基于EPR检测技术的香兰素热解机理研究

采用香兰素为木质素模型化合物,结合电子顺磁共振技术（EPR）以检测其热解反应的中间产物,通过确定中间产物的变化规律论证香兰素的热解机理及热解的反应路径。结果表明,对于香兰素而言,原位检测得到结焦中间产物的前驱体和一大部分稳定的碳自由基,而冷阱-捕获到的自由基主要为苯甲酰自由基、甲基自由基、OH自由基和H自由基。证明了香兰素的热解反应过程中存在自由基反应,同时也确认并提出了香兰素热解的反应路径。     

乙丙橡胶电力电缆绝缘一步法硅烷交联工艺

介绍了乙丙橡胶硅烷交联机理和一步法硅烷交联新工艺,针对一步法硅烷交联新工艺,简要阐述了原材料的选择、复合硅烷的配方、加工工艺等;同时介绍了一步法硅烷交联乙丙橡胶绝缘电力电缆的性能指标。     

酶在接近无水有机介质中的生物催化特性

介绍了接近无水条件下以悬浮状态存在的酶以及固定化酶生物催化特性。采用电子顺磁共振(EPR)及核磁共振(NMR)研究了水与酶之间的关系。在有机溶剂中加水和不加水情况下,处于悬浮状态的酶及固定化酶结构和功能存在差别。研究发现,尽管以悬浮状态存在的酶和固定化酶结构明显不同,但水含量、酶活性、酶柔性以及活性位点极性之间存在着密切的关系。结果表明,在含水量很少的条件下,水对酶活性位点的生物催化起着关键作用。     

An improved method to identify irradiated rice by EPR spectroscopy and thermoluminescence measurements

Minimal change in irradiated foods with low dose treatment makes the identification process a difficult task. Two independent physical methods, electron paramagnetic resonance (EPR) spectroscopy and thermoluminescence (TL) detection were employed for detection of irradiation treatment on Basmati rice. EPR investigation of 0.5–2.0 kGy irradiated rice samples showed a short lived, asymmetric, dose dependent spectrum (g = 2.005), characterised by the radicals of irradiated starch. However, this signal disappears with time. The present work explores the possibility to identify irradiated rice by the relaxation characteristics and thermal behaviour of the radicals. This study reports for the first time that the different microwave saturation behaviours of the signal (g = 2.004) in irradiated and non-irradiated rice samples provide an important clue to identify radiation treatment beyond the period when the radiation specific EPR spectral lines have disappeared. TL investigation involving scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX) of the poly-minerals isolated from the rice samples allowed to discriminate clearly between irradiated and non-irradiated samples even after a prolonged period of storage.     

固溶处理温度对304奥氏体不锈钢敏化与晶间腐蚀的影响

采用电化学动电位再活化法(EPR)研究了经950℃和1050℃固溶处理304奥氏体不锈钢晶间腐蚀敏化度Ir/Ia、敏化时间t和敏化温度T之间关系,根据腐蚀速率Rmpy与微观腐蚀形貌绘制了304不锈钢敏化的TTS曲线,探讨了固溶处理温度改变对TTS曲线的影响。结果表明,1050℃固溶处理试样的耐晶间腐蚀性能优于950℃固溶处理试样。     

Radiation-induced defects in different silicon (111) wafers by 400 keV electron irradiation

The energy deposition for low-energy electron beam on Si-SiO2 models was calculated by Monte-Carlo method. Making use of electron paramagnetic resonance (EPR) technique, an investigation of the effect of dopant type and concentration on EPR signal variations was carried out by using p-type and n-type silicon(111) wafers with concentration of 1×1015 cm 3 and 1×1017 cm 3, and the changes of intensity of defect paramagnetic centers before and after irradiation of electrons were compared. The chemical states of Si-SiO2 structure were determined by X-ray photoelectrons spectroscopy(XPS). The results clearly indicate that the effects of dopant variations (type and concentration) are of obvious difference. Compared with p-type silicon, n-type silicon, especially with higher dopant concentration, tends to produce defect at the interface under low-energy electron irradiation with certain flux, which arises from the hole trapped on a nonbridging oxygen atom bonded to P. It is represented in the form of distinct changes of POHC intensity and P2P spectrum. According to the theoretical and experimental data, the relationship among electron energy deposition, chemical states of element Si at SiO2 -Si(111) interface, and radiation effect were analyzed and discussed.     

核电厂土建与安装施工主力吊机选型与布置

核电厂土建与安装施工需要使用大型吊机完成各类大件设备的吊装,CPR1000、EPR、AP1000各种堆型现场布置不同,需吊装的大件设备也不尽相同。在项目施工前期,必须根据各种堆型特点选择不同吊装能力的大型吊机,规划合适的站位点和转移通道,方能保证项目土建与安装工作顺利开展。通过对CPR1000、EPR、AP1000各种堆型大件吊装需求进行分析,提出各堆型典型的土建与安装主力吊机选型与布置方案。     

EPR安全壳高能管道贯穿件应力分析

介绍了EPR机组安全壳高能管道贯穿件的结构特点,并对该类型贯穿件的应力分析方法做了重点描述。高能管道贯穿件的应力分析一般分为两个步骤:首先进行热分析,得到结构的温度分布,并判断温度是否满足安全壳混凝土的温度限值要求;第二步进行热-机械耦合分析,得到结构在各种工况下的应力分布,最后根据RCC-M规范的具体要求进行贯穿件应力的评定。分析过程中考虑结构的轴对称特征,采用平面模型进行简化。本文结合具体算例,采用ANSYS程序进行建模计算分析,并采用RCC-M规范进行了高能管道贯穿件的应力评定。     

三代核电EPR 1 750 MW机组常规岛汽机房变阶柱偏压性能试验

以台山核电站一期工程EPR 1 750 MW常规岛大型钢结构厂房柱局部上大下小变阶段为对象,通过3个1∶5模型柱段试件的偏心受压试验,研究试件的破坏特点、应变特点、挠曲变形特点以及承载力特点等力学性能。结果表明：局部大坡度变截面及截面突变的过渡方式对构件的偏压性能不利,构件的屈服承载力降低,挠曲变形增大;截面突变同时加厚突变区域的腹板并增设加劲肋对改善构件偏压性能的作用不明显。研究成果可为今后同类结构构件的设计提供参考。     

基于加权空间离群点度量的随机脉冲噪声降噪算法

针对排序统计类降噪算法在随机脉冲噪声（RVIN）图像降噪过程中,对图像边缘和细节部分噪声识别不够准确以及恢复比较模糊的问题,提出了基于加权空间离群点度量（SLOM）的脉冲噪声降噪算法WSLOM-EPR。该算法以优化的空间距离差为基础,引入图像邻域均值和标准差,建立反映局部边缘细节特征的噪声检测方法,提高边缘细节处噪声的识别精度;然后以精确检测结果为基础,优化保边正则（EPR）函数,提高算法的执行效率,并增强算法保留边缘细节的能力。仿真结果显示,WSLOM-EPR算法在40%到60%噪声密度下对噪声点的误检和漏检综合表现优于对比算法,且能在两者之间保持一个较好的平衡;降噪后的峰值信噪比（PSNR）好于对比算法中的大多数情况,且边缘细节在视觉上更加清晰连续。结果表明WSLOM-EPR算法提高了噪声检测精度,有效地保持了恢复图像的边缘细节信息。