[en] This thesis describes mainly the studies on growth mechanism of GaN in UHV-MOVPE process, and structural and optical properties of As-doped GaN films grown by PA-MBE. In a novel Thomas Swan growth chamber, we have grown GaN films on Si substrates using TEGa, plasma nitrogen and ammonia. Using a combination of in-situ optical reflectivity and mass spectrometry, we have investigated the parameters controlling the growth process of UHV-MOVPE. In particular we have used ¹⁵N in order to distinguish gas phase species containing N from those associated purely with metal-organics. We found the surface pyrolysis of TEGa is the rate limiting step, which is similar to GaAs grown by CBE. We also identify the parasitic reactions costing the active nitrogen from plasma, which in turn limits the growth rate. Using Philips X' pert MRD, we have investigated the structural properties of As-doped GaN epitaxial films on sapphire grown by PA-MBE including phase, lattice parameters and mosacity. We have also studied the optical properties of these samples by Photoluminescence and the morphology by AFM. We have estimated the fraction of zinc-blende phase in As doped GaN, and concluded that the cubic phase is mainly related to the interface between the sapphire substrate and GaN epilayer, less possibility of N replacing As in temporally formed GaAs as we previously suspected. In the follow-up studies, we found some evidence indicating that As can occupy the Ga site as a double donor, which may be responsible for the blue emission in this As-doped GaN. We then found the N/Ga ratio dependent transition from As doped GaN to GaNAs alloy, in which alloy is formed in very N- rich conditions, this fact is not in agreement with the theoretical predication. We found some evidence that the blue emission in As-doped GaN maybe somewhat related to the strain due to the lattice mismatch. (author)

[en] China nuclear power projects investment programming model (NUPIP) is presented in this paper. Different kinds of financing approaches are analysed. The annual financing requirement is calculated according to a supposed nuclear power programme from 1991 to 2000 which may be the maximum financing amount scenario in this period. Sensitivity analyses are made for some of the variables which are of effect on financing requirement. The results show that the government investment and funds raised by localities are the principal financing resources for home-made units at the initial stage of nuclear power development, and the reserve funds from sales profits of nuclear electricity will become the important resource along with the development of nuclear power. (author). 3 tabs

[en] Fluctuation Transmission Electron Microscopy (FTEM) has a unique ability to probe topological order on the 1–3 nm length scale in diffraction amorphous materials. However, extracting a quantitative description of the order has been challenging. We report that the FTEM covariance, computed at two non-degenerate Bragg reflections, is able to distinguish different regimes of size vs. volume fraction of order. The covariance analysis is general and does not require a material-specific atomistic model. We use a Monte-Carlo approach to compute different regimes of covariance, based on the probability of exciting multiple Bragg reflections when a STEM nanobeam interacts with a volume containing ordered regions in an amorphous matrix. We perform experimental analysis on several sputtered amorphous thin films including a-Si, nitrogen-alloyed GeTe and Ge₂Sb₂Te₅. The samples contain a wide variety of ordered states. Comparison of experimental data with the covariance simulation reveals different regimes of nanoscale topological order. - Highlights: • A statistical analysis that reveals quantitative information of nanoscale order in amorphous material. • Extends upon standard nanobeam diffraction mode of Fluctuation Transmission Electron Microscopy. • General and non-model specific; does not require atomistic model to interpret the information. • The study combines theoretical development, TEM measurements, and Monte Carlo simulation results

[en] A charge integration baseline compensation method has been established and applied to the design of the spectroscopy amplifier, and the peak drifts of spectrums due to the change of count rates are efficiently decreased. In the application of X-fluorescence analysis, the drifts of the peak of silver are reduced to the range less than 0.1% while the throughput rates of the system are increased from 2000 s^-1 to 12000 s^-1

[en] In room temperature, the anodic polarization curves of Pt and Pt-Ti electrodes are determined in different concentration of HNO₃ and hydrazine. The electrolysis oxidation and catalysis decomposition of hydrazine in HNO₃ are studied. The results show that Pt-Ti electrode is better than Pt for the oxidation of hydrazine. The velocity of hydrazine electrolysis reaction increases with the increase of current density and is less affected by concentration of HNO₃. The velocity of hydrazine catalysis reaction increases with increasing the temperature and acidity. Both electrolysis oxidation and catalysis decomposition can reduce the concentration of hydrazine to 10^-5 mol/L. (authors)

[en] The interactions of Cantharidin/Norcantharidin (CTD/NCTD) with two blood proteins, i.e., bovine serum albumin (BSA) and bovine hemoglobin (BHb), have been investigated by the fluorescence, UV–vis absorption, and FT-IR spectra under imitated physiological condition. The binding characteristics between CTD/NCTD and BSA/BHb were determined by fluorescence emission and resonance light scattering (RLS) spectra. The quenching mechanism of two blood proteins with CTD/NCTD is a static quenching. Moreover, the experimental data were further analyzed based on multivariate curve resolution-alternating least squares (MCR-ALS) technique to obtain the concentration profiles and pure spectra for three species (BSA/BHb, CTD/NCTD and CTD/NCTD–BSA/BHb complexes) which existed in the interaction procedure. The number of binding sites n and binding constants K_b were calculated at various temperatures. The thermodynamic parameters (such as, ΔG, ΔH, and ΔS) for BSA–CTD/NCTD and BHb–CTD/NCTD systems were calculated by the Van’t Hoff equation and also discussed. The distance r between CTD/NCTD and BSA/BHb were evaluated according to Förster no-radiation energy transfer theory. The results of Fourier transform infrared (FT-IR), synchronous fluorescence and three-dimensional fluorescence spectra showed that the conformations of BSA/BHb altered with the addition of CTD/NCTD. In addition, the effects of common ions on the binding constants of BSA–CTD/NCTD and BHb–CTD/NCTD systems were also discussed

No abstract available

[en] The Na⁺ montmorillonite (MMT) was modified with sulfur containing amino acid (L-cystine, L-cysteine or L-methionine) and characterized by energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectrum (FT-IR). The results showed the modification was smooth and the surface condition of MMT was changed with sulfur containing groups. Then silver was loaded on the modified MMTs via ion-exchange reaction under microwave irradiation, the spectra of X-ray photoelectron spectroscopy (XPS), EDS and FT-IR confirmed the successful loading of massive silver and the strong interaction between sulfur and silver, the silver loaded L-cystine modified MMT (Ag@AA-MMT-3) with a silver content of 10.93 wt% was the highest of all. Further more, the Ag@AA-MMT-3 was under the irradiation of a UV lamp to turn silver ions to silver nano particles (Ag NPs). The XPS, specific surface area (SSA), transmission electron microscopy (TEM), XRD patterns and UV–vis spectra proved the existence of uniform nano scaled metallic Ag NPs. By contrast, the UV irradiated Ag@AA-MMT-3 (Ag@AA-MMT-UV) showed a much better slow release property than Ag@AA-MMT-3 or Ag@MMT. The Ag@AA-MMT-UV showing a large inhibition zone and high inhibition ratio presented very good antibacterial property.

No abstract available

[en] An ultrasensitive sandwich-type electrochemical immunosensor was developed for quantitative monitoring of Alpha fetoprotein (AFP). To achieve this objective, an incorporated signal amplification strategy of platinum nanoparticles anchored on cobalt oxide/graphene nanosheets (Pt NPs/Co₃O₄/graphene) was proposed by acting as the label of secondary antibodies. The prepared label not only empowered by advantages of each component but exhibited better electrochemical performance than single Pt NPs, Co₃O₄ and graphene, which has shown large specific surface area and good catalytic activity towards the reduction of H₂O₂. Meanwhile, the nanocomposite of gold nanoparticles adhered on 3-mercaptopropyltriethoxysilane functionalized graphene sheets (Au@MPTES-GS) was used as matrix to accelerate electron transfer and immobilize primary antibodies in this system. The signal amplification mechanism of the matrix and the label were explored successfully. Under optimal conditions, the electrochemical immunosensor exhibited a wide linear range from 0.1 pg mL⁻¹ to 60 ng mL⁻¹ with a low detection limit of 0.029 pg mL⁻¹for AFP. The proposed immunosensor may have promising application in the clinical diagnosis of AFP and other tumor markers. - Highlights: • An incorporated signal amplification strategy was proposed. • Co₃O₄ nanoparticles exhibited multifunctional character. • Au@MPTES-GS possesses high surface area and excellent conductivity. • The proposed immunosensor exhibited a low detection limit of 0.029 pg mL⁻¹ for AFP.