小剂量8102对大鼠急性铀中毒的促排效果

研究８１０２不同剂量和连续给药对大鼠急性铀中毒的促排效果。大鼠中毒硝酸铀酰（５００μｇ／鼠）后给予不同剂量８１０２（０～１００ｍｇ／ｋｇ），测定尿铀排出量及肾铀蓄积量。结果：大鼠肌肉注射８１０２及灌胃给予８１０２促排轴的最小有效剂量分别为５ｍｇ／ｋｇ和２０ｍｇ／ｋｇ；８１０２连续给药与一次性给药相比未见尿铀排出量的显著增高和肾铀蓄积量的显著降低。８１０２是一个很有希望的铀促排螯合剂，值得进一步深入研究。     

螯合剂BPCBG对急性铀中毒大鼠的促排效果及肾损伤的保护作用

目的 探讨螯合剂BPCBG对急性铀中毒大鼠促排作用的量-效和时,效关系以及对铀致肾损伤的保护作用.方法 Sprague-Dawley( SD)雄性大鼠按随机数字表法分为正常对照组、铀中毒组、不同剂量BPCBG组和DTPA-CaNa3组.给药组大鼠于腹腔注射醋酸铀酰(100μg/只)后,立即分别肌肉注射60、120和600μmol/kg BPCBG及120和600μmol/kg DTPA-CaNa3,或于注射醋酸铀酰前0.5和2h、铀中毒后0、0.5、1及2h肌肉注射120 μmol/kg BPCBG,铀中毒组于注射醋酸铀酰后立即注射等体积生理盐水,正常对照组仅注射生理盐水.采用ICP-MS方法检测24 h尿铀排出量和肾、骨中铀蓄积量.大鼠注射醋酸铀酰(500 μg/只)后立即注射600 μmol/kg BPCBG和1200 μmol/kg DTPA-CaNa3,48 h后检测血清肌酐(SCR)与尿素氮(BUN)含量,取一侧肾脏做肾组织病理切片观察.结果 铀中毒后立即注射不同剂量BPCBG(60、120和600 μmoL/kg)使24h尿铀排出量比铀中毒组增加(t =2.22、4.43、5,80,P＜0.05),肾和骨铀蓄积量下降(t.3.33、5.59、4.53,P＜0.01和t=2.15、8.70、9.10,P＜0.05),随给药剂量增加促排效果明显提高.提前0.5h或延迟0.5和1h给予BPCBG,仍有较好的排铀效果(与铀中毒组比较,尿铀排出量:提前0.5 h t=4.34,延迟0.5 ht=3.35,P＜0.05;肾铀蓄积量:t=5.75、7.74、5.87,P＜005:骨铀蓄积量:t=6.43、5.22、2.60,P＜0.05),但随铀中毒和给药间隔时间的延长而下降.BPCBG立即给药能明显减轻铀中毒致肾脏的病理损伤,使SCR及BUN含量降低至正常对照组水平,对铀致肾功能损伤具有保护作用.DTPA-CaNa3虽然能明显降低大鼠肾铀蓄积量(与铀中毒组相比,120和600-μmol/kg,t =2.28、3.35,P＜0.05),但未能显著增加尿铀排出量,骨铀蓄积量还有增加趋势,并且对铀致大鼠肾损伤无保护作用.结论 BPCBG对急性铀中毒大鼠有良好的促排效果与肾脏保护作用,有可能成为一种新型铀促排螯合剂.     

天然铀纯化与转化废物最小化对策建议

在天然铀纯化与转化环节中,会产生含铀低水平放射性废物.本文在介绍天然铀纯化与转化废物特征及处理基础上,回顾天然铀纯化与转化废物最小化主要策略和良好实践,分析我国天然铀纯化与转化废物最小化现存主要问题,提出相应改进措施,为天然铀纯化与转化废物最小化实施与管理提供参考.     

Studies on separation and purification of fission 99Mo from neutron activated uranium aluminum alloy

A new method has been developed for separation and purification of fission ⁹⁹Mo from neutron activated uranium–aluminum alloy. Alkali dissolution of the irradiated target (100 mg) results in aluminum along with ⁹⁹Mo and a few fission products passing into solution, while most of the fission products, activation products and uranium remain undissolved. Subsequent purification steps involve precipitation of aluminum as Al(OH)₃, iodine as AgI/AgIO₃ and molybdenum as Mo-α-benzoin oxime. Ruthenium is separated by volatilization as RuO₄ and final purification of ⁹⁹Mo was carried out using anion exchange method. The radiochemical yield of fission ⁹⁹Mo was found to be >80% and the purity of the product was in conformity with the international pharmacopoeia standards.     

Analysis of uranium in the insoluble residues after decomposition of soil samples by various techniques

A comparison of different dissolution techniques for determination of uranium in soil samples was made. Conventional wet dissolution with mixtures of HNO₃, HClO₄ and HF acids, microwave dissolution using HNO₃ and HF, and alkaline fusion with Na₂CO₃ and Na₂O₂ were evaluated. For testing the effectiveness of the dissolution procedures, two reference materials and six soil samples from the surroundings of a former uranium mine were investigated. It was observed that the content of uranium in the residues determined by INAA represents a significant contribution to its total concentration in the sample, especially in the case of microwave dissolution.     

MYCORRHIZA INOCULATION IN FORESTRY PRACTICE

Microbiological factors in mycorrhiza inoculation of trees are discussed with emphasis on Australian research results. These include natural occurrence of mycorrhiza fungi, differences in efficiency of mycorrhizas and establishment of inoculum.     

International responses to the threat of nuclear smuggling from Russia*

In both Russia and the United States there is increasing awareness of the security problem left after the Cold War by former Soviet military nuclear establishments, compounded by the severe difficulties of the Russian economy. Attempts are underway to provide American and other assistance for improving security and transparency; halting the production of highly‐enriched uranium and plutonium; and disposing of the large surplus stocks of these weapon materials.     

Determination of uranium in aqueous attenuating samples using gamma-ray spectrometry

In the present work, a method for determination of uranium concentration in aqueous solution in standard geometry from attenuating samples has been developed based on modification of the empirical approach of Venkataraman and Croft [2003. Determination of plutonium mass using gamma-ray spectrometry. Nucl. Instrum. Methods Phys. Res. A 505, 527–530]. The method makes use of the multiple gamma (γ)-rays emitted by ²³⁵U and depends on the empirical relation between apparent mass of the sample and γ-ray energy. It was possible to determine uranium concentration in the range of 12–400 mg/ml rapidly by this method without applying transmission corrections.     

电感耦合等离子体质谱法与液体激光荧光法分析水中铀的比较

目的 建立微波消解、电感耦合等离子体质谱（ICP-MS）测定水中铀的方法,并与液体激光荧光法进行比较。方法 应用建立的微波消解、电感耦合等离子体质谱法（ICP-MS）和液体激光荧光法分别测定不同水样中的铀含量。结果 液体激光荧光法和ICP-MS法的检出限分别为0.021 μg·L^-1和0.003 μg·L^-1,测定结果的标准偏差范围分别为1.20%~4.24%和0.78%~3.46%,精密度分别为3.02%和0.71%,采用两种方法对实际样品进行分析,结果吻合。结论 ICP-MS测量水中铀的检出限低,精密度和准确度更高,但仪器昂贵,测量成本高,因此每个实验室要根据实际条件及样品含铀量大小选择分析方法。     

Neurological effects of acute uranium exposure with and without stress

Circulating uranium rapidly enters the brain and may cause adverse effects on the nervous system that are potentially modulated by stress. In this study, the neurological effects of a single intramuscular injection of 0, 0.1, 0.3, or 1 mg uranium/kg (as uranyl acetate, UA) in rats were examined in the presence and absence of stress. Treatment with UA produced time and dose-dependent increases in serum and regional brain uranium levels. While serum levels returned to control levels by day 30, brain levels remained elevated. Application of stress did not affect the distribution or retention of uranium. Exposure to 1 mg U/kg significantly decreased ambulatory activity, weight gain, forelimb grip strength and transiently impaired working memory. Effects on grip strength and memory were prevented by application of stress prior to uranium exposure. Striatal dopamine content was reduced by 30% 3 days after treatment with 1mg/kg (59+/-6 nmol/mg tissue versus 41+/-5 nmol/mg tissue), but levels returned to control 7 days after uranium exposure. The effect on dopamine was ameliorated by prior application of stress. Exposure to UA did not alter 3,4 dihydroxyphenylacetic acid (DOPAC) levels or numbers of D2 receptors in the striatum. No effect of uranium or stress was observed on levels of GABA, serotonin, norepinephrine, or glutathione (GSH) in the striatum, hippocampus, cerebellum, or cortex. These results indicate that single intramuscular exposures to uranium produce sustained elevation of brain uranium levels and at doses above 0.3 mg/kg can have adverse neurological effects. Application of stress prior to uranium administration modulates neurological effects, but the mechanism is not due to effects on uranium distribution. Uranium exposure also produced renal toxicity which must be considered to accurately assess the effects of uranium on neurological function.