| 1. |
- Magana, José Rodrigo, et al.
(författare)
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Self-Assembly and Formation of Chromonic Liquid Crystals from the Dyes Quinaldine Red Acetate and Pyronin Y
- 2016
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Ingår i: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 120:1, s. 250-258
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Tidskriftsartikel (refereegranskat)abstract
- The aqueous self-assembly behavior of the dyes Quinaldine red acetate and Pyronin Y in a wide range of concentrations is reported here for the first time. 1H NMR spectroscopy, polarized-light optical microscopy, and small and wide X-ray scattering were used to get insight into molecular interactions, phase boundaries and aggregate structure. Quinaldine red acetate and Pyronin Y self-organize into unimolecular stacks driven by attractive aromatic interactions. At high concentrations, spatial correlation among the molecular stacks gives rise to nematic liquid crystals in both systems. Quinaldine red acetate additionally produces a rare chromonic O phase built of columnar aggregates with anisotropic cross-section ordered in a rectangular lattice. The O phase changes into a columnar lamellar structure as a result of a temperature-induced phase transition. Results open the possibility of finding chromonic liquid crystals in other commercially available dyes with a similar molecular structure. This would eventually expand the availability of these unique soft materials and thus introduce new applications for marketed dyes.
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| 2. |
- Okoli, Chuka, et al.
(författare)
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Comparison and Functionalization Study of Microemulsion-Prepared Magnetic Iron Oxide Nanoparticles
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:22, s. 8479-8485
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic iron oxide nanoparticles (MION) for protein binding and separation were obtained from water-in-oil (w/o) and oil-in-water (o/w) microemulsions. Characterization of the prepared nanoparticles have been performed by TEM, XRD, SQUID magnetometry, and BET. Microemulsion-prepared magnetic iron oxide nanoparticles (ME-MION) with sizes ranging from 2 to 10 rim were obtained. Study on the magnetic properties at 300 K shows a large increase of the magnetization similar to 35 emu/g for w/o-ME-MION with superparamagnetic behavior and nanoscale dimensions in comparison with o/w-ME-MION (10 emu/g) due to larger particle size and anisotropic property. Moringa oleifera coagulation protein (MOCP) bound w/o- and o/w-ME-MION showed an enhanced performance in terms of coagulation activity. A significant interaction between the magnetic nanoparticles and the protein can be described by changes in fluorescence emission spectra. Adsorbed protein from MOCP is still retaining its functionality even after binding to the nanoparticles, thus implying the extension of this technique for various applications.
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| 3. |
- Sanchez-Dominguez, Margarita, et al.
(författare)
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A novel approach to metal and metal oxide nanoparticle synthesis : the oil-in-water microemulsion reaction method
- 2009
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Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 11:7, s. 1823-1829
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Tidskriftsartikel (refereegranskat)abstract
- A novel and straightforward approach, based on oil-in-water (o/w) microemulsions, was developed for the synthesis of inorganic nanoparticles at ambient conditions. It implies the use of organometallic precursors dissolved in nanometre-scale oil droplets of o/w microemulsions. Addition of reducing or oxidizing/precipitating agents results in the formation of metallic or metal oxide nanoparticles, respectively. Nonionic o/w microemulsion systems were chosen, and several key compositions were selected for nanoparticle synthesis at 25 A degrees C. High Resolution Electron Microscopy revealed that small nanoparticles of metals (Pt, Pd and Rh) and nanocrystalline metal oxide (cerium (IV) oxide with cubic type crystalline structure confirmed by XRD), of less than 7 nm can be obtained in mild conditions.
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| 4. |
- Sanchez-Dominguez, Margarita, et al.
(författare)
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Synthesis of CeO2, ZrO2, Ce0.5Zr0.5O2, and TiO2 nanoparticles by a novel oil-in-water microemulsion reaction method and their use as catalyst support for CO oxidation
- 2010
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 158:1-2, s. 35-43
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Tidskriftsartikel (refereegranskat)abstract
- A novel and straightforward approach for the synthesis of mesoporous inorganic oxide nanoparticles, with a small particle size and high specific surface area is reported, by using oil-in-water microemulsions, in contrast to the typically used water-in-oil microemulsion method. The new strategy implies the use of organometallic precursors, dissolved in nanometer-scale oil droplets (stabilised by surfactant), and dispersed in a continuous aqueous phase. The potential of this approach is explored for producing nanocrystalline ceria, zirconia, ceria/zirconia mixed oxide and titania. Nanocrystalline cubic CeO2 and Ce0.5Zr0.5O2 were obtained under soft conditions, whilst ZrO2 and TiO2 presented wide X-ray diffraction peaks. The specific surface area (SSA) of the obtained materials was in the order of 200-370 m(2)/g and the particle size was very small (similar to 2-3 nm). The materials were calcined at 400 degrees C after which a high SSA was maintained (100-150 m(2)/g) and the crystallinity was improved, yielding tetragonal phases for both TiO2 (anatase) and ZrO2. The potential of the calcined materials as catalyst support was explored in the CO oxidation reaction by doping the oxides with Au (2 wt%). The obtained results demonstrate the feasibility of this approach for the preparation of various supports with high SSA for catalytic purposes.
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