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A novel and efficient method to produce water dispersible superparamagnetic Fe3O4 nanoparticles is described. Nanoparticles prepared by non‐hydrolytic organic phase methods are subsequently functionalized with (3‐glycidyloxypropyl)trimethoxysilane, a linker that prevents aggregation and is available for subsequent coupling reactions with a wide range of polymers and biomolecules. Ring opening coupling reactions were used to coat the epoxy‐functionalized magnetite nanoparticles with aminated polymers (polyetheramines) or small molecules (arginine). The resulting nanoparticles, with hydrodynamic size of 13 nm, are found to be very stable over extended periods in water or PBS due to the presence of a dense stabilizer layer covalently anchored to the surface. Exceptionally high spin‐lattice relaxivity, r1, values of 17 s?1 mM?1, and low r2/r1 ratios of 3.3–3.8 were exhibited in the clinical MRI frequency range, irrespective of the molecule selected for nanoparticle stabilization. As a result the dispersions are excellent candidates for incorporation into multi‐functional assemblies or for use as positive contrast agent for MRI. 相似文献
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Jadambaa Temuujin Mamoru Senna Tsedev Jadambaa Dashdendev Burmaa Shaarii Erdenechimeg Kenneth JD MacKenzie 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(4):688-693
After being subjected to preliminary purification, montmorillonite clay was leached with varying concentrations of sulfuric acid (0.5–2 mol L?1) at 90 °C for varying times (0.5–4 h). Acid leaching causes partial amorphization of the montmorillonite and increases its specific surface area by a factor of 3 (from 49.1 to 157 m2 g?1). The bleaching efficiency for Mongolian mare's milk oil, as judged by light absorbance measurements at 400 nm, was increased from 9.5% for the unleached clay to 93.8% for clay leached with 2 mol L?1 H2SO4 for 4 h. Copyright © 2006 Society of Chemical Industry 相似文献
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Jadambaa Temuujin Mamoru Senna Tsedev Jadambaa Dondog Byambasuren 《Journal of the American Ceramic Society》2005,88(4):983-985
Carbothermic reduction of natural wolframite (FeWO4 ) to nano-sized tungsten carbide (WC) particles was achieved by calcining mechanically activated mixtures of FeWO4 and active carbon at 1100°C under flowing Ar gas. The average particle size ranged between 20 and 25 nm. Intermediates, Fe6 W6 C and Fe3 W3 C, were observed between 900° and 1100°C, which decomposed to give the final product, WC. Homogeneity increase and associated decrease in the diffusion path by milling are mainly responsible for the successful production of WC. The process paves the way to rational utilization of natural FeWO4 directly to fine advanced materials. 相似文献
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Covalent Functionalization of Multi‐walled Carbon Nanotubes with a Gadolinium Chelate for Efficient T1‐Weighted Magnetic Resonance Imaging
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Iris Marangon Cécilia Ménard‐Moyon Jelena Kolosnjaj‐Tabi Marie Lys Béoutis Lénaic Lartigue Damien Alloyeau Elzbieta Pach Belén Ballesteros Gwennhael Autret Tsedev Ninjbadgar Dermot F. Brougham Alberto Bianco Florence Gazeau 《Advanced functional materials》2014,24(45):7173-7186
Given the promise of carbon nanotubes (CNTs) for photothermal therapy, drug delivery, tissue engineering, and gene therapy, there is a need for non‐invasive imaging methods to monitor CNT distribution and fate in the body. In this study, non‐ionizing whole‐body high field magnetic resonance imaging (MRI) is used to follow the distribution of water‐dispersible non‐toxic functionalized CNTs administrated intravenously to mice. Oxidized CNTs are endowed with positive MRI contrast properties by covalent functionalization with the chelating ligand diethylenetriaminepentaacetic dianhydride (DTPA), followed by chelation to Gd3+. The structural and magnetic properties, MR relaxivities, cellular uptake, and application for MRI cell imaging of Gd‐CNTs in comparison to the precursor oxidized CNTs are evaluated. Despite the intrinsic T2 contrast of oxidized CNTs internalized in macrophages, the anchoring of paramagnetic gadolinium onto the nanotube sidewall allows efficient T1 contrast and MR signal enhancement, which is preserved after CNT internalization by cells. Hence, due to their high dispersibility, Gd‐CNTs have the potential to produce positive contrast in vivo following injection into the bloodstream. The uptake of Gd‐CNTs in the liver and spleen is assessed using MRI, while rapid renal clearance of extracellular Gd‐CNTs is observed, confirming the evidences of other studies using different imaging modalities. 相似文献
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Tae-Gon Cha Uyanga Tsedev Alan Ransil Amanda Embree D. Benjamin Gordon Angela M. Belcher Christopher A. Voigt 《Advanced functional materials》2021,31(35):2010867
Aerogels are ultralight porous materials whose matrix structure can be formed by interlinking 880 nm long M13 phage particles. In theory, changing the phage properties would alter the aerogel matrix, but attempting this using the current production system leads to heterogeneous lengths. A phagemid system that yields a narrow length distribution that can be tuned in 0.3 nm increments from 50 to 2500 nm is designed and, independently, the persistence length varies from 14 to 68 nm by mutating the coat protein. A robotic workflow that automates each step from DNA construction to aerogel synthesis is used to build 1200 aerogels. This is applied to compare Ni–MnOx cathodes built using different matrixes, revealing a pareto-optimal relationship between performance metrics. This work demonstrates the application of genetic engineering to create “tuning knobs” to sweep through material parameter space; in this case, toward creating a physically strong and high-capacity battery. 相似文献
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Tsedev Ninjbadgar Georg Garnweitner Alexander Börger Leonid M. Goldenberg Oksana V. Sakhno Joachim Stumpe 《Advanced functional materials》2009,19(11):1819-1825
Here, the facile synthesis of fluorescent ZrO2:Eu3+ nanoparticles with luminescence quantum yield of up to 8.7% that can be easily dispersed in organic solvents and utilized for the preparation of organic/inorganic volume holographic gratings is presented. The nanoparticles are prepared through a one‐step solvothermal process resulting in spherical particles with a mean size of 4 nm that were highly crystalline directly after the synthesis, without any need for calcination treatment. Detailed luminescence studies of the nanoparticles as a function of Eu3+ content demonstrate that the dopant concentration and its site symmetry play an important role in the emissive properties and lifetime of the luminescent centers. It is shown that the luminescence quantum yield of the colloidal ZrO2:Eu3+ nanoparticles increases with dopant concentration up to a critical concentration of 11 mol% while the luminescence lifetime is shortened from 1.8 to 1.4 ms. Holographic photopolymerization of suitable monomer mixtures containing the luminescent nanoparticles demonstrated the ability to inscribe volume Bragg gratings (refractive index contrast n1 up to 0.011) with light‐emissive properties, evidencing the high suitability of this approach for the fabrication of tailored nanomaterials for elaborate and demanding applications. 相似文献
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