Vol.20,

413

Optical absorption of Ar and H ion beam irradiated multi-walled carbon nanotube (MWCNT) sheets at various doses in the visible and terahertz spectral ranges was investigated. It was found that the optical absorption of MWCNT sheets in the visible range was decreased with increasing ion irradiation dose. Similar behavior was observed in terahertz range, where the optical absorption of MWCNT sheets in the range of 0 to 1.5 THz was also decreased with increasing ion irradiation dose. The optical absorption decreases in irradiated MWCNT sheets can be ascribed to the increase of defects in the irradiated MWCNTs.

419

Oxygen gettering in Si by the He induced cavity layer was investigated in this work. A cavity layer was generated in Si sample by He implantation and annealing. The morphology of the cavity layer depending on the dose of He and the annealing temperature was presented in the paper. This cavity layer may serve as an efficient oxygen gettering layer during the high temperature oxidation process and accumulate the oxygen from the annealing atmosphere as well as the implanted oxygen. The phenomenon gives the idea that the cavity layer can be employed to define the oxide formation in Si and further to facilitate the formation of the buried oxide layer (BOX) in Si aiming at the Si-on-Insulator (SOI) structure fabrication. The oxygen gettering ability of the cavity layer in Si was investigated by cross section transmission electron microscopy and auger electron spectroscopy.

527

Optical absorption spectra of the mixed crystals of KBr_1-xI_x:Tl⁺ crystals studied at room temperature are reported. The absorption spectra indicated the appearance of additional bands on the low energy side of the Characteristic A, B and C absorption bands of KBr:Tl⁺ single crystals with increasing iodine composition. Comparing with earlier reports, the additional bands were attributed to the complex Tl⁺ centers in the mixed configuration surrounded by Br^-and I^- ions as nearest neighbors. The absorption spectra of gamma irradiated mixed crystals showed F band, which shifts towards low energy side with the composition of iodine ions in the mixed crystals.

451

308

Agarose gel electrophoresis was performed to study interaction effect of caffeine on photosensitive injury of DNA caused by anthraquinone-2-sulphonic acid disodium (AQS), a model compound of strong photosensitizer, under 254 nm or 365nm UV irradiation Photosensitive injury of DNA induced by AQS under deoxidized condition was used as control. The results show that caffeine may resist effectively the injury effect of photosensitive damage and strong UV irradiation on DNA. The effects depend on the caffeine and AQS concentration, and irradiation time. Caffeine in concentration of 0.01-3.0 μg/μL, may prevent DNA from damage induced by UV light, but caffeine in concentration of >5.0 μg/μL accelerates the DNA damage. In particular, in the aqueous solution system of DNA, caffeine and AQS, at pH 6.25-7.35, the caffeine in concentration of 2.5-4.50 μg/μL may resist the photosensitive injury of DNA caused by AQS under the deoxidized condition and exposure by 254 nm UV for 10 min. And caffeine in concentration of 5 μg/μL would present a synergetic effect on the photosensitive injury of DNA. Possible molecular mechanism also is discussed.

327

For a passive radon detector of Solid State Nuclear Track Detector (SSNTD), the measurement results can be affected under an environment of high humidity. In order to correct this kind of measurement errors, experiments in normal radon laboratory were performed. The track films were etched in 6.25 mol/L NaOH solution at 70°C for 12 h, and rinsed with water for 6 h. The experiment results show that calibration factor of the SSNTD decreased with increasing humidity, because of increased stopping power of the moisture-absorbed film surface to α particles. Therefore, the calibration factor K should be corrected from the calculated result.

435

423

¹⁸F-FDG PET/CT was used for evaluation of spleen infiltration in patients with B-cell non-Hodgkin lymphoma (NHL). Five patients with histological diagnosed B-cell NHL underwent ¹⁸F-FDG PET/CT examination. On integrated PET/CT image, spleen infiltration was considered when PET images revealed a discrete margin of solid splenic masses or diffuse lesion of spleen with higher maximum standardized uptake value (SUV) greater than those of normal liver structures. CT images demonstrating a positive splenic index (>480 mL) or focal hypodensities were classified as positive for spleen infiltration. All the patients underwent systemic chemotherapy. The ¹⁸F-FDG PET and CT results were compared with final diagnoses. All patients had spleen infiltration originating from B-cell NHL at final diagnosis. Final diagnoses, which were confirmed by clinical and CT (n=3) or ¹⁸F-FDG PET/CT (n=1) follow-up in 4 patients and biopsy of 1 patient. On integrated PET/CT image, ¹⁸F-FDG PET was true-positive in all 5 patients with spleen infiltration. CT was true-positive in 4 of the 5 patients with spleen infiltration and false-negative in 1 patients (spleen infiltration without morphology changes). The accuracies of ¹⁸F-FDG PET and CT for evaluating the spleen infiltration were 100% and 80% at staging, respectively. Our preliminary results suggested metabolic imaging of ¹⁸F-FDG PET/CT may be helpful in the diagnosis of spleen infiltration in B-cell NHL patients. These patients may benefit from ¹⁸F-FDG PET/CT in diagnosis, when spleen infiltration without morphology changes, which may not be diagnosed exactly by conventional image.

335

TALYS code was used to calculate excitation functions for proton induced on ^natAg, ^natCd and ¹¹³In, deuteron induced on ^natAg and alpha induced on ^natPd that lead to produce ¹⁰⁹Cd radioisotope using low and medium energy accelerators; calculates was performed out up to 50 MeV. Recommended thickness of the targets according to SRIM code was premeditated. Theoretical integral yields for any reaction were computed. TALYS 1.0 code predicts that production of a few curries of ¹⁰⁹Cd is feasible using a target of high isotopically enriched ¹¹⁰Cd, proton energy of 15 to 27 MeV, however high cost of the enriched target seems to be not a practical economic alternative to produce ¹⁰⁹Cd. The Ag+p and Ag+d processes can be an efficient route and economic for the production of millicurries of the radioisotope with incident beam energy less 15 MeV using low energy accelerator.

469

In this paper we present a timing detector which has low detection threshold and is radiation-resistant. The photons induced by radioactive beam ions passing through a thin plastic-scintillator foil BC422, emit from the foil center corresponding to one focal point of an aluminum ellipsoidal mirror and are reflected to another focus point at which the cathode of a photomultiplier tube locates. A time resolution of about 115 ps can be achieved for 12N of 58.5 MeV/u and 130 ps for 17B of 43.7 MeV/u. The counting rate up to 108 packets per second (pps) is allowed.

332

Based on the plant model of 600-MW PWR, the molten core-concrete interactions (MCCI) under different models are studied. Station blackout (SBO) with steam-driven auxiliary feed water pump failure is selected as the case for the model comparisons analysis. The result shows that thermal resistance model between debris and concrete has much influence on the consequence of MCCI. The concrete erosion rate calculated with gas film model is much higher than that of slag film model. Some other model comparisons such as the chemical reaction heat and the configuration molten pool are also discussed.

342