尾矿库中U、Th和226Ra在亚粘土层的垂向迁移

在某铀尾矿库运行了31年后,取库底下方的亚粘土样,测量了从库底迁移的U、Th和226Ra的比活度分布.为研究其迁移规律,还测量了尾矿的颗粒分布、不同颗粒尾矿中核素的比活度和浸出因子、核素在亚粘土层的分配系数等参数,并采用一维对流弥散模式拟合得到核素在亚粘土层中比活度分布曲线.结果表明,矿泥是尾矿中的主要成分,其中的核素比活度高于矿砂;而浸出因子则低于矿砂.库底下方天然的和建库时人工铺垫的亚粘土层对三种核素具有较强的吸附滞留能力,从而有效地减少了核素的垂向迁移;U、Th和226Ra在亚粘土中的分配系数分别为62、1.3×103和9.8×102 mL/g,在库底下方核素比活度降到本底水平的距离,U为1.2 m,Th和226Ra为0.2 m.     

大黄素对实验性自身免疫性甲状腺炎小鼠辅助型T细胞亚群的影响

目的: 研究大黄素对实验性自身免疫性甲状腺炎（experimental autoimmune thyroiditis,EAT）小鼠甲状腺的保护作用和机制。方法: 通过过量碘剂诱导非肥胖型糖尿病（non-obese diabetic,NOD）小鼠建立EAT动物模型,造模4周后各实验组摄入不同剂量的大黄素。造模8 周后检测小鼠血浆甲状腺球蛋白（TgAb）及甲状腺炎症程度以观察大黄素对EAT小鼠的保护作用。流式细胞术检测小鼠外周血、脾脏T细胞亚群,分析大黄素对EAT小鼠外周血、脾脏 Th1、Th2 细胞流式检测频率的影响。ELISA法检测血浆IL-4、IFN-γ水平。结果:（1）甲状腺病理学观察,各大黄素实验组较模型组甲状腺淋巴细胞浸润程度减轻,分级比较差异有统计学意义（P<0.01）;（2）造模后的各组小鼠血浆TgAb水平明显升高,各实验组升高幅度低于模型组,组间有统计学差异（P<0.01）;（3）造模后的各组小鼠血浆IL-4、IFN-γ、外周血单核细胞以及脾脏淋巴细胞中CD+3 CD+ 4IL-4+ 、CD+ 3CD+4IFN-γ+ 、CD+3CD+8IL-4+和CD+ 3CD+8IFN-γ+T细胞频率均较对照组明显增高（P<0.01）,但各实验组升高幅度低于模型组小鼠。结论: 过量碘剂诱导NOD小鼠自身免疫性甲状腺炎造模是可行的;大黄素对造模小鼠甲状腺炎自身免疫反应有一定抑制作用。大黄素通过抑制CD+4CD+8T淋巴细胞分泌IL-4和IFN-γ,从而抑制造模小鼠的自身免疫反应。     

中子活化法测定~(232)Th裂变产物产额

采用中子活化法测量了~(232)Th的裂变产物及其累积产额。利用加速器T(d,n)~4He反应产生的14.9 MeV高注量中子长时间照射ThO_2样品,用高纯锗γ谱仪测量其特征γ谱,求得较长半衰期核素~(99)Mo、~(141)Ce、~(143)Ce、~(131)I、~(140)Ba等的裂变产额,实验结果的典型误差为4%。其中,利用MCNP程序对中子的多次散射效应和自屏蔽效应进行修正,同时考虑了中子注量波动及γ射线在样品中的自吸收影响。     

制备方法对氧化石墨烯氧化程度及对Th(IV)、U(VI)吸附的影响

采用Hummers方法、优化Hummers方法及改进Hummers方法合成氧化石墨烯, 并通过FT-IR、TGA、XRD、XPS、SEM以及元素分析等手段对制备产物进行了表征。结果表明, 利用优化Hummers方法制备得到的氧化石墨烯具有较高的氧化程度。三种产物对Th(IV)、U(VI)的等温吸附实验结果表明, 采用优化Hummers方法制备的氧化石墨烯对Th(IV)的最大吸附量为192.3 mg/g, 相比于Hummers方法制备产物的吸附能力提高了38.5%; 对U(VI)的最大吸附量为156.2 mg/g, 吸附能力提高了28.1%, 三种样品对Th(IV)、U(VI)的吸附都更加符合Langmuir等温吸附模型。此外, 考察了优化Hummers方法制备的氧化石墨烯吸附Th(IV)、U(VI)的动力学和热力学参数, 证实氧化石墨烯吸附Th(IV)、U(VI)符合准二级动力学方程, 是自发吸热行为。     

Experimental determination of photofission cross-sections of Th using electron accelerator

Photofission cross-section of ²³²Th was measured using Bremsstrahlung radiation energy 7.4–9.2 MeV with energy step of 0.3 MeV by employing Lexan polycarbonate film as Solid State Nuclear Track Detectors (SSNTD). The photon intensity from the Microtron accelerator facility was estimated to be 10¹⁰ photons/s at a distance of 15 cm from the Bremsstrahlung converter using EGS-4 code (Nelson et al., 1985). Photofission cross-sections were evaluated using fission fragment angular distribution measurements. The present experimental results were compared with EMPIRE-2.19 (Herman et al., 2005) code prediction of RIPL-1 and RIPL-2 ( and ) and a new analytical formula (Gupta and Saxena, 2005) for fission barrier.     

钍(Ⅳ)离子在泥炭上的吸附研究

采用静态批次吸附法研究了泥炭对Th4+的吸附行为。探讨了泥炭粒径、固液质量体积比、振荡时间、溶液pH值、离子强度等因素对吸附的影响,并确定了室温下不同离子强度时的吸附等温线。试验结果表明:溶液pH值对泥炭吸附Th4+影响较大,离子强度的影响较小;吸附过程符合Langlmuir方程;泥炭对Th4+的吸附主要通过表面络合进行。     

The impact of transgenic papaya (TPY10-4) fruit supplementation on immune responses in ovalbumin-sensitised mice

BACKGROUND: A transgenic papaya line (TPY10‐4) that is resistant to both papaya ringspot virus (PRSV) and papaya leaf distortion mosaic virus (PLDMV) has been developed in Taiwan. This study investigated the immunomodulatory properties of transgenic TPY10‐4 and its native (TCK) papaya fruits using an ovalbumin (OVA)‐sensitised mouse model. Both green and ripe papaya fruits at low (0.2 g powder kg^?1 body weight (BW)) and high (1.6 g powder kg^?1 BW) doses were administered to experimental mice by intragastric gavage for 5 weeks. Changes in serum total immunoglobulin A (IgA), IgE, IgG and IgM levels, OVA‐specific IgE, IgG1 and IgG2a titres and Th1/Th2 cytokine secretions using splenocytes were determined. RESULTS: Transgenic TPY10‐4 or native TCK papaya fruit supplementation did not significantly affect body, visceral organ and relative tissue weights, total IgE antibody levels, OVA‐specific IgE and IgG1 antibody titres or OVA‐stimulated interferon‐γ (IFN‐γ), interleukin‐2 (IL‐2), IL‐4, IL‐5 and IL‐10 secretions using splenocytes. However, transgenic papaya fruits markedly increased serum total IgM levels. CONCLUSION: This study suggests that transgenic TPY10‐4 papaya fruits do not increase the allergenic potential of OVA by oral administration but may have a protective immunity via increasing the serum total IgM level. Copyright © 2010 Society of Chemical Industry     

Immunomodulatory Activity of Recombinant Ricin Toxin Binding Subunit B (RTB)

Ricin toxin binding subunit B (RTB) is one of the subunits of the ricin protein. RTB has been used as adjuvant, but little is known about its mechanism. In this study, we found that RTB increased not only nitric oxide (NO) release, but also tumor necrosis factor (TNF)-α and interleukin (IL)-6 production in mouse macrophage cell line RAW264.7 cells. They subsequently exhibited enhanced ConA-induced T-cell and LPS-induced B-cell proliferative responses. We also examined the cytokines that were produced from splenocytes following in vitro RTB administration. Increased levels of IL-2, interferon (IFN)-γ and TNF-α were observed, while IL-4 and IL-5 were unaffected. These results demonstrate that recombinant RTB can act on the immune system and activate T-cells by introducing a Th1 immune response. Th1 cells might be the primary cellular target affected by RTB. Our results suggest that the recombinant RTB can promote the activation of macrophages and has a beneficial effect on immunomodulatory activity.