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- Ma, Ming-Guo, et al.
(author)
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Hydrothermal synthesis and characterization of CePO4/C core-shell nanorods
- 2009
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In: Materials letters (General ed.). - : Elsevier B.V.. - 0167-577X .- 1873-4979. ; 63:28, s. 2513-2515
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Journal article (peer-reviewed)abstract
- The CePO4/C nanocomposite with core-shell nanostructure has been successfully synthesized using glucose and CePO4 by a facile and simple hydrothermal method at 160 °C for 24 h. The new material consists of a monoclinic CePO4 core and an amorphous-C shell. The TEM micrograph indicated that the CePO4/C nanocomposite was core-shell nanorods. The effects of glucose concentration on the C shells and luminescent intensity of CePO4/C nanocomposite were investigated. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). This method is simple, low-cost and does not need any surfactant.
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3. |
- Ma, Ming-Guo, et al.
(author)
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Solvothermal Synthesis and Characterization of Hierarchically Nanostructured Hydroxyapatite Hollow Spheres
- 2009
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In: European Journal of Inorganic Chemistry. - : Wiley-VCH Verlag GmbH & Co. - 1434-1948 .- 1099-1948 .- 1099-0682. ; :36, s. 5522-5526
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Journal article (peer-reviewed)abstract
- Hierarchically nanostructured hydroxyapatite (HA) hollow spheres assembled from nanorods have been successfully synthesized using CaCl2, NaH2PO4, and potassium sodium tartrate via a solvothermal method at 200 °C for 24 h in water/N,N-dimethylformamide (DMF) mixed solvents. The ratio of water to DMF plays a key role in the formation of hierarchically nanostructured HA hollow spheres. The potassium sodium tartrate was used as a chelating ligand and a template molecule in the synthesis and self-assembly of HA nanorods. The products were characterized by X-ray powder diffraction, and field-emission scanning electron microscopy (FESEM), transmission electron microscopy, high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectra (EDS), Brunauer-Emmett-Teller (BET), and Fourier transform infrared spectrometry. FESEM and TEM images indicated that hollow spheres of about 3.6 μ m in diameter were built by HA nanorods. On the basis of experimental results, a possible formation mechanism of these hierarchically nanostructured HA hollow spheres in the growth processes was proposed.
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4. |
- Zhou, Yan-Feng, et al.
(author)
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C4-dicarboxylates sensing mechanism revealed by the crystal structures of DctB sensor domain
- 2008
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In: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 383:1, s. 49-61
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Journal article (peer-reviewed)abstract
- C(4)-dicarboxylates are the major carbon and energy sources during the symbiotic growth of rhizobia. Responses to C(4)-dicarboxylates depend on typical two-component systems (TCS) consisting of a transmembrane sensor histidine kinase and a cytoplasmic response regulator. The DctB-DctD system is the first identified TCS for C(4)-dicarboxylates sensing. Direct ligand binding to the sensor domain of DctB is believed to be the first step of the sensing events. In this report, the water-soluble periplasmic sensor domain of Sinorhizobium meliloti DctB (DctBp) was studied, and three crystal structures were solved: the apo protein, a complex with C(4) succinate, and a complex with C(3) malonate. Different from the two structurally known CitA family of carboxylate sensor proteins CitA and DcuS, the structure of DctBp consists of two tandem Per-Arnt-Sim (PAS) domains and one N-terminal helical region. Only the membrane-distal PAS domain was found to bind the ligands, whereas the proximal PAS domain was empty. Comparison of DctB, CitA, and DcuS suggests a detailed stereochemistry of C(4)-dicarboxylates ligand perception. The structures of the different ligand binding states of DctBp also revealed a series of conformational changes initiated upon ligand binding and propagated to the N-terminal domain responsible for dimerization, providing insights into understanding the detailed mechanism of the signal transduction of TCS histidine kinases.
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