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Labeling of Pamidronate (PAM) with 99mTc was studied by a direct labeling method in the presence of SnCl2•2H2O as reducing agent. The influences of the concentration of SnCl2•2H2O, PAM concentration and pH value, reaction time on labeling yield were investigated. The optimum labeling was determined. The results showed that the radiochemistry purity of 99mTc-PAM was more than 95%. Biodistribution studies in normal mice and rats showed very high uptake of 99mTc-PAM and long retain in bone. 99mTc-PAM was washed out from the blood very quickly. In addition, considerable uptake in the kidneys indicated this complex was excreted mainly by renal pathway. On the other hand, the radioactivity in liver, lung and heart was negligible. It could be known from SPECT images that 99mTc-PAM would be an excellent bone-imaging agent. Bone uptake of 99mTc-PAM was higher than that of 99mTc-MDP in mice. This study suggested that 99mTc-PAM was a promising bone imaging agent and further study was worthwhile.

1.5 μm emission and green upconversion emission properties in In/Er-codoped LiNbO3 crystals were investigated by using both steady-state and time-resolved emission spectra. The 1.5 mol % In2O3 codoping results in the lengthening of 1.5 μm emission lifetime by 13.9% and simultaneously the shortening of 550 nm green upconversion emission lifetime by 52.5%. The decay behavior of the green upconversion emission of the In/Er-codoped crystal shows obviously nonexponential. These spectroscopic characteristics are related with the lower concentration of the cluster sites of Er3+ ion and possible cross-relaxation energy transfer processes. The above emission results are further supported by the theoretical emission results based on Judd–Ofelt theory. [ABSTRACT FROM AUTHOR]

In this study we investigated the interfacial chemistry occurring between an atomic-layer-deposited Al2O3 high-k film and a GaAs substrate and the impact of sulfidization and thermal annealing on the properties of the resultant capacitor. We observed that sulfide passivation of the Al2O3/GaAs structure improved the effect of Fermi level pinning on the electrical characteristics, thereby providing a higher oxide capacitance, smaller frequency dispersion, and reduced surface states, as well as decreased interfacial charge trapping and gate leakage currents. Photoemission analysis indicated that the (NH4)2S-treated GaAs improved the quality of the as-deposited Al2O3 thin film and preserved the stoichiometry of the dielectric during subsequent high-temperature annealing. This behavior was closely correlated to the diminution of GaAs native oxides and elemental arsenic defects and their unwanted diffusion. In addition, thermal processing under an O2 atmosphere, relative to that under N2, decreased the thickness of the Al2O3 gate dielectric and relieved the gate leakage degradation induced by metallic arsenic; as a result, superior dielectric reliability was attained. We discuss the underlying thermochemical reactions that account for these experimental observations. [ABSTRACT FROM AUTHOR]

The vinyl radical (C[sub 2]H[sub 3])òA″ ← &Xtilde;² A′ spectrum has been measured between 530 and 385 nm using cavity-ringdown spectroscopy. The active vibrational progressions involve C-C stretching and alpha H-C-C bending vibrations. Optimal rotational constants and linewidths were determined for the first four vibrational bands by modeling the spectrum as an asymmetric top. The best-fit rotational constants obtained for the excited electronic state are consistent with the molecular geometry predicted by ab initio calculations. The lifetime of the vibrationless level in the excited electronic state is estimated to be a few picoseconds, and increasing vibrational excitation leads to a decrease in the lifetime, based upon an increasing linewidth. Various possibilities for the predissociation mechanism are discussed. The most likely is judged to be a conical intersection or seam of intersections. A preliminary CASSCF calculation has found the point on the relevant potential energy surfaces at which the ground and electronically excited states are closest. While the geometry and other properties of this crossing point are in accord with the experimental results, the calculated position of the point of closest approach of the two electronic states lies considerably (> 1 eV, including zero-point energy) above the already predissociative òA″ state origin. Other mechanisms are also discussed to account for the observed rapid predissociation. Clearly there is a need for a higher level theoretical work on this problem. [ABSTRACT FROM AUTHOR]