Advanced Materials Research Vols. 652-654

Abstract: Abstract. By using Na2S•9H2O as source precursor and citric acid as stabilizer, ZnS:Mn nanocrystallines were synthesized by solvothermal method. They were annealed at 800 oC in the charcoal powder. The structure, morphology and optical properties were investigated by using X-ray diffraction spectra (XRD), scanning electron microscopy (SEM), and Spectrofluorophotometer respectively. The results showed that all unannealed ZnS:Mn nanocrystallines were about 3~5 nm of particle size and have cubic structure, and all annealed samples were about 30-70 nm of particle size and have mixed structure of the cubic phase and hexagonal phase. Moreover, Mn2+ took the place of Zn2+ in ZnS:Mn. With the increment of Mn2+ content, there occurred a strong emission peak at about 596nm which can be attributed to the Mn2 + leap from 4T1 to 6A1. In addition, the intensity of 596nm emission peak first increased and then decreased with the increment of Mn2+ content, reaching a maximum at about 15% of Mn2+ content. After annealing Mn2+ emission peak intensity is about 20 times that before annealing, and the luminescence peak also showed slightly blue shift.

Abstract: Two-step growth technology to successfully synthesize scallion-root-shaped GaN nanorods was presented in this paper. This growth method is applicable to continuous synthesis a large number of single-crystalline GaN nanorods with a high purity at a low cost. X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) are employed to characterize the structure, composition and morphology of as-grown GaN nanorods. The results show that the obtained nanorods are single-crystal GaN with hexagonal wurtzite structure and have a relatively high purity. The diameter of the nanorods is about 500nm with length up to several tens of micrometers. The representative photoluminescence spectra (PL) measured at room temperature exhibited a strong and broad emission peak at 388nm corresponding to the strong-band-emission in wurtzite GaN, indicating that the nanorods have a good emission property. The growth mechanism is also briefly discussed.

Abstract: Carbon-encapsulated Ni nanoparticles with the size of 5 to 30 nm were synthesized from de-oiled asphalt (DOA) by heat-treatment at 1800 °C with nickel powder. The nanoparticles exhibited well-constructed core-shell structures, with Ni cores and graphitic shells. High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) examinations confirmed that the carbon-encapsulated Ni nanoparticles were uniformly dispersed in carbon matrix and the Ni nanoparticles were surrounded by several carbon layers with well ordered arrangement. The formation of the core-shell nanoparticles was selectively controlled by adjusting the ratio of de-oiled asphalt to nickel powders. The possible growth model for the carbon-encapsulated Ni nanoparticles was discussed briefly. This result presents a simple and controllable way to synthesize carbon-encapsulated nickel nanoparticles.

Abstract: A mild and efficient approach for the reduction of graphene oxide by NaHTe is reported in this work. This reductant is of low toxicity and nonvolatile and it reduce GO to graphene at room temperature in 2h. X-ray diffraction results showed that NaHTe can reduce GO completely in shorter time, comparing with hydroxylamine. Furthermore, X-ray photoelectron spectroscopy also indicates the reduction of GO to grapheme.

Abstract: To investigate mechanical properties and understand deformation mechanisms of nanocrystalline materials under high strain rate, the dynamic compression tests for nanocrystalline Ni bulk prepared by high-energy ball milling and hot-pressure sintering were carried out at different high strain rate on Hopkinson bar and a mechanical modeling based on deformation mechanism under high strain rate loading was developed. The experimental results indicate that the nanocrystalline Ni sample has higher strength and good ductility and the strength of the sample increased with the increasing strain rate. Meanwhile, The predictions by the mechanical modeling based on mechanism of dislocation gliding and grain boundary sliding at high strain rates show good agreements with the experimental data.

Abstract: CdSe nanocrystalline is an important Ⅱ - Ⅵ clan semiconductor materials, In this paper the hollow structure CdSe nanoparticles was systhesised in CTAB/cyclohexane/isobutanol/water quatemary microemulsion system. The morphology of the final products were characterized by X-ray power diffraction, transmission electron microscopy and EDS. Results of XRD and EDS revealed that nano-crystals were the mixture of CdSe, TEM images shows nanoball, nanotube and bamboo-like nanotube are hollow structure. This paper proves that the hollow structure CdSe can be obtained in the proper conditons.

Abstract: Monodisperse micron-grade silicon dioxide spherical particles have been prepared by using Stöber method. Effects of the solvents, the concentration of ammonia, TEOS and water on the particle sizes and the particle diameter distribution of silicon dioxide were investigated by scanning electron microscopy (SEM). The results show that the monodisperse micron-grade silicon dioxide spherical particles could be obtained in isopropanol solvent under a suitable reaction condition. The particle sizes increase with the decreasing of TEOS concentration. When the concentration of ammonia and water is increased, the silica particle size will increase. The particle diameter distribution narrows with the increment of the ammonia concentration and decrement of water concentration.

Abstract: Nitrogen hybrid ordered mesoporous carbons (N-OMC) were prepared by the soft-template method with melamine-phenol-formaldehyde resoles (MPF) as the precursors and triblock copolymer F127 as a soft-template. FT-IR spectra analysis demonstrated that nitrogen was incorporated into the mesoporous carbons with C-N covalent bonds. The effect of molar ratio of phenol to melamine on the pore structure and textural properties was discussed by small angle X-ray scattering, nitrogen adsorption measurements, and transmission electron microscopy. The results show that the degree of pore order decreases with the increasing of nitrogen content. The N-OMC with 3.39 wt% nitrogen has the highest specific surface areas (573m2/g) and best ordered mesostructure.

Abstract: Coaxial electrospinning has been recognized as an efficient technique for fabrication of composite fibers with especial circular cross-section in a diameter from micrometers to nanometers. In this paper, PS hollow submicro-fibers have been successfully prepared by electrospinning two polymer liquids through a coaxial, two spinneret, followed by selective removal of the core. Moreover, the influence of the relative (inner-to-outer) flow rate on the morphology and the average diameter of the fibers have been studied. The hollow submicro-fibers are particularly attractive for use in catalysis, purification, separation, gas storage, energy conversion, drug release, sensing, and environmental protection.

Abstract: Purpose: To evaluate and compare the promising applications of dextran-coated superparamagnetic iron oxide nanoparticle (dSPION) and magnetoliposome on corneal endothelial cells transplant therapy. Methods: Two kinds of novel superparamagnetic iron oxide nanoparticles (SPIONs), dSPION and magnetoliposome were synthesized, characterized and incorporated to rabbit corneal endothelial cells (RCECs). Uptakes of SPIONs were identified by Prussian blue staining. Cells migrating rates in magnetic field were calculated. Cytotoxicities of the two SPIONs were detected using MTT assay. Result: Magrating rates of dSPION (4 ~ 64 μg/mL) labled RCECs were 24.1±2.4% ~ 78.3±2.2%, and 5.0±1.7% of unlabeled RCECs. (p0.05) Conclusion: RCECs labeled with each SPION migrated significantly in external magnetic field, while cytotoxicities did not revealed. Our study demonstrated the potential applications of dSPION and magnetoliposome on labeling RCECs for cell transplantation.