Monte Carlo simulation of indoor external exposure due to gamma-emitting radionuclides in building materials

The use of building materials containing naturally occurring radionuclides such as^40K,^238U,^232Th and their progeny, could lead to external exposures to the residents of such buildings. In this paper, a set of models are constructed to calculate the specific effective dose rates（the effective dose rate per Bq/kg of ^40K, the ^238U series,and the ^232Th series） imposed on residents by building materials with the MCNPX code. The effect of chemical composition, position concerned in the room and thickness as well as density of material is analyzed. In order to facilitate more precise assessment of indoor external dose due to gamma-emitting radionuclides in building materials,three regressive expressions are proposed and validated by measured data to calculate specific effective rates for40 K,the238U series and the232 Th series, respectively.     

聚（1-乙烯基-3-乙酸烷基酯咪唑）阳离子／P（MMA．VAc）聚合物电解质

合成了一系列由聚（1-乙烯基-3-乙酸烷基酯咪唑）阳离子和二（三氟甲基磺酰亚胺）阴离子（TFSI）组成的聚离子液体并进行了表征．热重分析（TGA）和电导率分析表明,在聚（甲基丙烯酸甲酯,醋酸乙烯酯）（P（MMA—VAc））基体中掺杂聚离子液体后,体系的热稳定性和离子电导率均大为改善,红外光谱（FT—IR）、示差扫描量热分析（DSC）、X射线衍射（XRD）和扫描电子显微镜（SEM）等测试结果亦可佐证．讨论了离子液体的结构以及不同种锂盐（LiC104,LiBF4,LiTFSI）对电解质性能的影响．由PIL／P（MMA—VAc）／LiTFSI组成的共混电解质膜,在可见光下透过率≥90％,可作为离子导电材料用于电致变色器件（ECD）,显示了其优良的电化学性能．     

基于回收标志内不同数字代表塑料的单元整体教学*——以 “合成高分子”为例

以塑料回收标志内不同数字代表的塑料在生活中的用途为载体,辅助自制教具进行模型拼插,在对塑料回收标志内不同数字对应塑料的成分分析中,既落实了合成高分子的基本方法和高分子化合物在生活中的应用等学科知识,又培养了学生宏观辨识与微观探析的化学学科核心素养。     

亚纳秒脉冲传输线损耗分析

 脉冲传输线的介质材料选择和参数设计对传输线的损耗具有至关重要的影响，根据分布参数理论和电磁场微波理论，给出环氧玻璃纤维FR-4和聚四氟乙烯F₄B两种材料的损耗计算公式，在微带特性阻抗为50Ω，工作频率为10GHz时，FR-4和F₄B的介质衰减系数分别为0.095 dB/cm和0.0023dB/cm；当微带厚度为18μm，介质材料厚度为0.25mm时，FR-4和F₄B的导体衰减系数分别为0.0499dB/cm和0.0357dB/cm。数值计算和仿真结果表明，F₄B材料传输线的介质损耗和导体损耗相对较低，是一种较好的介质材料，选择合适的介质材料厚度可保证损耗较低且电路体积不至于过大。     

移动物体导热和表面辐射耦合问题的数值计算

本文以炉渣冷却为应用背景,对移动物体导热和表面辐射耦合问题进行数值模拟,探讨其数值模拟方法及传输带速度、炉渣厚度等相关因素对炉渣换热及温度变化的影响。计算结果表明,当炉渣量一定时,提高带速可使出口处炉渣温度降低;当渣层厚度不变时,提高带速,出口处炉渣温度提高。计算还表明,对这种具有表面辐射的移动物体,需采用上风差分,且表面辐射计算要采用亚松弛。     

2,5-二噻吩基吡咯衍生物的合成与应用研究进展

2,5-二噻吩基吡咯衍生物具有良好的环境稳定性和电化学性质,在光电子领域有广泛的应用前景.综述了2,5-二噻吩基吡咯衍生物中噻吩环和吡咯环上不同位置取代衍生物的合成方法,并对2,5-二噻吩基吡咯衍生物在电致变色器件、光电子器件、传感器等方面的应用进行了概述.     

ps脉冲传输线的多容性负载阻抗匹配模型和计算

 指出提高微带横截面取样速率的关键问题是传输线多容性负载阻抗匹配，根据分布参数理论和微波传输线理论，提出局部匹配模型，推导出阻抗匹配计算公式。数值模拟和电路仿真结果表明，局部补偿匹配法对不同工作频率下的多负载电容ps脉冲传输线均可进行较好的补偿，传输线上的各点取样波形失真度很小，补偿效果明显，可以提高微带横截面取样速率。     

Monte Carlo simulation of indoor external exposure due to gamma-emitting radionuclides in building materials

The use of building materials containing naturally occurring radionuclides,such as ⁴⁰K, ²³⁸U, ²³²Th and their progeny, could lead to external exposures to the residents of such buildings. In this paper, a set of models are constructed to calculate the specific effective dose rates (the effective dose rate per Bq/kg of ⁴⁰K, the ²³⁸U series, and the ²³²Th series) imposed on residents by building materials with the MCNPX code. The effect of chemical composition, position concerned in the room and thickness as well as density of material is analyzed. In order to facilitate more precise assessment of indoor external dose due to gamma-emitting radionuclides in building materials, three regressive expressions are proposed and validated by measured data to calculate specific effective rates for ⁴⁰K, the ²³⁸U series and the ²³²Th series, respectively.