Добірка наукової літератури з теми "Particules nanostructurées"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Particules nanostructurées".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Статті в журналах з теми "Particules nanostructurées":
1
Maciulis, Vincentas, Almira Ramanaviciene, and Ieva Plikusiene. "Recent Advances in Synthesis and Application of Metal Oxide Nanostructures in Chemical Sensors and Biosensors." Nanomaterials 12, no. 24 (December 10, 2022): 4413. http://dx.doi.org/10.3390/nano12244413.
Анотація:
Nanostructured materials formed from metal oxides offer a number of advantages, such as large surface area, improved mechanical and other physical properties, as well as adjustable electronic properties that are important in the development and application of chemical sensors and biosensor design. Nanostructures are classified using the dimensions of the nanostructure itself and their components. In this review, various types of nanostructures classified as 0D, 1D, 2D, and 3D that were successfully applied in chemical sensors and biosensors, and formed from metal oxides using different synthesis methods, are discussed. In particular, significant attention is paid to detailed analysis and future prospects of the synthesis methods of metal oxide nanostructures and their integration in chemical sensors and biosensor design.
2
Salvat-Pujol, Francesc, Harald O. Jeschke, and Roser Valentí. "Simulation of electron transport during electron-beam-induced deposition of nanostructures." Beilstein Journal of Nanotechnology 4 (November 22, 2013): 781–92. http://dx.doi.org/10.3762/bjnano.4.89.
Анотація:
We present a numerical investigation of energy and charge distributions during electron-beam-induced growth of tungsten nanostructures on SiO2 substrates by using a Monte Carlo simulation of the electron transport. This study gives a quantitative insight into the deposition of energy and charge in the substrate and in the already existing metallic nanostructures in the presence of the electron beam. We analyze electron trajectories, inelastic mean free paths, and the distribution of backscattered electrons in different compositions and at different depths of the deposit. We find that, while in the early stages of the nanostructure growth a significant fraction of electron trajectories still interacts with the substrate, when the nanostructure becomes thicker the transport takes place almost exclusively in the nanostructure. In particular, a larger deposit density leads to enhanced electron backscattering. This work shows how mesoscopic radiation-transport techniques can contribute to a model that addresses the multi-scale nature of the electron-beam-induced deposition (EBID) process. Furthermore, similar simulations can help to understand the role that is played by backscattered electrons and emitted secondary electrons in the change of structural properties of nanostructured materials during post-growth electron-beam treatments.
3
Lee, Jinho, Donghwi Cho, Haomin Chen, Young-Seok Shim, Junyong Park, and Seokwoo Jeon. "Proximity-field nanopatterning for high-performance chemical and mechanical sensor applications based on 3D nanostructures." Applied Physics Reviews 9, no. 1 (March 2022): 011322. http://dx.doi.org/10.1063/5.0081197.
Анотація:
In this era of the Internet of Things, the development of innovative sensors has rapidly accelerated with that of nanotechnology to accommodate various demands for smart applications. The practical use of three-dimensional (3D) nanostructured materials breaks several limitations of conventional sensors, including the large surface-to-volume ratio, precisely tunable pore size and porosity, and efficient signal transduction of 3D geometries. This review provides an in-depth discussion on recent advances in chemical and mechanical sensors based on 3D nanostructures, which are rationally designed and manufactured by advanced 3D nanofabrication techniques that consider structural factors (e.g., porosity, periodicity, and connectivity). In particular, we focus on a proximity-field nanopatterning technique that specializes in the production of periodic porous 3D nanostructures that satisfy the structural properties universally required to improve the performance of various sensor systems. State-of-the-art demonstrations of high-performance sensor devices such as supersensitive gas sensors and wearable strain sensors realized through designed 3D nanostructures are summarized. Finally, challenges and outlooks related to nanostructures and nanofabrication for the practical application of 3D nanostructure-based sensor systems are proposed.
4
Wiederrecht, Gary P. "(Invited) Dynamics of Light-Matter Interactions in Plasmonic Optical Cavities for Characterizing Nanostructures Relevant to Energy Conversion and Photocatalysis." ECS Meeting Abstracts MA2023-01, no. 37 (August 28, 2023): 2168. http://dx.doi.org/10.1149/ma2023-01372168mtgabs.
Анотація:
Optical cavities are an established means to increase light-matter interactions with a wide range molecules, nanostructures and bulk materials. The use of an optical cavity to increase the likelihood of photon absorption by a material has clear potential for being of value for optical energy conversion and photocatalysis. Furthermore, optical cavities can significantly alter excited state dynamics due to the potential for Purcell effects that increase radiative rates of emission of a given material, molecule, or nanostructure. These dynamic changes can serve as a sensing mechanism of cavity impact to photoprocesses, making characterization tools such as transient absorption and time-resolved emission measurements an effective means to probe the degree of light-matter coupling. Taken a step further, these characterization tools can help establish the degree of light-matter coupling necessary to control excited state lifetimes for a particular purpose or application. Here, we explore the dynamics of nanostructured systems coupled to, or made out of, plasmonic materials. Importantly, plasmonic structures are well-known to serve as a type of optical cavity, and though plasmonic cavities are lossier than their dielectric counterparts, they can also confine light to a small mode volume which is very helpful for increasing photonic interactions with nanostructures. The focus of this talk is on materials and nanostructures of interest for solar energy conversion or photocatalysis, such plasmonic nanoparticles and semiconducting nanoparticles, which are interacting with or functioning as, a plasmonic cavity. The plasmonic cavity can be as simple as a thin metal film that supports a propagating surface plasmon polariton (SPP). We also explore refractory plasmonic systems due to their potential durability and reduced likelihood of melting under optical illumination as compared to noble metal nanostructures. The dynamics of nanostructure photoprocesses as a function of photon energy relative to the cavity resonance is explored in detail and impact on applications is described. Work performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
5
Candemir, Duygu, and Filiz Boran. "Size Controllable Synthesis and Characterization of CuO Nanostructure." Materials Science Forum 915 (March 2018): 98–103. http://dx.doi.org/10.4028/www.scientific.net/msf.915.98.
Анотація:
In this study, copper oxide (CuO) nanostructures were successfully prepared by adding EG (ethylene glycol) and PEG (4000, 8000) (polyethylene glycol) via an in-situ chemical precipitation method. EG and PEG (4000, 8000) were effective for changing the particular size of CuO and we examined the effects of drying type such as freeze drying, muffle and horizontal furnace on the size of CuO nanostructure. The structure, morphology and elemental analysis of CuO nanostructure were analyzed by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). Also, the CuO nanostructures showed excellent electrical conductivity by the changing of PEG’s molecular weight and drying processes.
6
Chen, Yulin, Ping Ma, and Shuangying Gui. "Cubic and Hexagonal Liquid Crystals as Drug Delivery Systems." BioMed Research International 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/815981.
Анотація:
Lipids have been widely used as main constituents in various drug delivery systems, such as liposomes, solid lipid nanoparticles, nanostructured lipid carriers, and lipid-based lyotropic liquid crystals. Among them, lipid-based lyotropic liquid crystals have highly ordered, thermodynamically stable internal nanostructure, thereby offering the potential as a sustained drug release matrix. The intricate nanostructures of the cubic phase and hexagonal phase have been shown to provide diffusion controlled release of active pharmaceutical ingredients with a wide range of molecular weights and polarities. In addition, the biodegradable and biocompatible nature of lipids demonstrates the minimum toxicity and thus they are used for various routes of administration. Therefore, the research on lipid-based lyotropic liquid crystalline phases has attracted a lot of attention in recent years. This review will provide an overview of the lipids used to prepare cubic phase and hexagonal phase at physiological temperature, as well as the influencing factors on the phase transition of liquid crystals. In particular, the most current research progresses on cubic and hexagonal phases as drug delivery systems will be discussed.
7
Lee, Seunggi, Jae Han Chung, Yun Haeng Cho, Donghwi Cho, and Young-Seok Shim. "Research Trends in One-dimensional Nanostructures based Gas Sensors fabricated by Glancing Angle Deposition." Ceramist 26, no. 3 (September 30, 2023): 290–302. http://dx.doi.org/10.31613/ceramist.2023.26.3.06.
Анотація:
One-dimensional (1D) nanostructures allow for precise control of geometrical size and shape, offering greater design flexibility than other nanostructures. 1D nanostructures, in particular, hold immense potential for revolutionizing the gas sensor field, owing to their extensive surface areas conducive to chemical reactions. To harness this potential, researchers have dedicated their efforts to developing fabrication methods that incorporate 1D nanostructures into gas sensor applications. Various techniques have been explored, including hydrothermal synthesis, electrospinning, sol-gel processes, solid-state chemical reactions, vapor-phase transport, and chemical vapor deposition. Despite these advancements, challenges regarding uniformity and reproducibility persist. In this report, we review the glancing angle deposition (GLAD) technique for applying 1D nanostructures to gas sensors and discuss to the potential of GLAD in overcoming existing limitations and driving forward the realm of 1D nanostructure-based gas sensors.
8
Adamek, Michał, Oleksandr Pastukh, Magdalena Laskowska, Agnieszka Karczmarska, and Łukasz Laskowski. "Nanostructures as the Substrate for Single-Molecule Magnet Deposition." International Journal of Molecular Sciences 25, no. 1 (December 19, 2023): 52. http://dx.doi.org/10.3390/ijms25010052.
Анотація:
Anchoringsingle-molecule magnets (SMMs) on the surface of nanostructures is gaining particular interest in the field of molecular magnetism. The accurate organization of SMMs on low-dimensional substrates enables controlled interactions and the possibility of individual molecules’ manipulation, paving the route for a broad range of nanotechnological applications. In this comprehensive review article, the most studied types of SMMs are presented, and the quantum-mechanical origin of their magnetic behavior is described. The nanostructured matrices were grouped and characterized to outline to the reader their relevance for subsequent compounding with SMMs. Particular attention was paid to the fact that this process must be carried out in such a way as to preserve the initial functionality and properties of the molecules. Therefore, the work also includes a discussion of issues concerning both the methods of synthesis of the systems in question as well as advanced measurement techniques of the resulting complexes. A great deal of attention was also focused on the issue of surface–molecule interaction, which can affect the magnetic properties of SMMs, causing molecular crystal field distortion or magnetic anisotropy modification, which affects quantum tunneling or magnetic hysteresis, respectively. In our opinion, the analysis of the literature carried out in this way will greatly help the reader to design SMM-nanostructure systems.
9
Culhane, Kyle, Ke Jiang, Aaron Neumann, and Anatoliy O. Pinchuk. "Laser-Fabricated Plasmonic Nanostructures for Surface-Enhanced Raman Spectroscopy of Bacteria Quorum Sensing Molecules." MRS Advances 2, no. 42 (2017): 2287–94. http://dx.doi.org/10.1557/adv.2017.98.
Анотація:
ABSTRACTA laser deposition technique, based on the photo-reduction of silver ions from an aqueous solution, was used to fabricate silver nanostructure surfaces on glass cover slips. The resulting silver nanostructures exhibited plasmonic properties, which show promise in applications towards surface enhanced Raman spectroscopy (SERS). Using the standard thiophenol, the enhancement factor calculated for the deposits was approximately ∼106, which is comparable to other SERS-active plasmonic nanostructures fabricated through more complex techniques, such as electron beam lithography. The silver nanostructures were then employed in the enhancement of Raman signals from N-butyryl-L-homoserine lactone, a signaling molecule relevant to bacteria quorum sensing. In particular, the work presented herein shows that the laser-deposited plasmonic nanostructures are promising candidates for monitoring concentrations of signaling molecules within biofilms containing quorum sensing bacteria.
10
Hasan, Mohammad Nasim, Sheikh Mohammad Shavik, Kazi Fazle Rabbi, Khaled Mosharraf Mukut, and Md Muntasir Alam. "Thermal transport during thin-film argon evaporation over nanostructured platinum surface: A molecular dynamics study." Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanomaterials, Nanoengineering and Nanosystems 232, no. 2-3 (June 2018): 83–91. http://dx.doi.org/10.1177/2397791418802498.
Анотація:
Investigation of thermal transport characteristics of thin-film liquid evaporation over nanostructured surface has been conducted using molecular dynamics simulation with particular importance on the effects of the nanostructure configuration for different wall–fluid interaction strengths. The nanostructured surface considered herein comprises wall-through rectangular nanoposts placed over a flat wall. Both the substrate and the nanostructure are of platinum while argon is used as the evaporating liquid. Two different wall–fluid interaction strengths have been considered that essentially emulate both hydrophilic and hydrophobic wetting conditions for three different nanostructure configurations. The argon–platinum molecular system is first equilibrated at 90 K and then followed by a sudden increase in the wall temperature at 130 K that induces evaporation of argon laid over it. Comparative effectiveness of heat and mass transfer for different surface wetting conditions has been studied by calculating the wall heat flux and evaporative mass flux. The results obtained in this study show that heat transfer occurs more easily in cases of nanostructured surfaces than in case of flat surface. Difference in behavior of argon molecules during and after the evaporation process, that is, wall adsorption characteristics, has been found to depend on the surface wetting condition as well as on presence and configuration of nanostructure. A thermodynamic approach of energy balance shows reasonable agreement with the present molecular dynamics study.
Дисертації з теми "Particules nanostructurées":
1
Desmoulins-Krawiec, Sophie. "Elaboration de particules nanostructurées de nitrures et d'oxynitrures métalliques en milieu fluide supercritique. Etude et modélisation des mécanismes de croissance des particules." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2004. http://tel.archives-ouvertes.fr/tel-00007176.
Анотація:
Les fluides supercritiques, au regard de leurs propriétés macroscopiques et microscopiques facilement modulables pour de faibles variations de pression et de température au voisinage de leur point critique, représentent une alternative intéressante pour la synthèse de nanomatériaux. Dans ce travail de thèse, nous avons réalisé une recherche exploratoire sur la décomposition thermique de précurseurs métalliques permettant la synthèse “contrôlée” de nanoparticules de nitrures métalliques en milieu fluide supercritique. Cette décomposition en conditions supercritiques permet d'alimenter le milieu réactionnel en atomes métalliques qui réagissent avec l'ammoniac supercritique pour former des particules nanostructurées de nitrures. L'objectif est de coupler au sein d'un même matériau, les propriétés intrinsèques des nitrures aux propriétés induites lorsqu'ils sont élaborés sous forme de nanomatériaux. Nous avons étudié dans un premier temps, l'effet des paramètres expérimentaux sur la composition chimique et la morphologie des matériaux afin de définir les potentialités du procédé. Nous avons montré que le facteur limitant de cette voie de synthèse est la présence d'oxygène dans le milieu qui conduit à la formation d'oxynitrures. Ensuite, nous avons focalisé nos recherches sur la synthèse du nitrure de nickel, Ni3N. L'analyse chimique et structurale du produit synthétisé a révélé la présence d'oxygène dans le matériau. Cependant, nous avons montré l'effet des conditions opératoires sur la morphologie du matériau élaboré en milieu ammoniac supercritique. En outre, une étude préliminaire des propriétés magnétiques des poudres synthétisées a été effectuée. Enfin, un modèle numérique permettant la prévision de l'évolution de la taille d'agrégats sphériques nanostructurés en fonction des paramètres expérimentaux (temps de séjour, concentration, température, ...) a été développé.
2
Desmoulins-Krawiec, Sophie. "Elaboration de particules nanostructurées de nitrures et d'oxynitrures métalliques en milieu fluide supercritique : étude et modélisation des mécanismes de croissance des particules." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12815.
Анотація:
Les fluides supercritiques, au regard de leurs propriétés macroscopiques et microscopiques facilement modulables pour de faibles variations de pression et de température au voisinage de leur point critique, représentent une alternative intéressante pour la synthèse de nanomatériaux. Dans ce travail de thèse, nous avons réalisé une recherche exploratoire sur la décomposition thermique de précurseurs métalliques permettant la synthèse contrôléeʺ de nanoparticules de nitrures métalliques en milieu fluide supercritique. Cette décomposition en conditions supercritiques permet d'alimenter le milieu réactionnel en atomes métalliques qui réagissent avec l'ammoniac supercritique pour former des particules nanostructurées de nitrures. L'objectif est de coupler au sein d'un même matériau, les propriétés intrinsèques des nitrures aux propriétés induites lorsqu'ils sont élaborés sous forme de nanomatériaux. Nous avons étudié dans un premier temps, l'effet des paramètres expérimentaux sur la composition chimique et la morphologie des matériaux afin de définir les potentialités du procédé. Nous avons montré que le facteur limitant de cette voie de synthèse est la présence d'oxygène dans le milieu qui conduit à la formation d'oxynitrures. Ensuite, nous avons focalisé nos recherches sur la synthèse du nitrure de nickel, Ni3N. L'analyse chimique et structurale du produit synthétisé a révélé la présence d'oxygène dans le matériau. Cependant, nous avons montré l'effet des conditions opératoires sur la morphologie du matériau élaboré en milieu ammoniac supercritique. En outre, une étude préliminaire des propriétés magnétiques des poudres synthétisées a été effectuée. Enfin, un modèle numérique permettant la prévision de l'évolution de la taille d'agrégats sphériques nanostructurés en fonction des paramètres expérimentaux (temps de séjour, concentration, température, ) a été développéMacroscopic and microscopic supercritical fluids properties can be easily tuned by weak variations of pressure and temperature near their critical point. So they represent an interesting alternative for nanomaterials synthesis. In this study we achieved an explorative research about thermal decomposition of metal precursors to allow a controlled synthesis of metal nitride nanoparticles in supercritical fluid. This decomposition, in supercritical conditions, permits to feed reactive media with metal atoms that react with supercritical ammonia to form nitride nanostructured particles. The aim is to couple within the material, intrinsic properties of nitrides with properties linked to nanoscopic scale. Firstly, we studied experimental parameters effect on material chemical composition and on material morphology in order to define the process potentialities. We showed that the limiting factor for this process is the oxygen presence in the experimental set-up which induces the formation of oxinitride. Next, we focus our researches on nickel nitride, Ni3N. Chemical and structural analysis revealed an insertion of oxygen atoms in the Ni3N structure. Nevertheless, we showed experimental conditions effect on morphology of synthesized material in supercritical ammonia. In addition, a preliminary study on magnetic properties of powders was performed. Finally, a numeric model to predict spherical nanostructured aggregates size evolution versus experimental parameters (residence time, precursor concentration, temperature ) was developed
3
Nuvoli, Jonathan. "Étude des mécanismes de formation des dépôts de particules appliquée à la filtration THE." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0049.
Анотація:
La filtration de l’air par des médias fibreux à très haute efficacité (THE) constitue un élément important pour la sécurité des installations sensibles. Pourtant, les filtres présentent un inconvénient majeur lié à l’augmentation de leur résistance aéraulique au cours de leur colmatage ce qui peut conduire in fine au déséquilibrage du réseau de ventilation, voire dans des cas extrêmes à la rupture du filtre et par conséquent à une perte de confinement. Dans certaines situations accidentelles, telles qu’un incendie, les filtres peuvent être soumis à un apport important de particules ou à des particules très colmatantes, occasionnant une élévation rapide de leur perte de charge. Dans les modèles de perte de charge existants utilisés pour l’évaluation des risques, la porosité est une donnée d’entrée clef. De nombreux auteurs, via des simulations, ont proposé des valeurs de porosité pour des dépôts de nanoparticules formés par filtration et ont montré, pour un aérosol donné, une dépendance de la porosité en fonction du nombre de Péclet (rapport des mécanismes de transport par convection et diffusion). Une méthodologie expérimentale spécifique a été développé afin d’étudier notamment l’influence, sur la porosité des dépôts, de la taille et la morphologie des particules, des caractéristiques physico-chimiques des particules et du gaz vecteur (nature, masse volumique, viscosité) et des conditions opératoires (vitesse de filtration, pression). Pour cette étude, un banc expérimental ainsi qu’un dispositif de mesure laser spécifiques ont été développés. Ce dernier mesure l’évolution de l’épaisseur du dépôt couplée à sa masse déposée au cours du temps afin de déterminer sa porosité. Les études sur les dépôts de nanoparticules sphériques et formées par des agrégats ont permis de définir le nombre de Stokes (rapport entre l’énergie cinétique de la particule et l’énergie dissipée par frottement avec le fluide) comme le paramètre le plus pertinent pour rendre compte de l’évolution de la porosité du dépôt. Cette étude a débouché sur différentes corrélations permettant l’estimation de la porosité d’un dépôt de nanoparticules pseudo-sphériques ou de particules nanostructuréesThe filtration of air by fibrous media with high efficiency particulate air (HEPA) is a key point for the safety of sensitive installations. However, filters have a major drawback linked to the increase in their aeraulic resistance during their clogging, which can lead to unbalance the ventilation networks, or even in extreme cases to the rupture of filters and therefore to a loss of containment. In case of fire the filters may be subjected to a large supply of particles or to very clogging particles, causing a rapid increase in their pressure drop. In current pressure drop models used for risk assessment, porosity is a key parameter. Many authors, via simulations, have proposed porosity values for deposits of nanoparticles formed by filtration and have shown, for a given aerosol, a dependence of the porosity as a function of the Peclet number (ratio of the transport mechanisms by convection and diffusion. A specific experimental methodology has been developed in order to study the influence of the porosity of the deposits of the size and morphology of the particles, the physico-chemical characteristics of the particles and the carrier gas (nature, density, viscosity) and operating conditions (filtration rate, pressure). For this study, an experimental bench and a laser measurement device have been developed. This device measures the change in the thickness of the deposit coupled with its deposited mass over time in order to determine the porosity of the deposit. Studies on the deposits of spherical nanoparticles and formed by aggregates have made it possible to define the Stokes number (ratio between the kinetic energy of the particle and the energy dissipated by friction with the fluid) as the most relevant parameter to account for the evolution of the porosity of the deposit. This study led to various correlations allowing the estimation of the porosity of a deposit of pseudo-spherical nanoparticles or nanostructured particles
4
Chézeau, Laëtitia. "Étude au niveau pulmonaire du profil d’expression de gènes et de protéines chez le rat exposé par inhalation à un aérosol de particules nanostructurées de dioxyde de titane." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0226/document.
Анотація:
En raison de l'utilisation croissante de nanomatériaux dans divers procédés industriels, le nombre de salariés potentiellement exposés ne cesse d’augmenter, sans que pour autant les propriétés toxicologiques de ces agents chimiques ne soient parfaitement connues. Comme des nanoparticules (NP) peuvent être mises en suspension dans les environnements de travail, l'inhalation représente la principale voie d'exposition professionnelle. Ainsi, l’évaluation des dangers associés à l’exposition à des aérosols nanostructurés nécessite de réaliser des études de toxicologie expérimentale par inhalation, en utilisant des modèles animaux. Dans ce travail, les propriétés toxicologiques pulmonaires d’un aérosol nanostructuré de dioxyde de titane (TiO2) ont été étudiées à court et long termes, en combinant des analyses toxicologiques conventionnelles (analyses du lavage broncho-alvéolaire (LBA), histopathologie des poumons et des ganglions lymphatiques); et de criblage moléculaire à haut contenu (analyses de transcriptomique et de protéomique). Des rats Fischer 344 ont été exposés par inhalation oro-nasale, à un aérosol nanostructuré de TiO2 à 10 mg / m3 ; 6 heures par jour, 5 jours par semaine pendant 4 semaines. Des échantillons biologiques ont été prélevés immédiatement et jusqu'à 180 jours suivant la fin de l'exposition. L'exposition à l'aérsosol nanostructuré de TiO2 a entraîné une importante réponse inflammatoire pulmonaire aiguë. Cette réponse était caractérisée par un influx de granulocytes neutrophiles, la présence de macrophages chargés en particules au niveau alvéolaire, la surexpression de gènes et de protéines impliqués dans les réponses inflammatoires et immunitaires, les cascades du complément et de la coagulation, le stress oxydant. Certains gènes surexprimés étaient également impliqués dans les lésions de l'ADN et la fibrose; et certaines protéines surexprimées étaient associées au protéasome et à l'organisation du cytosquelette. Dans le surnageant du LBA, l’augmentation du niveau d'histones et d'autres protéines associées aux pièges extracellulaires des neutrophiles (Neutrophilic Extracellular Trap, NET) suggère la libération de ces pièges extracellulaires dans l'espace alvéolaire. Cette libération possible de NET se produit dans un contexte inflammatoire mais en l'absence de changements histopathologiques significatifs. Ce processus inattendu n’a fait l’objet que de très peu d’études en lien avec une exposition à des nanomatériaux. Six mois après la fin de l'exposition (réponse à long terme), l'inflammation a diminué et s’accompagnait d’une baisse de la charge pulmonaire de titane (un marqueur fiable de la charge pulmonaire en nanoparticules de TiO2), mais de nombreux gènes et protéines étaient différentiellemment exprimés. Les conséquences physiopathologiques des changements rapportés ici ne sont pas entièrement connues, mais ces résultats devraient susciter des interrogations quant aux effets pulmonaires à long terme des NP inhalées biopersistantes de faible toxicité comme le TiO2. En conclusion, ce travail montre qu'il existe une bonne relation entre les changements cytologiques et histopathologiques d'une part et les modifications des profils d'expression de gènes et de protéines d'autre part. Cependant, dans certains cas, la transcriptomique et la protéomique pourraient être plus sensibles que les méthodes conventionnelles pour identifier de nouvelles propriétés toxicologiques, ou pour mieux comprendre les mécanismes moléculaires sous-jacents de la toxicité des produits chimiques. Notre étude avec d'autres travaux de la littérature pourraient également être utiles pour identifier des biomarqueurs d’exposition aux nanomatériaux ou prédire leurs effets nocifs à long termeDue to the growing use of nanomaterials in various industrial processes, the number of workers potentially exposed is increasing even though the toxicological properties of these compounds are not completely known. Since nanoparticles (NP) may get aerosolized, inhalation represents their main route of occupational exposure. Then, inhalation studies of nanomaterial toxicity in animal models appear to be the most relevant approach to assess their hazards. In this work, we studied the short and long term pulmonary toxicological properties of inhaled titanium dioxide (TiO2) nanostructured aerosol (NSA), using conventional (broncho-alveolar lavage (BAL) analyses, lung and lymph nodes histopathology); and high content molecular toxicological approaches (transcriptomics and proteomics analyses). Fischer 344 rats were exposed to 10 mg/m3 of TiO2 nanostructured aerosol by nose-only inhalation, 6h/day, 5 days/week for 4 weeks. Biological samples were collected immediately and up to 180 post-exposure days. Exposure to TiO2 NSA resulted in a strong acute pulmonary inflammation. This response was characterized by a neutrophil influx, the presence of particle-laden macrophages in the alveolar lumen, as well as overexpression of genes and proteins involved in inflammatory and immune responses, complement and coagulation cascades, oxidative stress. Some overexpressed genes were also involved in DNA damage and fibrosis; and some overexpressed proteins in proteasome and cytoskeleton organization. In the BAL supernatant, the increased level of histones and other neutrophilic extracellular trap (NET) -associated proteins suggests the release of these traps in the alveolar space. This possible NET release occurs in an inflammatory context but in the absence of significant histopathological changes. Very few studies reported this unexpected process related to exposure to nanomaterials. Six months after the end of exposure (long-term response), inflammation had decreased in line with the decrease of titanium lung burden (a surrogate for TiO2 pulmonary deposition), but many genes and proteins remained differentially expressed. The physiopathological consequences of the molecular changes reported here are not fully known, but these results should raise concern about the long-term pulmonary effects of inhaled low toxicity NP such as TiO2. Altogether, this work shows that there is a good relationship between cytological and histopathological changes in one hand and gene as well as protein expression profile modifications in the other hand. However, in some cases transcriptomics or proteomics could be more sensitive than conventional methods to identify new toxicological properties or to better understand the underlying molecular mechanisms of chemicals toxicity. Our study along with others could also be helpful to identify biomarkers of exposure or predict the long-term adverse effects of nanomaterials
5
Iskandar, Abdo. "Phonon Heat Transport and Photon-phonon Interaction in Nanostructures." Thesis, Troyes, 2018. http://www.theses.fr/2018TROY0010.
Анотація:
Cette thèse avait pour cadre, le contrôle du transport thermique via les phonons et leur interaction avec des photons dans des nanostructures. Le manuscrit comprend cinq chapitres. Dans le premier, nous introduisons la physique des phonons et excitations élémentaires optiques de la matière. Le deuxième chapitre fournit une description des procédés de croissance, techniques de structuration et techniques de caractérisation utilisées. Dans le troisième chapitre, nous démontrons qu’à la fois, phonons et photons peuvent être confinés et interagir dans une même nanostructure. Dans le quatrième chapitre, nous montrons expérimentalement que le spectre de phonons d'un matériau peut être modifié par des mécanismes d'hybridation entre des modes de surface introduits par une nanostructuration et les modes normaux du matériau massif. Nous montrons que la forme et la taille des nanostructures sur la surface du matériau ont des effets sur le spectre de phonons du substrat. Dans le cinquième chapitre, nous montrons qu'à basse température (inférieure à 4 K), la chaleur spécifique des nanofils est équivalente à celle d'un cristal essentiellement bidimensionnel. Encore plus étonnant à l'interface entre les nanofils et le substrat, nous avons mis en évidence une transition entre une transmission élastique spéculaire et une transmission élastique diffuse. Lorsque la température augmente on observe alors une transition entre une diffusion élastique et une diffusion inélastique. L’ensemble de ces résultats laisse entrevoir des perspectives intéressantes pour le contrôle des propriétés thermiques de matériaux massifs par nanostructuration de surfaceIn this dissertation, we investigate phonon heat transport and phonon interaction with optical elementary excitations in nanostructures. In the first chapter, we present an introduction to the physics of phonons and optical elementary excitations in nanostructured materials. The second chapter provides a detailed description of the samples growth and fabrication procedures and the various characterization techniques used. In the third chapter, we demonstrate that phonons and photons of different momenta can be confined and interact with each other within the same nanostructure. In the fourth chapter, we present experimental evidence on the change of the phonon spectrum and vibrational properties of a bulk material through phonon hybridization mechanisms. We demonstrate that the phonon spectrum of a bulk material can be altered by hybridization between confined phonon modes in nanostructures introduced on the surface of the material and the underlying bulk phonon modes. Shape and size of the nanostructures made on the surface of the substrate have strong effects on the phonon spectrum of the bulk material itself. In the fifth chapter, we demonstrate that at low temperatures (below 4 K) the nanowire specific heat exhibits a clear contribution from an essentially two-dimensional crystal. We also demonstrate that transitions from specular to diffusive elastic transmission and then from diffusive elastic to diffusive inelastic transmission occur at the interface between nanowires and a bulk substrate as temperature increases. Perspectives include the control of bulk material thermal properties via surface nanostructuring
6
Ly, Aboubakry. "Effet Seebeck à l’échelle nanométrique de nanostructures chaudes." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0010/document.
Анотація:
L'objectif de ce travail est d'étudier l'effet thermoélectrique à l'échelle nanométrique des nanostructures chauffées. Dans un premier temps, nous étudions les mécanismes d'autopropulsion thermo-électrophorétique de particules Janus chauffées par laser. Ce mécanisme d'autopropulsion est principalement induit par l'effet Seebeck ou l'effet thermoélectrique. Cet effet provient de la séparation des charges survenues lorsqu'un gradient de température est présent dans la solution d'électrolyte: Une forte absorption du laser par la partie métallisée de la particule génère un gradient de température qui en retour agit sur les espèces ioniques (positive et négative) et les conduits vers les zones chaudes ou les zones froides. Ce mouvement d'ions entraine la création d'un champ électrique dipolaire qui, à proximité de la particule, dépend fortement des propriétés de surface. Ce changement de comportement de ce champ électrique sur une surface isolant ou conductrice n'affecte pas la vitesse de la particule. Dans un second temps, nous étudions les effets d'interactions hydrodynamiques et de la condensation des contre-ions sur la thermophorèse des polymères d'ADN. Comme résultat principal, la mobilité thermophorétique montre, en fonction de la longueur de la chaîne, un comportement non-monotone et se compose de deux contributions induites par les forces conductrices dominantes que sont l'effet Seebeck et le gradient de permittivité. À la fin, nous comparons notre résultat théorique avec une récente expérience sur l'ADNThe aim of this work is to study the nanoscale Seebeck effect at hot nanostructures. At first, we study the thermo-electrophoresis self-propulsion mechanism for a heated metal capped Janus colloid. The self-propulsion mechanism is mainly induced by the electrolyte Seebeck effect or thermoelectric effect. This effect takes its origin from the separation of charges occurring while a temperature gradient is present in a electrolyte solution: A strong absorption of laser light by the metal side of the particle creates a temperature gradient which in turn acts on ion-species (positive and negative) and drives them to the hot or the cold region. This motion of ion results in a dipolar electric field which, close to the particle, depends strongly on the surface properties. The change of behavior of the electric field at the insulating or conducting surface does not affect the velocity of the particle. At second, we study the effect of hydrodynamic interactions and counterion condensation in thermophoresis for DNA polymer. As the main result, the thermophoretic mobility shows, in function of the chain length, a non-monotonuous behavior and consists of two contributions induced by the dominant driving forces which are the thermally induced permittivity-gradient and the electrolyte Seebeck effect. At the end, we compare our theoretical result with recent experiment on single-stranded DNA
7
Dems, Dounia. "Nanostructuration de particules de silice et élaboration de biomatériaux composites." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS373.
Анотація:
Ce travail décrit l’élaboration de biomatériaux modulables pour l’ingénierie tissulaire. L’approche composite utilisée procure de nombreux avantages pour améliorer l’adhésion cellulaire et contrôler la bioactivité en jouant sur des paramètres structuraux et fonctionnels. La matrice du composite est composée d’une macromolécule, le collagène, ou d’auto-assemblages supramoléculaires synthétiques (peptides amphiphiles). Des nanoparticules de silice fonctionnalisées y sont incorporées et jouent le rôle de plateformes capables de modifier les paramètres structuraux de la matrice et/ou d’apporter des signaux biochimiques pour créer le meilleur environnement pour les cellules. La combinaison de peptides amphiphiles et de ces nanoparticules permet de présenter un ou deux épitopes de façon homogène ou sous forme de clusters. Elle a permis de démontrer que l’organisation des signaux chimiques est essentielle à la bioactivité du matériau. Dans un deuxième temps, afin de contrôler l’organisation spatiale des ligands à la surface des nanoparticules, nous avons établi une stratégie originale utilisant des précurseurs alkoxysilanes qui s’auto-assemblent pour former des domaines transférables à la surface de la particule pour former des patches. Une bibliothèque de particules mono ou bi-fonctionnalisées a été synthétisée et incorporée dans des fils de collagène dont la modularité a été utilisée dans un modèle de régénération nerveuse périphérique. Enfin, nous avons développé un protocole pour l’électrofilage du collagène respectant son intégrité structurale afin de créer des membranes 3D fines et poreuses qui offriraient un meilleur accès des cellules aux particulesThis work describes the design of tunable biomaterials for tissue engineering. The composite approach provides numerous advantages to enhance cell adhesion and control bioactivity by complying both with structural and functional requirements. The host matrix, made from a natural macromolecule (collagen), or from synthetic supramolecular polymers (peptide amphiphiles), provides a suitable structural environment to the cells and can also display intrinsic biochemical cues to influence cell behavior. Functionalized silica nanoparticles can be added to be used as platforms either to further tune the architecture of the scaffold or display additional bioactive ligands. The combination of peptide amphiphiles with such nanoparticles led to composite biomaterials with high modularity allowing to compare different displays of one bioactive epitope and the simultaneous grafting of two epitopes known to work in a distance-dependent manner. The next step was to achieve the control of the spatial organization of several functions on the surface of a single nanoparticle. We have developed an original and challenging strategy based on the synthesis of self-assembling alkoxysilane precursors that could form pre-organized domains to be transferred at the silica nanoparticle surface to create patches. A large library of mono- and bifunctional particles were prepared that were incorporated in collagen-based threads evaluated in a model of peripheral nerve regeneration. Finally, we have elaborated thin porous scaffolds by electrospinning collagen in non-denaturing conditions that should allow to improve the cells access to the functional nanoparticles
8
Jasiak, Rafal. "Ultrafast electron dynamics and decoherence in metallic nanostructures." Strasbourg, 2011. http://www.theses.fr/2011STRA6040.
Анотація:
La dynamique électronique ultrarapide dans des films métalliques minces a été étudiée numériquement en utilisant à la fois un modèle semi-classique (de Vlasov-Poisson) et un modèle quantique basé sur l'équation de Wigner. Pour de grandes énergies d'excitation, la dynamique quantique et la dynamique classique sont pratiquement identiques. En revanche, pour des plus basses énergies les cas classique et quantique divergent à partir d'un certain seuil, qui est de l’ordre de l'énergie du plasmon. Cet effet marque une transition classique – quantique, qui pourrait être observée dans les expériences de type pompe-sonde sur des films métalliques minces. A des échelles de temps plus longues, les électrons interagissent de façon incohérente avec les ions du réseau. Un temps de relaxation classique et un temps de décohérence quantique ont été mis en évidence à l’issue des résultats des simulations. Ces échelles de temps sont en bon accord avec les estimations phénoménologiques basées sur le modèle à deux températures, et reproduisent correctement les principales caractéristiques observées lors d'expériences sur des petits agrégats de sodiumThe ultrafast electron dynamics in thin metal films was studied numerically using both a semiclassical model (Vlasov-Poisson) and a fully quantum approach based on the Wigner equation. For large excitation energies, the quantum and classical dynamics are virtually identical, whereas they diverge below a certain threshold, roughly equal to the plasmon energy. This is a clear signature of a quantum-mechanical effect, which should be observable in standard pump-probe experiments on thin metal films. For longer timescales, the electron dynamics becomes dissipative, as the electrons exchange energy incoherently with the ion lattice. A classical relaxation time and a quantum decoherence time were shown to emerge naturally from the simulations. These time scales are in good agreement with phenomenological estimates based on the two-temperature model, and correctly reproduce the main features observed in experiments on small sodium clusters
9
Chenal, Marion. "Particules cœur-écorce par polymérisation raft en émulsion pour des matériaux nanostructurés sans solvants." Paris 6, 2013. http://www.theses.fr/2013PA066303.
Анотація:
Le but de ce projet était d’améliorer les propriétés mécaniques des films de latex, qui constituent une alternative intéressante aux traditionnelles formulations à base de solvants organiques afin de répondre aux nouvelles normes environnementales et sanitaires (réduction des émissions de COV). Une stratégie basée sur l’emploi de particules cœur-écorce a été choisie. La polymérisation de l’acrylate de butyle (ABu) a été réalisée en émulsion en conditions batch ab initio sans tensioactifs, à partir d’un macroagent RAFT poly(acide acrylique)-trithiocarbonate (PAA-TTC) qui joue le rôle d’agent de contrôle et de stabilisant. Des copolymères PAA-b-PABu de masses molaires élevées ont pu être obtenus avec un bon contrôle, sans coagulum. Ces copolymères à blocs s’auto-organisent lors de la polymérisation en particules cœur-écorce comportant un cœur mou PABu et une écorce rigide PAA très fine (~ 1 nm). Après évaporation de la phase aqueuse, des films homogènes et transparents ont été obtenus. Les films demeurent transparents après immersion dans l’eau, grâce à l’absence de tensioactifs dans la formulation. Les analyses de SAXS et de microscopie ont montré que les films étaient nanostructurés, du fait de la formation d’un réseau percolant rigide à partir des écorces PAA. D’après les analyses mécaniques (petites et grandes déformations), les films sont rigides et extensibles. Le procédé est versatile : grâce à la polymérisation radicalaire contrôlée, les masses des blocs peuvent être modifiées pour obtenir un film plus ou moins rigide et/ou extensible. De plus, le cœur ou l’écorce des particules peuvent être réticulés pour moduler les propriétés mécaniques des filmsThe aim of this project was to improve the mechanical properties of latex-based films, which represent an attractive alternative to solvent-based formulations in order to reduce volatile organic compounds emissions and move towards green chemistry. A strategy based on core-shell particles was chosen. Aqueous emulsion polymerization of n-butyl acrylate was performed in batch conditions without surfactants using a poly(acrylic acid)-trithiocarbonate macroRAFT agent to control the polymerization and stabilize the emulsion. The resulting well-defined amphiphilic PAA-b-PBA diblock copolymers self-assemble during synthesis to yield highly stable core-shell particles with an extremely thin PAA shell. After drying the aqueous dispersion, tough and transparent films were obtained. As they do not contain surfactants, the films remain transparent even after immersion in water. Rheology showed that the films are both stiff and ductile, thanks to the nanostructured but very low volume fraction (less than 3 wt%) of PAA in the soft PBA. Microscopy and SAXS experiments proved that the PAA shells form a percolating network throughout the film, which is responsible for the enhanced mechanical properties. Compared to conventional core-shell based films, this approach affords for the first time a route to a thin percolating honeycomb nanostructure with both a sharp and a strong interface between the two phases. The versatility of the synthetic procedure opens perspectives for a large range of functional materials. For example, the molar mass of the PAA or the PBA block can be varied, or cross-linking can be introduced in the core and/or the shell of the particles
10
Benghorieb, Soulef. "Modélisation des modifications des propriétés optiques de nouveaux matériaux nanostructurés par des particules métalliques." Thesis, Saint-Etienne, 2011. http://www.theses.fr/2011STET4002.
Анотація:
Ce travail de thèse porte sur la modélisation des propriétés optiques de diélectriques nanostructurés par des particules métalliques. Nous nous sommes intéressés à deux aspects du problème : la détermination de l’indice effectif et la distribution du champ du plasmon de nanoparticules métalliques dispersées dans de tels milieux. Nous avons développé deux approches numériques. La première étude a été consacrée à la modélisation des parties réelle et imaginaire de l’indice effectif d’un milieu hétérogène. Pour comparer nos résultats de simulations d’indice à l’expérience, nous avons proposé une méthode expérimentale pour la mesure de l'indice de réfraction effectif de solutions colloïdales comportant des nanosphères métalliques ou semiconductrices. La seconde étude traite de la méthode d’extraction de la distribution du champ du plasmon sur la surface d’une nanosphère métallique excitée par une onde électromagnétique plane. Pour l’ensemble de ce travail nous avons tenu compte des paramètres caractéristiques de la matrice hôte et des nanoparticules sur l’indice effectif et le champ du plasmon calculésThis thesis is devoted to modeling of the optical properties of nanostructured dielectrics by metal particles. We interested in two aspects of the problem: the determination of effective index and field distribution of plasmon nanoparticles dispersed in such media. We have developed two numerical approaches. The first is devoted to the simulation of real and imaginary parts of the effective index of heterogeneous medium. In order to compare experience and theory, we have proposed an experimental approach to measure the effective refractive index of colloidal solutions containing metal or semiconductor nanospheres. The second aspect deals with the method of extraction of the field plasmon on the surface of metal nanosphere when it is excited by electromagnetic plane wave. The calculated effective index and field plasmon are done in function of characteristic parameters of nanoparticles and host matrix
Книги з теми "Particules nanostructurées":
1
Lin, Nian, and Sebastian Stepanow. Designing low-dimensional nanostructures at surfaces by supramolecular chemistry. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533046.013.10.
Анотація:
This article describes the use of supramolecular chemistry to design low-dimensional nanostructures at surfaces. In particular, it discusses the design strategies of two types of low-dimensional supramolecular nanostructures: structures stabilized by hydrogen bonds and structures stabilized by metal-ligand co-ordination interactions. After providing an overview of hydrogen-bond systems such as 0D discrete clusters, 1D chains, and 2D open networks and close-packed arrays, the article considers metal-co-ordination systems. It also presents experimental results showing that both hydrogen bonds and metal co-ordination offer protocols to achieve unique nanostructured systems on 2D surfaces or interfaces. Noting that the conventional 3D supramolecular self-assembly has generated a vast number of nanostructures revealing high complexity and functionality, the article suggests that 2D approaches can be applied to substrates with different symmetries as well as physical and chemical properties.
2
Glazov, M. M. Spin Systems in Semiconductor Nanostructures. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198807308.003.0002.
Анотація:
This chapter is an introduction to a rich variety of effects taking place in the interacting system of electrons and nuclei in semiconductors. It includes also the basics of electronic properties of nanostructures and of spin physics, an overview of fundamental interactions in the electron and nuclear spin systems, the selection rules at optical transitions in semiconductors, spin resonance effect, as well as optical orientation, and dynamical nuclear polarization. In this chapter an analysis of particular features of spin dynamics arising in the structures with localized electrons such as quantum dots, which are studied further in the book, are addressed. The aim of this chapter is to provide basic minimum of information needed to read the remaining chapters.
3
McGlynn, E., M. O. Henry, and J. P. Mosnier. ZnO wide-bandgap semiconductor nanostructures: Growth, characterization and applications. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533053.013.14.
Анотація:
This article describes the growth, characterization and applications of zinc oxide (ZnO) wide-bandgap semiconductor nanostructures. It first introduces the reader to the basic physics and materials science of ZnO, with particular emphasis on the crystalline structure, electronic structure, optical properties and materials properties of ZnO wide-bandgap semiconductors. It then considers some of the commonly used growth methods for ZnO nanostructures, including vapor-phase transport, chemical vapor deposition, molecular beam epitaxy, pulsed-laser deposition, sputtering and chemical solution methods. It also presents the results of characterization of ZnO nanostructures before concluding with a discussion of some promising areas of application of ZnO nanostructures, such as field emission applications; electrical, optical/photonic applications; and applications in sensing, energy production, photochemistry, biology and engineering.
4
Carter, Joshua D., Chenxiang Lin, Yan Liu, Hao Yan, and Thomas H. LaBean. DNA-based self-assembly of nanostructures. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533053.013.24.
Анотація:
This article examines the DNA-based self-assembly of nanostructures. It first reviews the development of DNA self-assembly and DNA-directed assembly, focusing on the main strategies and building blocks available in the modern molecular construction toolbox, including the design, construction, and analysis of nanostructures composed entirely of synthetic DNA, as well as origami nanostructures formed from a mixture of synthetic and biological DNA. In particular, it considers the stepwise covalent synthesis of DNA nanomaterials, unmediated assembly of DNA nanomaterials, hierarchical assembly, nucleated assembly, and algorithmic assembly. It then discusses DNA-directed assembly of heteromaterials such as proteins and peptides, gold nanoparticles, and multicomponent nanostructures. It also describes the use of complementary DNA cohesion as 'smart glue' for bringing together covalently linked functional groups, biomolecules, and nanomaterials. Finally, it evaluates the potential future of DNA-based self-assembly for nanoscale manufacturing for applications in medicine, electronics, photonics, and materials science.
5
Pennycook, S. J., M. Varela, M. F. Chisholm, A. Y. Borisevich, A. R. Lupini, K. van Benthem, M. P. Oxley, et al. Scanning transmission electron microscopy of nanostructures. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533053.013.6.
Анотація:
This article investigates nanostructures by means of scanning transmission electron microscopy. The electron microscope is uniquely suited to the study of individual nanostructures, allowing differentiation of different structures and properties that is difficult or impossible to do with techniques that provide a spatial average. The present generation of aberration correctors, which correct all aberrations up to third order, makes it possible to obtain sufficient sensitivity to image and spectroscopically analyze single atoms. This article begins with a brief overview of the correction of lens aberration in electron microscopy, followed by several examples of insights into nanomaterials and the atomic origins of their functionality. In particular, it considers semiconductor nanocrystals, semiconductor quantum wires, and nanocatalysts. It also discusses magnetism in gold and silver nanoclusters as well as charge ordering in manganites.
6
Deshpande, U. P., T. Shripathi, and A. V. Narlikar. Iron-oxide nanostructures with emphasis on nanowires. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533053.013.23.
Анотація:
This article examines the properties of iron-oxide nanostructures, with particular emphasis on nanowires. It begins with an overview of iron-oxide nanostructures and nanowires, followed by a discussion of the synthesis of aligned ?-Fe2O3 nanowires and nanosheets by a simple thermal oxidation route. It then describes the preferential bending of [110] grown ?-Fe2O3 nanowires about the C-axis and quantitative estimation of nanowire alignment using X-ray diffraction and grazing incidence X-ray diffraction. It also considers the growth mechanism of ?-Fe2O3 nanowires and nanosheets, different nanowire morphologies, rotational slip in ?-Fe2O3 nanosheets, and the influence of local environment and substrate microstructure on nanowire growth.
7
Vvedensky, Dimitri D. Quantum dots: Self-organized and self-limiting assembly. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533060.013.6.
Анотація:
This article describes the self-organized and self-limiting assembly of quantum dots, with particular emphasis on III–V semiconductor quantum dots. It begins with a background on the second industrial revolution, highlighted by advances in information technology and which paved the way for the era of ‘quantum nanostructures’. It then considers the science and technology of quantum dots, followed by a discussion on methods of epitaxial growth and fabrication methodologies of semiconductor quantum dots and other supported nanostructures, including molecular beam epitaxy and metalorganic vapor-phase epitaxy. It also examines self-organization in Stranski–Krastanov systems, site control of quantum dots on patterned substrates, nanophotonics with quantum dots, and arrays of quantum dots.
8
Blunt, MO, A. Stannard, E. Pauliac-Vaujour, CP Martin, Ioan Vancea, Milovan Suvakov, Uwe Thiele, Bosiljka Tadic, and P. Moriarty. Patterns and pathways in nanoparticle self-organization. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533046.013.8.
Анотація:
This article reviews relatively recent forms of self-assembly and self-organization that have demonstrated particular potential for the assembly of nanostructured matter, namely biorecognition and solvent-mediated dynamics. It first considers the key features of self-assembled and self-organized nanoparticle arrays, focusing on the self-assembly of nanoparticle superlattices, the use of biorecognition for nanoparticle assembly, and self-organizing nanoparticles. It then describes the mechanisms and pathways for charge transport in nanoparticle assemblies, with particular emphasis on the relationship between the current–voltage characteristics and the topology of the lattice. It also discusses single-electron conduction in nanoparticle films as well as pattern formation and self-organization in dewetting nanofluids.
9
Kartini, Indriana, Ahmad Kusumaatmaja, Tutik Dwi Wahyuningsih, Melati Khairuddean, and Roto Roto. Symposium of Materials Science and Chemistry III. Trans Tech Publications, Limited, 2021.
Частини книг з теми "Particules nanostructurées":
1
Tsuji, Nobuhiro, Shigenobu Ogata, Haruyuki Inui, Isao Tanaka, and Kyosuke Kishida. "Proposing the Concept of Plaston and Strategy to Manage Both High Strength and Large Ductility in Advanced Structural Materials, on the Basis of Unique Mechanical Properties of Bulk Nanostructured Metals." In The Plaston Concept, 3–34. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7715-1_1.
Анотація:
AbstractAdvanced structural materials are required to show both high strength and large ductility/toughness, but we have not yet acquired the guiding principle for that. The bulk nanostructured metals are polycrystalline metallic materials having bulky dimensions and average grain sizes smaller than 1 μm. Bulk nanostructured metals show very high strength compared with that of the coarse-grained counterparts, but usually exhibit limited tensile ductility, especially small uniform elongation below a few %, due to the early plastic instability. On the other hand, we have recently found that particular bulk nanostructured metals can manage high strength and large tensile ductility. In such bulk nanostructured metals, unusual deformation modes different from normal dislocation slips were unexpectedly activated. Unusual <c+a> dislocations, deformation twins with nano-scale thickness, and deformation-induced martensite nucleated from grain boundaries in the bulk nanostructured Mg alloy, high-Mn austenitic steel, and Ni-C metastable austenitic steel, respectively. Those unexpected deformation modes enhanced strain hardening of the materials, leading to high strength and large tensile ductility. It was considered that the nucleation of such unusual deformation modes was attributed to the scarcity of dislocations and dislocation sources in each recrystallized ultrafine grain, which also induced discontinuous yielding with clear yield drop universally recognized in bulk nanostructured metals having recrystallized structures. For discussing the nucleation of different deformation modes in atomistic scales, the new concept of plaston which considered local excitation of atoms under singular dynamic fields was proposed. Based on the findings in bulk nanostructured metals and the concept of plaston, we proposed a strategy for overcoming the strength-ductility trade-off in structural metallic materials. Sequential nucleation of different deformation modes would regenerate the strain-hardening ability of the material, leading to high strength and large tensile ductility. The strategy could be a guiding principle for realizing advanced structural materials that manage both high strength and large tensile ductility.
2
Edwards-Gayle, Charlotte J. C., and Jacek K. Wychowaniec. "Characterization of Peptide-Based Nanomaterials." In Peptide Bionanomaterials, 255–308. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-29360-3_8.
Анотація:
AbstractIn this chapter, we will thoroughly discuss characterization techniques used to elucidate the exact structure and define properties of peptide-based nanomaterials. In particular we divide methods into: Quality control performance (mass spectroscopy and high-performance liquid chromatography. Spectroscopy (Fourier transform infrared spectroscopy, Raman spectroscopy, circular and linear dichroism, nuclear magnetic resonance and fluorescence spectroscopy). Microscopy (scanning and transmission electron microscopies, atomic force microscopy, optical and polarized light microscopy). Scattering (small angle X-ray and neutron scattering, X-ray diffraction). Bulk structures (mainly hydrogels) rheological characterization. The methodology is described for molecular structures, self-assembled nanostructures and aggregates, as well as hybrid, composite and/or conjugated nanomaterials and their bulk forms. Both common, as well as more exotic versions of all methods are presented in the context of peptide-based nanomaterials. Where utilized, examples of combinatorial use of techniques are demonstrated. Representative studies accompany the discussion and usefulness of all presented methods.
3
Tsukanov, Alexey A., and Olga Vasiljeva. "Nanomaterials Interaction with Cell Membranes: Computer Simulation Studies." In Springer Tracts in Mechanical Engineering, 189–210. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60124-9_9.
Анотація:
AbstractThis chapter provides a brief review of computer simulation studies on the interaction of nanomaterialswith biomembranes. The interest in this area is governed by the variety of possible biomedical applications of nanoparticles and nanomaterials as well as by the importance of understanding their possible cytotoxicity. Molecular dynamics is a flexible and versatile computer simulation tool, which allows us to research the molecular level mechanisms of nanomaterials interaction with cell or bacterial membrane, predicting in silico their behavior and estimating physicochemical properties. In particular, based on the molecular dynamics simulations, a bio-action mechanism of two-dimensional aluminum hydroxide nanostructures, termed aloohene, was discovered by the research team led by Professor S. G. Psakhie, accounting for its anticancer and antimicrobial properties. Here we review three groups of nanomaterials (NMs) based on their structure: nanoparticles (globular, non-elongated), (quasi)one-dimensional NMs (nanotube, nanofiber, nanorod) and two-dimensional NMs (nanosheet, nanolayer, nanocoated substrate). Analysis of the available in silico studies, thus can enable us a better understanding of how the geometry and surface properties of NMs govern the mechanisms of their interaction with cell or bacterial membranes.
4
Hellmeier, Joschka, René Platzer, Johannes B. Huppa, and Eva Sevcsik. "A DNA Origami-Based Biointerface to Interrogate the Spatial Requirements for Sensitized T-Cell Antigen Recognition." In The Immune Synapse, 277–302. New York, NY: Springer US, 2023. http://dx.doi.org/10.1007/978-1-0716-3135-5_18.
Анотація:
AbstractWhen T cells scan the surface of antigen-presenting cells (APCs), they can detect the presence of just a few antigenic peptide/MHC complexes (pMHCs), in some cases even a single agonist pMHC. These are typically vastly outnumbered by structurally similar yet non-stimulatory endogenous pMHCs. How T cells achieve this enormous sensitivity and selectivity is still not clear, in particular in view of the rather moderate (1–100 μM) affinity that T-cell receptors (TCRs) typically exert for antigenic pMHCs. Experimental approaches that enable the control and quantification of physical input parameters within the context of the immunological synapse to precisely interrogate the molecular consequences of TCR-engagement, appear highly advantageous when searching for better answers.We here describe the implementation of a biointerface that allows to experimentally define molecular distances between T-cell ligands as a means to correlate them with molecular dynamics of antigen engagement, downstream signaling, and the overall T-cell response. The basis of this biointerface is DNA origami nanostructures, which are (i) rigid and highly versatile platforms that can (ii) be embedded as laterally mobile entities within supported lipid bilayers and functionalized (iii) in a site-specific and orthogonal manner with (iv) one or more proteins of choice.
5
Zolnikov, Konstantin P., Dmitrij S. Kryzhevich, and Aleksandr V. Korchuganov. "Regularities of Structural Rearrangements in Single- and Bicrystals Near the Contact Zone." In Springer Tracts in Mechanical Engineering, 301–22. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60124-9_14.
Анотація:
AbstractThe chapter is devoted to the analysis of the features of local structural rearrangementsin nanostructured materialsunder shear loadingand nanoindentation. The study was carried out using molecular dynamics-based computer simulation. In particular, we investigated the features of symmetric tilt grain boundary migration in bcc and fcc metals under shear loading. The main emphasis was on identifying atomic mechanisms responsible for the migration of symmetric tilt grain boundaries. We revealed that grain boundaries of this type can move with abnormally high velocities up to several hundred meters per second. The grain boundary velocity depends on the shear rate and grain boundary structure. It is important to note that the migration of grain boundary does not lead to the formation of structural defects. We showed that grain boundary moves in a pronounced jump-like manner as a result of a certain sequence of self-consistent displacements of grain boundary atomic planes and adjacent planes. The number of atomic planes involved in the migration process depends on the structure of the grain boundary. In the case of bcc vanadium, five planes participate in the migration of the Σ5(210)[001] grain boundary, and three planes determine the Σ5(310)[001] grain boundary motion. The Σ5(310)[001] grain boundary in fcc nickel moves as a result of rearrangements of six atomic planes. The stacking order of atomic planes participating in the grain boundary migration can change. A jump-like manner of grain boundary motion may be divided into two stages. The first stage is a long time interval of stress increase during shear loading. The grain boundary is motionless during this period and accumulates elastic strain energy. This is followed by the stage of jump-like grain boundary motion, which results in rapid stress drop. The related study was focused on understanding the atomic rearrangements responsible for the nucleation of plasticity near different crystallographic surfaces of fcc and bcc metals under nanoindentation. We showed that a wedge-shaped region, which consists of atoms with a changed symmetry of the nearest environment, is formed under the indentation of the (001) surface of the copper crystallite. Stacking faults arise in the (111) atomic planes of the contact zone under the indentation of the (011) surface. Their escape on the side free surface leads to a step formation. Indentation of the (111) surface is accompanied by nucleation of partial dislocations in the contact zone subsequent formation of nanotwins. The results of the nanoindentation of bcc iron bicrystal show that the grain boundary prevents the propagation of structural defects nucleated in the contact zone into the neighboring grain.
6
Colomban, Philippe. "Nano-optique, céramiques et verres nano-structurés, des pratiques millénaires." In Regards croisés: quand les sciences archéologiques rencontrent l'innovation, 99–122. Editions des archives contemporaines, 2017. http://dx.doi.org/10.17184/eac.3792.
Анотація:
L’optimisation des processus physiques (couleur, mécanique) et chimiques (réactivité, densification, homogénéité / hétérogénéité) mis en oeuvre dans les Arts du Feu (verres, céramiques, émaux) a conduit très tôt les potiers, verriers et émailleurs à rechercher dans la nature ou à fabriquer, de façon empirique mais efficace, des matières premières ultrafines, nanométriques et même à produire des matériaux nanostructurés. Après avoir expliqué les avantages des particules submicroniques et dressé un bref survol de l’histoire de l’usage des principaux produits nanométriques naturels (argile, amiante, pozzolanes, chaux, os, coquilles. . . ) et synthétiques (particules de cuivre, d’argent, d’or, de semi-conducteurs, de graphites et carbones. . . ) en technologies céramique, verrière et d’émaillage, la nanostructure et les propriétés optiques des premiers dispositifs nano-optiques – les lustres céramiques, IXe siècle – sont explicitées. En conclusion les nouveaux usages des nanoparticules en optique, santé ou matériaux de construction sont abordés.
7
Griffith Jones, Owen. "Protein Nanostructures." In Edible Nanostructures, 69–113. The Royal Society of Chemistry, 2014. http://dx.doi.org/10.1039/bk9781849738958-00069.
Анотація:
Proteins are one of the essential building blocks of biological structures at both the macro- and micro-scales, and many nanometer-sized protein structures are responsible for the basic functions of living systems. By understanding the attributes and potential interactivity of individual proteins one can design specific protein structures at the nanometer length-scale for advanced applications in food or medicine. In this chapter, major classes of protein nanostructures are discussed which have been developed over several decades of research. Of particular emphasis are the protein nanostructures that have been purposefully designed for use in medical or food applications, where it is most desirable to maintain reduced cost and natural sources. The nanostructures discussed include coacervates, self-assembled conjugates, desolvated nanoparticles, emulsion-templated nanoparticles, microgels, and fibrillar structures. By providing a cursory discussion on the principles of their formation and attributes of the finished nanoparticles, this chapter aims to provide perspective and potential inspiration for further development in protein-based nanoparticles.
8
Moreira de Sousa, José. "Nanostructures Failures and Fully Atomistic Molecular Dynamics Simulations." In Elasticity of Materials [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.100331.
Анотація:
Nowadays, the concern about the limitations of space and natural resources has driven the motivation for the development of increasingly smaller, more efficient, and energy-saving electromechanical devices. Since the revolution of “microchips”, during the second half of the twentieth century, besides the production of microcomputers, it has been possible to develop new technologies in the areas of mechanization, transportation, telecommunications, among others. However, much room for significant improvements in factors as shorter computational processing time, lower energy consumption in the same kind of work, more efficiency in energy storage, more reliable sensors, and better miniaturization of electronic devices. In particular, nanotechnology based on carbon has received continuous attention in the world’s scientific scenario. The riches found in different physical properties of the nanostructures as, carbon nanotubes (CNTs), graphene, and other exotic allotropic forms deriving from carbon. Thus, through classical molecular dynamics (CMD) methods with the use of reactive interatomic potentials reactive force field (ReaxFF), the scientific research conducted through this chapter aims to study the nanostructural, dynamic and elastic properties of nanostructured systems such as graphene single layer and conventional carbon nanotube (CNTs).
9
Henriques Ferreira, Sofia, Ana Rovisco, Andreia dos Santos, Hugo Águas, Rui Igreja, Pedro Barquinha, Elvira Fortunato, and Rodrigo Martins. "Porous ZnO Nanostructures Synthesized by Microwave Hydrothermal Method for Energy Harvesting Applications." In Nanopores [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97060.
Анотація:
The ever-growing global market for smart wearable technologies and Internet of Things (IoT) has increased the demand for sustainable and multifunctional nanomaterials synthesized by low-cost and energy-efficient processing technologies. Zinc oxide (ZnO) is a key material for this purpose due to the variety of facile methods that exist to produced ZnO nanostructures with tailored sizes, morphologies, and optical and electrical properties. In particular, ZnO nanostructures with a porous structure are advantageous over other morphologies for many applications because of their high specific surface area. In this chapter, a literature review on the latest progress regarding the synthesis and applications of ZnO with a porous morphology will be provided, with special focus on the synthesis by microwave hydrothermal method of these nanomaterials and their potential for application in energy harvesting devices. Nanogenerators of a composite made by polydimethylsiloxane (PDMS) and porous ZnO nanostructures were explored and optimized, with an output voltage of (4.5 ± 0.3) V being achieved for the best conditions. The daily life applicability of these devices was demonstrated by lighting up a commercial LED, by manually stimulating the nanogenerator directly connected to the LED.
10
Basu, Prasanta Kumar, Bratati Mukhopadhyay, and Rikmantra Basu. "Introduction." In Semiconductor Nanophotonics, 1–21. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780198784692.003.0001.
Анотація:
Abstract The present chapter gives an introduction to Nanophotonics. It starts with the definition of Electronics, and then describes its scope, progress, and current state-of the-art technology. After giving the definition of Photonics, a brief sketch of the development of Photonics is given mentioning how it opened up newer areas of development and applications and novel physical phenomena. The meaning and scope of Nanophotonics are then given, covering semiconductor nanostructures, photonic band gap structures, metallic nanostructures with emphasis on nanoantenna, plasmonics, metamaterials, and metasurfaces. The structures used in Nanophotonicsare then briefly introduced. A list of novel physical phenomena including cavity QED effects, Bose–Einstein condensation, etc., is then given. Finally, some of the envisaged application areas of Nanophotonics are discussed; in particular, the transition from Electronics to Photonics and ultimately to plasmonics in attaining small-size and high-speed systems for networking is briefly mentioned.
Тези доповідей конференцій з теми "Particules nanostructurées":
1
Hanawa, Y., Y. Sasaki, S. Uchida, T. Funayoshi, M. Otsuji, H. Takahashi, and A. Sakuma. "Thermomechanical Formulation of Freezing Point Depression Behavior of Liquid on Solid Surface With Nanostructure." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23759.
Анотація:
Abstract In this study, we investigated the freezing point depression of liquids in nanostructures using a new thermomechanical method. First, we experimentally determined the freezing points of water, cyclohexane, and a certain organic material (Chem.A) in nanoscale structures using DSC measurements. Thereafter, we formulated a new equation by improving the Gibbs–Thomson equation, which is the conventional formula for representing the freezing point depression of a liquid in nanostructures. We introduced a new term in this new equation to represent the increase in the kinetic energy of the liquid molecule as a result of collision between the liquid molecules and nanostructure walls. Subsequently, we evaluated the solid–liquid interface free energy of sublimation materials by fitting the theoretical freezing point derived from the new equation to experimental data. In this study, we succeeded in reproducing the experimental data of freezing point depression using the proposed equation. In particular, the freezing points of cyclohexane and Chem.A in the nanostructure were better fitted by this new equation at 10 nm or more compared with the conventional equation. Our results show that the interaction between the wall of the nanostructure and liquid molecules affects freezing point depression.
2
Wang, Evelyn N., Rong Xiao, Kuang-Han Chu, and Ryan Enright. "Nanoengineered Surfaces for Efficient Energy Systems." In ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2011. http://dx.doi.org/10.1115/icnmm2011-58300.
Анотація:
Nanoengineered surfaces offer new possibilities to manipulate fluid transport and enhance heat dissipation characteristics for the development of efficient energy systems. In particular, nanostructures on these surfaces can be harnessed to achieve superhydrophilicity and superhydrophobicity, and to control liquid behavior and phase-change processes. In this work, we will describe recent developments focused on using superhydrophilic nanostructure design to manipulate liquid spreading behavior and directionalities. In the presence of asymmetric nanopillars, uni-directional spreading of water droplets can be achieved where the liquid spreads only in the direction of the pillar deflection and becomes pinned on the opposite interface. In the presence of fine features on the pillars, we observed a multi-layer spreading effect due to their associated energy barriers. For both cases, we have developed energy-based models to accurately predict the liquid behavior as functions of pertinent parameters. Furthermore, we developed a semi-analytical model to predict liquid propagation rates in pillar arrays driven by capillarity. The results offer design guidelines to optimize propagation rates for fluidic wicks. These investigations offer insights and significant potential for the development and integration of advanced nanostructures to achieve efficient energy conversion systems.
3
Guru, D. N., M. Palacio, W. Mook, M. Chambers, J. Heberlein, W. Gerberich, O. Racek, and C. C. Berndt. "Nanophase Partially Stabilized Zirconia Intermediate Layer for Strain Accommodation in a Multi-layer Thermal Barrier Coating." In ITSC2004, edited by Basil R. Marple and Christian Moreau. ASM International, 2004. http://dx.doi.org/10.31399/asm.cp.itsc2004p0861.
Анотація:
Abstract Applying an environmental barrier coating (EBC) and a thermal barrier coating (TBC) on the next generation gas turbine structural materials such as silicon carbide matrix composites will lead to large stresses due to thermal expansion mismatch; thereby limiting the coating's effectiveness and lifetime. Nanostructured materials possess a large volume fraction of grain boundaries and are conjectured to partially relieve the strain in the coating structure. A Triple Torch Plasma Reactor (TTPR) was used to spray multi-layered TBCs consisting of a mullite EBC deposited either on a silicon carbide or a mullite substrate, a nano-phase partially stabilized zirconia coating (n- PSZ), and a yttria stabilized zirconia coating (YSZ) as the TBC. The nanostructure of the n-PSZ could be maintained during the deposition process. The coatings were heat treated at 1300°C and the change in microstructure and mechanical properties were analyzed using scanning electron microscopy (SEM), micro-indentation and scratch testing applied to the coating cross section. While a change in the microstructure was observed, in particular grain growth, the hardness and elastic modulus appeared to be little affected by the heat treatment giving a preliminary validation of the multilayer concept.
4
Deveaud, B., S. Haacke, M. Hartig, R. Ambigapathy, I. Bar Joseph, and R. A. Taylor. "Femtosecond luminescence of semiconductor nanostructures." In Quantum Optoelectronics. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/qo.1997.qthd.2.
Анотація:
Luminescence has been quite widely used for the study of semiconductor nanostructures, and more especially time resolved luminescence, due to the ease to get a luminescence signal. The interpretation of the results however is sometimes quite complex, and one generally finds that some care has to be taken for the results to be meaningful. In particular, the homogeneity of the excited density over the detected luminescence signal is a quite important parameter, also it is often desirable to work at the lowest possible densities.
5
Lavernia, Enrique J. "Thermal Spray Processing of Nanostructured Materials." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2695.
Анотація:
Abstract The application of nanocrystalline materials used as powder feedstock for thermal spraying in recent years has been mainly facilitated by the wide range of powder sources available, including: vapor condensation, solution precipitation, combustion synthesis, sol-gel processing, thermochemical synthesis, and mechanical alloying/milling. The resultant thermal sprayed coatings have been shown to exhibit unique and often enhanced physical and mechanical performance properties in comparison to the coatings produced by current technology. Improvements in physical have been documented for several metallic and cermet based nanostructured coatings. However, the behavior of a nanostructured material during thermal spraying is rendered complex by factors such as morphology of feedstock powders; thermal stability of nanostructured powders; and thermal and momentum behavior of nanostructured powder. Optimization of chemistry, morphology and coating thickness, for example, should lead to the attainment of physical performance heretofore unattainable with conventional coatings. The present paper is to provide an overview of recent advancements in the field of high performance nanostructured coatings, paying particular attention to underlying fundamental issues. Examples of several metallic and cermet coatings will be used to demonstrate the influence of the morphology of nanostructured powders on the performance of the sprayed coatings.
6
Shavik, Sheikh Mohammad, Mohammad Nasim Hasan, and A. K. M. Monjur Morshed. "Molecular Dynamics Study on Explosive Boiling of Thin Liquid Argon Film on Nanostructured Surface Under Different Wetting Conditions." In ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icnmm2015-48352.
Анотація:
Molecular dynamics (MD) simulations have been performed to investigate the boiling phenomena of thin liquid film adsorbed on a nanostructured solid surface with particular emphasis on the effect of wetting condition of the solid surface. The molecular system consists of liquid and vapor argon, and solid platinum wall. The nanostructures which reside on top of the solid wall have shape of rectangular block. The solid-liquid interfacial wettability, in other words whether the solid surface is hydrophilic or hydrophobic has been altered for different cases to examine its effect on boiling phenomena. The initial configuration of the simulation domain comprised a three phase system (solid platinum, liquid argon and vapor argon) which was equilibrated at 90 K. After equilibrium period, the wall temperature was suddenly increased from 90 K to 250 K which is far above the critical point of argon and this initiates rapid or explosive boiling. The spatial and temporal variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for different cases of wetting conditions of solid surface. The results show that the wetting condition of surface has significant effect on explosive boiling of the thin liquid film. The surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in case of hydrophilic surface.
7
Żórawski, W., T. Burakowski, and S. Skrzypek. "Tribological Properties of HVOF Sprayed Nanostructured Composite Coatings." In ITSC2011, edited by B. R. Marple, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and A. McDonald. DVS Media GmbH, 2011. http://dx.doi.org/10.31399/asm.cp.itsc2011p0740.
Анотація:
Abstract Nanostructured materials are of particular scientific interest because of their physical and mechanical properties, which are superior to those of conventional materials. They are more widely used in various industrial applications mainly due to decreasing production costs. The work is concerned with a study of the tribological properties of a HVOF sprayed composite of nanostructured WC12Co mixed with nanostructured Fe3O4, having the properties of solid lubricant. The coatings were sprayed by means of a Hybrid Diamond Jet system. A T-01 ball on disc tribological tester was used to study their resistance to wear and determine the coefficient of friction on the basis of friction force obtained in the course of continuous measurement at a set load. Result of investigations were compared with properties of coatings sprayed with standard WC12Co/ Fe3O4. The microstructures and compositions of the nanostructured powders and coatings were analyzed by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. Their phase composition was studied using a Bruker D8 Advance diffractometer.
8
Takeuchi, Hiroki, Junfeng Yue, Keisuke Imaeda, and Kosei Ueno. "Near-field spectral properties and ultrafast dynamics of coupled plasmonic nanostructures." In Conference on Lasers and Electro-Optics/Pacific Rim. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleopr.2022.p_cm16_12.
Анотація:
We are studying the effects of localization of electromagnetic field and extension of plasmon lifetime on the near-field enhancement. In particular, the plasmon lifetime can be controlled by coupling with long-lived optical modes or excitons. In this study, we elucidated the near-field spectral characteristics and phase relaxation dynamics of coupled plasmonic nanostructures and the effect of plasmon dephasing dynamics on near-field enhancement.
9
da Silva, Carlos, Julia Sborz, David A. Romero, and Cristina H. Amon. "Predicting Phonon Transport in Two-Dimensional Boron Nitride-Graphene Superlattices." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-37326.
Анотація:
The synthesis of boron nitride (BN) - graphene hybrid materials is now a reality that has opened opportunities for creation of new nanostructures with enhanced mechanical, electronic and thermal properties, of particular interest for nanoelectronics applications. Properties of these materials are still not well understood, and modelling approaches are needed to support engineering design of these novel nanostructures. In this work, we study thermal transport in BN-graphene superlattices from a phonon transport perspective. We predict phonon properties (phonon group velocities and phonon lifetimes) using normal mode analysis based on phonon spectral energy density (SED) in these superlattices, with especial emphasis on the role of the orientation of the atoms at the BN - graphene interfaces. We consider various superlattices compositions with two highly symmetric orientation, i.e., zig-zag and armchair. Our results show that phonon group velocities are higher for the zig-zag interface orientation. We also found that phonon modes at small frequencies are more sensitive to the superlattice configurations.
10
Majidi, Carmel, Mikko Haataja, and David J. Srolovitz. "Energy Harvesting With Piezoelectric Nanobrushes: Analysis and Design Principles." In ASME/STLE 2009 International Joint Tribology Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/ijtc2009-15210.
Анотація:
The development of self-powered electronic devices is essential for emerging technologies such as wireless sensor networks, wearable electronics, and microrobotics. Of particular interest is the rapidly growing field of piezoelectric energy harvesting (PEH), in which mechanical strains are converted to electricity. Recently, PEH has been demonstrated by brushing an array of piezoelectric nanowires against a nanostructured surface. The piezoelectric nanobrush generator can be limited to sub-micron dimensions and thus allows for a vast reduction in the size of self-powered devices. Moreover, energy harvesting is controlled through contact between the nanowire tips and nanostructured surface, which broadens the design space to a wealth of innovations in tribology. Here we propose design criteria based on principles of contact mechanics, elastic rod theory, and continuum piezoelasticity.