| 1. |
- Ma, Ming-Guo, et al.
(författare)
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Fabrication and characterization of Ag/calcium silicate core-shell nanocomposites
- 2011
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Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 65:19-20, s. 3069-3071
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Tidskriftsartikel (refereegranskat)abstract
- The Ag/calcium silicate nanocomposite with core-shell nanostructure has been successfully synthesized using Ag solution, Ca(NO(3))(2)center dot 4H(2)O and Na(2)SiO(3)center dot 9H(2)O in ethanol/water mixed solvents at room temperature for 48 h. Ag solution was previously prepared by microwave-assisted method in ethylene glycol (EG) at 150 degrees C for 10 min. The nanocomposites consisted of Ag core and an amorphous calcium silicate shell. The XRD and EDS results confirmed that the product was the Ag/calcium silicate nanocomposite. The TEM micrographs indicated that the Ag/calcium silicate nanocomposite was core-shell nanoparticles. The effects of Ca (NO(3))(2)center dot 4H(2)O and Na(2)SiO(3)center dot 9H(2)O concentration on the shells of Ag/calcium silicate nanocomposite were investigated. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray spectra (EDS). This method is simple, fast and may be extended to the synthesis of the other kinds of core-shell nanocomposites.
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| 2. |
- Chow, Wah Soon, et al.
(författare)
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Quantifying and monitoring functional photosystem II and the stoichiometry of the two photosystems in leaf segments : approaches and approximations
- 2012
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Ingår i: Photosynthesis Research. - Dordrecht : Springer. - 0166-8595 .- 1573-5079. ; 113:1-3, s. 63-74
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Forskningsöversikt (refereegranskat)abstract
- Given its unique function in light-induced water oxidation and its susceptibility to photoinactivation during photosynthesis, photosystem II (PS II) is often the focus of studies of photosynthetic structure and function, particularly in environmental stress conditions. Here we review four approaches for quantifying or monitoring PS II functionality or the stoichiometry of the two photosystems in leaf segments, scrutinizing the approximations in each approach. (1) Chlorophyll fluorescence parameters are convenient to derive, but the information-rich signal suffers from the localized nature of its detection in leaf tissue. (2) The gross O-2 yield per single-turnover flash in CO2-enriched air is a more direct measurement of the functional content, assuming that each functional PS II evolves one O-2 molecule after four flashes. However, the gross O-2 yield per single-turnover flash (multiplied by four) could over-estimate the content of functional PS II if mitochondrial respiration is lower in flash illumination than in darkness. (3) The cumulative delivery of electrons from PS II to P700(+) (oxidized primary donor in PS I) after a flash is added to steady background far-red light is a whole-tissue measurement, such that a single linear correlation with functional PS II applies to leaves of all plant species investigated so far. However, the magnitude obtained in a simple analysis (with the signal normalized to the maximum photo-oxidizable P700 signal), which should equal the ratio of PS II to PS I centers, was too small to match the independently-obtained photosystem stoichiometry. Further, an under-estimation of functional PS II content could occur if some electrons were intercepted before reaching PS I. (4) The electrochromic signal from leaf segments appears to reliably quantify the photosystem stoichiometry, either by progressively photoinactivating PS II or suppressing PS I via photo-oxidation of a known fraction of the P700 with steady far-red light. Together, these approaches have the potential for quantitatively probing PS II in vivo in leaf segments, with prospects for application of the latter two approaches in the field.
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| 3. |
- Hu, Jing, et al.
(författare)
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Hydrothermal preparation of boehmite-doped AgCl nanocubes and their characterization
- 2011
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Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 65:11, s. 1531-1534
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Tidskriftsartikel (refereegranskat)abstract
- A simple hydrothermal route to the preparation of the boehmite-doped AgCl nanocubes using AgNO3,AlCl3 center dot 6H(2)O and NaOH at 200 degrees C for 24 h is reported. The products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), UV-vis, thermogravimetric analysis (TGA), and differential thermal analysis (DTA). FE-SEM and TEM micrographs showed that the obtained boehmite-doped AgCl had nanocube-like morphology. The influence of heating temperature on the phase, microstructure, morphology, and thermal stability of the products were also investigated. UV-visible results indicated that the absorption edge moved to higher wavelength with the increasing heating temperature. These materials would be a promising material for photocatalyst applications.
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| 4. |
- Hu, R., et al.
(författare)
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Biofeedback neuromuscular electrical stimulation front-end for dysphagia treatment
- 2014
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Ingår i: IEEE 2014 Biomedical Circuits and Systems Conference, BioCAS 2014 - Proceedings. - : IEEE Press. - 9781479923465 ; , s. 612-615
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Konferensbidrag (refereegranskat)abstract
- A dedicated front-end for biofeedback neuromuscular electrical stimulation (NESM) system is proposed. For controllable dysphagia treatment, the integrated circuit (IC) provides a stimulator front-end with programmable stimulation parameters (2μA-1mA current amplitude, DC-2KHz frequency, and variable duty cycle) and an electromyogram/impedance (EMG/ETI) readout front-end with programmable gain and bandwidth (42-80dB, 0.1Hz-1.2KHz) for biofeedback. Area-efficient, low-power but high precision current controlling is achieved by inducing the sigma-delta modulator technique in the stimulation channel. The measured impedance and EMG signal are used to determine the stimulation parameters, enabling a closed loop optimized treatment. The proposed front-end is fabricated in a 0.18 μm standard CMOS process technology and dissipates a peak power of 2.3 mW at the supply voltage of 1.8 V. Measurement results on a live person are also provided to validate the system's effectiveness.
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| 5. |
- Jia, Ning, et al.
(författare)
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Hydrothermal fabrication, characterization, and biological activity of cellulose/CaCO3 bionanocomposites
- 2012
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 88:1, s. 179-184
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Tidskriftsartikel (refereegranskat)abstract
- Bionanocomposites with the combination of natural polymers and inorganic nanoparticles may induce unique properties and exhibit promising functions for different applications. Herein, we report a hydrothermal route to the preparation of cellulose/CaCO3 bionanocomposites using the cellulose solution. Ca(NO3)(2)center dot 4H(2)O and Na2SiO3 center dot 9H(2)O. The cellulose solution was previously prepared by the dissolution of microcrystalline cellulose in NaOH-urea aqueous solution. The urea also acts as the CO32- source for the synthesis of CaCO3. The influences of several reaction parameters, such as the heating time, the heating temperature, and the types of additives on the products were investigated by X-ray powder diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, thermogravimetric analysis, and differential thermal analysis. The experimental results demonstrated that the hydrothermal conditions had an effect on the morphology of the bionanocomposites. Cytotoxicity experiments indicated that the cellulose/CaCO3 bionanocomposites had good biocompatibility, so that the bionanocomposites could be ideal candidate for practical biomedical applications.
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| 6. |
- Jia, Ning, et al.
(författare)
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Hydrothermal Synthesis and Characterization of Cellulose-Carbonated Hydroxyapatite Nanocomposites in NaOH-Urea Aqueous Solution
- 2010
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Ingår i: Science of Advanced Materials. - : American Scientific Publishers. - 1947-2935 .- 1947-2943. ; 2:2, s. 210-214
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose-carbonated hydroxyapatite (CHA) nanocomposites with CHA nanostructures dispersed in the cellulose matrix have been successfully synthesized using microcrystalline cellulose, CaCl2, and NaH2PO4 in NaOH-urea aqueous solution by hydrothermal method. The cellulose solution was previously prepared by the dissolution of microcrystalline cellulose in NaOH-urea aqueous solution. The effects of the hydrothermal heating time, the heating temperature, and cellulose concentration on the products were investigated. The XRD and FTIR results indicated that the obtained products were the cellulose CHA nanocomposites. The SEM micrographs showed the CHA particles were dispersed in the cellulose matrix. The TGA and DTA indicated the cellulose content in the cellulose-CHA nanocomposites decreased with the decreasing raw cellulose. The size of CHA in nanocomposites decreased with the increasing preparation temperature. The products were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TG), differential thermal analysis (DTA), Fourier transform infrared spectrometry (FTIR), and scanning electron microscopy (SEM). This type of cellulose/CHA nanocomposites would be expected to be useful as novel biomedical material.
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| 7. |
- Jia, Ning, et al.
(författare)
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Microwave-assisted synthesis and characterization of cellulose-carbonated hydroxyapatite nanocomposites in NaOH-urea aqueous solution
- 2010
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Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 64:20, s. 2223-2225
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Tidskriftsartikel (refereegranskat)abstract
- We report the microwave-assisted synthesis of the cellulose-carbonated hydroxyapatite (CHA) nanocomposites with CHA nanostructures dispersed in the cellulose matrix by using the cellulose solution, CaCl2, and NaH2PO4. The cellulose solution was previously prepared by the dissolution of microcrystalline cellulose in NaOH-urea aqueous solution. The influences of the heating time and cellulose concentration on the products were also investigated. The X-ray powder diffraction (XRD) and Fourier transform infrared spectrometry (FT-IR) results indicated that the obtained products were the cellulose-CHA nanocomposites. The scanning electron microscopy (SEM) micrographs showed the CHA nanostructures were dispersed in the cellulose matrix. The thermal stability of the cellulose-CHA nanocomposites in air was investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). This method is simple, fast, low-cost and suitable for large-scale production of cellulose-based nanocomposites.
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| 8. |
- Jia, Ning, et al.
(författare)
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Synthesis and characterization of cellulose-silica composite fiber in ethanol/water mixed solvents
- 2011
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Ingår i: BioResources. - 1930-2126. ; 6:2, s. 1186-1195
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose-silica composite fiber samples have been successfully synthesized using cellulose solution, tetraethoxysilane, and NH3 center dot H2O in ethanol/water mixed solvents at room temperature for 24 h. The cellulose solution was previously prepared by the dissolution of microcrystalline cellulose in a solvent mixture of N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl). The effect of the tetraethoxysilane concentration on the product was investigated. The products were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TG), differential scanning calorimetric analysis (DSC), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), energy-dispersive X-ray spectrum (EDS), and cross polarization magic angle spinning (CP/MAS) solid state C-13-NMR. The morphology of the cellulose-silica composite fiber was investigated by SEM, while their composition was established from EDS measurements combined with the results of FT-IR spectral analysis and XRD patterns. The XRD, FT-IR and EDS results indicated that the obtained product was cellulose-silica composite fiber. The SEM micrographs showed that the silica particles were homogeneously dispersed in the cellulose fiber. The CP/MAS solid state C-13-NMR results indicated that the silica concentration had an influence on the crystallinity of the cellulose. This method is simple for preparation of cellulose-based composites.
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| 9. |
- Li, Shu-Ming, et al.
(författare)
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Rapid microwave-assisted preparation and characterization of cellulose-silver nanocomposites
- 2011
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 83:2, s. 422-429
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Tidskriftsartikel (refereegranskat)abstract
- A simple rapid and efficient microwave-assisted synthesis of cellulose-silver nanocomposites with silver nanoparticles homogeneously dispersed in the cellulose matrix using cellulose solution AgNO3 and ascorbic acid in N N-dimethylacetamide (DMAc) is reported The cellulose solution was prepared by the dissolution of microcrystalline cellulose in a solvent system of lithium chloride (LiCl)/DMAc The effects of the microwave heating times and ascorbic acid concentration on the nanocomposites were investigated The microstructure size morphology and thermal properties of these nanocomposites were analyzed with X-ray diffraction (XRD) Fourier transform infrared (FT-IR) thermogravimetric analysis (TG) differential scanning calorimetric analysis (DSC) and scanning electron microscopy (SEM) The results revealed that the ascorbic acid concentration played an important role in the phase of the nanocomposites This work provided a promising way to prepare cellulose-silver nanocomposites with good dispersity.
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| 10. |
- Li, Shu-Ming, et al.
(författare)
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Synthesis of cellulose-calcium silicate nanocomposites in ethanol/water mixed solvents and their characterization
- 2010
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 80:1, s. 270-275
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose-calcium silicate nanocomposites with calcium silicate nanoparticles homogeneously dispersed in the cellulose matrix have been successfully synthesized using cellulose solution, Ca(NO3)(2)center dot 4H(2)O and Na2SiO3 center dot 9H(2)O in ethanol/water mixed solvents at room temperature for 24 h. The cellulose solution was previously prepared by the dissolution of cellulose in a solvent system of N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl). The feeding order had an influence on the morphology of the cellulose-calcium silicate nanocomposites and the size of the calcium silicate particles. The cellulose in nanocomposites showed cellulose type II crystalline structure. The products were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TG), differential scanning calorimetric analysis (DSC), Fourier transform infrared spectrometry (FT-IR), energy-dispersive X-ray spectra (EDS), and scanning electron microscopy (SEM).
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