环保型防氡、防辐射建筑材料研究进展

综合国内外文献介绍了氡和原子辐射的危害、致癌机理,部分建筑材料的氡和放射性情况以及防氡、防辐射的机理,并重点介绍了当前国内外防氡、防辐射建筑材料的研究进展,提出了可利用我国丰富的矿产资源如重晶石、石膏、沸石、以及各种工业废渣开发各种具有防氡、防辐射的功能微集料作为基元材料,制备能够吸收和屏蔽建筑材料所释放的氡气和辐射的环保型建筑涂料、砌筑水泥、各种瓷砖胶结剂以及墙体腻子等的建设性意见.     

建筑材料放射性现场检测

本文对影响建材表面γ空气比释动能率测量的几个因素作了研究，提出 了一种建材放射性现场检测力法和剂量限制要求，并对实验和理论计算结果进行了讨论，二者之间有较好的一致性。     

Radon Exhalation Rate Study of Sand Samples Collected from Sea Coast of Tirur,Kerala, India Using Track Etch Technique

The sand samples have been collecting from the sea coast (Unniyal beach) of Tirur of Malappuram district of Kerala state (India) by the grab sampling method. Radon exhalation rates have measured by “Sealed Can Technique” using LR-115 type II plastic track detector to estimate the health risk level in the environment. The value of radon activity varies from 444.44 to 2204.44 becquerel meter^?3 (Bq m^?3) with a geometric mean (G.M.)/standard deviation (S.D.) value of 1017.21 Bq m^?3/433.27. The value of mass exhalation rate for radon varies from 0.01 to 0.05 Bq kg^?1 h^?1 with a G.M./S.D. value of 0.024 Bq kg^?1 h^?1/0.010. The value of area exhalation rate for radon varies from 0.27 to 1.33 Bq m^?2 h^?1 with a G.M./S.D. value of 0.62 Bq m^?2 h^?1/0.26. The values of radon emanation ranged from 2.90?×?10^?3 to 2.98?×?10^?3 (%) with a G.M./S.D. value of 2.98?×?10^?3(%)/0.05. The alpha dose equivalent of the studied area is found and it varies from 0.68 to 1.66 milli sievert year^?1 (mSv yr^?1) with a G.M./S.D. value of 1.03 mSv yr^?1/0.24. Good positive correlation is observed between the effective radium content and area exhalation rate for sand samples. Therefore, the obtained result shows that this region is safe as for as the health risk effects of radium and radon exhalation rate are concerned.     

Natural radionuclides content and associated dose rates in fine-grained sediments from Patras-Rion sub-basins, Greece

The activity concentrations of the natural radionuclides (238)U, (226)Ra, (232)Th and (40)K were measured in soil samples collected from the Patras-Rion sub-basins (Southern Greece) and were found to be 28, 27, 30 and 483 Bq kg(-1), respectively. These values compare well with the average Greek and worldwide values for crustal soil and sedimentary rocks. The mean (226)Ra/(238)U activity ratio was close to 1, implying secular radioactive equilibrium in the uranium series. All soil samples have Ra(eq) values lower than the limit of 370 Bq kg(-1), indicating their safe use in brick production. The average annual terrestrial absorbed dose rate in air was 51±14 nGy h(-1), and the average annual effective dose 0.06±0.02 mSv y(-1), which is consistent with the average worldwide exposure to external terrestrial radiation outdoors (0.07 mSv y(-1)). Non-significant differences between soils with different age and depositional environments were found, which could be attributed to a common source of sediments.     

Amyloid Fibrils as Building Blocks for Natural and Artificial Functional Materials

Proteinaceous materials based on the amyloid core structure have recently been discovered at the origin of biological functionality in a remarkably diverse set of roles, and attention is increasingly turning towards such structures as the basis of artificial self‐assembling materials. These roles contrast markedly with the original picture of amyloid fibrils as inherently pathological structures. Here we outline the salient features of this class of functional materials, both in the context of the functional roles that have been revealed for amyloid fibrils in nature, as well as in relation to their potential as artificial materials. We discuss how amyloid materials exemplify the emergence of function from protein self‐assembly at multiple length scales. We focus on the connections between mesoscale structure and material function, and demonstrate how the natural examples of functional amyloids illuminate the potential applications for future artificial protein based materials.     

高酸性气田钻井中钻具的选材评价

以高含硫化氢聚合物钻井液为腐蚀介质,考察了温度、流速、pH值、PCO2/P2S分压比对S135和G105高强度钻杆钢的腐蚀影响,并对腐蚀产物形貌和成分进行了分析.结果表明,腐蚀速率随温度的升高而增大,在60～80℃间,腐蚀速率略有下降,温度超过120℃后,腐蚀速率变化不明显;流速对腐蚀速率影响不大;pH值越低,腐蚀越明显;在本试验范围内PCO2/PH2S分压比对腐蚀速率影响不大;气相腐蚀速率高于液相腐蚀速率,这与常规酸性钻井液中液相腐蚀速率高于气相腐蚀速率相反.硫化物应力腐蚀试验表明,钻杆强度越高其临界应力越低.钻杆的抗硫性能依次为G105(C)＞G105(D)＞S135(B)＞S135(A),此方法可为国内在开发高酸性气田时合理选取井下钻具管材提供参考.     

Investigation of Natural Radioactivity in Wadi El Reddah Stream Sediments and Its Radiological Implications

Radiochemistry - Wadi El Reddah has radiation exposure due to the presence of different types of complexed rocks along with a huge sector of Hammamat sedimentary rocks, monzongranites of Gabal El...     

Sub-Kelvin Thermal Conductivity and Radioactivity of Some Useful Materials in Low Background Cryogenic Experiments

We present measurements of the thermal conductivity between 0.05 and 1 K, and radioactive contamination levels, for some thermally isolating materials. TIMET Ti 15-3-3-3, Mersen grade 2020 graphite, Vespel SP-1, Vespel SP-22, Vespel SCP-5000, Vespel SCP-5050, Graphlite CFRP, and a Kapton/epoxy composite are all investigated. Thermal conductivities were measured using a single-heater longitudinal heat flow method. Material radioactivity was determined for the materials at a low background counting facility using a high-purity gamma detector and GEANT4 Monte Carlo simulations.