoparticles"
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"Catalysis by Metallic Nanoparticles". En Nanoscopic Materials: Size-Dependent Phenomena and Growth Principles, 327–68. 2a ed. The Royal Society of Chemistry, 2014. http://dx.doi.org/10.1039/bk9781849739078-00327.
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Catalysis means reducing the activation energy of an elementary reaction step. This requires chemical interaction of the reactant with the catalyst and continuous energy optimisation of both reaction intermediate and catalyst, along the reaction path, in the same way as it is done in quantum chemical calculations. Fluxionality of the atoms and electrons in the vicinity of the catalytic bond therefore supports the reaction. The availability of electrons to form the catalytic bond can be influenced in many ways, e.g. by catalyst particle size, alloying, co-adsorption, support interaction, charging, or application of an electrochemical potential. For optimum activity this bond should be neither too strong nor too weak. Corner and edge atoms or surface defects of the catalyst are often more active than ideal single crystal surface atoms. This means that catalytic bond strength and catalytic activity can be tuned by the particle size and shape, and by specific alloying.
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Jahan, Israt. "Phyto-Nanofabrication". En Handbook of Research on Green Synthesis and Applications of Nanomaterials, 51–76. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-8936-6.ch003.
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Green synthesis of metallic nanoparticles through natural entities (i.e., bacteria, actinomycetes, yeast, fungus, microalgae, seaweed, plants, and plant-derived materials) has become an advantageous and ecofriendly approach. However, phytocompounds of plant extract have achieved huge attention since by utilizing them high yield NPs with desirable size and shape, which can be produced through single-step synthesis scheme. Plants retain diverse biochemicals that exhibit strong hyper-accumulating potential, crucial for metallic ion reduction to metallic NPs, like platinum, gold, silver, titanium oxide, iron oxide, copper oxide, zinc oxide, palladium, etc. Here, previously published studies were reviewed for providing the latest scientific evidence on biosynthesis of metal and metal oxide NPs using different plant materials, especially medicinal plants and food and agro-wastes.
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Salagare, Shridevi, S. Ashoka y Prashanth S. Adarakatti. "Surfactant-based Electrochemical Sensing and Bio-sensing: Safety and Toxicity". En Surfactant-based Sensors in Chemical and Biochemical Detection, 94–113. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781837671182-00094.
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Due to their distinctive structures, which consist of two different molecular portions and a great variety of options, surfactants are widely utilized in various industrial products, including detergents, medications and anti-corrosive treatments. In numerous research domains, particularly in nanotechnology, surfactants have made a substantial contribution as well. For instance, the amphiphilic properties of surfactants have been used to stabilize hydrophobic nanoparticles in water, opening access to a wide range of solution-processed nanomaterial-based scalable applications. Surfactants have a significant role as an ingredient in the creation of well-controlled nanoparticles. The development of colorimetric sensors, which are of enormous interest in many interdisciplinary applications due to their simplicity, practical applicability, cost-effective production, high stability, and high selectivity, has been made possible by surfactant-assisted metallic nanoparticle production. In order to maximize the sensitivity and selectivity of the sensor, surfactants that are added during nanoparticle synthesis are essential since they have a direct impact on the characteristics of the nanoparticle characteristics. A new class of magnetic surfactants has also been introduced for use in drug delivery applications. In this chapter, we provide an overview of the fundamentals of surfactants and their applications for the development of nanotechnology.
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Harshini, Sharan. "Synergistic effects in MXene: Transition metal chalcogenides to unlock supercapacitor potential". En Materials Research Foundations, 145–67. Materials Research Forum LLC, 2024. http://dx.doi.org/10.21741/9781644903292-7.
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The foremost nations and scientific circles are focusing the spotlight mainly on energy because of the shifting global environment. The development and upgrade of energy storage systems featuring higher efficiency have drawn a great deal of concern. Therefore, significant advancements in energy storage might be made possible by a high-power density device called a supercapacitor (SCs). The use of 2D layered materials has sparked a lot of attention in the modern era since these materials have suitable electrochemical and physiochemical properties that make them ideal for high-performance energy storage devices. Amidst several 2D materials, MXenes have garnered significant interest due to their hydrophilic nature, metallic conductivity, rich active sites, and high surface area. In virtue of these upsides, compositing MXene with electrochemically favourable Ternary Metal Chalcogenides (TMCs) electrode material will significantly improve the composite performance by reducing the agglomeration of nanoparticles and inhibit restacking of MXene sheets through synergistic effects. This chapter mainly focuses on the MXene-TMCs composites for supercapacitor application and discusses the process involving them.
Actas de conferencias sobre el tema "Single metallic nanoparticles"
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Butet, J., G. Bachelier, J. Duboisset, F. Bertorelle, I. Russier-Antoine, C. Jonin, E. Benichou y P. F. Brevet. "Second harmonic generation of single metallic nanoparticles". En SPIE BiOS, editado por Jörg Enderlein, Zygmunt K. Gryczynski y Rainer Erdmann. SPIE, 2011. http://dx.doi.org/10.1117/12.874930.
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Szczech, John B., Constantine M. Megaridis, Jie Zhang y Daniel Gamota. "Ink Jet Processing of Metallic Nanoparticle Suspensions for Electronic Circuitry Fabrication". En ASME 2003 1st International Conference on Microchannels and Minichannels. ASMEDC, 2003. http://dx.doi.org/10.1115/icmm2003-1104.
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A novel approach in creating circuit electrodes with features as fine as 100 μm is demonstrated using a single 38 μm diameter orifice, piezoelectrically driven print head to deposit metallic nanoparticle suspensions. The suspensions consist of gold particles of ∼20 nm diameter suspended in toluene solvent. The amount of gold nanoparticles present in the suspension is 30% wt. Inductor and capacitor electrode patterns are deposited onto a glass substrate and thermally processed at 300°C for 15 minutes to drive off the solvent and allow the nanoparticles to sinter, thereby yielding a conductive path with a resistivity of O(10−7) Ω m.
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Kesarwani, Rahul, Harsh Chaturvedi y Alika Khare. "Plasmonic interaction between copper nanoparticles and metallic single walled carbon nanotubes". En International Conference on Fibre Optics and Photonics. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/photonics.2016.p1a.18.
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Ando, Jun. "Multicolor tracking of single biomolecules with metallic nanoparticles at microsecond time resolution". En Biomedical Imaging and Sensing Conference, editado por Osamu Matoba, Yasuhiro Awatsuji, Yuan Luo, Toyohiko Yatagai y Yoshihisa Aizu. SPIE, 2021. http://dx.doi.org/10.1117/12.2615669.
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Castanié, E., M. Boffety, R. Carminati y Dmitry N. Chigrin. "Single molecule fluorescence quenching by metallic nanoparticles: crossover between macroscopic and microscopic interactions". En THEORETICAL AND COMPUTATIONAL NANOPHOTONICS (TACONA-PHOTONICS 2009): Proceedings of the 2nd International Workshop. AIP, 2009. http://dx.doi.org/10.1063/1.3253917.
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Honarmandi, Peyman. "Fabrication of Single-Crystal Nanospherical Hydroxyapatite Powder for Biomedical Applications". En ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13326.
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The competence and compatibility of biomaterials is always challenging and demanding in biotech industries. Hydroxyapatite (HAp) is a useful biomaterial for biological applications due to its especial properties. In this paper, a dry mechanochemical process is introduced to produce hydroxyapatite nanoparticles. Structural and morphological properties of HAp powder are studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the single-crystal HAp nanospherical particles are successfully produced during milling process. Two different metallic and polymeric vials are applied and the results are compared for both vials. The results verify that the HAp nanoparticles are single crystal and their sizes are in the ranges of 12–24 nm.
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Alam, Taosif y M. Ruhul Amin. "A Numerical Model of Microstructure Formation Considering Nanoparticle Distribution During Selective Laser Melting Process". En ASME 2023 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/imece2023-110694.
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Abstract Selective laser melting (SLM) is a popular metal additive manufacturing technique that allows the development of new metal matrix nanocomposites by fusing metallic powders with nanoparticles. In the current study, a novel numerical model was proposed to simulate microstructure formation considering local nanoparticle distribution during the SLM process. The proposed model formulates a three-dimensional computational fluid dynamics (CFD) model with Lagrangian particle tracking to simulate a single-track, single-layer SLM process of aluminum alloy reinforced with TiB2 nanoparticles in ANSYS FLUENT. A very low weight fraction (0.0009%) of nanoparticles was considered due to the computational limitations of the software package. The temperature distribution and particle distribution results calculated by the 3D CFD model were one-way coupled with a 2D Cellular Automata (CA) model to predict the solidified microstructure using MATLAB. The coupled CFD-CA model and Lagrangian particle tracking were separately validated in this study. The result showed that the nanoparticles move along the recirculation zones generated by the Marangoni and natural convection in the molten pool fluid. The microstructure predicted by this model showed that the introduction of the nanoparticles increased bulk nucleation during solidification. It disrupted columnar grain growth by promoting small, randomly oriented equiaxed grains. The average grain diameter decreased by 40% when nanoparticles were present compared to microstructures without nanoparticles.
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Adams, Sarah M. y Regina Ragan. "Gold Nanoparticle Self Assembly on Diblock Copolymers for Application as Biomolecular Sensors". En ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13126.
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Current efforts in medical diagnostic technology focus toward developing biological sensors with the capacity for detecting trace quantities of specified organic molecules. In this study, metallic nanoparticles were investigated for the development of field-enhanced chemical and biological detection devices with the capacity to achieve single-molecule level detection resulting from surface enhanced Raman scattering (SERS) associated with closely spaced noble metal nanostructures.[1, 2] Localized surface plasmon resonance (LSPR) sensors likewise benefit from the incorporation of ordered metal nanoparticles on surfaces, providing increased shift in minimum of reflectivity with biological binding event (figure 1).[3]
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Zhang, Shaozhe, Andreas Rittsche, Ronny Künanz y Matthias H. Buschmann. "Experimental Investigation of Alternative Coolants for Combustion Engine Valves". En ASME 2024 7th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/mnhmt2024-130901.
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Abstract Valves of combustion engines are often hollow. Liquid metal oscillates in these cavities due to the movement of the valve, thereby cooling it. The aim of our experiments is to investigate if the addition of loose disruptive bodies such as spheres or the alteration of the thermophysical properties of the cooling medium by adding metallic nanoparticles improves the cooling performance. The expectation is that especially mobile spheres enhance the impingement of the liquid metal on the inner valve walls and therewith the local heat transfer. The study presents seventeen experiments employing a generic valve body made of AISI 316L. The working fluid is the eutectic gallium-indium-tin alloy. The experiments comprise five different combinations of disruptive bodies and one test with the gallium alloy modified with metallic nanoparticles. The results show that the equivalent thermal conductivity of the system is doubled when adding one single large sphere to the liquid alloy compared to the reference case. Adding three such disruptive bodies leads to a nearly quadruplication of the equivalent thermal conductivity.
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Venkata, Pradeep Garudadri, Mustafa M. Aslan, M. Pinar Mengu¨c y Gorden Videen. "The Surface Plasmon Scattering Patterns of Gold Nanoparticles and Agglomerates". En ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82927.
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Metallic nanoparticles display considerably different optical properties than those of their bulk counterparts. They have long been of interest in several novel applications, from colored glass production of medieval times to molecular-level sensors of today. Recently, there has been significant interest in characterization of such small particles via surface plasmons, for example for monitoring of the actual self-assembly purposes. For such characterization, we need scattering patterns by different type of particles and agglomerates on or near the surface. Here we present a methodology to predict the required scattering patterns of single particles and agglomerates on or near a surface subjected to surface plasmon waves. We investigate the effect of size, shape and orientation of gold nano particles on their scattering patterns both in the visible spectrum and at resonance wavelengths. The results show that the normalized scattering matrix elements (Mij) at certain observation angles and incident wavelengths provide significant information to monitor self-assembly process of gold nanoparticles on a gold substrate.