Effects of hepatitis C virus core protein and nonstructural protein 4B on the Wnt/ß-catenin pathway.

BACKGROUND: Hepatitis C virus (HCV) core protein and nonstructural protein 4B (NS4B) are potentially oncogenic. Aberrant activation of the Wnt/ß-catenin signaling pathway is closely associated with hepatocarcinogenesis. We investigated the effects of HCV type 1b core protein and NS4B on Wnt/ß-catenin signaling in various liver cells, and explored the molecular mechanism underlying HCV-related hepatocarcinogenesis. RESULTS: Compared with the empty vector control, HCV core protein and NS4B demonstrated the following characteristics in the Huh7 cells: significantly enhanced ß-catenin/Tcf-dependent transcriptional activity (F = 40.87, P < 0.01); increased nuclear translocation of ß-catenin (F = 165.26, P < 0.01); upregulated nuclear ß-catenin, cytoplasmic ß-catenin, Wnt1, c-myc, and cyclin D1 protein expression (P < 0.01); and promoted proliferation of Huh7 cells (P < 0.01 or P < 0.05). Neither protein enhanced ß-catenin/Tcf-dependent transcriptional activity in the LO2 cells (F = 0.65, P > 0.05), but they did significantly enhance Wnt3a-induced ß-catenin/Tcf-dependent transcriptional activity (F = 64.25, P < 0.01), and promoted the nuclear translocation of ß-catenin (F = 66.54, P < 0.01) and the Wnt3a-induced proliferation of LO2 cells (P < 0.01 or P < 0.05). Moreover, activation of the Wnt/ß-catenin signaling pathway was greater with the core protein than with NS4B (P < 0.01 or P < 0.05). CONCLUSIONS: HCV core protein and NS4B directly activate the Wnt/ß-catenin signaling pathway in Huh7 cells and LO2 cells induced by Wnt3a. These data suggest that HCV core protein and NS4B contribute to HCV-associated hepatocellular carcinogenesis.

[Study of the physical properties of SnS thin films deposited by ultrasonic spray pyrolysis method].

In the present paper, SnS thin films were deposited by ultrasonic spray pyrolysis method. The influence of the three different precursor concentrations on the properties of SnS thin films was compared. XRD shows that when precursor solution is thiourea (0.5 mol x L(-1)) + tin tetrachloride (0.5 mol x L(-1)) + deionized water, there are SnS and SnO2 mixed phases; when precursor solution is thiourea (0.6 mol x L(-1)) + tin tetrachloride (0.5 mol x L(-1)) + deionized water, SnS phase is the dominant diffraction peak, although a certain amount of SnO2 phase is contained; when precursor solution is thiourea (0.7 mol x L(-1)) + tin tetrachloride (0.5 mol x L(-1)) + deionized water, thin film after being annealed is single SnS thin film with orthorhombic structure. SEM shows that films are uniform and dense. Furthermore, the particles of films are bigger when thiourea concentration is higher. Transmittance spectrum shows that the influence of precursor concentration on transmittance of thin films is less. Dark I-V and C-V tests of the devices show that junction characteristics of the devices were similar when prepared by three different concentrations of precursor solution, and as the thiourea concentration is higher, the carrier concentration is relatively larger.

[Spectral analysis of the effect of annealing on CdTe polycrystalline film].

Polycrystalline CdTe thin films were prepared by close-spaced sublimation (CCS) and were annealed in different condition. The thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy(XPS). The content distribution and valence state of all elements after annealing were studied. All results show that the as-deposited CdTe thin films are in a cubic phase and have the preferred orientation in (111) direction. After annealing, the peak intensity of (111), (220), (311) grows and the crystal grains grow up, while the crystal boundary decreases. So the compound probabilities of current carrier decrease, therefore shunt resistance and drain current are improved. From detailed analysis of X-ray photoelectron data, it is proposed that tellurium oxides present and its content reduces with depth increasing and that there are TeCl2O building blocks.

[Study on back contact layer of CdTe solar cell by XPS].

ZnTe and ZnTe : Cu polycrystalline films were fabricated by means of co-evaporating at room temperature. The sturcture and distribution of various elements were studied by XPS and XRD. The XRD results show that the phase structure of the films deposited at different substrate temperature almost remains unchanged, XPS analysis shows that the compositional dependence of sputtering time is different for the films deposited at different deposition rate. The distribution of Cu in the film grows with the increase in the sputtering time, and reaches a maximum, then falls down rapidly. According to the transformation of the distribution of Cu we excogitated how to prevent Cu diffusion in ZnTe films. Considering Cu as a function of time, ZnTe films were first deposited at the substrate temperature of 70 degrees C, and then ZnTe : Cu films were deposited at room temperature, effectively preventing the diffusion of Cu atom, and thus improving the efficiency of CdTe solar cells.

[Research on the polycrystalline CdS thin films prepared by close-spaced sublimation].

In the present paper, the factors of influence on the deposition rate of CdS films prepared by close-spaced sublimation (CSS) were first studied systematically, and it was found from the experiments that the deposition rate increased with the raised temperature of sublimation source, while decreased with the raised substrate temperature and the deposition pressure. The structure, morphology and light transmittance of the prepared samples were tested subsequently, and the results show: (1) The CdS films deposited under different oxygen partial pressure all present predominating growth lattice orientation (103), and further more the films will be strengthened after annealed under CdCl2 atmosphere. (2) The AFM images of CdS show that the films are compact and uniform in grain diameter, and the grain size becomes larger with the increased substrate temperature. Along with it, the film roughness was also augmented. (3) The transmittance in the shortwave region of visible light through the CdS films would be enhanced when its thickness is reduced, and that will help improve the shortwave spectral response of CdTe solar cells. Finally, the prepared CdS films were employed to fabricate CdTe solar cells, which have achieved a conversion efficiency of 10.29%, and thus the feasibility of CSS process in the manufacture of CdTe solar cells was validated primarily.

[Preparation and spectral characterization of CdS(y)Te(1-y) thin films].

CdS(y)Te(1-y) (0 < or = y < or = 1) polycrystalline thin films were prepared on glass substrates by co-evaporation of powders of CdTe and CdS. For the characterization of the structure and composition of the CdS(y)Te(1-y) thin films the X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) were used. The results indicate that the values of sulfur content y detected and controlled by the quartz wafer detector show good agreement with the EDS results. The films were found to be cubic for x < 0. 3, and hexagonal for x > or = 0.3. The 20-50 nm of grain sizes for CdS(y)Te(1-y) thin films were calculated using a method of XRD analysis. Finally, the optical properties of CdS(y)Te(1-y) thin films were characterized by UV-Vis-NIR spectroscopy alone. According to a method from Swanepoel, together with the first-order Sellmeier model, the thickness, of d-535 nm, energy gap of E(g)-1.41 eV, absorption coefficient, alpha(lambda) and refractive index, n(lambda) of CdS(0.22) Te(0.78) thin films were determined from the transmittance at normal incidence of light in the wavelength range 300-2 500 nm. The results also indicate that the CdS(y)Te(1-y) thin films with any composition (0 < or = y < or = 1) can be prepared by co-evaporation, and the method to characterize the optical properties of CdS(y)Te(1-y) thin films can be implemented for other semiconductor thin films.

[Spectral analysis of effects of annealing on the characteristics of intrinsic SnO2 polycrystalline thin films].

In order to improve the conversion efficiency of the CdTe solar cells, it is necessary to decrease the thickness of CdS layer. However, the decrease in CdS thickness may lead to adverse effects on the solar cells. Therefore, a high-resistance transparent layer (intrinsic SnO2) has been used as a buffer layer between the transparent conducting oxide (TCO) and CdS layer. In the present paper, SnO2 polycrystalline thin films were prepared by magnetic reactive sputtering. The properties of the films before and after annealing were studied by XRD and XPS. The results revealed that the films annealed at 550 degrees C for 30 minutesare polycrystalline SnO2 with a single phase of tetragonal structure and have orientation of (110) direction. XPS investigation shows that after annealing the oxygen content of the film increases, O1s peak shifts to lower energies, and SnO is oxidized into SnO2, After annealing the intrinsic SnO2 films of high-resistance as a buffer layer are very suitable for the CdTe solar cells.

[Study on ZnTe (Znte:Cu) polycrystalline films by XPS].

ZnTe and ZnTe: Cu polycrystalline films were fabricated by means of co-evaporating at room temperature. The relationships between conductivity of the films and temperature were measured. Chemical compositions of ZnTe and ZnTe: Cu polycrystalline films were obtained by using XPS, and the changes of chemical composition before and after anneal were analyzed. The results showed that the conductivity of ZnTe rose linearly with the temperature, and Te was enriched on the margin of every sample's surface; With the rise in temperature, the conductivity of ZnTe: Cu films became abnormal, the oxidization of Te became very obvious and Zn diffused from the bulk to the surface. The composition became more uniform and all peaks became stronger. Carrier concentration caused by CuxTe appeared, resulting in the abnormal relationship between conductivity of the films and temperature.