辐照对稻米主要品质的影响

研究了60Co-γ射线辐照稻米(糯米、粳米、籼米)对其蛋白质、直链淀粉、总淀粉、淀粉粘度谱、胶稠度的影响.结果表明,经0.5-7 kGy剂量辐照处理的稻米,淀粉含量、胶稠度随辐照剂量的增加而显著降低,淀粉粘度谱的最高粘度、热浆粘度、冷胶粘度也随辐照剂量的增加明显下降.实验得出稻米辐照杀虫剂量应控制在3 kGy以下为宜.     

辐照接枝氟塑料的正电子寿命谱研究

用正电子湮没寿命谱研究了对聚四氟乙烯和聚合氟乙丙烯进入γ辐照接枝的反应机理。结果表明：γ辐照和辐照接枝使聚合物的凝聚态结构发生了变化。随着辐剂量的增加,接枝率不断提高,而正电子湮没长寿命产生明显改变。说明了辐照接枝主要发生在非晶区以及非晶区和晶区的交界处,将实验结果与红外光谱进行了比较。     

辐照药用淀粉的毒性研究

为确保人们食用的安全,对用~(60)Co-γ射线辐照5kGy的药用淀粉的毒性进行研究。通过90只Wistar大鼠的90天喂养试验及短期致突试验观察,证明辐照淀粉对大白鼠的生长、发育、食物利用率、血象、肝功能均无明显影响,亦未见骨髓嗜多染红细胞微核率、染色体畸变率及多倍体增加,证明无遗传毒性反应。Ames试验也说明辐照淀粉不诱发DNA中碱基对的置换型和移码型突变。病理改变及脏器系数的变化与对照组无显著性差异,未显示出对脏器的毒性作用。经上述实验证明食用辐照淀粉是安全的。     

有线控制飞行器的超宽谱辐照效应研究

为研究飞行器在复杂电磁环境下的飞行效能,进行了某型有线控制飞行器及其控制导线在超宽谱辐照下的效应研究.研究表明,飞行作业时,机体及控制导线在超宽谱的辐照下,飞行器将出现控制指令紊乱、无控制指令输出等故障现象,其结果使处于飞行状态的机体失去作业性能.在实验基础上,研究了机体的飞行姿态与干扰强度的关系,确定了飞行器的电磁敏感部位、干扰阈值以及飞行时的敏感阶段,并分析了各种故障效应产生的机理.     

60Coγ射线预辐照制备淀粉-丙烯酰胺接枝物

采用预辐照的方法研究了淀粉与丙烯酰胺的接枝反应,制备出了淀粉与丙烯酰胺的接枝物;采用元素分析法测量了接枝率.对预辐照接枝反应的一些影响因素,如吸收剂量、反应温度、反应时间、阻聚剂及辐照后效应也进行了研究,并获得了相关结果.淀粉预辐照的吸收剂量约10kGy,辐照后10min内在2530C下进行接枝可以获得80%以上的接枝率.     

Study on rapid detection of irradiated rice based on RVA profile

In order to confirm whether the rice sample was exposed to gamma radiation,the changes in starch pasting viscosity of rice irradiated by different absorbed doses with additive acid solution and distilled water were investigated.The peak viscosity of irradiated rice sample was significantly decreased with the increment of absorbed doses even for the samples stored over 360 days.Irradiation samples can be distinguished from non-irradiated samples by their RVA profile as in the acid solution（pH=2.5）,the starch pasting viscosities of irradiated rice samples were apparently higher while the starch pasting viscosities of non-irradiated rice samples were lower than that in distilled water（pH=7.0）.The irradiation absorbed dose can be estimated accurately by the regression equation constructed with peak viscosity and absorbed doses.     

高能氩离子辐照SiO2玻璃的正电子寿命谱学研究

用1．15GeV的氩离子在室温下对二氧化硅玻璃样品进行了辐照,并通过正电子寿命测量技术研究了辐照后材料微观结构的变化。结果表明,在未辐照二氧化硅玻璃中有近81％的正电子是以正电子不的形式湮灭的;根据o-Ps的撞击湮灭寿命确定出未辐照样品的自由体积分布在0．02－0．13nm^3的区域里,平均自由体积半径为2．5nm。辐照后材料的自由体积分布函数变窄,峰位下降,显示样品经辐照后有密度增大的现象。随着剂量的增大,第二正电子寿命成分的强度逐渐增加,而相应于o-Ps的寿命成分的强度逐渐减小,这被认为是由于辐照产生的电离电子在自由体积中漫游,使正电子与这些漫游电子发生湮灭的几率增大,从而减小了正电子素的形成几率。     

HFETR材料辐照精细中子注量率谱研究

采用蒙特卡洛程序(MCNP)模拟计算高通量工程试验堆(HFETR)典型辐照孔道内样品精细中子注量率谱,包括轴向、径向中子注量率谱及172群中子能谱,分析其特点和变化规律,同时比较辐照孔道填充不同材料时的中子能谱。结果表明:不同孔道辐照相同材料及同一孔道辐照不同材料时,所得的能谱分布趋势和特点比较一致。在高能区,中子能谱近似为于裂变中子谱分布;在慢化能区,近似为费米谱分布;而在热能区,近似为麦克斯韦谱分布。     

电子自旋共振波谱技术检测香辛料类辐照食品的研究

本文研究了四种香辛料类食品（花椒、芥末粉、咖喱粉、姜粉）经0—15kGy剂量辐照后电子自旋共振（ESR）波谱特征及信号强度的变化,并探讨了ESR信号强度在220d贮藏期内的变化规律。结果表明,4种香辛料样品辐照前后ESR波谱均有明显区别,ESR波谱信号强度与剂量呈现正相关。在贮藏期内所有样品信号强度均有减弱,除芥末粉外其余样品经过220d后仍能应用ESR法检测判定是否经过辐照处理。这为制定我国辐照食品的ESR检测办法标准提供了依据。     

Depth dependent damage profile in stainless steel irradiated with He-ions

Type 316 stainless steel was irradiated with 24 MeV He-ions up to 3.2 × 10²⁰ ions/m² at ambient temperature. A peak in microhardness occurred at a distance of 105 μm from the irradiated surface. Small dislocation loops were seen at depths ranging from 105 to 114 μm with the peak in number density at 110 μm. A pair of parallel lines with a space of 8 μm centered at a distance of 107 μm from the irradiated surface were revealed on the top surface of the specimen by chemical etching after post-irradiation annealing for l h at 1023 K. The parallel lines correspond to arrays of fairly large Frank loops aligned in narrow bands on each side of a region containing helium bubbles. The observed damage profiles agree with those predicted by Littmark and Ziegler.     

小牛胸腺DNA的MeV重离子辐照研究

重离子辐照DNA分子的研究都集中在SSB和DSB方面,研究辐照产生的除SSB和DSB以外的产物对研究相关的机理很重要,特别是检测组成DNA的基本单元,如碱基,核苷等的生成量和生成规律。本实验用琼脂糖凝胶电泳验证了小牛胸腺DNA辐照产物分片断主要集中在831bp附近,用MALDI-TOF检测证明在1000-30000质荷比范围内没有可检测到的生成物,HPLC分析表明有生物小分子生成,在小分子到链断裂碎片间没有或很少其它产物,说明MeV离子轰击DNA分子造成的损伤并非随机的。     

BaF_2晶体辐射损伤的光谱研究

本文给出了BaF_2晶体被辐照前后的自发光谱、透射光谱和光激发光谱的变化。结果表明,经~(137)Cs和~(60)Co的γ射线辐照后的BaF_2晶体有较强的自发光,在310nm和650nm附近有两个峰。不同晶体的自发光谱不完全相同,同一块晶体的光谱形状不随受照剂量的大小而改变,但光的强度却与受照剂量有关;自发光随时间的衰减具有多种成分。辐照后BaF_2晶体的透射率下降,恢复缓慢,但紫外光照射可以加速透射率的恢复。290nm的光能激发出BaF_2的慢成分光,不同晶体的光激发发射光谱不完全相同,但辐照后无明显变化。     

电离型截面探测器研究

针对强流质子加速器非拦截式的截面测量需求,开展了以剩余气体分子为基础的电离型截面探测器的研究工作。探索了电离信号强度的计算方法,利用CST(Computer Simulation Technology)电磁工作室对电场进行了优化设计,设计加工了一套应用于质子直线加速器的电离型截面探测器,该装置利用高压电极产生的电场引导电离产物,用微通道板放大电离信号,荧光屏和相机组成探测系统。该电离型截面探测器被安装于加速器驱动次临界系统(China Accelerator Driven Subcritical system,ADS)先导专项的注入器I上,在线束流实验证明,该套设备工作稳定正常,实现了束流截面的非拦截式测量。     

DSC studies of retrogradation and amylose-lipid complex transition taking place in gamma irradiated wheat starch

The effect of gamma irradiation (⁶⁰Co) with doses of 5-30 kGy on the amylose-lipid complex transition and retrogradation occurring in gels containing ca. 50% and ca. 20% wheat starch was studied by differential scanning calorimetry (DSC) during heating-cooling-heating cycles (up to three cycles). Transition of the amylose-lipid complex occurs in all the irradiated samples at a lower temperature as compared to the non-irradiated starch. That effect was larger when the radiation dose was higher. A further thermal treatment causes a decrease of the transition temperature in the irradiated samples, with no effect or increase of that temperature observed for the non-irradiated ones. Irradiation hinders retrogradation taking place in 50% gels but facilitates the process occurring in 20% gels. The differences between the irradiated and the non-irradiated samples are more evident in the every next heating or cooling cycle as well as after storage and in the case of ca. 50% suspensions as compared to ca. 20% suspensions. The results point out to the deterioration of the structure of the complexes formed in the irradiated starch as compared to the non-irradiated one.     

电子自旋共振波谱法检测含骨类食品的初步研究

电子自旋共振(Electron spin resonance,ESR)波谱测定是检测含骨类食品自由基的有效方法之一.本工作研究了辐照诱导的含骨类食品的ESR波谱特征、样品制备方法及辐射剂量-效应关系.结果表明,辐照前后ESR波谱图形、g因子和△H皆有明显差异,据此很容易区分辐照与未辐照含骨类食品样品;冷冻干燥和磨碎是样品制备过程中的关键步骤;吸收剂量(0.3-10.1kGy)与ESR信号强度有良好的线性关系;ESR信号的相对强度还与动物种类有关.这为制定我国含骨类辐照食品的ESR检测方法标准提供了依据.