A new nuclide 238Th has been produced via multinucleon transfer reaction by 60 MeV/u 18O ion irradiation of the natural uranium. The thorium was radiochemically separated from the mixture of uranium and reaction products. The activity of thorium was measured by using an HPGe detector and a planar HPGe detector. The 238Th has been identified for the first time by measuring the growth and decay of the γ-rays from its daughter 238Pa. The half-life of 238Th was determined to be 9.4±2.0 min. In addition, a new γ-ray of 89.0±0.3keV with T1/2=8.9±1.5min was found in the γ spectrum gated with X-rays of Pa and assigned to 238Th β- decay based on measurements of transition energy and half life.
Vol.10, No.2
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685
Research article 01 Mar 1999
XU Yanbing，YUAN Shuanggui，YANG Weifan，LI Zongwei，MA Taotao，XIONG Bing，HE Jianjun
keyword：Multinucleon transfer reaction；Chemical separation；New nuclide；Synthesis and identification；
Research article 01 Mar 1999
QI Lanying，JIANG Xiaohua，ZHENG Jian，WANG Yichao，LI Sanwei，LI Chaoguang，ZHANG Wenhai，ZHENG Zhijian
Making use of disk targets composed of several peculiar materials (foam Au, foam C8H8) and hohlraum with a special structure, experiments have been done at "Xing Guang - II" laser facility, which study the characteristics of hot electrons and the related nonlinear processes such as Stimulated Raman Scattering (SRS), Two Plasma Decay (TPD), Stimulated Brillouin Scattering (SBS), etc.
keyword：Foam Au and Foam C8H8；Hot electron；Nonlinear Processes；
Research article 01 Mar 1999
SHI Miangon，TANG Ayou，ZHU Zhousen，YANG Beifang，MIAO Jingwei
Measurements of zero-degree breakup fragment energy distribution from the Coulomb-Explosions of 1.50965 MeV HD+ ion micro-cluster beam are reported. Mean value of the internuclear separation of HD+ is found to be 0.125±0.003 nm. A set of high-resolution experimental arrangement and improvement of the Van-de-Graaff accelerator are described briefly.
keyword：HD+；Internuclear separation；Micro-cluster；
Research article 01 Mar 1999
YANG Jiamin，DING Yaonan，ZHENG Zhijian，YI Rongqing，SUN Kexu，CUI Mingqi，CUI Congwu，ZHU Peiping，CHEN Zhenlin，LI Chaoguang，WANG Yaomei
Tansmission grating spectrometers are extensively used to measure abso-lute X-ray spectra in a photon-energy range below 1000 eV. The transmission grating, as its dispersive element, must be calibrated to obtain its diffraction efficiencies. Cali-brations of absolute diffraction efficiencies of the transmission grating at photon energy of 844 eV have been carried out on Beijing Synchrotron Radiation Facility. With the aid of grating model, all of the grating structure parameters have been determined and the absolute diffraction efficiencies in a photon-energy range below 2000 eV have also been calculated and discussed.
keyword：Synchrotron radiation；Transmission grating；Diffraction efficiency；
Research article 01 Mar 1999
ZHANG Chunxiang，LUO Daling
Inactivation cross sections for haploid yeast cell strain 211a have been calculated as 1-hit detector based on the track theory in an extended target mode and a numerical calculation of radial dose distribution. In the calculations, characteristic dose D0 is a fitted parameter which is obtained to be 42 Gy, and "radius" of hypo-thetical target α0 is chosen to be 0.5µm which is about the size of nucleus of yeast cells for obtaining an overall agreement with experimental cross sections. The results of the calculations are in agreement with the experimental data in high LET (linear energy transfer) including the thindown region.
keyword：Inactivation cross section；Haploid yeast cell；Yeast cell；Radial dose distribution；
Research article 01 Mar 1999
LIU Xiaowei，WEN Guanghao，LI Mianfeng
The single beam dose profiles of Leksell Gamma Unit are simulated and the results are compared with the experimental results of ELEKTA. The effect of diameter of cylinder source on the dose profile is also studied and the yielded results show that there are not much difference of the dose profiles between a point source and cylinder source when diameter is less than 1 mm.
keyword：Monte Carlo simulation；Gamma knife；Dose profile；
Research article 01 Mar 1999
YANG Zhanshan，ZHU Shoupeng，YANG Shuqin
Effects of pretreatment of mouse with low doses of internally deposited 147Pm on the mutagenicity of both the bone marrow lymphocytes and the spermato-blasts induced by subsequent high dose of internally deposited 147Pm were studied. Kunming male mice were injected from the tail vein with low doses of 147Pm(NO3)3 of 0.37, 3.7 and 37 Bq/g body weight. Three days later the mice were injected with a high dose of 147Pm(NO3)3 of 18.5 kBq/g body weight. The animals were sacrificed at 24 h after the high dose injection. The results show that the bone marrow lymphocytes and the spermatoblasts pre-exposed in vivo to low doses of 147Pm can produce an adaptive response. The radioadapted cells had a resistance to the mutagenicity induced by the subsequent high dose of 147Pm, that is, the proportion of both the bone marrow lymphocytes containing micronuclei and the sperm shape abnormalities was significantly lower than those for the pure high dose group (P < 0.01). In addition, the induction of the adaptive response of the cells possesses the different dose ranges for the different biological parameters. The 147Pm dose ranges of the adaptive response are 0.37~3.7 and 0.37~37 Bq/g body weight for the frequency of micronucleated bone marrow lymphocytes and abnormal sperms, respectively.
keyword：Micronucleus；Adaptive response；147Pm；Sperm shape abnormalities；
Research article 01 Mar 1999
ZHANG Yi，OUYANG Zhenqian，HU Jun，CHEN Shengfu，LI Minqian，ZHAO Hui，QIAN Ruolan
The chromatin folding patterns in air and liquid were studied by atomic force microscopy (AFM). A gentle water-air interface method was adopted to spread chromatin from interphase nucleus of chicken erythrocyte. The chromatin was absorbed on APS-mica surface and studied with AFM. Beads-on-a-string were observed and many higher-order structures such as superbeads with dimensions 40~60 nm in diameter and 4~7 nm in height were found to string together to make chromatin fibers. When sample spreading and absorbing time were shortened, higher-order chromatin fibers with 60~120 nm in width were observed in air as well as under water environment. These chromatin structures may reflect chromatin folding patterns in the living cells.
keyword：Atomic force microscopy；Chromatin folding patterns；Chicken erythrocytes；
Research article 01 Mar 1999
SONG Shiping，TANG Guozhong，LI Bin
A sensitive, specific, noncompetitive, sandwich-type radioimmunoassay for carcinoembryonic antigen (CEA) has been developed in our laboratory, which can be performed conveniently. The assay involves two monoclonal antibodies, selected for high affinity and specificity and also for reaction against antigenic sites on CEA that are distal from each other. One of these antibodies was labeled with 125I and the other was conjugated covalently to biotin. Polystyrene tubes were conjugated covalently to avidin. These tubes represent a rapid, simple method for separating the CEA-bound antibody from the free antibody. The biotin-antibody-CEA-125I-labeled antibody complexes bind to the tubes and CEA concentration is directly related to counts per minute. This assay can detect the CEA at a concentration of 0.22 μg/L in serum.
keyword：Carcinoembryonic antigen(CEA)；Immunoradiometric assay(IRMA)；Biotin-avidin system(BAS)；
Research article 01 Mar 1999
GUO Jiangfeng，SUN Jinhe，PING Xiaofei，YE Qingfu
When individual microorganisms were used to release bound pesticide residues, it was ussually not take into full account whether the autoclaving method could lead to the release of bound residues. The soil containing bound 14C-chlorsulfuron residues was treated with an autoclave in this study. The results reveal that the bound 14C-chlorsulfuron residue can be released from the soil when treated with the autoclave and the release rate can be remarkably enhanced by adding water into the soil when subjected to such treatment. A TLC analysis showed that the released 14C-residue was one of the degraded products of 14C-chlorsulfuron. After derivatization and analysis using the GC-MS, the released 14C-residue was tentatively identified as 2-amino-4-hydroxyl-6-methyl-1,3,5-triazine.
keyword：14C-chlorsulfuron；Bound residue；Release；Autoclave；Formation mechanism；
Research article 01 Mar 1999
SHEN Dingyu，CHEN Jian，ZHAO Qiang，WANG Xuemei
The importance of point defects in semiconductor and function materials has been studied in detail, but effective means for detecting point defects has not been available for a long time. The end of range defects in Si, produced by 140 keV Ge+ implantation, were investigated as detectors for measuring the interstitial concentration created by 42 keV B+ implantation. The concentration of interstitial resulting from the B+ implantation and the behavior of the interstitial flux under different annealing condition were given. The enhanced diffusion in the boron doped EPI marker, resulting from mobile non-equilibrium interstitials was demonstrated to be transient. Interstitial fluxes arising from processing can be detected by transient enhanced diffusion (TED) of doped marker layers as well.
keyword：Ion implantation；Detector；Dislocation loop；Point defect；Marker layer；Anomalous diffusion；
Research article 01 Mar 1999
LIU Yonghao，LI Deming，CHEN Maobai，LU Xiangshun
The existing injection system of the SMCAMS (super-sensitive minicyclotron accelerator mass spectrometer) is described together with the discussion of its disadvantages exposed after having been operating for five years, which provides a basis for consideration of improvements to the injection system. An optimized injection system with an analytical magnet added prior to the minicyclotron has been proposed and calculated.
keyword：X-rays；Space charge effects；Minicyclotron；Three-diaphragm lens；Image magnification；
Research article 01 Mar 1999
LI Guisheng，ZHANG Tianmei，LI Zongwei，SU Youwu，ZHANG Shumin
Fluence rates and angular distributions of the neutron emitted by 75 MeV/u 12C-ion bombardment on thick Be and Au targets have been measured by means of the threshold detector activation method. Based on that, the neutron yields, emission rates in the forward direction and neutron dose equivalent rate distributions were deduced.
keyword：Neutron；Yield；Fluence rate；Dose equivalent rate；Intermediate energy heavy ion reaction；
Research article 01 Mar 1999
YU Shaoning，BAO Borong
The synergistic extraction of U(VI) and Th(IV) from nitric acid solution by HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) and TBP (tributylphosphate ) in toluene was studied. The extraction ability of HBMPPT for U(VI) and Th(IV) was not so high, but when a little TBP was added in, the ability to extract U(VI) and Th(IV) was improved. The extracted complexes may be presented as UO2NO3·BMPPT·TBP and UO2(BMPPT)2·TBP for U(VI), and Th(NO3)3·BMPPT·TBP and Th(NO3)2 (BMPPT)2·TBP for Th(IV), respectively, in the synergistic extraction system. The synergistic effect of HBMPPT and TBP makes the separation coefficient of U(VI) /Th(IV) or U(VI)/Eu(III) reach a high value.
keyword：Synergistic extraction；U/Th separation；
