The Diagnostic Value of Serum ST8SIA6-AS1 as Biomarker in Hepatocellular Carcinoma.

BACKGROUND: Long noncoding RNA (lncRNA) is a promising serum biomarker in cancer diagnosis. However, literature on the diagnostic value of the lncRNA for hepatocellular carcinoma (HCC) is scant. METHODS: The expression of ST8SIA6-AS1 in serum and HCC cell lines was detected by real-time PCR (RT-PCR). We then analyzed the relationship between clinicopathological characteristics and serum ST8SIA6-AS1 expression. In addition, we performed the receiver operating characteristic (ROC) curve and area under curve (AUC) analyses to determine the diagnostic ability of serum ST8SIA6-AS1. RESULTS: Our data demonstrated an up-regulation of ST8SIA6-AS1 in 77 HCC patients and HCC cell lines. Besides, clinicopathological analysis revealed that ST8SIA6-AS1 corresponds with tumor stages and metastasis, thus might be used for monitoring the HCC progress. Importantly, the ROC analysis demonstrated that ST8SIA6-AS1 yields a superior diagnostic ability. Compared with α-fetoprotein (AFP) alone, a combination of ST8SIA6-AS1 and AFP may achieve more reliable diagnostic results. CONCLUSIONS: Together, our results demonstrate that serum ST8SIA6-AS1 is a promising serum diagnostic bio-marker for HCC.

Microstructure change of ZnO nanowire induced by energetic x-ray radiation and its effect on the field emission properties.

The changes in the microstructure of ZnO nanowire were studied after exposure to different radiation doses of energetic x-rays. Detailed structural, composition and optical analyses were carried out. It was found that the surface composition changed and defects were formed in the irradiated ZnO nanowires. The structural change of ZnO nanowires after thermal treatment was also studied and similar defects were observed. It is proposed that phonon-induced localized heating is the main reason for the observed changes in microstructure. Finally, the field emission properties of ZnO nanowires before and after x-ray radiation were studied. It was found that the increase of work function and change in morphology induced by the irradiation were the reasons for the observed change in field emission properties.

Tunable field emission characteristics of ZnO nanowires coated with varied thickness of lanthanum boride thin films.

Lanthanum boride (LaB(x)) thin films with various thicknesses were deposited on ZnO nanowire arrays by electron beam evaporation. Field emission characteristics of ZnO nanowires show close dependence on LaB(x) coating thickness. The turn-on field increases with increasing LaB(x) coating thickness from 10 nm to 50 nm. The observed phenomena were explained by a model that the tunneling at ZnO/LaB(x) interface dominates the emission process.

Precisely-controlled fabrication of single ZnO nanoemitter arrays and their possible application in low energy parallel electron beam exposure.

Precisely-controlled fabrication of single ZnO nanoemitter arrays and their possible application in low energy parallel electron beam exposure are reported. A well defined polymethyl methacrylate (PMMA) nanohole template was employed for local solution-phase growth of single ZnO nanoemitter arrays. Chlorine plasma etching for surface smoothing and pulsed-laser illumination in nitrogen for nitrogen doping were performed, which can significantly enhance the electron emission and improve the emitter-to-emitter uniformity in performance. Mechanisms responsible for the field emission enhancing effect are proposed. Low voltage (368 V) e-beam exposure was performed by using a ZnO nanoemitter array and a periodical hole pattern (0.72-1.26 µm in diameter) was produced on a thin (25 nm) PMMA. The work demonstrates the feasibility of utilizing single ZnO nano-field emitter arrays for low voltage parallel electron beam lithography.

A novel lift-off method for fabricating patterned and vertically-aligned W18O49 nanowire arrays with good field emission performance.

A novel lift-off method has been developed for fabricating patterned W(18)O(49) nanowires in vertical arrays and on a large scale. These W(18)O(49) nanowire arrays have an average diameter of about 30 nm, and their lengths range from 2-3 µm. In every pattern of a 2 inch sample, the nanowires exhibit the same morphology and growth density. They are single crystals with monoclinic structure and grow along the [010] direction. Field emission (FE) measurements show that they have a turn-on field of 6.2 V µm(-1) and their emission current density can reach 500 µA cm(-2) at an electric field of 10.9 V µm(-1). Because the W(18)O(49) nanowire patterns synthesized by this simple method still have good FE performance, comparable to many cathode nanostructures with excellent FE properties, it suggests that it may provide an effective and simple preparation technique for patterned growth of nanowire arrays in future FE applications.

The effect of amorphous carbon layer on the field emission characteristics of carbon nanotube film.

Carbon nanotube (CNT) has excellent field emission characteristics and could play as a good cold cathode in the application of vacuum electronic devices. However, the practical application faces a big obstacle regarding current fluctuation and deterioration of the CNT cathode. In this research, the formation of amorphous carbon (ac) layer between the CNT film and the substrate, and the effect of the existence of this layer on field emission stability of the CNT film are studied. The formation of the ac layer could be controlled by adjustment of growth temperature and hydrocarbon flow rate. The field emission character and current stability of the CNT film without ac layer are better than those of the CNT film with ac layer. The results attribute to the ac layer a thermal disequilibrium state under high current level. Moreover, adhesion capacity of the CNT film without ac layer is also better than that with the ac layer. It is concluded that the ac layer between the CNT film and substrate is a key factor in the stability of field emission characteristics and should be eliminated before applications.

Controlled synthesis of ultra-long AlN nanowires in different densities and in situ investigation of the physical properties of an individual AlN nanowire.

The controlled synthesis of different growth densities of ultra-long AlN nanowires has been successfully realized by nitridation of Al powders for the first time. These AlN nanowires have an average diameter of about 100 nm and their mean length is over 50 µm. All the synthesized ultra-long nanowires are pure single crystalline h-AlN structures with a growth orientation of [0001]. We preferred the self-catalyzing vapor-liquid-solid (VLS) mechanism to illustrate their growth process. Although the sample with the middle growth density (3.2×10(7) per cm2) of AlN nanowire performs the best field emission (FE) properties, the emission uniformity is not good enough for field emission display applications, which may be attributed to their low intrinsic conductivity. Moreover, the electrical transport and FE properties of an individual ultra-long AlN nanowire are further investigated in situ to find the decisive factor responsible for their FE behaviors. An individual AlN nanowire is observed to have a mean 1 nA field of 440 V µm(-1) and 1 µA field of 480 V µm(-1) as well as an average electrical conductivity of about 2.7×10(-4)Ω(-1) cm(-1), which is lower than that of some cathode materials with excellent FE properties. Therefore we come to the conclusion that the electrical conductivity of the AlN nanowire must be improved to a higher level by some effective ways in order to realize their practical FE device applications.

Fabrication and field emission properties of boron nanowire bundles.

We have successfully synthesized large-scale crystalline boron nanowire bundles (BNBs) by chemical vapor deposition method. Fe(3)O(4) nanoparticles were used as catalysts spreading on ceramic substrate during the reaction process. The bundles consisted of many thin boron nanowires with a mean diameter of about 25nm and a length of several micrometers. In addition, boron nanowires are single crystals with an alpha-tetragonal structure and grow along [001] orientation. These nanowires have a surface electron affinity of 3.76eV and a work function of 4.54eV. A turn-on field of 5.1V/mum and a threshold field of 10.5V/mum were found in the nanowire bundles, and stable field emission was recorded at the same time.

Achieving uniform field emission from carbon nanotube composite cold cathode with different carbon nanotube contents: effects of conductance and plasma treatment.

A carbon nanotube (CNT) composite cold cathode was studied for field emission display application. The CNT composite cold cathode was composed of CNTs and silicon dioxide binder. Field emission from CNT composite cold cathode with different CNT contents was studied. It was found that with increase in CNT contents, the threshold field decreased. The conductance of the composite cathode was measured and with increasing CNT content, there was a critical CNT content where the conductance increased several orders of magnitude. Plasma etching using SF(6) as the etchant was adopted to treat the cathode. Improvement in emission uniformity was achieved. It was also found that after post-treatment the threshold field of the cathode decreased. The morphology of the etched cathode was analyzed and the improvement of uniformity and lowering of the threshold field was attributed to the exposure of CNTs after etching.

Study on effect of hydrogen treatment on amorphous carbon film using scanning probe microscopy.

Amorphous carbon film was treated by hydrogen plasma. The change of surface structure, conductivity, and work function distribution is characterized by scanning probe microscope technique and local electron emission is also analyzed. We find that chemical effect of hydrogen plasma on the a-C film is small, but the etching effect is strong and the surface morphology and conductance are obviously changed after hydrogen treatment. Electron emission enhancement is not due to the decrease of work function or existence of sp(2) conductive channels, but from the mutual effect between sp(2) and sp(3) phase. We suggest that the enhancement is due to the internal electron injection from the sp(2)-rich interface layer into the surface sp(3)-rich grains.

Damages of screen-printed carbon nanotube cold cathode during the field emission process.

The field emission properties of the screen-printed carbon nanotube (CNT) composite cathode have close relationship with its microstructure. In this study, carbon nanotube composite cold cathode with ZnO nano-particles as binding material was prepared using screen-printing method. Electric field cycles were used to post-treat the carbon nanotube composite cold cathode. During the process of electric field cycle treatment, obvious heat-induced damages were observed from the cathode. Scanning electron microscope and transmission electron microscope were employed to analyze the morphology and microstructure of the cathode. The possible mechanisms responsible for damages were discussed.

Self-assembly of Au-Ag alloy nanoparticles by thermal annealing.

Hemispherical Au-Ag alloy nanoparticles were prepared on 2-inch Si wafer by thermal annealing Au-Ag alloy thin film in protective ambient. The nanoparticles were evenly distributed on the substrate surface. The diameter of the nanoparticles is dependent of the deposition duration of the Au-Ag alloy thin film, and also the separation between the nanoparticles. The minimum and maximum diameters of the nanoparticles obtained so far are about 5 nm and 160 nm, respectively. Experimental evidences indicated that the formation of the hemispherical nanoparticles is due to the surface tensile stressing induced by the lattice expansion.

Preparation of Cu2S dendritic, double-comb-like nanostructures by gas-solid reaction method.

Synthesis of Cu2S dendritic nanostructures by a gas-solid reaction method has been achieved. The Cu2S dendritic nanostructure consists of a backbone and small branches aligning symmetrically and densely on the backbone like a double comb. Transmission electron microscopy has revealed that the backbone is along the c axis of monoclinic Cu2S and branches are along the b axis. Preoxidation of copper substrate is found to be important for high yield synthesis of the dendritic nanostructures. An oxide-assisted growth model is proposed to explain the formation of the dendritic nanostructures. Good field emission characteristics are also obtained from films of the dendritic Cu2S nanostructures.

Thermodynamics of diamond nucleation on the nanoscale.

To have a clear insight into the diamond nucleation upon the hydrothermal synthesis and the reduction of carbide (HSRC), we performed the thermodynamic approach on the nanoscale to elucidate the diamond nucleation taking place in HSRC supercritical-fluid systems taking into account the capillary effect of the nanosized curvature of the diamond critical nuclei, based on the carbon thermodynamic equilibrium phase diagram. These theoretical analyses showed that the nanosize-induced interior pressure of diamond nuclei could drive the metastable phase region of the diamond nucleation in HSRC into the new stable phase region of diamond in the carbon phase diagram. Accordingly, the diamond nucleation is preferable to the graphite phase formation in the competing growth between diamond and graphite upon HSRC. Meanwhile, we predicted that 400 MPa should be the threshold pressure for the diamond synthesis by HSRC in the metastable phase region of diamond, based on the proposed thermodynamic nucleation on the nanoscale.

Mechanism responsible for initiating carbon nanotube vacuum breakdown.

We report a physical mechanism responsible for initiating a vacuum breakdown process of a single carbon nanotube (CNT) during field emission. A quasidynamic method has been developed to simulate the breakdown process and calculate the critical field, critical emission current density and critical temperature beyond which thermal runaway occurs before the CNT temperature reaches its melting point. This model is in good agreement with experiments carried out with a single CNT on a silicon microtip.

Resonant field emission through amorphous diamond thin films (a model study).

A model for field emission through an amorphous diamond thin film with defects is constructed. Theoretical study shows that the emission is enhanced by attractive defects which would make the resonant emission observable for films with thickness of about 10nm. The emitted current density in typical parameters is calculated as functions of thickness, field strength and defect density. The energy distribution of emitted electrons is attained.

A cold cathode lighting element prototype.

In this study, we present a prototype of lighting element in which a carbon-containing field emission material is used as the cathode. The operating characteristics, i.e. current-voltage characteristics, current stability, luminance and lifetime of the lighting element are tested. By applying high-voltage phosphor, a maximum brightness of 10000cd/m(2) has been recorded and a lighting element under lifetime test has been operating in DC driving mode for over 2500h without decay in emission current and brightness. These results imply that the prototype lighting element is suitable for commercial application.

Effect of carbon nanotube structural parameters on field emission properties.

Experimental studies were devoted to the effect of structural parameters, i.e., tube diameter and density, on the field electron emission characteristics of carbon nanotubes. Thermal chemical vapor deposition system was employed to synthesize carbon nanotubes. Nanotubes with different diameters and densities were obtained by adjusting the thickness of the iron (Fe) catalyst film. The morphologies of the Fe and carbon nanotube film were characterized by scanning electron microscopy respectively. Further field emission measurement confirmed that the tube diameter and density could significantly affect the electron emission properties of the carbon nanotube. Possible physical reasons for the effect are discussed.

The application of carbon nanotubes in high-efficiency low power consumption field-emission luminescent tube.

In this report, details are given of our recent experimental study of using carbon nanotubes (CNTs) as cathode of the luminescent tubes. The CNT film is synthesized by thermal chemical vapor deposition. Two kinds of luminescent tubes that have different gaps have been fabricated. The luminescent tube with 0.1mm gap has a low threshold voltage of about 780V and high emission current of 300 microA when the gate voltage is 970V. The DC power consumption of the luminescent tube with a 0.1mm gap is approximately 1.12W. The results show that the CNTs are very good emission sources and suitable for application in the luminescent tube.

Study of field electron emission spectral characteristics of amorphous carbon-nitride film.

The study of field electron energy spectra from amorphous carbon-nitride (a-CN) films is essential to understand the mechanism of field emission from this promising material. In this work, the electron energy spectrum is studied by measuring the distribution of electron field emitted from individual emitting sites. The spectra are recorded at different electrical fields. It is found that the peak shift as well as the half-width increase with increasing applied fields. Furthermore, multi-peak features are observed at the low-energy side of the spectra. It is assumed that these peaks might originate from the interband states of a-CN film. We propose that although the emission mainly originates from current injection into conduction band of a-CN film, the electrons may also be emitted from interband states.