Advanced Materials Research Vol. 486

Abstract: Three kinds of different diameter carbon nanotubes (CNTS) films deposited on aluminum sheets by electrophoretic deposition method. Scanning electron microscopy was used to observe the surface morphology of the films. The field emission properties of the films were tested by using a diode structure. The turn-on field for 8nm diameter CNTs film was 0.8V/μm and the current density of 5200μA/cm2 was obtained at 2.3V/μm. While corresponding data for 15nm and 30nm CNTs films were 1.6V/μm, 1.4V/μm, and 2200μA/cm2, 850μA/cm2 at 3.0V/μm respectively. The deposited film with 8nm diameter CNTs appeared excellent emission properties.

Abstract: In this article, multi-walled carbon nanotubes (MWNTs) of different aspect ratio were used to reinforce epoxy composite. The MWNTs/epoxy composites were prepared by electron beam (EB) curing process. The effect of aspect ratio on the nanomechanical properties MWNTs/epoxy nanocomposites was studied. The results showed that epoxy composites added with 0.25 wt% short MWNTs showed higher nanohardness than pure epoxy and the composite incorporation with the same amount of long MWNTs, within the indentation depth between 1500 and 2000 nm.

Abstract: The FeS₂ was synthesized using S powder, FeCl₂4H₂O and PVP as main raw materials by solvothermal method. The FeS₂ product was characterized by XRD, SEM, DRS and TG-DTA. The results show that FeS₂ is the cube structure, particle size about 90 nm, band gap energy Eg=1.9 eV. Consequently, FeS₂ nanoparticles show high visible-light photocatalytic activity for decomposition of methylene blue, which degradation rate of 10mg/L methylene blue solution can reach to 95% for 90 min under visible-light irradiation.

Abstract: In this paper, non-woven micro-/nanofibers and wavelike micro-ribbons were produced by a low-voltage near-field electrospinning with working voltage less than 2.8 kV and spinning distance less than 8 mm. A series of experiments were carried out to explore the influence of processing variables on the formation of near-field electrospun nanofibers (polyvinyl pyrrolidone (PVP) as an example), including concentration, humidity and spinning distance. The formation mechanism of helical fibers and wavelike micro-ribbons was also discussed, which can be ascribed to electrical driven bending instability and/or mechanical jet buckling when hitting the collector surface. The results indicate that the morphology of the electrospun fibers can be controlled by experimental variables. And the low-voltage near-field electrospinning is a promising technique which may be used in precision deposition of nanofibers for nanodevices, direct-write nanofabrication, etc.

Abstract: NiFe/NiFe₂O₄ core-shell bimagnetic nanocomposite particles were successfully synthesized by colloidal chemical method combined with H₂ reduction. The whole structural evolution process has been well studied through analysis of X-ray diffraction patterns and Infrared spectra. It has been found that FeNi alloy concentrated in the ferrite phase. The core/shell structure, a FeNi alloy core surrounded by NiFe₂O₄ spinel oxide shell were verified by X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The influence of post H₂ heat treatment temperature on nanoparticles was investigated. The core-shell NiFe/ NiFe₂O₄ nanoparticles was about 100 nm after reduced at 727 K, The powders exhibited paramagnetic properties and the magnetization was 29.9 emu·g^-1.

Abstract: Nanocomposite Nd₂Fe₁₄B/α-Fe magnetic material had been prepared by mechanical milling Nd₈Fe₈₆B₆ as-cast alloy in Argon and subsequent crystallization. Effect of mechanical milling and crystallization technique on its structure had been investigated by means of X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and Differential Scanning Caborimetry (DSC), etc. The crystallization behavior of amorphous Nd₈Fe₈₆B₆ powders had also been studied. The results showed that Nd₂Fe₁₄B grain refined quickly and the grain size of α-Fe decreased while extending milling time. After milling for 25h, grain size of α-Fe reached a constant (about 7nm). Higher temperature of complete crystallization as well as finer and more homogeneous grains resulted from longer milling time. During the process of crystallization, the total amorphous phase crystallized into four phases firstly, i.e., Nd_4.4Fe_77.8B_17.8, Nd_1.1Fe₄B₄, Nd₂Fe₁₄B and α-Fe. At higher temperature, final mixture was consisted of Nd₂Fe₁₄B, α-Fe and a few undecomposed Nd_1.1Fe₄B₄ phase.

Abstract: Liver is a major target of nanoparticles accumulation. Here we have analyzed the liver function and activation of liver macrophages, which are sensitive to alteration of liver internal environment after repeated exposure to aluminum oxide nanoparticles. Sprague-Dawley rats where intraperitoneally injected very two days for 60 dyas with aluminum oxide nanoparticles (50mg/kg), non-nanoaluminum oxide (50mg/kg) and saline. After 60 days exposure, the concentrations of alanine aminotransferase and aspartic transaminase in plasma were significantly higher in nanoaluminum oxide group than non-nanoaluminum oxide and control groups. The number of ED-1⁺ and GFAP⁺ cells in liver of nanoaluminum oxide and non-nanoaluminum oxide groups increased significantly than control group. Compared with non-nanoaluminum oxide, aluminum oxide nanoparticles display potential adverse effects on the hypatocytes and biliary tract of rat liver and less stimulus to macrophages in liver than non-nanoaluminum oxide. It is suggested that part aluminum oxide nanoparticles avoided from phagocytosis by liver macrophages. The effects of aluminum oxide nanoparticles exposure should be assessed for its potential hepatic toxicology.

Abstract: Elasticity of phosphorus (P)-doped silicon nanoplates has been investigated by a semi-continuum approach which captures the atomistic physics and retains the efficiency of continuum models. Youngs modulus of silicon (001) nanoplates along [10 direction is obtained by the developed semi-continuum approach. The results show that P-doping has an effect on the elasticity of silicon nanoplates, especially with the variation of doping concentration. The model predicts that Youngs moduli of P-doped silicon nanoplates are size-dependence.

Abstract: The widespread explored application of water soluble carbon nanotubes makes it important to understand their potential toxic effects on health. This study investigates the effects of phosphoryl choline grafted water soluble multi-walled carbon nanotubes (MWCNTs-PC) on human bronchial epithelial (16-HBE) cells by different cytotoxicity methods in vitro. Various concentrations of MWCNTs-PC were incubated with 16-HBE cells, the effects of cell proliferation, cell apoptosis, cell cycle and DNA damage were detected by methyl thiazolyl tetrazolium (MTT) assay, flow cytometry, single cell gel electrophoresis assay (SCGE) and micronuclear assay, respectively. Compared with the control group, there were no significant differences in the changes of cell proliferation, cell apoptosis, cell cycle and DNA damage. Within the experimental concentrations of MWCNTs-PC, no obviously cytotoxicity and DNA damage was observed on 16-HBE cells in this study.

Abstract: One method was developed for fabricating nanogap structures, which combined the nanosphere lithography, reaction ion etching and glancing deposition technologies. The results show that 10 nm-200 nm nanogaps structure could be prepared by changing the deposition angle, and nanogap structure patterns could be changed with different incident orientation.