From photographic plate data of Shanghai Astronomical Observatory with a time baseline of 87 years, proper motions and membership probabilities of 364 stars in the open cluster NGC 6530 region are reduced. On the basi...From photographic plate data of Shanghai Astronomical Observatory with a time baseline of 87 years, proper motions and membership probabilities of 364 stars in the open cluster NGC 6530 region are reduced. On the basis of membership determination, luminosity function and segregation effect of the cluster are discussed with details. Spatial mass segregation is obviously present in NGC 6530 while there is no clear evidence for a velocity-mass （or velocity-luminosity）dependence. The observed spatial mass segregation for NGC 6530 might be due to a combination of initial conditions and relaxation process.展开更多
Introduction Because of the increasing use of phosphate in industries worldwide,especially in Togo,it is interesting to investigate the potential radioactivity exposure of phosphate ores,especially in the one being ex...Introduction Because of the increasing use of phosphate in industries worldwide,especially in Togo,it is interesting to investigate the potential radioactivity exposure of phosphate ores,especially in the one being exploring in Togo nowadays.Material and methods The contents of natural radionuclides(40K,226Ra,232Th,235U and 238U)were assessed in phosphate soil samples from Kpogamé,Dagbati and Kpéméin the maritime region of Togo by using gamma spectrometry-based Broad Energy Germanium detector(BEGe6530).Since no study was made prior to the exploitation,the samples from the control area of Anfoin-Kpota far away from the three others were considered as reference.Results and discussion The results are discussed and compared with the data from other countries.The activity concentration of 40K,226Ra,232Th,235U and 238U are between(59.45 and 129.99),(20.19 and 779.93),(16.81 and 121.42),(2.26 and 52.03)and(16.66 and 841.14)Bq kg^(−1),respectively.The values obtained shows that the exploitation sites(Dagbati and Kpogamé)and treatment site(Kpémé)have a very high level of radioactivity than the control area(Anfoin-Kpota).The Kpogaméand Dagbati exploitation and Kpéméwaste discharging phosphate deposit sites were found to have higher activity concentration than many others exploited phosphate sedimentary deposits around the world.The average annual effective dose of the above studied sites is 0.36,0.24 and 0.48 mSv year−1,respectively.The value related to the discharge waste site is about 2%of the 1.0 mSv year−1 recommended by the International Commission on Radiological Protection as the maximum annual dose to the public.Conclusions The obtained result of both radioactivity and radiological level in the studied areas will be considered as a pre-operational baseline to estimate the possible radiological impacts due to mining and processing phosphate industrial activities.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘From photographic plate data of Shanghai Astronomical Observatory with a time baseline of 87 years, proper motions and membership probabilities of 364 stars in the open cluster NGC 6530 region are reduced. On the basis of membership determination, luminosity function and segregation effect of the cluster are discussed with details. Spatial mass segregation is obviously present in NGC 6530 while there is no clear evidence for a velocity-mass （or velocity-luminosity）dependence. The observed spatial mass segregation for NGC 6530 might be due to a combination of initial conditions and relaxation process.
基金The authors wish to express their deep appreciation and gratitude to the IAEA for awarding the fellowship,without which this work would have been impossibleand the Director General of the National Radiation Protection Agency of Cameroon,Dr.Augustin SIMO for the laboratory support.The authors also appreciate the community of Hahotoé-Kpogaméfor the understanding during sampling period.They also wish to thank Dr.Michel WARNAU,Programme Management Officer for IAEA to Togo for his understanding and availability to this work.We also wish to address special thanks to Col.MANZI Pidalatan,National Liaison Officer of Togo and project coordinator of IAEA TC Project Number:TOG/0/002 provided in granting access to the facilities to successfully complete this study.
文摘Introduction Because of the increasing use of phosphate in industries worldwide,especially in Togo,it is interesting to investigate the potential radioactivity exposure of phosphate ores,especially in the one being exploring in Togo nowadays.Material and methods The contents of natural radionuclides(40K,226Ra,232Th,235U and 238U)were assessed in phosphate soil samples from Kpogamé,Dagbati and Kpéméin the maritime region of Togo by using gamma spectrometry-based Broad Energy Germanium detector(BEGe6530).Since no study was made prior to the exploitation,the samples from the control area of Anfoin-Kpota far away from the three others were considered as reference.Results and discussion The results are discussed and compared with the data from other countries.The activity concentration of 40K,226Ra,232Th,235U and 238U are between(59.45 and 129.99),(20.19 and 779.93),(16.81 and 121.42),(2.26 and 52.03)and(16.66 and 841.14)Bq kg^(−1),respectively.The values obtained shows that the exploitation sites(Dagbati and Kpogamé)and treatment site(Kpémé)have a very high level of radioactivity than the control area(Anfoin-Kpota).The Kpogaméand Dagbati exploitation and Kpéméwaste discharging phosphate deposit sites were found to have higher activity concentration than many others exploited phosphate sedimentary deposits around the world.The average annual effective dose of the above studied sites is 0.36,0.24 and 0.48 mSv year−1,respectively.The value related to the discharge waste site is about 2%of the 1.0 mSv year−1 recommended by the International Commission on Radiological Protection as the maximum annual dose to the public.Conclusions The obtained result of both radioactivity and radiological level in the studied areas will be considered as a pre-operational baseline to estimate the possible radiological impacts due to mining and processing phosphate industrial activities.
