In this study,the theory of minimum detectable activity concentration(MDAC)for airborne gamma-ray spectrometry(AGS)was derived,and the relationship between the MDAC and the intrinsic effi-ciency of a scintillation cou...In this study,the theory of minimum detectable activity concentration(MDAC)for airborne gamma-ray spectrometry(AGS)was derived,and the relationship between the MDAC and the intrinsic effi-ciency of a scintillation counter,volume,and energy res-olution of scintillation crystals,and flight altitude of an aircraft was investigated.To verify this theory,experi-mental devices based on NaI and CeBr 3 scintillation counters were prepared,and the potassium,uranium,and thorium contents in calibration pads obtained via the stripping ratio method and theory were compared.The MDACs of AGS under different conditions were calculated and analyzed using the proposed theory and the Monte Carlo method.The relative errors found via a comparison of the experimental and theoretical results were less than 4%.The theory of MDAC can guide the work of AGS in probing areas with low radioactivity.展开更多
The diffusion and the activation of phosphorus in phosphorus and fluorine co-implanted Ge after being annealed by excimer laser are investigated.The results prove that the fluorine element plays an important role in s...The diffusion and the activation of phosphorus in phosphorus and fluorine co-implanted Ge after being annealed by excimer laser are investigated.The results prove that the fluorine element plays an important role in suppressing phosphorus diffusion and enhancing phosphorus activation.Moreover,the rapid thermal annealing process is utilized to evaluate and verify the role of fluorine element.During the initial annealing of co-implanted Ge,it is easier to form high bonding energy FnVm clusters which can stabilize the excess vacancies,resulting in the reduced vacancy-assisted diffusion of phosphorus.The maximum activation concentration of about 4.4 ×10^(20) cm^(-3) with a reduced diffusion length and dopant loss is achieved in co-implanted Ge that is annealed at a tailored laser fluence of 175 mJ/cm^(2).The combination of excimer laser annealing and co-implantation technique provides a reference and guideline for high level n-type doping in Ge and is beneficial to its applications in the scaled Ge MOSFET technology and other devices.展开更多
Terminalia bellericaRoxb. （Belleric myrobalan） is one of the important multipurpose trees in central India. The fruits of the tree are highly valued for medicinal uses, with the greatest demand coming from the pharm...Terminalia bellericaRoxb. （Belleric myrobalan） is one of the important multipurpose trees in central India. The fruits of the tree are highly valued for medicinal uses, with the greatest demand coming from the pharmaceutical industry. This has resulted in overexploitation and present harvesting practices have led to a significant decline in natural regeneration for this tree species. Our study was conducted from 2006 to 2009 in Chhattisgarh （India） to standardize suitable harvesting practices for sustainable management for this valuable species. Experiments were conducted at four different sites located in Dhamtari, Sarguja, and Rai-garh forest divisions of the state, covering both protected and open forest in a complete randomized block design （RCBD）. At each site, linear transects of 200 m× 100 m （2 ha） were randomly selected to sample the initial population and study the effects of two harvesting methods （tradi-tional and nondestructive） and four harvesting intensities （60%, 70%, 80%, and 90%） on the sustainability ofT. bellerica. Fruits were collected and analyzed for their tannin and gallic acid content. Significant increase in tannin and gallic acid content was found with the maturity of fruits （September to December）. This is the first study to experimentally assess the consequences of harvesting ofT. bellericafruits in central India. Our findings reveal that harvesting intensity, time, and method are key factors for maintaining the population. Nondestructive harvesting meth-ods were found to be superior to traditional harvesting in terms of regen-eration, recruitment, and concentration of active ingredients. When the fruits were harvested through non-destructive means at maturity, the population of species increased. The study concludes that 70% harvest of T. bellerica fruits through non-destructive means maintains the sustain-ability and provides quality raw material for the pharmaceutical industry.展开更多
基金This work was supported by the Sichuan Science and Technology Program(No.2020JDRC0108)the National Science Foundation of China(Nos.41774147 and 41774190).
文摘In this study,the theory of minimum detectable activity concentration(MDAC)for airborne gamma-ray spectrometry(AGS)was derived,and the relationship between the MDAC and the intrinsic effi-ciency of a scintillation counter,volume,and energy res-olution of scintillation crystals,and flight altitude of an aircraft was investigated.To verify this theory,experi-mental devices based on NaI and CeBr 3 scintillation counters were prepared,and the potassium,uranium,and thorium contents in calibration pads obtained via the stripping ratio method and theory were compared.The MDACs of AGS under different conditions were calculated and analyzed using the proposed theory and the Monte Carlo method.The relative errors found via a comparison of the experimental and theoretical results were less than 4%.The theory of MDAC can guide the work of AGS in probing areas with low radioactivity.
基金Project supported by the National Natural Science Foundation of China(Grant No.61904155)the Science and technology Project of Fujian Provincial Department of Education,China(Grant No.JAT200484)+1 种基金the Natural Science Foundation of Fujian Province,China(Grant No.2018J05115)the Scientific Research Projects of Xiamen University of Technology,China(Grant No.YKJCX2020078).
文摘The diffusion and the activation of phosphorus in phosphorus and fluorine co-implanted Ge after being annealed by excimer laser are investigated.The results prove that the fluorine element plays an important role in suppressing phosphorus diffusion and enhancing phosphorus activation.Moreover,the rapid thermal annealing process is utilized to evaluate and verify the role of fluorine element.During the initial annealing of co-implanted Ge,it is easier to form high bonding energy FnVm clusters which can stabilize the excess vacancies,resulting in the reduced vacancy-assisted diffusion of phosphorus.The maximum activation concentration of about 4.4 ×10^(20) cm^(-3) with a reduced diffusion length and dopant loss is achieved in co-implanted Ge that is annealed at a tailored laser fluence of 175 mJ/cm^(2).The combination of excimer laser annealing and co-implantation technique provides a reference and guideline for high level n-type doping in Ge and is beneficial to its applications in the scaled Ge MOSFET technology and other devices.
基金supported by a grant from the Chhattisgarh State Minor Forest Produce(Trading and Development)Co-operative Federation Ltd.,Raipur,India
文摘Terminalia bellericaRoxb. （Belleric myrobalan） is one of the important multipurpose trees in central India. The fruits of the tree are highly valued for medicinal uses, with the greatest demand coming from the pharmaceutical industry. This has resulted in overexploitation and present harvesting practices have led to a significant decline in natural regeneration for this tree species. Our study was conducted from 2006 to 2009 in Chhattisgarh （India） to standardize suitable harvesting practices for sustainable management for this valuable species. Experiments were conducted at four different sites located in Dhamtari, Sarguja, and Rai-garh forest divisions of the state, covering both protected and open forest in a complete randomized block design （RCBD）. At each site, linear transects of 200 m× 100 m （2 ha） were randomly selected to sample the initial population and study the effects of two harvesting methods （tradi-tional and nondestructive） and four harvesting intensities （60%, 70%, 80%, and 90%） on the sustainability ofT. bellerica. Fruits were collected and analyzed for their tannin and gallic acid content. Significant increase in tannin and gallic acid content was found with the maturity of fruits （September to December）. This is the first study to experimentally assess the consequences of harvesting ofT. bellericafruits in central India. Our findings reveal that harvesting intensity, time, and method are key factors for maintaining the population. Nondestructive harvesting meth-ods were found to be superior to traditional harvesting in terms of regen-eration, recruitment, and concentration of active ingredients. When the fruits were harvested through non-destructive means at maturity, the population of species increased. The study concludes that 70% harvest of T. bellerica fruits through non-destructive means maintains the sustain-ability and provides quality raw material for the pharmaceutical industry.
