离子注入在番茄育种中的诱变功效

对番茄N+ 注入诱变效应进行了研究。结果表明,N+ 离子注入对番茄单果重、座果数等性状变幅大且变异率高;而对发芽率和果实的品质性状影响较小。以4×1016 / cm2 和6×1016 / cm2剂量处理,产量提高明显。不同品系、不同性状的最佳诱变剂量略有不同。     

低能氮离子注入对大豆幼苗脂质过氧化的影响

用N+注入丰豆101的种子,采收子叶伸展后24h和96h的幼苗做为试验材料,研究N+注入对其幼苗过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性以及氧化产物丙二醛(MDA)的含量、电解质外渗率的影响。结果表明,在25keV能量下,当N+注量在6.5×1016-7.8×1016N+/cm2时,幼苗的SOD和CAT活性最高。 而POD活性在小于5.2×1016N+/cm2低剂量下, 活性较恒定, 在大于5.2×1016N+/cm2中高剂量下,活性逐渐增大。此外,N+注入还可降低幼苗子叶中的MDA积累量和电解质外渗率,而且在6.5×1016N+/cm2剂量下,幼苗中的MDA含量和电解质外渗率最低。揭示了一定剂量N+注入大豆种子可削弱幼苗脂质过氧化作用以及提高其抗寒性的关系。     

离子注入加工番茄和茄子种子的生物学效应

用6种不同注量的低能氮离子(N+)注入加工番茄87-5种子,出苗率有所降低,但M1代平均单株座果数增加,早熟20d。M2代仍表现出早熟、抗病和较强的生长势。根据两年的试验结果,从加工番茄的早熟性、抗病性、丰产性和品质因素等方面综合分析,采用6×1016cm-2(60次脉冲)的N+注入加工番茄87-5种子,可获得显著的当代生物效应和第二代生物效应。在低能N+注入五叶茄种子的M1代中出现了多纵沟的变异果,形如去皮的柚子,单收此果种子进行种植,在M2代分离的果形中,出现了同时具备抗病、紫红、脐小、果大等优良性状的变异果,最大单果重1.53kg,为育种提供了珍贵材料。     

电子束和离子注入处理鸡冠花种子对当代(Mo)植株生长发育影响的初步研究

利用电子束和氮离子、氢离子注入处理普通鸡冠花干种子,试验结果表明,两种诱变处理均能显著抑制鸡冠花植株的生长、发育,并能有效地诱发花性状变异,变异株率可达0.5%—2%。电子束处理鸡冠花干种子的半致死剂量(LD50)经测定为1.2kGy左右;离子注入处理的半致死剂量随注入离子种类不同而不同,N 注入的半致死剂量(LD50)为1.6×1017/cm2,H 注入的半致死剂量应低于1.6×1016/cm2。鸡冠花干种子电子束处理的适宜剂量为1.5kGy左右,离子注入处理的适宜方法是N 1.6×1016/cm2。同时鸡冠花对高剂量辐照较不敏感,是一种耐强辐照的资源。     

N+注入对甘草幼苗部分耐旱特征效应的研究

植物幼苗主根、侧根及下胚轴的生长和根冠比值的大小是幼苗耐旱的重要特征.对甘草干种子注入能量为25 kev、注量为600×2.6×1013-3600×2.6×1013/cm2的N+,其中1800×2.6×1013/cm2的N+注入量能有效提高甘草6 d幼苗的主根生长和30 d幼苗根冠比干重和鲜重,促进侧根发生;也能明显刺激6 d和30 d幼苗的下胚轴和主根、茎高的生长.该参数可以作为沙漠化地区建立甘草植被发挥离子束注入当代效应的N+辐照的能量、注量的参考参数.在实验注入N+的参数范围内甘草幼苗耐旱特征的应答也表现出"损伤-修复-损伤"效应.     

离子注入在番茄育种中的诱变功效

对番茄N+离子注入诱变效应进行了研究。结果表明 ,番茄单果重、座果数等性状变幅大、变异率高 ;而对发芽率和果实的品质性状影响较小。并以 4× 10 16 N+/cm2 和 6× 10 16 N+/cm2 剂量处理 ,产量提高明显。但不同品系 ,不同性状的最佳诱变剂量略有不同。     

N+注入对甘草叶片腺体和腺体分泌多糖及叶片多糖的影响

甘草叶片上生长有能分泌多糖的腺体,腺体分泌的多糖液累积于腺体头部呈透明"球状",功能叶上所有的腺体均向腺体头部分泌多糖液,枯黄衰老叶上的腺体头部仍然具有完整的呈"球状"的多糖液.对甘草干种子注入总量为4.68×1016/cm2、能量为10-25keV的N 对甘草叶片腺体数、腺体分泌多糖、叶内多糖、叶片总多糖均有刺激效应.其中15 keV的N 注入叶片腺体分泌多糖比对照提高44.1%(P＜0.01);甘草叶面腺体数和腺体分泌多糖呈明显的正相关(r=0.4537,P＜0.1).20keV的N 注入甘草叶片总多糖含量比对照提高31.8%(P＜0.01).这些N 注入甘草干种子的能量、注量参数可供对甘草进行离子束育种时参考.     

Ar+离子辐照对锆4合金耐腐蚀性能的影响

为了研究辐照损伤对锆4合金电化学耐腐蚀性能的影响,使用直线加速器产生单电荷载能Ar+,在液氮温度下辐照样品表面,产生缺陷.然后,测量辐照后锆4合金的电化学极化曲线,使用钝化电流密度作为评定腐蚀性能的指标,分析不同注量Ar+离子辐照对锆4合金钝化电流密度的影响.同时使用透射电子显微镜分析不同注量Ar+辐照下锆4合金损伤层的微观结构.实验结果表明在低离子注量范围内(＜3×1014/cm2),随着辐照量的增加钝化电流密度升高,耐腐蚀性能降低;在中等离子注量范围内(3×1014-1×1016/cm2),随着辐照量的增加钝化电流密度急速下降,耐腐蚀性能显著提高;在高离子注量范围内(1×1016-1×1017/cm2),随着辐照量的增加钝化电流密度又开始增加,耐腐蚀性能再次降低.最后,根据原子碰撞理论对实验结果进行了理论分析.     

低能重离子束注入小麦种子诱导根尖细胞有丝分裂畸变的研究

比较研究了低能重离子束注入小麦干种子和萌动的种子对种子发芽及根尖细胞有丝分裂畸变的影响。结果表明,离子注入对萌动的种子的发芽有明显的影响,而对干种子的发芽影响不明显。在一定剂量范围内(0-6×1016/cm2),N+注入诱导的萌动种子的有丝分裂畸变率略高于干种子,并且随辐射剂量的升高而升高;但超过一定的剂量(>6×1016/cm2),无论是干种子还是萌动种子的有丝分裂畸变率达到一定程度的饱和。就实验结果对N+离子束注入诱变的机理进行了一些探讨。     

85MeV^19F离子辐照α—Al2O3热退火产生的空洞研究

采用正电子湮没寿命技术研究了注量为5.28×1016cm     

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.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

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.     

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.