To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The r...To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The radioactivity of the proposed hydrophone is strictly controlled by selecting pure raw materials, especially active piezoelectric ceramics. The electroacoustic performance of the hydrophone is improved by making structural optimization. High sensitivity and aimed directivity are achieved using 33-mode piezoelectric ceramic rings arranged in series and improvement in the radiating head of the Tonpilz hydrophone, respectively. All electroacoustic performances are studied through finite element analyses.The simulations indicate that the electroacoustic performances of the hydrophones in linear alkylbenzene-based liquid scintillator can be approximately predicted according to the results in water because their differences caused by two types of acoustic media, water and liquid scintillator, are known. The tests show that the hydrophone prototype can achieve a maximum sensitivity of-209.3dB and a beamwidth of 132.2° at a frequency of 143 kHz.In addition, eight hydrophones only contributed to a background radioactivity level of 26 ± 4 mHz in the neutrino analysis.展开更多
The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,...The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,zircon,monazite,xenotime,columbite,fergusonite,and unknown rare earth elements(REEs)bearing minerals as well as cassiterite.Special emphasis on REE content of thorite,uranothorite,zircon and xenotime has been done to correlate them with the increase of uranium contents in these sediments.The key evidence for the presence lowtemperature alteration processes includes the presence of some zircon crystals as remnants after complete dissolution of the overgrowth zircon in severe acidic environment,the sulphur content,biogenic minerals,occurrence of unusual minerals as cassiterite pore filling in zircon,variation in the REEs content from the surrounding granites to the stream sediments and the abundance of monazite in the surrounding granites.Most minerals are partially and/or completely altered,which indicated by the pseudomorphism of zircon by xenotime,thorite,and uranothorite.展开更多
Low radioactive rare earth waste (containing 232 Th,specific activity 5 000 8 000 Bq·kg -1 ) were diluted 20 times by cement,sand and carbide ash and were made into special cement.The radioactivity of...Low radioactive rare earth waste (containing 232 Th,specific activity 5 000 8 000 Bq·kg -1 ) were diluted 20 times by cement,sand and carbide ash and were made into special cement.The radioactivity of this special cement complied with the healthy protect standard for radioactive materials (GB6566 86).Test results showed that this special cement could lower COD,the degradation rate increased as the time went on.In acidic medium,this special cement could remove E Coli effectively.Applying aeration and adding lumps of cement,the degradation of COD versus time complied with Logistic model through fitting by computer.The two “S” curves indicated that aeration and adding lumps of cement had synergistic action on sewage treatment.展开更多
目的评估低剂量碘-131在非远处转移性高危分化型甲状腺癌(DTC)中的治疗效果。方法回顾分析了2008年1月至2013年6月在北京协和医院核医学科就诊的甲状腺癌患者电子病历,将满足以下条件的患者纳入研究:(1)DTC全切术后;(2)T4分期(肉眼见甲...目的评估低剂量碘-131在非远处转移性高危分化型甲状腺癌(DTC)中的治疗效果。方法回顾分析了2008年1月至2013年6月在北京协和医院核医学科就诊的甲状腺癌患者电子病历,将满足以下条件的患者纳入研究:(1)DTC全切术后;(2)T4分期(肉眼见甲外侵犯);(3)清甲治疗前刺激性Tg≤5 ng/ml;(4)无远处转移。根据患者接受放射性碘治疗的剂量分为低剂量组(30 m Ci)(n=52)和高剂量组(100 m Ci)(n=51),比较两组患者的清甲成功率和无病生存率。结果低剂量组和高剂量组的清甲成功率分别为86.5%(45/52)和86.3%(44/51)(P=0.9688),无病生存率分别为97.4%(38/39)和97.5%(39/40)(P=0.9855),差异均无统计学意义。结论对于清甲前刺激性Tg较低(≤5 ng/ml)且不伴有远处转移的DTC,低剂量碘-131的清甲效果及无病生存状态与高剂量无明显差异。展开更多
基金supported by the“trategic Priority Research Program”of the Chinese Academy of Sciences(No.XDA10010800)the National Natural Science Foundation of China(No.12074318)。
文摘To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The radioactivity of the proposed hydrophone is strictly controlled by selecting pure raw materials, especially active piezoelectric ceramics. The electroacoustic performance of the hydrophone is improved by making structural optimization. High sensitivity and aimed directivity are achieved using 33-mode piezoelectric ceramic rings arranged in series and improvement in the radiating head of the Tonpilz hydrophone, respectively. All electroacoustic performances are studied through finite element analyses.The simulations indicate that the electroacoustic performances of the hydrophones in linear alkylbenzene-based liquid scintillator can be approximately predicted according to the results in water because their differences caused by two types of acoustic media, water and liquid scintillator, are known. The tests show that the hydrophone prototype can achieve a maximum sensitivity of-209.3dB and a beamwidth of 132.2° at a frequency of 143 kHz.In addition, eight hydrophones only contributed to a background radioactivity level of 26 ± 4 mHz in the neutrino analysis.
文摘The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,zircon,monazite,xenotime,columbite,fergusonite,and unknown rare earth elements(REEs)bearing minerals as well as cassiterite.Special emphasis on REE content of thorite,uranothorite,zircon and xenotime has been done to correlate them with the increase of uranium contents in these sediments.The key evidence for the presence lowtemperature alteration processes includes the presence of some zircon crystals as remnants after complete dissolution of the overgrowth zircon in severe acidic environment,the sulphur content,biogenic minerals,occurrence of unusual minerals as cassiterite pore filling in zircon,variation in the REEs content from the surrounding granites to the stream sediments and the abundance of monazite in the surrounding granites.Most minerals are partially and/or completely altered,which indicated by the pseudomorphism of zircon by xenotime,thorite,and uranothorite.
文摘Low radioactive rare earth waste (containing 232 Th,specific activity 5 000 8 000 Bq·kg -1 ) were diluted 20 times by cement,sand and carbide ash and were made into special cement.The radioactivity of this special cement complied with the healthy protect standard for radioactive materials (GB6566 86).Test results showed that this special cement could lower COD,the degradation rate increased as the time went on.In acidic medium,this special cement could remove E Coli effectively.Applying aeration and adding lumps of cement,the degradation of COD versus time complied with Logistic model through fitting by computer.The two “S” curves indicated that aeration and adding lumps of cement had synergistic action on sewage treatment.
文摘目的评估低剂量碘-131在非远处转移性高危分化型甲状腺癌(DTC)中的治疗效果。方法回顾分析了2008年1月至2013年6月在北京协和医院核医学科就诊的甲状腺癌患者电子病历,将满足以下条件的患者纳入研究:(1)DTC全切术后;(2)T4分期(肉眼见甲外侵犯);(3)清甲治疗前刺激性Tg≤5 ng/ml;(4)无远处转移。根据患者接受放射性碘治疗的剂量分为低剂量组(30 m Ci)(n=52)和高剂量组(100 m Ci)(n=51),比较两组患者的清甲成功率和无病生存率。结果低剂量组和高剂量组的清甲成功率分别为86.5%(45/52)和86.3%(44/51)(P=0.9688),无病生存率分别为97.4%(38/39)和97.5%(39/40)(P=0.9855),差异均无统计学意义。结论对于清甲前刺激性Tg较低(≤5 ng/ml)且不伴有远处转移的DTC,低剂量碘-131的清甲效果及无病生存状态与高剂量无明显差异。
