核电站辐照监督管焊接技术及焊接质量控制

介绍了某反应堆压力容器焊缝及热影响区辐照样品管制造要求,通过分析其焊接工艺,结合制造厂经验反馈,研究了辐照监督管焊接中常见的质量问题,提出从优化焊接参数、提高焊接设备稳定性和做好焊接母材表面检验三个方面进行控制,防止辐照监督管焊接产生缺陷,从而提高焊接质量,为后续的辐照监督管焊接质量控制提供指导。     

臭氧、电子束辐照降解玉米赤霉烯酮和赭曲霉毒素A

玉米赤霉烯酮(Zearalenone,ZEN)和赭曲霉毒素A(Ochratoxin A,OTA)毒性较大、污染范围较广,一直是中国食品行业重点关注的问题。采用毒素标准品,分别考察臭氧和电子束辐照对其降解效果。研究结果表明,2 mL50μg/mL的ZEN经2.0mg/L的臭氧处理10s后,ZEN未检出;经12kGy的电子束辐照后,降解率达86%,且0.5~5.0μg/mL时,ZEN浓度对其降解效果无显著影响(P0.05),ZEN在乙腈中较甲醇降解更快。2 mL 5μg/mL的OTA经50mg/L的臭氧处理30s后,OTA降解率为22%,当处理时间延长至180s,降解率仍无显著提高;0.1~1.0μg/mL浓度的OTA经12kGy剂量电子束辐照后,降解率均在90%以上,且OTA浓度对其降解率无显著影响(P0.05),OTA在乙腈中较甲醇更快降解。臭氧较电子束易降解ZEN,电子束较臭氧更易降解OTA。研究结果为臭氧和电子束辐照降解不同真菌毒素提供了理论参考和实践依据。     

Changes in wheat and potato starches induced by gamma irradiation: A comparative macro and microscopic study

Wheat and potato starches were treated by gamma irradiation (0, 3, 5, 10, 20, 35, and 50 kGy). Apparent amylose content, gelatinization maximum consistency, swelling power, viscosity, and textural parameters decreased in potato and wheat starch pastes as irradiation dose increased. Nevertheless, the decrease of apparent amylose content and swelling power was greater in potato starch than in wheat one. High gamma irradiation doses made potato starch granules more sensitive to shear. On the other hand, no modification in the granule shape was observed by scanning electron microscopy. However, through heat-treatment, starch granules destroyed as irradiation dose increased. Consequently, the effect of irradiation on granular structure appeared to be greater in potato starch than in wheat starch.     

Ames Test to Detect Mutagenicity of 2‐Alkylcyclobutanones: A Review

Food irradiation is an effective and safe method for preservation and long‐term storage, and it is approved for use in over 60 countries for various applications in a wide variety of food products. This process is performed by use of accelerated electron beams, X‐rays, or gamma radiation (⁶⁰Co or ¹³⁷Cs). 2‐Alkylcyclobutanones (2‐ACBs) are the only known radiolytic products generated from foods that have fatty acids (triglycerides) and are subjected to irradiation. Since the 1990s toxicological safety studies of 2‐ACBs have been conducted extensively through synthetic compounds, then and tests to determine if the compounds have any mutagenic activity are strictly necessary. The Ames test was chosen by many researchers to assess the mutagenicity of 2‐ACBs. The test uses distinct bacterial cell lines Salmonella typhimurium to detect point mutations at sites guanine–cytosine (G–C) and Escherichia coli to detect point mutations at sites adenine–thymine (A–T). This bibliographic research aims to bring together all the results obtained and a comparison and cell lines used, type of plates, and solvents. This research showed that no mutagenic activity was observed in any of the cell lines and concentrations evaluated by the works of authors, so the 2‐ACBs compounds showed no mutagenic substance in concentrations detectable by the Ames test.     

辐照对透明质酸理化特性的影响

采用⁶⁰Co-γ射线对0.5g/100mL 透明质酸氯化钠溶液进行辐照处理,通过溶液的pH 值、黏度值、色度和红外光谱及紫外光谱等变化研究辐照对透明质酸理化特性的影响。结果表明：辐照降低透明质酸的分子质量、pH值、特性黏度,溶液的颜色比未辐照的更黄。通过紫外和红外扫描观察,透明质酸在辐照前后的吸收特征峰没有太大的变化,吸收强度发生变化。辐照后透明质酸对DPPH 自由基的清除作用随着辐照剂量的增大逐渐增强。     

γ辐照装置辐射安全监督管理的一些思考

结合γ辐照装置辐射安全例行监督检查活动中的一些新关注点,对γ辐照装置辐射安全监管中发现的一些问题进行探讨,提出γ辐照装置安全运行管理的建议,为加强装置安全运行管理提供相关参考。        

Denitrification from diesel by triethylammonium hydrogensulfate ionic liquid under microwave irradiation

The basic nitrogen compounds (BNC) in diesel were removed using triethylammonium hydrogensulfate ionic liquid as the complexing agent under microwave irradiation, and alcohol was used as the extractant. The effect of factors on removing BNC from diesel was reviewed systematically. The result showed that the optimum denitrification process was as follows: microwave power was 300 W, microwave irradiation time was 6 min, volume ratio of ionic liquid to diesel was 10:1, the volume ratio of hydrogen peroxide to ionic liquid was 3:1, and the volume of extractant was 15 mL. The BNC in diesel was reduced from 85.79 μg/g to 3.26 μg/g and the denitrification rate reached 96.2%.     

层状壳聚糖水凝胶的制备与性能

通过两步低温辐射和冷冻/解冻循环相结合的方法制备聚乙烯醇/聚氧乙烯(PVA/PEO)为基层,聚乙烯醇/壳聚糖(PVA/CS)为上层抗菌功能层的层状壳聚糖水凝胶。通过对吸收剂量、电子束流、聚合物溶液浓度等的研究确定最佳制备工艺,并通过溶胀性能、力学性能、抗菌性能及红外光谱和扫描电镜表征所得层状水凝胶的结构与性能。结果表明,该方法制备的层状壳聚糖水凝胶具有明显的层状结构,层间结合紧密,壳聚糖结构未改变;层状水凝胶的溶胀性能随着壳聚糖含量增大而逐渐增大,60%CS含量平衡溶胀度达到2 200%;层状水凝胶力学强度随着壳聚糖含量增加而先增大后减小,40%CS含量下层状水凝胶从PVA/PEO凝胶的0.35MPa提高到0.47 MPa;抗菌性能测试表明层状水凝胶对大肠杆菌和金黄色葡萄球菌均具有明显的抑菌效果,抑菌性能随着壳聚糖含量的提高而增大。