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Статті в журналах з теми "Patchy nanoparticles"
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Liu, Bin, Stéphanie Exiga, Etienne Duguet, and Serge Ravaine. "Templated Synthesis and Assembly of Two-, Three- and Six-Patch Silica Nanoparticles with a Controlled Patch-to-Particle Size Ratio." Molecules 26, no. 16 (August 5, 2021): 4736. http://dx.doi.org/10.3390/molecules26164736.
Повний текст джерелаАнотація:
We report a fabrication route of silica nanoparticles with two, three or six patches with an easily tunable patch-to-particle size ratio. The synthetic pathway includes two main stages: the synthesis of silica/polystyrene multipod-like templates and the selective growth of their silica core through an iterative approach. Electron microscopy of the dimpled nanoparticles obtained after dissolution of the polystyrene nodules of the multipod-like nanoparticles provides evidence of the conformational growth of the silica core. Thanks to the presence of some polymer chains, which remained grafted at the bottom of the dimples after the dissolution of the PS nodules, the solvent-induced assembly of the patchy nanoparticles is performed. Chains, hexagonal suprastructures and cubic lattices are obtained from the assembly of two-, three- and six-patch silica nanoparticles, respectively. Our study can guide future work in both patchy nanoparticle synthesis and self-assembly. It also opens new routes towards the fabrication of specific classes of one-, two- and three-dimensional colloidal lattices, including complex tilings.
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Gong, Shuting, Tianyi Wang, Jiaping Lin, and Liquan Wang. "Patterning of Polymer-Functionalized Nanoparticles with Varied Surface Mobilities of Polymers." Materials 16, no. 3 (February 1, 2023): 1254. http://dx.doi.org/10.3390/ma16031254.
Повний текст джерелаАнотація:
The polymers can be either dynamically tethered to or permanently grafted to the nanoparticle to produce polymer-functionalized nanoparticles. The surface mobility of polymer ligands with one end anchored to the nanoparticle can affect the surface pattern, but the effect remains unclear. Here, we addressed the influence of lateral polymer mobility on surface patterns by performing self-consistent field theory calculations on a modeled polymer-functionalized nanoparticle consisting of immobile and mobile brushes. The results show that except for the radius of nanoparticles and grafting density, the fraction of mobile brushes substantially influences the surface patterning of polymer-functionalized nanoparticles, including striped patterns and patchy patterns with various patches. The number of patches on a nanoparticle increases as the fraction of mobile brushes decreases, favored by the entropy of immobile brushes. Critically, we found that broken symmetry usually occurs in patchy nanoparticles, associated with the balance of enthalpic and entropic effects. The present work provides a fundamental understanding of the dependence of surface patterning on lateral polymer mobility. The work could also guide the preparation of diversified nanopatterns, especially for the asymmetric patchy nanoparticles, enabling the fundamental investigation of the interaction between polymer-functionalized nanoparticles.
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Bianchi, Emanuela, Barbara Capone, Gerhard Kahl, and Christos N. Likos. "Soft-patchy nanoparticles: modeling and self-organization." Faraday Discussions 181 (2015): 123–38. http://dx.doi.org/10.1039/c4fd00271g.
Повний текст джерелаАнотація:
We consider a novel class of patchy particles inspired by polymer-based complex units where the limited valence in bonding is accompanied by soft interactions and incessant fluctuations of the patch positions, possibly leading to reversible modifications of the patch number and size. We introduce a simple model that takes into account the aforementioned features and we focus on the role played by the patch flexibility on the self-organization of our patchy units in the bulk, with particular attention to the connectivity properties and the morphology of the aggregated networks.
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Choueiri, Rachelle M., Elizabeth Galati, Anna Klinkova, Héloïse Thérien-Aubin, and Eugenia Kumacheva. "Linear assembly of patchy and non-patchy nanoparticles." Faraday Discussions 191 (2016): 189–204. http://dx.doi.org/10.1039/c6fd00057f.
Повний текст джерелаАнотація:
Linear assemblies of nanoparticles show promising applications due to their collective electronic, optical and magnetic properties. Rational design and controllable organization of nanoparticles in one-dimensional structures can strongly benefit from the marked similarity between conventional step-growth polymerization reactions and directional step-wise assembly of nanoparticles in linear chains. Here we show different aspects of the “polymerization” approach to the solution-based self-assembly of polymer-functionalized metal nanoparticles with different chemical compositions, shapes and dimensions. The self-assembly was triggered by inducing solvophobic attraction between polymer ligands, due to the change in solvent quality. We show that both anisotropic (patchy) nanoparticles and nanoparticles uniformly capped with polymer molecules can self-assemble in linear chains. We explore the control of chain length, morphology, and composition, discuss the ability to form isotropic and hierarchical structures and show the properties and potential applications of linear assemblies of plasmonic nanoparticles.
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Liu, Bin, Etienne Duguet, and Serge Ravaine. "Solvent-induced assembly of mono- and divalent silica nanoparticles." Beilstein Journal of Nanotechnology 14 (January 6, 2023): 52–60. http://dx.doi.org/10.3762/bjnano.14.6.
Повний текст джерелаАнотація:
Particles with attractive patches are appealing candidates to be used as building units to fabricate novel colloidal architectures by self-assembly. Here, we report the synthesis of one-patch silica nanoparticles, which consist of silica half-spheres whose concave face carries in its center a polymeric patch made of grafted polystyrene chains. The multistage synthesis allows for a fine control of the patch-to-particle size ratio from 0.23 to 0.57. The assembly of the patchy nanoparticles can be triggered by reducing the solvent quality for the polystyrene chains. Dimers or trimers can be obtained by tuning the patch-to-particle size ratio. When mixed with two-patch nanoparticles, one-patch nanoparticles control the length of the resulting chains by behaving as colloidal chain stoppers. The present strategy allows for future elaboration of novel colloidal structures by controlled assembly of nanoparticles.
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Rouet, Pierre-Etienne, Cyril Chomette, Laurent Adumeau, Etienne Duguet, and Serge Ravaine. "Colloidal chemistry with patchy silica nanoparticles." Beilstein Journal of Nanotechnology 9 (December 6, 2018): 2989–98. http://dx.doi.org/10.3762/bjnano.9.278.
Повний текст джерелаАнотація:
We report a new route to synthesize clusters, or so-called colloidal molecules (CMs), which mimic the symmetry of molecular structures made of one central atom. We couple site-specifically functionalized patchy nanoparticles, i.e., valence-endowed colloidal atoms (CAs), with complementary nanospheres through amide bonds. By analogy with the Gillespie formalism, we show that AX4, AX3E1 and AX2E2 CMs can be obtained from tetravalent sp3-like CAs when the relative amount of both building units is varied in a controlled manner. We obtain AX2 CMs from divalent sp-like CAs. We also show that it is possible to covalently attach two different types of satellites to the same central patchy nanoparticle to create more complex CMs, opening the way to the fabrication of new multifunctional nanostructures with well-controlled shape and composition.
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Galati, Elizabeth, Huachen Tao, Christian Rossner, Ekaterina B. Zhulina, and Eugenia Kumacheva. "Morphological Transitions in Patchy Nanoparticles." ACS Nano 14, no. 4 (March 16, 2020): 4577–84. http://dx.doi.org/10.1021/acsnano.0c00108.
Повний текст джерела
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Yi, Chenglin, Hong Liu, Shaoyi Zhang, Yiqun Yang, Yan Zhang, Zhongyuan Lu, Eugenia Kumacheva, and Zhihong Nie. "Self-limiting directional nanoparticle bonding governed by reaction stoichiometry." Science 369, no. 6509 (September 10, 2020): 1369–74. http://dx.doi.org/10.1126/science.aba8653.
Повний текст джерелаАнотація:
Nanoparticle clusters with molecular-like configurations are an emerging class of colloidal materials. Particles decorated with attractive surface patches acting as analogs of functional groups are used to assemble colloidal molecules (CMs); however, high-yield generation of patchy nanoparticles remains a challenge. We show that for nanoparticles capped with complementary reactive polymers, a stoichiometric reaction leads to reorganization of the uniform ligand shell and self-limiting nanoparticle bonding, whereas electrostatic repulsion between colloidal bonds governs CM symmetry. This mechanism enables high-yield CM generation and their programmable organization in hierarchical nanostructures. Our work bridges the gap between covalent bonding taking place at an atomic level and colloidal bonding occurring at the length scale two orders of magnitude larger and broadens the methods for nanomaterial fabrication.
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Ramírez-Acosta, Carlos M., Javier Cifuentes, Juan C. Cruz, and Luis H. Reyes. "Patchy Core/Shell, Magnetite/Silver Nanoparticles via Green and Facile Synthesis: Routes to Assure Biocompatibility." Nanomaterials 10, no. 9 (September 17, 2020): 1857. http://dx.doi.org/10.3390/nano10091857.
Повний текст джерелаАнотація:
Nanomedicine is entering a high maturity stage and is ready to reach full translation into the clinical practice. This is because of the ample spectrum of applications enabled by a large arsenal of nanostructured materials. In particular, bimetallic patchy core/shell nanoparticles offer tunable surfaces that allow multifunctional responses. Despite their attractiveness, major challenges regarding the environmental impact and biocompatibility of the obtained materials are yet to be solved. Here, we developed a green synthesis scheme to prepare highly biocompatible patchy core/shell magnetite/silver nanoparticles for biological and biomedical applications. The magnetite core was synthesized by the co-precipitation of ferric chloride and ferrous chloride in the presence of NaOH. This was followed by the patchy silver shell’s growth by a green synthesis approach based on natural honey as a reducing agent. A purification process allowed selecting the target patchy nanoparticles and removing excess toxic reagents from the synthesis very efficiently. The obtained patchy magnetite/silver nanoparticles were characterized by UV-Vis spectrophotometry, dynamic light scattering (DLS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope equipped with energy-dispersive spectroscopy (SEM + EDS), and transmission electron microscopy (TEM). The morphology, patchiness level, and size of the nanoparticles were determined via SEM and TEM. In addition, the spectrophotometric characterization confirmed the presence of the patchy silver coating on the surface of the magnetite core. The nanoparticles show high biocompatibility, as evidenced by low cytotoxicity, hemolytic effect, and platelet aggregation tendency. Our study also provides details for the conjugation of multiples chemistries on the surface of the patchy bimetallic nanoparticles, which might be useful for emerging applications in nanomedicine, where high biocompatibility is of the utmost importance.
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Striolo, Alberto, Jongwook Kim, Luis Liz-Marzán, Luciano Tadiello, Matthias Pauly, Catherine Murphy, Anna Roig, et al. "Janus and patchy nanoparticles: general discussion." Faraday Discussions 191 (2016): 117–39. http://dx.doi.org/10.1039/c6fd90048h.
Повний текст джерелаДисертації з теми "Patchy nanoparticles"
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Herman, David Joel. "Stabilization of weakly charged microparticles using highly charged nanoparticles." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/34345.
Повний текст джерелаАнотація:
An experimental investigation was conducted to evaluate the possible use of highly-charged spherical nanoparticles to stabilize an aqueous dispersion of weakly-charged microspheres. At low pH values, the surface of silica is weakly charged, which leads to flocculation of colloidal suspensions of silica microspheres. Binary solutions of weakly charged silica microspheres and highly charged polystyrene latex nanoparticles result in adsorption of the nanoparticles onto the surface of the silica microspheres. This effectively â rechargesâ the silica spheres, with effective zeta potentials increased to the range that is unfavorable for flocculation of microspheres in a silica-only solution. However, this does not guarantee stability, and comparisons between positively charged amidine latex nanoparticles and negatively charged sulfate latex nanoparticles indicate that the degree of coverage plays an important role in the restabilization. The sulfate latex nanoparticles do not cover the surface sufficiently, and though they seemingly provide sufficient charge, the weakly charged patches of the exposed silica substrate can lead to flocculation. The amidine latex nanoparticles, on the other hand, cover the surface more completely, and effectively prevent flocculation of the silica microspheres. The mechanisms responsible for this different adsorption and stabilizing behavior are not entirely understood, as both the amidine and sulfate latex nanoparticles are of similar size and the magnitude of the zeta potentials of the different particle types are comparable.Master of Science
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Ferrie, Mélanie. "Design de particules plasmoniques pour le contrôle de l’absorption et de l’émission de lumière." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14410/document.
Повний текст джерелаАнотація:
Au cours ce travail, nous nous sommes intéressés au design de particules plasmoniques pour le contrôle de l’absorption et de l’émission de lumière. Notre stratégie a été de synthétiser des nanoparticules de type cœur@écorce composées d’un cœur d’or et d’une écorce diélectrique de silice contenant des molécules organiques fluorescentes. Nous avons fait varier la distance entre ces dernières et le cœur afin de moduler l’intensité de leur couplage avec les plasmons du métal et d’ainsi contrôler les propriétés optiques des nanoparticules. Nous nous sommes aussi intéressés à l’assemblage de ces nanoparticules sous la forme de supra-particules ou de réseaux bidimensionnels organisés. L’étude des propriétés optiques de ces nouveaux matériaux a permis de mettre en évidence une forte exaltation de l’intensité de fluorescence des particules cœur@écorce quand celles-ci sont confinées entre deux nappes métalliques, ce qui correspond à un mode de cavité fort. Nous avons également travaillé sur la synthèse de particules composées d’un cœur de silice et soit d’une écorce d’or présentant des patchs « vierges », soit d’une écorce de dioxyde de titane comportant des patchs recouverts de nanoparticules d’orDuring this work, we were interested in the design of plasmonic particles for the control of the absorption and the emission of light. Our strategy was to synthesize core@shell nanoparticles made of a gold core and a silica shell containing fluorescent organic molecules. We have varied the distance between the emitters and the core in order to tune their coupling with the plasmons of gold. We thus tuned the optical properties of the particles. We were also interested in the assembly of these nanoparticles to get supra-particles or organized two-dimensional networks. The study of optical properties of these new materials showed that the exaltation of the fluorescence is maximal when the core@shell particles are confined between two gold boundaries, this situation corresponding to a strong cavity mode. We also worked on the synthesis of particles consisting of a silica core and either a gold shell with bare patches or a titanium dioxide shell with patches covered with gold nanoparticles
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Lemaître, Caroline. "Contribution à l'étude théorique, numérique et expérimentale des nanoantennes patch optiques." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22742/document.
Повний текст джерелаАнотація:
Dans le domaine des biocapteurs, une absorption efficace du champ électromagnétique dans un espace restreint est essentielle. L’utilisation de nanoparticules métalliques assimilables à des métamatériaux est le meilleur moyen à ce jour pour amplifier le champ. En effet, en plaçant un film diélectrique entre une plaque métallique et ces particules, on permet la propagation d’un gap-plasmon sous les particules. Cela localise le champ magnétique sous les particules et le champ électrique sur le bords de ces nanoparticules. Les résonances de ce système sont très sensible à l’environnement du gap-plasmon ce qui permet une analyse très précise. Bien que nous pouvons expliquer d’où proviennent ces résonances, l’efficacité à absorber de ces structures reste encore mal comprise. Le contrôle interférométrique est une réponse à cette efficacité. Dans ce rapport, je montre qu’une modélisation interférométrique de ce système peut parfaitement expliquer l’absorption. En effet, le contrôle interférométrique explique bien la présence de résonances à des longueurs d’ondes précises ou encore l’apparition de résonances lorsque l’angle d’incidence n’est plus normal. Cette étude est très importante pour comprendre et mieux maîtriser les biocapteurs. En outre, cette modélisation pourra expliquer l’amplification du champ dans ces structures et permettra de prévoir les résonances d’un système dans divers environnementsIn the field of biosensors, efficient absorption of the electromagnetic field in a confined space is essential. The use of metallic nanoparticules comparable to metamaterials is the best way, to date, to amplify the field. In fact, by placing a dielectric film between a metal substrate and these particules, we allow the propagation of a gap-plasmon under these particules. This locates the magnetic field under these particules and the electric field on the edges of these nanoparticules. The resonances of this system are very sensitive to the environment of the gap-plasmon which allows very precise analysis. Although we can explain where these resonances come from, the efficiency to absorb of these structures remains poorly understood. The interferometric control is a response to this efficiency. In this report, I show that interferometric modeling of this system can fully explain the absorption. Indeed, the interferometric control well explains the presence of resonances at specific wavelenghts or the appearance of resonances when the angle of incidence is not normal. This study is very important to understand and master biosensors. In addition, this model can explain the amplification of the field in these structures and will allow us to provide the resonances of a system in various environments
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Palis, Hervé. "Nanoparticules de silice à patchs : optimisation de leur synthèse et de leur assemblage, et observation in situ." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0347.
Повний текст джерелаАнотація:
Cette étude porte sur l’auto-assemblage de nanoparticules de silice à patchs cavitaires en vue d’obtenir de nouvelles molécules colloïdales. Dans un premier temps, les briques élémentaires, à savoir des particules à patchs et des particules satellites ont été synthétisées. Ce travail s’est focalisé sur des particules à quatre patchs dont la pureté morphologique a été améliorée tant par l’optimisation de la fonctionnalisation de surface des germes utilisés lors de l’étape de polymérisation ensemencée que par une étape de purification par centrifugation en gradient de densité. Des molécules colloïdales constituées d’une particule à patchs entourée de nanoparticules satellites en nombre contrôlé ont été obtenues par assemblage covalent. La chimie d’assemblage a été simplifiée en réduisant le nombre d’étapes de fonctionnalisation aussi bien pour les chaînes de polystyrène ancrées au fond des cavités que pour la surface des particules satellites. Des molécules colloïdales imitant des molécules d’eau ont pu être fabriquées en ajustant le rapport entre le nombre de particules satellites et le nombre de cavités. La taille nanométrique des particules mises en jeu empêche leur observation par microscopie optique. C’est pourquoi ces travaux ont également porté sur le développement expérimental de la technique de microscopie électronique en transmission en voie liquide dans le but ultime d’observer la dynamique d’assemblage des briques élémentairesThis study deals with the self-assembly of dimpled patchy particles to get new colloidal molecules. First, building blocks – patchy silica nanoparticles and satellite particles - were synthesized. This work was focused on particles bearing four patches whose morphological purity was increased not only by optimizing the surface functionalization of the seeds used during the seeded growth emulsion polymerization stage, but also by purification by density gradient centrifugation. Covalent chemistry allowed obtaining colloidal molecules consisting of a four-patch particle surrounded by controlled number of satellite nanoparticles. The chemical pathway was simplified by reducing the number of functionalization steps for the polystyrene chains anchored at the bottom of the dimples and for the surface of the satellite particles. Colloidal molecules whose morphology mimics that of water molecules were fabricated by adjusting the ratio between the number of satellite particles and the number of dimples. Due to the sizes of the particles involved, dynamics of assembly cannot be followed by optical microscopy. This is why the technique of transmission electron microscopy in liquid phase was also investigated
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CARDELLINI, ANNALISA. "Modelling of Multi-Scale Phenomena in Nanoparticle Suspensions." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2687171.
Повний текст джерелаАнотація:
Self- or driven-assembly of nanoparticles (NPs) into mesoscopic ordered structures play a crucial role in a large variety of applications including energy, pharmaceutical,
food, drug delivery, immunology and technological. On the one hand, trying to prevent and avoid the self-organization of nanoparticles has traditionally been the main issue to stabilizing nanosuspensions, foams, and emulsions. On the other hand, the aggregation of building-blocks into mesoscopic structures has allowed to explore new materials with desired functionalities and properties. In the latter context, a proper attention has been devoted to the dominant role of aggregation in altering the thermal properties of nanosuspensions. However, due to the challenges of controlling the inter-particle interactions and the process of aggregation, clear guidelines for a rational design of tailored suspensions is still missing. Accurately modelling heat and mass transport phenomena across many different length scales is essential to optimize the self-assembly and stability of colloidal suspensions. In this thesis, Molecular Dynamics (MD) simulations, Coarse-Grained (CG) techniques, Brownian Dynamics (BD) and theoretical modelling studies are combined to understand how the interfacial phenomena influence the mechanisms of building-block interactions and hence how to predict the shapes of assembled clusters and their related macroscopic properties. First, the behaviour of nanoconfined water and the adsorption of ionic surfactants at the solid-liquid nanoscale interface are investigated. Second, atomistic Potentials of Mean Force (PMFs) are evaluated between couples of NPs dispersed in aqueous solutions. A sensitivity analysis is carried out by altering the hydrophilicity of the nanoparticles, their surface charge and the salt concentration of the bulk solution. Moreover, the role of anionic (Sodium Dodecyl Sulphate -SDS-) and
cationic (Dodecyl Trimethyl Ammonium -DTAB-) surfactants is included in the evaluation of the PMF. All the study cases are then compared with the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, and remarkable discrepancies have emerged, underling the limits of a continuum theory to model the colloidal interactions at the nanoscale. In particular, the results highlight that the assumption of a uniform and continuum media and the hypothesis of homogeneous particles present in the DLVO theory break down at the solid-liquid nanoscale interface and by considering patchy NPs after surfactant adsorption. Thus, MD simulations offer the best alternatives to capture all coupled phenomena included in NP interactions. Subsequently, the atomistic PMFs are implemented in a multi-scale model, where MD simulations and Brownian dynamics are integrated offering a detailed picture of the kinetic of NP aggregation. The qualitative agreement with the experimental observations validates the novel multi-scale platform, able to connect the nanoscale features to the size of aggregates and related macroscopic properties of colloidal suspensions. Finally, with a coarse-grained technique, a force field for heterogeneous
NPs is also provided. Thus, in the present work, powerful tools and multi-scale modelling approaches are developed to describe some of the multi-scale phenomena
occurring in NP suspensions. Clear guidelines to perform multi-scale simulations of the self-assembly processes are proposed, and the first step towards a rational design
of NP suspensions is presented.
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Chomette, Cyril. "Design et fabrication de meta-atomes plasmoniques à partir de nanoparticules à patchs." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0232/document.
Повний текст джерелаАнотація:
Les méta-matériaux sont une nouvelle classe de matériaux composites artificiels quiprésentent des propriétés inédites. Ils sont typiquement sous divisés en unité appelées méta-atomes.Un design approprié de ces méta-atomes, architecturés à l’échelle nanométrique, permet d’induire despropriétés aussi extraordinaires qu’un indice de réfraction négatif. Dans ce contexte, nous avonsdéveloppé des particules à patchs, capable de développer des interactions selon des directionsprédéterminées. Des clusters multipodiques fait de ces particules (diélectrique) entourées d’un nombrecontrôlé de satellites plasmoniques (or) ont été développés. Nous nous sommes focalisés sur desclusters isotropes, dérivant de géométries tétraédriques, octaédriques et icosaédriques (trois des cinqsolides de Platon). Pour cela, nous avons utilisé des clusters silice/polystyrène, obtenus parpolymérisation ensemencée en émulsion, qui ont servi de préformes. Ils ont ainsi permis d’obtenir desparticules dont les patchs sont en fait des fossettes au fond desquelles subsiste un résidu de chaînespolystyrène greffées. En modifiant chimiquement ces chaînes, nous avons permis soit l’accrochage aufond de ces fossettes de colloïdes d’or puis leur croissance, soit l’accostage de satellites de silice surlesquels nous avons ensuite fait croître une coquille d’or. La seconde voie à offert un meilleur contrôlede la morphologie des clusters et notamment de la distance entre les satellites d’or (quelquesnanomètres) qui est primordiale pour assurer un couplage plasmonique optimal. Les propriétés desclusters obtenus ont été modélisées et mesuréesMetamaterials are a novel class of artificial composite materials, typically made of subunit called meta-atoms and exhibiting unusual properties. Such meta-atoms, have to be architecturedat the nanometric level, to induce as extraordinary properties as a negative refractive index. In thiscontext, we developed patchy particles, capable to create interactions along predetermined directions.Multipodic clusters made of those (dielectric) particles surrounded by a controlled number ofplasmonic satellites (gold) were developed. We focused on isotropic clusters deriving fromtetrahedral, octahedral and icosahedral geometry (three of the fifth Platonic solids). For that purpose,we used silica/polystyrene clusters, obtained from seeded emulsion polymerization, as template. Byderiving those clusters, patchy particles bearing dimples containing grafted residual polystyrene chainswere obtained. By chemically deriving those chains, we explored two synthetic pathways, thedecoration of the dimples with gold colloids subsequently grown or the anchoring of silica satellitesonto which gold shells were subsequently grown. The second one was prove to offer a better controlover the cluster morphology as well as the inter-satellites gap (few nanometer) which is pivotal toensure an optimal plasmonic coupling. Then, the optical properties of the as obtained clusters weresimulated and measured
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Li, Weiya. "Assemblage induit en milieu solvant de nanoparticules de silice à patchs : vers de nouvelles molécules colloïdales." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0127.
Повний текст джерелаАнотація:
Cette étude porte sur l’assemblage de particules à patchs pour obtenir de nouveaux matériaux. L’étatde l’art a permis de choisir et de mettre en oeuvre une stratégie originale dont la force motrice est l’assemblageinduit en milieu solvant, c’est-à-dire basé sur le caractère collant des macromolécules de polystyrène (PS)lorsqu’elles sont soumises à un mélange d’un bon et d’un mauvais solvant. Nous avons étudié l’assemblage enclusters, en chaînes ou en monocouches de nanoparticules (NPs) de silice possédant respectivement un, deux outrois patchs, constitués de macromolécules de PS greffées à des endroits spécifiques de leur surface. Les NPs desilice à un patch, présentant un rapport de taille patch/particule contrôlable, ont été synthétisées avec succès parune étape de séparation de phases induit par gonflement suivie d’un dépôt de silice régiosélectif. Leur assemblagea été réalisé dans des mélanges binaires DMF/éthanol. Les effets de la qualité du solvant, de la force decentrifugation, de la concentration en NPs, de la durée d'incubation et du rapport de taille patch/particule ont étéétudiés et discutés. La stratégie a été étendue pour obtenir des clusters à base d’or. Les NPs de silice à deuxpatchs ont été préparées par un procédé de polymérisation en émulsion ensemencée du styrène et le rapport detaille patch/particule a été ajusté via le taux de recroissance du noyau de silice. L’assemblage en chaînes des NPsa été réalisé dans des mélanges THF/solution aqueuse de NaCl en faisant varier la concentration en NaCl, lerapport volumique THF/eau, la durée d’incubation, la concentration en NPs et le rapport de tailles patch/particule.Nous avons montré que la cinétique de croissance des chaînes est typique d’une croissance par étapes. Desstratégies pour imiter des homopolymères, des copolymères statistiques, des copolymères séquencés à blocs etdes polymères ramifiés ont été mises en oeuvre, en utilisant comme briques de base des NPs à un patch, des NPsà deux patchs avec des tailles ou des fonctions de surface différentes et/ou des NPs à trois patchs. Les NPs desilice à trois patchs ont été obtenues par la même voie de synthèse que celles à deux patchs. Pour les assemblerdans des structures 2-D en nid d'abeille, nous avons utilisé la technique de Langmuir et nous avons étudiél'influence de différents paramètres expérimentaux. Une étape de recuit sous vapeur de THF a été mise en oeuvre,ce qui a permis de renforcer mécaniquement l’assemblage, mais sans effet significatif sur la compacitéThis study deals with the assembly of patchy particles to get new materials. The state-of-the-art allowedus to select and implement an original strategy whose driving force is the solvent-induced assembly, i.e. based onthe stickiness of polystyrene (PS) macromolecules when they are subjected to a mixture of good and bad solvents.We investigated the assembly into clusters, chains or monolayers of one-patch, two-patch or three-patch silicananoparticles (NPs), respectively, the patches being PS macromolecules grafted at specific positions on theirsurface. One-patch silica NPs with controllable patch-to-particle size ratio were successfully synthesised throughphase separation and site-specific silica coating. Their assembly was performed in DMF/ethanol binary mixtures.The effect of the solvent quality, centrifugation force, particle concentration, incubation time and patch-to-size ratiowas investigated and discussed. The strategy was spread to obtain gold-coated clusters. The two-patch silica NPswere prepared through a seed-growth emulsion polymerisation of styrene and the patch-to-particle size ratio wasadjusted through the extent of the silica core regrowth. The chaining of the NPs was efficiently achieved in theTHF/NaCl aqueous solution mixtures by varying the NaCl concentration, solvent quality, incubation time, NPsconcentration and patch-to-particle size ratio. We showed that the kinetics of the chaining process is characteristicof a reaction-controlled step-growth polymerisation. Strategies to mimic homopolymers, random copolymers, blockcopolymers and branched polymers were implemented by using one-patch NPs, two-patch NPs with different sizes/surface chemical functions and/or three-patch NPs as building units. The three-patch silica NPs were obtainedthrough the same synthetic pathway than two-patch ones. For assembling them in honeycomb-like 2-D structures,we used the Langmuir technique.and we studied the influence of different experimental parameters. THF vapourannealing was implemented to reinforce mechanically the assembly but without significative effect on the packingdensity
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Yammine, Elham. "Synthèse de nanoparticules de latex de polystyrène à patchs magnétiques." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0397.
Повний текст джерелаАнотація:
Les particules à patchs magnétiques ont pris une importance toute particulière dans l’étude des assemblages vers de nouvelles structures colloïdales. L’état de l’art nous a montré que la majorité des systèmes synthétisés et étudiés concerne des particules à un seul patch magnétique limitant ainsi les possibilités de structures accessibles par assemblage. Notre objectif s’est donc centré sur l’obtention de nanoparticules sphériques de polystyrène (PS) porteuses de plusieurs nanoparticules superparamagnétiques à leur périphérie. La voie multi-étapes retenue a consisté à préparer par polymérisation en émulsion ensemencée des particules Janus magnétiques (MJPs) présentant un nodule de PS qui a ensuite été rendu « collant » dans un mélange de bon/mauvais solvant pour fusionner avec celui d’un nombre limité de particules similaires. Pour servir de patchs magnétiques d’environ 100 nm, nous avons préparé des supraparticules colloïdales de nanoparticules d’oxyde de fer superparamagnétiques par un procédé incluant des étapes d’évaporation d’une phase émulsifiée, de consolidation par la silice et de resserrement de la distribution de taille par purification. Les paramètres optimaux de la polymérisation en émulsion ensemencée (composition du mélange de tensioactifs, nature et taux de greffage de l’agent de couplage) et de l’assemblage (nature et fraction du bon solvant, concentration particulaire, température et durée d’incubation) ont été préalablement déterminés avec des nanoparticules-modèles de silice présentant un diamètre et un état de surface similaires. L’application de ces conditions aux MJPs s’est avérée plus compliquée que prévue notamment en raison de la faible quantité de supraparticules disponible et cela a notamment conduit à définir de nouvelles conditions de polymérisation en émulsion ensemencée. Finalement, des lots de nanoparticules de latex à deux ou trois patchs magnétiques ont été obtenus, mais nécessiteront des étapes de purification avant d’envisager des études d’assemblage sous champ magnétiqueMagnetic patchy particles are of great interest for assembly into novel colloidal structures. The state of the art showed us that the vast majority of synthesized and studied systems concerns particles with a single magnetic patch, thus limiting the structures accessible by particles assembly. Therefore, the main goal of the present study was to develop spherical polystyrene (PS) nanoparticles with two or many superparamagnetic nanoparticles on their surface. Our multistep process involved first the fabrication of Magnetic Janus particles (MJPs) by seeded-growth emulsion polymerization and subsequent incubation in suitable mixtures of good and bad solvents to make their polystyrene lobe “sticky”. MJPs are then ready to coalesce into self-assembled structures with small aggregation numbers. In order to obtain magnetic patches with a size range of 100 nm, we prepared colloidal supraparticles highly loaded with superparamagnetic iron oxide nanoparticles through a multistep procedure, including evaporation-induced emulsion, silica coating and purification, leading to a narrowing of the size distribution. The optimal parameters of the seeded-growth emulsion polymerization (surfactant mixture composition, coupling agent type, surface grafting density) and of the assembly (solvent quality, good solvent content, particle concentration, temperature and incubation time) were previously determined with silica nanoparticles as models with similar particle diameter as well as surface chemistry. We demonstrated that under the same conditions MJPs synthesis became trickier, mainly because of the small amount of available supraparticules. This led us to implement new seeded-growth emulsion polymerization conditions. Finally, batches of latex nanoparticles with two or three magnetic patches were obtained, but required further purification steps before investigating their assembly behavior under magnetic field
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Huber, Florian M. [Verfasser]. "Impact of kinetics and flow path heterogeneity on nanoparticle/radionuclide migration / Florian Mathias Huber." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1026695147/34.
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Mélanie, Ferrié. "Design de particules plasmoniques pour le contrôle de l'absorption et de l'émission de lumière." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2011. http://tel.archives-ouvertes.fr/tel-00676707.
Повний текст джерелаАнотація:
Au cours ce travail, nous nous sommes intéressés au design de particules plasmoniques pour le contrôle de l'absorption et de l'émission de lumière. Notre stratégie a été de synthétiser des nanoparticules de type coeur@écorce composées d'un coeur d'or et d'une écorce diélectrique de silice contenant des molécules organiques fluorescentes. Nous avons fait varier la distance entre ces dernières et le coeur afin de moduler l'intensité de leur couplage avec les plasmons du métal et d'ainsi contrôler les propriétés optiques des nanoparticules. Nous nous sommes aussi intéressés à l'assemblage de ces nanoparticules sous la forme de supra-particules ou de réseaux bidimensionnels organisés. L'étude des propriétés optiques de ces nouveaux matériaux a permis de mettre en évidence une forte exaltation de l'intensité de fluorescence des particules coeur@écorce quand celles-ci sont confinées entre deux nappes métalliques, ce qui correspond à un mode de cavité fort. Nous avons également travaillé sur la synthèse de particules composées d'un coeur de silice et soit d'une écorce d'or présentant des patchs " vierges ", soit d'une écorce de dioxyde de titane comportant des patchs recouverts de nanoparticules d'or.
Книги з теми "Patchy nanoparticles"
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Mehraeen, Shafigh, ed. Self-Assembly of Nanostructures and Patchy Nanoparticles. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.80196.
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Mehraeen, Shafigh. Self-Assembly of Nanostructures and Patchy Nanoparticles. IntechOpen, 2020.
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Fu, Huaxiang. Unusual properties of nanoscale ferroelectrics. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533053.013.19.
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This article describes the unusual properties of nanoscale ferroelectrics (FE), including widely tunable polarization and improved properties in strained ferroelectric thin films; polarization enhancement in superlattices; polarization saturation in ferroelectric thin films under very large inplane strains; occurrence of ferroelectric phase transitions in one-dimensional wires; existence of the toroidal structural phase in ferroelectric nanoparticles; and the symmetry-broken phase-transition path when one transforms a vortex phase into a polarization phase. The article first considers some of the critical questions on low-dimensional ferroelectricity before discussing the theoretical approaches used to determine the properties of ferroelectric nanostructures. It also looks at 2D ferroelectric structures such as surfaces, superlattices and thin films, along with 1D ferroelectric nanowires and ferroelectric nanoparticles.
Частини книг з теми "Patchy nanoparticles"
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Hamblin, Michael R. "Molecular and Cellular Mechanisms of Water-Filtered IR." In Water-filtered Infrared A (wIRA) Irradiation, 273–84. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92880-3_23.
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AbstractWater-filtered infrared A (wIRA) has been used to produce tissue hyperthermia to treat cancer, but also to treat a variety of other conditions, such as wound healing, pain, and inflammation. While the mechanism of anti-cancer hyperthermia is well-established, the mechanism of wIRA to promote healing and pain reduction is less clear. In this chapter, I will cover the use of photobiomodulation to treat several conditions characterized by mitochondrial dysfunction. Next the role of heat-sensitive transient receptor potential (TRP) ion channels is discussed, with regard to nitric oxide production and infrared neural stimulation. Then the use of infrared emitting bioceramic nanoparticles embedded in garments or patches, which are powered solely by body heat to promote healing and reduce pain and inflammation is discussed. The conclusion is that wIRA can activate heat-sensitive TRP channels, possibly mediated by energy absorption by nanostructured water clusters, leading to many of the observed therapeutic benefits.
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Zhang, Xiaochen, and Zhuo Yang. "Using the Whole Cell Patch Clamp Technique to Study the Effect of Nanoparticles in Hippocampal Neurons." In Neuromethods, 187–202. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7584-6_12.
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Kim, Ahyoung, Lehan Yao, Falon Kalutantirige, Shan Zhou, and Qian Chen. "Patchy Nanoparticle Synthesis and Self-Assembly." In Self-Assembly of Nanostructures and Patchy Nanoparticles. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93374.
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Biological building blocks (i.e., proteins) are encoded with the information of target structure into the chemical and morphological patches, guiding their assembly into the levels of functional structures that are crucial for living organisms. Learning from nature, researchers have been attracted to the artificial analogues, “patchy particles,” which have controlled geometries of patches that serve as directional bonding sites. However, unlike the abundant studies of micron-scale patchy particles, which demonstrated complex assembly structures and unique behaviors attributed to the patches, research on patchy nanoparticles (NPs) has remained challenging. In the present chapter, we discuss the recent understandings on patchy NP design and synthesis strategies, and physical principles of their assembly behaviors, which are the main factors to program patchy NP self-assembly into target structures that cannot be achieved by conventional non-patched NPs. We further summarize the self-assembly of patchy NPs under external fields, in simulation, and in kinetically controlled assembly pathways, to show the structural richness patchy NPs bring. The patchy NP assembly is novel by their structures as well as the multicomponent features, and thus exhibits unique optical, chemical, and mechanical properties, potentially aiding applications in catalysts, photonic crystals, and metamaterials as well as fundamental nanoscience.
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Ilnytskyi, Jaroslav. "Self-Assembly of Nanoparticles Decorated by Liquid Crystalline Groups: Computer Simulations." In Self-Assembly of Nanostructures and Patchy Nanoparticles. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.89682.
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We present the results of the computer simulations for the self-assembly of decorated nanoparticles. The models are rather generic and comprise a central core and a shell of ligands containing terminal liquid crystalline group, including the case of the azobenzene chromophores. The simulations are performed using the coarse-grained molecular dynamics with the effective soft-core interparticle interaction potentials obtained from the atomistic simulations. The discussion is centred around the set of the self-assembled morphologies in a melt of 100–200 of such decorated nanoparticles obtained upon the change of the temperature, surface density of ligands, the type of the terminal group attachment, as well as the prediction of the possibility of photo-assisted self-assembly of the nanoparticles decorated by the azobenzene chromophores.
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Xiong, Zushuang, Lanhai Lai, and Tianfeng Chen. "Self-Assembled Copper Polypyridyl Supramolecular Metallopolymer Achieving Enhanced Anticancer Efficacy." In Self-Assembly of Nanostructures and Patchy Nanoparticles. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92708.
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Metallopolymers, a combination of organic polymers and metal center, contain metal atoms in repeating monomers can change its dynamic and thermodynamic properties through the directionality of coordination bonds and chemical tailoring of ligands. In the past decade, self-assembled functional supramolecular metallopolymers have aroused a surge of research interest, and have demonstrated application potential in cancer therapy. In this chapter, we have summarized the progress in the rational design of biological application of different metallopolymers. Especially, a copper polypyridyl complex was found be able to self-assemble into a supramolecular metallopolymer driven by the intermolecular interactions, which could enhance the uptake in cancer cells through endocytosis, thus effectively inhibit tumor growth in vivo without damage to the major organs. This study may provide a good example to use self-assembled metallopolymer to achieve enhanced anticancer efficacy.
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Giang Le, Thi. "Self-Assembly of GeMn Nanocolumns in GeMn Thin Films." In Self-Assembly of Nanostructures and Patchy Nanoparticles. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92709.
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This chapter presents the results of growing GeMn nanocolumns on Ge(001) substrates by means of molecular beam epitaxy (MBE). The samples have been prepared by co-depositing Ge and Mn at growth temperature of 130°C and Mn at concentration of ~6% to ensure the reproduction of GeMn nanocolumns. Based on the observation of changes in reflection high-energy electron diffraction (RHEED) patterns during nanocolumn growth, surface signals of GeMn nanocolumn formation have been identified. Structural analysis using transmission electron microscopy (TEM) show the self-assembled nanocolumns with core-shell structure extend through the whole thickness of the GeMn layer. Most of nanocolumns are oriented perpendicular to the interface along the growth direction. The nanocolumn size has been determined to be about 5–8 nm in diameter and a maximum height of 80 nm. A phenomenological model has been proposed to explain the driving force for self-assembly and growth mechanisms of GeMn nanocolumns. The in-plane or lateral Mn diffusion/segregation is driven by a low solubility of Mn in Ge while the driving force of Mn vertical segregation is induced by the surfactant effect along the [001] direction.
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Mehraeen, Shafigh. "Introductory Chapter: Self-Assembly of Nanostructures." In Self-Assembly of Nanostructures and Patchy Nanoparticles. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94014.
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Kumar, Sudheer, Sukhila Krishnan, Sushanta Kumar Samal, Smita Mohanty, and Sanjay Kumar Nayak. "Polymer Nanocomposites Coating for Anticorrosion Application." In Polymer Nanocomposites for Advanced Engineering and Military Applications, 254–94. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7838-3.ch009.
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Corrosion is the foremost reason for the deterioration of metallic components used in harsh environments and hence research on the development of an innovative protective system with admirable performance has become a subject of leading importance. Currently, chromates free organic or the polymer coatings on the metal substrate bestow an efficient barrier amongst the metal and inhibit corrosion and save the environment. Researchers have involved in the development of polymer coating containing nanoparticles because reinforcement of nanoparticles decreases the porosity and provides a zig-zag diffusion path which in turn forms barrier layer on the metal surface to protect the metal from the harmful corrosive species. This present chapter deliberates the application of polymer-based nanocomposite coating to mitigate the corrosion of metals against harsh environment. This chapter covers the utilization of carbon-based nanoparticles, inorganic nanoparticle, conductive polymer, self-heling polymer, etc., and could shows a new insight to for anti-corrosive metal surface protective coating.
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Kumar, Sudheer, Sukhila Krishnan, Sushanta Kumar Samal, Smita Mohanty, and Sanjay Kumar Nayak. "Polymer Nanocomposites Coating for Anticorrosion Application." In Research Anthology on Synthesis, Characterization, and Applications of Nanomaterials, 1093–134. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8591-7.ch045.
Повний текст джерелаАнотація:
Corrosion is the foremost reason for the deterioration of metallic components used in harsh environments and hence research on the development of an innovative protective system with admirable performance has become a subject of leading importance. Currently, chromates free organic or the polymer coatings on the metal substrate bestow an efficient barrier amongst the metal and inhibit corrosion and save the environment. Researchers have involved in the development of polymer coating containing nanoparticles because reinforcement of nanoparticles decreases the porosity and provides a zig-zag diffusion path which in turn forms barrier layer on the metal surface to protect the metal from the harmful corrosive species. This present chapter deliberates the application of polymer-based nanocomposite coating to mitigate the corrosion of metals against harsh environment. This chapter covers the utilization of carbon-based nanoparticles, inorganic nanoparticle, conductive polymer, self-heling polymer, etc., and could shows a new insight to for anti-corrosive metal surface protective coating.
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Jasrotia, R. "Spinel Ferrite Based Nanomaterials for Water Remediation Application." In Materials Research Foundations, 218–45. Materials Research Forum LLC, 2021. http://dx.doi.org/10.21741/9781644901595-6.
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The decreasing levels of consumable water on earth have been a serious issue and this issue makes the researchers and scientists develop new technologies for the purification of polluted water. Several reports have been carried on wastewater remediation by utilizing spinel ferrite-based nanoparticles and their composites. The spinel ferrites-based nanoparticles utilized for wastewater treatment was cost effective, chemically stable, easily retrieved and reusable. The present work addresses the various fabrication techniques for the preparation of spinel ferrite-based nanoparticles and their utilization for the removal of organic and inorganic pollutants through the adsorption paths.
Тези доповідей конференцій з теми "Patchy nanoparticles"
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Dao, Thang Duy, Ha Lien Thi Nghiem, Kai Chen, and Tadaaki Nagao. "Ensemble of gold-patchy nanoparticles with multiple hot-spots for plasmon-enhanced vibrational spectroscopy." In SPIE Nanoscience + Engineering, edited by Akhlesh Lakhtakia, Tom G. Mackay, and Motofumi Suzuki. SPIE, 2016. http://dx.doi.org/10.1117/12.2237864.
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Eapen, Jacob. "Thermal Conduction Mechanism in Nanofluids, Solid Composites and Liquid Mixtures." In ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88236.
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Analysis of Maxwell’s mean-field (or effective-medium) theory reveals two limiting bounds — an upper and a lower bound — for thermal conductivity in binary composite systems. The lower and the upper bounds correspond to continuous conduction paths through the base medium and the dispersed medium, respectively (assuming that the dispersed medium has a higher thermal conductivity). Extensive comparisons to experimental data show that most of the reported thermal conductivity data on nanofluids, solid composites and liquid mixtures fall between the limiting Maxwell bounds. For a nanofluid, this indicates that the effective thermal conductivity is largely dependent on the geometrical configuration and the connectivity of the dispersed nanoparticle phase. The lower bound corresponds to a colloidal configuration of well-dispersed nanoparticles with the continuous conduction path provided by the base medium while the upper bound represents a linear, fractal-like nanoparticle arrangement with the continuous conduction path provided by the nanoparticles.
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Feng, Zhi-Gang, Yusheng Feng, and Maria Andersson. "Shape Effects on the Drag Force and Motion of Nano and Micro Particles in Low Reynolds Number Flows." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89469.
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Particulate flows are commonly found in a variety of applications. For example, nanoparticles have been used in targeted drug delivery systems and improving heat transfer in nanofluids. Crucial to the development of technologies that incorporate nanoparticles is to understand the effect of a nanoparticle’s shape on its motion. The effect of shape on nanoparticles used in drug delivery, in particular, is a very active area of experimental investigation. Also, the determination of the coefficients of hydrodynamic forces or drag forces on nanoparticles of different shapes is crucial in designing effective nanoparticle-mediated therapies. In this study we present a resolved discrete particle method (RDPM), which is also called the Direct Numerical Simulation (DNS), to investigate the effect of shape on drag force in a vicious fluid. Three different shapes of particles are studied: a sphere, a probate ellipsoid, and an oblate ellipsoid. These particles have the same volume and are placed in contact with the bottom wall in simple shear flows. Their drag forces are computed numerically; it is found that the particle shape has a significant effect on the drag forces. In the case of a spherical particle, our results agree very well with the analytical results found in the literature. The motion of three particles of the same volume but different shape in a simple shear flows are also simulated. It shows that different particle shapes cause particles to experience different hydrodynamics forces, leading them to different velocities and paths.
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Prasher, Ravi. "Beating the Thermal Conductivity of Air Using Packed Nanoparticle Bed." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14931.
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Thermal conductivity of packed bed of nanoparticles is calculated in this paper. Results show that effective thermal conductivity of nanoparticle bed can be very low. Thermal conductivity of the nanoparticle bed can be smaller than the thermal conductivity of air. Thermal conductivity depends on pressure, surface energy of the nanoparticle, and phonon mean free path.
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Kim, Seontae, Hyungmo Kim, Hyung Dae Kim, Ho Seon Ahn, Moo Hwan Kim, Joonwon Kim, and Goon-Cherl Park. "Experimental Investigation of Critical Heat Flux Enhancement by Micro/Nanoscale Surface Modification in Pool Boiling." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62289.
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Nanofluids, which contain uniformly and stably dispersed nanoparticles, exhibit an abnormal enhancement of the critical heat flux (CHF) when used as a working fluid in pool boiling. It has recently been demonstrated that optimal CHF enhancement in nanofluids is attained by the significant deposition of nanoparticles on the heater surface during pool boiling. The surface deposition of oxidized metal nanoparticles significantly enhances the wettability, and fractal micro/nanostructures formed by nanoparticle deposition induce liquid suction due to capillary wicking. It is supposed that the superior wettability and capillary wicking of the nanoparticle-fouled surface enhances CHF by promoting the dry patches to be effectively rewetted during the boiling process. In this regard, the excellent CHF performance of the nanoparticle-deposited surface can be reproduced using artificial structures via innovative surface-modification methods that yield good wettability and capillarity. To accomplish this goal, we plan to design and fabricate various artificial micro/nano-structured surfaces with good surface wettability and capillarity, and investigate their CHF performance. In the present study, we examined experimentally the CHF performances of a series of surface-modified samples (plane, micro-structured, nano-structured, and micro/nano structured surfaces). Pool boiling heat transfer of pure water on sample surfaces was investigated under atmospheric conditions. The CHF increase due to artificial surface modification is discussed based on solid-liquid interfacial parameters (static contact angle, roughness) that are closely related to CHF phenomenon in pool boiling.
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Zhang, Wenyang, Muhammad P. Jahan, and Ajay P. Malshe. "Chemical Understanding of Friction Polymer Based Tribo-Chemical Films Derived From Nanolubricant." In ASME/STLE 2012 International Joint Tribology Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ijtc2012-61119.
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MoS2 multi-component nanolubrication system showed significant friction and wear reduction (more than 30% in friction reduction and 50% in wear reduction) in sliding steel surfaces, especially under mixed and boundary lubrication conditions [1–3]. It is believed that the formation of tribofilms in MoS2 multi-component nanolubrication system under different lubrication regimes is the primary reason for reduced friction and wear. To investigate the in-depth science of the tribo-chemical interface formed by MoS2 multicomponent nanolubrication system, it is necessary to study the chemical states of tribofilm during its evolution (generation ↔ regeneration) process at tribo-interfaces. Tribofilms from various lubrication regimes were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), Raman microscope, and X-ray photoelectron spectroscopy (XPS) techniques to study the morphology, chemical composition, elemental distribution, and chemical bonding of tribo-chemical surface, respectively. Besides the evolution process, the characterization of tribofilms also reveals the possibility of forming new meta-stable phases (chemical compounds) after tribological testing. Patchy tribofilms and progressive tribofilms have been observed from the SEM analysis and the EDX results showed existence of Mo-S-P as the composition of tribo-chemical films. The Raman spectroscopy analysis of tribofilms showed significant difference (such as formation of poly-molybdates) in chemical information of nanolubricants and tribofilms, which is an indication of the formation of friction polymer [4–5]. Additionally, phosphates and oxides, acting as components of surface protecting layer of tribofilms, have been found on surface by XPS technique. Moreover, MoS2 nanoparticles are found to navigate into surface asperities to protect the contacting surfaces. The results (information about the chemical states of the tribofilm) obtained from different characterization techniques can be used to explain the mechanism of friction and wear reduction associated with MoS2 multi-component nanolubrication system that has been reported in the literature.
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Szczech, John B., Constantine M. Megaridis, Jie Zhang, and Daniel Gamota. "Ink Jet Processing of Metallic Nanoparticle Suspensions for Electronic Circuitry Fabrication." In ASME 2003 1st International Conference on Microchannels and Minichannels. ASMEDC, 2003. http://dx.doi.org/10.1115/icmm2003-1104.
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A novel approach in creating circuit electrodes with features as fine as 100 μm is demonstrated using a single 38 μm diameter orifice, piezoelectrically driven print head to deposit metallic nanoparticle suspensions. The suspensions consist of gold particles of ∼20 nm diameter suspended in toluene solvent. The amount of gold nanoparticles present in the suspension is 30% wt. Inductor and capacitor electrode patterns are deposited onto a glass substrate and thermally processed at 300°C for 15 minutes to drive off the solvent and allow the nanoparticles to sinter, thereby yielding a conductive path with a resistivity of O(10−7) Ω m.
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Hafiz, J., R. Mukherjee, X. Wang, P. H. McMurry, J. V. R. Heberlein, and S. L. Girshick. "Hypersonic Plasma Particle Deposition – A Hybrid between Plasma Spraying and Vapor Deposition." In ITSC2006, edited by B. R. Marple, M. M. Hyland, Y. C. Lau, R. S. Lima, and J. Voyer. ASM International, 2006. http://dx.doi.org/10.31399/asm.cp.itsc2006p1323.
Повний текст джерелаАнотація:
Abstract In the hypersonic plasma particle deposition process, vapor phase reactants are injected into a plasma and rapidly quenched in a supersonic nozzle, leading to nucleation of nanosize particles. These particles impact a substrate at high velocity, forming a coating with grain sizes of 10 to 40 nm. As previously reported, coatings of a variety of materials have been obtained, including silicon, silicon carbide, titanium carbide and nitride, and composites of these, all deposited at very high rates. Recent studies have shown that slight modifications of the process can result in nanosize structures consisting of single crystal silicon nanowires covered with nanoparticles. These nanowires are believed to grow in a vapor deposition process, catalyzed by the presence of titanium in the underlying nanoparticle film. However, simultaneously nanoparticles are nucleated in the nozzle and deposited on the nanowires, leading to structures that are the result of a plasma CVD process combined with a nanoparticle spray process. The combination of these two process paths opens new dimensions in nanophase materials processing.
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Felix Servin, Jesus Manuel, Hala A. Al-Sadeg, and Amr Abdel-Fattah. "Photoacoustic Nanotracers for Subsurface Applications: Opportunities and Challenges." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206316-ms.
Повний текст джерелаАнотація:
Abstract Tracers are practical tools to gather information about the subsurface fluid flow in hydrocarbon reservoirs. Typical interwell tracer tests involve injecting and producing tracers from multiple wells to evaluate important parameters such as connectivity, flow paths, fluid-fluid and fluid-rock interactions, and reservoir heterogeneity, among others. The upcoming of nanotechnology enables the development of novel nanoparticle-based tracers to overcome many of the challenges faced by conventional tracers. Among the advantages of nanoparticle-based tracers is the capability to functionalize their surface to yield stability and transportability through the subsurface. In addition, nanoparticles can be engineered to respond to a wide variety of stimuli, including light. The photoacoustic effect is the formation of sound waves following light absorption in a material sample. The medical community has successfully employed photoacoustic nanotracers as contrast agents for photoacoustic tomography imaging. We propose that properly engineered photoacoustic nanoparticles can be used as tracers in oil reservoirs. Our analysis begins by investigating the parameters controlling the conversion of light to acoustic waves, and strategies to optimize such parameters. Next, we analyze different kind of nanoparticles that we deem potential candidates for our subsurface operations. Then, we briefly discuss the excitation sources and make a comparison between continuous wave and pulsed sources. We finish by discussing the research gaps and challenges that must be addressed to incorporate these agents into our operations. At the time of this writing, no other study investigating the feasibility of using photoacoustic nanoparticles for tracer applications was found. Our work paves the way for a new class of passive tracers for oil reservoirs. Photoacoustic nanotracers are easy to detect and quantify and are therefore suitable for continuous in-line monitoring, contributing to the ongoing real-time data efforts in the oil and gas industry.
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Tian, Weixue, and Ronggui Yang. "Thermal Conductivity of High Contrast Nanoparticle Composites." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32120.
Повний текст джерелаАнотація:
In this paper, we investigated the thermal conductivity of three-dimensional nanocomposites composed of randomly distributed nanoparticles with large thermal conductivity differences in the constituents. Nanoparticles in composite materials fabricated by processes such as hot press or spark plasma sintering tend to be randomly distributed. For composites made of particles with high thermal conductivity contrast ratio, percolation theory predicts the existence of a continuous phase of high thermal conductivity material when its volumetric concentration reaches beyond the percolation threshold. Such a continuous phase can provide a low resistance pathway for phonon transport in the nanocomposites. Therefore, the thermal conductivity of the composites is expected to increase significantly with increasing concentration of the high thermal conductivity nanoparticles. However, when the characteristic size of the nanoparticles is comparable or smaller than the phonon mean free path, the interface between two materials causes phonon scattering and significant thermal resistance in the highly conductive phonon pathway. Such an additional thermal resistance can reduce the magnitude of the thermal conductivity improvement in the nanocomposites. In this study, the Monte Carlo simulation was employed to generate the nanoparticle random distribution and to simulate phonon transport in the nanocomposites. The effects of particle size, thermal conductivity contrast and interface characteristic on thermal conductivity of the nanocomposites are discussed.
Звіти організацій з теми "Patchy nanoparticles"
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Choudhary, Ruplal, Victor Rodov, Punit Kohli, Elena Poverenov, John Haddock, and Moshe Shemesh. Antimicrobial functionalized nanoparticles for enhancing food safety and quality. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598156.bard.
Повний текст джерелаАнотація:
Original objectives The general goal of the project was to utilize the bactericidal potential of curcumin- functionalizednanostructures (CFN) for reinforcement of food safety by developing active antimicrobial food-contact surfaces. In order to reach the goal, the following secondary tasks were pursued: (a) further enhancement of the CFN activity based on understanding their mode of action; (b) preparing efficient antimicrobial surfaces, investigating and optimizing their performance; (c) testing the efficacy of the antimicrobial surfaces in real food trials. Background to the topic The project dealt with reducing microbial food spoilage and safety hazards. Cross-contamination through food-contact surfaces is one of the major safety concerns, aggravated by bacterial biofilm formation. The project implemented nanotech methods to develop novel antimicrobial food-contact materials based on natural compounds. Food-grade phenylpropanoidcurcumin was chosen as the most promising active principle for this research. Major conclusions, solutions, achievements In agreement with the original plan, the following research tasks were performed. Optimization of particles structure and composition. Three types of curcumin-functionalizednanostructures were developed and tested: liposome-type polydiacetylenenanovesicles, surface- stabilized nanoparticles and methyl-β-cyclodextrin inclusion complexes (MBCD). The three types had similar minimal inhibitory concentration but different mode of action. Nanovesicles and inclusion complexes were bactericidal while the nanoparticlesbacteriostatic. The difference might be due to different paths of curcumin penetration into bacterial cell. Enhancing the antimicrobial efficacy of CFN by photosensitization. Light exposure strengthened the bactericidal efficacy of curcumin-MBCD inclusion complexes approximately three-fold and enhanced the bacterial death on curcumin-coated plastic surfaces. Investigating the mode of action of CFN. Toxicoproteomic study revealed oxidative stress in curcumin-treated cells of E. coli. In the dark, this effect was alleviated by cellular adaptive responses. Under light, the enhanced ROS burst overrode the cellular adaptive mechanisms, disrupted the iron metabolism and synthesis of Fe-S clusters, eventually leading to cell death. Developing industrially-feasible methods of binding CFN to food-contact surfaces. CFN binding methods were developed for various substrates: covalent binding (binding nanovesicles to glass, plastic and metal), sonochemical impregnation (binding nanoparticles to plastics) and electrostatic layer-by-layer coating (binding inclusion complexes to glass and plastics). Investigating the performance of CFN-coated surfaces. Flexible and rigid plastic materials and glass coated with CFN demonstrated bactericidal activity towards Gram-negative (E. coli) and Gram-positive (Bac. cereus) bacteria. In addition, CFN-impregnated plastic material inhibited bacterial attachment and biofilm development. Testing the efficacy of CFN in food preservation trials. Efficient cold pasteurization of tender coconut water inoculated with E. coli and Listeriamonocytogeneswas performed by circulation through a column filled with CFN-coated glass beads. Combination of curcumin coating with blue light prevented bacterial cross contamination of fresh-cut melons through plastic surfaces contaminated with E. coli or Bac. licheniformis. Furthermore, coating of strawberries with CFN reduced fruit spoilage during simulated transportation extending the shelf life by 2-3 days. Implications, both scientific and agricultural BARD Report - Project4680 Page 2 of 17 Antimicrobial food-contact nanomaterials based on natural active principles will preserve food quality and ensure safety. Understanding mode of antimicrobial action of curcumin will allow enhancing its dark efficacy, e.g. by targeting the microbial cellular adaptation mechanisms.