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61.
Selcen Uzun Duran Belgin Kucukomeroglu Halim Taskin Necati Celik Uğur Cevik 《Isotopes in environmental and health studies》2017,53(1):91-103
The current study presents the results of the activity of radionuclides in spa waters, and evaluates their radiological influences on the population consuming these waters in the Central and Eastern Black Sea regions of Turkey. Since these waters are used for therapy and consumption purposes unconsciously, their radiological impact on the people was computed by taking into consideration the annual intake through ingestion of 226Ra, 232Th, 40K, 137Cs and 222Rn. The mean activities were estimated to be 11.35 for gross alpha, 6.23 for gross beta, 2.96 for 226Ra, 0.42 for 232Th, 0.069 for 137Cs, 0.19 for 40K, and 267 Bq L–1 for 222Rn, respectively. The estimated effective doses from spa water were found to be 49.77 µSv a–1 (226Ra), 5.95 µSv a–1 (232Th), 0.07 µSv a–1 (137Cs), 0.83 µSv a–1 (40K) and 56.03 µSv a–1 (222Rn). These values were evaluated and compared with related verified values from literature. Also, physico-chemical characterizations of spa water samples considered in the current study were investigated. This study would be useful for consumers and official authorities for the assessment of radiation exposure risk due to usage of the considered spa waters. 相似文献
62.
Dagmara I. Strumińska-Parulska 《Isotopes in environmental and health studies》2017,53(2):111-115
The idea behind this study was to investigate the most popular magnesium dietary supplements as a potential additional source of 210Pb in the human diet. The paper presents the results of 210Pb activities determined in different magnesium supplements, as well as an estimation of the annual effective radiation doses from 210Pb decay. The results showed that the highest value of 210Pb activity was found in a magnesium supplement of natural origin (dolomite) with a value of 2.97?±?0.18 mBq g–1. The highest annual radiation dose from 210Pb obtained from the magnesium daily recommended value (0.4 g of pure Mg) was calculated for dolomite tablets as 3.71?±?0.02 µSv·year–1. 相似文献
63.
A dc electric field is utilized to steer the electron motion after the molecular ion H_2~+ is excited by an ultrashort ultraviolet laser pulse. The numerical simulation shows that the electron localization distribution and the dissociation control ratio are dependent on the polarization direction and amplitude of the dc electric field. Most electrons of the dissociation state move opposite to the dc electric field and stabilize at the dressed-up potential well, for the dressed-down well is occupied by the electrons of the 1 sσ_g state. 相似文献
64.
Dual solutions in boundary layer flow of a moving fluid over a moving permeable surface in presence of prescribed surface temperature and thermal radiation 下载免费PDF全文
Swati Mukhopadhyay 《中国物理 B》2014,23(1):14702-014702
An analysis of the heat transfer for a boundary layer forced convective flow past a moving permeable flat surface parallel to a moving fluid is presented. Prescribed surface temperature at the boundary is considered. A thermal radiation term in the energy equation is considered. The similarity solutions for the problem are obtained and the reduced ordinary differential equations are solved numerically. To support the validity of the numerical results, a comparison is made with the available results for some particular cases of this study. Dual solutions exist when the surface and the fluid move in the opposite directions. 相似文献
65.
高效率LD端面抽运准连续355nm激光器 总被引:1,自引:0,他引:1
报道了一台激光二极管(LD)端面抽运Nd∶YVO4晶体腔内倍频和腔外和频相结合的声光调Q准连续355 nm紫外激光器。采用LD端面抽运双侧翼键合YVO4基质的Nd∶YVO4晶体,在腔内置入Ⅰ类相位匹配的LiB3O5(LBO)晶体进行倍频实现1 064 nm和532 nm双波长准连续激光输出,通过消色差透镜将双波长激光聚焦耦合到Ⅱ类相位匹配的LBO晶体中进行和频,并采用双向和频光路,获得了高效率、高光束质量、高重复频率的准连续355 nm紫外激光输出。在抽运功率为28.6 W、重复频率为20 kHz时,355 nm激光最大输出功率4.2 W,脉宽为20.6 ns,光-光转换效率为14.7%,激光器光束质量因子Mx2和My2分别为1.29和1.23。 相似文献
66.
67.
为了满足极端紫外波段微通道位敏阳极光子计数探测器研究的需要,研究了碱卤化物光阴极材料的量子效率.由于光阴极材料的光电发射电流主要是由次级电子形成的,给出碱卤化物光阴极材料次级电子发射的理论模型,推导出次级电子产出的计算公式,针对光子能量30—250 eV范围内,计算并分析了光阴极材料厚度和光入射角对次级电子产出的影响.分析结果显示,光阴极材料厚度大于100 nm并且掠入射角大于临界角,是获得高次级电子产出的最佳条件.最后,应用推导的公式分析20种碱卤化物在能量30—250 eV范围内次级电子产出的光谱响应
关键词:
极端紫外
碱卤化物
光阴极
次级电子 相似文献
68.
In this paper, we derive the time dependent solution of the effective master equation for the reduced density matrix operator of a two-level atom driven by a strong classical field and damped into a “modelled” reservoir with non-flat density of modes. The effects of different parameters on the atomic inversion, the von Neumann entropy and the entropy squeezing are discussed. 相似文献
69.
The surface of cyclo-olefin polymer (COP) was treated with vacuum ultraviolet (VUV) light at 172 nm wavelength to improve the wettability and adhesion properties. Through VUV treatment in air, the terminal groups of the COP surface were oxidized into oxygen functional groups, containing CO, CO, and COO components, making the COP surface hydrophilic. The extent of oxygenation was evaluated by XPS and FTIR-ATR spectra, and it was shown that the surface properties, hydrophilicity, and functionalization were dependent on both VUV irradiation distance and irradiation time, which have an effect on the concentration of oxygen functional groups. VUV-light treatment with a short irradiation distance was more effective in introducing oxygen functional groups. 相似文献
70.
由于空间环境中宇宙辐射无处不在,工作在空间环境的光纤系统必须考虑辐致损伤特性。建立了10GHz的射频光纤链路传输系统,分别采用单模光纤和保偏光纤作为传输媒质。利用60 Co`γ射线源,在剂量率1rad/s总剂量50krad下,对射频光纤链路进行辐照实验,对两种系统做对比分析。实验结果表明,单模光纤链路的辐致损耗绝对值较大,保偏光纤链路的辐致损耗绝对值较小;单模光纤的幂律模型指数较保偏光纤大,即同样的辐照剂量,单模光纤受影响程度大。在辐照起主要影响因素的阶段,单模光纤延时差受辐照影响程度较保偏光纤稍小。辐致损耗和辐致延时差对光纤长度都有线性累加作用。从整体水平看,50krad的辐射总剂量对两种光纤造成的损伤并不大,传输的信号仍在可用的范围之内。 相似文献