中能氮离子束辐照小麦种子产生自由基的研究

用ＥＳＲ波谱术研究了室温下中能氮离子辐照小麦种子产生的自由基，发现氮离子贯穿和注入小麦种子产生的自由基浓度随剂量的变化具有不同的特征。对氮离子贯穿小麦种子产生的自由基浓度随剂量率的变化规律也进行了研究。     

纳秒级强脉冲电子束与Ar~＋离子束辐照作物种子后自由基产额的变化

应用多极板放电室产生的纳秒级强脉冲电子束与Ａｒ~＋离子束辐照蕃茄、黄瓜、辣椒和小麦的种子，分别测定辐照种子中的自由基产额，统计胚根根尖细胞中的染色体畸变频率和种子的萌发能力，藉以比较两种不同脉冲处理的辐照效果。实验发现：辐照处理时间的长短与自由基产额、染色体畸变率以及种子的萌发能力密切相关。辐照处理时间长，自由基产额高，染色体畸变率高，萌发生长能力低。四种作物种子的重复实验证明，电子脉冲的辐射效应明显强于Ａｒ~＋离子脉冲。     

纳秒级强脉冲电子束与Ar^＋离子束辐照作物种子后自由…

应用多极板放电室产生的纳秒级强脉冲电子束与Ａｒ＾＋离子束辐照蕃茄、黄瓜、辣椒和小麦的种子，分别测定辐照种子中的自由基产额，统计胚根根尖细胞中的染色体畸变频率和咱子的萌发能力，以及种子的萌发能力密切相关。辐照处理时间长，自由基产额高，染色全变率高，萌发生长能力低。四种作物种子的重复实验证明，电子脉冲的辐射效应明显强于Ａｒ＾＋离子脉冲。     

MeV离子辐照拟南芥的萌发规律研究

利用不同能量的F离子和H离子分别辐照拟南芥干种子,通过种子发芽率实验研究了低能离子生物效应与离子种类、离子能量和辐照注量之间的关系。实验结果表明,H离子的辐照效率高于F离子;F离子辐照的种子发芽率曲线,随F离子注量的增加,均呈现先下降后升高再下降的马鞍曲线形状,达到马鞍峰值需要的注量随离子能量的增加而减少。文中对上述现象的可能机理进行了讨论。     

不同电荷态的7Li离子对质粒DNA链断裂的影响

电离辐射致DNA损伤的程度受到很多因素的影响，如剂量、剂量率、射线种类、DNA浓度等。北京师范大学周宏余课题组利用电子顺磁共振谱仪测量了不同电荷态的低能C离子辐照丙氨酸薄膜后产生的自由基浓度，实验结果发现，当离子注量达到10^13cm-2时，随着离子电荷态的增加，产生自由基相对浓度减少。     

受阻胺光稳定剂在60Coγ射线辐照下直接生成氮氧自由基的研究

利用电子自旋共振分析（Electron spin resonance,ESR）研究了几种小分子型和高分子型受阻胺光稳定剂（Hindered amine light stabilizer,HALS）在^60Coγ射线辐照下生成氮氧自由基的规律。在空气中辐照时,几种受阻胺光稳定剂均能产生氮氧自由基。对大多数HALS,在0-10kGy的剂量范围内,氮氧自由基浓度随剂量几乎呈线性快速增加,在剂量大于10kGy以后,氮氧自由基浓度基本保持不变或随剂量呈缓慢增加的趋势。小分子型受阻胺产生的氮氧自由基浓度一般比高分子型受阻胺产生的氮氧自由基浓度高。四甲基受阻胺比五甲基光稳定剂更容易生成氮氧自由基。在氧气中产生的氮氧自由基的浓度为在空气中产生的氮氧自由基的浓度的2倍左右。还讨论了HALS在γ射线辐照下生成氮氧自由基的机理。     

高能Ar离子辐照PET膜引起的表面改性研究

采用傅立叶转换的红外光吸收技术在反射方式下分析研究了35MeV/u Ar离子辐照半晶质PET膜引起的表面改性及其对吸收剂量的依赖性。结果表明，辐照导致PET膜中与晶态区域相关的吸收带强度随吸收剂量增加普遍减弱，而与非晶区域相关的吸收带强度随吸收剂量增加逐渐增加，表明辐照使PET膜发生了非晶化转变。化学键断裂主要发生在苯环的对位和酯的C－O键上，而苯环的基本结构在整个辐照过程中变化较小。非晶化效应和化学键断裂同时依赖于离子的照射剂量和样品表面的电子能量沉积。此外，在约5．0MGy以上的吸收剂量，辐照还引起了炔端基团的形成，炔端基团浓度随吸收剂量的增加显著增加。对实验结果进行了定性解释。     

离子束辐照脱氧核糖核酸(DNA)及其碱基的ESR研究

用电子自旋共振波谱法对氮离子束辐照脱氧核糖核酸和碱基产生的自由基进行了研究。结果表明,离子束辐照DNA和碱基产生的自由基为离子自由基;自由基产额随辐照剂量的增加而上升,最终趋于饱和。在室温(10-20℃)和干燥条件下,对产生的自由基进行了一个多月的观测,不见有大幅度衰减,表明在室温条件下辐照产生的自由基具有较长的寿命。     

聚乙烯辐射接枝甲基丙烯酸β-羟乙酯及其共聚物电容量的研究

用共辐射接枝方法研究了甲基丙烯酸β-羟乙酯(HEMA)在低密度聚乙烯基材上的接枝聚合,结果表明,聚乙烯的接枝率随辐照剂量的增加而增加,随辐照剂量率的增加而下降,随阻聚剂Cu~(2+)浓度的增加而出现峰值。在本实验范围内,HEMA单体浓度对聚乙烯幅照接枝的影响不明显。接枝共聚物的电容量随接枝率的增加而增加。     

木材^60Coγ射线引发自由基的衰变系数

木材经￣（６０）Ｃｏγ射线辐照后，高聚物分子的共价键断裂而产生自由基。福建２１个树种木屑试样经辐照后，用ＥＳＲ测试，主谱ｇ＿０＝２．０１９３的自由基均随剂量Ｄ按指数率变化，最后趋于饱和。α＿ａ与树种有关，但均远小于１。增加木材表面自由基，可以显著提高木材的胶合强度。木材经γ射线辐照后引发的自由基强度大，衰变系数小，稳定性好，具有应用前景。     

Biological effects of implantation and penetration of nitrogen ion beams on wheat seeds

The biological effects of wheat seeds irradiated by 48MeV/u and 20MeV/u ^14N^7 beams are studied,respectively.The results show.both penetration and implantation of heavy ions can significantly inhibit growing pwer(height of plant stem)of wheat seeds.The greater dose is ,the weaker growing power is,and the implantation influence on growing power is stronger than the penetration;a great variety of chromosomal aberrations were observed in root tip cells of irradiated seeds and the aberration frequencies were several hundred times higher than that of the corresponding control;it has been proved by 3H-TdR incorporation test that unscheduled DNA synthesis exists in irradiated wheat seed embryos.It is found by ESR spectroscopy that the variation of free radical concentration with total dose has different features for the pentrated and implanted seeds.     

2,2,6,6-四甲基哌啶-1-氧自由基对低温等离子辐射聚氨酯膜表面过氧自由基的研究

采用2,2,6,6-四甲基哌啶-1-氧自由基(2,2,6,6-Tetramethyl-1-piperidinyloxyl radical,TEMPO)法,测定了经氧气低温等离子体处理后聚氨酯膜表面过氧自由基的浓度,探讨了等离子轰击时间、等离子放电功率、在空气中放置时间等因素对等离子体处理后自由基浓度的影响.在经测定获得的自由基浓度较高的条件下,引发聚氨酯与丙烯酸的接枝聚合,验证了TEMPO法的可行性,讨论了聚合时间对接枝率的影响.丙烯酸在聚氨酯膜表面的接枝共聚由扫描电子显微镜得到确认.在等离子放电功率为600W,放电时间为180s时所测定的自由基浓度最高,相应的接枝率较高.实验结果表明,TEMPO法是一种有效的测定自由基浓度的方法.     

Properties of radicals created by γ-ray irradiation of silk fabrics

The properties of radicals from γ-ray irradiated silk fabrics were studied by electron spin resonance method (ESR). The ESR spectra of silk fabrics irradiated in N2 showed a doublet at room temperature. The doublet became a singlet at g=2.0057 after placing the sample in air for 24 hours. This can be explained by formation of peroxide radicals. The radical concentration of the irradiated silk fabric and the decay rate of radicals are significantly affected by irradiation conditions, which include the absorbed dose, atmosphere, and water content of the silk fabric samples. However, no dose rate effect on the radical concentration was observed. The results are of help in our practice of property modification of silk products by radiation graft copolymerization.     

Penetration depth and concentrationdistribution for implanted heavy ions with low energies in plant seeds bySEM and EDS

The penetration depth and concentration distribution of implanted ions have been studied for low energy heavy ions implanted in the dry seeds of plant,such as peanut,mung bean,sunflower,wheat and radish seeds,etc.by SEM EDS.The results show that the maximum penetration depth is about 12μm for V^ with an energy 200keV implanted in cotyledon of the peanut,18μm,15μm,20μm for V^2 with 90keV implanted in sunflower,wheat,radish seeds,respectively.The penetration depth of implanted Cu^2 with 80keV is about 90μm in the remainder funicle derivative of the mung bean seeds.The experimental result of the maximum penetration depth of implanted V^ in the peanut seeds was compared with the calculated value of the TRIM95.     

Molecular dynamics simulations of CH3 sticking on carbon surfaces, angular and energy dependence

Sticking cross-sections for CH₃ radicals at different angles of incidence and different energies were calculated using molecular dynamics simulations, employing both quantum-mechanical and empirical force models. The chemisorption of a CH₃ radical at 2100 K onto a dangling bond is found to be highly dependent on the angle of incidence of the incoming radical. The sticking cross-section decreases from (10.4 ± 1.2) to (1.4 ± 0.3) Ų when the angle of incidence of the methyl radical increases from 0° to 67.5°. A simple geometrical model is presented to explain the angular dependence. In the sticking process of CH₃ radicals with higher kinetic energies (1, 5, and 10 eV) both a fully hydrogen-terminated surface and a surface with dangling bond were studied. The sticking probability is enhanced as the radical energy increases. We observed sticking onto the fully hydrogen-terminated surface for all cases except for the case when the methyl radicals had energies corresponding to a temperature of 2100 K.     

氯化胆碱在对小麦的辐射保护作用中无效

前一工作报道存在于十字花科植物中的芥子碱对小麦和元麦有辐射保护作用。芥子碱的水解产物为芥子酸和胆碱。为了探索芥子碱辐射保护作用的有效成分,本文用氯化胆碱预处理小麦萌发种子后用X射线辐照。6天后的生长表明氯化胆碱对小麦萌发种子没有辐射保护作用。