STUDY ON MODERATORS OF SMALL－SIZE NEUTRON RADIOGRAPHY INSTALLATIONS WITH NEUTRON TUBE AS SOURCE

ＳＴＵＤＹ　ＯＮ　ＭＯＤＥＲＡＴＯＲＳ　ＯＦ　ＳＭＡＬＬ－ＳＩＺＥ　ＮＥＵＴＲＯＮ　ＲＡＤＩＯＧＲＡＰＨＹ　ＩＮＳＴＡＬＬＡＴＩＯＮＳ　ＷＩＴＨ　ＮＥＵＴＲＯＮ　ＴＵＢＥ　ＡＳ　ＳＯＵＲＣＥＭａＷｅｉｃｈａｏ（马维超）；ＺｈｏｕＭｉｎｇｄａ（周明达）...     

STUDY ON RESIDUES OF ~（14）C－FENITROTHION IN MODEL RICE－FISH ECOSYSTEM AND FIELD RICE－FISH ECOSYSTEM

ＳＴＵＤＹＯＮＲＥＳＩＤＵＥＳＯＦ~（１４）Ｃ－ＦＥＮＩＴＲＯＴＨＩＯＮＩＮＭＯＤＥＬＲＩＣＥ－ＦＩＳＨＥＣＯＳＹＳＴＥＭＡＮＤＦＩＥＬＤＲＩＣＥ－ＦＩＳＨＥＣＯＳＹＳＴＥＭＺｈａｎｇＺｈｏｎｇｌｉａｎｇ（张仲良）；ＷａｎｇＨｕａｘｉｎ（王化新）；Ｇ?..     

NASOPHARYNGEAL CARCINOMA RADIOSENSITIVITY PREDICTION BY CYTOKINESIS－BLOCK MICRONUCLEUS ASSAY

ＮＡＳＯＰＨＡＲＹＮＧＥＡＬ　ＣＡＲＣＩＮＯＭＡ　ＲＡＤＩＯＳＥＮＳＩＴＩＶＩＴＹ　ＰＲＥＤＩＣＴＩＯＮ　ＢＹ　ＣＹＴＯＫＩＮＥＳＩＳ－ＢＬＯＣＫ　ＭＩＣＲＯＮＵＣＬＥＵＳ　ＡＳＳＡＹＹａｎｇＸｉｎｇ（杨星）；ＳｈｉＪｉａｎｈｕｉ（史剑慧）ａｎｄＣｈ...     

MEASUREMENT OF NEUTRON SPECTRA FROM THICK Be TARGET BOMBARDED WITH DEUTERONS

ＭＥＡＳＵＲＥＭＥＮＴＯＦＮＥＵＴＲＯＮＳＰＥＣＴＲＡＦＲＯＭＴＨＩＣＫＢｅＴＡＲＧＥＴＢＯＭＢＡＲＤＥＤＷＩＴＨＤＥＵＴＥＲＯＮＳＷａｎｇＸｉａｏｚｈｏｎｇ（王效忠）；ＢａｉＸｉｘｉａｎｇ（白希祥）；ＬｉＡｎｌｉ（李安利）；ＬｉｕＷｅｉｐｉｎｇ（柳...     

STUDY ON BEHAVIOUR OF CR FORMULATION OF THIOBENCANB IN A MODEL PADDY FIE

ＳＴＵＤＹＯＮＢＥＨＡＶＩＯＵＲＯＦＣＲＦＯＲＭＵＬＡＴＩＯＮＯＦＴＨＩＯＢＥＮＣＡＮＢＩＮＡＭＯＤＥＬＰＡＤＤＹＦＩＥＬＤＳｕｎＪｉｎｈｅ（孙锦荷）；ＬｉＸｉｎｇｍｉｎｇ（李兴明）；ＣｈｅｎＺｉｙｕａｎ（陈子元）ａｎｄＺｈａｎｇＱｉｎｚｈｅｎｇ（张...     

MEASUREMENTS OF TOTAL CROSS SECTIONS FOR K－SHELL IONIZATION BY ELECTRON BOMBARDMENT

ＭＥＡＳＵＲＥＭＥＮＴＳＯＦＴＯＴＡＬＣＲＯＳＳＳＥＣＴＩＯＮＳＦＯＲＫ－ＳＨＥＬＬＩＯＮＩＺＡＴＩＯＮＢＹＥＬＥＣＴＲＯＮＢＯＭＢＡＲＤＭＥＮＴＬｉＪｉｎｇｗｅｎ（李景文）；ＤｏｎｇＺｈｉｑｉａｎｇ（董志强）；ＺｅｎｇＸｉａｎｔａｎｇ（曾宪堂），Ｈ...     

RADIOIMMUNOTOXICOLOGICAL EFFECT OF ENRICHED URANIUM ON CENTRAL AND PERIPHERAL IMMUNE CELLS AND THE PROTECTIVE ACTION OF IL－1 AND IL－2

ＲＡＤＩＯＩＭＭＵＮＯＴＯＸＩＣＯＬＯＧＩＣＡＬＥＦＦＥＣＴＯＦＥＮＲＩＣＨＥＤＵＲＡＮＩＵＭＯＮＣＥＮＴＲＡＬＡＮＤＰＥＲＩＰＨＥＲＡＬＩＭＭＵＮＥＣＥＬＬＳＡＮＤＴＨＥＰＲＯＴＥＣＴＩＶＥＡＣＴＩＯＮＯＦＩＬ－１ＡＮＤＩＬ－２￥ＺｈｕＳｈｏｕｐｅ...     

RADIONUCLIDES IN NOODLES AND BREAD CONSUMED IN HONG KONG

ＲＡＤＩＯＮＵＣＬＩＤＥＳ　ＩＮ　ＮＯＯＤＬＥＳ　ＡＮＤ　ＢＲＥＡＤ　ＣＯＮＳＵＭＥＤ　ＩＮ　ＨＯＮＧ　ＫＯＮＧＫＮＹｕ（余君岳）ａｎｄＳＹＭａｏ（茅瑞恩）（ＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓａｎｄＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅ，ＣｉｔｙＵｎｉ...     

A DYNAMIC FOOD CHAIN MODEL FOR HONG KONG BASED ON RADFOOD MODEL AND BIRCHALL－JAMES ALGORITHM

Ａ　ＤＹＮＡＭＩＣ　ＦＯＯＤ　ＣＨＡＩＮ　ＭＯＤＥＬ　ＦＯＲ　ＨＯＮＧ　ＫＯＮＧ　ＢＡＳＥＤ　ＯＮ　ＲＡＤＦＯＯＤ　ＭＯＤＥＬ　ＡＮＤ　ＢＩＲＣＨＡＬＬ－ＪＡＭＥＳ　ＡＬＧＯＲＩＴＨＭＫ．Ｎ．Ｙｕ（余君岳）；Ｋ．Ｐ．Ｎｇ（吴国斌）；Ｔ．Ｃｈｅｕｎｇ（...     

PREPARATION OF BONE TUMOR THERAPEUTIC RADIOPHARMACEUTICALS ^153 Sm—EDTMP

ＰＲＥＰＡＲＡＴＩＯＮ　ＯＦ　ＢＯＮＥ　ＴＵＭＯＲ　ＴＨＥＲＡＰＥＵＴＩＣ　ＲＡＤＩＯＰＨＡＲＭＡＣＥＵＴＩＣＡＬＳ　~（１５３）Ｓｍ－ＥＤＴＭＰＬｕｏＳｈｕｎｚｈｏｎｇ（罗顺忠）；ＰｕＭａｎｆｅｉ（蒲满飞）；ＱｉａｏＪｉａｎ（谯健）；ＬｉｕＺｈｏｎ?..     

Reactor Neutron Fluctuation Simulator Using Pulsed Neutron Source

The fission phenomena in a multiplying medium are simulated by neutron bursts in a non-multiplying medium produced by a pulsed neutron source. To simulate the chain reaction, the pulsed neutron source is triggered by neutronic signals from a detector installed in that medium. The kinetic parameters can be changed at will by regulating the detector sensitivity, the system medium and the burst yield of the pulsed neutron source.

This simulator has been tested on experiments with Rossi-a, Feynman-a and pulse die away methods and is also applied to the experiments with waiting time method and observation of neutron families to verify the recently developed theory in this domain.

The results prove that, in principle, the number of neutrons in this simulator can represent the probabilistic nature of the neutrons in a multiplying medium described by one point model. Furthermore, the newly developed theory for reactor parameter measurement has been substantiated with use of the simulator.

The simulator in its present form is restricted in applicable range to keff=0–0.66 by limitations in the performance of the pulsed neutron source used.     

Bystander effects induced by medium from carbon-ion irradiated human cancer cells

The bystander effects induced by medium from human hepatoma SMMC-7721 and adenocarcinoma F56 cells irradiated with carbon ions were investigated. It was found that the survival fraction （SF） of the irradiated cells decreased exponentially along with the increased dose. SMMC-7721 cells were more radiosensitive than F56 cells. The plating efficiency （PE） of the non-irradiated cells treated with irradiated conditioned medium （ICM） was obviously lower than the PE of control cells for SMMC-7721 cells but not for F56 cells. Moreover, the reduced PE and SF by ICM treatment were more significant for IGy irradiation than for 6Gy irradiation on SMMC-7721 cells, These results suggest that the irradiated cells can secrete factor（s） into medium that is cytotoxic to bystander non-irradiated cells. The bystander effects are dependent on cell genotype presented at the time of irradiation and radiation dose, This makes impact on the precise estimation of the effects of radiation and tumor radiotherapy,     

H1299旁效应细胞对X-射线辐射的适应性与TGF-β1通路相关

本研究探索辐射诱导人非小细胞肺癌H1299旁效应细胞的适应性反应及TGF-β1通路在其中的作用。采用培养液转移法得到辐射诱导的旁效应细胞,用克隆形成实验检测旁效应细胞受照射后的适应性反应,用Western Blotting检测旁效应细胞中SOD2的表达变化。结果发现:用条件培养液培养H1299旁效应细胞,并不影响细胞的克隆存活率;但是细胞经1 h和18 h未照射条件培养液培养后再接受2Gy的X-射线照射,其细胞存活率较培养于新鲜培养液的细胞受照后的存活率分别增加了12%和38%,经1 h和18 h照射条件培养液培养后的细胞再接受2Gy的X-射线照射,其细胞存活力在此基础上又分别增加了10%;当在照前用TGF-βR1抑制剂SB431542处理信号细胞后,旁效应细胞的适应性反应不再发生;而将SB431542直接加入条件培养液中,并未影响1 h条件培养液诱导的适应性,但是用含有SB431542的18 h未照射和照射条件培养液培养过的旁效应细胞经2 Gy照射后,其克隆存活率较未加SB431542组分别降低了28%和18%,18 h未照射和照射条件培养液组间差异却增大至24%;旁效应细胞经照射条件培养液培养3 h或5 h后其SOD2表达下降。以上结果表明经条件培养液培养后旁效应细胞对X-射线照射产生了适应性反应,照射条件培养液与未照射条件培养液相比,进一步增加了这种适应性,并且TGF-β1信号通路对该适应性有重要调控作用,而SOD2可能未参与这个过程。     

~(125)I-T_4和~(125)I-T_3放射性比活度测定

本文介绍了应用自身置换法和放射免疫分析法测定~(125)I-T_4和~(125)I-T_3的比活度,获得了比较准确的结果。并研究了放射免疫分析中不同比活度的标记抗原对灵敏度的影响。     

Modified-Levermore–Pomraning equation: Its derivation and its limitations

A transport equation for the mean flux in spatially random media is derived, and is referred to as Modified-Levermore–Pomraning equation (M-L–P). It differs from the conventional L–P equations in that |μ| in the latter is replaced by μ in M-L–P. It is shown that when scattering is present the L–P equations are always incorrect in the sense there is not any special situation in which they can lead to an exact result. In particular they always predict the relaxation lengths of the spatial modes incorrectly. On the other hand, the M-L–P equations are exact when the flux at the origin is deterministic, as in some special cases such as half-infinite medium, and infinite medium with a localized source at the origin, when the density of the medium is spatially random. However, the M-L–P equations become approximate when the medium is a finite slab because of the right boundary condition. But the relaxation rates of the spatial modes are always calculated exactly even in finite slab. The nature of approximation inherent in the M-L–P is elucidated by comparison with the exact “stochastic transition matrix formalism” developed earlier in two-stream transport.     

Computational tracking of BN-600 operation

Computational tracking of BN-600 operation is described. The high quality of computational tracking is largely due to the nature of a fast reactor, in this case BN-600. Unlike reactors with a thermal neutron spectrum, in a fast reactor, because the prompt and delayed fission neutrons as well as the absorbed neutrons are almost in the same energy range as the fast neutrons, a computational cell can be confidently homogenized and the reactor is strongly coupled to the neutron field. These are the reasons why the behavior of the reactor can be successfully predicted by means of computational programs which are based on the diffusion approximation neglecting the anisotropy of the interaction of the neutrons and the heterogeneity of the medium.     

桥本氏甲状腺炎核素显像特点与功能测定的临床评价

通过对61例桥本氏甲状腺炎核素显像特点及功能测定分析，将桥本氏甲状腺炎分为5种类型，即分布粗糙不均型、弥漫甲肿型、合并甲亢型、结节型、大致正常型。对各型影像特点及血清放免功能测定结果分析可知，桥本氏甲状腺炎尽管显像特点及功能检查表现多样，但只要认真分析，使用多种核医学手段，结合临床症状及体征，可以作出初步诊断和鉴别诊断。     

The spatial dependence of the energy spectrum of slowing down particles—I. Applications to reactor physics and atomic sputtering

An extensive investigation has been carried out of the energy spectrum of particles in a half-space irradiated with a monoenergetic beam, i.e. the classical albedo problem but extended to include energy dependence. Slowing down is described by elastic scattering and various models for dealing with the anisotropic nature of the scattering, especially important for mass ratios A ? 1, are proposed. To obtain analytical solutions we have concentrated on the case of an energy independent cross-section, when the Laplace transformed equation can be reduced to an effective one-speed problem with isotropic scattering. The equation is solved by the Wiener-Hopf technique and explicit expressions are obtained for the angular distribution of emitted particles and the spatial variation of the spectrum within the medium. We concentrate on surface phenomena and have computed the emergent current and the energy reflection coefficient, γ, for mass ratios in the range 0.1 ? A ? 10. In accordance with expectation, the leakage current for large A is peaked near the source energy but becomes progressively closer to the infinite medium, E^?1, form as A decreases. A detailed calculation of γ shows that its value for hard-sphere scattering follows closely the results obtained by Sigmund who used a modified infinite medium approach. An extension of the method to include the effects of anisotropic scattering in the C.M. system is discussed and illustrated.Finally, we calculate the energy deposited by the infinite medium approximation of Sigmund and are able to assess its accuracy by comparison with the exact half-space results. We find that, for hard-sphere scattering, the infinite medium values of γ are always less than the exact values. However, for A < 1, the error never exceeds 3.5%. It becomes progressively worse as A increases.     

Bystander effect in human hepatoma HepG2 cells caused by medium transfers at different times after high-LET carbon ion irradiation

Although radiation-induced bystander effects have been well documented in a variety of biological systems, whether irradiated cells have the ability to generate bystander signaling persistently is still unclear and the clinical relevance of bystander effects in radiotherapy remains to be elucidated. This study examines tumor cellular bystander response to autologous medium from cell culture irradiated with high-linear energy transfer (LET) heavy ions at a therapeutically relevant dose in terms of clonogenic cell survival. In vitro experiments were performed using human hepatoma HepG2 cell line exposed to 100 keV/μm carbon ions at a dose of 2 Gy. Two different periods (2 and 12 h) after irradiation, irradiated cell conditioned medium (ICCM) and replenished fresh medium were harvested and then transferred to unirradiated bystander cells. Cellular bystander responses were measured with the different medium transfer protocols. Significant higher survival fractions of unirradiated cells receiving the media from the irradiated cultures at the different times post-irradiation than those of the control were observed. Even replenishing fresh medium for unirradiated cells which had been exposed to the ICCM for 12 h could not prevent the bystander cells from the increased survival fraction. These results suggest that the irradiated cells could release unidentified signal factor(s), which induced the increase in survival fraction for the unirradiated bystander cells, into the media sustainedly and the carbon ions triggered a cascade of signaling events in the irradiated cells rather than secreting the soluble signal factor(s) just at a short period after irradiation. Based on the observations in this study, the importance of bystander effect in clinical radiotherapy was discussed and incorporating the bystander effect into the current radiobiological models, which are applicable to heavy ion radiotherapy, is needed urgently.