Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods...Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods.An abnormal radon exhalation behavior was observed,leading to computational fluid dynamics(CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered.Based on the in-situ experimental and numerical simulation results,variations in the radon exhalation rate subject to permeability,flow rate,and insertion depth were quantified and analyzed.The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method,which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements.The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air interface.The synergistic effects of the three factors(insertion depth,flow rate,and permeability)on the negative pressure difference and measured exhalation rate were quantified,and multivariate regression models were established,with positive correlations in most cases;the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^(−11) m^(2).CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.展开更多
Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the environment.Among these measurement methods,the closed-loop method is frequently used.However,traditional experim...Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the environment.Among these measurement methods,the closed-loop method is frequently used.However,traditional experiments are insufficient or cannot analyze the radon migration and exhalation patterns at the gas–solid interface in the accumulation chamber.The CFD-based technique was applied to predict the radon concentration distribution in a limited space,allowing radon accumulation and exhalation inside the chamber intuitively and visually.In this study,three radon exhalation rates were defined,and two structural ventilation tubes were designed for the chamber.The consistency of the simulated results with the variation in the radon exhalation rate in a previous experiment or analytical solution was verified.The effects of the vent tube structure and flow rate on the radon uniformity in the chamber;permeability,insertion depth,and flow rate on the radon exhalation rate and the effective diffusion coefficient on back-diffusion were investigated.Based on the results,increasing the inser-tion depth from 1 to 5 cm decreased the effective decay constant by 19.55%,whereas the curve-fitted radon exhalation rate decreased(lower than the initial value)as the deviation from the initial value increased by approximately 7%.Increasing the effective diffusion coefficient from 2.77×10^(-7) to 7.77×10^(-6) m^(2) s^(-1) made the deviation expand from 2.14 to 15.96%.The conclusion is that an increased insertion depth helps reduce leakage in the chamber,subject to notable back-diffusion,and that the closed-loop method is reasonably used for porous media with a low effective diffusion coefficient in view of the back-diffusion effect.The CFD-based simulation is expected to provide guidance for the optimization of the radon exhalation rate measurement method and,thus,the accurate measurement of the radon exhalation rate.展开更多
Radongas concentrations in soil samples were determined from depths (surface, 15, and 30) cm for nine locations in Al-Dora refinery and surrounding area using “sealed can technique” and CR-39 solid state nuclear tra...Radongas concentrations in soil samples were determined from depths (surface, 15, and 30) cm for nine locations in Al-Dora refinery and surrounding area using “sealed can technique” and CR-39 solid state nuclear track detectors. The radon concentration in surface samples ranged from 810.08 to 1380.08 Bq/m3 with an average 1137.71 Bq/m3. The radon concentration in soil at the depth 15 cm was ranged from 490.5 to 1197.52 Bq/m3 with an average 732.78 Bq/m3 and at the depth 30 cm was ranged from 362.07 to 889.53 Bq/m3 with an average 529.41 Bq/m3. The surface exhalation rate in surface soil samples ranged was 0.44, to 0.99 Bq·m-2·h-1 with average 0.61 Bq·m-2·h-1. The surface exhalation rate in soil samples at the depth 15 cm was ranged from 0.22 to 0.64 Bq·m-2·h-1 with average 0.39 Bq·m-2·h-1. The surface exhalation rate in soil samples at the depth 15 cm was ranged from 0.22 to 0.64 Bq·m-2·h-1 with average 0.39 Bq·m-2·h-1. The surface exhalation rate and the mass exhalation rate in soil samples at the depth 30 cm ranged from 0.19, to 0.48 Bq·m-2·h-1 with average 0.28 Bq·m-2·h-1. The mass exhalation rate in surface soil samples ranged from 0.09 to 0.21 Bq·kg-1·h-1 with average 0.12 Bq·kg-1·h-1. The mass exhalation rate in soil samples from depth 15 cm was ranged from 0.046 to 0.14 Bq·kg-1·h-1 with average 0.08 Bq·kg-1·h-1. The mass exhalation rate in soil samples at the depth 30 cm was ranged from 0.042 to 0.1 Bq·kg-1·h-1 with average 0.06 Bq·kg-1·h-1.展开更多
Coal is the main energy source for electricity generation in the world. In Morocco, 37% of electricity generation comes from combustion coal in thermal power plants. This combustion process generates large amounts of ...Coal is the main energy source for electricity generation in the world. In Morocco, 37% of electricity generation comes from combustion coal in thermal power plants. This combustion process generates large amounts of fly and bottom ashes. In recent years, these ashes became a great topic of interest because of their different uses and especially in construction materials. In this work, we assess radiation risks due to natural radioactivity in samples of fly and bottom ashes collected from JLEC (Jorf Lasfar Energy Company) thermal power plant, and different analyses are performed through two nuclear techniques such as gamma spectrometry and alpha dosimetry based on the use of LR115 films detectors. Our analysis shows that <sup>226</sup>Ra activities and <sup>232</sup>Th in both ash samples are well above the permissible activity. The values of the external risk index (H<sub>ex</sub>) and internal one (H<sub>in</sub>) for these ashes are below unity, with the exception of 1.28 in fly ash for H<sub>in</sub>. The obtained values for the equivalent radium Ra<sub>eq</sub> and annual effective doses Ėin fly and bottom ashes are 324 Bq/kg and 210 Bq/kg, and 0.18 mSv/y and 0.11 mSv/y, respectively. The surface radon exhalation rates for the samples of fly and bottom ashes are 276 mBq⋅m<sup>-2</sup>⋅h<sup>-1</sup> and 381 mBq⋅m<sup>-2</sup>⋅h<sup>-1</sup>, respectively. Based on these results, we have shown that fly ash and bottom one from thermal power plant JLEC didn’t have, in any case, a health risk to the public so it can be effectively used in various construction activities.展开更多
EPA-standardized activated charcoal canisters were used to collect radon exhaled from building surfaces and analyzed using γ-spectroscopy to obtain the radon exhalation rates. More than 120 samples were analyzed in m...EPA-standardized activated charcoal canisters were used to collect radon exhaled from building surfaces and analyzed using γ-spectroscopy to obtain the radon exhalation rates. More than 120 samples were analyzed in more than 10 buildings situated in different areas of Hong Kong. Variations were identified in the exhalation rates at different levels in a building, for different covering materials and for the presence of cracks in walls. The radon exhalation rate from the most common concrete walls and covering materials was found to be approximately 13 mBq·m<sup>-2</sup>·s<sup>-1</sup>. This may be the cause of a relatively high indoor radon concentration in Hong Kong.展开更多
Environmental radon emanates from the exhalation and release of soil,rocks,and building materials.Environmental radon contamination tracing and radon pollution prevention and control require the measurement of the rad...Environmental radon emanates from the exhalation and release of soil,rocks,and building materials.Environmental radon contamination tracing and radon pollution prevention and control require the measurement of the radon exhalation rate on media surfaces.Reliable measurements of the radon exhalation rate cannot be achieved without regular calibration of the measuring instrument with a high-performance reference device.In this study,a reference device for the calibration of radon exhalation rate measuring instruments was developed using a diffusion solid radon source with a high and stable radon emanation coefficient,an integrated diffusion component composed of a plasterboard and a high-density wooden board,an air pressure balance device,a radon accumulation chamber,and a support structure.The uniformity and stability of the reference device were evaluated using the activated carbon-γspectrum and open-loop method,respectively,to measure the radon exhalation rate.The reference device achieved different radon exhalation rates by using different activities of diffusion solid radon sources.Nineteen measurement points were regularly selected on the radon exhalation surface of the reference device,and the uniformity of the radon exhalation rate exceeded 5%.The short-term stability of the reference device was better than 5%under different environmental conditions and was almost unaffected by the ambient air pressure,environmental temperature,and relative humidity.展开更多
The assay of trace volatile low molecular weight(MW) compounds in human breath or in ambient atmosphere typically involves gas chromatography with flame ionization detection (FID). This paper introduced a direct assa...The assay of trace volatile low molecular weight(MW) compounds in human breath or in ambient atmosphere typically involves gas chromatography with flame ionization detection (FID). This paper introduced a direct assay which can overcome the difficulties of collection low concentration samples. In order to pre concentrate the trace low MW compounds, a small trapping column filled with absorbent must be used before thermal desorption of the collected samples onto chromatographic column(packed with Porapak Q) for separation. It has been proved that the characteristic of absorbent mainly influence the recoveries and the linear range of this method is from 0 05 ng to 5200 ng for pentane, methanol, ethanol and acetone.展开更多
Objective:To determine the radium-226 activity concentration,the massic radon exhalation rate and emanation factor of 55 soil samples from the Central Transdanubian Mountains in Hungary as well as possible radon exhal...Objective:To determine the radium-226 activity concentration,the massic radon exhalation rate and emanation factor of 55 soil samples from the Central Transdanubian Mountains in Hungary as well as possible radon exhalation hotspots in the sampling area were determined.Further indoor measurements are planned to investigate the possible exposure to radon of the inhabitants.Methods:The radium-226 activity concentration measurements were carried out with a semiconductor HPGe gamma-ray spectrometer.The massic radon exhalation rate and emanation factor were determined by measuring the radon activity concentrations using the accumulation method with a system developed by our department based on an AlphaGUARD DF2000 portable radon monitor.Results:The activity concentrations of radium-226 were between(11.42.5)and(118.23.0)Bq/kg,while their average was 39.51 Bq/kg.The massic radon exhalation rates were between(1.023.64)mBq⋅kg1⋅h1 and(275.634.05)mBq⋅kg1⋅h1,while their average was 39.51 mBq⋅kg1⋅h1.Finally,the emanation factors were between(0.010.04)and(0.800.03)with an average of 0.30.Conclusions:In our study,the results recorded from the bedrock at the sampling sites were analyzed.9 samples were taken from sites comprised of limestone bedrock,moreover,the average radium-226 activity concentrations and massic radon exhalation rates at these sampling sites were higher than average.It was also concluded that although no regional correlation can be seen from the results,a possible smaller radon hotspot was identified from our measurements where further sampling will be carried out.展开更多
Objective:To understand the characteristic parameters and radon exhalation rates of aerated concrete blocks.Methods:A total of 39 nationally inspected samples were measured.Their dry density was determined based on th...Objective:To understand the characteristic parameters and radon exhalation rates of aerated concrete blocks.Methods:A total of 39 nationally inspected samples were measured.Their dry density was determined based on their mass and volumes,their porosities were measured on the principle of volumetric expansion,and their radium content was determined using a high-purity germanium(HPGe)detector for gamma-ray spectroscopy.Furthermore,their diffusion lengths were quantified by establishing a combined cumulative and diffusion chamber,and their radon exhalation rates were measured through closed-box testing using a continuous radon monitor.Results:The aerated concrete blocks exhibited dry densities ranging from 464 to 840 kg/m^(3)[average:(654.0±82.5)kg/m^(3)],open porosities from 67.1%to 81.1%[average:(74.3±3.3)%],radium(^(226)Ra)content from 12.3 to 136 Bq/kg[average:(63.0±30.4)Bq/kg],diffusion lengths from 0.49 to 1.01 m[average:(0.70±0.15)m],and radon exhalation rates from 0.6 to 22.8 Bq·m^(-2)·h^(-1)[average:(7.3±5.3)Bq·m^(-2)·h^(-1)].Conclusion:Aerated concrete blocks exhibit significantly higher porosities,diffusion lengths,and radon exhalation rates than traditional concrete and clay bricks.These blocks might contribute to the high indoor radon concentration observed in modern buildings in China.展开更多
Objective:To develop a new system to accurately measure the radon exhalation from the latex pillows,and to estimate its potential exposure to users.Methods:The new system is composed of two loops,the first loop is des...Objective:To develop a new system to accurately measure the radon exhalation from the latex pillows,and to estimate its potential exposure to users.Methods:The new system is composed of two loops,the first loop is designed to trap background radon and thoron until their levels are nearly zero,and the second loop is the measurement loop to detect radon and thoron exhalation rates from the pillows.Results:The results showed that mass radon exhalation rated ranged from 0.18 Bq·kg^(-1)·h^(-1) to 0.78 Bq·kg^(-1)·h^(-1),with an average of(0.36±0.17)Bq·kg^(-1)·h^(-1) in the 9 samples.The average annual effective dose to users in a model room was estimated to be(15.51±12.69)μSv by assuming two pillows was used.Conclusion:These results demonstrate that the new system can effectively measure radon exhalation rates in latex pillows,and the potential exposure to radon exhalating from the pillows is very low.展开更多
Breath analysis can be used to diagnose diseases non-invasively.Accurate measurement of volatolomics is critical for breath analysis to be a gold standard.Tedlar bags(TB)are often used to collect breath samples,but th...Breath analysis can be used to diagnose diseases non-invasively.Accurate measurement of volatolomics is critical for breath analysis to be a gold standard.Tedlar bags(TB)are often used to collect breath samples,but they emit contaminants that affect accuracy.This issue was overlooked in previous studies.We found contamination issues with TB(e.g.,siloxanes and aromatic impurities)that affect the identification of volatile organic compounds(VOCs)due to impurities.Then,home-designed equipment(HD)made with poly-tetrafluoride(PTFE)and quartz glass for breath collection was developed and employed in clinical trials.15 healthy individuals and 32 non-small cell lung cancer(NSCLC)patients at IA stage participated in this study.610 VOCs can be collected through TB,which is less than HD(1109 VOCs),demonstrating that the inner wall of the TB easily adsorbs VOCs,leading to decreased detection concentrations.Otherwise,utilizing orthogonal partial least squares discriminant analysis(OPLS-DA),we identified chemical markers with significant discriminatory power(VIP>1.5,P<0.05).The HD method identified 12 target VOCs,surpassing the 3 target VOCs discerned by the TB method.A model combined with a machine learning algorithm for distinguishing early-stage lung cancer patients was established based on biomarkers,which were selected based on OPLS-DA.The results showed strong predictive capabilities for the HD-based model.It indicated that 12 biomarkers derived from the HD model were more effective in distinguishing NSCLC patients,with an AUC value of 0.92,compared to the AUC value of 0.5 from 3 markers obtained from the TB model.The sensitivity and specificity in the confusion matrix reached 100%and 80%for the HD test,but TB test reached only 40%and 60%.This work demonstrated that optimizing and standardizing VOCs collection methodology from breath of lung cancer patients is essential to identify actual volatiles,which could promote disease volatolomics worldwide.展开更多
The exploitation of the highly reliable gassensing device for exhaled acetone detection possesses momentous and capacious development prospects in the field of an early noninvasive diabetes diagnosis.Considering that ...The exploitation of the highly reliable gassensing device for exhaled acetone detection possesses momentous and capacious development prospects in the field of an early noninvasive diabetes diagnosis.Considering that the characteristics of crystal facets will impact the gas-sensitive performance,herein three different resistive gas sensors were successfully developed by utilizing the stable α-Fe_(2)O_(3)with different crystal facets as the sensitive materials.The gas-sensitive performance testing results reveal that the(110)crystal faceted α-Fe_(2)O_(3)sensor exhibits relatively superior comprehensive gas sensitivity toward acetone.Particularly,it is worth mentioning that the sensor demonstrates reliable sensitivity,rapid response(25 s)/recovery(3 s)speed,and strong anti-interference capability in detecting 2×10^(-6)acetone for the concentration threshold of diabetes,even when exposed to prolonged periods in variable environments.Furthermore,by simply validating the feasibility of the exhalation diagnosis using the as-prepared gas sensor,the(110)faceted α-Fe_(2)O_(3)gas sensor can effectively discriminate the states of healthy human exhalation and the simulated diabetic exhalation.Through integrating the experimental and theoretical analyses,the superior acetone-sensitive performance of the(110)facetedα-Fe_(2)O_(3)gas sensor can principally be interpreted in correlation with crystal facet-dependent gas adsorption capacity and defect-forming ability.These results not only imply a tremendous application perspective in monitoring acetone gas at sub-ppm concentration,but also open up an effective throughway to develop reliable gas-sensing devices for early non-invasive diabetes screening.展开更多
The concentration of the heavy isotope of hydrogen, deuterium (D), is not routinely measured in (human) medical laboratory tests, even though an increasing number of papers prove the pivotal role of D in tumor growth,...The concentration of the heavy isotope of hydrogen, deuterium (D), is not routinely measured in (human) medical laboratory tests, even though an increasing number of papers prove the pivotal role of D in tumor growth, cell cycle regulation, cell metabolism, and aging. Data from a prospective phase 2 clinical study and numerous retrospective clinical studies proved the anticancer effect of deuterium depletion achieved by replacing the regular water intake with deuterium-depleted water (DDW). In previous studies, the changes in serum D concentration of DDW-consuming patients were followed using blood samples and mass spectrometry, which was invasive, costly, and time-consuming. As future clinical trials will also require a follow-up of internal D level and the patient’s compliance, a new sampling device and procedure was developed based on condensing the exhaled breath water vapor and measuring its D content using a liquid water isotope laser analyzer. Test results showed that the device provided accurate, reliable, and reproducible data. According to the data, the internal D level in a person consuming normal water was stable. In contrast, exclusive consumption of DDW for several days resulted in a gradual decrease of D concentration in exhaled breath condensate (EBC), which was proportional to the D concentration of DDW. These data confirm that orally applied DDW equilibrates with the person’s water pool quickly, leading to a reduced internal D level reflected in the D content of EBC.展开更多
The Aqishan lead-zinc deposit,located in the Jueluotag metallogenic belt of eastern Tianshan,Xinjiang,Northwest China,has a stratiform occurrence in the marine volcanic tuff of the Yamansu Formation.The ore body has a...The Aqishan lead-zinc deposit,located in the Jueluotag metallogenic belt of eastern Tianshan,Xinjiang,Northwest China,has a stratiform occurrence in the marine volcanic tuff of the Yamansu Formation.The ore body has a typical double-layer structure,having a stratified,stratoid,lenticular upper part and a veined,stockwork-like lower part.The occurrence of the upper orebody is consistent with that of the volcanic tuff wall rock.The ore minerals are mainly chalcopyrite,pyrite,sphalerite,galena and magnetite,the altered minerals mainly being silicified,such as sericite,chlorite,epidote,garnet.The garnetized skarn,being stratiform and stratoid,is closely related to the upper part of the orebody.Geological observations show that the limestone in the ore-bearing Yamansu Formation is not marbleized and skarnized.Spatially,it is associated with the ferromanganese deposits in the marine volcanic rocks of the Yamansu Formation.These geological features reflect the likelihood that the Aqishan lead-zinc deposit is a hydrothermal exhalation sedimentary deposit.The results from the EPMA show that the garnet is mainly composed of grossular-andradite series,contents being in a range of 34.791-37.8%SiO_(2),32.493-34.274%CaO,8.454-27.275%FeO,0.012-15.293%Al_(2)O_(3),0.351-1.413%MnO,and lower values of 0.013-1.057%TiO_(2).The content of SiO_(2) vs.CaO and FeO vs.Al_(2)O_(3) has a significant positive correlation.The results of ICP-MS analysis for the garnet show that the REE pattern is oblique to right in general.The total amount of rare earth elements is relatively low,ΣREE=71.045-826.52 ppm,which is relatively enriched for LREE and depleted for HREE.LREE/HREE=8.66-4157.75,La_(N)/Yb_(N)=23.51-984.34,with obvious positive Eu and Ce anomalies(δEu=2.27-76.15,δCe=0.94-1.85).This result is similar to the REE characteristics of ore-bearing rhyolite volcanic rocks,showing that the garnet was formed in an oxidizing environment and affected by clear hydrothermal activity.The U-Pb isotopic dating of garnet by fs-LA-HR-ICP-MS gives an age of 316.3±4.4 Ma(MSWD=1.4),which is consistent with the formation time of the Yamansu Formation.According to the study of deposit characteristics and geochemical characteristics,this study concludes that the Aqishan lead-zinc deposit is a hydrothermal exhalation sedimentary deposit,the garnet being caused by hydrothermal exhalative sedimentation.展开更多
In this study, the activity concentrations of ^(226)Ra,^(232)Th,^(222)Rn, and ^(40)K, emanation fractions(P),equilibrium equivalent concentration(EEC), and mass exhalation rates(E_m) of radon released from building ma...In this study, the activity concentrations of ^(226)Ra,^(232)Th,^(222)Rn, and ^(40)K, emanation fractions(P),equilibrium equivalent concentration(EEC), and mass exhalation rates(E_m) of radon released from building materials used in Malaysia were studied using gamma-ray spectrometer with HPGe detector. Radiological parameters[activity concentration index(ACI), indoor air-absorbed dose rate(D_(in)), annual effective dose(AED_(in)) from external and internal(E_(Rn)), soft tissues(H_(ST)) and lung(H_L), and effective dose equivalent(H_(eff))] were estimated to evaluate radiological hazards due to the use of these building materials: sand, cement, gravel, bricks, tiles, fly ash, white cement, and ceramic raw materials. The measured P, EEC,and E_m vary from 10 to 30%, 0.9 to 22 Bq m^(-3), and 33 to 674 mBq h^(-1) kg^(-1), respectively, while the calculated ACI and AED_(in) vary from 0.1 ± 0.01 to 2.1 ± 0.1 and 0.1 ± 0.01 to 2.4 ± 0.6 mSv y^(-1), respectively. On the other hand, the internal annual effective dose ranges from 0.1 to 1.4 mSv y^(-1). The estimated radiological risk parameters were below the recommended maximum values, and radiological hazards associated with building materials under investigation are therefore negligible.展开更多
The aim of our present work is to measure the specific activities of the radionuclides 226Ra, 232Th, 40K and the exhalation rates in terms of area and mass of 222Rn in some samples of building materials commonly used ...The aim of our present work is to measure the specific activities of the radionuclides 226Ra, 232Th, 40K and the exhalation rates in terms of area and mass of 222Rn in some samples of building materials commonly used in Morocco in order to evaluate the radiological risk caused by natural radioactivity. To this end, the analyses were carried out, using two nuclear techniques, namely high resolution gamma spectrometry and alpha dosimetry based on the use of LR115, on 50 samples collected from large commercial suppliers in Morocco. The results of these analyses show that the average specific activities of 226Ra, 232Th and 40K in these materials vary from 9 to 52 Bq/kg, 3 to 63 Bq/kg and 68 to 705 Bq/kg respectively. These activities remain within the permissible limits of 35 Bq/kg, 30 Bq/kg and 370 Bq/kg respectively, with the exception of a few samples of red brick, gray cement, ceramic and granite. The activity of the radium equivalent (Raeq), the internal (Hin) and external (Hex) hazard indices, the absorbed dose rate, the total annual effective dose , the excess lifetime cancer risk (ELCR) as well as volumic activities, exhalation rates in terms of area (ES) and mass (EM) are calculated for the samples analyzed in this work in order to assess the radiological risks resulting from the use of these materials in various construction activities. It seems that the values of these indices vary from 19 to 196 Bq/kg, 0.08 to 0.67, 0.05 to 0.53, 9 to 91 nGy/h, 0.05 to 0.56 mSv/y, 0.19 × 10−3 to 1.96 × 10−3, 72 to 350 Bq/m3, 56 to 273 mBq⋅m−2⋅h−1 and 3 to 15 mBq⋅kg−1⋅h−1 respectively. The lowest values are identified for gypsum, while the highest are attributed to granite. All of the obtained results of these indices respect the permissible limits except for the Raeq in some granite samples, the ELCR index in all samples except gypsum and the radon volumic activity in some gray cement samples, ceramic and granite. As a result, the different types of building materials analyzed in our work do not present a health risk to the public and can be used in various construction activities, with the exception of a few samples of red brick, gray cement, ceramic and granite. The choice of the use of red brick, gray cement and ceramic should be monitored and adapted according to the criteria of the limitation of the doses whereas the use of the granite must be moderate in order to limit over time the health risk which increases with the duration of exposure of humans to these building materials.展开更多
The radiological impact of coal ashes, with enhanced natural radioactivity in the storage site, is due to the presence of naturally occurring radionuclides. Some of these radionuclides have a radioactive period of sev...The radiological impact of coal ashes, with enhanced natural radioactivity in the storage site, is due to the presence of naturally occurring radionuclides. Some of these radionuclides have a radioactive period of several million years and will, therefore, have time to migrate to the soil, atmospheric air, surface water, and groundwater. This impact depends mainly on the activity of these coal ashes, the duration of exposure to such waste, transfers to the air, and the leaching phenomenon by rainwater. In this study, and so as to assess the radiological impact of coal ashes of the storage site of the JLEC-Morocco thermal power plant on environment, some analyses are performed by alpha dosimetry and a digital dosimeter on samples of coal ashes, soil, atmospheric air, surface water and groundwater belonging to a perimeter of 10 km around that site. The obtained results show that, within the studied area, the radiological impact on the soil of the coal ashes of the storage site is insignificant even though the concentrations of radon in the near vicinity (1 to 2 km) are moderately important, and remain below 200 Bq/m3. In the atmospheric air, this impact remains medium for the neighborhoods of the storage site (2 to 3 km) with radon activities superior to 10 Bq/m3. These results also show that there may be a water contamination of wells located at the storage site without any transfer of radioactivity into the groundwater of the area studied where the concentrations of radon are less than 11.1 Bq/l.展开更多
The ore types of the Zhaokalong Fe-Cu deposit are divided into two categories： sulfide-type and oxide-type. The sulfide-type ore include siderite ore, galena-sphalerite ore and chalcopyrite ore, whereas the oxide-typ...The ore types of the Zhaokalong Fe-Cu deposit are divided into two categories： sulfide-type and oxide-type. The sulfide-type ore include siderite ore, galena-sphalerite ore and chalcopyrite ore, whereas the oxide-type ore include magnetite ore and hematite ore. The ore textures and structures indicate that the Zhaokalong deposit is of the sedimentary-exhalative mineralization type. Geochemical analyses show that the two ore types have a high As, Sb, Mn, Co and Ni content. The REE patterns reveal an enrichment of the LREE compared to the HREE. Isotopic analysis of siderite ore reveal that the j13CpDB ranges from -2.01 to 3.34 （%0） whereas the JISOsMow ranges from 6.96 to 18.95 （%0）. The fluid inclusion microthermometry results indicate that homogenization temperatures of fluid inclusions in quartz range from 131 to 181~C, with salinity values of 1.06 to 8.04 wt% NaCI eq. The mineralizing fluid therefore belongs to the low temperature - low salinity system, with a mineralizing solution of a CO2-Ca2＋（Na＋, K＋）-SO42- （F-, CI--H20 system. The geochemical results and fluid inclusion data provide additional evidence that the Zhaokalong deposit is a sedex-type deposit that experienced two stages of mineralization. The sulfide mineralization probably occurred first, during the sedimentary exhalative process, as exhibited by the abundance of marine materials associated with the sulfide ores, indicating a higher temperature and relatively deoxidized oceanic depositional environment. After the main exhalative stage, hydrothermal activity was superimposed to the sulfide mineralization. The later stage oxide mineralization occurred in a low temperature and relatively oxidized environment, in which magmatic fluid circulation was dominant.展开更多
Bronchial asthma is a common chronic airway inflammatory disease. Asthma is associated with high mortality, especially in the elderly patients. Repeated exacerbations cause disease progression. Therefore, identifying ...Bronchial asthma is a common chronic airway inflammatory disease. Asthma is associated with high mortality, especially in the elderly patients. Repeated exacerbations cause disease progression. Therefore, identifying the onset of acute elderly asthma as soon as possible and giving the effective treatment is crucial to improve the prognosis. This study was to investigate the significance of fractional exhaled nitric oxide （FeNO） combined with serum procalcitonin （PCT） and C-reactive protein （CRP） in the evaluation of elderly asthma. A total of 120 elderly patients with an acute attack of asthma from July, 2010 to May, 2012 were studied. On presentation, FeNO, serum PCT and CRP concentrations were measured and sputum culture was also performed. The elderly patients were re-evaluated when they had returned to their stable clinical state. The elderly patients were classified into two groups： positive bac- terial culture group （A） and negative bacterial culture group （B）. The results showed that： （1） In patients with an acute exacerbation of asthma, 48 （40%） patients had positive sputum bacterial culture and 72 （60%） had negative sputum bacterial culture. （2） The levels of FeNO in patients with acute exacerbation of asthma were significantly higher than in those with no acute exacerbation state （63.8±24.6 vs. 19±6.5 ppb, P〈0.05）. There was no significant difference in FeNO between group A and group B （P〉0.05）. （3） The levels of PCT and CRP in group A patients with an acute exacerbation of asthma were significantly higher （P〈0.05） than in group B （for PCT： 27.46±9.32 vs. 7.85±3.52 ng/mL; for CRP： 51.25±11.46 vs. 17.11±5.87 mg/L, respectively）. When they had returned to stable clinical state, the levels of PCT and CRP in group A were decreased significantly （P〈0.05）, and those in group B had no significant change （P〉0.05） when compared with the exacerbation group. There were no significant differences in the levels of PCT and CRP between the two groups in non-acute exacerbation state （/9〉0.05）. These results suggest that the increase in FeNO indicates the acute exacerbation of asthma, and the elevation of serum PCT and CRP levels may be associated with bacterial infection.展开更多
基金National Natural Science Foundation of China(No.11575080)Hunan Provincial Natural Science Foundation of China(No.2022JJ30482)Hunan Provincial Innovation Foundation for Postgraduate(No.QL20220206).
文摘Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods.An abnormal radon exhalation behavior was observed,leading to computational fluid dynamics(CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered.Based on the in-situ experimental and numerical simulation results,variations in the radon exhalation rate subject to permeability,flow rate,and insertion depth were quantified and analyzed.The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method,which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements.The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air interface.The synergistic effects of the three factors(insertion depth,flow rate,and permeability)on the negative pressure difference and measured exhalation rate were quantified,and multivariate regression models were established,with positive correlations in most cases;the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^(−11) m^(2).CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.
基金This work was supported by the National Natural Science Foundation of China(No.11575080)the National Natural Science Foundation of Hunan Province,China(No.2022JJ30482)the Hunan Provincial Innovation Foundation for Postgraduates(No.QL20220206).
文摘Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the environment.Among these measurement methods,the closed-loop method is frequently used.However,traditional experiments are insufficient or cannot analyze the radon migration and exhalation patterns at the gas–solid interface in the accumulation chamber.The CFD-based technique was applied to predict the radon concentration distribution in a limited space,allowing radon accumulation and exhalation inside the chamber intuitively and visually.In this study,three radon exhalation rates were defined,and two structural ventilation tubes were designed for the chamber.The consistency of the simulated results with the variation in the radon exhalation rate in a previous experiment or analytical solution was verified.The effects of the vent tube structure and flow rate on the radon uniformity in the chamber;permeability,insertion depth,and flow rate on the radon exhalation rate and the effective diffusion coefficient on back-diffusion were investigated.Based on the results,increasing the inser-tion depth from 1 to 5 cm decreased the effective decay constant by 19.55%,whereas the curve-fitted radon exhalation rate decreased(lower than the initial value)as the deviation from the initial value increased by approximately 7%.Increasing the effective diffusion coefficient from 2.77×10^(-7) to 7.77×10^(-6) m^(2) s^(-1) made the deviation expand from 2.14 to 15.96%.The conclusion is that an increased insertion depth helps reduce leakage in the chamber,subject to notable back-diffusion,and that the closed-loop method is reasonably used for porous media with a low effective diffusion coefficient in view of the back-diffusion effect.The CFD-based simulation is expected to provide guidance for the optimization of the radon exhalation rate measurement method and,thus,the accurate measurement of the radon exhalation rate.
文摘Radongas concentrations in soil samples were determined from depths (surface, 15, and 30) cm for nine locations in Al-Dora refinery and surrounding area using “sealed can technique” and CR-39 solid state nuclear track detectors. The radon concentration in surface samples ranged from 810.08 to 1380.08 Bq/m3 with an average 1137.71 Bq/m3. The radon concentration in soil at the depth 15 cm was ranged from 490.5 to 1197.52 Bq/m3 with an average 732.78 Bq/m3 and at the depth 30 cm was ranged from 362.07 to 889.53 Bq/m3 with an average 529.41 Bq/m3. The surface exhalation rate in surface soil samples ranged was 0.44, to 0.99 Bq·m-2·h-1 with average 0.61 Bq·m-2·h-1. The surface exhalation rate in soil samples at the depth 15 cm was ranged from 0.22 to 0.64 Bq·m-2·h-1 with average 0.39 Bq·m-2·h-1. The surface exhalation rate in soil samples at the depth 15 cm was ranged from 0.22 to 0.64 Bq·m-2·h-1 with average 0.39 Bq·m-2·h-1. The surface exhalation rate and the mass exhalation rate in soil samples at the depth 30 cm ranged from 0.19, to 0.48 Bq·m-2·h-1 with average 0.28 Bq·m-2·h-1. The mass exhalation rate in surface soil samples ranged from 0.09 to 0.21 Bq·kg-1·h-1 with average 0.12 Bq·kg-1·h-1. The mass exhalation rate in soil samples from depth 15 cm was ranged from 0.046 to 0.14 Bq·kg-1·h-1 with average 0.08 Bq·kg-1·h-1. The mass exhalation rate in soil samples at the depth 30 cm was ranged from 0.042 to 0.1 Bq·kg-1·h-1 with average 0.06 Bq·kg-1·h-1.
文摘Coal is the main energy source for electricity generation in the world. In Morocco, 37% of electricity generation comes from combustion coal in thermal power plants. This combustion process generates large amounts of fly and bottom ashes. In recent years, these ashes became a great topic of interest because of their different uses and especially in construction materials. In this work, we assess radiation risks due to natural radioactivity in samples of fly and bottom ashes collected from JLEC (Jorf Lasfar Energy Company) thermal power plant, and different analyses are performed through two nuclear techniques such as gamma spectrometry and alpha dosimetry based on the use of LR115 films detectors. Our analysis shows that <sup>226</sup>Ra activities and <sup>232</sup>Th in both ash samples are well above the permissible activity. The values of the external risk index (H<sub>ex</sub>) and internal one (H<sub>in</sub>) for these ashes are below unity, with the exception of 1.28 in fly ash for H<sub>in</sub>. The obtained values for the equivalent radium Ra<sub>eq</sub> and annual effective doses Ėin fly and bottom ashes are 324 Bq/kg and 210 Bq/kg, and 0.18 mSv/y and 0.11 mSv/y, respectively. The surface radon exhalation rates for the samples of fly and bottom ashes are 276 mBq⋅m<sup>-2</sup>⋅h<sup>-1</sup> and 381 mBq⋅m<sup>-2</sup>⋅h<sup>-1</sup>, respectively. Based on these results, we have shown that fly ash and bottom one from thermal power plant JLEC didn’t have, in any case, a health risk to the public so it can be effectively used in various construction activities.
文摘EPA-standardized activated charcoal canisters were used to collect radon exhaled from building surfaces and analyzed using γ-spectroscopy to obtain the radon exhalation rates. More than 120 samples were analyzed in more than 10 buildings situated in different areas of Hong Kong. Variations were identified in the exhalation rates at different levels in a building, for different covering materials and for the presence of cracks in walls. The radon exhalation rate from the most common concrete walls and covering materials was found to be approximately 13 mBq·m<sup>-2</sup>·s<sup>-1</sup>. This may be the cause of a relatively high indoor radon concentration in Hong Kong.
基金supported by the National Natural Science Foundation of China(No.11875165).
文摘Environmental radon emanates from the exhalation and release of soil,rocks,and building materials.Environmental radon contamination tracing and radon pollution prevention and control require the measurement of the radon exhalation rate on media surfaces.Reliable measurements of the radon exhalation rate cannot be achieved without regular calibration of the measuring instrument with a high-performance reference device.In this study,a reference device for the calibration of radon exhalation rate measuring instruments was developed using a diffusion solid radon source with a high and stable radon emanation coefficient,an integrated diffusion component composed of a plasterboard and a high-density wooden board,an air pressure balance device,a radon accumulation chamber,and a support structure.The uniformity and stability of the reference device were evaluated using the activated carbon-γspectrum and open-loop method,respectively,to measure the radon exhalation rate.The reference device achieved different radon exhalation rates by using different activities of diffusion solid radon sources.Nineteen measurement points were regularly selected on the radon exhalation surface of the reference device,and the uniformity of the radon exhalation rate exceeded 5%.The short-term stability of the reference device was better than 5%under different environmental conditions and was almost unaffected by the ambient air pressure,environmental temperature,and relative humidity.
文摘The assay of trace volatile low molecular weight(MW) compounds in human breath or in ambient atmosphere typically involves gas chromatography with flame ionization detection (FID). This paper introduced a direct assay which can overcome the difficulties of collection low concentration samples. In order to pre concentrate the trace low MW compounds, a small trapping column filled with absorbent must be used before thermal desorption of the collected samples onto chromatographic column(packed with Porapak Q) for separation. It has been proved that the characteristic of absorbent mainly influence the recoveries and the linear range of this method is from 0 05 ng to 5200 ng for pentane, methanol, ethanol and acetone.
基金Project nos.K146322&K146315 were implemented with financial support provided by the Hungarian Ministry of Culture and Innovation from the National Research,Development and Innovation Fund financed under the OTKA K_23 funding scheme,Hungary.
文摘Objective:To determine the radium-226 activity concentration,the massic radon exhalation rate and emanation factor of 55 soil samples from the Central Transdanubian Mountains in Hungary as well as possible radon exhalation hotspots in the sampling area were determined.Further indoor measurements are planned to investigate the possible exposure to radon of the inhabitants.Methods:The radium-226 activity concentration measurements were carried out with a semiconductor HPGe gamma-ray spectrometer.The massic radon exhalation rate and emanation factor were determined by measuring the radon activity concentrations using the accumulation method with a system developed by our department based on an AlphaGUARD DF2000 portable radon monitor.Results:The activity concentrations of radium-226 were between(11.42.5)and(118.23.0)Bq/kg,while their average was 39.51 Bq/kg.The massic radon exhalation rates were between(1.023.64)mBq⋅kg1⋅h1 and(275.634.05)mBq⋅kg1⋅h1,while their average was 39.51 mBq⋅kg1⋅h1.Finally,the emanation factors were between(0.010.04)and(0.800.03)with an average of 0.30.Conclusions:In our study,the results recorded from the bedrock at the sampling sites were analyzed.9 samples were taken from sites comprised of limestone bedrock,moreover,the average radium-226 activity concentrations and massic radon exhalation rates at these sampling sites were higher than average.It was also concluded that although no regional correlation can be seen from the results,a possible smaller radon hotspot was identified from our measurements where further sampling will be carried out.
基金financially supported by the National Natural Science Foundation of China(No.11375164 and 12105274).
文摘Objective:To understand the characteristic parameters and radon exhalation rates of aerated concrete blocks.Methods:A total of 39 nationally inspected samples were measured.Their dry density was determined based on their mass and volumes,their porosities were measured on the principle of volumetric expansion,and their radium content was determined using a high-purity germanium(HPGe)detector for gamma-ray spectroscopy.Furthermore,their diffusion lengths were quantified by establishing a combined cumulative and diffusion chamber,and their radon exhalation rates were measured through closed-box testing using a continuous radon monitor.Results:The aerated concrete blocks exhibited dry densities ranging from 464 to 840 kg/m^(3)[average:(654.0±82.5)kg/m^(3)],open porosities from 67.1%to 81.1%[average:(74.3±3.3)%],radium(^(226)Ra)content from 12.3 to 136 Bq/kg[average:(63.0±30.4)Bq/kg],diffusion lengths from 0.49 to 1.01 m[average:(0.70±0.15)m],and radon exhalation rates from 0.6 to 22.8 Bq·m^(-2)·h^(-1)[average:(7.3±5.3)Bq·m^(-2)·h^(-1)].Conclusion:Aerated concrete blocks exhibit significantly higher porosities,diffusion lengths,and radon exhalation rates than traditional concrete and clay bricks.These blocks might contribute to the high indoor radon concentration observed in modern buildings in China.
基金supported by the Thailand Institute of Nuclear Technology(TINT),Thailand.
文摘Objective:To develop a new system to accurately measure the radon exhalation from the latex pillows,and to estimate its potential exposure to users.Methods:The new system is composed of two loops,the first loop is designed to trap background radon and thoron until their levels are nearly zero,and the second loop is the measurement loop to detect radon and thoron exhalation rates from the pillows.Results:The results showed that mass radon exhalation rated ranged from 0.18 Bq·kg^(-1)·h^(-1) to 0.78 Bq·kg^(-1)·h^(-1),with an average of(0.36±0.17)Bq·kg^(-1)·h^(-1) in the 9 samples.The average annual effective dose to users in a model room was estimated to be(15.51±12.69)μSv by assuming two pillows was used.Conclusion:These results demonstrate that the new system can effectively measure radon exhalation rates in latex pillows,and the potential exposure to radon exhalating from the pillows is very low.
基金supported by the Key Research and Development Program of Shaanxi(No.2022ZDLSF01-04)National Natural Science Foundation of China(No.22104117)The First Affiliated Hospital of Xi’an Jiaotong University’s Medical"Basic-Clinical"Integration Innovation(No.YXJLRH2022033)。
文摘Breath analysis can be used to diagnose diseases non-invasively.Accurate measurement of volatolomics is critical for breath analysis to be a gold standard.Tedlar bags(TB)are often used to collect breath samples,but they emit contaminants that affect accuracy.This issue was overlooked in previous studies.We found contamination issues with TB(e.g.,siloxanes and aromatic impurities)that affect the identification of volatile organic compounds(VOCs)due to impurities.Then,home-designed equipment(HD)made with poly-tetrafluoride(PTFE)and quartz glass for breath collection was developed and employed in clinical trials.15 healthy individuals and 32 non-small cell lung cancer(NSCLC)patients at IA stage participated in this study.610 VOCs can be collected through TB,which is less than HD(1109 VOCs),demonstrating that the inner wall of the TB easily adsorbs VOCs,leading to decreased detection concentrations.Otherwise,utilizing orthogonal partial least squares discriminant analysis(OPLS-DA),we identified chemical markers with significant discriminatory power(VIP>1.5,P<0.05).The HD method identified 12 target VOCs,surpassing the 3 target VOCs discerned by the TB method.A model combined with a machine learning algorithm for distinguishing early-stage lung cancer patients was established based on biomarkers,which were selected based on OPLS-DA.The results showed strong predictive capabilities for the HD-based model.It indicated that 12 biomarkers derived from the HD model were more effective in distinguishing NSCLC patients,with an AUC value of 0.92,compared to the AUC value of 0.5 from 3 markers obtained from the TB model.The sensitivity and specificity in the confusion matrix reached 100%and 80%for the HD test,but TB test reached only 40%and 60%.This work demonstrated that optimizing and standardizing VOCs collection methodology from breath of lung cancer patients is essential to identify actual volatiles,which could promote disease volatolomics worldwide.
基金financially supported by the National Natural Science Foundation of China(Nos.62101477,62071410 and 21802114)the Science and Technology Innovation Program of Hunan Province(No.2023RC3133)the Excellent Youth Scholars of Hunan Provincial Department of Education(No.21B0141)。
文摘The exploitation of the highly reliable gassensing device for exhaled acetone detection possesses momentous and capacious development prospects in the field of an early noninvasive diabetes diagnosis.Considering that the characteristics of crystal facets will impact the gas-sensitive performance,herein three different resistive gas sensors were successfully developed by utilizing the stable α-Fe_(2)O_(3)with different crystal facets as the sensitive materials.The gas-sensitive performance testing results reveal that the(110)crystal faceted α-Fe_(2)O_(3)sensor exhibits relatively superior comprehensive gas sensitivity toward acetone.Particularly,it is worth mentioning that the sensor demonstrates reliable sensitivity,rapid response(25 s)/recovery(3 s)speed,and strong anti-interference capability in detecting 2×10^(-6)acetone for the concentration threshold of diabetes,even when exposed to prolonged periods in variable environments.Furthermore,by simply validating the feasibility of the exhalation diagnosis using the as-prepared gas sensor,the(110)faceted α-Fe_(2)O_(3)gas sensor can effectively discriminate the states of healthy human exhalation and the simulated diabetic exhalation.Through integrating the experimental and theoretical analyses,the superior acetone-sensitive performance of the(110)facetedα-Fe_(2)O_(3)gas sensor can principally be interpreted in correlation with crystal facet-dependent gas adsorption capacity and defect-forming ability.These results not only imply a tremendous application perspective in monitoring acetone gas at sub-ppm concentration,but also open up an effective throughway to develop reliable gas-sensing devices for early non-invasive diabetes screening.
文摘The concentration of the heavy isotope of hydrogen, deuterium (D), is not routinely measured in (human) medical laboratory tests, even though an increasing number of papers prove the pivotal role of D in tumor growth, cell cycle regulation, cell metabolism, and aging. Data from a prospective phase 2 clinical study and numerous retrospective clinical studies proved the anticancer effect of deuterium depletion achieved by replacing the regular water intake with deuterium-depleted water (DDW). In previous studies, the changes in serum D concentration of DDW-consuming patients were followed using blood samples and mass spectrometry, which was invasive, costly, and time-consuming. As future clinical trials will also require a follow-up of internal D level and the patient’s compliance, a new sampling device and procedure was developed based on condensing the exhaled breath water vapor and measuring its D content using a liquid water isotope laser analyzer. Test results showed that the device provided accurate, reliable, and reproducible data. According to the data, the internal D level in a person consuming normal water was stable. In contrast, exclusive consumption of DDW for several days resulted in a gradual decrease of D concentration in exhaled breath condensate (EBC), which was proportional to the D concentration of DDW. These data confirm that orally applied DDW equilibrates with the person’s water pool quickly, leading to a reduced internal D level reflected in the D content of EBC.
基金by a grant from the Xinjiang Geological Exploration Fund Project Management Center(Grant No.Y14-5-LQ05)。
文摘The Aqishan lead-zinc deposit,located in the Jueluotag metallogenic belt of eastern Tianshan,Xinjiang,Northwest China,has a stratiform occurrence in the marine volcanic tuff of the Yamansu Formation.The ore body has a typical double-layer structure,having a stratified,stratoid,lenticular upper part and a veined,stockwork-like lower part.The occurrence of the upper orebody is consistent with that of the volcanic tuff wall rock.The ore minerals are mainly chalcopyrite,pyrite,sphalerite,galena and magnetite,the altered minerals mainly being silicified,such as sericite,chlorite,epidote,garnet.The garnetized skarn,being stratiform and stratoid,is closely related to the upper part of the orebody.Geological observations show that the limestone in the ore-bearing Yamansu Formation is not marbleized and skarnized.Spatially,it is associated with the ferromanganese deposits in the marine volcanic rocks of the Yamansu Formation.These geological features reflect the likelihood that the Aqishan lead-zinc deposit is a hydrothermal exhalation sedimentary deposit.The results from the EPMA show that the garnet is mainly composed of grossular-andradite series,contents being in a range of 34.791-37.8%SiO_(2),32.493-34.274%CaO,8.454-27.275%FeO,0.012-15.293%Al_(2)O_(3),0.351-1.413%MnO,and lower values of 0.013-1.057%TiO_(2).The content of SiO_(2) vs.CaO and FeO vs.Al_(2)O_(3) has a significant positive correlation.The results of ICP-MS analysis for the garnet show that the REE pattern is oblique to right in general.The total amount of rare earth elements is relatively low,ΣREE=71.045-826.52 ppm,which is relatively enriched for LREE and depleted for HREE.LREE/HREE=8.66-4157.75,La_(N)/Yb_(N)=23.51-984.34,with obvious positive Eu and Ce anomalies(δEu=2.27-76.15,δCe=0.94-1.85).This result is similar to the REE characteristics of ore-bearing rhyolite volcanic rocks,showing that the garnet was formed in an oxidizing environment and affected by clear hydrothermal activity.The U-Pb isotopic dating of garnet by fs-LA-HR-ICP-MS gives an age of 316.3±4.4 Ma(MSWD=1.4),which is consistent with the formation time of the Yamansu Formation.According to the study of deposit characteristics and geochemical characteristics,this study concludes that the Aqishan lead-zinc deposit is a hydrothermal exhalation sedimentary deposit,the garnet being caused by hydrothermal exhalative sedimentation.
基金supported by Universiti Kebangsaan Malaysia and Lynas Advanced Material Plant under Grant Numbers GGPM-2017-084 and ST-2017-012,respectively
文摘In this study, the activity concentrations of ^(226)Ra,^(232)Th,^(222)Rn, and ^(40)K, emanation fractions(P),equilibrium equivalent concentration(EEC), and mass exhalation rates(E_m) of radon released from building materials used in Malaysia were studied using gamma-ray spectrometer with HPGe detector. Radiological parameters[activity concentration index(ACI), indoor air-absorbed dose rate(D_(in)), annual effective dose(AED_(in)) from external and internal(E_(Rn)), soft tissues(H_(ST)) and lung(H_L), and effective dose equivalent(H_(eff))] were estimated to evaluate radiological hazards due to the use of these building materials: sand, cement, gravel, bricks, tiles, fly ash, white cement, and ceramic raw materials. The measured P, EEC,and E_m vary from 10 to 30%, 0.9 to 22 Bq m^(-3), and 33 to 674 mBq h^(-1) kg^(-1), respectively, while the calculated ACI and AED_(in) vary from 0.1 ± 0.01 to 2.1 ± 0.1 and 0.1 ± 0.01 to 2.4 ± 0.6 mSv y^(-1), respectively. On the other hand, the internal annual effective dose ranges from 0.1 to 1.4 mSv y^(-1). The estimated radiological risk parameters were below the recommended maximum values, and radiological hazards associated with building materials under investigation are therefore negligible.
文摘The aim of our present work is to measure the specific activities of the radionuclides 226Ra, 232Th, 40K and the exhalation rates in terms of area and mass of 222Rn in some samples of building materials commonly used in Morocco in order to evaluate the radiological risk caused by natural radioactivity. To this end, the analyses were carried out, using two nuclear techniques, namely high resolution gamma spectrometry and alpha dosimetry based on the use of LR115, on 50 samples collected from large commercial suppliers in Morocco. The results of these analyses show that the average specific activities of 226Ra, 232Th and 40K in these materials vary from 9 to 52 Bq/kg, 3 to 63 Bq/kg and 68 to 705 Bq/kg respectively. These activities remain within the permissible limits of 35 Bq/kg, 30 Bq/kg and 370 Bq/kg respectively, with the exception of a few samples of red brick, gray cement, ceramic and granite. The activity of the radium equivalent (Raeq), the internal (Hin) and external (Hex) hazard indices, the absorbed dose rate, the total annual effective dose , the excess lifetime cancer risk (ELCR) as well as volumic activities, exhalation rates in terms of area (ES) and mass (EM) are calculated for the samples analyzed in this work in order to assess the radiological risks resulting from the use of these materials in various construction activities. It seems that the values of these indices vary from 19 to 196 Bq/kg, 0.08 to 0.67, 0.05 to 0.53, 9 to 91 nGy/h, 0.05 to 0.56 mSv/y, 0.19 × 10−3 to 1.96 × 10−3, 72 to 350 Bq/m3, 56 to 273 mBq⋅m−2⋅h−1 and 3 to 15 mBq⋅kg−1⋅h−1 respectively. The lowest values are identified for gypsum, while the highest are attributed to granite. All of the obtained results of these indices respect the permissible limits except for the Raeq in some granite samples, the ELCR index in all samples except gypsum and the radon volumic activity in some gray cement samples, ceramic and granite. As a result, the different types of building materials analyzed in our work do not present a health risk to the public and can be used in various construction activities, with the exception of a few samples of red brick, gray cement, ceramic and granite. The choice of the use of red brick, gray cement and ceramic should be monitored and adapted according to the criteria of the limitation of the doses whereas the use of the granite must be moderate in order to limit over time the health risk which increases with the duration of exposure of humans to these building materials.
文摘The radiological impact of coal ashes, with enhanced natural radioactivity in the storage site, is due to the presence of naturally occurring radionuclides. Some of these radionuclides have a radioactive period of several million years and will, therefore, have time to migrate to the soil, atmospheric air, surface water, and groundwater. This impact depends mainly on the activity of these coal ashes, the duration of exposure to such waste, transfers to the air, and the leaching phenomenon by rainwater. In this study, and so as to assess the radiological impact of coal ashes of the storage site of the JLEC-Morocco thermal power plant on environment, some analyses are performed by alpha dosimetry and a digital dosimeter on samples of coal ashes, soil, atmospheric air, surface water and groundwater belonging to a perimeter of 10 km around that site. The obtained results show that, within the studied area, the radiological impact on the soil of the coal ashes of the storage site is insignificant even though the concentrations of radon in the near vicinity (1 to 2 km) are moderately important, and remain below 200 Bq/m3. In the atmospheric air, this impact remains medium for the neighborhoods of the storage site (2 to 3 km) with radon activities superior to 10 Bq/m3. These results also show that there may be a water contamination of wells located at the storage site without any transfer of radioactivity into the groundwater of the area studied where the concentrations of radon are less than 11.1 Bq/l.
基金supported by the China Schorlarship Council (CSC)the Global Center of Excellence (GCOE) in Novel Carbon Resource Sciences, Kyushu Universitysupported by the Zhaokalong Mine, Qinghai, China
文摘The ore types of the Zhaokalong Fe-Cu deposit are divided into two categories： sulfide-type and oxide-type. The sulfide-type ore include siderite ore, galena-sphalerite ore and chalcopyrite ore, whereas the oxide-type ore include magnetite ore and hematite ore. The ore textures and structures indicate that the Zhaokalong deposit is of the sedimentary-exhalative mineralization type. Geochemical analyses show that the two ore types have a high As, Sb, Mn, Co and Ni content. The REE patterns reveal an enrichment of the LREE compared to the HREE. Isotopic analysis of siderite ore reveal that the j13CpDB ranges from -2.01 to 3.34 （%0） whereas the JISOsMow ranges from 6.96 to 18.95 （%0）. The fluid inclusion microthermometry results indicate that homogenization temperatures of fluid inclusions in quartz range from 131 to 181~C, with salinity values of 1.06 to 8.04 wt% NaCI eq. The mineralizing fluid therefore belongs to the low temperature - low salinity system, with a mineralizing solution of a CO2-Ca2＋（Na＋, K＋）-SO42- （F-, CI--H20 system. The geochemical results and fluid inclusion data provide additional evidence that the Zhaokalong deposit is a sedex-type deposit that experienced two stages of mineralization. The sulfide mineralization probably occurred first, during the sedimentary exhalative process, as exhibited by the abundance of marine materials associated with the sulfide ores, indicating a higher temperature and relatively deoxidized oceanic depositional environment. After the main exhalative stage, hydrothermal activity was superimposed to the sulfide mineralization. The later stage oxide mineralization occurred in a low temperature and relatively oxidized environment, in which magmatic fluid circulation was dominant.
基金supported by Fundation of Henan Provincial Medical Science and Technology Research(No.201003098)
文摘Bronchial asthma is a common chronic airway inflammatory disease. Asthma is associated with high mortality, especially in the elderly patients. Repeated exacerbations cause disease progression. Therefore, identifying the onset of acute elderly asthma as soon as possible and giving the effective treatment is crucial to improve the prognosis. This study was to investigate the significance of fractional exhaled nitric oxide （FeNO） combined with serum procalcitonin （PCT） and C-reactive protein （CRP） in the evaluation of elderly asthma. A total of 120 elderly patients with an acute attack of asthma from July, 2010 to May, 2012 were studied. On presentation, FeNO, serum PCT and CRP concentrations were measured and sputum culture was also performed. The elderly patients were re-evaluated when they had returned to their stable clinical state. The elderly patients were classified into two groups： positive bac- terial culture group （A） and negative bacterial culture group （B）. The results showed that： （1） In patients with an acute exacerbation of asthma, 48 （40%） patients had positive sputum bacterial culture and 72 （60%） had negative sputum bacterial culture. （2） The levels of FeNO in patients with acute exacerbation of asthma were significantly higher than in those with no acute exacerbation state （63.8±24.6 vs. 19±6.5 ppb, P〈0.05）. There was no significant difference in FeNO between group A and group B （P〉0.05）. （3） The levels of PCT and CRP in group A patients with an acute exacerbation of asthma were significantly higher （P〈0.05） than in group B （for PCT： 27.46±9.32 vs. 7.85±3.52 ng/mL; for CRP： 51.25±11.46 vs. 17.11±5.87 mg/L, respectively）. When they had returned to stable clinical state, the levels of PCT and CRP in group A were decreased significantly （P〈0.05）, and those in group B had no significant change （P〉0.05） when compared with the exacerbation group. There were no significant differences in the levels of PCT and CRP between the two groups in non-acute exacerbation state （/9〉0.05）. These results suggest that the increase in FeNO indicates the acute exacerbation of asthma, and the elevation of serum PCT and CRP levels may be associated with bacterial infection.
