Sand/dust test is one of the key projects to examine the environmental adaptability of ordnance equipment.In order to decrease the abrasion of test facility caused by the sand/dust particles,the particles contained in...Sand/dust test is one of the key projects to examine the environmental adaptability of ordnance equipment.In order to decrease the abrasion of test facility caused by the sand/dust particles,the particles contained in the airflowneed to be reclaimed effectively.Amathematical model of Useparator is established.The flowfield and the trajectories of particles inside the separator are obtained using a numerical simulation method,and the separation efficiency and pressure drop of separator with different rows of separate components are also obtained at various flowvelocities.The simulation results indicate that the efficiency of U inertia separator is affected by the flowvelocity evidently,and a reasonably designed separator can meet the requirement of the separation efficiency in particular situation.The results can be use as reference for the design and test of sand/dust separate systems.展开更多
The phenomenon of combustible dust explosions is present within many industries. Tests for explosibility of dust clouds per ASTM E1226 use a 20 L explosive chamber that places the combustible dust directly below the d...The phenomenon of combustible dust explosions is present within many industries. Tests for explosibility of dust clouds per ASTM E1226 use a 20 L explosive chamber that places the combustible dust directly below the dispersion nozzle which generates a thorough mixture for testing purposes. However, in the underground coal mining industry, there are a number of geologic, mining, and regulatory factors that change the deposition scheme of combustible coal dust. This causes the atmosphere of a coal mine to have a variable rock dust-coal dust mixture at the time of ignition. To investigate the impact of this variable atmosphere, a series of lean explosibility tests were conducted on a sample of Pittsburgh Pulverized coal dust. These explosibility tests were conducted in a 38 L chamber with a 5 kJ Sobbe igniter. The 38 L chamber generates a variable air-dust mixture prior to ignition. The test results indicate that the 38 L chamber experiences reduced explosive pressures, and lower explosibility index values when compared to the 20 L chamber.展开更多
In a wood processing factory, the measured air concentration of birchen dust was 1. 26 ±0. 41 mg/m3, and the micronucleus frequency of peripheral blood lymphocytes in 83 workersexposed to wood dust was 1. 13 ...In a wood processing factory, the measured air concentration of birchen dust was 1. 26 ±0. 41 mg/m3, and the micronucleus frequency of peripheral blood lymphocytes in 83 workersexposed to wood dust was 1. 13 ± 2. 83%, which was significantly higher (P < 0.01 ) thanthat of control group (0. 51 ± 1. 41% ). The number of exposed workers with positive mi-cronucleus test was 9. 6 %, which was higher than that of control group (4. 5 % ), but thedifference was not significant (P >0. 05 ). The micronucleus test in mice treated with waterextracts of unsteamed and unbaked birchen dust showed that the micronucleus frequencies inall treated groups were significantly higher than that of contro group (P < 0. 01 ) and therewas also a doseresponse correlation (r = 0. 96, P < 0. 0005 ). The results of steamed andbaked birchen dust extracts were significantly lower than those of the unsteamed and unbakedones at the same doses (P< 0. 001 ). This suggests that when the birchen dust is steamed atthe temperature of 100℃ for 24h or baked at the temperature of 80℃, its inducing effect inmicronucleus test could be lowered展开更多
The purpose of this project is to control the pollution of dust,which occurred in a typical lead-zinc mine.Two kinds of surfactants and water glass were chosen as the wetting agents to study the behaviours of suppress...The purpose of this project is to control the pollution of dust,which occurred in a typical lead-zinc mine.Two kinds of surfactants and water glass were chosen as the wetting agents to study the behaviours of suppressing the dust.The performances of the wetting agents of various sizes and water content of dust and their compositions among different weting agents were investigated. Firstly,the chemical compounds,dispersity,water content,bulk density and other relevant physico-chemical properties of the choiced dust of lead-zinc ore were mensurated.A great number of down-ward penetrating tests were conducted to different partical sizes of dust and to analyze the dust wetting behaviour respectively.The optimal compositions of wetting agents were obtained in accordance with different water contents and partical sizes of the dust after analyzing and statisting the achieved experimental data. The data show that the efficiency of chemical dust suppression of weting agents is much better than that of water.The results of the research work prove that the partical size and the water content of the dust are very important factors to the dust suppression.The results are also proved validly by the dropping experiment,which takes the penetrating diameter and penetrating time as the major factors.The superfine dust is much more difficult to be wetted.Since increasing the water content of dust is the best approach to control it,the choice of wetting agents for improving dispensation is significant.展开更多
To more reasonably evaluate human intake of PBDEs via dust ingestion, bioaccessibility should be taken into account. Previously, we developed an in vitro method to determine the bioaccessibility of PBDEs in food. Here...To more reasonably evaluate human intake of PBDEs via dust ingestion, bioaccessibility should be taken into account. Previously, we developed an in vitro method to determine the bioaccessibility of PBDEs in food. Here, this method was adapted to determine the bioaccessibility of PBDEs in dust and the digestion conditions that influenced the bioaccessibility of PBDEs were optimized. The digestion conditions included the incubation time of dust in the intestinal digestion solution （T）, the bile concentration in the intestinal digestion solution （Chile）, and the ratio of the volume of the intestinal digestion solution to dust （R）. The influence of the concentrations of individual PBDE congeners （CpBDE） on the bioaccessibility of PBDEs was also investigated. Cetral composite design was used to build an experimental model and set experimental parameters, and response surface methodology was used to analyze the obtained data. The results showed that the bioaccessibility of PBDEs increased with the increases of Chile and R, and was independent of T and CpSDE. Under the digestion conditions with Chile and R being at 4.0-7.0 g/L and 150-250, respectively, the bioaccessibility of PBDEs in the method-dust varied from 39.2% to 72.8%, which were comparable with the bioaccessibility or bioavailability of PBDEs in dust/soil in the literature. Thus, the in vitro method to measure the bioaccessibility of PBDEs in dust was established and validated. Finally, the bioaccessibility of PBDEs in four natural dust samples, which ranged from 36.1% to 43.3%, were determined using the adapted method.展开更多
Metallic corrosion is a serious problem in the application of a hygroscopic inorganic dust-depressor. The basic characteristics of a hygroscopic inorganic dust-depressor and its corrosivity, corrosion mechanism, as we...Metallic corrosion is a serious problem in the application of a hygroscopic inorganic dust-depressor. The basic characteristics of a hygroscopic inorganic dust-depressor and its corrosivity, corrosion mechanism, as well as the principle of corrosion inhibition were analyzed. The static mass-loss test was carried out to investigate the corrosion behavior and the effect of the dust-depressor. The static corrosion rates of steel specimens were measured in six different corrosion inhibitor solutions of the dust-depressor, and the suitable corrosion inhibitors for the dust-depressor to reduce the corrosivity were found out.展开更多
The most famous deserts exist in subtropical regions which is the direct outcome of insufficient precipitation and high temperatures. The Middle East deserts are subjected often to dust, which reduces horizontal visib...The most famous deserts exist in subtropical regions which is the direct outcome of insufficient precipitation and high temperatures. The Middle East deserts are subjected often to dust, which reduces horizontal visibility to 5 km, and sometimes even to less than 100 m. The severe and prolong drought recently afflicting the west Asia region has been suggested to be instrumental in producing an increased output of dust into the atmosphere from the region. Regarding the increasing of dust events over the west of Iran with the external origin in the recent decade (from 2000 to present), so the main dust-source areas over Iraq and Syria have been detected using the dust-source map of the southwest of Asia, satellite images and soil type maps. We considered the relationship between the increasing of dust events in the western of Iran and drought expansion over the main dust-production areas during the recent decade. Dust frequency data series, and drought variables which include the VHI (vegetation health index), precipitation and temperature data series in long-term and monthly scales have been monitored and compared. And then we used the correlation analysis that indicated the significant proximity between the dust events and droughts/dryness in a yearly scale and also during the warm season (May to Aug). Meantime the derived results from the T-student test for the aforementioned data series confirm the fact that the droughts are parallel to the increasing of dust events from 1996 to 2011 (especially in the recent decade). We found that the recent droughts in the external dust source areas had the remarkable potential to increase the dust events in the west of Iran.展开更多
Despite wide application of hydrated calcium sulfate, possible respiratory effects of long-term occupational exposure to high concentrations of this chemical have only been investigated in a limited number of epidemio...Despite wide application of hydrated calcium sulfate, possible respiratory effects of long-term occupational exposure to high concentrations of this chemical have only been investigated in a limited number of epidemiological studies. This study is undertaken to examine this issue, more thoroughly. This cross-sectional study is carried out at a local gypsum plant in Shiraz, capital of Fars province situated in south western Iran. All exposed subjects (20 male workers) and 20 healthy non-exposed male individuals as the referent group are investigated. Prevalence of respiratory symptoms among the studied subjects is evaluated and they undergo spirometry test (twice for the exposed group and once for the unexposed employees). Moreover, to assess the extent to which workers are exposed to gypsum dust and using standard methods, inhalable and respirable fractions of this compound are measured in different dusty worksites. Average airborne concentration of inhalable dust fraction is estimated to be 24 ± 14.76 mg/m3 which is higher than the recommended threshold limit value (TLV) for this chemical. Respiratory symptoms such as phlegm, wheezing and dyspnea are significantly more prevalent in exposed subjects than in non-exposed employees (p < 0.05). The results of ventilatory function tests (pre- shift) don’t show any significant differences between both groups. However, some post-shift parameters of ventilatory function such as FVC, FEV1 and FEV1/FVC ratio are significantly lower than those of preshift and referent group. Exposure to high atmospheric concentrations of gypsum dust is associated with a significant increase in the prevalence of respiratory symptoms along with acute reversible significant decreases in some parameters of ventilatory function.展开更多
文摘Sand/dust test is one of the key projects to examine the environmental adaptability of ordnance equipment.In order to decrease the abrasion of test facility caused by the sand/dust particles,the particles contained in the airflowneed to be reclaimed effectively.Amathematical model of Useparator is established.The flowfield and the trajectories of particles inside the separator are obtained using a numerical simulation method,and the separation efficiency and pressure drop of separator with different rows of separate components are also obtained at various flowvelocities.The simulation results indicate that the efficiency of U inertia separator is affected by the flowvelocity evidently,and a reasonably designed separator can meet the requirement of the separation efficiency in particular situation.The results can be use as reference for the design and test of sand/dust separate systems.
文摘The phenomenon of combustible dust explosions is present within many industries. Tests for explosibility of dust clouds per ASTM E1226 use a 20 L explosive chamber that places the combustible dust directly below the dispersion nozzle which generates a thorough mixture for testing purposes. However, in the underground coal mining industry, there are a number of geologic, mining, and regulatory factors that change the deposition scheme of combustible coal dust. This causes the atmosphere of a coal mine to have a variable rock dust-coal dust mixture at the time of ignition. To investigate the impact of this variable atmosphere, a series of lean explosibility tests were conducted on a sample of Pittsburgh Pulverized coal dust. These explosibility tests were conducted in a 38 L chamber with a 5 kJ Sobbe igniter. The 38 L chamber generates a variable air-dust mixture prior to ignition. The test results indicate that the 38 L chamber experiences reduced explosive pressures, and lower explosibility index values when compared to the 20 L chamber.
文摘In a wood processing factory, the measured air concentration of birchen dust was 1. 26 ±0. 41 mg/m3, and the micronucleus frequency of peripheral blood lymphocytes in 83 workersexposed to wood dust was 1. 13 ± 2. 83%, which was significantly higher (P < 0.01 ) thanthat of control group (0. 51 ± 1. 41% ). The number of exposed workers with positive mi-cronucleus test was 9. 6 %, which was higher than that of control group (4. 5 % ), but thedifference was not significant (P >0. 05 ). The micronucleus test in mice treated with waterextracts of unsteamed and unbaked birchen dust showed that the micronucleus frequencies inall treated groups were significantly higher than that of contro group (P < 0. 01 ) and therewas also a doseresponse correlation (r = 0. 96, P < 0. 0005 ). The results of steamed andbaked birchen dust extracts were significantly lower than those of the unsteamed and unbakedones at the same doses (P< 0. 001 ). This suggests that when the birchen dust is steamed atthe temperature of 100℃ for 24h or baked at the temperature of 80℃, its inducing effect inmicronucleus test could be lowered
基金Project(50474050)supported by the National Natural Science Foundation of ChinaProject(20040533011)supported by the Doctorate Program Fund of Ministry of Education,China
文摘The purpose of this project is to control the pollution of dust,which occurred in a typical lead-zinc mine.Two kinds of surfactants and water glass were chosen as the wetting agents to study the behaviours of suppressing the dust.The performances of the wetting agents of various sizes and water content of dust and their compositions among different weting agents were investigated. Firstly,the chemical compounds,dispersity,water content,bulk density and other relevant physico-chemical properties of the choiced dust of lead-zinc ore were mensurated.A great number of down-ward penetrating tests were conducted to different partical sizes of dust and to analyze the dust wetting behaviour respectively.The optimal compositions of wetting agents were obtained in accordance with different water contents and partical sizes of the dust after analyzing and statisting the achieved experimental data. The data show that the efficiency of chemical dust suppression of weting agents is much better than that of water.The results of the research work prove that the partical size and the water content of the dust are very important factors to the dust suppression.The results are also proved validly by the dropping experiment,which takes the penetrating diameter and penetrating time as the major factors.The superfine dust is much more difficult to be wetted.Since increasing the water content of dust is the best approach to control it,the choice of wetting agents for improving dispensation is significant.
基金supported by the National Basic Research Program (973) of China (No. 2008CB418205)the Earmarked Fund of the State Key Laboratory of Organic Geochemistry (No. OGL-200903)+1 种基金the National Nature Science Foundation of China (No. 20807026,40830744)the Shanghai Leading Academic Disciplines (No. S30109)
文摘To more reasonably evaluate human intake of PBDEs via dust ingestion, bioaccessibility should be taken into account. Previously, we developed an in vitro method to determine the bioaccessibility of PBDEs in food. Here, this method was adapted to determine the bioaccessibility of PBDEs in dust and the digestion conditions that influenced the bioaccessibility of PBDEs were optimized. The digestion conditions included the incubation time of dust in the intestinal digestion solution （T）, the bile concentration in the intestinal digestion solution （Chile）, and the ratio of the volume of the intestinal digestion solution to dust （R）. The influence of the concentrations of individual PBDE congeners （CpBDE） on the bioaccessibility of PBDEs was also investigated. Cetral composite design was used to build an experimental model and set experimental parameters, and response surface methodology was used to analyze the obtained data. The results showed that the bioaccessibility of PBDEs increased with the increases of Chile and R, and was independent of T and CpSDE. Under the digestion conditions with Chile and R being at 4.0-7.0 g/L and 150-250, respectively, the bioaccessibility of PBDEs in the method-dust varied from 39.2% to 72.8%, which were comparable with the bioaccessibility or bioavailability of PBDEs in dust/soil in the literature. Thus, the in vitro method to measure the bioaccessibility of PBDEs in dust was established and validated. Finally, the bioaccessibility of PBDEs in four natural dust samples, which ranged from 36.1% to 43.3%, were determined using the adapted method.
文摘Metallic corrosion is a serious problem in the application of a hygroscopic inorganic dust-depressor. The basic characteristics of a hygroscopic inorganic dust-depressor and its corrosivity, corrosion mechanism, as well as the principle of corrosion inhibition were analyzed. The static mass-loss test was carried out to investigate the corrosion behavior and the effect of the dust-depressor. The static corrosion rates of steel specimens were measured in six different corrosion inhibitor solutions of the dust-depressor, and the suitable corrosion inhibitors for the dust-depressor to reduce the corrosivity were found out.
文摘The most famous deserts exist in subtropical regions which is the direct outcome of insufficient precipitation and high temperatures. The Middle East deserts are subjected often to dust, which reduces horizontal visibility to 5 km, and sometimes even to less than 100 m. The severe and prolong drought recently afflicting the west Asia region has been suggested to be instrumental in producing an increased output of dust into the atmosphere from the region. Regarding the increasing of dust events over the west of Iran with the external origin in the recent decade (from 2000 to present), so the main dust-source areas over Iraq and Syria have been detected using the dust-source map of the southwest of Asia, satellite images and soil type maps. We considered the relationship between the increasing of dust events in the western of Iran and drought expansion over the main dust-production areas during the recent decade. Dust frequency data series, and drought variables which include the VHI (vegetation health index), precipitation and temperature data series in long-term and monthly scales have been monitored and compared. And then we used the correlation analysis that indicated the significant proximity between the dust events and droughts/dryness in a yearly scale and also during the warm season (May to Aug). Meantime the derived results from the T-student test for the aforementioned data series confirm the fact that the droughts are parallel to the increasing of dust events from 1996 to 2011 (especially in the recent decade). We found that the recent droughts in the external dust source areas had the remarkable potential to increase the dust events in the west of Iran.
文摘Despite wide application of hydrated calcium sulfate, possible respiratory effects of long-term occupational exposure to high concentrations of this chemical have only been investigated in a limited number of epidemiological studies. This study is undertaken to examine this issue, more thoroughly. This cross-sectional study is carried out at a local gypsum plant in Shiraz, capital of Fars province situated in south western Iran. All exposed subjects (20 male workers) and 20 healthy non-exposed male individuals as the referent group are investigated. Prevalence of respiratory symptoms among the studied subjects is evaluated and they undergo spirometry test (twice for the exposed group and once for the unexposed employees). Moreover, to assess the extent to which workers are exposed to gypsum dust and using standard methods, inhalable and respirable fractions of this compound are measured in different dusty worksites. Average airborne concentration of inhalable dust fraction is estimated to be 24 ± 14.76 mg/m3 which is higher than the recommended threshold limit value (TLV) for this chemical. Respiratory symptoms such as phlegm, wheezing and dyspnea are significantly more prevalent in exposed subjects than in non-exposed employees (p < 0.05). The results of ventilatory function tests (pre- shift) don’t show any significant differences between both groups. However, some post-shift parameters of ventilatory function such as FVC, FEV1 and FEV1/FVC ratio are significantly lower than those of preshift and referent group. Exposure to high atmospheric concentrations of gypsum dust is associated with a significant increase in the prevalence of respiratory symptoms along with acute reversible significant decreases in some parameters of ventilatory function.
