miR520a-3p suppresses cell proliferation and metastasis by inhibiting the p65-NFκB pathway in glioblastoma.

BACKGROUND: miR520a-3p has previously had its antitumorigenic role in various types of cancers revealed, and been predicted as a posttranscriptional regulator of the NFκB-subunit RELA gene. Thus, miR520a-3p could function in carcinogenesis through suppressing RELA. METHODS: Expression of miR520a-3p and RELA mRNA was quantified in glioma and normal tissue, and the correlation between them was analyzed statistically. Also, receiver-operating characteristic (ROC)-curve analysis was performed. Effects of miR520a-3p on cell viability, colony formation, migration, and invasion wereexplored in vitro. Whether RELA was a direct target of miR520a-3p or not was analyzed. Finally, restoration of RELA on the effect of miR520a-3p overexpression on proliferation of glioblastoma cells was detected. RESULTS: Data showed that miR520a-3p expression was aberrantly downregulated and associated with malignance in glioma tissue. Areas under ROC curves of miR520a-3p and RELA mRNA expression were 0.9483 and 0.5967, respectively. Also, miR520a-3p expression was statistically correlated with RELA mRNA level in grade III-IV glioma tissue. Transfection of miR520a-3p mimic significantly increased miR520a-3p expression, and resulted in significant suppression of proliferation, migration, and invasion of glioblastoma cells in vitro. miR520a-3p overexpression resulted in statistical downregulation of RELA, both in mRNA and protein levels. RELA was direct target of miR520a-3p. In addition, restoration of RELA significantly weakened the inhibitory effect of miR520a-3p overexpression on viability and EdU-labeled glioblastoma cells. CONCLUSION: These findings suggest that miR520a-3p should be helpful in auxiliary glioma diagnosis and can attenuate the proliferation and metastasis of glioblastoma through suppressing RELA, and thus could be an attractive therapeutic target to eliminate glioblastoma.

[The impact of ZnS/CdS composite window layer on the quantun efficiency of CdTe solar cell in short wavelength].

ZnS/CdS composite window layer was prepared by magnetron sputtering method and then applied to CdTe solar cell. The morphology and structure of films were measured. The data of I-V in light and the quantum efficiency of CdTe solar cells with different window layers were also measured. The effect of ZnS films prepared in different conditions on the performance of CdTe solar cells was researched. The effects of both CdS thickness and ZnS/CdS composite layer on the transmission in short wavelength were studied. Particularly, the quantum efficiency of CdTe solar cells with ZnS/CdS window layer was measured. The results show as follows. With the thickness of CdS window layer reducing from 100 to 50 nm, the transmission increase 18.3% averagely in short wavelength and the quantum efficiency of CdTe solar cells increase 27.6% averagely. The grain size of ZnS prepared in 250 degrees C is smaller than prepared at room temperature. The performance of CdTe solar cells with ZnS/CdS window layer is much better if ZnS deposited at 250 degrees C. This indicates grain size has some effect on the electron transportation. When the CdS holds the same thickness, the transmission of ZnS/CdS window layer was improved about 2% in short wavelength compared with CdS window layer. The quantum efficiency of CdTe solar cells with ZnS/CdS window layer was also improved about 2% in short wavelength compared with that based on CdS window layer. These indicate ZnS/CdS composite window layer can increase the photon transmission in short wavelength so that more photons can be absorbed by the absorbent layer of CdTe solar cells.

Spectral analysis of the effects of 1.7 MeV electron irradiation on the current transfer characteristic of cadmium telluride solar cells.

The effects of device performance of 1.7 MeV electron irradiation on cadmium telluride polycrystalline thin film solar cells with the structure of anti-radiation glass/ITO/ZnO/CdS/CdTe/ZnTe/ZnTe : Cu/Ni have been studied. Light and dark I-V characteristics, dark C-V characteristics, quantum efficiency (QE), admittance spectrum (AS) and other testing methods were used to analyze cells performance such as the open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF) and conversion efficiency (eta). It was explored to find out the effects of irradiation on the current transfer characteristic of solar cells combined with the dark current density (Jo), diode ideal factor (A), quantum efficiency, carrier concentration and the depletion layer width. The decline in short-circuit current was very large and the efficiency of solar cells decreased obviously after irradiation. Reverse saturation current density increased, which indicates that p-n junction characteristics of solar cells were damaged, and diode ideal factor was almost the same, so current transport mechanism of solar cells has not changed. Quantum efficiency curves proved that the damage of solar cells' p-n junction influenced the collection of photo-generated carriers. Irradiation made carrier concentration reduce to 40.6%. The analyses have shown that. A new defect was induced by electron irradiation, whose position is close to 0.58 eV above the valence band in the forbidden band, and capture cross section is 1.78 x 10(-16) cm2. These results indicate that irradiation influences the generation of photo-generated carriers, increases the risk of the carrier recombination and the reverse dark current, and eventually makes the short-circuit current of solar cells decay.

Silicon nanocrystals doping and surface modification.

Using the first-principles method based on density functional theory, at the generalized gradient approximation (GGA), the state density, the change of binding energy and the energy gap of the silicon nanocrystals (Si75H76) with the circumstances of boron (B)-doped , phosphorus (P)-doped and the surface modification with ethyl (CH2CH3), isopropyl (-CH(CH3)2) have been calculated. The results showed that the B or P-doped have little impact on the energy gap value (3.12 eV) of silicon nanocrystals (SiNcs), except that some energy levels will be introduced in the forbidden band. The energy level caused by three-coordinated B-doped SiNcs is E(c)-0.8 eV, while it is E(v) + 0.2 eV for the three-coordinated P-doped. However, the energy level position is E(v) +0.4 eV for the four-coordinated B-doped SiNcs, and E(c) -1.1 eV for the four-coordinated P-doped. Total energy of the system with the four-coordinated doped is lower than that with the three-coordinated doped in the other same conditions. The total energy of SiNcs system lessen when the surface is modified with appropriate ethyl or isopropyl. The total energy decreases with the surface coverage of organo-functional group increasing. But, the calculation can't converge because of too high resistance when the SiNcs surface are grafted with too many organic groups.

[Preparation and properties of P-type Cd1-xZn(x)Te thin films].

Cd1-xZnxTe:Cu Thin films were prepared by co-evaporation method. X-ray Fluorescence Spectrometry (XRF), scanning electron microscope(SEM), UV-Vis transmission spectra, thermal probe, four-probe method, step profiler and X-ray diffractometer (XRD) were used to investigate the composition, structure, morphology, optical and electrical properties of Cd1-x ZnxTe:Cu thin films with different doping concentration. The results show that the resistivity of 10% copper doped Cd1-x ZnxTe films increased several magnitude and the conductive type changed from p-type to n-type after annealing. The 20% cu-doped Cdl, Zn,Te films had not obvious change in conductive type and electrical resistivity after annealing and they exhibit good surface morphology. The transmissivity of 30% cu-doped Cd1-x, ZnxTe films decreased seriously below 10% after annealing, which indicate that they are not suitable to be the top cell materials in tandem structure. The 20% and 30% cu-doped Cd1-x Zn, Te films were both p-type conductivity.

[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.

[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 the back contact performances of cdte solar cells by XPS].

The metal materials with high work function should be used as the back electrode of CdTe solar cells. In the present paper, the back contact performances of CdTe solar cells with Au film and Ni film, respectively, were studied by X-ray photoelectron spectrum (XPS). After exfoliating the back electrode film, it was found that Au on the surface of ZnTe/ZnTe:Cu complex back contact layer is in the form of Au atoms and the concentration and depth of Ni diffusing into the ZnTe/ZnTe:Cu back contact layer are higher than that of Au. What's more, some Ni changes into Ni(x)+ ion which leads to rich Te ions in ZnTe/ZnTe:Cu back contact layer. So the diffusing concentration is increased, which makes the characters of CdTe improved. In the samples, the displacement of either Te or Zn peak position changes little, which indicates that both Te and Zn do not change in the modality.

[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.

[Spectral analyzing effects of atmosphere states on the structure and characteristics of CdTe polycrystalline thin films made by close-spaced sublimation].

The structure and characteristics of CdTe thin films are dependent on the working atmosphere states in close-spaced sublimation. In the present paper, CdTe polycrystalline thin films were deposited by CSS in mixture atmosphere of argon and oxygen. The physical mechanism of CSS was analyzed, and the temperature distribution in CSS system was measured. The dependence of preliminary nucleus creation on the atmosphere states (involving component and pressure) was studied. Transparencies were measured and optic energy gaps were calculated. The results show that: (1) The CdTe films deposited in different atmospheres are cubic structure. With increasing oxygen concentration, a increases and reaches the maximum at 6% oxygen concentration, then reduces, and increases again after passing the point at 12% oxygen concentration. Among them, the sample depositing at 9% oxygen concentration is the best. The optic energy gaps are 1.50-1.51 eV for all CdTe films. (2) The samples depositing at different pressures at 9% oxygen concentration are all cubical structure of CdTe, and the diffraction peaks of CdS and SnO2:F still appear. With the gas pressure increasing, the crystal size of CdTe minishes, the transparency of the thin film goes down, and the absorption side shifts to the short-wave direction. (3) The polycrystalline thin films with high quality deposit in 4 minutes under the depositing condition that the substrate temperature is 550 degrees C, and source temperature is 620 degrees C at 9% oxygen concentration.