Elimination of phosphorus vaporizing from silicon was investigated. Si-P alloy made from electronic grade silicon was used. All the samples were analyzed by GD-MS. Theory calculation determines that phosphorus evapora...Elimination of phosphorus vaporizing from silicon was investigated. Si-P alloy made from electronic grade silicon was used. All the samples were analyzed by GD-MS. Theory calculation determines that phosphorus evaporates from molten silicon as gas species P and P2 at a finite reduced pressure. The experimental results show that phosphorus mass fraction can be decreased from 0.046% （460ppmw） to around 0.001% （10ppmw） under the condition of temperature 1 873 K, chamber pressure 0.6-0.8 Pa, holding time 1 h. Both experimental data and calculation results agree that at high phosphorus concentration, phosphorus removal is quite dependent on high chamber pressure while it becomes independent on low chamber pressure. The reason is that phosphorus evaporates from molten silicon as gas species P2 at a relatively high phosphorus concentration, while gas species P will be dominated in its vapour at low phosphorus content.展开更多
A vapor liquid equilibrium model and its related interactive energy parameters based on UNIQUAC model for the H2O-NH3-CO2 system without solid phase at the conditions of temperature from 30℃ to 90℃, pressure from 0....A vapor liquid equilibrium model and its related interactive energy parameters based on UNIQUAC model for the H2O-NH3-CO2 system without solid phase at the conditions of temperature from 30℃ to 90℃, pressure from 0.1 MPa to 0.4 MPa, and the maximum NH3 mass fraction up to 0.4 are provided. This model agrees with experimental data well (average relative error < 1%) and is useful for analysis of industrial urea production.展开更多
Inhalation of 222Rn progeny in the domestic environment contributes the greatest fraction of the natural radiation exposure to the public. The ultrafine activity of these progeny amounts up to about l 0 percent of the...Inhalation of 222Rn progeny in the domestic environment contributes the greatest fraction of the natural radiation exposure to the public. The ultrafine activity of these progeny amounts up to about l 0 percent of the total activity （attached and ultrafine）, but is considered to yield about 50 percent of the total radiation dose. Therefore, measurements of ultrafine fraction are essential for the estimation of radiation dose. The current study presents measured data on the total equilibrium equivalent concentration （EEC） and ultrafine equilibrium equivalent concentration （EECUn）, ultrafine fraction （fb）, attached and unattached activity size distributions of radon progeny in the low ventilated rooms at Minia University, Minia city, Egypt. A screen diffusion battery was used for collection the ultrafine fraction and measuring the total activity concentration of radon progeny. The attached activity size distribution of 214pb is determined by using a low pressure cascade impactor. The EEC of radon progeny varied between 1.3 and 18.9 Bq/m3 with a mean value of 5.2 ± 0.48 Bq/m2. The mean activity thermodynamic diameter （AMTD） ofultrafine of radon progeny was determined to be 1.26 nm with relative mean geometric standard deviations （GSD） of 1.3. The ultrafine fraction of radon progeny, fb, has a range 0.01 to 0.21 with an average of 0.08 ± 0.03. A relative mean GSD of 2.7 was determined for attached 2Lapb at a mean active median aerodynamic diameter （AMD） of 350 nm. Based on the above experimental results, the deposition fractions have been evaluated in each air way generation through the human lung by applying a lung deposition model. The bronchial deposition efficiencies of particles in the size range of attached radon progeny were found to be lower than those of ultrafine progeny. The effect of radon progeny deposition by adult male has been also studied for various levels of physical exertion. The dose conversion factor has been discussed as a function of fb.展开更多
基金Project (2007J0012) supported by the Natural Science Foundation of Fujian Province, ChinaProject (2007HZ0005-2) supported by the Key Technological Program of Fujian Province, ChinaProject (BASIC-10341702) supported by Norwegian Research Council
文摘Elimination of phosphorus vaporizing from silicon was investigated. Si-P alloy made from electronic grade silicon was used. All the samples were analyzed by GD-MS. Theory calculation determines that phosphorus evaporates from molten silicon as gas species P and P2 at a finite reduced pressure. The experimental results show that phosphorus mass fraction can be decreased from 0.046% （460ppmw） to around 0.001% （10ppmw） under the condition of temperature 1 873 K, chamber pressure 0.6-0.8 Pa, holding time 1 h. Both experimental data and calculation results agree that at high phosphorus concentration, phosphorus removal is quite dependent on high chamber pressure while it becomes independent on low chamber pressure. The reason is that phosphorus evaporates from molten silicon as gas species P2 at a relatively high phosphorus concentration, while gas species P will be dominated in its vapour at low phosphorus content.
文摘A vapor liquid equilibrium model and its related interactive energy parameters based on UNIQUAC model for the H2O-NH3-CO2 system without solid phase at the conditions of temperature from 30℃ to 90℃, pressure from 0.1 MPa to 0.4 MPa, and the maximum NH3 mass fraction up to 0.4 are provided. This model agrees with experimental data well (average relative error < 1%) and is useful for analysis of industrial urea production.
文摘Inhalation of 222Rn progeny in the domestic environment contributes the greatest fraction of the natural radiation exposure to the public. The ultrafine activity of these progeny amounts up to about l 0 percent of the total activity （attached and ultrafine）, but is considered to yield about 50 percent of the total radiation dose. Therefore, measurements of ultrafine fraction are essential for the estimation of radiation dose. The current study presents measured data on the total equilibrium equivalent concentration （EEC） and ultrafine equilibrium equivalent concentration （EECUn）, ultrafine fraction （fb）, attached and unattached activity size distributions of radon progeny in the low ventilated rooms at Minia University, Minia city, Egypt. A screen diffusion battery was used for collection the ultrafine fraction and measuring the total activity concentration of radon progeny. The attached activity size distribution of 214pb is determined by using a low pressure cascade impactor. The EEC of radon progeny varied between 1.3 and 18.9 Bq/m3 with a mean value of 5.2 ± 0.48 Bq/m2. The mean activity thermodynamic diameter （AMTD） ofultrafine of radon progeny was determined to be 1.26 nm with relative mean geometric standard deviations （GSD） of 1.3. The ultrafine fraction of radon progeny, fb, has a range 0.01 to 0.21 with an average of 0.08 ± 0.03. A relative mean GSD of 2.7 was determined for attached 2Lapb at a mean active median aerodynamic diameter （AMD） of 350 nm. Based on the above experimental results, the deposition fractions have been evaluated in each air way generation through the human lung by applying a lung deposition model. The bronchial deposition efficiencies of particles in the size range of attached radon progeny were found to be lower than those of ultrafine progeny. The effect of radon progeny deposition by adult male has been also studied for various levels of physical exertion. The dose conversion factor has been discussed as a function of fb.
