Vol.15,

276

414

The influence of surface barrier of solid upon ion reflection was studied in a few papers of other authors by using the Monte-Carlo simulation. Based on the bipartition model of ion transport, a new analytical theory has been developed instead of the MC simulation, due to important implication of the effect for fusion research. In the present paper we have calculated the number reflection coefficients of H⁺, D⁺, He and T⁺ normally incident on C, Al and Cu for ion energy from several eV to one hundred keV respectively. Our computational results accorded with the MC simulation. The results have shown that the effect of surface barrier on ion reflection becomes evident when the energy of incident ions is lower than one keV. In particular, for the ion energy from several eV to one hundred eV, the discrepancies of number reflection coefficients can increase up to 0.1~0.3, showing this influence to be very important.

528

Fe ions in the fluence range of 2×10¹⁵ to 1×10¹⁷ cm^-2 were implanted into diamond-like carbon (DLC) thin film of 100 nm thick, which were deposited on silicon substrate by plasma enhanced chemical vapor deposition. Effects of Fe ion implantation on microstructure and friction coefficient of the DLC were studied. With increasing Fe ion fluence, friction coefficient of the DLC film increased as compared with that of DLC without implantation, and then decreased. The Raman spectra characteristics also show a dependence on the Fe ion fluence. With increasing the ion fluence, the sp² bonding increased in the DLC film, resulting in the decrease of friction coefficient of the film after implantation. Substantial surface roughness was also measured.

295

With the development of planta genetic engineering, more emphases have been laid on convenient and high efficient genetic transformation methods. And transformation without tissue culture is a prospective direction of it. In this paper, traditional transformation methods and the methods of non-tissue culture were summarized. With the exploration and application of Arabidopsis transformation mechanism, with the use of ion beam-mediated transformation invented by Chinese scientists and the development of other transformation methods, transformation methods without tissue culture and planta genetic engineering could be improved rapidly.

306

HEDTMP (N-(2-hydroxyethyl) ethlenediamine-1,1,2-tri(methylene phosphonic acid)) was labeled with ¹⁵³Sm. The formation condition, stability, rabbit bone imaging and mouse bio-distribution of ¹⁵³Sm -HEDTMP were investigated. The results showed that weak basic media and high ligand's concentration were favorable to form ¹⁵³Sm-HEDTMP, and neutral or weak basic media increase the stability of ¹⁵³Sm-HEDTMP. And the higher the concentration of HEDTMP was, the more stable the labeling complex was. Bio-distribution study indicated the uptake of ¹⁵³Sm-HEDTMP in skeleton was high ((25.68±1.22)ID%/g bone at 3 h post injection and (16.56±1.01)ID%/g bone at 48 h post injection), while the non-target tissue uptake and retention were relatively low, so ¹⁵³Sm-HEDTMP is a promising bone tumor therapeutic agent.

296

The apoptosis in human bone tumor cells induced by internal irradiation with ¹⁵³Sm was studied. The morphological changes in bone tumor cells were observed by electronic and fluorescent microscopy, as well as DNA agarose gel eletrophoresis. DNA chain fragmentation, microautoradiographic tracing and the inhibition rate of proliferation in bone tumor cells exposed to ¹⁵³Sm with different duration time were examined. It was demonstrated that the bone tumor cells exposed to ¹⁵³Sm displayed nuclear fragmentation, pyknosis, margination of condensed chromatin, and formation of membrane bounded apoptotic bodies, whereas the percentage of DNA chain fragmentation of bone tumor cells increases in direct proportion to the duration of irradiation with ¹⁵³Sm, as well as DNA ladder formation in apoptotic cells. Also a marked inhibition effect of proliferation in bone tumor cells after exposure with ¹⁵³Sm was observed.

291

To study the radioiodinating condition of interleukin-8(IL-8) and observe its biodistribution in mice for understanding the possibility of its application in nuclear medicine, we labelled IL-8 with ¹²⁵I using Bolton-hunter reagent, and the distributions in mice at 5 min, 30 min, 1h, 6h and 24h after injection of ¹²⁵I –IL-8 were measured. The blood clearance curve was obtained and fitted with the two-compartment model. The results showed that ¹²⁵I-IL-8 was obtained with a labeling efficiency of 12.2% ±6.5% and a radiochemical purity of 91.4%±6.5%. Its specific activity was 14.8 kBq/μg IL-8. A fast phase half – life T_1/2αof 0.32 h and a slow phase half – life T_1/2β of 8.01 h were calculated from the blood clearance curve. The uptakes of radioactivities in kidneys and lung had the peaks of 85.87%ID /g and 16.17%ID /g at 30 min after intravenous injection, respectively. The uptakes in liver and spleen were 12.05%ID /g and 8.97%ID /g as the maximum at 5 min after injection. The clearance in blood and other organs was fast. Except for kidneys and lung, ¹²⁵I –IL-8 was less than 1%ID/ g 24 h after administration. It is concluded that radioiodinated IL-8 is a promising radiopharmaceutical in nuclear medicine, especially for imaging infection. But to enhance the labeling efficiency of radioiodinated IL-8 and to decrease its in vivo deiodination are the subjects necessary to be further investigated.

333

To obtain human sodium/iodide symporter gene cDNA for studying its potential ability as a radioiodide treatment for melanoma, the hNIS gene cDNA was amplified with total RNA from human thyroid tissue by RT-PCR. The hNIS cDNA was inserted into cloning vector pUCm-T and subcloned into eukaryotic expression vector pc-DNA_3. The pc-DNA₃-hNIS and pc-DNA₃ were transduced into melanoma cells (B16) by electroporation, and two cell lines termed B16-A and B16-B respectively were established. The uptake and efflux of iodide was examined in vitro. The three cell lines (B16-A, B16-B, B16) were injected subcutaneously into the right flank of C57 mice. Biodistribution study and tumor imaging were performed when the tumor reached approximately 10mm in diameter. The cloned hNIS cDNA sequence was identical with the published sequence. Two novel cell lines named 16-A containing pc-DNA₃-hNIS and B16-B containing pc-DNA₃ only were established. The resultant cell line B16-A accumulated 17 and 19 times more radioiodide in vitro than B16 and B16-B respectively. The iodide uptake reached the half-maximal level within 10 min, and reached a plateau at 30 min. The efflux of iodide was also rapid (T_1/2eff=10min). The imaging shows in vivo uptake in expected sites including the salivary glands, thyroid, stomach, and hNIS-transduced tumor, whereas the nontransduced tumor was not visualized. The %ID/g of B16-A tumors at 1, 2, 4, 12, and 24h after injection of ¹²⁵I were 12.22±0.71, 10.91±0.72, 8.73±0.99, 1.24±0.29, and 0.19±0.03, respectively, which were significantly higher percentages than those for controlling tumors, p<0.01. However, biologic T_1/2 was about 6 h. Our preliminary data indicate that the transduction of the hNIS gene per se is sufficient to induce iodide transport in melanoma cells both in vitro and in vivo, but T_1/2eff is short.

385

This paper describes new development of the neutron induced prompt gamma-ray analysis (NIPGA) technology in 1988~2003. The pulse fast-thermal neutron activation analysis method, which utilized the inelastic reaction and capture reaction jointly, was employed to measure the elemental contents more efficiently. Lifetime of the neutron generator was more than 10000h and the performance of detector and MCA reached a high level. At the same time, Monte Carlo library least-square method was used to solve the nonlinearity problem in the NIPGA.

386

Since convective boiling or highly subcooled single-phase forced convection in micro-channels is an effective cooling mechanism with a wide range of applications, more experimental and theoretical studies are required to explain and verify the forced convection heat transfer phenomenon in narrow channels. In this experimental study, we model the convective boiling behavior of water with low latent heat substance Freon 113 (R-113), with the purpose of saving power consumption and visualizing experiments. Both heat transfer and pressure drop characteristics were measured in subcooled and saturated concentric narrow gap forced convection boiling. Data were obtained to qualitatively identify the effects of gap size, pressure, flow rate and wall superheat on boiling regimes and the transition between various regimes. Some significant differences from unconfined forced convection boiling were found, and also, the flow patterns in narrow vertical annulus tubes have been studied quantitatively.

444