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In this paper, we studied how field emission from thermally evaporated W18O49 nanowires depended on temperature. As the temperature changed from 300K to 723 K, we found anomalous changes in emission current. Below an applied field of ∼12.5V μm-1, the emission current tended to increase with rising temperature, while above 12.5V μm-1 the current depended less on temperature in the range of 573-723 K. Furthermore, at high temperatures, we found the Fowler-Nordheim plots of these nanowires to be nonlinear. We believe that the anomalous behavior is associated with surface states at low fields and field penetration at high fields. [ABSTRACT FROM AUTHOR]

Improvement in the field emission properties of α-Fe2O3 nanoflakes is observed after high energy X-ray irradiation from synchrotron radiation. Field emission threshold field of α-Fe2O3 nanoflakes is found to decrease from 10.1 to 7.8 MV/m after X-ray irradiation with the dose of 9.0 × 1014 phs/cm2. Electrical measurement reveals that the potential barrier at the back contact between the α-Fe2O3 layer and the iron substrate changes after X-ray irradiation. The observed threshold field decrease is well explained by the changes in potential barrier at the back contact of α-Fe2O3 nanoflakes, which indicates the back contact plays an important role in controlling the field emission properties of α-Fe2O3 nanoflakes. Our study shows that the α-Fe2O3 nanoflakes are a promising material for the application as field emitter under X-ray environment. [ABSTRACT FROM AUTHOR]

For field emission from wide-band-gap semiconductor nanostructures, nonlinear plots on Fowler-Nordheim (FN) coordinates and unacceptably large field enhancement factors (βFN) are often obtained by fitting based on FN equation. In the present work, the field-induced hot-electron emission model is developed and is found to give theoretical findings consistent with the experimental observation. The hot electrons are produced by heating effect of penetration field into the emitting tip of the nanostructure. This energy is expressed by effective electron temperature Te, which is much higher than the temperature of bulk structure. By combining the effective electron temperature with thermal emission function and Murphy and Good integration function, the relation between emission current density and external field is derived and the field enhancement factor (βTe) can be calculated quantitatively. For evaluation of the theoretical model, ZnO nanostructure is selected as a concrete example. The results are found to agree with experiment findings. Extremely large field enhancement factor is not needed in our model and nonlinear property of saturation region emerges in nature in our calculation. [ABSTRACT FROM AUTHOR]

Pulsed-laser (neodymium doped yttrium aluminum garnet; 1.06 μm in wavelength) treatments were performed on zinc oxide (ZnO) nanowires (NWs) in nitrogen. It results in nitrogen doping of ZnO, mainly with chemical states of N2 at oxygen sites, which is demonstrated by x-ray photoelectron spectroscopy studies. The laser treated ZnO NWs show significant improvement in electrical conduction and field emission. Typically, with the critical treated conditions of peak power 400 W and pulse duration 2 ms, NWs with the highest conductivity of 1.43×10-2 S/cm was obtained. It is one order of magnitude higher than that of the as-prepared NWs (1.20×10-3 S/cm). These NWs show better field electron emission properties. The turn-on field is 2.0 MV/m and a current density of 5.3 mA/cm2 can be obtained at a field of 3.0 MV/m. The underlying mechanisms related to the enhancing effect of conduction and field emission were discussed. The pulsed-laser treatment may be developed toward a technique for application in the study of nanoelectronic devices using NWs. [ABSTRACT FROM AUTHOR]

A phenomenon of field emission instability is reported. Field emission current oscillation was observed when a single zinc oxide (ZnO) one dimensional nanostructure operated at high current density. As a result, the radius curvature of the nanoemitter apex was sharpened to less than 15 nm. This indicates the oscillation was associated with melting of the emitter material. We found that the oscillation may be ascribed to (i) the behavior of charging and (ii) the shape changing of a metallic liquid ball that exists at the tip apex under high electric field. The net force of electric force and surface tension modifies the radius of the apex periodically, which results in the oscillation of field emission current. This finding may enhance the understanding of the physical process of field emission from ZnO nanostructures. [ABSTRACT FROM AUTHOR]

The field emission characteristics of amorphous carbon (a-C) films are studied before and after H plasma treatment. It is found that H plasma treatment lowered the turn-on field and improved the field emission uniformity. Surface sp2/sp3 ratio, work function, and topography of the a-C films before and after H plasma treatment are studied using Raman spectroscopy, Kelvin probe, and atomic force microscopy, respectively. The results show that the etching effect of H plasma on a-C film is obvious, which is different from those of diamond and tetrahedral amorphous carbon (ta-C) films. We suggest that the surface component change and nanostructure of treated a-C films cause electron injection from sp2 sites to surface sp3 sites which are responsible for low macroelectrical field emission. [ABSTRACT FROM AUTHOR]

The degradation and damage of carbon nanotube (CNT) films caused by field emission were investigated by carefully studying the effect of emission current density of different levels on the CNT film. It is found that the behavior of the vacuum breakdown of a CNT film is very different from a metal cathode. A critical emission current density may be identified, 500 A/m2, for example, for our present samples, below which the evaporation of CNT tips and breaking at defect sites of a group of CNTs of long length are the major causes of damage to the CNT film. When the emission current density is higher than the critical value, microarcing gives rise to significant catastrophic damage to the CNT film. A theoretical model proposed early for CNT vacuum breakdown was adapted to explain the present findings, which assumes thermal runaway as an initiating mechanism for CNT vacuum breakdown, taking into account the important role of Joule heating. [ABSTRACT FROM AUTHOR]

Films of aligned crystalline copper sulphide (Cu[sub 2]S) nanowire arrays were grown by using a gas-solid reaction method. By controlling the preparation condition, copper sulphide nanowire arrays with different structural parameters were fabricated. Their field emission characteristics including the total current-applied field characteristics and the distribution of field emission sites are studied and compared using the transparent anode technique. It is found that the turn-on field of the copper sulphide nanowire film relates to the structural parameters of copper sulphide nanowire arrays. Nonlinearity in Fowler-Nordheim plot was observed from film consisting of sparse nanowire arrays with varied field enhancement factor. The physical mechanism accounting for the nonlinearity is discussed. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Kinesin family member 14 (KIF14) is a mitotic kinesin and plays an important role in tumor progression. KIF14 overexpression has been observed in multiple cancers and has been correlated with a poor prognosis. However, its protein expression and prognostic significance in epithelial ovarian cancer (EOC) remain unclear. In this research, we aimed to explore the relationship of KIF14 expression with clinicopathological parameters and prognosis in EOC. MATERIALS AND METHODS: In this study, we measured KIF14 expression in 170 EOC carcinoma tissue samples with immunohistochemistry and correlated these data with clinicopathological characteristics. RESULTS: The expression of KIF14 in EOC tissues was significantly higher than that in normal tissues. Furthermore, KIF14 expression was significantly associated with metastasis (p = 0.047), histological type (p = 0.001), Ki67 expression (p = 0.004) and residual tumor (p = 0.038). Also, Kaplan-Meir survival curves showed that a high level of KIF14 expression was a predictor for worse PFS (p = 0.013) and OS (p = 0.009) in patients with EOC. CONCLUSIONS: KIF14 expression may be associated with poor prognosis, suggesting that it has potential value as an effective prognostic predictor in EOC patients. [ABSTRACT FROM AUTHOR]