新型骨显像剂99mTc-EDP的合成与研究

以亚磷酸二乙酯为原料,经多步反应合成了亚乙烯基二膦酸(EDP)配体.通过1HNMR测定进行了结构确认;经99mTc标记后,标记率高于95%.体外稳定性测定表明,6h后放化纯度仍保持在90%以上.小鼠体内分布实验表明,99mTc-EDP与99mTc-MDP(99mTc-亚甲基二膦酸)均具有较强的亲骨性能,99mTc-EDP骨摄取优于99mTc-MDP,并且随着时间的增加,骨与非靶器官摄取的比值都在增加,远远高于99mTc-MDP.进行了狗SPECT全身骨显像实验,2h后获得清晰的图像.     

Morphology and photoluminescence properties of ZnO nanostructures fabricated with different given time of Ar

ZnO nanostructures were grown on Au‐coated Si (100) substrates by carbonthermal reduction method with the help of Ar at the beginning of growth. The structural and optical properties of ZnO nanostructures strongly depended on the supply time of Ar. When the given time of Ar gas current was 90s, sample was ZnO nanowires with hexagonal morphology. The Raman spectroscopy revealed the low level of oxygen vacancies and Zn interstitials in samples. Room temperature photoluminescence (PL) spectra exhibited the intensity of green emission increased on the condition of rich oxygen (decrease given time of Ar) and the nanowire had strongest intensity of UV emission compared with other nanostructures. Green emission is ascribed to the electron transition from the bottom of the conduction band to the antisite defect O_Zn level. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phase diagram of a 2D Ising model within a nonextensive approach

In this work we report Monte Carlo simulations of a 2D Ising model, in which the statistics of the Metropolis algorithm is replaced by the nonextensive one. We compute the magnetization and show that phase transitions are present for q ≠ 1. A q - phase diagram (critical temperature vs. the entropic parameter q) is built and exhibits some interesting features, such as phases which are governed by the value of the entropic index q. It is shown that such phases favors some energy levels of magnetization states. It is also shown that the contribution of the Tsallis cutoff is capital to the existence of phase transitions.     

Charge, Geometry, and Effective Mass

Charge, like mass in Newtonian mechanics, is an irreducible element of electromagnetic theory that must be introduced ab initio. Its origin is not properly a part of the theory. Fields are then defined in terms of forces on either masses—in the case of Newtonian mechanics, or charges in the case of electromagnetism. General Relativity changed our way of thinking about the gravitational field by replacing the concept of a force field with the curvature of space-time. Mass, however, remained an irreducible element. It is shown here that the Reissner-Nordström solution to the Einstein field equations tells us that charge, like mass, has a unique space-time signature.     

Preparation and spectroscopic properties of Nb2O5 nanorods

Nb₂O₅ nanorods have been prepared using water/ethanol media. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible absorption and photoluminescence spectroscopy. The as-prepared Nb₂O₅ nanorods appeared to be single pseudohexagonal (TT-Nb₂O₅) phase. From the photoluminescence spectrum, two emission bands at 407 and 496 nm, respectively, were observed. The origin of the luminescence was discussed in detail.     

Optimal design of multimode interference couplers using an improved self-imaging theory

Self-imaging theory is widely accepted as a good method in designing 1 × N multimode interference (MMI) couplers, but it is also true that self-imaging theory is not suitable for low-contrast structures. An improved self-imaging theory is proposed in this paper for the optimal design of low-contrast 1 × N MMI couplers. The average effective width of MMI waveguide and the average effective propagation constant of MMI waveguide are used as the basis to modify the conventional self-imaging theory. A direct calculation of the average effective width of low-contrast MMIs is presented. We use this approach in the optimal design of a 1 × 4 silica MMI coupler, and the results show that the improved self-imaging theory is more accurate than conventional self-imaging theory for low-contrast structures, the results also show that if the material parameters and the width of an MMI waveguide are fixed, the average effective width of the MMI waveguide will increase with the decrease of the height of the core layer.     

Synthesis, microstructure and photoluminescence of Eu/Tb activated Y2SiO5 nanophosphors by new silicate sources

Y_2−xTb_xSiO₅ and Y_2−xEu_xSiO₅ nanophosphors with seven different kinds of silicate sources were synthesized by sol-gel method. The structures have been investigated to be composed of nanometer-size grains of 30-60 nm through X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to compare the different morphology of patterns from seven different silicon sources. The photoluminescence of Y_2−xTb_xSiO₅ was investigated as a function of silicate sources and the results revealed that these nanometer materials showed the characteristic emission ⁵D₄ → ⁷F_J (J = 6, 5, 4, 3) of Tb ions. The characteristic emission ⁵D₀ → ⁷F_J (J = 1, 2, 4) of Eu ions was also found in the materials of Y_2−xEu_xSiO₅.     

Wet-chemical passivation of atomically flat and structured silicon substrates for solar cell application

Special sequences of wet-chemical oxidation and etching steps were optimised with respect to the etching behaviour of differently oriented silicon to prepare very smooth silicon interfaces with excellent electronic properties on mono- and poly-crystalline substrates. Surface photovoltage (SPV) and photoluminescence (PL) measurements, atomic force microscopy (AFM) and scanning electron microscopy (SEM) investigations were utilised to develop wet-chemical smoothing procedures for atomically flat and structured surfaces, respectively. Hydrogen-termination as well as passivation by wet-chemical oxides were used to inhibit surface contamination and native oxidation during the technological processing. Compared to conventional pre-treatments, significantly lower micro-roughness and densities of surface states were achieved on mono-crystalline Si(100), on evenly distributed atomic steps, such as on vicinal Si(111), on silicon wafers with randomly distributed upside pyramids, and on poly-crystalline EFG (Edge-defined Film-fed-Growth) silicon substrates.The recombination loss at a-Si:H/c-Si interfaces prepared on c-Si substrates with randomly distributed upside pyramids was markedly reduced by an optimised wet-chemical smoothing procedure, as determined by PL measurements. For amorphous-crystalline hetero-junction solar cells (ZnO/a-Si:H(n)/c-Si(p)/Al) with textured c-Si substrates the smoothening procedure results in a significant increase of short circuit current I_sc, fill factor and efficiency η. The scatter in the cell parameters for measurements on different cells is much narrower, as compared to conventional pre-treatments, indicating more well-defined and reproducible surface conditions prior to a-Si:H emitter deposition and/or a higher stability of the c-Si surface against variations in the a-Si:H deposition conditions.     

Near-field scanning optical microscopy studies of thin film surfaces and interfaces

In this article, the results of the modeling of topography related artifacts appearing in near-field scanning optical microscopy measurements are presented. The results obtained for near-field scanning optical microscope operation in reflection mode with off-axis far field detector position are compared with experimental results. It is shown that the chosen numerical method - Finite Difference in Time Domain method (FDTD) - can be used for efficient modeling of main topography related artifact. It is also seen that the far field detector position can have large influence on the resulting reflection mode optical images.     

Temperature dependent photoluminescence down to 4.2 K in EuTFC

The temperature dependence of photoluminescence in Europium tris[3-(trifluoro-methylhydroxymethylene)-(+)-camphorate] (EuTFC) embedded in polymer films has been examined from 40 K down to 4.2 K with the goal of preparing sensor films for low-temperature thermal imaging. The behavior of EuTFC showed significant difference when based on polystyrene compared to poly(n-alkyl methacrylate)s. In poly(n-alkyl methacrylate)s prepared by standard methods for imaging applications, the photoluminescence is fully saturated below 30 K, whereas in polystyrene films there is a strong temperature dependence even down to 4.2 K. By optimizing the preparation procedure for films made of poly(butyl methacrylate) (PBMA) and poly(methyl methacrylate), also these polymers became very sensitive down to liquid helium temperature. The maximum temperature sensitivity of EuTFC in PBMA is found to be 1.0%/K at 4.2 K. The problem of delamination and cracking of the polymer film at cryogenic temperature is also avoided by the special preparation method.