裂变产物~(147)Pm在体内蓄积的放射遗传毒理效应研究

本研究观察了当机体摄入不同放射量裂变产物~(147)Pm时的体内选择性蓄积部位骨髓细胞染色体畸变、姐妹染色单体互换(SCE)频率和微核率变化的诱发效应。实验结果表明,小剂量~(147)Pm以诱发骨髓细胞染色单体型畸变为主。而随着~(147)Pm摄入量的增加,可出现染色体断裂和易位。~(147)Pm摄入量与骨髓细胞染色体畸变率之间呈半对数直线效应关系,拟合的对数回归方程式为:Y=10.69+1.435InX。同时骨髓畸变细胞与~(147)Pm摄入量之间亦呈现线性关系,拟合的方程式为:Y=9.61+1.24InX,~(147)Pm内污染机体后,可诱发骨髓细胞SCE率和微核的阳性率明显升高,且随着~(147)Pm摄入量的加大,微核阳性率亦进一步增升。     

裂变中离子半径不同的稀土族核素体内滞留诱发突变效应

探讨了裂片中离子半径不同的稀土族核素~(170)Tm,~(152)Eu和~(147)Pm在摄入体内后的滞留差异及其诱发畸变效应。实验观察到,当机体摄入离子半径较大的~(147)Pm时,在肝中蓄积最高;而当摄入离子半径较小的如~(170)Tm或~(152)Eu时,则立即呈现选择性滞留于骨组织中。至于这些稀土族放射性核素对机体诱发突变损伤效应的程度,可随着骨组织累积吸收剂量的增加而诱发骨髓细胞染色体畸变增升。而这些核素诱发骨髓细胞染色体畸变的类型均以染色单体型畸变为主,同时也诱发个别的染色体断裂和易位发生,并可见骨髓细胞中期分裂指数值明显下降。实验还观察到内污染~(170)Tm、~(152)Eu或~(147)Pm时,可在一个细胞中同时诱发有多个畸变发生,这表明不均匀辐照可改变畸变分布。而形成多畸变细胞的程度依次为~(147)Pm>~(152)Eu>~(170)Tm。     

不同辐射体核素在生殖细胞的滞留诱发放射遗传毒理效应比较研究

研究了机体摄入核裂变产物中的纯β辐射体核素~(147)Pm或β,γ混合辐射体核素~(134)Cs后,在生殖系统睾丸中的滞留诱发生殖细胞染色体畸变和精子畸形效应。实验结果拟合的~(147)Pm在睾丸内滞留方程为:R(t)=0.1872×e~(-0.0066t)其滞留半减期长达105天,可见~(147)Pm在睾丸中呈持续性蓄积,较难转移。至于~(134)Cs在睾丸中拟合的滞留方程为:R(t)=0.0045×e~(-0.133t),其滞留半减期只有5.2天,表明~(134)Cs在睾丸中的转移是较快的。实验发现,受~(147)Pm或~(134)Cs内污染时,均可诱发精原细胞染色体畸变,且以染色单体型畸变为主,而染色体型畸变的断片或易位较少呈现。同时也观察到~(147)Pm对初级精母细胞的遗传损伤效应,可产生染色体断片和易位,出现多价体。~(147)Pm和~(134)Cs所诱发的精子畸形主要都是无钩精子,只是~(147)Pm在诱发精子畸形的程度上要高于~(134)Cs。鉴于~(134)Cs在睾丸中的滞留程度远比~(147)Pm为低,且其滞留半减期亦远低于~(147)Pm,其所致的累积吸收剂量亦就小于~(147)Pm。所以,~(134)Cs摄入机体后所诱发的精原细胞染色体畸变和精子畸形等放射遗传毒理效应,亦较~(147)Pm为低。     

不同辐射体核素在生殖细胞的滞留诱发放射遗传毒理效应比较研究

研究了机体摄入核裂变产物中的纯β辐射体核素~(147)Pm或β,γ混合辐射体核素~(134)Cs后,在生殖系统睾丸中的滞留诱发生殖细胞染色体畸变和精子畸形效应。实验结果拟合的~(147)Pm在睾丸内滞留方程为:R(t)=0.1872×e~(-0.0066t)其滞留半减期长达105天,可见~(147)Pm在睾丸中呈持续性蓄积,较难转移。至于~(134)Cs在睾丸中拟合的滞留方程为:R(t)=0.0045×e~(-0.133t),其滞留半减期只的5.2天,表明~(134)Cs在睾丸中的转移是较快的。实验发现,受~(147)Pm或~(134)Cs内污染时,均可诱发精原细胞染色体畸变,且以染色单体型畸变为主,而染色体型畸变的断片或易位较少呈现。同时也观察到~(147)Pm对初级精母细胞的遗传损伤效应,可产生染色体断片和易位,出现多价体。~(147)Pm和~(134)Cs所诱发的精子畸形主要都是无钩精子,只是~(147)Pm在诱发精子畸形的程度上要高于~(134)Cs.鉴于~(134)Cs在睾丸中的滞留程度远比~(147)Pm为低,且其滞留半减期亦远低于~(147)Pm,其所致的累积吸收剂量亦就小于~(147)Pm。所以,~(134)Cs摄入机体后所诱发的精原细胞染色体畸变和精子畸形等放射遗传毒理效应,亦较~(147)Pm为低。     

裂变中离子半径不同的稀土族核素体内滞留诱发突变效应

探讨了裂片中离子半径不同的稀土族核素~(170)Tm,~(152)Eu和~(147)Pm在摄入体内后的滞留差异及其诱发畸变效应。实验观察到,当机体摄入离子半径较大的~(147)Pm时,在肝中蓄积最高;而当摄入离子半径较小的如~(170)Tm或~(152)Eu时,则立即呈现选择性滞留于骨组织中。至于这些稀土族放性核素对机体诱发突变损伤效应的程度,可随着骨组织累积吸收剂量的增加而诱发骨髓细胞染色体畸变增升。而这些核素诱发骨髓细胞染色体畸变的类型均以染色单体型畸变为主,同时也诱发个别的染色体断裂和易位发生,并可见骨髓细胞中期分裂指数值明显下降。实验还观察到内污染~(170)Tm、~(152)Eu或~(147)Pm时,可在一个细胞中同时诱发有多个畸变发生,这表明不均匀辐照可改变畸变分布。而形成多畸变细胞的程度依次为~(147)Pm>~(152)Eu>~(170)Tm。     

滞留在组织中的钷-147诱发骨髓细胞致突变损伤的剂量效应关系研究

探讨了裂变产物~(147)Pm单次或连续多次摄入体内时的蓄积特性和诱发骨髓细胞突变效应 的相互关系。当~(147)Pm单次摄入机体后,早期呈选择性沉积于肝,5d后在骨髓中的沉积增升至首位,且呈表面型沉积。观察到可诱发骨髓细胞染色体畸变的发生,其畸变程度随体内摄入~(147)Pm的放射量的加大而相应增高。至于在~(147)Pm连续5d摄入机体后,从实验观察所得的滞留方程的慢相滞留半减期来见,要长达1155d之久,又从排除方程的慢组分半排期来看,也有121.58d。这些数据提示~(147)Pm摄入机体后,其自然排除极缓慢,有80％以上的~(147)Pm滞留在组织中,尤其在骨组织中呈选择性滞留,因而可引起骨髓细胞染色体畸变率的明显增升,值得指出的是,无论从~(147)Pm单次或连续多次摄入体内所诱发的畸变类型来看,大多是属于单体型的。     

单次或多次滞留骨组织的^147Pm诱发骨髓细胞突变损伤的量效关系

探讨了当~(147)Pm单次或连续多次摄入体内时,在骨组织的滞留并诱发骨髓细胞突变损伤的剂量效应关系。观察到~(147)Pm在单次或多次内污染时,都在骨组织中呈选择性滞留,并可诱发骨髓细胞染色体发生畸变,其畸变程度可随体内摄入~(147)Pm放射性活度的加大而相应增高,呈现良好的剂量效应关系。无论从单次或连续多次~(147)Pm摄入体内所诱发的染色体畸变类型来看,大多属于单体型。     

内污染不同辐射体核素在骨组织的滞留诱发骨髓细胞突变效应比较研究

比较了当机体摄入不同辐射体核素~(134)Cs或~(147)Pm后,在骨组织中的滞留特性诱发体细胞中骨髓细胞的染色体畸变和PCE的微核形成效应。研究表明,机体摄入~(134)Cs后在持续7周时间的观察中,发现其在骨组织中的滞留可随时间的增长而迅速下降,拟合的滞留方程为:R(t)=0.0029e~(-0.121t),可见在骨中的滞留半减期只有5.73d。而~(147)Pm在相应实验阶段中在骨组织的滞留量则随观察时间的延长而呈持续的选择性蓄积,且沉积后的转移极慢,拟合的滞留方程为;R(t)=115.7977~(-0.0002t)-55.0212e~(-0.7516t),可见在骨中的滞留半减期竟长达3465d之久。所以~(134)Cs在骨组织的相对滞留量和累积吸收剂量贡献都远低于~(147)Pm。~(134)Cs或~(147)Pm均可诱发骨髓细胞染色体畸变和PCE的微核形成效应。但在比较相应放射性活度时,~(134)Cs所诱发的骨髓细胞染色体畸变率和PCE的微核形成率效应,都较~(147)Pm为低。     

内污染不同辐射体核素在骨组织的滞留诱发骨髓细胞突变效应比较研究

比较了当机体摄入不同辐射体核素~(134)Cs或~(147)Pm后,在骨组织中的滞留特性诱发体细胞中骨髓细胞的染色体畸变和PCE的微核形成效应。研究表明,机体摄入~(134)Cs后在持续7周时间的观察中,发现其在骨组织中的滞留可随时间的增长而迅速下降,拟合的滞留方程为:R(t=0.0029e~(-0.121t),可见在骨中的滞留半减期只有5.73d。而~(147)Pm在相应实验阶段中在骨组织的滞留量则随观察时间的延长而呈持续的选择性蓄积,且沉积后的转移极慢,拟合的滞留方程为;R(t)=115.7977e~(0.0002t)-55.0212e~(-0.7516t),可见在骨中的滞留半减期竟长达3465d之久。所以~(134)Cs在骨组织的相对滞留量和累积吸收剂量贡献都远低于~(147)Pm。~(134)Cs或~(147)Pm均可诱发骨髓细胞染色体畸变和PCE的微核形成效应。但在比较相应放射性活度时,~(134)Cs所诱发的骨髓细胞染色体畸变率和PCE的微核形成率效应,都较~(147)Pm为低。     

裂片~(147)Pm在肝及胚肝中的滞留诱发肝及胚肝细胞突变效应比较研究

考虑到肝脏是~(147)Pm污染早期滞留和作用的主要靶器官,本研究对~(147)Pm在肝及胚肝中的滞留和诱发肝及胚肝细胞染色体畸变效应进行了对比观察。发现当~(147)Pm摄入机体后,在再生肝中的滞留量要比在同期胚肝中高出700倍之多,估算在再生肝中的累积吸收剂量为2.87Gy,而在胚肝中只有0.004Gy。这与胎盘的屏障作用密切相关,起到了对胚胎细胞的保护作用。在此条件下~(147)Pm诱发再生肝细胞的染色体畸变率为50.2％,而对胚肝细胞则为28.3％,二者之差不到一倍。由此可见胚肝细胞对~(147)Pm的辐射敏感性要比再生肝细胞高得多。至于从~(147)Pm对再生肝及胚肝细胞所诱发的染色体畸变类型来看,则都以染色单体型畸变为主。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.