Volatile organic compounds(VOCs)are difficult to be eliminated safely and effectively because of their large concentration fluctuations.Thus,maintaining a stable concentration of VOCs is a significant study.In this re...Volatile organic compounds(VOCs)are difficult to be eliminated safely and effectively because of their large concentration fluctuations.Thus,maintaining a stable concentration of VOCs is a significant study.In this research,H2O,Tween-80,[Emim]BF4,[Emim]PF6,and[Hnmp]HSO4 were applied to absorb and desorb simulated VOCs.The ionic liquid[Emim]BF4 demonstrated the best performance and was thus selected for further experiments.As the ionic liquid acted as a buffer,the toluene concentration with a fluctuation of 2000–20000 mg·m-3 was stabilized at 6000–12000 mg·m-3.Heating distillation(90°C)was highly efficient to recover[Emim]BF4 from toluene.The regenerated[Emim]BF4 could retain its initial absorption capacity even after multiple cycles.Moreover,[Emim]BF4 had the same buffer function on various aromatic hydrocarbons.展开更多
The second most important cause of lung cancer after smoking is radon gas. Thus, the determination of indoor radon concentrations in residential buildings and workplaces is an important public health concern. The purp...The second most important cause of lung cancer after smoking is radon gas. Thus, the determination of indoor radon concentrations in residential buildings and workplaces is an important public health concern. The purpose of this research was to measure the concentration of radon gas in the offices of the Institute of Science and Technology and to evaluate the effective dose in the lungs and the risk of cancer. This study used Corentium’s AIR THINGS digital radon detector to determine the radon concentration in sixteen (16) offices. The digital radon detector air Things of Corentium was placed in each office for a minimum period of one week and the concentration values were recorded every 24 hours. The values recorded in each office were the short-term average and the long-term average during seven days of measurement. The short-term radon concentrations vary between 5.286 Bq/m<sup>3</sup> and 192.714 Bq/m3</sup> with an average of 48.01 Bq/m3</sup> and those in the long-term were between 6.143 Bq/m3</sup> and 172.571 Bq/m3</sup> with an average of 52.46 Bq/m3</sup>. The measurements in office N°6 and 13 were above the lower limit of 100 Bq/m3</sup> proposed by the WHO. The short-term and long-term effective doses in the lungs for offices N°6 and 13 were above the “normal” background level of 1.1 mSv/year proposed by UNSCEAR-2000. The short-term effective dose in the lungs for office N°6 was above the lower limit of 3 mSv per the ICRP-23 recommendation. The average number of lung cancer cases per year per million people was 15.展开更多
The activity concentrations of radionuclides, absorbed dose rate, excess lifetime cancer risk, and soil-to-plant transfer factor have been evaluated in soil and crop samples from Jalingo and Wukari Local Government Ar...The activity concentrations of radionuclides, absorbed dose rate, excess lifetime cancer risk, and soil-to-plant transfer factor have been evaluated in soil and crop samples from Jalingo and Wukari Local Government Area of Taraba State, Nigeria. The activity concentrations were determined with the aid of High Purity Germanium detector. The absorbed dose and excess lifetime cancer risk were evaluated and forecasted for 60 years using the ResRad off-site model. The average activity concentration of <sup>40</sup>K, <sup>232</sup>Th, and <sup>238</sup>U in the soil samples were 633.13, 141.15, and 71.20 Bq·kg<sup>-1</sup> respectively, for the Jalingo study area, and while that of the Wukari study area was;199.21, 87.23, and 25.37 Bq·kg<sup>-1</sup> respectively. The average soil-to-plant transfer factors for <sup>40</sup>K, <sup>232</sup>Th, and <sup>238</sup>U were 0.51, 0.10, and 0.27 respectively for the Jalingo study area while that of Wukari are 0.40, 0.57, and 0.74 respectively. The mean annual effective dose equivalent for the study area is higher than the world average of 0.07 mS·vy<sup>-1</sup>. The excess lifetime cancer risk for the study areas has values that are higher than the safety limit. The ResRed model showed that direct radiation from the crops is the major contributor to excess cancer risk among other pathways. The radiological hazard indices reveal health risks to farmers, especially in the Jalingo area.展开更多
The activity concentration of natural radioactivity for soil samples collected from western and mid Libyan regions were measured using HPGe detector. The average activity concentration of 226Ra, 232Th and 40K for ten ...The activity concentration of natural radioactivity for soil samples collected from western and mid Libyan regions were measured using HPGe detector. The average activity concentration of 226Ra, 232Th and 40K for ten regions was found to be 51.86 ± 7.14, 75.56 ± 10.95 and 128.98 ± 6.88 Bq/kg respectively. The results obtained for the corresponding nuclides 226Ra and 232Th are above the worldwide average values (35 and 30 Bq/kg) while 40K was smaller than worldwide average (400 Bq/kg). The average outdoor absorbed dose and the annual effective dose rates due to 226Ra, 232Th and 40K were observed to be 21.51 ± 2.93 nGy/h and 0.297 ±.03 mSv/y respectively, which are lower than world average values (60 nGy/h and 0.8 mSv/y). The radium equivalent activity and external hazard indices were found less than the world wide average values.展开更多
Igneous and sedimentary rocks contain an amount of natural radioactivity (NORM). U-238, Th-232 and their decay products, and K-40 are important sources of gamma-radiation. Knowledge of the radionuclide content of rock...Igneous and sedimentary rocks contain an amount of natural radioactivity (NORM). U-238, Th-232 and their decay products, and K-40 are important sources of gamma-radiation. Knowledge of the radionuclide content of rocks is necessary to estimate the exposure of the population to the radiation. Many types of rocks are used in building and industries, thus the radiation detection is important, it provides a baseline map of levels of the radioactivity in the study region. The purpose of this study is to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) (if found) in thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The samples were collected and prepared during 2018/2019, and analyzed with a good experimental instrument (High energy resolution γ-ray spectroscopy with HPGe detector), also these rock samples were analyzed with X-ray fluorescence to subdivided these rocks based on the major oxides proportions contained of each sample. The mean activity concentrations of naturally radionuclides were found in the igneous rock samples varied depending on the type of the igneous rock. For sedimentary rock samples, the activity concentrations were found high for quartz sandstone sample, which may be due to its high proportion of SiO<sub>2</sub> and K<sub>2</sub>O. The estimated mean values of absorbed dose rate are within the permissible limit value. The findings indicate high dose level values in granite (rhyolite) and most of diorite (andesite) igneous rock samples while gabbro (basalt) igneous rock samples (except for one sample) record low levels of dose rate. All sedimentary rock samples have low dose rate (except for the quartz sand-stone sample).展开更多
基金Supported by the Zhejiang University Students Science and Technology Innovation Activity Plan Funding(No.2018R403078).
文摘Volatile organic compounds(VOCs)are difficult to be eliminated safely and effectively because of their large concentration fluctuations.Thus,maintaining a stable concentration of VOCs is a significant study.In this research,H2O,Tween-80,[Emim]BF4,[Emim]PF6,and[Hnmp]HSO4 were applied to absorb and desorb simulated VOCs.The ionic liquid[Emim]BF4 demonstrated the best performance and was thus selected for further experiments.As the ionic liquid acted as a buffer,the toluene concentration with a fluctuation of 2000–20000 mg·m-3 was stabilized at 6000–12000 mg·m-3.Heating distillation(90°C)was highly efficient to recover[Emim]BF4 from toluene.The regenerated[Emim]BF4 could retain its initial absorption capacity even after multiple cycles.Moreover,[Emim]BF4 had the same buffer function on various aromatic hydrocarbons.
文摘The second most important cause of lung cancer after smoking is radon gas. Thus, the determination of indoor radon concentrations in residential buildings and workplaces is an important public health concern. The purpose of this research was to measure the concentration of radon gas in the offices of the Institute of Science and Technology and to evaluate the effective dose in the lungs and the risk of cancer. This study used Corentium’s AIR THINGS digital radon detector to determine the radon concentration in sixteen (16) offices. The digital radon detector air Things of Corentium was placed in each office for a minimum period of one week and the concentration values were recorded every 24 hours. The values recorded in each office were the short-term average and the long-term average during seven days of measurement. The short-term radon concentrations vary between 5.286 Bq/m<sup>3</sup> and 192.714 Bq/m3</sup> with an average of 48.01 Bq/m3</sup> and those in the long-term were between 6.143 Bq/m3</sup> and 172.571 Bq/m3</sup> with an average of 52.46 Bq/m3</sup>. The measurements in office N°6 and 13 were above the lower limit of 100 Bq/m3</sup> proposed by the WHO. The short-term and long-term effective doses in the lungs for offices N°6 and 13 were above the “normal” background level of 1.1 mSv/year proposed by UNSCEAR-2000. The short-term effective dose in the lungs for office N°6 was above the lower limit of 3 mSv per the ICRP-23 recommendation. The average number of lung cancer cases per year per million people was 15.
文摘The activity concentrations of radionuclides, absorbed dose rate, excess lifetime cancer risk, and soil-to-plant transfer factor have been evaluated in soil and crop samples from Jalingo and Wukari Local Government Area of Taraba State, Nigeria. The activity concentrations were determined with the aid of High Purity Germanium detector. The absorbed dose and excess lifetime cancer risk were evaluated and forecasted for 60 years using the ResRad off-site model. The average activity concentration of <sup>40</sup>K, <sup>232</sup>Th, and <sup>238</sup>U in the soil samples were 633.13, 141.15, and 71.20 Bq·kg<sup>-1</sup> respectively, for the Jalingo study area, and while that of the Wukari study area was;199.21, 87.23, and 25.37 Bq·kg<sup>-1</sup> respectively. The average soil-to-plant transfer factors for <sup>40</sup>K, <sup>232</sup>Th, and <sup>238</sup>U were 0.51, 0.10, and 0.27 respectively for the Jalingo study area while that of Wukari are 0.40, 0.57, and 0.74 respectively. The mean annual effective dose equivalent for the study area is higher than the world average of 0.07 mS·vy<sup>-1</sup>. The excess lifetime cancer risk for the study areas has values that are higher than the safety limit. The ResRed model showed that direct radiation from the crops is the major contributor to excess cancer risk among other pathways. The radiological hazard indices reveal health risks to farmers, especially in the Jalingo area.
文摘The activity concentration of natural radioactivity for soil samples collected from western and mid Libyan regions were measured using HPGe detector. The average activity concentration of 226Ra, 232Th and 40K for ten regions was found to be 51.86 ± 7.14, 75.56 ± 10.95 and 128.98 ± 6.88 Bq/kg respectively. The results obtained for the corresponding nuclides 226Ra and 232Th are above the worldwide average values (35 and 30 Bq/kg) while 40K was smaller than worldwide average (400 Bq/kg). The average outdoor absorbed dose and the annual effective dose rates due to 226Ra, 232Th and 40K were observed to be 21.51 ± 2.93 nGy/h and 0.297 ±.03 mSv/y respectively, which are lower than world average values (60 nGy/h and 0.8 mSv/y). The radium equivalent activity and external hazard indices were found less than the world wide average values.
文摘Igneous and sedimentary rocks contain an amount of natural radioactivity (NORM). U-238, Th-232 and their decay products, and K-40 are important sources of gamma-radiation. Knowledge of the radionuclide content of rocks is necessary to estimate the exposure of the population to the radiation. Many types of rocks are used in building and industries, thus the radiation detection is important, it provides a baseline map of levels of the radioactivity in the study region. The purpose of this study is to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) (if found) in thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The samples were collected and prepared during 2018/2019, and analyzed with a good experimental instrument (High energy resolution γ-ray spectroscopy with HPGe detector), also these rock samples were analyzed with X-ray fluorescence to subdivided these rocks based on the major oxides proportions contained of each sample. The mean activity concentrations of naturally radionuclides were found in the igneous rock samples varied depending on the type of the igneous rock. For sedimentary rock samples, the activity concentrations were found high for quartz sandstone sample, which may be due to its high proportion of SiO<sub>2</sub> and K<sub>2</sub>O. The estimated mean values of absorbed dose rate are within the permissible limit value. The findings indicate high dose level values in granite (rhyolite) and most of diorite (andesite) igneous rock samples while gabbro (basalt) igneous rock samples (except for one sample) record low levels of dose rate. All sedimentary rock samples have low dose rate (except for the quartz sand-stone sample).
