酚酞型聚芳醚酮的辐射效应

一、前言 可溶性含酚酞侧基聚芳醚酮(PEK-C)是我们近年来刚刚开发出的一种新型的具有耐高温、耐水解、耐化学、自润滑性能的工程塑料。它具有如下结构:     

聚二甲基硅氧烷光解离的从头算分子动力学研究

文章采用B3LYP/6-31G(d)方法对含有两个重复结构单元的聚二甲基硅氧烷(PDMS)的周期性边界条件的结构模型进行全构型能量优化,在此基础上,采用从头算分子动力学方法研究其光解离过程.研究结果表明,在化学键解离过程中,PDMS甲基上的H最易且最先脱落,即首先是甲基上的C-H键断裂,生成H自由基和硅甲基自由基,而后,C-Si键断裂,生成甲基自由基和PDMS的主链自由基.计算结果与硅橡胶泡沫的气体辐解产物分析结果基本一致.     

聚三氟氯乙烯薄膜的辐照效应

测量了聚三氟氯乙烯薄膜受Ｘ射线辐照后电荷贮存能力发生的变化，推导了辐照样品表面电位变化的公式，此外，还发现大剂量辐照会引起薄膜样品熔点的降低。     

聚合物的强化辐射交联Ⅱ——聚二甲基硅氧烷的强化辐射交联

应用前文提出的理论,处理了聚二甲基硅氧烷与乙二醇二甲基丙烯酸酯(EGDMA)体系的凝胶数据。定量的计算结果表明,EGDMA对聚二甲基硅氧烷的辐射交联起到了强化作用,而且这种强化作用在低剂量下尤为显著。理论处理实验数据后还指出,在侧基上含有少量乙烯基,可明显地提高聚二甲基硅氧烷的辐射交联产率。     

聚氨酯泡沫塑料的辐射效应研究

用DTG和万能材料试验机等分析测试手段研究了聚氨酯泡沫塑料在辐照前后的热稳定性和力学性能变化 ,并利用GC对辐解气态产物进行了定性定量分析。结果表明 ,聚醚型聚氨酯泡沫塑料在 8.0× 10 5Gy时综合力学性能仍然较好 ,但受辐射降解的作用已有相当的气态产物生成。经辐照以后 ,材料的热性能较为稳定     

辐射化学在辐射生物学发展和研究中的作用

辐射化学是连接辐射物理与辐射生物学的时空桥梁,其理论、模型和实验方法对促进辐射生物学的研究和发展起到不可缺少的重要作用。辐射诱导的化学变化不仅是辐射生物学效应的早期事件,在辐射诱导的DNA损伤与修复、生物辐射敏感修饰剂、辐射诱导的活性氧分子代谢和功能等研究领域都扮演重要角色。随着辐射生物学效应研究朝着系统辐射生物学方向发展,辐射生物学效应发生机理的精确研究和定量描述更需要辐射化学的方法和手段支持。     

稀水溶液中氧化还原酶辐射失活和后失活及保护效应的研究Ⅰ.——稀水溶液中过氧化氢酶辐射失活及保护效应

研究了稀水溶液中过氧化氢酶的辐射失活,给出了过氧化氢酶生物活性与吸收剂量的关系以及辐射气氛、温度和溶液中酶的初始浓度对酶活性的影响。结果表明,低温、较高的酶初始浓度和体系中的氧对过氧比氢酶的辐射失活有不同程度的抑制作用。发现添加剂CH_3CH_2OH、HCOONa和EDTA对稀水溶液中过氧化氢酶的辐射失活有明显的保护作用。同时讨论了失活机理和添加剂保护机理。     

稀水溶液中氧化还原酶辐射失活和后失活及保护效应的研究Ⅱ.——稀水溶液中过氧化氢酶辐射后失活及保护效应

报道了稀水溶液中过氧化氢酶在辐射后的放置期间,其生物活性仍随放置时间不断下降的后失活作用。研究了剂量,初始酶浓度、辐照气氛、温度对过氧化氢酶辐射后失活的影响以及添加剂对酶辐射后失活的抑制作用,发现乙醇、甲酸钠和络合剂EDTA均可有效地抑制酶的辐射后失活。样品在辐照和辐照后放置过程中氧的存在与否是辐射后失活现象的关键,而水辐解的分子产物H_2O_2对诱发这一后失活现象起有重要作用。     

聚甲基丙烯酸甲酯体系研究Ⅲ.聚甲基丙烯酸甲酯辐射裂解

本文研究了聚甲基丙烯酸甲酯的辐射裂解效应。线型结构聚甲基丙烯酸甲酯在室温空气中辐照,1×10~6～1×10~8rad范围内,聚合物分子量随剂量增高而下降的关系呈线性,G_(s)=1.0。交联网状结构聚甲基丙烯酸甲酯在室温空气中辐照后,凝胶溶胶分配变化和M_c随剂量增高而上升的效应,确认发生了裂解变化。     

Amyloid fibril-supported Pd nanoparticles as electrocatalyst for hydrogen peroxide reduction

Palladium nanoparticles(Pd NPs) were fabricated by using insulin amyloid fibrils(INSAFs) as biotemplates.Atomic force microscopy measurements showed that ultrasmall Pd NPs were well adsorbed and dispersed on surfaces of INSAFs. X-ray photoelectron spectroscopy confirmed the partial reduction of Pd ion into metallic Pd(0) probably due to the presence of Cys groups on surface of the insulin fibrils. The electrochemical performance of Pd/INSAFs to reduction of H_2O_2 was further evaluated by cyclic voltammetry. The remarkably high electrocatalytic activity, low detection limitation and excellent stability make the Pd/INSAFs a promising bio-nanoelectrocatalyst.     

Evaluation of the stability of precipitated uranyl peroxide and its storage characteristics in solution

This work studied the stability of uranyl peroxide, which can be obtained as the final product of several processes to treat uranium mixture waste and uranium ore, in solution using various temperature, pH, and ionic strength conditions. The change in concentration of dissolved uranium and hydrogen peroxide from uranyl peroxide, the form of the dissolved uranium species, and the change in morphology of dissolved uranyl peroxide were investigated for 100 or more days. Uranyl peroxide was stable in distilled water at elevated temperatures, but dissolved in other solutions at temperatures higher than 40?°C; a greater amount of uranyl peroxide dissolved in more acidic conditions at elevated temperatures. Uranyl ions that dissolved from uranyl peroxide were able to be recovered as uranyl peroxide in the solution where the dissolution occurs by adding hydrogen peroxide. After the precipitation of uranyl peroxide, the uranyl concentration in the supernatant is low enough for the supernatant to be recycled or released into the environment. The morphologies of the partially dissolved uranyl peroxide and the re-precipitated uranyl peroxide from dissolved uranyl ions were different from that of the initial uranyl peroxide.     

Colorimetric quantification of aqueous hydrogen peroxide in the DC plasma-liquid system

The quantification of hydrogen peroxide(H_2O_2) generated in the plasma-liquid interactions is of great importance, since the H_2O_2 species is vital for the applications of the plasma-liquid system.Herein, we report on in situ quantification of the aqueous H_2O_2(H_2O_2 aq) using a colorimetric method for the DC plasma-liquid systems with liquid as either a cathode or an anode. The results show that the H_2O_2 aqyield is 8–12 times larger when the liquid acts as a cathode than when the liquid acts as an anode. The conversion rate of the gaseous OH radicals to H_2O_2 aqis 4–6 times greater in the former case. However, the concentrations of dissolved OH radicals for both liquid as cathode and anode are of the same order of tens of n M.     

γ-radiation effects on metal oxide particles and their wetted surfaces

ABSTRACT

Typical metal oxide corrosion products of structural materials have been irradiated with γ-rays in ultra-pure water to investigate the effect of radiation on the surface oxide and the nature of adsorbed water. Analysis techniques including thermal gravimetric analysis, differential thermal analysis, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy before and after γ-irradiation were employed to investigate surface structural effects and adsorbed water behaviour. The production of H₂ in the oxide nanoparticle mixtures was investigated by gas chromatography to probe the mechanism of radiolysis in the water/oxide mixtures and the relationship with surface water. The nature of water at the surface of the oxides was affected by γ-radiation and the relationship was dependent on the particle composition. The rate of H₂ production was shown to be oxide dependent, and higher rates of H₂ formation were attributed to the decomposition of surface adsorbed water. Changes to the surface chemistry and H₂ production rates were found to be highly dependent on the surface chemistry of the metal oxide nanoparticle and no bulk structural changes were observed.     

微波辐射H_2O_2漂白麦草浆的研究

进行了麦草浆的水浴加热漂白和微波辐射漂白对比实验,考察了微波辐射H2O2漂白过程中微波辐射功率、处理时间、H2O2及NaOH用量对漂白纸浆性能的影响,采用正交试验的方法对实验条件进行了优化,并用纤维分析法对纸浆纤维形态进行了研究。微波辐射H2O2漂白纸浆的最佳工艺条件是:微波辐射功率240 W、辐射时间2.5 min、H2O2用量5%、NaOH用量4.5%,在此条件下纸浆白度可达59%ISO左右。纤维分析测定结果发现微波辐射漂白前后纸浆纤维形态基本没有发生变化。结果表明,微波辐射替代水浴加热应用于H2O2纸浆漂白是一种切实可行的方法。     

电子束辐照处理水溶液中的活性染料

印染废水是我国工业废水的主要品种之一,如何有效处理印染废水是当今一个重要的研究课题。本文选择两种活性染料为处理对象,研究其在电子束辐照下的降解和脱色。通过染料水溶液受到辐照前后的紫外可见光谱的分析,以及化学需氧量、吸光度和溶液pH值的变化,研究其辐射降解脱色特性。同时研究了过氧化氢对染料辐射降解的协同作用。结果显示利用辐射技术处理印染废水具有相当好的应用前景。     

Transient radiation effects in CMOS inverters fabricated on SIMOX and BESOI wafers

ＴｒａｎｓｉｅｎｔｒａｄｉａｔｉｏｎｅｆｆｅｃｔｓｉｎＣＭＯＳｉｎｖｅｒｔｅｒｓｆａｂｒｉｃａｔｅｄｏｎＳＩＭＯＸａｎｄＢＥＳＯＩｗａｆｅｒｓＺｈｕＳｈｉ－Ｙａｎｇ（竺士炀），ＬｉｎＣｈｅｎｇ－Ｌｕ（林成鲁）（ＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆ...     

同步辐射软X射线对单细胞的辐射损伤

应用国家同步辐射实验室软X射线显微术光束线的光学系统,搭建了适合软X射线单细胞辐照损伤效应研究的实验装置,选择氧元素K吸收边能量对Hela细胞进行单细胞辐照,运用单细胞凝胶电泳技术进行辐照损伤评价.实验结果表明,辐射损伤效应与辐射剂量有依赖性关系.     

Corrosion behavior of TiO2-treated type 304 stainless steels in high temperature water containing with hydrogen peroxide

ABSTRACT

Titanium dioxide (TiO₂) treatment coupled with ultraviolet irradiation was selected as a corrosion mitigation technique for Type 304 stainless steel (SS) in high-temperature pure water with the presence of hydrogen peroxide (H₂O₂). Type 304 SS specimens were pre-oxidized in oxygenated pure water at 288 °C and then coated with TiO₂ nanoparticles by hydrothermal deposition. Electrochemical polarization analyses were conducted to investigate the corrosion behavior of both TiO₂-treated and pre-oxidized specimens in 288 °C pure water with 300 ppb H₂O₂. Ultraviolet (UV) irradiation was then imposed upon the TiO₂-treated specimens to examine if there was any distinct photoelectric effect on the corrosion behavior of the treated samples. It was found that the electrochemical corrosion potentials of the TiO₂ treated specimens under UV irradiation were 10–20 mV lower than those without UV. In addition, the corrosion current densities of the treated specimens were also lower in the presence of UV radiation. Without UV radiation, however, no significant differences were observed between the TiO₂ treated and untreated specimens. These results indicate that the TiO₂ treatment in combination with UV radiation would reduce the corrosion rate of Type 304 SS in H₂O₂-rich, high-temperature pure water.     

基于半导体集成电路辐射效应的空间辐射环境探测器

空间辐射环境能够引起半导体集成电路发生的总剂量效应、单粒子效应等辐射效应,可以被用来进行空间辐射环境监测。在一定条件下,基于此原理的探测器具有常规的面垒型探测器以及PIN型探测器等所不具备的优点。尤其适合航天器舱内带电离子探测和用于航天医学的个人辐射剂量探测。介绍了三种基于半导体器件辐射效应的探测器。