Artigos de revistas: "Colloidal agglomeration"

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Osaci, Mihaela, e Matteo Cacciola. "Influence of the magnetic nanoparticle coating on the magnetic relaxation time". Beilstein Journal of Nanotechnology 11 (12 de agosto de 2020): 1207–16. http://dx.doi.org/10.3762/bjnano.11.105.

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Colloidal systems consisting of monodomain superparamagnetic nanoparticles have been used in biomedical applications, such as the hyperthermia treatment for cancer. In this type of colloid, called a nanofluid, the nanoparticles tend to agglomeration. It has been shown experimentally that the nanoparticle coating plays an important role in the nanoparticle dispersion stability and biocompatibility. However, theoretical studies in this field are lacking. In addition, the ways in which the nanoparticle coating influences the magnetic properties of the nanoparticles are not yet understood. In order to fill in this gap, this study presents a numerical simulation model that elucidates how the nanoparticle coating affects the nanoparticle agglomeration tendency as well as the effective magnetic relaxation time of the system. To simulate the self-organization of the colloidal nanoparticles, a stochastic Langevin dynamics method was applied based on the effective Verlet-type algorithm. The Néel magnetic relaxation time was obtained via the Coffey method in an oblique magnetic field, adapted to the local magnetic field on a nanoparticle.

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Maillette, Sébastien, Caroline Peyrot, Tapas Purkait, Muhammad Iqbal, Jonathan G. C. Veinot e Kevin J. Wilkinson. "Heteroagglomeration of nanosilver with colloidal SiO2 and clay". Environmental Chemistry 14, n.º 1 (2017): 1. http://dx.doi.org/10.1071/en16070.

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Environmental contextThe fate of nanomaterials in the environment is related to their colloidal stability. Although numerous studies have examined their homoagglomeration, their low concentration and the presence of high concentrations of natural particles implies that heteroagglomeration rather than homoagglomeration is likely to occur under natural conditions. In this paper, two state-of-the art analytical techniques were used to identify the conditions under which nanosilver was most likely to form heteroagglomerates in natural waters. AbstractThe environmental risk of nanomaterials will depend on their persistence, mobility, toxicity and bioaccumulation. Each of these parameters is related to their fate (especially dissolution, agglomeration). The goal of this paper was to understand the heteroagglomeration of silver nanoparticles in natural waters. Two small silver nanoparticles (nAg, ~3nm; polyacrylic acid- and citrate-stabilised) were covalently labelled with a fluorescent dye and then mixed with colloidal silicon oxides (SiO2, ~18.5nm) or clays (~550nm SWy-2 montmorillonite). Homo- and heteroagglomeration of the nAg were first studied in controlled synthetic waters that were representative of natural fresh waters (50μg Ag L–1; pH 7.0; ionic strength 10–7 to 10–1 M Ca) by following the sizes of the nAg by fluorescence correlation spectroscopy. The polyacrylic acid-coated nanosilver was extremely stable under all conditions, including in the presence of other colloids and at high ionic strengths. However, the citrate-coated nanosilver formed heteroaggregates in presence of both colloidal SiO2 and clay particles. Nanoparticle surface properties appeared to play a key role in controlling the physicochemical stability of the nAg. For example, the polyacrylic acid stabilized nAg-remained extremely stable in the water column, even under conditions for which surrounding colloidal particles were agglomerating. Finally, enhanced dark-field microscopy was then used to further characterise the heteroagglomeration of a citrate-coated nAg with suspensions of colloidal clay, colloidal SiO2 or natural (river) water.

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Marć, Maciej, Andrzej Drzewiński, Wiktor W. Wolak, Lidia Najder-Kozdrowska e Mirosław R. Dudek. "Filtration of Nanoparticle Agglomerates in Aqueous Colloidal Suspensions Exposed to an External Radio-Frequency Magnetic Field". Nanomaterials 11, n.º 7 (1 de julho de 2021): 1737. http://dx.doi.org/10.3390/nano11071737.

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The study investigated the phenomenon of the fast aggregation of single-domain magnetic iron oxide nanoparticles in stable aqueous colloidal suspensions due to the presence of a radio-frequency (RF) magnetic field. Single-domain nanoparticles have specific magnetic properties, especially the unique property of absorbing the energy of such a field and releasing it in the form of heat. The localized heating causes the colloid to become unstable, leading to faster agglomeration of nanoparticles and, consequently, to rapid sedimentation. It has been shown that the destabilization of a stable magnetic nanoparticle colloid by the RF magnetic field can be used for the controlled filtration of larger agglomerates of the colloid solution. Two particular cases of stable colloidal suspensions were considered: a suspension of the bare nanoparticles in an alkaline solution and the silica-stabilized nanoparticles in a neutral solution. The obtained results are important primarily for biomedical applications and wastewater treatment.

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Solodova O.V., Sokolov A.E., Ivanova O.S., Volochaev M.N., Lapin I.N., Goncharova D.A. e Svetlichnyi V.A. "Magneto-optical properties of nanoparticle dispersions based on Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=-, obtained by pulse laser ablation in a liquid". Physics of the Solid State 64, n.º 14 (2022): 2334. http://dx.doi.org/10.21883/pss.2022.14.54331.147.

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The structure, optical and magneto-optical properties of colloidal solutions of iron oxide nanoparticles obtained by pulsed ablation in distilled water, both without additives and with various functional additives: gold-hydrochloric acid, silicon oxide, and polyvinylpyrrolidone, have been studied. It is shown that the main magnetic phase is magnetite Fe3O4. The size distribution of nanoparticles and the degree of their agglomeration depend on the additives. In the absence of the latter, a very wide of size distributions and strong agglomeration of particles are observed. The narrowest distribution curve with a maximum corresponding to ~7 nm and an almost complete absence of agglomeration are observed for particles synthesized in the presence of polyvinylpyrrolidone. The shape of the spectral dependence of magnetic circular dichroism, which generally corresponds to the spectrum of magnetite, undergoes some modifications for various additives, which is associated with defects in the distribution of iron ions between different positions in the crystal. Keywords: pulsed laser ablation, nanoparticles, colloidal solutions, magnetite, magnetic circular dichroism.

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Bernad, Sandor I., Vlad Socoliuc, Izabell Craciunescu, Rodica Turcu e Elena S. Bernad. "Field-Induced Agglomerations of Polyethylene-Glycol-Functionalized Nanoclusters: Rheological Behaviour and Optical Microscopy". Pharmaceutics 15, n.º 11 (10 de novembro de 2023): 2612. http://dx.doi.org/10.3390/pharmaceutics15112612.

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This research aims to investigate the agglomeration processes of magnetoresponsive functionalized nanocluster suspensions in a magnetic field, as well as how these structures impact the behaviour of these suspensions in biomedical applications. The synthesis, shape, colloidal stability, and magnetic characteristics of PEG-functionalized nanoclusters are described in this paper. Experiments using TEM, XPS, dynamic light scattering (DLS), VSM, and optical microscopy were performed to study chain-like agglomeration production and its influence on colloidal behaviour in physiologically relevant suspensions. The applied magnetic field aligns the magnetic moments of the nanoclusters. It provides an attraction between neighbouring particles, resulting in the formation of chains, linear aggregates, or agglomerates of clusters aligned along the applied field direction. Optical microscopy has been used to observe the creation of these aligned linear formations. The design of chain-like structures can cause considerable changes in the characteristics of ferrofluids, ranging from rheological differences to colloidal stability changes.

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Jia, Jun, e Fengyuan Sun. "Application of Polymer Nanocolloid Preparation in Stability Analysis of Motion Mechanics". Advances in Materials Science and Engineering 2022 (31 de agosto de 2022): 1–11. http://dx.doi.org/10.1155/2022/7260515.

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Nanomaterials are widely used in various fields because of their own advantages. When the particle size of the material is reduced to the nanometer level, it will lead to new characteristics of acoustic, optical, electrical, magnetic, and thermal properties. This will greatly enrich the research content of the material and is expected to get new uses. Therefore, the preparation technology of nanomaterials is one of the current research hotspots and has broad application prospects. At present, the most commonly used preparation techniques are hydrothermal method and sol-gel method, but not all crystals grow in a hydrothermal environment, so this paper adopts the sol-gel method for preparation. However, in the preparation of nanocolloids, agglomeration often occurs between colloidal nanoparticles. In order to avoid the agglomeration between particles, this paper adopts an appropriate method to disperse the particles. In order to further explore the stability of nanocolloids, the colloidal film material prepared by the cadmium sulfide (CdS) sol method was used as the research sample. It also proposes a sol preparation method incorporating ultrasonic waves and further discusses the kinetic characteristics. The research results show that the sedimentation velocity of 1 nm cadmium sulfide nanocolloids in water is 1.3 × 10−12 (m/s) prepared by colloid of cadmium sulfide.

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Cecil, Adam J., John E. Payne, Luke T. Hawtrey, Ben King, Gerold A. Willing e Stuart J. Williams. "Nonlinear Agglomeration of Bimodal Colloids under Microgravity". Gravitational and Space Research 10, n.º 1 (1 de janeiro de 2022): 1–9. http://dx.doi.org/10.2478/gsr-2022-0001.

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Abstract A study of like-charged, bimodal colloidal suspensions was conducted in microgravity aboard the International Space Station as part of NASA's Advanced Colloids Experiments-Heated-2 (ACE-H-2) experiments. Samples comprised of silsesquioxane microparticles (600 nm) and zirconia nanoparticles (5–15 nm) in 1.5 pH nitric acid were mixed and allowed to agglomerate over time while being imaged with NASA's Light Microscopy Module (LMM). The samples contained 1% of microparticles with varying concentrations of nanoparticles in 0.1%, 0.055%, and 0.01% by volume. Digital images were captured periodically by the LMM over 12 days. Image analysis, including cluster size and distribution, was performed in Python using the “Colloidspy” package. The study found that cluster size had increased over time in at least seven of nine samples, but two samples exhibited nonlinear growth rates, while others showed very slow growth with cluster sizes two orders of magnitude greater than the free microparticles. We hypothesize that all samples experienced nonlinear growth, but early transient effects after mixing were missed due to timing limitations in image acquisition. Transport limitations of clusters in these systems may have dominated agglomeration behavior in microgravity, despite the samples being thermodynamically unstable, but more study is required.

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Ip, Alexander H., Amirreza Kiani, Illan J. Kramer, Oleksandr Voznyy, Hamidreza F. Movahed, Larissa Levina, Michael M. Adachi, Sjoerd Hoogland e Edward H. Sargent. "Infrared Colloidal Quantum Dot PhotovoltaicsviaCoupling Enhancement and Agglomeration Suppression". ACS Nano 9, n.º 9 (19 de agosto de 2015): 8833–42. http://dx.doi.org/10.1021/acsnano.5b02164.

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Solaimany-Nazar, Ali Reza, e Hassan Rahimi. "Investigation on Agglomeration−Fragmentation Processes in Colloidal Asphaltene Suspensions". Energy & Fuels 23, n.º 2 (19 de fevereiro de 2009): 967–74. http://dx.doi.org/10.1021/ef800728h.

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Kim, Jin-Wook, e Timothy A. Kramer. "Improved models for fractal colloidal agglomeration: computationally efficient algorithms". Colloids and Surfaces A: Physicochemical and Engineering Aspects 253, n.º 1-3 (fevereiro de 2005): 33–49. http://dx.doi.org/10.1016/j.colsurfa.2004.10.101.

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Link, Julian, Bastian Strybny, Thibaut Divoux, Thomas Sowoidnich, Max Coenen, Stefan Gstöhl, Christian M. Schlepütz et al. "Mechanisms of thixotropy in cement suspensions considering influences from shear history and hydration". ce/papers 6, n.º 6 (dezembro de 2023): 698–704. http://dx.doi.org/10.1002/cepa.2810.

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AbstractThe rheological properties of fresh concrete are a direct function of the interaction behaviour of the granular inventory of the concrete (i.e., gravel, sand and cement) and especially of the colloidal fractions of cement. Under low shear stresses, agglomeration of colloidal particles is observed, while at high shear stresses, dispersion of these agglomerates occurs. Besides the agglomeration state, the formation of shear banding, zones with concentrated shear flow, is another controlling mechanism of the flow behaviour of cement suspensions. Rheological creep tests in this study are focused on investigating the influence of shear history and hydration process on thixotropy of cement suspension. In this paper, the meaning of the word thixotropy is slightly extended to additionally encompass rheological aging and hydration effects. Selected samples were analyzed by coupling a rheometer to synchrotron X‐ray tomography to gain insight into the shear‐induced microstructural changes during shear start‐up tests. The observations show heterogeneities in the velocity profile in the shear gap and the development of shear banding.

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Doblas, David, Thomas Kister, Marina Cano-Bonilla, Lola González-García e Tobias Kraus. "Colloidal Solubility and Agglomeration of Apolar Nanoparticles in Different Solvents". Nano Letters 19, n.º 8 (28 de junho de 2019): 5246–52. http://dx.doi.org/10.1021/acs.nanolett.9b01688.

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Ozaki, Masataka, Tamami Egami, Noriko Sugiyama e Egon Matijević. "Agglomeration in colloidal hematite dispersions due to weak magnetic interactions". Journal of Colloid and Interface Science 126, n.º 1 (novembro de 1988): 212–19. http://dx.doi.org/10.1016/0021-9797(88)90114-2.

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Barcenas, Mariana, Janna Douda e Yurko Duda. "Temperature dependence of the colloidal agglomeration inhibition: Computer simulation study". Journal of Chemical Physics 127, n.º 11 (21 de setembro de 2007): 114706. http://dx.doi.org/10.1063/1.2768519.

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Hu, Yang, Lingyun Liu, Fanfei Min, Mingxu Zhang e Shaoxian Song. "Hydrophobic agglomeration of colloidal kaolinite in aqueous suspensions with dodecylamine". Colloids and Surfaces A: Physicochemical and Engineering Aspects 434 (outubro de 2013): 281–86. http://dx.doi.org/10.1016/j.colsurfa.2013.05.074.

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Echeverría, Coro, e Carmen Mijangos. "A Way to Predict Gold Nanoparticles/Polymer Hybrid Microgel Agglomeration Based on Rheological Studies". Nanomaterials 9, n.º 10 (21 de outubro de 2019): 1499. http://dx.doi.org/10.3390/nano9101499.

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In this work, a detailed rheological study of hybrid poly(acrylamide-co-acrylic acid) P(AAm-co-AAc) aqueous microgel dispersions is performed. Our intention is to understand how the presence of gold nanoparticles, AuNP, embedded within the microgel matrix, affects the viscoelastic properties, the colloidal gel structure formation, and the structure recovery after cessation of the deformation of the aqueous microgel dispersions. Frequency sweep experiments confirmed that hybrid microgel dispersions present a gel-like behavior and that the presence of AuNP content within microgel matrix contributes to the elasticity of the microgel dispersions. Strain sweep test confirmed that hybrid microgels aqueous dispersion also form colloidal gel structures that break upon deformation but that can be recovered when the deformation decreases. The fractal analysis performed to hybrid microgels, by applying Shih et al. and Wu and Morbidelli’s scaling theories, evidenced that AuNP significantly affects the colloidal gel structure configuration ending up with the formation of agglomerates or microgel clusters with closer structures in comparison to the reference P(AAm-co-AAc) aqueous microgel dispersions.

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Barcenas, Mariana, e Yurko Duda. "Irreversible colloidal agglomeration in presence of associative inhibitors: Computer simulation study". Physics Letters A 365, n.º 5-6 (junho de 2007): 454–57. http://dx.doi.org/10.1016/j.physleta.2007.01.059.

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Солодова, О. В., А. Э. Соколов, О. С. Иванова, М. Н. Волочаев, И. Н. Лапин, Д. А. Гончарова e В. А. Светличный. "Магнитооптические свойства дисперсий наночастиц на основе Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=-, полученных методом импульсной лазерной абляции в жидкости". Физика твердого тела 63, n.º 12 (2021): 2061. http://dx.doi.org/10.21883/ftt.2021.12.51666.147.

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The structure, optical and magneto-optical properties of colloidal solutions of iron oxide nanoparticles obtained by pulsed ablation in distilled water, both without additives and with various functional additives: gold-hydrochloric acid, silicon oxide, and polyvinylpyrrolidone, have been studied. It is shown that the main magnetic phase is magnetite Fe3O4. The size distribution of nanoparticles and the degree of their agglomeration depend on the additives. In the absence of the latter, a very wide of size distributions and strong agglomeration of particles are observed. The narrowest distribution curve with a maximum corresponding to ~ 7 nm and an almost complete absence of agglomeration are observed for particles synthesized in the presence of polyvinylpyrrolidone. The shape of the spectral dependence of magnetic circular dichroism, which generally corresponds to the spectrum of magnetite, undergoes some modifications for various additives, which is associated with defects in the distribution of iron ions between different positions in the crystal.

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Kuz’menko, A. P., N. A. Leonenko, V. I. Kharchenko, N. A. Kuz’menko, I. V. Silyutin e I. V. Khrapov. "Thermocapillary mechanism of laser-stimulated agglomeration of ultradisperse and colloidal-ionic gold". Technical Physics Letters 35, n.º 9 (setembro de 2009): 837–40. http://dx.doi.org/10.1134/s1063785009090156.

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Henry, Christophe, Jean-Pierre Minier, Jacek Pozorski e Grégory Lefèvre. "A New Stochastic Approach for the Simulation of Agglomeration between Colloidal Particles". Langmuir 29, n.º 45 (30 de outubro de 2013): 13694–707. http://dx.doi.org/10.1021/la403615w.

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Gorji, Mohammad Saleh, Abdul Razak Khairunisak e Kuan Yew Cheong. "Deposition of Gold Nanoparticles on Linker-Free Silicon Substrate by Spin-Coating". Advanced Materials Research 1024 (agosto de 2014): 124–27. http://dx.doi.org/10.4028/www.scientific.net/amr.1024.124.

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Colloidal gold (Au) nanoparticles (NPs) deposition on silicon (Si) substrate is highly affected by the deposition technique and surface properties of the substrate. Spin-coating technique has been proven to be an efficient approach in terms of cost, time and maintaining the quality of the deposition. However, to prevent the agglomeration of NPs and obtain desirable density and distribution of NPs on the substrate, precise control of the spin-coating parameters is required. In this study colloidal Au NPs were spin-coated onto a modified, yet linker-free Si surface. By controlling the spinning speed, acceleration, dwelling time, and the volume of NPs colloidal solution, the density and distribution of the NPs on Si were optimized. Scanning electron microscope was used to investigate the NPs density in each step of the process. Results showed that the distribution of NPs on Si substrate is highly dependent on the spinning speed, duration, and acceleration rate as well as surface properties of Si substrate.

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Ng, Qi Hwa, Jit Kang Lim, Ahmad Abdul Latif, Boon Seng Ooi e Siew Chun Low. "Enhance the Colloidal Stability of Magnetite Nanoparticles Using Poly(sodium 4-styrene sulfonate) Stabilizers". Applied Mechanics and Materials 625 (setembro de 2014): 168–71. http://dx.doi.org/10.4028/www.scientific.net/amm.625.168.

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The major challenge in assessing the performance of magnetite nanoparticles (MNPs) in removing pollutants from wastewater is the agglomeration of those nanoparticles into a bulky cluster size. In this study, different concentration of poly (sodium 4-styrene sulfonate) (PSS) were coated around the surface of MNPs to increase the particles’ colloidal stability. Both dynamic light scattering (DLS) and thermogravimetric (TGA) analyses have proved the success coating of PSS onto MNPs, whereby the cluster size of the functionalized MNPs were shown notably depends on the applied dosage of PSS. PSS/MNPs functionalization at molar ratio of 6:1 was found to have the smallest cluster size at 148.4 ± 0.22 nm. These results have provided some insight about the particles’ colloidal stability that could be useful for environmental remediation.

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Siepmann, R., F. von der Kammer e U. Förstner. "Colloidal transport and agglomeration in column studies for advanced run-off filtration facilities - particle size and time resolved monitoring of effluents with flow-field-flowfractionation". Water Science and Technology 50, n.º 12 (1 de dezembro de 2004): 95–102. http://dx.doi.org/10.2166/wst.2004.0700.

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The efficiency of road run-off filtration facilities based on ion-exchange materials is reduced by pollutants which are transported bound to particles. To quantify the factors governing particle transport phenomena, a simplified model consisting of quartz sand-filled columns representing the filter/soil was set up. Suspensions of artificial clays, cold water-extracted natural clays, and real run-off were used as model effluents. Five experiments were performed: breakthrough of a natural soil suspension, remobilization of a natural soil suspension after ionic strength-drop, the same two experiments with a suspension of the artificial clay mineral Laponite, and the remobilization of run-off accumulated on a column at high ionic strength with an ionic strength down-gradient. Short-interval effluent fractions were analysed by flow-field-flowfractionation (F4) to obtain the size distributions of the colloids present. The size distributions of subsequent fractions were then plotted in a staggered arrangement to give three-dimensional graphs that are time- and particle size-resolved. With this method the subsequent release of different agglomerate sizes formed on the column could be shown for the artificial clay mineral, questioning its use as a model colloid. The combined particle size- and time-resolved plots proved to be a powerful tool for monitoring colloidal solids in column effluents.

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Godymchuk, Anna, Alexey Ilyashenko, Yury Konyukhov, Peter Ogbuna Offor e Galiya Baisalova. "Agglomeration and dissolution of iron oxide nanoparticles in simplest biological media". AIMS Materials Science 9, n.º 4 (2022): 642–52. http://dx.doi.org/10.3934/matersci.2022039.

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<abstract> Despite high medical and biological potential, the penetration of iron oxide nanoparticles (NPs) into a human body can cause their dissolution with subsequent accumulation of highly toxic iron compounds. The paper describes the agglomeration and dissolution behavior of differently sized α-Fe2O3 NPs in the simplest biological solutions. The average sizes of the initial NPs according to the BET analysis are 12, 32, and 115 nm. Within 30–60 min exposure, the particle size and concentration of iron released into the solutions increases in the suspensions, accompanied by an intensive change of NPs surface charge. After an hour of exposure, the colloidal properties do not change significantly, although the dissolution degree ambiguously fluctuates. It has been shown that the agglomeration of the particles in the simplest pulmonary fluid is lower than in the simplest sweat fluid, compared to the dissolution degree, which is much higher in the pulmonary fluid than in the sweat. The colloidal stability of suspensions reduces with a decrease of NPs' size, e.g., the average size of particles is 315,289, and 248 nm, while zeta potential is 2, 9, and 17 mV, respectively for 12, 32, and 115 nm NPs in 3-hour suspensions. It has been found that 24 h dissolution degree of α-Fe2O3 NPs reaches 2.3% and 0.4%, respectively, in the simplest pulmonary and sweat fluids. The mechanism of dissolution of hematite NPs in the slightly acidic and acidic mediums is proposed. </abstract>

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Capek, Ignác. "Noble Metal Nanoparticles and Their (Bio) Conjugates. I. Preparation". International Journal of Chemistry 8, n.º 1 (6 de janeiro de 2016): 74. http://dx.doi.org/10.5539/ijc.v8n1p74.

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Noble metal nanoparticles are important subjects in the field of nanotechnology. Various synthetic processes have been summarized and discussed for the preparation of noble metal nanoparticles of different sizes, shapes and solubility. Among them the colloidal fluids are most fascinating. The formation of nanoparticles starts by the reduction of metal salt and continue with the agglomeration of metal atoms to embryos, subnanoparticles and to premature metal nanoparticles. The existence of the microenvironments in the colloidal systems gives nanoparticles unique reactivity towards various molecules and additives. A soft template can be applied to synthesize noble metal nanoparticles in different-shaped biomolecules-based nanoreactors, micelles and liposomes. The size and shape of nanoparticles follows reactant feed composition, reaction conditions, presence or absence of template and type and concentration of reactants.

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Kobayashi, T., D. Bach, M. Altmaier, T. Sasaki e H. Moriyama. "Effect of temperature on the solubility and solid phase stability of zirconium hydroxide". Radiochimica Acta 101, n.º 10 (outubro de 2013): 645–51. http://dx.doi.org/10.1524/ract.2013.2074.

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Summary The solubility and solid phase stability of zirconium hydroxide was investigated in the acidic pH range after heating the aqueous samples at 50, 70 and 90 ◦C. The solubility measured at room temperature after exposing the batch samples to elevated temperatures for a given period of time significantly decreased with increasing heating periods. The Zr concentrations at given pH after heating at 90 ◦C for 3 weeks are about 5 orders of magnitude lower than the solubility of amorphous zirconium hydroxide (Zr(OH)4(am)) kept at room temperature. Size distributions of the Zr colloidal species after heating were investigated by sequential filtration using different pore-sized membranes, and the contribution of the colloidal species to the solubility was assessed. The TEM images and XRD spectra of the solid phases after heating indicated the agglomeration and crystallization of the initial amorphous hydroxide solid phase. The solid phase was identified as crystalline oxide after heating at 90◦C. The solubility product determined from the solubility data excluding contributions of colloidal species is correlated to the particle size of the solid phase.

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Taketomi, Susamu, Hiromasa Takahashi, Nobuyuki Inaba e Hideki Miyajima. "Experimental and Theoretical Investigations on Agglomeration of Magnetic Colloidal Particles in Magnetic Fluids". Journal of the Physical Society of Japan 60, n.º 5 (15 de maio de 1991): 1689–707. http://dx.doi.org/10.1143/jpsj.60.1689.

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Yang, Yung-Jih, Aniruddha V. Kelkar, David S. Corti e Elias I. Franses. "Effect of Interparticle Interactions on Agglomeration and Sedimentation Rates of Colloidal Silica Microspheres". Langmuir 32, n.º 20 (10 de maio de 2016): 5111–23. http://dx.doi.org/10.1021/acs.langmuir.6b00925.

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Schäfer, Bastian, Martin Hecht, Jens Harting e Hermann Nirschl. "Agglomeration and filtration of colloidal suspensions with DVLO interactions in simulation and experiment". Journal of Colloid and Interface Science 349, n.º 1 (setembro de 2010): 186–95. http://dx.doi.org/10.1016/j.jcis.2010.05.025.

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Weng, Ying-Chieh, I. A. Rusakova, Andrei Baikalov, J. W. Chen e Nae-Lih Wu. "Microstructural Evolution of Nanocrystalline Magnetite Synthesized by Electrocoagulation". Journal of Materials Research 20, n.º 1 (janeiro de 2005): 75–80. http://dx.doi.org/10.1557/jmr.2005.0003.

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Nanocrystalline magnetite powders were synthesized by an electrocoagulation technique, in which an electric current was passed across two plate electrodes of carbon steel immersed in NaCl(aq) electrolyte, and the microstructure of the oxide powder was found to evolve in roughly three stages. The first stage involves formation and growth of severely defective colloidal crystallites. This is followed by agglomeration among the oxide crystallites to form mesoporous agglomerates containing predominantly inter-crystallite pores, and the average crystallite size was found to reach a plateau. Finally, coarsening of the crystallites within the agglomerates leads to another rapid increase in crystallite size and reduction in pore opening. The synthesized powders typically showed a saturation magnetization of ∼75 emu/g and a coercivity Hc of ∼118 Oe. A mechanism involving competition between nucleation and growth of free colloids and coarsening of the skeletal framework was proposed to explain the temporary level-off in crystallite size during the synthesis.

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Hendrix, Douglas, Jessica McKeon e Kay Wille. "Behavior of Colloidal Nanosilica in an Ultrahigh Performance Concrete Environment Using Dynamic Light Scattering". Materials 12, n.º 12 (19 de junho de 2019): 1976. http://dx.doi.org/10.3390/ma12121976.

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The dispersion quality of nanosilica (NS) is an essential parameter to influence and control the material characteristics of nanosilica-enhanced concrete. In this research, the dispersion quality of colloidal nanosilica in simulated concrete environments was investigated using dynamic light scattering. A concrete environment was simulated by creating a synthetic pore solution that mimicked the ionic concentration and pH value of ultrahigh-performance concrete in the fluid state. Four colloidal nanosilica samples were used, ranging in particle sizes from 5 to 75 nm, with differing solid contents and stabilizing ions. It was found that the sodium stabilized 20 nm NS sol remains dispersed at a solid concentration of 2 wt % through a variety of pH values with the inclusion of potassium ions. Calcium ions are a major contributor to the agglomeration of NS sols and only small concentrations of calcium ions can drastically affect the dispersion quality.

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Díaz, Marcos, Flora Barba, Miriam Miranda, Francisco Guitián, Ramón Torrecillas e José S. Moya. "Synthesis and Antimicrobial Activity of a Silver-Hydroxyapatite Nanocomposite". Journal of Nanomaterials 2009 (2009): 1–6. http://dx.doi.org/10.1155/2009/498505.

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A silver-hydroxyapatite nanocomposite has been obtained by a colloidal chemical route and subsequent reduction process in H2/Ar atmosphere at350∘C. This material has been characterized by TEM, XRD, and UV-Visible spectroscopy, showing the silver nanoparticles (∼65 nm) supported onto the HA particles (∼130 nm) surface without a high degree of agglomeration. The bactericidal effect against common Gram-positive and Gram-negative bacteria has been also investigated. The results indicated a high antimicrobial activity forStaphylococcus aureus, PneumococcusandEscherichia coli,so this material can be a promising antimicrobial biomaterial for implant and reconstructive surgery applications.

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Tekeli, Süleyman, e Metin Gürü. "The Factors Affecting Colloidal Processing of 8YSCZ Ceramics". Key Engineering Materials 280-283 (fevereiro de 2007): 729–34. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.729.

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To achieve improvements in the mechanical properties, fine grain size, homogeneous microstructure and high density are desirable. The poor dispersion of the powders produce difficulties in the densification and the presence of agglomerates is responsible for poor mechanical properties. Slurry casting is an important colloidal processing method for the ceramic industry and helps to prevent the agglomeration of fine particles. In the present study, the effect of processing parameters, namely solid content, dispersing agent concentration, slurry viscosity and milling time on slurry casting of 8YSCZ ceramics were investigated and optimum values were determined. The results showed that ceramic powder used was castable under limited conditions. The effect of shaping processon sintering behaviour and microstructure was also investigated for slurry-cast and die-pressed specimens. The results showed that specimen processed by slurry-casting had a faster sintering rate and lower sintering temperatures, compared to die-pressed specimen. The reason for better sintering was due to the homogeneous dispersion of the powder and elimination of agglomerates in slurry-cast specimen.

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Sarkar, P., S. Panda, B. Maji e A. K. Mukhopadhyayan. "Plasmon induced quantified agglomeration of SiO2 nanoparticles to improve in efficiency in solar cell". Journal of Ovonic Research 18, n.º 6 (21 de novembro de 2022): 723–30. http://dx.doi.org/10.15251/jor.2022.186.723.

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The impact of plasmonic confinement induced by the SiO2 nanosphere utilized as a photonic absorber in a solar cell is investigated in this paper. The modified Stober technique is utilized for irradiation experiments using the size and shape of colloidal silica nanoparticles at two dosages of 0.485mg/ml and 0.693mg/ml solutions. The agglomerated silica is placed as an absorbent layer on a solar cell, and the J-V characteristics are studied under solar irradiation. The enhancement in efficiency and Jsc is far greater than predicted induced in photon injection caused by silica nanoparticle coating under coverage limit.

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Domingos, Rute F., Zohreh Rafiei, Carlos E. Monteiro, Mohammad A. K. Khan e Kevin J. Wilkinson. "Agglomeration and dissolution of zinc oxide nanoparticles: role of pH, ionic strength and fulvic acid". Environmental Chemistry 10, n.º 4 (2013): 306. http://dx.doi.org/10.1071/en12202.

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Environmental context The number of nano-enabled products reaching consumers is growing exponentially, inevitably resulting in their release to the environment. The environmental fate and mobility of nanomaterials will depend on their physicochemical form(s) under natural conditions. For ZnO nanoparticles, determinations of agglomeration and dissolution under environmentally relevant conditions of pH, ionic strength and natural organic matter content will provide insight into the potential environmental risk of these novel products. Abstract The increasing use of engineered nanoparticles (ENPs) in industrial and household applications has led to their release into the environment and increasing concern about their effects. Proper assessment of the ecological risks of ENPs will require data on their bioavailability, persistence and mobility over a broad range of physicochemical conditions, including environmentally relevant pH, ionic strength and concentrations of natural organic matter (NOM). In this study, fluorescence correlation spectroscopy was used to determine the agglomeration of a ZnO ENP (nZnO) with a nominal size of 20nm. Particle dissolution was followed using scanned stripping chronopotentiometry. The effects of Suwannee River fulvic acid (SRFA, 0–60mgL–1) and the roles of pH (4–10) and ionic strength (0.005–0.1M) were carefully evaluated. Agglomeration of the bare nZnO increased for pH values near the zero point of charge, whereas the dissolution of the particles decreased. At any given pH, an increase in ionic strength generally resulted in a less stable colloidal system. The role of SRFA was highly dependent upon its concentration with increased agglomeration observed at low SRFA : nZnO mass ratios and decreased agglomeration observed at higher SRFA : nZnO mass ratios. The results indicated that in natural systems, both nZnO dispersion and dissolution will be important and highly dependent upon the precise conditions of pH and ionic strength.

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Mackert, Viktor, Martin A. Schroer e Markus Winterer. "Unraveling agglomeration and deagglomeration in aqueous colloidal dispersions of very small tin dioxide nanoparticles". Journal of Colloid and Interface Science 608 (fevereiro de 2022): 2681–93. http://dx.doi.org/10.1016/j.jcis.2021.10.194.

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Choi, Young Joon, e Ned Djilali. "Direct numerical simulations of agglomeration of circular colloidal particles in two-dimensional shear flow". Physics of Fluids 28, n.º 1 (janeiro de 2016): 013304. http://dx.doi.org/10.1063/1.4939501.

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Im, Hee-Jung, e Euo Chang Jung. "Colloidal nanoparticles produced from Cu metal in water by laser ablation and their agglomeration". Radiation Physics and Chemistry 118 (janeiro de 2016): 6–10. http://dx.doi.org/10.1016/j.radphyschem.2015.06.005.

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Garcia-Perez, P., C. Pagnoux, A. Pringuet, A. Videcoq e J. F. Baumard. "Agglomeration of alumina submicronparticles by silica nanoparticles: Application to processing spheres by colloidal route". Journal of Colloid and Interface Science 313, n.º 2 (setembro de 2007): 527–36. http://dx.doi.org/10.1016/j.jcis.2007.04.050.

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Prorok, Vedrana, Dejan Movrin, Nataša Lukić e Svetlana Popović. "New Insights into the Fouling of a Membrane during the Ultrafiltration of Complex Organic–Inorganic Feed Water". Membranes 13, n.º 3 (14 de março de 2023): 334. http://dx.doi.org/10.3390/membranes13030334.

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This paper presents an analysis of the fouling of a ceramic membrane by a mixture containing high concentrations of humic acid and colloidal silica during cross-flow ultrafiltration under various operating conditions. Two types of feed water were tested: feed water containing humic acid and feed water containing a mixture of humic acid and colloidal silica. The colloidal silica exacerbated the fouling, yielding lower fluxes (109–394 L m−2 h−1) compared to the humic acid feed water (205–850 L m−2 h−1), while the retentions were higher except for the highest cross-flow rate. For the humic acid feed water, the irreversible resistance prevails under the cross-flow rate of 5 L min−1. During the filtration of an organic–inorganic mixture, the reversible resistance due to the formation of a colloidal cake layer prevails under all operating conditions with an exception. The exception is the filtration of the organic–inorganic mixture of a 50 mg L−1 humic acid concentration which resulted in a lower flux than the one of a 150 mg L−1 humic acid concentration under 150 kPa and a cross-flow rate of 5 L min−1. Here, the irreversible fouling is unexpectedly overcome. This is unusual and occurs due to the low agglomeration at low concentrations of humic acid under a high cross-flow rate. Under lower transmembrane pressure and a moderate cross-flow rate, fouling can be mitigated, and relatively high fluxes are yielded with high retentions even in the presence of nanoparticles. In this way, colloidal silica influences the minimization of membrane fouling by organic humic acid contributing to the control of in-pore organic fouling.

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Bantz, Christoph, Olga Koshkina, Thomas Lang, Hans-Joachim Galla, C. James Kirkpatrick, Roland H. Stauber e Michael Maskos. "The surface properties of nanoparticles determine the agglomeration state and the size of the particles under physiological conditions". Beilstein Journal of Nanotechnology 5 (15 de outubro de 2014): 1774–86. http://dx.doi.org/10.3762/bjnano.5.188.

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Due to the recent widespread application of nanomaterials to biological systems, a careful consideration of their physiological impact is required. This demands an understanding of the complex processes at the bio–nano interface. Therefore, a comprehensive and accurate characterization of the material under physiological conditions is crucial to correlate the observed biological impact with defined colloidal properties. As promising candidates for biomedical applications, two SiO2-based nanomaterial systems were chosen for extensive size characterization to investigate the agglomeration behavior under physiological conditions. To combine the benefits of different characterization techniques and to compensate for their respective drawbacks, transmission electron microscopy, dynamic light scattering and asymmetric flow field-flow fractionation were applied. The investigated particle systems were (i) negatively charged silica particles and (ii) poly(organosiloxane) particles offering variable surface modification opportunities (positively charged, polymer coated). It is shown that the surface properties primarily determine the agglomeration state of the particles and therefore their effective size, especially under physiological conditions. Thus, the biological identity of a nanomaterial is clearly influenced by differentiating surface properties.

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Yang, Yung-Jih, Aniruddha V. Kelkar, David S. Corti e Elias I. Franses. "Correction to “Effect of Interparticle Interactions on Agglomeration and Sedimentation Rates of Colloidal Silica Microspheres”". Langmuir 32, n.º 45 (2 de novembro de 2016): 11993–95. http://dx.doi.org/10.1021/acs.langmuir.6b03566.

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Jarray, A., V. Gerbaud e M. Hemati. "Structure of aqueous colloidal formulations used in coating and agglomeration processes: Mesoscale model and experiments". Powder Technology 291 (abril de 2016): 244–61. http://dx.doi.org/10.1016/j.powtec.2015.12.033.

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Suhendi, Asep, Asep Bayu Nandiyanto, Muhammad Miftahul Munir, Takashi Ogi e Kikuo Okuyama. "Preparation of agglomeration-free spherical hollow silica particles using an electrospray method with colloidal templating". Materials Letters 106 (setembro de 2013): 432–35. http://dx.doi.org/10.1016/j.matlet.2013.05.056.

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Woo, Sunyoung, Soojin Kim, Hyunhong Kim, Young Woo Cheon, Seokjoo Yoon, Jung-Hwa Oh e Jongnam Park. "Charge-Modulated Synthesis of Highly Stable Iron Oxide Nanoparticles for In Vitro and In Vivo Toxicity Evaluation". Nanomaterials 11, n.º 11 (14 de novembro de 2021): 3068. http://dx.doi.org/10.3390/nano11113068.

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The surface charge of iron oxide nanoparticles (IONPs) plays a critical role in the interactions between nanoparticles and biological components, which significantly affects their toxicity in vitro and in vivo. In this study, we synthesized three differently charged IONPs (negative, neutral, and positive) based on catechol-derived dopamine, polyethylene glycol, carboxylic acid, and amine groups, via reversible addition–fragmentation chain transfer-mediated polymerization (RAFT polymerization) and ligand exchange. The zeta potentials of the negative, neutral, and positive IONPs were −39, −0.6, and +32 mV, respectively, and all three IONPs showed long-term colloidal stability for three months in an aqueous solution without agglomeration. The cytotoxicity of the IONPs was studied by analyzing cell viability and morphological alteration in three human cell lines, A549, Huh-7, and SH-SY5Y. Neither IONP caused significant cellular damage in any of the three cell lines. Furthermore, the IONPs showed no acute toxicity in BALB/c mice, in hematological and histological analyses. These results indicate that our charged IONPs, having high colloidal stability and biocompatibility, are viable for bio-applications.

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Madsuha, Alfian F., Akhmad H. Yuwono, Nofrijon Sofyan e Michael Krueger. "Enhanced Device Performance of Bulk Heterojunction (BHJ) Hybrid Solar Cells Based on Colloidal CdSe Quantum Dots (QDs) via Optimized Hexanoic Acid-Assisted Washing Treatment". Advances in Materials Science and Engineering 2019 (1 de abril de 2019): 1–6. http://dx.doi.org/10.1155/2019/7516890.

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As-synthesized colloidal quantum dots (QDs) are usually covered by an organic capping ligand. These ligands provide colloidal stability by preventing QDs agglomeration. However, their inherent electrical insulation properties deliver a problem for hybrid solar cell application, disrupting charge transfer, and electron transport in conjugated polymer/QDs photoactive blends. Therefore, a surface modification of QDs is crucial before QDs are integrated into solar cell fabrication. In this work, enhancement of power conversion efficiency (PCE) in bulk heterojunction (BHJ) hybrid solar cells based on hexadecylamine- (HDA-) capped CdSe quantum dots (QDs) has been achieved via a postsynthetic hexanoic acid washing treatment. The investigation of the surface modification was performed to find the optimum of washing time and their effect on solar cell devices performance. Variation of washing time between 16 and 30 min has been conducted, and an optimum washing time was found at 22 min, resulting in a high PCE of 2.81%. The efficiency enhancement indicates improved electron transport, contributing in an increased short-circuit current density of solar cell devices.

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Plüisch, Claudia Simone, Rouven Stuckert e Alexander Wittemann. "Direct Measurement of Sedimentation Coefficient Distributions in Multimodal Nanoparticle Mixtures". Nanomaterials 11, n.º 4 (17 de abril de 2021): 1027. http://dx.doi.org/10.3390/nano11041027.

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Differential centrifugal sedimentation (DCS) is based on physical separation of nanoparticles in a centrifugal field prior to their analysis. It is suitable for resolving particle populations, which only slightly differ in size or density. Agglomeration presents a common problem in many natural and engineered processes. Reliable data on the agglomeration state are also crucial for hazard and risk assessment of nanomaterials and for grouping and read-across of nanoforms. Agglomeration results in polydisperse mixtures of nanoparticle clusters with multimodal distributions in size, density, and shape. These key parameters affect the sedimentation coefficient, which is the actual physical quantity measured in DCS, although the method is better known for particle sizing. The conversion into a particle size distribution is, however, based on the assumption of spherical shapes. The latter disregards the influence of the actual shape on the sedimentation rate. Sizes obtained in this way refer to equivalent diameters of spheres that sediment at the same velocity. This problem can be circumvented by focusing on the sedimentation coefficient distribution of complex nanoparticle mixtures. Knowledge of the latter is essential to implement and optimize preparative centrifugal routines, enabling precise and efficient sorting of complex nanoparticle mixtures. The determination of sedimentation coefficient distributions by DCS is demonstrated based on supracolloidal assemblies, which are often referred to as “colloidal molecules”. The DCS results are compared with sedimentation coefficients obtained from hydrodynamic bead-shell modeling. Furthermore, the practical implementation of the analytical findings into preparative centrifugal separations is explored.

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Amat, Noor Faeizah, Andanastuti Muchtar, Norziha Yahaya e Mariyam Jameelah Ghazali. "Effect of Dispersant Agent Amount in Colloidal Processing of Zirconia Dental Ceramic". Advanced Materials Research 622-623 (dezembro de 2012): 215–19. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.215.

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The effects of a polyelectrolyte dispersant agent, polyethyleneimine (PEI), on the rheology of zirconia 3Y-TZP suspensions and the densification characteristics of sintered zirconia were investigated. The colloidal processing technique was used to minimize the agglomeration of nanoparticles during the fabrication of the samples. Five batches of 10% zirconia suspensions containing different amounts of PEI at 0.3, 0.4, 0.5, 0.6, and 0.7 wt% were prepared. The rheological properties of the zirconia suspensions were determined using a rotational viscometer. The optimum amount of PEI that can maximize powders dispersion was determined. The green samples were then prepared using the slip casting process. The samples were densely sintered at a final sintering temperature of 1300 °C. The result revealed that the zirconia suspension with 0.5 wt% PEI was the most optimum amount to obtain a well-dispersed suspension. The sintered density of zirconia 3Y-TZP reached its maximum by adding 0.5 wt% PEI.

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Khlebtsov, Boris, Artur Prilepskii, Maria Lomova e Nikolai Khlebtsov. "Au-nanocluster-loaded human serum albumin nanoparticles with enhanced cellular uptake for fluorescent imaging". Journal of Innovative Optical Health Sciences 09, n.º 02 (março de 2016): 1650004. http://dx.doi.org/10.1142/s1793545816500048.

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Protein-directed fluorescent Au nanoclusters have been widely studied owing to their potential applications in sensing, imaging, and drug and gene delivery. However, the use of nanoclusters in drug delivery is limited by low cellular uptake. In this study, human serum albumin-directed Au nanoclusters served as building blocks to obtain protein nanoparticles by desolvation. The nanoparticles had a decent quantum yield (QY), high colloidal stability and low cytotoxicity, and they could be readily conjugated with biological molecules. The cellular uptake of the Au nanoclusters and nanocluster-loaded protein nanoparticles were studied by confocal fluorescence microscopy. Agglomeration of the protein-directed Au nanoclusters into 50–150-nm nanoparticles dramatically increased the cellular uptake.

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Kempken, Björn, Alexandra Erdt, Jürgen Parisi e Joanna Kolny-Olesiak. "Size Control of Alloyed Cu-In-Zn-S Nanoflowers". Journal of Nanomaterials 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/826743.

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Uniform, alloyed Cu-In-Zn-S nanoflowers with sizes of11.5±2.1 nm and31±5 nm composed of aggregated 4.1 nm and 5.6 nm primary crystallites, respectively, were obtained in a one-pot, heat-up reaction between copper, indium, and zinc acetate withtert-dodecanethiol in the presence of trioctylphosphine oxide. Larger aggregates were obtained by dilutingtert-dodecanethiol with oleylamine, which lowered the reactivity of the indium and zinc precursors and led to the formation of copper rich particles. The thermal decomposition oftert-dodecanethiol stabilizing the primary crystallites induced their agglomeration, while the presence of trioctylphosphine oxide on the surface of the nanoflowers provided them with colloidal stability and prevented them from further aggregation.

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